Real World

Real world cyber crime cases This document is an extract from the book Cyber Crime & Digital Evidence – Indian Perspective authored by Rohas Nagpal. This book is available as courseware for the Diploma in Cyber Law and PG Program in Cyber Law conducted by Asian School of Cyber Laws www. asianlaws. org Cyber Crime & Digital Evidence – Indian Perspective 23. Real World Cases This chapter serves as a ready reference guide. First the various scenarios are covered. A detailed discussion on the various cyber crimes, is covered in the ASCL publication titled â€Å"Understanding Hackers and Cyber Criminals†. This is provided as official courseware for the ASCL Certified Cyber Crime Investigator course. Then the applicable law and legal liabilities are covered. Then the modus operandi usually followed by the criminals is discussed. The investigation guidelines for cyber crime investigators are not discussed in this book as they are part of the syllabus of the ASCL Certified Cyber Crime Investigator course only. For real world case studies on investigation of cyber crimes, please refer to the ASCL publication titled â€Å"Case Studies on Cyber Crime Investigation†. This is provided as official courseware for the ASCL Certified Cyber Crime Investigator course. – 130 –  © 2008 Rohas Nagpal. All rights reserved. Cyber Crime & Digital Evidence – Indian Perspective 23. 1 Orkut Fake Profile cases Orkut. com is a very popular online community and social networking website. Orkut users can search for and interact with people who share the same hobbies and interests. They can create and join a wide variety of online communities. The profiles of Orkut members are publicly viewable. The scenarios 1. A fake profile of a woman is created on Orkut. The profile displays her correct name and contact information (such as address, residential phone number, cell phone number etc). Sometimes it even has her photograph. The problem is that the profile describes her as a prostitute or a woman of â€Å"loose character† who wants to have sexual relations with anyone. Other Orkut members see this profile and start calling her at all hours of the day asking for sexual favours. This leads to a lot of harassment for the victim and also defames her in society. 2. An online hate community is created. This community displays objectionable information against a particular country, religious or ethnic group or even against national leaders and historical figures. 3. A fake profile of a man is created on Orkut. The profile contains defamatory information abut the victim (such as his alleged sexual weakness, alleged immoral character etc) The law Scenario 1: Section 67 of Information Technology Act and section 509 of the Indian Penal Code. Scenario 2: Section 153A and 153B of Indian Penal Code. Scenario 3: Section 500 of Indian Penal Code. Who is liable? Scenario 1: Directors of Orkut as well as all those who create and update the fake profile. Scenario 2: Same as Scenario 1. Scenario 3: Same as Scenario 1.  © 2008 Rohas Nagpal. All rights reserved. – 131 – Cyber Crime & Digital Evidence – Indian Perspective The motive Scenario 1: Jealousy or revenge (e. g. the victim may have rejected the advances made by the suspect). Scenario 2: Desire to cause racial hatred (e. g. Pakistani citizens creating an anti-India online community). Scenario 3: Hatred (e. g. a school student who has failed may victimize his teachers). Modus Operandi 1. The suspect would create a free Gmail account using a fictitious name. 2. The email ID chosen by him would be unrelated to his real identity. 3. The suspect would then login to Orkut. com and create the offensive profile. – 132 –  © 2008 Rohas Nagpal. All rights reserved. Cyber Crime & Digital Evidence – Indian Perspective 23. 2 Email Account Hacking Emails are increasingly being used for social interaction, business communication and online transactions. Most email account holders do not take basic precautions to protect their email account passwords. Cases of theft of email passwords and subsequent misuse of email accounts are becoming very common. The scenarios 1. The victim’s email account password is stolen and the account is then misused for sending out malicious code (virus, worm, Trojan etc) to people in the victim’s address book. The recipients of these viruses believe that the email is coming from a known person and run the attachments. This infects their computers with the malicious code. 2. The victim’s email account password is stolen and the hacker tries to extort money from the victim. The victim is threatened that if he does not pay the money, the information contained in the emails will be misused. 3. The victim’s email account password is stolen and obscene emails are sent to people in the victim’s address book. The law Scenario 1: Sections 43 and 66 of Information Technology Act. Scenario 2: Sections 43 and 66 of Information Technology Act and section 384 of Indian Penal Code. Scenario 3: Sections 43, 66 and 67 of Information Technology Act and section 509 of the Indian Penal Code. Who is liable? Scenario 1: Persons who have stolen the email account password and who are misusing the email account. Scenario 2: Persons who have stolen the email account password and who are threatening to misuse it.  © 2008 Rohas Nagpal. All rights reserved. – 133 – Cyber Crime & Digital Evidence – Indian Perspective Scenario 3: Persons who have stolen the email account password and who are misusing the email account. The motive Scenario 1: Corporate Espionage, perverse pleasure in being able to destroy valuable information belonging to strangers etc. Scenario 2: Illegal financial gain. Scenario 3: Revenge, jealousy, hatred. Modus Operandi 1. The suspect would install keyloggers in public computers (such as cyber cafes, airport lounges etc) or the computers of the victim. 2. Unsuspecting victims would login to their email accounts using these infected computers. 3. The passwords of the victim’s email accounts would be emailed to the suspect. – 134 –  © 2008 Rohas Nagpal. All rights reserved. Cyber Crime & Digital Evidence – Indian Perspective 23. 3 Credit Card Fraud Credit cards are commonly being used for online booking of airline and railway tickets and for other ecommerce transactions. Although most of ecommerce websites have implemented strong security measures (such as SSL, secure web servers etc), instances of credit card frauds are increasing. The scenario The victim’s credit card information is stolen and misused for making online purchases (e. g. airline tickets, software, subscription to pornographic websites etc). The law Sections 43 and 66 of Information Technology Act and section 420 of Indian Penal Code. Who is liable? All persons who have stolen the credit card information as well as those who have misused it. The motive Illegal financial gain. Modus Operandi Scenario 1: The suspect would install keyloggers in public computers (such as cyber cafes, airport lounges etc) or the computers of the victim. Unsuspecting victims would use these infected computers to make online transactions. The credit card information of the victim would be emailed to the suspect. Scenario 2: Petrol pump attendants, workers at retail outlets, hotel waiters etc note down information of the credit cards used for making payment at these establishments. This information is sold to criminal gangs that misuse it for online frauds. 2008 Rohas Nagpal. All rights reserved. – 135 – Cyber Crime & Digital Evidence – Indian Perspective 23. 4 Online Share Trading Fraud With the advent of dematerialization of shares in India, it has become mandatory for investors to have demat accounts. In most cases an online banking account is linked with the share trading account. This has led to a high number of online share trading frauds. The scenario Scenario 1: The victim’s account passwords are stolen and his accounts are misused for making fraudulent bank transfers. Scenario 2: The victim’s account passwords are stolen and his share trading accounts are misused for making unauthorised transactions that result in the victim making losses. The law Scenario 1: Sections 43 and 66 of Information Technology Act and section 420 of Indian Penal Code. Scenario 2: Sections 43 and 66 of Information Technology Act and section 426 of Indian Penal Code. Who is liable? Scenario 1: All persons who have stolen the account information as well as those who have misused it. Scenario 2: All persons who have stolen the account information as well as those who have misused it. The motive Scenario 1: Illegal financial gain Scenario 2: Revenge, jealousy, hatred Modus Operandi Scenario 1: The suspect would install keyloggers in public computers (such as cyber cafes, airport lounges etc) or the computers of the victim. Unsuspecting victims would use these infected computers to login to their online banking and share trading accounts. The passwords and other information of the victim would be emailed to the suspect. Scenario 2: Same as scenario 1. – 136  © 2008 Rohas Nagpal. All rights reserved. Cyber Crime & Digital Evidence – Indian Perspective 3. 5 Tax Evasion and Money Laundering Many unscrupulous businessmen and money launderers (havala operators) are using virtual as well as physical storage media for hiding information and records of their illicit business. The scenario Scenario 1: The suspect uses physical storage media for hiding the information e. g. hard drives, floppies, USB drives, mobile phone memory cards, digital camera memory ca rds, CD ROMs, DVD ROMs, iPods etc. Scenario 2: The suspect uses virtual storage media for hiding the information e. g. mail accounts, online briefcases, FTP sites, Gspace etc. The law Scenario 1: Depending upon the case, provisions of the Income Tax Act and Prevention of Money Laundering Act will apply. Scenario 2: Depending upon the case, provisions of the Income Tax Act and Prevention of Money Laundering Act will apply. Who is liable? Scenario 1: information. The person who hides the Scenario 2: The person who hides the information. If the operators of the virtual storage facility do not cooperate in the investigation, then they also become liable. The motive Scenario 1: Illegal financial gain Scenario 2: Illegal financial gain Modus Operandi Scenario 1: The suspect would purchase small storage devices with large data storage capacities. Scenario 2: The suspect would open free or paid accounts with online storage providers.  © 2008 Rohas Nagpal. All rights reserved. – 137 – Cyber Crime & Digital Evidence – Indian Perspective 23. 6 Source Code Theft Computer source code is the most important asset of software companies. Simply put, source code is the programming instructions that are compiled into the executable files that are sold by software development companies. As is expected, most source code thefts take place in software companies. Some cases are also reported in banks, manufacturing companies and other organisations who get original software developed for their use. The scenario Scenario 1: The suspect (usually an employee of the victim) steals the source code and sells it to a business rival of the victim. Scenario 2: The suspect (usually an employee of the victim) steals the source code and uses it as a base to make and sell his own version of the software. The law Scenario 1: Sections 43, 65 and 66 of the Information Technology Act, section 63 of the Copyright Act. Scenario 2: Sections 43, 65 and 66 of the Information Technology Act, section 63 of the Copyright Act. Who is liable? Scenario 1: The persons who steal the source code as well as the persons who purchase the stolen source code. Scenario 2: The persons who steal the source code. The motive Scenario 1: Illegal financial gain. Scenario 2: Illegal financial gain. Modus Operandi Scenario 1: If the suspect is an employee of the victim, he would usually have direct or indirect access to the source code. He would steal a copy of the source code and hide it using a virtual or physical storage device. – 138 – 2008 Rohas Nagpal. All rights reserved. Cyber Crime & Digital Evidence – Indian Perspective If the suspect is not an employee of the victim, he would hack into the victim’s servers to steal the source code. Or he would use social engineering to get unauthorised access to the code. He would then contact potential buyers to make the sale. Scenario 2: If the suspe ct is an employee of the victim, he would usually have direct or indirect access to the source code. He would steal a copy of the source code and hide it using a virtual or physical storage device. If the suspect is not an employee of the victim, e would hack into the victim’s servers to steal the source code. Or he would use social engineering to get unauthorised access to the code. He would then modify the source code (either himself or in association with other programmers) and launch his own software.  © 2008 Rohas Nagpal. All rights reserved. – 139 – Cyber Crime & Digital Evidence – Indian Perspective 23. 7 Theft of Confidential Information Most business organisations store their sensitive information in computer systems. This information is targeted by rivals, criminals and sometimes disgruntled employees. The scenario Scenario 1: A business rival obtains the information (e. g. tender quotations, business plans etc) using hacking or social engineering. He then uses the information for the benefit of his own business (e. g. quoting lower rates for the tender). Scenario 2: A criminal obtains the information by hacking or social engineering and threatens to make the information public unless the victim pays him some money. Scenario 3: A disgruntled employee steals the information and mass mails it to the victim’s rivals and also posts it to numerous websites and newsgroups. The law Scenario 1: Sections 43 and 66 of the Information Technology Act, section 426 of Indian Penal Code. Scenario 2: Sections 43 and 66 of the Information Technology Act, section 384 of Indian Penal Code. Scenario 3: Sections 43 and 66 of the Information Technology Act, section 426 of Indian Penal Code. Who is liable? Scenario 1: The persons who steal the information as well as the persons who misuse the stolen information. Scenario 2: The persons who steal the information as well as the persons who threaten the victim and extort money. Scenario 3: The disgruntled employee as well as the persons who help him in stealing and distributing the information. The motive Scenario 1: Illegal financial gain. Scenario 2: Illegal financial gain. Scenario3: Revenge. – 140  © 2008 Rohas Nagpal. All rights reserved. Cyber Crime & Digital Evidence – Indian Perspective Modus Operandi Scenario 1: The suspect could hire a skilled hacker to break into the victim systems. The hacker could also use social engineering techniques. Illustration: A very good looking woman went to meet the system administrator (sysadmin) of a large company. She interviewed the sysadmin for a â€Å"magazine article†. During the interview she flirted a lot with the sysadmin and while leaving she â€Å"accidentally† left her pen drive at the sysadmin’s room. The sysadmin accessed the pen drive and saw that it contained many photographs of the lady. He did not realize that the photographs were Trojanized! Once the Trojan was in place, a lot of sensitive information was stolen very easily. Illustration: The sysadmin of a large manufacturing company received a beautifully packed CD ROM containing â€Å"security updates† from the company that developed the operating system that ran his company’s servers. He installed the â€Å"updates† which in reality were Trojanized software. For 3 years after that a lot of confidential information was stolen from the company’s systems! Scenario 2: Same as scenario 1. Scenario 3: The disgruntled employee would usually have direct or indirect access to the information. He can use his personal computer or a cyber cafe to spread the information.  © 2008 Rohas Nagpal. All rights reserved. – 141 – Cyber Crime & Digital Evidence – Indian Perspective 23. 8 Software Piracy Many people do not consider software piracy to be theft. They would never steal a rupee from someone but would not think twice before using pirated software. There is a common perception amongst normal computer users to not consider software as â€Å"property†. This has led to software piracy becoming a flourishing business. The scenario Scenario 1: The software pirate sells the pirated software in physical media (usually CD ROMs) through a close network of dealers. Scenario 2: The software pirate sells the pirated software through electronic downloads through websites, bulletin boards, newsgroups, spam emails etc. The law Scenario 1: Sections 43 and 66 of the Information Technology Act, section 63 of Copyright Act. Scenario 2: Sections 43 and 66 of the Information Technology Act, section 63 of Copyright Act. Who is liable? Scenario 1: The software pirate as well as the persons who buy the pirated software from him. Scenario 2: The software pirate as well as the persons who buy the pirated software from him. The motive Scenario 1: Illegal financial gain. Scenario 2: Illegal financial gain. Modus Operandi Scenario 1: The suspect uses high speed CD duplication equipment to create multiple copies of the pirated software. This software is sold through a network of computer hardware and software vendors. Scenario 2: The suspect registers a domain name using a fictitious name and then hosts his website using a service provider that is based in a country that does not have cyber laws. Such service providers do not divulge client information to law enforcement officials of other countries. – 142  © 2008 Rohas Nagpal. All rights reserved. Cyber Crime & Digital Evidence – Indian Perspective 23. 9 Music Piracy Many people do not consider music piracy to be theft. They would never steal a rupee from someone but would not think twice before buying or using pirated music. There is a common perception amongst people users to not consider music as â€Å"property†. There is a huge business in music piracy. Thousands of unscrupulous businessmen sell pirated music at throw away prices. The scenario Scenario 1: The music pirate sells the pirated music in physical media (usually CD ROMs) through a close network of dealers. Scenario 2: The music pirate sells the pirated music through electronic downloads through websites, bulletin boards, newsgroups, spam emails etc. The law Scenario 1: Sections 43 and 66 of the Information Technology Act, section 63 of Copyright Act. Scenario 2: Sections 43 and 66 of the Information Technology Act, section 63 of Copyright Act. Who is liable? Scenario 1: The music pirate as well as the persons who buy the pirated software from him. Scenario 2: The music pirate as well as the persons who buy the pirated software from him. The motive Scenario 1: Illegal financial gain. Scenario 2: Illegal financial gain. Modus Operandi Scenario 1: The suspect uses high speed CD duplication equipment to create multiple copies of the pirated music. This music is sold through a network of dealers. Scenario 2: The suspect registers a domain name using a fictitious name and then hosts his website using a service provider that is based in a country that does not have cyber laws. Such service providers do not divulge client information to law enforcement officials of other countries.  © 2008 Rohas Nagpal. All rights reserved. – 143 – Cyber Crime & Digital Evidence – Indian Perspective 23. 10 Email Scams Emails are fast emerging as one of the most common methods of communication in the modern world. As can be expected, criminals are also using emails extensively for their illicit activities. The scenario In the first step, the suspect convinces the victim that the victim is going to get a lot of money (by way of winning a lottery or from a corrupt African bureaucrat who wants to transfer his ill gotten gains out of his home country). In order to convince the victim, the suspect sends emails (some having official looking documents as attachments). Once the victim believes this story, the suspect asks for a small fee to cover legal expenses or courier charges. If the victim pays up the money, the suspect stops all contact. The law Section 420 of Indian Penal Code Who is liable? The sender of the email. The motive Illegal financial gain. Modus Operandi The suspect creates email accounts in fictitious names and sends out millions of fraudulent emails using powerful spam software. – 144 –  © 2008 Rohas Nagpal. All rights reserved. Cyber Crime & Digital Evidence – Indian Perspective 23. 11 Phishing With the tremendous increase in the use of online banking, online share trading and ecommerce, there has been a corresponding growth in the ncidents of phishing being used to carry out financial frauds. Phishing involves fraudulently acquiring sensitive information (e. g. passwords, credit card details etc) by masquerading as a trusted entity. The scenario Scenario 1: The victim receives an email that appears to have been sent from his bank. The email urges the victim to click on the link in the email. When the victim does so, he is taken to â€Å"a secure page on the bank’s website†. The victim believes the web page to be authentic and he enters his username, password and other information. In reality, the website is a fake and the victim’s information is stolen and misused. The law Sections 43 and 66 of Information Technology Act and sections 419, 420 and 468 of Indian Penal Code. Who is liable? All persons involved in creating and sending the fraudulent emails and creating and maintaining the fake website. The persons who misuse the stolen or â€Å"phished† information are also liable. The motive Illegal financial gain. Modus Operandi The suspect registers a domain name using fictitious details. The domain name is usually such that can be misused for spoofing e. g. Noodle Bank has its website at www. oodle. com The suspects can target Noodle customers using a domain name like www. noodle-bank-customerlogin. com The suspect then sends spoofed emails to the victims. e. g. the emails may appear to come from [email  protected] com The fake website is designed to look exactly like the original website.  © 2008 Rohas Nagpal. All rights reserved. – 1 45 – Cyber Crime & Digital Evidence – Indian Perspective 23. 12 Cyber Pornography Cyber pornography is believed to be one of the largest businesses on the Internet today. The millions of pornographic websites that flourish on the Internet are testimony to this. While pornography per se is not illegal in many countries, child pornography is strictly illegal in most nations today. Cyber pornography includes pornographic websites, pornographic magazines produced using computers (to publish and print the material) and the Internet (to download and transmit pornographic pictures, photos, writings etc). The scenario The suspect accepts online payments and allows paying customers to view / download pornographic pictures, videos etc from his website. The law Section 67 of Information Technology Act. Who is liable? The persons who create and maintain the pornographic websites are liable. In some cases cyber cafe owners and managers may also be liable in case they knowingly allow their customers to access the pornographic websites. The motive Illegal financial gain. Modus Operandi The suspect registers a domain name using fictitious details and hosts a website on a server located in a country where cyber pornography is not illegal. The suspect accepts online payments and allows paying customers to view / download pornographic pictures, videos etc from his website. – 146 –  © 2008 Rohas Nagpal. All rights reserved. Cyber Crime & Digital Evidence – Indian Perspective 23. 3 Online Sale of Illegal Articles It is becoming increasingly common to find cases where sale of narcotics drugs, weapons, wildlife etc. is being facilitated by the Internet. Information about the availability of the products for sale is being posted on auction websites, bulletin boards etc. The scenario The suspect posts information about the illegal sale that he seeks to make. P otential customers can contact the seller using the email IDs provided. If the buyer and seller trust each other after their email and / or telephonic conversation, the actual transaction can be concluded. In most such cases the buyer and seller will meet face to face at the time of the final transaction. Illustration: In March 2007, the Pune rural police cracked down on an illegal rave party and arrested hundreds of illegal drug users. The social networking site, Orkut. com, is believed to be one of the modes of communication for gathering people for the illegal â€Å"drug† party. The law Depending upon the illegal items being transacted in, provisions of the Narcotic Drugs and Psychotropic Substances Act, Arms Act, Indian Penal Code, Wildlife related laws etc may apply. Who is liable? The persons who buy and sell these items. The motive Illegal financial gain. Modus Operandi The suspect creates an email ID using fictitious details. He then posts messages, about the illegal products, in various chat rooms, bulletin boards, newsgroups etc. Potential customers can contact the seller using the email IDs provided. If the buyer and seller trust each other after their email and / or telephonic conversation, the actual transaction can be concluded. In most such cases the buyer and seller will meet face to face at the time of the final transaction.  © 2008 Rohas Nagpal. All rights reserved. 147 – Cyber Crime & Digital Evidence – Indian Perspective 23. 14 Use of Internet and Computers by Terrorists Many terrorists are using virtual as well as physical storage media for hiding information and records of their illicit business. They also use emails and chat rooms to communicate with their counterparts around the globe. The scenario The suspects carry laptops w herein information relating to their activities is stored in encrypted and password protected form. They also create email accounts using fictitious details. In many cases, one email account is shared by many people. E. g. one terrorist composes an email and saves it in the draft folder. Another terrorist logs into the same account from another city / country and reads the saved email. He then composes his reply and saves it in the draft folder. The emails are not actually sent. This makes email tracking and tracing almost impossible. Terrorists also use physical storage media for hiding the information e. g. hard drives, floppies, USB drives, mobile phone memory cards, digital camera memory cards, CD ROMs, DVD ROMs, iPods etc. They also use virtual storage media for hiding the information e. g. mail accounts, online briefcases, FTP sites, Gspace etc. The law Terrorists are covered by conventional laws such as Indian Penal Code and special legislation relating to terrorism. Who is liable? Terrorists as well as those who help them to protect their information are liable. If email service providers do not assist the law enforcement personnel in the investigation then they are also legally liable. T he motive Keeping terrorism related information confidential. Secure communication amongst terrorist group members. Modus Operandi The terrorists purchase small storage devices with large data storage capacities. They also purchase and use encryption software. The terrorists may also use free or paid accounts with online storage providers. – 148  © 2008 Rohas Nagpal. All rights reserved. Cyber Crime & Digital Evidence – Indian Perspective 23. 15 Virus Attacks Computer viruses are malicious programs that destroy electronic information. As the world is increasingly becoming networked, the threat and damage caused by viruses is growing by leaps and bounds. The scenario Scenario 1: The virus is a general â€Å"in the wild† virus. This means that it is spreading all over the world and is not targeted at any specific organisation. Scenario 2: The virus targets a particular organisation. This type of a virus is not known to anti-virus companies as it is a new virus created specifically to target a particular organisation. The law Scenario 1: Sections 43 and 66 of Information Technology Act and section 426 of Indian Penal Code. Scenario 2: Sections 43 and 66 of Information Technology Act and section 426 of Indian Penal Code. Who is liable? Scenario 1: The creator of the virus. Scenario 2: The creator of the virus as well as the buyer who purchases the virus (usually to target his business rivals). The motive Scenario 1: Thrill and a perverse pleasure in destroying data belonging to strangers. Scenario 2: Illegal business rivalry. financial gain, revenge, Modus Operandi Scenario 1: A highly skilled programmer creates a new type or strain of virus and releases it on the Internet so that it can spread all over the world. Being a new virus, it goes undetected by many anti-virus software and hence is able to spread all over the world and cause a lot of damage. Anti-virus companies are usually able to find a solution within 8 to 48 hours.  © 2008 Rohas Nagpal. All rights reserved. 149 – Cyber Crime & Digital Evidence – Indian Perspective Scenario 2: A highly skilled programmer creates a new type or strain of virus. He does not release it on the Internet. Instead he sells it for a huge amount of money. The buyer uses the virus to target his rival company. Being a new virus, it may be undetected by the victim company’s anti-virus software and hence would be able to cause a lot of damage. Anti-virus companies may never get to know about the existence of the virus. – 150 –  © 2008 Rohas Nagpal. All rights reserved. Cyber Crime & Digital Evidence – Indian Perspective 3. 16 Web Defacement Website defacement is usually the substitution of the original home page of a website with another page (usually pornographic or defamatory in nature) by a hacker. Religious and government sites are regularly targeted by hackers in order to display political or religious beliefs. Disturbing images and offensive phrases might be displayed in the process, as well as a signature of sorts, to show who was responsible for the defacement. Websites are not only defaced for political reasons, many defacers do it just for the thrill. The scenario The homepage of a website is replaced with a pornographic or defamatory page. In case of Government websites, this is most commonly done on symbolic days (e. g. the Independence day of the country). The law Sections 43 and 66 of Information Technology Act [In some cases section 67 and 70 may also apply]. Who is liable? The person who defaces the website. The motive Thrill or a perverse pleasure in inciting communal disharmony. Modus Operandi The defacer may exploit the vulnerabilities of the operating system or applications used to host the website. This will allow him to hack into the web server and change the home page and other pages. Alternatively he may launch a brute force or dictionary attack to obtain the administrator passwords for the website. He can then connect to the web server and change the webpages.  © 2008 Rohas Nagpal. All rights reserved. – 151 – www. asianlaws. org Head Office 6th Floor, Pride Senate, Behind Indiabulls Mega Store, Senapati Bapat Road, Pune – 411016. India Contact Numbers +91-20-25667148 +91-20-40033365 +91-20-64000000 +91-20-64006464 Email: [email  protected] org URL: www. asianlaws. org

Conclusion and recommendation Essay

Based on the results of the focus group discussion and the interview, Web 2. 0 applications being utilized for educational purposes are seen to have a very good potential in being integrated into educational processes for teaching and learning. Reflective of the first objective, it has been seen that there is a positive outlook with regards to Web 2. 0 applications from students and how the communicate. In addition, it is seen that educational processes would from time to time inculcate particular. Web 2. 0 applications and replacing conventional educational tools with newer and more technologically adept Web 2.0 applications in order for educators to be more effective in communicating with students. With respect to the sixth objective of this study, educators are keen to note that Web 2. 0 applications have the potential for being used as a tool for educational purposes. Educators on one hand furthered this conclusion because of their openness to the concept of including Web 2. 0 applications in their curriculum, utilizing its capabilities in effectively transferring knowledge to their students and more importantly communicating with them. In answering objectives two and three, educators themselves indicated that they are able to already utilize Web 2. 0 applications for providing administrative information to their students and they have indicated that Web 2. 0 applications being used as educational tools already exists and is being utilized by other educators. They are able to go with the flow of innovation as students are getting more and more adept with the use of such internet tools that they are able to identify with this and use this to the teacher’s advantage. The educators have identified that Web 2. 0 applications such as Blogs, Wikis, and other social networking tools have the potential to be used as teaching tools. Being able to use such a tool would not only make their teaching efforts easier but more importantly more effective in bringing information to their students. Coming from the aim of the study particularly to identify how Web 2. 0 technologies can be applied to Higher education, it is apparent that due to the inputs coming from both the student body and educators and because of extant literature there is an apparent improvement in the use of Information Technology in higher education. With the current use of Web 2. 0 technologies such as that of Flickr, Wikis and Myspace by both students and educators in communicating and teaching learning, Web 2. 0 technologies in the future will most certainly be integrated into higher education. This is due to the cultural changes that are observed within educators and students as how they perceive Web 2. 0 technologies and their effect on higher education. This is already evident as students currently utilize such Web 2. 0 applications in communicating with their peers for educational purposes. The next phase would be to utilize such tools more effectively and efficiently by the educators themselves in communicating with their students. On the other hand, because of such an increase in utilization, it would be constructive for this area of educational research if there are additional in-depth studies pertaining to Web 2. 0 technologies and how they affect higher education. In order to further explain and expound on this body of knowledge, it is recommended that a considerable number of focus groups be added into the study. This would yield a more accurate and diverse collation of answers. This would then be used in acquiring more information and validating the results of this study. In addition to the methodology, there should be an inclusion of several interviews to be conducted on other areas particularly other educational classes and universities so as to identify the relationship of geography with Web learning. In addition to this, it would be useful to identify if there is a relationship between racial background and web learning, is there a trait that controls the preferences of various races utilize web 2. 0 applications and if there is a relationship with race. Lastly, In addition to what was mentioned above, it would prove crucial if there is further study with regards to other countries and how they are able to utilize Web 2. 0 applications in their pursuit for better education. This would be able to provide the research with a better comparison particular to the effects of countries with respect to Web 2. 0 applications and Web learning.

Education and Society Essay

Education in the United States has become a crucial part of every American’s life. Completing high school opens doors for individual achievement and is directly linked to economic success. But equally important to the completion of high school is a rich and positive experience in the learning process. Educators are skilled in creating great learning experiences and to enhancing the curriculum, while parents are even more influential. Parents are the positive influence for many children who would otherwise be drastically falling behind, failing, or even dropping out of school. The child’s family background, combined with passed down values and experiences will determine the student’s high school education. The role of technology in early childhood education is an effective tool for students, so the lack of technology in a child’s upbringing can affect their educational career. For example, students who do not begin using various types of technology from kindergarten can fall behind. Studies found that students who are less likely to access technology at home can be at an academic disadvantage. This shows how vital technology is in a child’s education, however there is a challenge in making it available to everyone. Particularly low-income or minority college students could have trouble in succeeding in a technology-saturated environment. Some parents don’t parents don’t understand the importance of Internet access, since in their generation, the Internet was a luxury, not a necessity. However, the bigger issue seems to be the gap between Whites who have access to the Internet and minorities. Studies found that â€Å"56% of Latino adults and 60% of African American can use the Internet,compared to 71% of White adults. The same organization finds that while 42% of white families and 41% of Latino 2 families 666subscribe to broadband access,only 31% of African American households have such access. † Even if lower income schools computer labs students need to build their skills at home as well. Early childhood reading for children can bring a positive outcome to a child’s life. What a child learns in their early years are things that will continue to helps them along in their future in school and in the real world. When a child is introduced to early childhood education, they can get many benefits from it. Benefits include learning to interact in new situations, use critical thinking and basic speech skills before kindergarten. According to Maryanne Wolf, â€Å"In most underprivileged communities, no children’s books were found in homes; in the low come to middle income community there were, on average three books; and in the affluent community there were around 200. † Parents need to create an atmosphere where reading takes place in order to show the importance of reading, but low-income families are falling behind. Parents from affluent communities are able to gain access to understanding the importance of reading while parents from lower income don’t have the resources. Its unclear why low income families don’t have as many books in the home, but the issue might be attributed to a poor school library, lack of understanding for the importance of books, or the obvious issue with low financial resources to buy books. Parents from different language background and parents who aren’t literate in English, will likely raise children who have to play catch-up once they enter kindergarten. Reading can’t just happen over night– it needs to be developed over time. If books are limited, discussions and thoughts aren’t spoken out loud, and this can result in problems. Catherine snow of Harvard and her colleagues found that in addition to literacy materials,one of the major contributors to later reading was simply the amount of time for â€Å"talk around dinner† The 3 importance of simply being talked to, read to, and listened to is what much of early development is about†. In a low-income, busy and hard-working parents may not have time to have these simple talks, or even the financial resources to purchase books for there children. These are two important ingredients for a strong educational upbringing that many low-income family parents can not afford. Even though socioeconomic status and the access to technology are key a family’s behavioral and cultural backgrounds have an equal influence on a student. A child is instinctively drawn toward the background of their parents and social settings to learn what is deemed from right to wrong. According to David Brooks â€Å"Educated parents not only pass down resources to their children, they pass down expectations, habits, knowledge and cognitive abilities. Pretty soon you end up with a hereditary meritocratic class that reinforces itself generation after generation†. What David Brooks is saying is that even though the United States has universal access to higher education such as community college but some students may not be â€Å"physiologically prepared and culturally prepared for college†. Children are reaching their parents expectations and are just continuing a cycle. If parents aren’t showing their support in a educational and motivational sense, kids won’t feel the need to fulfill higher education. The time to instill values of education is not when a child becomes a senior in high school; rather the time to start discussing educational values to a child, is the onset of school, preschool. Education provides an individual their path to a successful future, but only through hard work, dedication and determination is this achievable. Education requires a parent to mold a child into an individual that is capable of contributing effectively to society. The drive to learn must be aroused in children and started at an early age.

Personality- VALS SURVEY Essay Example | Topics and Well Written Essays - 250 words

Personality- VALS SURVEY - Essay Example Even if a fail in certain attempts, I do not give up and think that I cannot achieve a particular goal and instead I continuously try different methods to attain that goal (Lynch, 2007). The survey even depicted that that I even belong to the category of experiencers. This is quite true about me because I am quite enthusiastic about different things and I am always ready to experience new things (Hawknis, 2011). For example: if a project is being assigned to me during the class, I will become quite enthusiastic and I will start asking questions to the instructor and indulge in developing a group for the project. I will even start exploring possible different ways to work on the project and obtain input from other team members regarding the project. Team members come up with different ideas that I am not aware of, but I am always ready to test those ideas and identify the costs and benefits associated with those ideas. But the problem is that I tend to get tired or bored with new things quite easily and I have witnessed that in my consumption patterns (Applegate, 2007). For example: while buying a new LED TV I was very enthusiastic about it and I believed that I will use it to view too many movies. But after only two months, I became bored of it and I quite rarely view movies on

Leadership Essay Example | Topics and Well Written Essays - 250 words - 53

Leadership - Essay Example I would also share my concerns with her supervisors. This is a good strategy as she will be now monitored closely to avoid instances of corruption in her duties. Also, it will enable the organization to retain a good brand name as any miscellaneous operations will be limited. It is apparent that by informing her supervisors they will create a forum to have a refresher course on good corporate governance. This will help the disingenuous leader to know what is expected of her in her duties (Dubrin, 2012). In conclusion, the consequences of telling the truth to her supervisors may lead to firing of the disingenuous leader. This will happen if evidence is found of her improper dealings that are not aligned to the code of ethics of the organization. Also, the organization staff will have unity in achieving the organization set goals as there will be less conflict of interest in the day to day operations. It will be possible as the top management will keen in identifying the weaknesses of various leaders in the

Harriet Beecher Stowe Essay Example | Topics and Well Written Essays - 1250 words

Harriet Beecher Stowe - Essay Example Harriet Beecher Stowe was one of the most famous female abolitionists and authors of the 19th century. Her writings fueled the anti-slavery movements before the Civil War. She used religion and family to connect with her white readers and relate the African American community to them. Stowe later housed fugitives on the Underground Railroad while living with her husband in Brunswick, Maine. She wrote and expressed her opinions at a time when women were repressed. She had no rights to vote or hold office but she made her opinions known and began the public debate on slavery and abolition. Her upbringing contributed to her anti-slavery feelings. Her father was a preacher and he encouraged his children to take action to better society. She was the middle child and had 11 siblings. Six of her brothers became ministers and her older sister pioneered education for women in the early nineteenth century. Stowe had a very self-righteous upbringing from her parents and this encouraged her to take a stand for social justice.

Affluenza in Austrail Essay Example | Topics and Well Written Essays - 750 words

Affluenza in Austrail - Essay Example The article by Hamilton which is entitled the Affluenza in Australia is the main focus of the study. There are different concepts related to affluenza presented in the article which revolves on the relationship of wealth and the fulfillment of the people in life. Based on the report, people in Australia are becoming decreasingly dissatisfied with their life regardless of the increasing trend of income in the country (Hamilton 2005, 16). The article presented different situations in the way of life in Australia that can be considered as indications of affluenza. One is the view that ‘people that are wealthy on the basis of international or historical standard’ have the notion that their way of life is tough. Even 62 percent of the population in Australia has the perception that they have no capability to buy the things they need (Hamilton 2005, 16). This is considered as affluenza since on the basis of the material things owned by the households in Australia, the lifestyle of the people there can be considered as luxurious. This can be observed on the basis of different examples such as the size of houses, the household appliances and the average income of the people (Hamilton 2005, 16). There are different points to analyze the article. These include the components of the article, the points presented and the empirical data and evidences presented which present the relationship to affluenza in the Australian society. In terms of the components and manner of presentation of the data, the article can be considered to lack certain parts such as the presentation of the main objectives and methodology used in the study. These components are considered important in an article to be able to point out the reliability of the information. Such components are required for both quantitative and qualitative studies. In terms of the article title, it can be considered to represent a broad area that includes all the issues related to affluenza

Evaluation of your learning Essay Example | Topics and Well Written Essays - 1000 words

Evaluation of your learning - Essay Example The drive to establish student self-worth is a part of the hidden curriculum within the Lifelong Learning Curriculum. The hidden curriculum is characterized by its intention to unconsciously include learning experiences into the overt curriculum. The hidden curriculum aspires to help students acquire social values and skills (Cornbleth 1990, 50). Another significant feature of the Lifelong Learning curriculum is that the students acquire a â€Å"relevant range and high quality groundwork of knowledge and skills† that are conducive to preparation for the workforce, the maintenance of good interpersonal relations and for sustaining a life replete with creativity and imagination (Chapman and Aspin 1997, 76). Ultimately, the Lifelong Learning curriculum seeks to ensure that education and training are arranged so as to meet the wider societal need of producing workers who can become engaged in the world’s labour market in a competitive manner (Chapman and Aspin 1997, 76). The Lifelong Learning curriculum makes provision for student learning assessment. By taking this approach students take on responsibilities for managing their learning. They are encouraged to state their objectives and to periodically assess and have their progress toward those goals assessed. Ultimately, this approach not only improve the student’s learning, but also contributes to it (Wankel and DeFillippi 2008, 157). Cumulatively, the Lifelong Learning Curriculum is designed to ensure that teaching focuses on student learning. The focus is on learning so that students gain attitudes and skills necessary to learn for themselves in both during education and after completing their education. The Lifelong Learning curriculum takes an approach that reflects a recognition that learning takes place in a number of different contexts in both academic and non-academic constructs as well as in the community, employment and at home. In this regard, the Lifelong

Managing High Performance Essay Example | Topics and Well Written Essays - 250 words - 2

Managing High Performance - Essay Example There is collective ownership of the work. On the other hand, autocratic system excessive control in the autocratic system creates resentment, absenteeism and increased turnover. Decentralized system is favorable to centralized system. Though certain decisions will have to remain at the main office, certain functions will be left with the smaller units. In the decentralized system, each of the units will have the power to make their own decisions as regards most matters. This will help in greater participation by the employees in the project work, and will foster faster decision making (Reddin, 1999). Self directed work teams are preferable to conventional teams (Wright, 2006). The self directed work teams are particularly important because it is the team- not the supervisor which assigns the work, the team completes the whole piece of work, are responsible for and have the authority to correct problems with work flow as they occur. In addition, the team also receives rewards and feedbacks at the team level. This reinforces hard

HIV Patients Should Have Equal Access to Kidney Transplantation Essay Example for Free

HIV Patients Should Have Equal Access to Kidney Transplantation Essay HIV infection may be obtained by patients receiving renal replacement therapy (RRT) through blood transfusions, renal allograft, sexual contacts, or needle sharing of drug addicts. Viral infection or HIV-associated nephropathy can cause renal failure. In the early 1980’s, prognosis of patients with the acquired immunodeficiency syndrome (AIDS) was very low, and survival rate of HIV-infected individuals with ESRD was miserable. Accordingly, several people even doubted the worth of providing continuance dialysis to patients with AIDS. Due to progress in diagnostic techniques in serologic and viral markers of disease, and use of extremely efficient antiretroviral agents, the prognosis of HIV-positive individuals has radically improved. Today, skills and knowledge in hemodialysis are effective modes of therapy and many centers, though some are reluctant, are now starting to practice renal transplantation in HIV-infected patients. Human Immunodeficiency Virus HIV infects CD4+ T cells, making the immune system weak as these cells malfunctions. Abnormal activation ofCD8= T cells may contribute to the loss of both CD4+ AND CD8+ T cells through apoptosis, which may represent a major cause of infected and non-infected cell death in HIV infection. Many HIV-infected individuals proliferative responses to recall antigens, irradiated stimulator peripheral blood mononuclear cells from healthy, unrelated donors, or T cell mitogens (Roland Stock, 2003). HIV infection can worsen existing renal disease and can trigger pathologically distinct disease named HIV-associated nephropathy (HIVAN), a focal segmental glomerulosclerosis (FSGS) associated with severe cystic tubular lesions, leading to chronic renal failure. Renal syndromes include: fluid and electrolyte malfunction, proteinuria, nephrotic disease, progressive azotemia, inflamed kidneys, and fast succession to end stage renal disease (ESRD). HIV-infected patients who developed renal disease have short survival span. Transplantation process may increase the risk of HIV-infected patients in accelerating the depletion and dysfunction of their CD4+ T cells, which may further result in the development of more serious and complicated disease, such as AIDS, making HIV replication harder to control. On the other hand, immunosuppression might reverse the immuno-pathology associated with HIV disease (Roland Stock, 2003). End Stage Renal Disease  When the kidney totally lost its ability to filter waste from the circulatory system, renal failure finally meet the end stage renal disease or ESRD, the final stage of nephropathy or the premeditated degeneration of the kidneys. In 1998, over eighty-six thousand patients received therapy for treating ESRD in the United States. Autonomously, Medicare expenditures rose to 12. 9 billion dollars from 12 billion in 1998. The total cost of ESRD program through medicare was 17. 9 billion and is now projected to be 28. 3 billion dollars by 2010 (Winsett et al, 2002). The most common causes of ESRD include diabetic nephropathy, systemic arteral hypertension, glomerulonephrities, and polycystic kidney disease. In the case of ESRD, GFR declines to less than 10mL/min/m2, once it declines to that level, the normal hemeostatic function of the kidneys can not be sustained anymore. Whatever the cause, if untreated, ESRD may cause severe infection and even death to the patient. When the kidney function decline to less than twelve percent to fifteen percent, the patient survival will depend on the kidney transplantation and the therapies associated to it (Winsett et al, 2002). Chronic Dialysis versus Kidney Transplantation According to the New England Journal of Medicine (1999), transplantation is superior in saving life than long-term dialysis. The mortality rates were analyzed among over 200, 000 patients who underwent dialyses for ESRD and only twenty-three thousand received a kidney. Based on the research, patients who undergo transplantation live twice more than the projected years of life of patients who remained on the waitlist having dialysis. A successful transplantation improves the quality of life and lessens the mortality rate for many patients. Moreover, it consumes less time and energy. However, this procedure may cause bleeding, damage, and infection to other organs inside the body, even death can occur. That is why after transplantation, patients must undergo immunosuppression process for a lifetime period to monitor signs of rejection (Berns, 2007). Despite the greater risks, when it comes to quality and length of life, a transplanted kidney is more preferred. It’s man over machine. Statistics Over ten thousand kidney transplantations are being performed each year on patients with ESRD. Records show that patients who undergo kidney transplantation live longer than those who are just taking dialysis; but eight to nine patients on the waitlist die every day due to scarcity of organs to be used in the transplantation. Cadaveric kidney supply has an average of more than two years to come, and only 15-20 % of patients in the list were granted to receive them. The condition of renal failure and what causes them have direct effects on the transplantation rates of patients. Individuals with cystic kidney disease (25. 5%), obstructive nephropathy (24. 9%), and glomerulonephrities (23. 2%) have the utmost successful transplantation rate while patients having diabetes (13. 3%) and hypertension (8. 5%) have the lowest rates (Wallace, 1998). Why transplantation should be considered in HIV-infected patients? Organ malfunction has been the principal grounds of morbidity and mortality of HIV-infected patients, AIDS-related complication is only secondary. Before, immunosuppression was thought to be an unconditional contraindication in the circumstance of HIV infection, now, it is gradually more valued that immune activation is a major aspect of HIV pathogenesis. Consequently, immunosuppression has advantageous effects in people with HIV infection through temperance of immune activation or reduction of HIV reservoirs. Some specific immunosuppressant agents also have antiviral properties or interact synergistically with certain antiretroviral agents (Roland Stock, 2003). Reasons for reluctance of performing Kidney Transplantation for HIV-infected patients: In a survey conducted to 248 renal transplant centers in The U. S. in 1998, 148 requires HIV testing of prospective kidney recipients and that the vast majority denies patients with HIV to undergo transplantation. Most centers believe that transplantation is not suitable for HIV-infected patients (Spital A. , 1998). Before, chronic dialysis was the only option for treating ESRD of HIV-infected patients for fear of increased morbidity and mortality due to therapeutic immunosuppression. The allocation of cadaver kidneys to these patients was also considered improper due to expected inferior patient graft survival (Anil Kumar et al. , 2005). Also, according to the research led by Professor Andrew Grulich from the University of the New South Wales’ National Centre in HIV Epidemiology and Clinical Search (NCHECR), immune deficiency is responsible for the increased risk of contracting several types of cancer than the general population. HIV patients are eleven times more expected to develop Hodgkin’s lymphoma while there is almost four times the risk for those who had transplants (Staff Writers, 2007). Professor Grulich further proposed that people’s immune system must be maintained at a higher level through the use of anti-retroviral drugs. The main historical exclusion of HIV-infected patients with ESRD was rooted in the coherent basis that immunosuppression necessary for organ transplantation would aggravate an already immunocompromised state. Although there were numerous initial reports signifying worse outcomes after solid organ transplantation in HIV seropositive recipients, there have been reports as well suggesting there were no unpleasant effects of HIV infection on allograft survival (University of California, 2007). Indeed, there have been two reports of HIV-infected patients going through liver or renal transplantation who demonstrated normal graft function for at least eight years following the transplant. The HIV status of the two was unknown at the time of transplantation; therefore no endeavors were prepared to adjust immunosuppressive therapy. The distinction in these studies may recount to differences in the time of HIV acquisition, with those of longstanding HIV infection prior to transplantation having a faster end relative to those who acquired HIV infection at the time of transplantation. Regardless of standard cyclosporine-based immunosuppressive treatments, there was no proof of OI or progression to AIDS in the first eight years following transplantation (Roland Stock, 2003). There are multiple other reports of patients with HIV who had gone through transplantation and demonstrated long-term graft survival in the presence of immunosuppression with variable rates of developing AIDS or death. Six of eleven renal allografts were functioning at a mean follow-up of thirty-one months (Roland Stock, 2003). Effects of Immunosuppressant Agents In order to avoid rejection reaction of the body against transplanted organs, immunosuppressant drugs are being taken to block the immune system from attacking the transplanted organ and preserving its function. As side effect, these drugs can help in HIV progress to AIDS. However, recent studies show that these drugs can also contribute in the reduction of HIV. Inactive T lymphocytes serve as a vital reservoir for HIV regardless of HAART. Immunosuppression may affect the reservoir of HIV-infected cell that persist throughout HAART through reduction of cell-associated HIV by either direct inhibition of viral replication, potentiation of HAART effects, or exhaustion of infected cells and lessening in the accessibility of permissive target cells by preventing T-cell activation. Otherwise, improvement in viral reservoirs can be caused by reduced immune management of HIV-expressing cells (Roland Stock, 2003). Ethical and Medical Issues Organ shortage is one of the ethical issues in organ transplantation. One distributive fairness criteria is equal access which include length of time waiting (first come, first saved basis), and age (youngest to oldest). The supporters of this criteria has a strong belief that since kidney transplantation can save live, it is an important remedial practice and worth offering to anyone who needs it (Center for Bioethics, 2004). The second type is the maximum benefit, aiming to maximize the quantity of successful transplants. The maximum benefit criteria include medical need (the sickest people are being prioritized for a transplantable organ), and probable success of a transplant (giving organs to the person who will be most likely to live the longest). People who support the maximum benefit philosophy aspire to avoid the wasting of organs, which are quite scarce, so that the greatest benefit is derived from every available organ (Center for Bioethics, 2004). During the Pre-HAART era, HIV-infected patients have a very poor prognosis, many people believes that it would be a waste to use the limited supply of organ to those group of patients that is why many transplant centers are reluctant to practice the transplantation. However, now that the HAART has been launched and the mortality and morbidity rate has been decreasing, it would be unethical to withhold this option in the absence of evidence that it is either unsafe or ineffective. Advancement in HIV Therapy: HAART era Highly Active Antiretroviral Therapy (HAART) has been the primary improvement in the treatment of HIV-infected patients in the previous decade. Numerous studies and observations had proven that advantageous outcomes of HAART also include improvement of HIV-related renal complications. Virologic and histologic evidences imply that HIVAN perhaps the result of HIV-1 reproduction in the kidney. The potential relation of HIVAN with HIV-1 replication in the kidney is associated with epidemiologic and medical records showing that HAART may improve HIVAN. On the other hand, from nephrologist’s perspective, one effect of this achievement has been the emergence of new kidney diseases related to (1) enhanced management of the HIV infection and (2) the prospective nephroxicity of antiretroviral treatments. According to the studies of MD Roland and Stock, medical tests have confirmed apparent survival benefits linked with the use of protease inhibitor (PI)-containing or non-nucleoside reverse-transcriptate inhibitor (NNRTI)-containing regimens (HAART). Epidemiologic statistics show reduced mortality, hospitalization rates, and opportunistic infection (OI) incidence associated with HAART. There have been vivid decline in new AIDS-related OIs, the majority of which are now occurring in people with low CD4+ T cell counts and those who are not receiving medical care (University of California, 2007). Epidemiologic and modeling information sustain the clinical trial efficacy data, signifying that HAART has a considerable effect on medical result (Roland Stock, 2003). Survival Rate Using the United States Kidney Data System (USRDS) data, the Journal of the American Society of Nephrology analyzed and studied these inputs to find out whether recipient HIV serologic status remains the primary factor in graft and patient survival in modern clinical transplantation. Ninety-five percent of the HIV-infected patients survived after transplantation and only 4. 3% died. Although in the earlier USRDS studies of kidney recipients before the introduction of HAART, the results showed that HIV-infected recipients had a survival of eighty-three percent while the uninfected patients have eighty-eight percent survival rates. While endurance records of HIV-infected and HIV-uninfected patients is almost the same, selection bias may have occurred, prioritizing the healthier patients than HIV-infected individuals. Also, in the studies of MD Roland, data showed that graft survival and rejection rates of HIV-infected patients who had gone through transplantation were similar to those HIV-negative patients (Roland Stock, 2003). Studies and Observations Methods. This study aims to observe safety and success of kidney transplantation, and learn the effects of immunosuppressant treatments on HIV infection, with the approval of the Institutional evaluation board of two universities: the Drexel University College of Medicine and Hahnemann University Hospital. Forty-five recipients with HIV infection from February 2001 to January 2004 were observed. Patient inclusion criteria were maintenance of HAART, plasma HIV-1 RNA of 400 copies per milliliter, absolute CD4 counts of at least 200 cells per micro liter. Immunosuppressant treatment includes the use of basiliximab stimulation and maintenance with cyclosporine, sirolimus, and steroids while HAART was still being applied after the transplant. Biopsy detected acute rejection; methylprednisolone was used as a treatment. Every after twelve months, surveillance biopsies are being done and evaluations include testing for subclinical acute rejection, chronic allograft nephropathy, and HIVAN (Anil Kumar et al. 2005). Results. The results demonstrated that patients with HIV infection who maintained HAART are capable of increasing an immune reaction, as proven by twenty-five percent rejection rate, signifying allograft reactivity is preserved and that no immunosuppression will lead to allograft rejection. The data showed that the combination of HAART and low-dose immunosuppressant drugs is not associated with serious adverse effects (Anil Kumar et al, 2005). The records show one- and two-year patient survival rate of eighty-five percent and eighty-two percent respectively, in comparison to the reported fifty-eight percent and forty-one percent survival of patients on dialysis. The United States Renal Data System accounted a one-year death rate of 32. 7% in HIV patients uphold on dialysis. The graft survival in this series of HIV-infected recipients is comparable to the UNOS data on non-HIV recipients (Anil Kumar et al, 2005). The monitoring of combined immunosuppression and HAART due to major drug interactions needs thorough supervision and synchronized care of transplant professionals, pharmacists, and HIV specialists. The overall result of this study proves that kidney transplantation in selected HIV-positive patients who were maintained on effective HAART is safe and has higher one to two year patient survival compared to dialysis treatment of selected HIV patients. Actual graft survival in HIV recipients is equivalent to other high-risk groups. The patients observed didn’t developed AIDS or opportunistic infection caused by immunosuppressant agents. Therefore, positive HIV status should not be considered a contraindication for kidney transplantation in selected patients. Conclusion Ethical concerns and safety of transplantation and post-transplant immunosuppressant treatment in HIV-positive recipients advances radically in recent years. Due to improvements in morbidity and mortality, the safety of this complicated intervention was further evaluated. The preliminary outcomes are promising. Proper management and control of transplantation team will determine the success of the renal transplantation. Since many advancements and developments regarding the HIV therapy, kidney transplantation is now possible for HIV-infected patients as morbidity and mortality rate keeps on decreasing. Therefore, with all the results of the research studies and observations, there is sufficient evidence that can support the equal access of patients with HIV infection on kidney transplantation.

Necessity of Parental Spiritual Leadership

Necessity of Parental Spiritual Leadership In this paper, I will show why I believe the parents are to be the primary spiritual caregivers of their children. I believe that there is more than just personal preference deciding who should train children spiritually. This has been a topic of much discussion and one that needs to be brought to the attention of parents. Parents in North America have largely left the spiritual raising of their children up to the church. This is why there are many children and family pastors. I believe that the churchs role is to support the parents in raising children spiritually. It would help to begin by defining some terms. When talking about spiritual leadership, what then is meant? Spiritual leadership is quite simply leadership that is spiritual. Leadership is the act of leading a group of people. This can be by taking somebody from one place and moving them to another by being an example and correcting should the need arise. Spiritual leadership takes the idea of leadership one step further by making it about leading somebody spiritually. What then isÂÂ   meant by spiritual in spiritual leadership?ÂÂ   Spiritual pertains to the realm of religion. In this paper, spiritual will refer to the leading and following of Jesus Christ. Now that spiritual leadership has been defined who can be spiritual leaders? Spiritual leaders can be anybody who is farther along on the faith journey than the one theyre leading. This might include pastors, teachers, leaders, parents, older siblings, or older individuals in the church. In some cases, the spiritual lead er is younger than whom he is leading. Why do children need spiritual leadership? George Barna in his book on transforming children[K1], says that in order to have a proper relationship with God, children must be taught to obey Him.[1] Children need someone to guide them along this journey of life to becoming more like Christ. They need someone to teach them the things of God. They will not and cannot do that on their own. They are in dire need of someone to guide them who is more spiritually mature than they are. What does spiritual leadership have to do with families? Moses wrote in Deuteronomy chapter 6 These words, which I am commanding you today, shall be on your heart. You shall teach them diligently to your sons and shall talk of them when you sit in your house and when you walk by the way and when you lie down and when you rise up.[2] These verses give a clear indication that children are to be taught the things of God by their parents. These words were spoken by Moses as a direct command from God. God was to be taught about by the parents all the time. There is a clear indication of this by the words when you sit, when you walk, when you lie down and when you rise up. One can infer that this is to be an every day, every week, every month, and every year occurrence. The Bible is clear where talks about parents teaching their children. Does spiritual leadership need to come from the family or can it come from somewhere else? The two locations that spiritual leadership can come from is the family or the church. The church is a great place for Spiritual leadership come from because of the amount of knowledge that most leaders in the church have. On the other hand, a family is also a great place for it to come from because; there is the sheer amount of time that they are with their children and the built in trust the children have for their parents. The question is, is the church and the family equal in terms of training or is one better than the other? When the church leads spiritually, there can be much benefit to the children. Reggie Joiner believes that, The church is a critical part of Gods divine strategy to demonstrate His redemptive story to the world.[3] Over the years, since its inception, the church has perfected the art of teaching. It has designed strategies to guide children into the knowledge of Jesus Christ. The church has specific vacation strategies called VBS, Vacation Bible School, to get the gospel into the hearts of the boys and girls. Many boys and girls give their life to Christ at the VBS. These take place all around the world. George Barna said that, Most church-going parents are neither spiritually mature nor spiritually inclined and therefore they do not have the sense of urgency or necessity about raising their kids to be spiritual champions.[4] The church has picked up the slack of parents. This is why there are becoming more and more children and youth directors. Churches are realizing that parents are not doing their God-given responsibility to lead their children spiritually. Putting it quite simply when he said, while more than four out of five parents believe they have the primary responsibility for the moral and spiritual development of their children, more than two-thirds of them abdicate that responsibility to their church. Their virtual abandonment of spiritual leadership for their children is evident in how infrequently they engage in faith-oriented activities with their young ones.[5], George Barna identified the key problem in the lives of parents today. When children come to church they are taught by educators who have spent all week learning a lesson that they will teach to the children. This lesson has been specifically planned to aid in the spiritual development of the child.ÂÂ   The Sunday school teachers, many who have done this for many years, are teaching out of the experience and other things that they have learned. This teaching becomes concentrated in i ts Biblical content. A former childrens director Michelle Anthony stated what most workers in childrens ministry feel when she said, We desire that those in our care will have been spiritually formed by the time they leave our ministry.[6] It is this desire that drives the many childrens workers at churches around the world. All this so far seems well and good, but[K2] Barna figured out the problem with this church predominant teaching. He said, So, parents are happy, children receive some religious instruction and experiences, and the churches are serving people. This sounds like a wonderful win-win situation except for one issue: the approach is completely unbiblical.[7]ÂÂ   This leads to an improper view that the church should be the primary spiritual caregivers of children. They can have an influence, but[K3] should not be the primary. When parents make the decision to lead spiritually it can have the largest impact on their children.ÂÂ   Parents have the unique,opportunity to help them (kids) discover, access, and strengthen their (kids) trust and faith in Jesus Christ[8] as authors Powell and Clark correctly identified. Children are born into this world completely helpless. They cannot do anything on their own. As they begin to grow, they become attached to their parents. They look to the parents for guidance, support, and encouragement. Through this relationship that has been God-given, the parents can use this relationship to begin guiding their children to follow Jesus Christ. As George Barna specified, Spiritual development is a lifelong continual process. It is not to be practiced as a once a week routine[K4], but a 24/7 habit.[9] This is attainable by the parents and not the church. There are 168 hours in a week. 56 of those are designated as sleeping hours. Children spend approximately 40 hours in sch ool. This leaves 78 hours of the week that the children are neither sleeping nor at school. These 78 hours can be intentional hours that parents can use to guide their children spiritually. The church only gets probably 1 to 2 hours a week of spiritual influence over the children. Powell and Clark also stated so well that parents, model an unconditional, nonjudgmental, and ever embracing love in which our kids can do nothing that jeopardizes or even lessen that love.[10] Through this parents can show pragmatically to their children that nothing can drive the kids out of the family. The parents are modeling the same that is true in Gods family. Once they are a part of Gods family, nothing they can do is able to snatch them out of the Fathers hand.[11] Parents must not wait until children are in school to begin the spiritual training of their children. They can begin as early as when they bring them home from the hospital. By simply singing the song Jesus Loves Me, parents can begin the spiritual training of their children. This song speaks great theological truths. Jesus loves me this I know for the Bible tells me so. The children can know first off that Jesus loves them. Second, they can learn to trust the Bible. It is the Bible that accurately tells them the truth that Jesus loves them.ÂÂ   The parents are teaching[K5] though the song even before the child can speak. Children can know these truths from a very young age and all it begins with is the parent singing the song to them and they are imparting deep theological truth. The authors of Losing Your Marbles plainly state, If kids dont feel loved when theyre young, they may never love themselves in a healthy way.[12] This is very easily done by parents who can model the u nconditional love that God has for us. Parents can teach their children the love of the Father with the love that they have for their kids. It is kind of ironic that God describes himself as a Father. That is what sets parenting apart from anything else. God has allowed parents to take those young individuals and be able to mold them in accordance with His Word. Jesus welcomed the little children onto His knee. He still wants kids to be with him. In their book Sticky Faith Drs. Powell and Clark say that when kids come to the conclusion through failure or pain that theyre not in control of their faith and they lose interest in their faith, they are going to set that faith aside. Parents must help the kids discover the faith that doesnt fade by staying true to the words of Jesus. They wrote the children need to learn to trust in the one the Father has sent and live convinced that the only thing that counts is faith expressing itself through love.[13] Again, Michelle Anthony brought the important truth out when she said, As ministers of Christ, I believe our job is to simply hoist our sail far and as wide as we can and catch the wind of God. That sail is important, but not as important as the wind.[14] As parents deal with children day after day they will be able to see these areas where the Holy Spirit is moving and use that prompting to speak the truth of God into the kids lives. Even a simple thing like walking down the stree t, there are areas that parents can use to teach about Gods greatness. As the children hear about news articles, parents can use that as a jumping point to speak the truth. As the parents listen for Gods direction, they will be able to use random things that can happen every single day as teaching points. Its no accident that God directly told the parents in Deuteronomy to teach the things of God, when you sit in your house and when you walk by the way and when you lie down and when you rise up.[15] These words are very strong proof that it must be the parents that lead spiritually. The church is simply not in the kids lives often enough. In conclusion, there is nothing wrong with the church teaching children spiritually[K6], but they must not be the primary. The primary spiritual leadership needs to come from the parents. They have been called by God to fulfill this role. Often parents dont know where to start[K7], but, even just reading the Bible with their kids is a great place to start. Its no coincidence that God has placed children in a family and when someone receives Jesus as their Savior they become part of Gods family. The family is very important to God and that is why the parents can reach their children best. The book Think Orange underlying theme is that the parents are red; signifying their love for the children and the church is yellow, signifying it as a light in the world. It is only when both come together, red and yellow that you get orange. Rather than the church doing one thing and the parents doing another thing, if they work together they can attack two fronts. When you combine two influences, you amplify whats important[16] The best, and most ideal situation, is the family providing the primary spiritual leadership[K8], and the church coming alongside and augmenting the parents teaching with their own teaching. The churchs role is to evangelize the world. The parents role is to disciple and train their children as spiritual leaders. This is not a task that parents can approach half-heartedly, theyÂÂ   must daily rely on the Holy Spirit to guide them in this rewarding task. Annotated Bibliography Anthony, Michelle Dreaming of More For The Next Generation Colorado Springs, Colorado: David C. Cook, 2012 Boys and girls come to Sunday School every single week and every single week, sadly, boys and girls stop coming to Sunday School. This book explores the ideas of what could happen if boys and girls, entire families, learned about got together. Imagine what could happen to our world if this generation of Christians altered their mindset about the importance of disciple in children. If an entire generation continued to practice the things that they learned in Sunday school as kids. The change can happen and it starts with parents to taking their role of spiritual leaders seriously. Anthony, Michelle; Marshman, Megan 7 Family Ministry Essentials Colorado Springs, Colorado; David C. Cook, 2015 Ministry to families has become something of an important aspect in many churches today. No longer are specific leaders just ministering to kids but, there is a gradual shift towards the church providing something for the entire family. This book looks at 7 essential aspects related to ministering to families. The first aspect is essential to this report with its title being Empowering Family as Primary. The authors suggest that in one generation there could be a shift in the primacy of parents being the primary spiritual caregivers for kids. Recycling, seatbelts, and sunscreen have changed from obscurity to necessity in only one generation. Think what could happen if we made this the prime thing we were teaching parents. Barna, George Transforming Children Into Spiritual Champions Ventura, California: Barna Research Group, Ltd., 2003 When it comes to raising boys and girls according to the word of God, George Barna leads the pack on championing this cause. He has done extensive research into reasons why children need to the number one priority in the church. He says that children need to be an investment by the church. With all the research that has been done, children are still influenced primarily by their parents. Even though churches do have an influence on children, the church is on the lowest tier of influence. Parents must rise up and take their place in leading their family spiritually. Joiner, Reggie Think Orange Colorado Springs, Colorado: David C. Cook, 2012 With the church averaging only 40 hours of a year to influence a child, compared to the 3000 that parents get, it only makes sense to have parents use that time to spiritually raise their children. The think orange philosophy is that when parents and the church work together, the spiritual training can be attacked on both fronts. Families being red, representing love and church being yellow, representing light, it is when those two combine you get orange. The author stresses that the parents voice needs to be the strongest in a kids life. The parents need to matter more than their friends, more than a coach, and more than the world. This book, if properly utilized, could change the church today, because it changes families. Joiner, Reggie; Hansen, Elizabeth; Ivy, Kristen Losing Your Marbles Cumming, Georgia: The reThink Group, Inc., 2013 Reggie Joiner weaves the tale of a boy named Simon and his quest to do the right thing at school. This book takes a look at one week out of out of Simons life and the massive changes that can take place in strictly one week. Flipping the book over, Joiner stresses that kids need six things repeatedly in their lives to make a difference. When these six things are done by parents, they can make lasting changes in their childrens lives. The six things are time over time, love over time, words over time, stories over time, tribes over time, and fun over time. These six things done over time, show children that they matter and in these parents can speak spiritually into their kids lives. Newheiser, Jim Parenting is More Than a Formula Philipsburg, New Jersey: PR Publishing Company, 2015 This book is written as an encouragement to parents that sometimes the best parenting doesnt follow strict rules. A key portion of the book is on the parental duties as directed from scripture, with the following section on responsibilities of the child for the choices that he makes. This book hits the nail on the head when it points out the very important high point that its only by Gods grace our kids can be saved. Powell, Kara E.; Clark, Chap Sticky Faith Grand Rapids, Michigan: Zondervan, 2011 This book explores the relationship between children who are raised in the church who is that walk away from it as they get older. The numbers speak of 50% of kids walking away from their faith, their faith does not stick. The essential leading factor with the decision to stay or leave the faith is the influence that parents have on the kids. The authors write that as children get older they need to have developed faith for themselves otherwise, it will not stick and they will walk away. In order to make Faith stick, parents must have conversations with their children about spiritual things throughout the week and not only on Sundays. [1] George Barna, Transforming Children Into Spiritual Champions (Ventura, California: Barna Research Group, Ltd., 2003), 61 [2] Deut. 6:6-7 (NASB) [3] Reggie Joiner, Think Orange (Colorado Springs, Colorado: David C. Cook, 2012), 36 [4] George Barna, Transforming Children Into Spiritual Champions (Ventura, California: Barna Research Group, Ltd., 2003), 111 [5] George Barna, Transforming Children Into Spiritual Champions (Ventura, California: Barna Research Group, Ltd., 2003), 109 [6] Michelle Anthony, Dreaming of More For The Next Generation (Colorado Springs, Colorado: David C. Cook, 2012), 29 [7] George Barna, Transforming Children Into Spiritual Champions (Ventura, California: Barna Research Group, Ltd., 2003), 114 [8] Kara E. Powell and Chap Clark, Sticky Faith (Grand Rapids, Michigan: Zondervan, 2011), 37 [9] George Barna, Transforming Children Into Spiritual Champions (Ventura, California: Barna Research Group, Ltd., 2003), 116 [10] Ibid. [11] John 10:29 (NASB) [12] Reggie Joiner, Elizabeth Hansen, Kristen, Losing Your Marbles (Cumming, Georgia: The reThink Group, Inc., 2013), 47 [13] Kara E. Powell and Chap Clark, Sticky Faith (Grand Rapids, Michigan: Zondervan, 2011), 36 [14] Michelle Anthony, Megan Marshman, 7 Family Ministry Essentials )Colorado Springs, Colorado; David C. Cook, 2015), 121 [15] Deut. 6:6-7 (NASB) [16] Reggie Joiner, Think Orange (Colorado Springs, Colorado: David C. Cook, 2012), 134 [K1]comma [K2]comma [K3]comma [K4]comma [K5]awkward sentence [K6]comma [K7]comma here instead [K8]comma

Fully Connected Mesh Topology Information Technology Essay

Fully Connected Mesh Topology Information Technology Essay These five labels describe how the devices in a network are interconnected rather than their physical arrangement. For example, having a star topology does not mean that all of the computers in the network must be placed physically around a hub in a star shape. A consideration when choosing a topology is the relative status of the devices be linked. Two relationships are possible: peer-to-peer, where the devices share the link equally, and primary-secondary, where one device controls traffic and the others must transmit through it. Ring and mesh topologies are more convenient for peer-to-peer transmission, while star and tree are more convenient for primary-secondary, bus topology is equally convenient for either. Mesh In a mesh topology, every device has a dedicated point-to-point link to every other device. The term dedicated means that the link carries traffic only between the two devices it connects. A fully connected mesh network therefore has n*(n l)/2 physical channels to link n devices. To accommodate that many links, every device on the network must have 7 input/output (I/O) ports. tifsTmp9.tif Figure (9) Fully Connected Mesh Topology A mesh offers several advantages over other network topologies. First, the use of dedicated links guarantees that each connection can carry its own data load, thus eliminating the traffic problems that can occur when links must be shared by multiple devices. Second, a mesh topology is robust. If one link becomes unusable, it does not incapacitate the entire system. Another advantage is privacy or security. When every message sent travels along dedicated line, only the intended recipient sees it. Physical boundaries prevent other users from gaining access to messages. Finally, point-to-point links make fault identification and fault isolation easy. Traffic can be routed to avoid links with suspected problems. This facility enables the network manager to discover the precise location of the fault and aids in finding its cause and solution. The main disadvantages of a mesh are related to the amount of cabling and the number of I/O ports required. First, because every device must be connected to ever other device, installation and reconfiguration are difficult. Second, the sheer bulk of the wiring can be greater than the available space (in walls, ceilings, or floors) can accommodate. And, finally, the hardware required connecting each link (I/O ports and cable can be prohibitively expensive). For these reasons a mesh topology is usually implemented in a limited fashionà ¢Ãƒ ¢Ã¢â‚¬Å¡Ã‚ ¬for example, as a backbone connecting the main computers of a hybrid network that can include several other topologies. Star In a star topology, each device has a dedicated point-to-point link only to a central controller, usually called a hub. The devices are not directly linked to each other. Unlike a mesh topology, a star topology does not allow direct traffic between devices. The controller acts as an exchange. If one device wants to send data to another, it sends the data to the controller, which then relays the data to the other connected device. HubtifsTmp10.tif Figure (10) Star topology A star topology is less expensive than a mesh topology. In a star, each device needs only one link and one I/O port to connect it to any number of others. This factor also makes it easy to install and reconfigure. Far less cabling needs to be housed, and additions, moves, and deletions involve only one connection: between that device and the hub. Other advantages include robustness. If one link fails, only that link is affected. All other links remain active. This factor also lends itself to easy fault identification and fault isolation. As long as the hub is working, it can be used to monitor link problems and bypass defective links. However, although a star requires far less cable than a mesh, each node must be linked to a central hub. For this reason more cabling is required in a star than in some other topologies (such as tree, ring, or bus). Tree A tree topology is a variation of a star. As in a star, nodes in a tree are linked to a central hub that controls the traffic to the network. However, not every device plugs directly into the central hub. The majority of devices connect to a secondary hub that in turn is connected to the central hub. The central hub in the tree is an active hub. An active hub contains a repeater, which is a hardware device that regenerates the received bit patterns before sending them out. Repeating strengthens trans- missions and increases the distance a signal can travel. tifsTmp11.tif Figure (11) Tree Topology The secondary hubs may be active or passive hubs. A passive hub provides a simple physical connection between the attached devices. The advantages and disadvantages of a tree topology are generally the same as those of a star. The addition of secondary hubs, however, brings two further advantages. First, it allows more devices to be attached to a single central hub and can therefore increase the distance a signal can travel between devices. Second, it allows the network to isolate and prioritize communications from different computers. For example, the computers attached to one secondary hub can be given priority over computers attached to another secondary hub. In this way, the network designers and operator can guarantee that time-sensitive data will not have to wait for access to the network. A good example of tree topology can be seen in cable TV technology where the main cable from the main office is divided into main branches and each branch is divided into smaller branches and so on. The hubs are used when a cable is divided. Bus The preceding examples all describe point-to-point configurations. A bus topology, on the other hand, is multipoint. One long cable acts as a backbone to link all the devices in the network. Nodes are connected to the bus cable by drop lines and taps. A drop line is a connection running between the device and the main cable. A tap is a connector that either splices into the main cable or punctures the sheathing of a cable to create a contact with the metallic core. As a signal travels along the backbone, some of its energy is transformed into heat. Therefore, it becomes weaker and weaker the farther it has to travel. For this reason there is a limit on the number of taps a bus can support and on the distance between those taps. Advantages of a bus topology include ease of installation. Backbone cable can be laid along the most efficient path, then connected to the nodes by drop lines of various lengths. In this way, a bus uses less cabling than mesh, star, or tree topologies. In a star, for example, four network devices in the same room require four lengths of cable reaching all the way to the hub. In a bus, this redundancy is eliminated. Only the backbone cable stretches through the entire facility. Each drop line has to reach only as far as the nearest point on the backbone. tifsTmp12.tif Figure (12) Bus Topology Disadvantages include difficult reconfiguration and fault isolation. A bus is usually designed to be optimally efficient at installation. It can therefore be difficult to add new devices. As mentioned above, signal reflection at the taps can cause degradation in quality. This degradation can be controlled by limiting the number and spacing of devices connected to a given length of cable. Adding new devices may therefore require modification or replacement of the backbone. In addition, a fault or break in the bus cable stops all transmission, even between devices on the same side of the problem. The damaged area reflects signals back in the direction of origin, creating noise in both directions. Ring In a ring topology, each device has a dedicated point-to-point line configuration only with the two devices on either side of it. A signal is passed along the ring in one direction, from device to device, until it reaches its destination. Each device in the ring incorporates a repeater. When a device receives a signal intended for another device, its repeater regenerates the bits and passes them along. A ring is relatively easy to install and reconfigure. Each device is linked only to its immediate neighbors (either physically or logically). To add or delete a device requires moving only two connections. The only constraints are media and traffic considerations (maximum ring length and number of devices). In addition, fault isolation is simplified. Generally in a ring, a signal is circulating at all times. If one device does not receive a signal within a specified period, it can issue an alarm. The alarm alerts the network operator to the problem and its location. However, unidirectional traffic can be a disadvantage. In a simple ring, a break in the ring (such as a disabled station) can disable the entire network. This weakness can be solved by using a dual ring or a switch capable of closing off the break. tifsTemp 13.a.tif Figure (13) Ring Topology OSI Model This model is based on a proposal developed by the International Standards Organization (ISO) as a first step toward international standardization of the protocols used in the various layers. The model is called the ISO-OSI (Open Systems Interconnection) Reference Model because it deals with connecting open systemsà ¢Ãƒ ¢Ã¢â‚¬Å¡Ã‚ ¬that is, systems that are open for communication with other systems. We will usually just call it the OSI model for short. The OSI model has seven layers. The principles that were applied to arrive at the seven layers are as follows 1. A layer should be created where a different level of abstraction is needed. 2. Each layer should perform a well-defined function. 3. The function of each layer should be chosen with an eye toward defining internationally standardized protocols. 4. The layer boundaries should be chosen to minimize the information flow across the interfaces. 5. The number of layers should be large enough that distinct functions need not be thrown together in the same layer out of necessity, and small enough that the architecture does not become unwieldy. Below we will discuss each layer of the model in turn, starting at the bottom layer. Note that the OSI model itself is not network architecture because it does not specify the exact services and protocols to be used in each layer. It just tells what each layer should do. However, ISO has also produced standards for all the layers, although these are not part of the reference model itself. Each one has been published as a separate international standard. tifsTmp2-a.tif Figure (16) The OSI Reference Model The Physical Layer The physical layer is concerned with transmitting raw bits over a communication channel. The design issues have to do with making sure that when one side sends a 1 bit, it is received by the other side as a 1 bit, not as a 0 bit. Typical questions here are how many volts should be used to represent a 1 and how many for a 0, how many microseconds a bit lasts, whether transmission may proceed simultaneously in both directions, how the initial connection is established and how it is torn down when both sides are finished, and how many pins the network connector has and what each pin is used for. The design issues here largely deal with mechanical, electrical, and procedural interfaces, and the physical transmission medium, which lies below the physical layer. The Data Link Layer The main task of the data link layer is to take a raw transmission facility and transform it into a line that appears free of undetected transmission errors to the network layer. It accomplishes this task by having the sender break the input data up into data frames (typically a few hundred or a few thousand bytes), transmit the frames sequentially, and process the acknowledgement frames sent back by the receiver. Since the physical layer merely accepts and transmits a stream of bits without any regard to meaning or structure, it is up to the data link layer to create and recognize frame boundaries. This can be accomplished by attaching special bit patterns to the beginning and end of the frame. If these bit patterns can accidentally occur in the data, special care must be taken to make sure these patterns are not incorrectly interpreted as frame delimiters. A noise burst on the line can destroy a frame completely. In this case, the data link layer software on the source machine can retransmit the frame. However, multiple transmissions of the same frame introduce the possibility of duplicate frames. A duplicate frame could be sent if the acknowledgement frame from the receiver back to the sender were lost. It is up to this layer to solve the problems caused by damaged, lost, and duplicate frames. The data link layer may offer several different service classes to the network layer, each of a different quality and with a different price. Another issue that arises in the data link layer (and most of the higher layers is well) is how to keep a fast transmitter from drowning a slow receiver in data. Some traffic regulation mechanism must be employed to let the transmitter know how much buffer space the receiver has at the moment. Frequently, this flow regulation and the error handling are integrated. If the line can be used to transmit data in both directions, this introduces a new complication that the data link layer software must deal with. The problem is that the acknowledgement frames for A to B traffic compete for the use of the line with data frames for the B to A traffic. Broadcast networks have an additional issue in the data link layer to control access to the shared channel. A special, sub layer of the data link layer, the medium access sub layer, deals with this problem. The Network Layer The network layer is concerned with controlling the operation of the subnet. A key design issue is determining how packets are routed from source to destination. Routes can be based on static tables that are wired into the network and rarely changed. They can also be determined at the start of each conversation, for example a terminal session. Finally, they can be highly dynamic, being determined anew for each packet, to reflect the current network load. If too many packets are present in the subnet at the same time, they will get in each others way, forming bottlenecks. The control of such congestion also belongs to the network layer. Since the operators of the subnet may well expect remuneration for their efforts, there is often some accounting function built into the network layer. At the very least, the software must count how many packets or each customer sends characters or bits, to produce billing information. When a packet crosses a national border, with different rates on each side, the accounting can become complicated. When a packet has to travel from one network to another to get to its destination, many problems can arise. The addressing used by the second network may be different from the first one. The second one may not accept the packet at all because it is too large. The protocols may differ, and so on. It is up to the network layer to overcome all these problems to allow heterogeneous networks to be interconnected. In broadcast networks, the routing problem is simple, so the network layer is often thin or even nonexistent. The Transport Layer The basic function of the transport layer is to accept data from the session layer, split it up into smaller units if need be, pass these to the network layer, and ensure that the pieces all arrive correctly at the other end. Furthermore, all this must be done efficiently, and in a way that isolates the upper layers from the inevitable changes in the hardware technology. Under normal conditions, the transport layer creates a distinct network connection for each transport connection required by the session layer. If the transport connection requires a high throughput, however, the transport layer might create multiple network connections, dividing the data among the network connections to improve throughput. On the other hand, if creating or maintaining a network connection is expensive, the transport layer might multiplex several transport connections onto the same network connection to reduce the cost. In all cases, the transport layer is required to make the multiplexing transparent to the session layer. The transport layer also determines what type of service to provide the session layer, and ultimately, the users of the network. The most popular type of transport connection is an error-free point-to-point channel that delivers messages or bytes in the order in which they were sent. However, other possible kinds of transport service are transport of isolated messages with no guarantee about the order of delivery, and broadcasting of messages to multiple destinations. The type of service is determined when the connection is established. The transport layer is a true end-to-end layer, from source to destination, in other words, a program on the source machine carries on a conversation with a similar program on the destination machine, using the message headers and control messages. In the lower layers, the protocols are between each machine and its immediate neighbors, and not by the ultimate source and destination machines, which may be separated by many routers. There is a difference between layers 1 through 3, which are chained, and layers 4 through 7, which are end-to-end. Many hosts are multi-programmed, which implies that multiple connections will be entering and leaving each host. Their needs to be some way to tell which message belong to which connection. The transport header is one place this information can be put. In addition to multiplexing several message streams onto one channel, the transport layer must take care of establishing and deleting connections across the network. This requires some kind of naming mechanism, so that a process on one machine has a way of describing with whom it wishes to converse. There must also be a mechanism to regulate the flow of information, so that a fast host cannot overrun a slow one. Such a mechanism is called flow control and plays a key role in the transport layer (also in other layers). Flow control between hosts is distinct from flow control between routers, although we will later see that similar principles apply to both. The Session Layer The session layer allows users on different machines to establish sessions between them. A session allows ordinary data transport, as does the transport layer, but it also provides enhanced services useful in some applications. A session might be used to allow a user to log into a remote timesharing system or to transfer a file between two machines. One of the services of the session layer is to manage dialogue control. Sessions can allow traffic to go in both directions at the same time, or in only one direction at a time. If traffic can only go one way at a time (analogous to a single railroad track), the session layer can help keep track of whose turn it is. A related session service is token management. For some protocols, it is essential that both sides do not attempt the same operation at the same time. To manage these activities, the session layer provides tokens that can be exchanged. Only the side holding the token may perform the critical operation. Another session service is synchronization. Consider the problems that might occur when trying to do a 2-hour file transfer between two machines with a 1-hour mean time between crashes. After each transfer was aborted, the whole transfer would have to start over again and would probably fail again the next time as well. To eliminate this problem, the session layer provides a way to insert checkpoints into the data stream, so that after a crash, only the data transferred after the last checkpoint have to be repeated. The Presentation Layer The presentation layer performs certain functions that are requested sufficiently often to warrant finding a general solution for them, rather than letting each user solve the problems. In particular, unlike all the lower layers, which are just interested in moving bits reliably from here to there, the presentation layer is concerned with the syntax and semantics of the information transmitted. A typical example of a presentation service is encoding data in a standard agreed upon way. Most user programs do not exchange random binary bit strings. They exchange things such as peoples names, dates, amounts of money, and invoices. These items are represented as character strings, integers, floating-point numbers, and data structures composed of several simpler items. Different computers have different codes for representing character strings, integers, and so on. In order to make it possible for computers with different representations to communicate, the data structures to be exchanged can be defined in an abstract way, along with a standard encoding to be used on the wire. The presentation layer manages these abstract data structures and converts from the representation used inside the computer to the network standard representation and back. The Application Layer The application layer contains a variety of protocols that are commonly needed. For example, there are hundreds of incompatible terminal types in the world. Consider, the plight of a full screen editor that is supposed to work over a network with many different terminal types, each with different screen layouts, escape sequences for inserting and deleting text, involving the cursor, etc. One way to solve this problem is to define an abstract network virtual terminal that editors and other programs can be written to deal with. To handle each terminal type, a piece of software must be written to map the functions of the network virtual terminal onto the real terminal. For example, when the editor moves the virtual terminals cursor to the upper left-hand corner of the screen, this software must issue the proper command sequence to the real terminal to get its cursor there too. All the virtual terminal software is in the application layer. Another application layer function is file transfer. Different file systems have different file naming conventions, different ways of representing text lines, and so on. Transferring a file between two different systems requires handling these and other incompatibilities. This work, too, belongs to the application layer, as do electronic mail, remote job entry, directory lookup, and various other general purpose and special-purpose facilities.