The History Iran Sanctions - 1979 Through 2017

Although the United States imposed sanctions against Iran for decades, none levered the country into compliance with international rules regarding terrorism or nuclear energy. By early 2012, however, evidence appeared to be mounting that sanctions by both the U.S. and its global allies were hurting Iran. The Joint Comprehensive Plan of Action went into effect in 2015, easing tensions and sanctions considerably. Most of the sanctions cut into Irans oil exports, which account for 85 percent of the countrys export revenue. Irans repeated threats to close the Strait of Hormuz, a vital oil conduit, to international use indicated at one point that Iran was kicking at global oil usage to relieve pressure on its own oil industry. The Carter Years Islamic radicals captured 52 Americans at the U.S. Embassy in Tehran and held them hostage for 444 days beginning in November 1979. U.S. President Jimmy Carter tried unsuccessfully to free them, including authorizing a military rescue attempt. Iranians did not free the hostages until just after Ronald Reagan replaced Carter as president on January 20, 1981. The United States broke diplomatic relations with Iran in 1980 in the midst of that crisis. The U.S. also levied its first round of sanctions against Iran during this time. Carter banned imports of Iranian oil, froze some $12 billion in Iranian assets in the U.S. and later banned all U.S. trade with and travel to Iran in 1980. The U.S. lifted the embargoes after Iran released the hostages. Sanctions Under Reagan The Reagan Administration declared Iran a state sponsor of terrorism in 1983. As such, the U.S. opposed international loans to Iran. When Iran began threatening traffic through the Persian Gulf and Strait of Hormuz in 1987, Reagan authorized naval escorts for civilian ships and signed a new embargo against Iranian imports. The United States also banned the sale of dual-use items to Iran – civilian goods with the possibility of military adaptation. The Clinton Years President Bill Clinton expanded U.S. sanctions against Iran in 1995. Iran was still labeled a state sponsor of terrorism and President Clinton took this action amid widespread fear it was pursuing weapons of mass destruction. He prohibited all American involvement with the Iranian petroleum industry. He banned all American investment in Iran in 1997, as well as what little U.S. trade remained with the country. Clinton also encouraged other countries to do the same. Sanctions Under George W. Bush The United States repeatedly froze the assets of people, groups or businesses identified as helping Iran sponsor terrorism under President George W. Bush, as well as those perceived as supporting Irans efforts to destabilize Iraq. The U.S. also froze the assets of foreign entities believed to be helping Iran in those areas. The United States  also banned so-called U-turn financial transfers involving Iran. According to the U.S. Treasury Department, a U-turn transfer involves Iran but originates and ends with non-Iranian foreign banks. Obamas Sanctions of Iran President Barack Obama has been strident with Iranian sanctions. He banned some imports of Iranian foodstuffs and carpets in 2010, and Congress also allowed him to tighten Iranian sanctions with the Comprehensive Iran Sanctions, Accountability, and Divestment Act (CISADA). Obama could encourage non-U.S. petroleum firms to halt the sale of gasoline to Iran, which has poor refineries. It imports nearly one-third of its gasoline. The CISADA also prohibited foreign entities from using American banks if they do business with Iran. The Obama Administration sanctioned Venezuelas nationalized oil company for trading with Iran in May 2011. Venezuela and Iran are close allies. Iranian President Mahmoud Ahmadinejad traveled to Venezuela in early January 2012 to meet with President Hugo Chavez, in part  about the sanctions. In June 2011, the Treasury Department announced new sanctions against Irans Revolutionary Guard (already named in other sanctions), the Basij Resistance Force, and Iranian law enforcement entities. Obama ended 2011 by signing a defense funding bill that would allow the U.S. to cease dealing with financial institutions that do business with Irans central bank. The bills sanctions took effect between February and June 2012. Obama was given the power to waive aspects of the bill if implementation would hurt the U.S. economy. It was feared that limiting access to Iranian oil would drive up gasoline prices. The Joint Comprehensive Plan of Action Six world powers joined together in 2013 to negotiate with Iran, offering relief from some sanctions if Iran would cease its nuclear efforts. Russia, Britain, Germany, France, and China joined the U.S. in this effort, which finally resulted in an agreement in 2015. Then came the prisoner swap in 2016, with the U.S. exchanging seven imprisoned Iranians in exchange for Iran releasing five Americans it was holding. The U.S. lifted its sanctions against Iran under President Obama in 2016.   President Donald J. Trump President Trump announced in April 2017 that his administration intends to review the countrys history of sanctions against Iran. Although many feared this would potentially eradicate the terms of the 2015 deal due to Irans continued support of terrorism, the review was, in fact, provided for and mandatory under the terms of the 2015 pact.

The Assassination Of Julius Caesar - 1516 Words

His name is Brutus he lives in the deepest part of Hell right next to Satan himself, he had betrayed his closest friend and for that he resides in the coldest part of Satan s kingdom. He is one of three of Satan s apprentices the son, father and holy spirit. He is in the ninth circle of hell for his betrayal against the state of Rome, which ultimately lead to the fall of Rome. He was one of the main conspirators in helping in the assassination of Julius Caesar. His sins have landed him in the most treacherous part of hell where he will be thinking about his actions for an eternity. Brutus was born in Macedonia 85 BCE. He had a happy childhood with a positive upbringing. Brutus had a wealthy family so his next meal or clothes were never a problem, he lived in the lap of luxury for a large portion of his life. As Brutus got older he dreamed of being a king or a general, he just wanted to have power. He decided to join the Roman army and he made his way up the ranks fast because of family ties he had throughout the military. After only a few years in the army Brutus became a general and his dream had finally came true. He began conquering land and fighting in many battles. After countless victories, Brutus started to become very bored, and his fellow general Julius Caesar was making more of a name for himself. Brutus became very jealous of Julius because he strived to be the best at everything, even if he was surpassing a good friend s achievements. As time passed byShow MoreRelatedThe Assassination of Julius Caesar1325 Words   |  6 Pagesstrength to fear, dictatorship, and voraciousness. These powerful aristocrats were emperors, sat on the top of Rome’s social order, but many of these emperors abused their status and ability. Roman emperors’ history was all mixed ingredients of love, assassination, vengeance, terror, voracity, jealousy, and haughtiness. The first century AD of the Roman Empire became a perilous period of imperialism because hereditary rule. Emperors in this epoch were not selected based on their skill and trustworthinessRead MoreThe Assassination of Julius Caesar1768 Words   |  8 Pages Wendy Voong History 101 J.Duran 24 October 2014 The Assassination of Julius Caesar â€Å"The Assassination of Julius Caesar† by Michael Parenti goes into details about the events that lead up to the death of Caesar due to class conflicts. In 44 BC, the assassination of Julius Caesar was lead by conspiring members of the Roman senate who wanted to remove the dictator, who was increasingly acquiring power, and to revive the Republic government. Parentis book protestsRead MoreThe Assassination of Julius Caesar1213 Words   |  5 PagesOn the Ides of March one of the most famous assassinations took place; the assassination of the leader of the Roman republic, Julius Caesar. The death of Julius Caesar allowed Gaius Julius Octavius who would later be given the title Augustus by the senate, to enter the political realm of Rome by accepting his inherited power. But before Augustus could gain any control in Rome he had to defeat his opposition, Mark Antony who also sought to gain control of Rome at the time. Augustus managed to defeatRead MoreThe Assassination of Ju lius Caesar Essay1528 Words   |  7 PagesThe Assassination of Julius Caesar The assassination of Julius Caesar in 44BC by conspiring members of the Roman senate was an effort to remove a dictator whose power had grown to extraordinary levels and to revive the Republic government. Caesar’s power span throughout the entire Roman Empire, which during his reign extended from present day Syria, down into parts of Africa, over to Spain, most of France and all of Italy. He had the favor of the people, military and most of the Roman governmentRead MoreThe Assassination Of Julius Caesar As A Roman Dictator1086 Words   |  5 PagesJulius Caesar was a Roman Dictator who was both loved and hated by those that he ruled over. Throughout the world, he has been written about in a variety of different ways and is portrayed as a politician as well as a selfish dictator. Three â€Å"firsthand† accounts that were written to give us a better understanding of Julius Caesar were â€Å"The Assassination of Julius Caesar†, â€Å"Tranquillus, Gaius Suetoniusà ¢â‚¬ , and â€Å"Plutarch, The Assassination of Julius Caesar, from Marcus Brutus†. We will explore the writingsRead MoreThe Assassination Of Julius Caesar By Michael Parenti961 Words   |  4 PagesNicholas Okada 10/21/14 APWH Period 4 Book Review: The Assassination of Julius Caesar by Michael Parenti In The Assassination of Julius Caesar, Michael Parenti highlights the many significant people and events that characterized the late Roman Republic. Specifically, he focuses on the time period between the election of Tiberius Grachus, to the rise of Augustus, the first emperor of Rome. In this account of history, Parenti presents the social, political, and economic aspects of the Roman cultureRead MoreJulius Caesar s Assassination On Rome, Politically And Socially1717 Words   |  7 PagesThis investigation evaluates the question, to what extent did Julius Caesar s assassination affect Rome, politically and socially. Gaius Julius Caesar, famously known for his brilliant military strategies and shrewd political expertise, helped transform the Roman Republic into one of the greatest civilization in the western world. During his reign, Julius Ceasar expanded Rome’s geographical territory across Ancient Europe immensely, conquering areas of present-day France and Britain. The i nvestigationRead MoreJustification of Caesar’s Assassination in Shakespeares The Tragedy of Julius Caesar878 Words   |  3 PagesWilliam Shakespeare, wrote the play The Tragedy of Julius Caesar. The story takes place toward the end of the Roman Republic in 44 BC in Ancient Rome. The play follows the words and actions of the Roman senators, plebeians and their emperor Julius Caesar. As the story begins, readers find out the many of the senators are not pleased with Caesar as a ruler of the Roman people. Two characters, Brutus and Cassius are especially passionate about killing Caesar to end his rule. Through discussing plans andRead MoreGaius Cassius Longinu Part in the Assissination of Julius Ceasar797 Words   |  3 PagesCassius, full name Gaius Cassius Longinus, was recalled as a good soldier with a terrible temper and in politics, irrational and drowned by vanity. In his time he was a Roman senator, also known by his part-taking in the assassination of Julius Caesar. In his early years, he studied philosophy under Archelaus, and was fluent in Greek. His wife, Junia Tertia was the half-sister of co-conspirator Brutus. Cassius served under Crassus, He took part in saving Remnants of the Roman army against theRead MoreJulius Caesar ´s Death: Analysis Essay552 Words   |  3 PagesShould Julius Caesar have been killed? This question has plagued history for years without a real answer. Julius Caesar was corrupt and all powerful, and his death saved Rome. It really is that simple; he declared himself dictator for life and ignored the Senate’s power. A man with that much power can only hurt a nation. Julius Caesar was a blood thirsty man. He fought everyone he could just to extend Rome. (Julius Caesar. ) He savagely killed anyone that got in his way. Many may say that he was

Ethylene Oxide (EtO)

Questions: 1. Define the characteristics of ethylene oxide2. Define the characteristics of ethylene oxide covering toxicological effects and physiologic effects3. Discuss the OSHA exposure standards, personal protection equipments and correct sampling process for ethylene oxide. Answers: Introduction Ethylene Oxide (EtO) is a colorless, flammable gas that smells like ether at toxic levels. EtO is workable gas for many industrial and commercial purposes as intermediate, fumigant and sterilant of medical equipments. However, with potential utility characteristics, this gas also persist potential hazardous characteristics. As employees working in medical premises it is important to get knowledge on these characteristics of EtO as well as the process to minimise its hazardous outcomes of EtO sterilisation machine (Reichert Young, 1997, p.34). As a safety officer, Mr. Roy Whittaker has constructed this short description of essential data or information that employees at Blackheath Community Hospital need to know regarding new Ethylene Oxide Sterilization Machine to be installed in the organization. 1. Defining the characteristics of ethylene oxide The following are some of the most important characteristics of EtO sterilisation machine that every employee should know: - The EtO exposure rate is limited to a part of the million air parts and is measured as TWA that is 8-hour time-weighted average. The short-term exposure limit for EtO is 5 ppm for average sampling time of 15 minutes that is known as permissible exposure limits (PELs) The action level is calculated as per 8-hour TWA for employee exposure as threshold limit as per these standards. The OSHA standards provide knowledge on EtO occupational exposure, handling of materials containing EtO and processing protocol (Ackert-Burr, 2010, p. 285). 2. Defining the characteristics of ethylene oxide covering toxicological effects and physiologic effects Physiological effects The mild effects of EtO include irritation in eyes, skin, dermal and respiratory tract. Anaphylaxis Type-1 and Contact dermatitis Type -4 along with occupational asthma is commonly observed in people with EtO exposure. The common disease resulting due to the toxicology of EtO includes blurred eye, blisters, dizziness, nausea, vomiting, headache, and convulsions. The reproductive effects of EtO involve risk conditions in pregnancy as well as chances of abortion in women (Arnold et al. 2011). The neurological effects of ethylene oxide involve a major effect on the central nervous system. These are reports indicating the development of axonal degeneration as well as defects in the myelin sheath of the brain due to EtO exposure 1300mg. Genetic effects of gas involve an increase in chromosomal materials like chromatin material, lymphocytes and micronuclei. Breakage in genetic material DNA can also occur due to EtO exposure. EtO is also capable of generating carcinogenic effect giving birth to different cancers like leukaemia, Stomach, pancreases, haematopoietic, brain cancer etc. (Lewis et al. 2003). Toxicological effects Ethylene oxide causes toxicity by inhalation above the TWA limits leading to irritation in mucous membranes of throat and nose. EtO toxicology is known as acute poisoning. A bit higher toxicity of EtO can lead to trachea and bronchi damages as well as partial lung collapse. The occurrence of pulmonary oedema and cardiovascular damages are observed in the case of long-term ethylene oxide exposure of minimum 72 hours (Toxicological profile for ethylene oxide, 2016). 3. Discussing the OSHA exposure standards, personal protection equipments and correct sampling process for ethylene oxide OSHA exposure standards The following are OSHA exposure standards for employee collected from (OSHA factsheet, 2016). As discussed above the TWA level of ethylene oxide exposure the activities like air monitoring, medical examinations, training and labelling should be completed within this threshold time limit. The employees cannot release airborne EtO concentrations at of above the mentioned action level under normal circumstances If the employee exceeds the PEL level to ethylene oxide exposure than they should follow the required actions to avoid risk. Use of work practice and engineering controls mentioned in OSHA standards are recommended to control the exposure of ethylene oxide. The personal, area and leak monitoring are keen requirements to be performed for EtO exposure Employees should follow the written compliance program developed to reduce exposure risk of EtO Establish a specific area that allows Eto exposure above the threshold limit time that is named as leak area restricted for specific use Employee should strictly follow personal monitoring protocol as per OSHA standards to tackle this exposure The medical surveillance program is mentioned as keen requirement to be established in the organization to monitor employee exposure and risk Try to maintain employee rotation as per 8-hour TWA exposure limit time Provide warning labels on equipments or containers that cause high EtO exposure Select, maintain and provide personal protection equipments for the personal safety of the employee. Maintain initial and periodic monitoring of employee on regular basis to detect exposure rate Additional monitoring should be processed for any change in workplace conditions Medical surveillance compulsory for employee assigned in high exposure area and emergency EtO exposure above TWA level Maintain material safety data sheet as per OSHA hazard communication standards Maintain employee medical record and EtO exposure record for 30 days Provide medical aid and doctor facility for emergency conditions Do not allow drink, smoke or feeding in EtO zone (Small business guide for Ethylene oxide, 2016). Personal protection equipments The personal protective equipments (PPE) as per OSHA standards for getting protection from EtO are described below: - For eye and face protection the use of safety spectacles, goggles, laser safety goggles and face shields while handling EtO exposures. For body protection from EtO, the clotting material made from rubber, neoprene, plastics and rubberized fabrics provides protection from ethylene oxide. For the protection of respiratory system, the use of positive-pressure supplied air OSHA recommends equipment for employees dealing with EtO exposure. The use of full-face respirator is highly recommended by OSHA Keep first aid for personal protection during long-term EtO exposure (OSHA factsheet, 2016) Sampling process as per OSHA standards The sampling process as per OSHA standards for collecting EtO involves the use of charcoal tubes and sampling pumps that are followed by gas chromatography analysis. The process starts by desorbing charcoal tubes in 1% CS(2) benzene. Further, the sample is derivatized with hydrogen bromide or carbon disulphide followed by sodium carbonate treatment. The below provided are specific requirements of the sampling process. Air volume- 1 litre Sampling rate 0.05Lpm Detection limit based on mentioned air volume 13.3 ppb Estimate of Standard error 6.59 % Reliable quantitation limit 52.2 ppb Special requirements The provided sample should be analysed within 15 days of sampling date. This sampling process is convenient, sensitive and reproducible to allow proper analysis of Ethylene oxide. The reanalysis of this sample is also recommended and possible as per OSHA standards. The longer GC retention time reduces interferences in this sampling process of Ethylene oxide (Sampling and analytical methods for ethylene oxide (Non-mandatory) - 1910.1047 App D, 2016) Brief training program This training program for the employees will include a training session to demonstrate the process and techniques that employee need to follow regarding the handling of ethylene oxide machinery followed by a demonstration on OSHA standards and guidelines. After this employee will be provided with a training session regarding the management and protection techniques for using sterilisation machinery. The medical record of all the employees will be recorded for further processes after the training session. References Books Reichert, M., Young, J. H. (1997).Sterilization technology for the health care facility. Jones Bartlett Learning. Journals Ackert-Burr, C. (2010). Low-Temperature Sterilization: Are You In the Know?.Perioperative Nursing Clinics,5(3), 281-290. Arnold, E. V., Doletski, B. G., Dunn, T. M., Raulli, R. E., Mueller, E. P., Benedek, K. R., Murville, M. L. (2011).U.S. Patent No. 8,017,074. Washington, DC: U.S. Patent and Trademark Office. Lewis, M., Meek, M. E., Liteplo, R. G., World Health Organization. (2003). Ethylene oxide. OSHA factsheet. (2016). Retrieved 13 July 2016, from https://www.osha.gov/OshDoc/data_General_Facts/ethylene-oxide-factsheet.pdf Sampling and analytical methods for ethylene oxide (Non-mandatory) - 1910.1047 App D. (2016). Osha.gov. Retrieved 13 July 2016, from https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDSp_id=10074 Small business guide for Ethylene oxide. (2016). Retrieved 13 July 2016, from https://www.osha.gov/Publications/ethylene-oxide.pdf Toxicological profile for ethylene oxide. (2016). Retrieved 13 July 2016, from https://www.atsdr.cdc.gov/TOXPROFILES/TP137.PDF

The factors affecting tensile strength Essay Example

The factors affecting tensile strength Paper I am comparing four sets of data. My data will be categorical. There is a simple statistical test which looks at the difference between observed and expected values and relates them to a probability level, thus making it possible to identify how likely it is that the values are significantly different. This test is called the Chi squared test. Precautions to ensure reliability   We are assuming ethnic background does not affect our results. It will not cause a massive variation in our conclusion.   All hair samples must be taken from 16-18 year old females. 6 different samples must be taken for each colour of hair. Make sure all equipment is set up; ensuring the strand of hair is fastened to the shown equipment correctly. (Figure 5). * Each hair is tested five times, so I am repeating the experiment, to make my results reliable and more accurate. Results (My own (raw data) results will be highlighted in dark red on tables 2, 3, 4 5). (The letter B is used in my results to show where the hair broke). Investigating the factors affecting tensile strength of human hair Analysing: (Skill C) Calculations Strength is determined by the amount of stress a hair can withstand without breaking. To work out the strength of each hair I calculated the stress applied to each when breaking. To do all the calculations I used the following formulas: 1  I calculated my values to do the statistical test. Discussion Melanin molecules are proteins, which are produced at the root of each hair. The more melanin in your hair, the darker it will get. An amino acid called tyrosine is converted into melanin so the hair will have colour. First, the bodys blood vessels carry tyrosine to the bottom of each hair follicle. Then, in this melanin factory tyrosine is used as the raw material for the production of the natural melanin that is the colour in hair. We will write a custom essay sample on The factors affecting tensile strength specifically for you for only $16.38 $13.9/page Order now We will write a custom essay sample on The factors affecting tensile strength specifically for you FOR ONLY $16.38 $13.9/page Hire Writer We will write a custom essay sample on The factors affecting tensile strength specifically for you FOR ONLY $16.38 $13.9/page Hire Writer In short, natural hair colour depends upon the presence, amount and distribution of melanin, a natural pigment found in the cortex. All natural hair colours are created from two types of melanin. Eumelanin = black pigment Pheomelanin = red/yellow pigment Mixed melanins = when both eumelanin and pheomelanin mix together inside one melanin granule. The natural colour of the hair is decided by: a) What type of melanin is in the hair b) How much melanin is in the hair c) How closely packed or scattered the melanin is within the cortex. The type of melanin and the size of the granules determine whether hair will be brown, blonde, ginger or black. The amount of melanin and its distribution determine how dark or light the hair colour will be. Black hair is created from granules full of eumelanin densely packed in the hairs cortex. Brown hair, depending on its cool or warm tones and its darkness or lightness, is created either from granules filled with eumelanin and more sparsely distributed along the cortex than those of black hair, or granules filled with a blend of mixed melanins. The red/yellow pheomelanin is believed to cause the warm, golden, or auburn tones found in most brown hair. Blonde hair has a very low melanin content. And while scientists have not yet determined which is dominant, it is believed that eumelanin creates blonde hair. Melanin in blonde hair is so sparse that what we actually see is the colour of the hair fibre itself, keratin, which is a pale yellow, off-white shade. Granules filled with pheomelanin create Ginger hair. The pheomelanin in ginger hair is less densely packed in its granules. Its shape is somewhat more irregular than its black counterpart, eumelanin. It is slightly rounder and more spread out. From my results I found out that brown hair needed the greatest amount of force to break. Blonde hair needed the least amount of force to break. Black hair was second strongest and ginger hair was third strongest. The order of strength (from my results) of hair is as follows: Brown, Black, Ginger, and then Blonde. Brown hair stretched the most before breaking. Blonde hair stretched the least before breaking. Black hair stretched the second furthest and ginger hair stretched the third furthest. The order of length of hair stretched (from my results) before breaking is as follows: Brown, Black, Ginger, and then Blonde. Brown hair experienced the highest strain before breaking and blonde hair experienced the lowest strain before breaking. The order of strain experienced by hair (from my results) before breaking is as follows: Brown, Black, Ginger, and then Blonde. Brown hair experienced the highest tensile stress value before breaking and blonde experienced the lowest tensile stress value before breaking. The order of tensile stress experienced by hair (from my results) before breaking is as follows: Brown, Ginger, Black, and then Blonde. Graph 1 shows the average force required to break the four colours of hair. From this graph I can see that brown hair required the greatest force to break. Black hair also required a large amount of force to break and so did ginger hair. Black hair only required a small amount of more force to break then ginger hair. The breaking force required for brown, black and ginger hair was quite similar. Blonde hair required much less force to break compared to the other colours of hair. This proves that the disulphide bonds in the blonde hair are not a big advantage for strength of the hair. The darker the hair the stronger the force required for the bonds in the hair to break. The darker the hair the more resistant it is to breaking when forces are applied. The darker the hair the higher concentrations of melanin present along the hair cortex. The same sort of pattern is seen in graphs 2, 3, 4 and 5. Graphs 2, 3, 4 and 5 show the extension of hair when masses are added. Blonde hair breaks the earliest and brown hair breaks the latest. Graph 2 shows brown hair. Brown hair requires about 120g to extend up to about 70mm before breaking. The graph follows a basic trend and there are no anomalous results. All results fit the line of best fit. Graph 3 shows blonde hair. Blonde hair requires about 80g to extend up to about 35mm before breaking. The graph follows the basic trend and most results fit the line of best fit. There is one anomaly, though. The extension should not increase and then decrease. It should keep on decreasing. There must have been an error in recording this result. The results in graphs 2, 3, 4 and 5 are all averages. To work out the blonde values in table 32, the results in tables 12, 13, 14, 15, 16 and 17 were used. There was only one value for the extension at 80g, in table 15. This value was smaller than the average of all the extensions in all six tables. This sample of hair should have broken at 80g not 90g. This did not happen. This may have been an error in not measuring correctly. Graph 4 shows ginger hair. Ginger hair requires about 100g to extend up to about 60mm before breaking. The graph follows the basic trend until it gets to 55g point. From this point onwards the hair length increases and decreases dramatically. This should not happen. The reason why this happens is described above with the blonde hair. It is an error in measuring. Graph 5 shows black hair. Black hair requires about 140g to extend up to about 65mm before breaking. This graph is perfect. There are no anomalies. All points meet the line of best fit accurately. Graph 6 shows the average stresses and strains experienced by each hair colour. All four hair colours are plotted on the same graph so they can be easily compared against each other. Brown, blonde and ginger hairs do not follow the normal trend. The stresses and strains for these three should continue to increase. Tables 57, 58, 59 and 60 show where the stress and strain values came form. The results are like this because when the stress and strain values were calculated the average extensions were used, which had a few faults, as describe above. Graphs 7, 8, 9 and 10 show clearly what is happening to the stress-strain curves. Graph 7 shows one anomalous result. It has a high stress and strain value. Graph 8 also shows only one anomalous result. These two graphs show the basic trend. Graph 9 shows the normal trend until the stress value gets to 150Nm-2. Then it decreases and goes back on itself. This should not happen. The reason for this is explained above. There is an error in the extension averages. Graph 10 shows no anomalies. Graphs 11, 12, 13 and 14 show modified values for stress and strain in all colours of hair. Graph 11 shows the modified stresses and strains for brown hair. This graph does not bend backwards and the stress and strain values do not decrease. Graph 12 shows the modified stresses and strains for blonde hair. This graph does not show values of stress and strain decreasing. Graph 13 shows the modified stresses and strains for ginger hair. This graph has changed a lot. It reads much clearer. Stress and strain increases throughout. This is exactly what the graph should look like. Graph 14 is the same as graph 10. It did not need any modifications. The toughness of a hair is measured of its resistance to break. A lot of energy is required to break a tough material. Finally, the strength of a material (or tensile strength) is the greatest tensile stress it can undergo before breaking. Hair is an elastic material; it can stretch to a certain maximum point (elastic point) before breaking. The largest tensile stress that can be applied to a material before it breaks is known as its ultimate tensile stress (UTS). This value is sometimes referred to as the materials breaking stress. Graph 7 shows the stress-strain points for brown hair. Graph 11 shows a modified version of this. The UTS for brown hair is 359. 03. Graph 8 shows stress-strain points for blonde hair. Graph 12 shows a modified version of this. The UTS for blonde hair is 125. 48. Graph 9 shows the stress-strain for ginger hair. Graph 13 shows a modified version of this. The UTS for ginger hair is 286. 58. Graph 10 shows the stress-strain points for black hair. Graph 14 shows a modified version of this. The UTS for black hair is 158. 31. Overall I can see that brown hair was the strongest. This was not expected. I expected black hair to have the highest tensile strength, as it had a higher density of melanin along the cortex. Blonde hair turned out to be the one with the lowest tensile stress. Ginger haired people have a high density of the pheomelanin pigments in their hair fibre. Those who produce virtually no eumelanin have a red to orange colour depending on the density of the pigment in the hair fibre. Red haired people who have a greater relative proportion of eumelanin production have a deeper red to red brown colour. Ginger hair also should have a high tensile strength. This is what I saw in my results. Black hair should also have a high tensile strength. My results showed black hair to have high tensile strength but not the highest. There are other ways in which hair tensile strength could have been measured. Hair products like shampoos have an effect on hair tensile strength. They are now designed to change hair strengths. Different makes of hair shampoos could be used. Strength could be measured in a similar way to how I measured it. A control will be also be needed, with hair with no products added. These modifications in Graphs 11, 12, 13 and 14 show what the stress strain graphs should look like. In Graphs 7, 8, 9 and 10 the lines should not bend backwards. Statistical Test I will be using the (Chi squared test) X2. The formula for the Chi squared test is as follows: X2 = ? [(O E) 2 /E] O = Observed value E = Expected value The ((O E) 2) part of the formula considers the size of the difference between the observed and expected values. This difference could be either positive or negative. To avoid the mathematical problems associated with negative values, the difference is squared. The (E) part of the formula relates the size of the difference to the magnitude of the numbers involved. The sigma (? ) sum symbol is required because there is not just one pair of observed and expected values, but several (in this case four). By taking all the observed values of stress from tables 57, 58, 59 and 60, I can work out the expected value for each hair colour. I can then place these values in a table and work out the value for X2, using the chi squared formula. To calculate the degrees of freedom to be used can be found as follows: Number of categories minus 1. In this case: 4 1 = 3 The critical value (taken from critical values for the Chi squared test) at 3 degrees of freedom is 7. 81 (at the 5% level). The test statistic (X2 = 94. 235) is greater than the critical value(C. V = 7. 81, at the 5% significance level). We therefore can reject the null hypothesis and state there is a significant difference between the observed a Investigating the factors affecting tensile strength of human hair Evaluating: (Skill D) Limitations The selotape holding hairs in the paperclip at the top and at the bottom could have interfered with the tertiary structure of the protein, keratin. This could have increased or decreased the bond attractions in the hair to cause the hair to have a high or low tensile stress. This would make my results unreliable. The hairs showing higher tensile stress may just be showing how sticky the selotape is and how strongly it is holding the hair structure together. This though, would affect all my results, as all hair samples had selotape on them to hold them together at the top and at the bottom. So, this limitation would affect all hairs making it a very weak limitation. My conclusion will not be affected as this limitation affects all hairs.   The time in between weights were added is another limitation. When each weight was added the hair stretched. But when there were a lot of weights on hair, the hair stretched quickly and then the length was measured. After I finished measuring the hair had slowly stretched a little bit more. So the measurement was wrong. When the next weight was added extra extension was added onto the new extension. My results were affected by this because some extensions were false making some data imprecise. Therefore, my conclusion will be invalid, because some hair samples could have broken at lower weights if I had waited for the hair to stretch, very slowly until it broke. There needed to be a time limit in which I had to record the extension of the hair, before adding the next weight to the hair. The eye piece graticule can be a limiting factor. Different people measured hair thickness and recorded it to what they felt the thickness ought to be according to the scale. It was not very clear to see how thick the hair was, as the hair was faded under the microscope at all magnifications and the outline was difficult to see. This could affect my results as the thickness of hairs was used to calculate the cross sectional area of the hairs, which was then used to calculate the tensile stress experienced by the hair. This could make my tensile stress values incorrect. My conclusion therefore could be affected; by making out that a certain coloured hair had a higher tensile stress than another coloured hair, when really it shouldnt have. This would make my conclusion unreliable.   There were different shades of hair colour, for example, there were light brown hair colours and dark brown hair colours. It was sometimes hard to distinguish between brown and blonde. This was the same for blonde hair. This would have an affect on the reliability and precision of my results making the accuracy of the strengths of different colours of colours of hair inaccurate. There should have been a certain shade of colour of hair (same amount of melanin in each brown hair) used for each colour sample. My conclusion will be imprecise because brown or blonde hair shades could cause incorrect results and make my conclusion incorrect.   The 10g mass is a limitation as the hair could break at lower masses than they actually did, for example a hair that broke at 50g could have broken at 41g, but I wouldnt know that as I only used 10g masses. So, I got false readings implying the hair is stronger than it actually is. If smaller masses were used my results would be much more accurate to make my conclusion reliable. This limitation could cause my conclusion to be invalid, causing the hairs strength and point on breaking higher or lower than it actually is. Conclusion After doing my statistical test I can reject my null hypothesis and accept my hypothesis and say that brown, blonde, ginger and black hairs differ in tensile strength. I have proved this difference in my calculations, mainly in graphs 1 and 6. From my results I can see that darker coloured has a higher tensile stress compared to lighter coloured hairs. In my hypothesis I said that lighter coloured hair would have a higher tensile strength than darker coloured hair, due to lighter coloured hair having sulphur-sulphide bonds, which are very strong. I have disproved this. Through testing all four colours of hair I can see that these strong sulphur bonds do not reflect any tensile strength qualities. Lighter coloured hair does not have an advantage over dark coloured hair when it comes to tensile strength. It mainly depends on the type of melanin the hair contains. The denser the melanin quantity is the stronger the hair.