Evolution of the laboratory centrifuge Essay Example

Evolution of the laboratory centrifuge Essay Introduction The research lab extractor is one of the most of import instruments available today for sample readying. It is widely used and considered to be the most efficient manner to separate constituents of a sample with different densenesss. Many types of extractor are available today, runing in size from bench top extractors, with a capacity of 1.2 L and a maximal burden of 1.5 kilograms, to big free standing extractors with a capacity of 5 L and a maximal burden of 6 kilograms, or even larger. Some of the larger machines are able to make velocities of up to 10,000 revolutions per minutes, while the smaller extractors tend to hold maximal rotational velocities below 300 revolutions per minute. We will write a custom essay sample on Evolution of the laboratory centrifuge specifically for you for only $16.38 $13.9/page Order now We will write a custom essay sample on Evolution of the laboratory centrifuge specifically for you FOR ONLY $16.38 $13.9/page Hire Writer We will write a custom essay sample on Evolution of the laboratory centrifuge specifically for you FOR ONLY $16.38 $13.9/page Hire Writer Bench top extractors, capable of velocities of about 3000 revolutions per minute, have been in usage since the mid-1800s. Early extractor instruments were manus powered, with electric extractors foremost used after 1912. The early extractors tended to be used for non biological applications, such as separation of milk and aggregation of precipitates. Evolutionary timeline Use of the procedure of centrifugation can be traced back to the mid fifteenth century, when hand-driven extractor systems were used for the separation of milk. In 1864, this ad hoc system of milk separation was foremost commercialized by Antonin Prandtl who developed the first dairy extractor with the intent of dividing pick from milk. The potency of the extractor in the research lab scene was foremost exploited by Friedrich Miescher. In 1869, Miescher foremost used a petroleum system of extractor to insulate a cell organelle. This procedure led to the find of an of import new category of biological components, subsequently to be known as nucleic acids. The work of Miescher was rapidly recognized and developed by others. In 1879, the first uninterrupted centrifugal centrifuge was demonstrated by Gustaf de Laval. The development made the commercialisation of the extractor a practical possibility for the first clip. The following major measure frontward in the development of the extractor came during the 1920s and 1930, when the ultracentrifuge , capable of accomplishing 900,000 g, was developed by the Swedish colloid chemist, Theodor Svedberg. As the theoretical accounts capable of making 900,000 g tended to hold little rotors, ultracentrifuges with larger rotors which could run at around 260,000 g were more normally used in everyday work. Svedberg used his extractor to find the molecular weight and fractional monetary unit construction of extremely complex proteins such as haemoglobin. This information started a revolution in our apprehension of the constructions of proteins. In 1926 Svedberg received a Nobel Prize for the innovation of the ultracentrifuge and for his work in colloid chemical science. Svedberg s ultracentrifuge, nevertheless, was basically an analytical instrument, specifically designed for the accurate recording of deposit boundaries. It would hold been impossible to change over it for usage in preparatory procedures, nevertheless, for the simple ground that its rotor axis was horizontal. The passage from analytical instruments of this type to the modern preparatory ultracentrifuges came through the attempts of the Gallic physicist, Emile Henriot, who was able to accomplish really high rotational velocities by agencies of a bearing-less top, driven and supported by tight air. Interest in the isolation of viruses brought Edward Pickels and Johannes Bauer together to construct the first high velocity vacuity extractor suitable for the survey of filterable viruses. Subsequently, Pickels went on to develop the much more convenient electrically driven ultracentrifuge. During the early 1930s Martin Behrens developed improved centrifugation techniques utilizing denseness gradients of nonaqueous dissolvers for the separation of karyon. His attack in tissue fractional process aimed to insulate one or more identifiable constituents from disrupted cells that could be physically and chemically characterized. In 1946, Pickels cofounded Spinco ( Specialized Instruments Corp. ) in Belmont, California and marketed an ultracentrifuge based on his design. However, gross revenues of the engineering remained low, and Spinco about went insolvents. In 1942 Albert Claude and James Potter published a landmark paper, Isolation of Chromatin Threads from the Resting Nucleus of Leukemic Cells . This paper outlined a series of centrifugation stairss in which either the supernate or the deposit was collected until chromatin togss were retrieved from the concluding deposit. In 1949, Spinco introduced the Model L, the first preparatory ultracentrifuge to make a maximal velocity of 40,000 revolutions per minute. This marked a dramatic alteration in the lucks of Spinco. In 1954, Beckman Instruments ( now Beckman Coulter ) purchased the Spinco company, organizing the footing of its Spinco extractor division. Beckman instantly set about presenting betterments in the design of extractors many of which are still used today. For illustration, the thrust systems were replaced with high velocity motors, and the stuff used for the rotor blade was updated. In 1962 Netheler A ; Hinz Medizintechnik, a company based in Hamburg, and known today as Eppendorf , developed the first microcentrifuge for laboratory use. This microliter system ( model 3200 ) was introduced for usage in everyday analysis labs on a microliter graduated table, and offered merely one dial to command centrifuge clip. The Microliter System was the footing for a wide scope of tools for the molecular research lab, which were later developed by all different sorts of biotech and labware companies. During the 1980s, Beckman launched floor ultracentrifuges. During the 1990s, Beckman launched the Avanti A ; reg ; high public presentation extractor. In 2007, Helmer launched two new extractor bundles for the clinical research lab, the HighSpinTM and CentraSpinTM Plus. The HighSpin bundle was a compact extractor for high volume sample processing, offering a entire spin capacity of 78 tubings, while the CentraSpin Plus bundle was designed for low volume sample treating needing added velocity and capacity. It offered a entire spin capacity of 28 tubings at up to 5000 RPM. Future of extractors Centrifugation has come a long manner since the procedure was foremost commercialized for research lab usage in the fortiess. The original rotors, such as those built by Svedberg, were made of tensile steel. Today stuffs such as aluminium metals and Ti are used in order to defy high centrifugal forces. Standard features now include procedures for chilling, scheduling, automatic instability sensing, noise decrease, or mutable rotor systems. Vacuum systems have besides been added to centrifugate instruments to cut down clash and keep temperature control. The development of other tools, such as negatron microscopes, has allowed research workers to better examine and look into the atoms being centrifuged. With research into proteins and cell nucleic matter deriving going more and more of import and gaining gait all the clip, the extractor will go on to be a critical piece of laboratory equipment for the foreseeable hereafter.

abortion-a womans choice essays

abortion-a womans choice essays Abortion is a very controversial subject. There are many beliefs and exceptions. Many people fail to realize or understand that it is a personal decision. The decision to or not to abort may be more complicated than people might realize. Regardless of the fact of morals, a woman has the right to privacy and her choice to abort. Only the woman has the control over her body and reproductive system. I believe abortion is a womans choice because I feel that a woman has the right to decide what is right or wrong for her, her body, and her life. To some people, abortion is wrong no matter how they look at it. But, in some cases, they havent had personal experiences with abortion. When theyve had to walk in the same shoes, they sometimes change their opinion rather quickly. When a person has a friend or relative who unexpectedly gets pregnant, they are more likely to understand why abortion, in some cases, is maybe the only thing to do. I used to be against it until my cousin, Jennie, had an abortion. She was only eighteen years old with one child and was going through a difficult divorce. Her husband often beat her and told her if she ever left, hed kill her. She finally did leave, but she also found out that she was pregnant. She knew she was in no shape to raise another child and realized that she didnt need anything else to tie her to her husband. I understood her reasons, and I agreed that it was for the best. Also, in cases of rape, sometimes the women have found out that they are pregnant; abortion is probably the first thing that comes to mind. Especially, in this case, I believe the woman has the right to her choice of an abortion. I would think that having to go through the emotional pain of being a victim of rape would be punishing enough without having to raise the child of a rapist. There could be some resentment towards the ...

Summary of health article Essay Example | Topics and Well Written Essays - 500 words

Summary of health article - Essay Example The database, managed by United Health Group Inc. subsidiary Ingenix Inc., has been alleged to be seriously flawed and manipulated by the insurers, resulting to poor reimbursements and higher medical bills for consumers. Most recent complaints on this accuse Aetna of manipulating the database to get rid of valid high charges. According to a complaint filed recently in U.S. District Court for the District of New Jersey, Aetna and Ingenix collaborated to fabricate figures favorable to the company, thus corrupting the database to yield inaccurate results, lowering down the reimbursements for doctors. The complaint further claims that this has greatly damaged physician-patient relationships. Dr. Nancy H. Nielsen, President of A.M.A., stated that the association is putting an end to the health insurers’ unfairly manipulative business practices, disregarding patients and the legally acceptable costs of caring for them, citing a certain case of an anonymous surgeon who was paid way below his billed charges. To these, Aetna spokeswoman Cynthia Michener commented that they will by all means defend the company amidst similar claims by consumers in New Jersey and Connecticut. She further expressed disappointment over the medical community’s move to sue them when the company has succeeded to develop better collaboration with doctors. Cigna, on the other hand, believes that physician’s pricing must be more transparent in order to achieve lower costs at higher quality

Human Development Essay Example | Topics and Well Written Essays - 1250 words - 2

Human Development - Essay Example Pavlov’s research indicated that behaviors could be learned via conditioned associations. The learning process was argued to have grounds on which environmental stimulus and naturally occurring stimulus could be associated (Watson 6). Therefore, this means that the focus of behaviorism is purely on the idea that human behavior is acquired as a result of interaction with the environment (Berger 2005). In regard to contribution of behaviorism to my development, it is apparent that behaviorism played a key part in dictating my current personality. Having been brought up in rural areas, most of the behaviors of the rural people were vested on me because I always interacted with them. The rural school setting is different from urban school setting. We used to travel for long distances to school and believed that schooling is a difficult task that one has to strive to achieve. Nevertheless, this was instrumental to me because I have always worked hard to achieve my desires. This is contrary to urban people who are brought up in urban settings. They have little struggles because the life in the urban is a bit comfortable than the life in the rural settings. This is equally the same case to children brought up in wealthy families and those that are brought up in rural settings. The personality of these two groups of people is wide owing to the lifestyle that they are exposed to. It is argued that people brought up in areas where crime is prevalent tend to adapt to criminal behaviors. Most people who engage in crime are either due to the influence of drugs or as a result of poverty. Since such people have little they can do to change their lives, they resort to crime and drugs as a way of either reducing stress or use crime as a way of earning a living. Hence, it is true to stipulate that the environment that such people find themselves in influences their character so that they can fit in it. Theory of cognitive development was pioneered by Jean Piaget who

Conduct research on ship broking Essay Example | Topics and Well Written Essays - 1500 words

Conduct research on ship broking - Essay Example Ship broking happens through the shipbrokers who act as the mediators or the agents of the vessel owners and the clients (Schramm 2012, p.146). A competitive ship broking is an opportunity-based business where the brokers may swift and smart moves to accomplish their deals. The brokers have diverse understanding of latest market progress within their areas of operations and because of these skills they possess, they are highly valued by charters. There are different types of groups in ship broking depending on the kind of cargo involved. The persons who negotiate and organize the charter of a vessel on behalf the charterer and ship owner are the brokers who specialize in dry cargoes brokering, wet cargoes or tanker brokering (Lange 2011, p.41). The fundamental operation of the shipbrokers is to represent the ship-owner and find the jobs for the ships according to the principals of the vessel owner. In case the shipbrokers represent a cargo interest, the brokers’ role is to find suitable ships for the cargo in accordance with the charterer principals. The broker must have a vast knowledge of vessels and cargoes, information about ports, methods of loading and release of various cargoes, weather patterns, demand, and supply of ships. With the advancement in communications technology and sophisticated computing techniques shipbrokers, networks have intensified the brokering business (Talley 2012, p. 305). With the modern digital communication evolution communication with brokers have become accessible from any part of the globe be it on land, sea, or air. The exchange of information has emerged reliable and affordable. The large amount of data traverses across the world very fast including the details of fixtures because of advanced communication technology (Carter 2014, p.188). The concluded information about profits, and the market reports, government policies, economic

The Influence of Police Culture

The Influence of Police Culture In order to appropriately address the topic of discussion, firstly, it is important to understand what is meant by the concept police culture. After establishing its definition, it then becomes a task to assess whether police culture does indeed have a negative influence on the way the police work as an institution or whether it merely ensures that a certain level of consistency in achieved in terms of the way officers conduct themselves in their daily working environment. The term police culture has in itself been a topic of some discussion with sociologists being divided over what the definition should and should not include as there isnt an established, concrete definition of the concept. For example one contributor who has attempted to rectify this problem is Reiner (1992) who describes it as the values, norms, perspectives and craft rules which inform police conduct (Reiner 1992 quoted in Loftus 2009: 3). Whereas another definition comes from Manning (1989) who defines it as accepted practices, rules, and principles of conduct that are situationally applied, and generalised rationales and beliefs (Manning 1989 quoted in Loftus 2009: 3). Although these definitions dont appear too different at first glance, there is in fact a clear distinction between the two that should and must be made mainly the fact that Manning stresses that such principles of conduct are situationally applied, which of course suggests that police culture is not always necessa rily influential to an officers conduct. Some officers can and do hold a certain level of professionalism when taking to the streets and any values which may corrupt such professionalism remains behind closed doors in the company of their colleagues only. Yet Reiners provided definition suggests that the police culture remains with the police officer when they take to the streets and he/she then enforces the informal rules which have been established with their fellow colleagues, which generalises that all police officers act in accordance to the police culture . However what must be taken from both definitions is that there is reason to suggest that there is a network of a shared set of norms and values within police forces which could potentially have an effect on how they operate in a working environment. What also must be stressed is that there is also a distinction between the terms police culture or cop culture (as its otherwise known) and canteen culture which is another concept which crops up time and time again in countless criminology texts. Canteen culture, as mentioned by Waddington (1999), is understood to be the norms and values held by police officers whilst off-duty, whereas police culture is the norms and values which are expressed during the course of their occupational lives (Waddington 1999 cited by Crank 2004: 16-17) Newburn (2007) also makes this a key point by explaining that there is a common tendency to assume that what police choose to say and how they choose to act when off-duty is not only indicative of how police officers think, but also how they act in public. (Newburn 2007: 216) Yet Waddington has a problem with such assumptions, as he claims that this is not the case all of the time. The way officers act and the views they hold whilst off-duty, whether in the pub with friends or work colleagues is but a safety valve to release the pressures of the realities of life as a police officer (Waddington quoted by Newburn 2007: 618) Such an argument claims that in experiencing somewhat controversial views outside of the working sphere, a person is opened up to new perspectives which sociologists such as Waddington would argue helps to avoid them from being over-exposed to a particular ideology which could then influence the way in which they carry out their duties. But what also must be considered is just how valid Waddingtons argument actually is. Yes, of course in some instances exposure to different attitudes and values can be beneficial to an officer in terms of becoming more aware of the possibility of potential new threats, but there are also some officers who would then, due to any extreme views which they may have been subjected to, may target an individual or a group of people because of the stereotypes attached to such persons and not because of genuine suspicion. Police culture, it is claimed by Reiner (1992) has many characteristics in which it can be identified with, with suspicion being just one of them. Suspicion is an absolute necessity in the police force as it is suspicion that helps the police prevent crimes from occurring and therefore everyday working experiences encourage officers to generalise people into particular labels, whether or not this is a legitimate way to suspect possible offenders (Reiner cited by Newburn 2007: 618). Unfortunately there is a strong link between suspicion and ethnicity, with ethnic minorities suspected to engage in criminal activity more than people of white ethnic origin. The 2005/2006 Home Office statistics relating to police searches provide a great example for this. In interpreting the results of stop and search practices, 15.4% of the entire UK Black community were stopped under the Police and Criminal Evidence Act 1984 (PACE Code A) in comparison to only 1.6% of the entire white population. This d iscrimination however doesnt just end with the police; it branches out into other areas of the criminal justice system such as the prison service. Genders Player in (1989) claimed that prison officers sometimes use active stereotypes and labels to help order their working environments by predicting inmate behaviour in order to maintain authority at all times. Prisoners within the ethnic minority demographic were perceived as having a chip on their shoulder, as they felt they were being victims of racial persecution and thus the officers paid more attention to monitoring their behaviour. Arguably the most problematic characteristic of a police culture in terms of the impact it has on police and community relations is the element of racial prejudice. One of the most notable examples of racial prejudices derives within the Macpherson Report (1999), arguably the most notable report in criminology, which followed the death of black teenager Stephen Lawrence. The report found that the police were institutionally racist after discovering that police were ignoring crucial evidence to the investigation and were displaying discrimination in the interviewing process of suspects suggesting that it was black on black crime, despite Lawrences friend (an eye witness) being adamant that it was a racially motivated murder. Despite the findings of the report and the provisions set out to try and avoid the recurrence of racial controversy within the police, there is evidence to claim minority ethnic recruitment still remains low and there are still continuing problems in terms of pol ice relations with ethnic minorities (Croall 2011: 221-222). The aftermath of the Macphereson Report proved that institutional racism was still rife in police recruitment centres, as four years onwards a BBC documentary titled Secret Policeman was aired which centred on the police recruitment centre, Bruche which was located just outside of Warrington. Consequently after the footage of the documentary went public, the centre was forced to close so as to not further damage the reputation of the police. New police training systems were also introduced nationwide to try and expel racism from the police force as a result of the documentary. (The Observer 2004) How officers are socialised is of another great significance. The next characteristic of a police culture is the degree of solidarity, and it is this element which although is reinforced in numerous police forces, it is an aspect which is initially developed between candidates during the recruitment stages. Due to the intense nature of the job including the long hours which officers are required to work, the intensity of some of the work and the expectation of being the ones to prevent social decline, officers are encouraged to bond strongly and they learn to rely on one another, and as such tend to develop an us-against-them attitude. This resulting mentality, in some situations, leads to not officers making pacts with one another in which they agree not to grass on fellow officers for any discrepancies that they might have witnessed whilst on duty. This is more commonly known as The Blue Code of Silence. Just like any other subculture, in order to ensure cooperation and commitment to the Blue Code, a tribal value system is implemented which makes police culture sort of like a family structure in which members of the system will receive emotional support and security from the other officers upon requirement. Several police departments worldwide have been found to have followed the Blue Code, probably most notably was a New York police department which the Mollen Commission reported were to be covering up infringements of their officers. In such case where an officer was to break the Code, then his/her reputation and essentially his career too would be ruined as he/she would then be ostracised and labelled a whistleblower and thus it is the threat of this tarnished reputation that encourages the officer to obey the unwritten rules. (Loftus 2009: 14) Accusations of excessive force by members of the police force are far from uncommon, particularly in America. And it is the use of excessive for which Manning (1970) claims is a perfect example of police culture and how it can have a negative influence on the way officers carry out their duties. (Manning 1970 cited by Crank 2004: 107) However, excessive force is not detected in all cases. Victims of police brutality may feel that the odds are stacked against them in filing a complaint to an officers superiors and are thus reluctant to do so and may feel that even if a complaint is acknowledged and results in a court case, the judge and jury would overlook excessive force as the perceived perspective would be that the victim shouldnt have gotten his/herself in a position in which the use of force was needed in the first place and thus the consequences of their anti-social behaviour was deserved. Yet with that said, there are of course examples where the victim of police brutality are non-deserving of such treatment and thus the police force as a whole have come under criticism despite it being a minority of officers that participate in such excessive violence. For example a British police constable, PC Simon Harwood, was charged with the manslaughter of Ian Tomlinson during the G20 protests in 2009. Tomlinson was finding another route home after his usual route was blocked by the protests when he was struck by PC Harwood with a baton and then pushed to the ground Tomlinson fatally collapsed and an autopsy revealed the cause of death was a heart attack, which the actions of PC Harwood where no doubt a triggering factor. PC Harwood was acquitted of manslaughter, which only strengthens the argument mentioned previously that the courts are sympathetic to the police when the question of reasonable/excessive force is raised. However, it must be stressed that many police forces do have provisions in place to deal with any complaints of unacceptable behaviour regarding their employees in which inquiries will be carried out and, if found guilty, the officer in question may be reprimanded, suspended or permanently dismissed depending on the circumstances. Also, as in the case of PC Harwood they may also, if necessary, face criminal prosecution or at the very least face a civil hearing if the victim wishes to sue for damages caused by the officers ill-considered actions. But how are the police able to get away with these kinds of infringements? Again, it all relates back The Blue Code of Silence. As already mentioned earlier in the essay, officers of some police forces claim ignorance of any wrongdoings of their work partners and in some cases, they testily which is typically an American slang term for when an officer gives false testimony in court. Relating back to the tribal values, not participating in activities such as testilying would lead to an officer being shunned and sometimes even harassed to the point of retirement as they arent assisting their family members, in effect betraying their own kind. In 1994, the Mollen Commission found that some officers within the NYPD fabricated crucial documents such as arrest reports and warrants and some officers were found to have falsified witness statements for the purposes of manipulating the jury as they felt that an accused individual deserved it. This is particularly common in cases of bad character in which an accused has had a history of offences but has escaped punishment. Although corrupt as it is, testilying is merely seen as another way of getting the job done.   In conclusion, there is a huge interest towards police culture due to the impact it can and sometimes does have on society. if it is to have an influence on the way the police go about their work. The police hold a massively important role to society as they are a visible symbol of law and order and are granted various powers such as those which enable them to arrest members of the public who they feel prove a threat to the rest of society. Although most officers do operate in a reasonable manner, it is generally the actions of the minority which enable the public to misconceive that all officers are bigoted and aggressive. Such generalisations lead to a mass distrust of the police and tensions then begin to occur between the police and their publics. You only need to look at the summer riots of 2011 (which were reported to have been sparked by an officers seemingly unauthorised use of deadly force on a suspect) to see just how damaging poor police-community relations can be to the p olices image as a social institution.

The Typical Detective Genre Portrayed in Sherlock Holmes Literature Es

The Typical Detective Genre Portrayed in Sherlock Holmes' Literature The late Sir Arthur Conan Doyle was a phenomenally successful writer, not only in the Victorian era but is still popular today; his Sherlock Homes stories were perhaps his most successful, in which he combines realistic situations of murders and scandals with the improbable situation of such a successful detective. Victorian London was an exceptionally dangerous place to live. Prostitution, opium dens and murders were inescapable. A women's role within the household was very much dependent on her class and her husband, purely due to the fact was that herr husband was the breadwinner. They were to stay at home; sex was supposedly purely for reproduction. London's police force was around but famously was rather ineffective with solving crimes. This is one of the reasons Holmes was extremely popular; almost a fantasy world where a character with such an inquisitive mind could solve the most challenging misdemeanours. Conan Doyle sets his stories in the heart of England, London. Perhaps this is because the busy bustling town is ideal for such a character, London Is the most important place in England, and therefore surely Holmes must be the most important detective? Conan's Doyle's stories are all in some way alike; they all have a villain, or somebody who is believed to break society's rules. This helps the audience to gain interest in how the villain will survive with Holmes on their case, how they will be punished in the context of the story. Neville St Claire in 'The man with the twisted lip' was found guilty of dressing as a tramp, to deceive people to give him money. Maybe he did this for greed; he obviously was not in favour of ga... ...chievous scheme; "I surprised you by beating upon the pavement with my stick. I was ascertaining whether the cellar stretched out in front or behind." No reader would have predicted this was the reason for the beating of this stick. This is the type of fascinating unpredictable actions, which make detective stories almost addictive until the end and appealing to the reader. Conan Doyle made sure that all questions during the story are answered and no queries left hanging. This is alluring to all readers as the endings are moral and all dilemmas are resolved. Detective story's have become one of the most popular genre, authors such as Sir Arthur Conan Doyle manage to make even the most straightforward storylines interesting and appealing to all readers simply because of false trails, red herrings and the way information is with held to the reader.