Acute Human Immunodeficiency Virus ( Hiv ) Infection

Acute Human Immunodeficiency Virus (HIV) infection is the small period of time after a person has been exposed to HIV and before they have seroconverted. Seroconversion is the process in which the body starts to create antibodies to fight the HIV virus (Pietrangelo, 2013). During this period of time, which is usually a few days, the virus replicates rapidly. The rapid replication results in extremely high amounts of HIV in the blood because the body has not had time to respond to the infection. As the viral load increases more CD4 white cells are destroyed. CD4 cells are a responsible in protecting the body from infection. When these cells are destroyed they no longer are able to adequately activate the body s immune system. (AIDS.GOV).†¦show more content†¦Signs/symptoms of Acute HIV Infection Including HP Not all patients with HIV will have signs or symptoms during the acute infection phase. If a patient is having symptoms they can often times think that they have the flu. Acute HIV infection symptoms can show up 2-4 weeks after exposure and last from a few days to several weeks (Cherney, 2014). If they are exhibiting symptoms they may present as having a fever, swollen lymph nodes, skin rashes, myalgia, diarrhea, oral ulcers or thrush, and fatigue. Lab results may also show leukopenia, thrombocytopenia, or an elevation in transaminase (DHHS, 2015). Differential diagnoses include the flu or Epstein- Barr Virus since these also present with similar symptoms. A thorough health history must be taken with patients before an exam in order to identify risk behavior. Important things to ask about are sexual history, partners and possible exposures, any drug use (especially intravenously), and any current STI’s (HRSA, 2014). Upon physical exam things to look for or may see with an acute HIV infection would be ecchymosis, purpura, petechiae, Kaposi sarcoma, lymphadenopathy, oral candidiasis, or hepatosplenomegaly (Aberg et al., 2014). Cultural Implications The numbers of new HIV infections per year has remained relatively the same since the 1990’s (CDC, 2015). Out of

Essay on King Hammurabi’s Efforts to Unify Mesopotamia

During this era, ancient Mesopotamia was under the rule of theocratic monarchies. It was believed that the sole ruler was governing specifically for the gods and catering to their wishes. Mesopotamians were polytheistic, or worshippers of multiple gods, and extremely devout in their faith. They believed that the gods determined all situations and occurrences. As a ruler, King Hammurabi found Mesopotamia to be tremendously divided. At the time of his rule, Mesopotamia was dissected into separate city-states that were often feuding. The creation of King Hammurabi’s code of laws was a means to provide unification for all of the people of Mesopotamia. It was King Hammurabi’s hope that a central system of laws would bind the separate†¦show more content†¦This can be seen with law 200, which stipulates that if one is to knock out the teeth of someone in equal social class status, the same will be done to him. This law also demonstrates the immense importance that was placed on social class. The judiciary system deemed punishments based on the offender and victim’s social classes. This can be seen with laws 197, 198, and 199. Although the crime is the same in all these three laws, breaking someone’s bones or damaging his eyes, the punishment is drastically reduced with decreasing social class of the victim. The subject matter of the laws clearly signify the importance that ancient Mesopotamian society placed upon agriculture. Law 53 notes that if a man’s dam is faulty and breaks and then subsequently floods the surrounding fields, he is at fault. As punishment, the man’s dam will be sold to pay for the damage. Law 53 elaborates on this law, noting that if the man can not replace the damaged grain of the surrounding fields, his possessions will be equally divided between those whose crops have been damaged in the wake of his error. These laws are quite strict in their punishment, noting the vitality that agriculture was to an average Mesopotamian’s wellbeing and livelihood. King Hammurabi’s laws were also quite personal. The laws delvedShow MoreRelatedThe Birth of Civilization18947 Words   |  76 Pages1 The Birth of Civilization Mohenjo-Daro Figure. Scholars believe this limestone statue from about 2500 B.C.E. depicts a king or a priest from Mohenjo-Daro in the Indus valley in present-day Pakistan. Does this figure seem to emphasize the features of a particular person or the attributes of a particular role? Hear the Audio for Chapter 1 at www.myhistorylab.com CRAIMC01_xxxii-031hr2.qxp 2/17/11 3:22 PM Page xxxii EARLY HUMANS AND THEIR CULTURE page 1 WHY IS â€Å"culture† considered a defining

Transducers Used in the Cardiac Ultrasound Machine. free essay sample

Abstract Ultrasound imaging depends on the ability of piezoelectric crystals to generate sound when excited with alternating current and the reverse effect of charge accumulation or current flow when such crystals are subjected to pressure from sound waves. The first known ultrasound imaging machine was designed by K. T. Dussik in Australia in 1937. However, despite its widespread acceptance today, medical ultrasound did not develop as rapidly as X-ray imaging. Despite the relatively slow start, medical ultrasound imaging is very widely accepted today because there is no ionising radiation involved and hence the procedure is relatively safe. Ultrasound equipment is also cheaper as compared to X-ray imaging, magnetic resonance imaging, MRI and other techniques associated with nuclear medicine. The procedure involves minimal patient discomfort and is very useful for examining the soft tissues or the developing foetus. A dramatic increase in the number of older patients with chronic heart and valve disease has resulted in a prolific demand for the ultrasound cardiac imaging machines which can satisfy the requirements associated with fast and cost effective measurement of cardiac anatomy or function. We will write a custom essay sample on Transducers Used in the Cardiac Ultrasound Machine. or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page One of the critical elements in the medical ultrasound imaging system is the ultrasound transducer without which signal processing and visualisation of the soft tissue images is impossible. Although many naturally occurring substances such as quartz exhibit the piezoelectric effect, lead zirconate titanate (PZT) ceramic ferroelectric materials have for many years been used for biomedical applications because of their superior characteristics for soft tissue imaging. Polyvinylidene difluoride (PVDF), transducer material has demonstrated advantages as a high frequency receiver. Single or multilayer transducers made of these elements can be used for ultrasound imaging as single transducers operating in A-mode or a two or three dimensional transducer array for B-mode, C-mode or M-mode ultrasound imaging. This brief essay takes a look at transducers for medical ultrasound. Introduction The principle of operation of a cardiac ultrasound imaging device is based on the information that is provided by the varying delay times of echoes that are reflected from various depths of the human body tissue as a result of the ultrasound pulses that are generated by an ultrasound transducer being incident on the body tissue. Delay times of echoes from different depths are different and ultrasound is reflected from the interface of different types of tissues. A Doppler shift in frequency is also generated as a result of moving objects and the attenuation of ultrasound waves depends on the type of tissue that the ultrasound wave is travelling through. The ultrasound transducer which is responsible for the generation and detection of reflected ultrasound is, therefore, an essential component of the ultrasound imaging device. Ultrasound transducers work on the basis of the piezoelectric effect in which an alternating voltage applied to piezoelectric crystal material causes the crystals to become electrically polarised as a result of the applied electric field and hence vibrate with the alternating voltage to produce sound. Such crystals also become electrically polarised when stress is applied to them and hence any sound waves which are incident on them result in charge accumulation on the crystal surface and hence the generation of an alternating voltage. Thus, an ultrasound transducer consists of a suitable piezoelectric material sandwiched between electrodes that are used to provide a fluctuating electric field when the transducer is required to generate ultrasound. When the transducer is required to detect ultrasound, the electrodes may be used to detect any fluctuating voltages produced as a result of the polarisation of the crystals of the piezoelectric material in response to incident sound which generates fluctuating mechanical stresses on the material. Piezoelectric materials include quartz, ferroelectric crystals such as tourmaline and Rochelle salt as well as the group of materials known as the piezoelectric ceramics, which include lead titanate (PbTiO3) and lead zirconate (PbZrO3). These materials are also known as piezoelectric ceramics which are used in ultrasound transducers for biomedical applications. Polyvinylidene difluoride (PVDF) is another transducer material which has demonstrated advantages as a high frequency receiver. Piezoelectric ceramics are sold with the brand name PXE by Philips Company and are solid solutions of lead titanate (PbTiO3), and lead zirconate (PbZrO3) which have been modified by additives which are a group of piezoelectric ceramics known as PZT. PXE materials are hard, chemically inert and unaffected by a humid environment. The crystals in a ferroelectric material of which PXE is made up of align themselves randomly in a number of directions. With such a random orientation of crystals, the material will exhibit no piezoelectric effect. In order to have a piezoelectric material which is capable of being used for ultrasound transducers, the material has to be subjected to a strong electric field at high temperatures. This has the effect of permanently locking the crystals in the direction of the applied electric field and making the crystal piezoelectric in the direction of the electric field. Hence, a piezoelectric ceramic material may be converted into a piezoelectric material in any given direction by applying a strong electric field to the material in the given direction at an elevated temperature. This treatment, which is known as poling, is the final stage in the manufacture of a PXE piezoelectric. Metal electrodes perpendicular to the poling axis are deposited on the material so that an alternating electric field may be applied to generate ultrasound or ultrasound vibrations may be sensed by sensing the electric field across the piezoelectric material. The voltage across a piezoelectric ceramic PXE material is usually directly proportional to the applied stress. The construction of a simple, single element piezoelectric transducer is as shown below. The Construction of a Single Element Piezoelectric Transducer Ultrasound imaging in the A-mode directs a narrow beam of ultrasound into the tissue being scanned and the echo which may be displayed on a CRT screen provides a measure of the distance between reflecting surfaces in the body. In the B-scan mode, the echo signal is brightness modulated which makes it possible for information related to tissue depth to be displayed on the screen in a visually effective manner. An ultrasound transducer array operating in B-mode permits a picture of the tissues within a patient’s body to be displayed on a CRT device. M-mode ultrasound imaging presents tissue movement by scanning an A or B – line on a monitor as a function of time and movements in this line indicate movements in the tissues within the body. In C-mode ultrasound imaging a second transducer is used to detect echoes sent out by the first transducer, presenting a 2-D map of the ultrasound attenuation within tissues. Having discussed the principles of operation of a piezoelectric medical ultrasound transducer, it is now appropriate to consider the practical problems associated with the construction of such transducers. This is done below. The Design of Ultrasound Transducers A transducer which is constructed out of piezoelectric material will have a natural frequency of resonance and it is appropriate that the transducer should be excited with alternating electric field which matches the natural resonant frequency of oscillation of the material. The ultrasound frequencies that are used in medical imaging applications range from 1 MHz to 15 MHz and echocardiography is usually performed at frequencies of 2. 5 MHz. Hence, transducers which are used for ultrasound imaging have to be tuned for different frequencies. For a transducer material in which ultrasound waves travel at the speed c, with a resonant frequency f, the thickness of the material is related by the formula f=c/2d. Hence, it is possible to tune various transducers constructed of the same material to different frequencies by adjusting the thickness of the material. The ultrasound transducer can be excited by a continuous wave, a pulsed wave, or a single voltage pulse depending on the requirements for observing a continuous image, echo ranging or other tissue measurements. The rear face of the piezoelectric crystal material is usually supported by a backing material which is tungsten loaded araldite, so that the vibrations in the piezoelectric material are rapidly damped after the initial excitation. It is important to couple the piezoelectric transducer to the body of a patient so that the incident ultrasound energy can be effectively transmitted into the body tissue that is being scanned. In order to do this, matching layers of suitable acoustic material are used along with a gel which makes it possible for the ultrasound waves to penetrate the tissue more efficiently. As far as possible, the characteristic acoustic impedance of the tissue being scanned is matched with the acoustic impedance of the transducer. The characteristic acoustic impedance of the tissue is defined as: In the formula, c is the speed of ultrasound in human tissue which is about 1540 m/sec with a variation of +/- 6% and is the tissue density. K is the bulk elastic modulus of the tissue being scanned. The acoustic parameters of an ultrasound transducer include its nominal frequency, the peak frequency which is the highest frequency response measured from the frequency spectrum, the bandwidth of the transducer which is the difference between the highest and the lowest – 6 dB level in the frequency spectrum, the pulse width response time of the transducer, which is the time duration of the time domain envelope which is 20 dB above the rising and decaying cycles of a transducer response, the loop sensitivity for a medium on which a test is performed which is characterised by: Here, Vo is the excitation pulse voltage in volts, while Vx is the received signal voltage from the transducer. The signal to noise ratio for a biomedical ultrasound transducer is also an important parameter for an ultrasound transducer and this is defined as: In the above expression, Vx is the received signal voltage from the transducer in volts in response to a specified tone burst or pulse and Vn is the noise floor in volts. The signal to noise ratio for an ultrasound transducer is a measure of the noise associated with the transducer, measuring instrument or cables and this is a good measure of how sensitive a transducer is. In addition to the previously mentioned parameters, geometrical parameters for a transducer describe how the acoustic pressure generated by a transducer varies across the axial and cross-sectional fields of a transducer. These variations are illustrated below: Axial Beam Profile for an Ultrasound Transducer Cross – Sectional Beam Profile for an Ultrasound Transducer he detailed construction of an ultrasound transducer for medical applications involving the shaping of the piezoelectric material, matching layers, housing and backing materials etc is presently conducted using computational techniques such as Finite Element Modelling of ultrasound transducers through the use of software packages such as Ultrasim and other commercially available software. In the overall design, efforts have to be made to ensure that the overall design will be optimised so as to deliver a sufficiently high power of ultrasound into the tissue being imaged and as far as possible there is best possible sound impedance matching between the transducer and the scanned tissue. Design of the backing material in an ultrasound transducer is important because this design determines the ring down time of the transducer, which is critical for low noise and optimal axial resolution of the transducer. Trends in Transducer Design for Echocardiography Order Now. It takes less than 2 minutes. * Name * Email * Phone * Submit your essay question: (please give as much detail as possible) Only the simplest equipment for echocardiography will use a single ultrasound transducer and there is a trend towards design of echocardiography equipment which uses two or even three dimensional arrays of ultrasound transducers to provide superior quality 2 –D or 3-D computer generated pictures of the organ being imaged. Even the relatively simpler equipment being used these days has two or more ultrasound transducers fitted into the transducer probe. The array of transducers are capable of generating a shaped beam of ultrasound which can be appropriately focused using electronic digital signal processing techniques to provide better images and resolution. Although the relatively simple medical ultrasound scanners cost about ? 1000 per piece, reasonably decent transducer assemblies for a decent Philips or Toshiba ultrasound machines can cost ? 1500 for the transducer alone. Transducer arrays for two or three dimensional ultrasound imaging equipment can be much more expensive because of the large number of transducers that are employed in such imaging equipment. For better quality ultrasonic imaging to be possible, there is a requirement for enhanced bandwidth transducers, higher frequency transducer arrays and sophisticated digital signal processing circuits. There is also a trend towards transducer miniaturisation which will make intracavitary, intraurethral, or intravascular ultrasound (IVUS) investigation possible. The current imaging frequency range of 1 MHz to 15 MHz is expected to be increased to 20 MHz to 100 MHz and at these frequencies, microsonography devices using miniature ultrasound transducers with higher sensitivities are expected to provide much better and higher resolution images using catheter based transducers which are less then 2mm in diameter and are capable of being placed in veins. New ultrasound transducer materials are likely to provide transducers which are far more sensitive then those available presently and consume lower power. These transducers can be operated from battery powered portable equipment and there are indications in literature that with the availability of such devices, it is likely that the stethoscope will be replaced by miniature ultrasound equipment. New trends in ultrasound transducer construction are also moving towards composite transducer construction in which a composite of two piezoelectric materials is used to design the transducer. Ultrasound transducers are fairly rugged and the piezoelectric material does not loose its properties unless exposed to high temperatures approaching the Curie temperature for the material are reached or there are strong alternating or direct electrical fields opposing the direction of poling for the material. Mechanical stresses imposed on the piezoelectric materials should not exceed the specified limits and although the specified limits vary for different types of materials, mechanical stress in excess of 2. 5 MPa may be considered as likely to cause permanent damage. Ultrasound transducers are capable of being designed to operate in liquid mediums and the piezoelectric material does not react with water or gel. Conclusion Materials with piezoelectric properties such as lead titanate (PbTiO3) and lead zirconate (PbZrO3) lend themselves to being treated by poling to generate as well as detect ultrasound waves when subjected to alternating electric fields or mechanical stresses. Ultrasound transducers can be made out of these materials and these transducers can be designed for specified resonance frequencies for use in medical imaging. The detailed design of such transducers is an exciting and involving undertaking which is capable of being assisted by finite element simulations. Advances in transducer design involving the use of new materials, miniaturisation and the use of arrays of transducers promises to revolutionise medical imaging in the future by providing high resolution 3-D ultrasound images and the field is full of promise for device designers as well as computer engineers of the future. References/ Bibliography Web Sources 1. Abboud, Najib N et al. â€Å"Finite Element Modelling for Ultrasonic Transducers†. Weidlinger Associates Inc. SPIE Int. Symp. Medical Imaging 1998, San Diego, Feb 21-27, 1998. August 4, 2005. http://www. wai. com/AppliedScience/Software/Pzflex/Papers/pzflex-spie_mi98. pdf 2. Binder, T. â€Å"Three-Dimensional Echocardiography Principles and Promises†. Journal of Clinical and Basic Cardiology 2002; 5 (Issue 2), 149-152. August 4, 2005. http://www. kup. at/kup/pdf/1137. df 3. Brandt, Einar. â€Å"Segmentation Techniques for Echocardiographic Image Sequences†. University of Linkopings. 1998. August 4, 2005. http://www. imv. liu. se/klinfys/einar/publications/pdf_open/Ex1934. pdf 4. Bridal, Lori S et al. â€Å"Milestones on the Road to Higher Resolution, Quantitative, and Functional Ultrasonic Imaging†. PROCEEDINGS OF THE IEEE, VOL. 91, NO. 10, OCTOBER 2003. August 6, 2005. http://dei-s1. dei. uminho. pt/outraslic/lebiom/ultra/ultrasonic0123219 2. pdf

Never let me go book report free essay sample

Never let me go by Kazuo Ishiguro is about a group of human clones in a dystopian society raised only to become organ donors. The plot creates controversy. In the book, the clones are presented as sub-human and not permitted to be considered as equal to regular humans. Thus, it becomes acceptable for them to die a short life in order for others to live a longer one. It is here where we become aware of one theme, the poor treatment of those we believe to be beneath us in order to get ahead in the world. Another theme we can find in the book is that of conformity. We find that many times the characters seem accept their fate, without really putting up much of a struggle. They all seem to accept their fate as donors and the inevitability of their demise at 30 years old. This is especially present in today’s society, as many people would rather be seen as normal than abnormal and subsequently sticking to the status quo. We will write a custom essay sample on Never let me go book report or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page My favorite theme in the novel and the one I will be expanding on is the identity crisis the main characters and mostly the clones have throughout the book. This part of the novel I feel really relates to the real world and how a lot of individuals struggle to become their own person. Often looking in other places to blend into their personalities. These themes become coherent through Kathy’s eyes. As the main protagonist of the book, never actually becoming permanently attached to the situation many times only describing her observations and analysis of it. Then moving on to the next phase in her life. This theme resonates within me, since I have gone through the same identity crisis at some point of my life and often forget who I am in some circumstances. I also feel that the most part of the world has also experienced this. This does not only pertain to individuals, but can also be applied to countries as well. The main theme I’d like to discuss is the identity crisis experienced by many characters within the book. Kathys identity search is motivated by feelings of being alone in her own outlook. The sexual desires she experiences as young women upset her when she can not get validation from Ruth, another main character in the novel, that they are common. Ruth, seen as a social leader in the group, shows confidence but is in fact insecure of who she really is. Through Kathy’s eyes we perceive how Ruth often copies  her mannerism from older clones and television characters. Ruth relies much on others to define her own identity. Even Tommy, who acknowledges who he is, but has trouble believing it since he thinks others do not think the same. There are many passages in the book that implies this theme. Ruth states on page 120-121 in last paragraph, â€Å"There was something I noticed about these veteran couples at the cottages†¦ and this was how so many of their mannerisms were copied from the television†¦ the way they gestured to each other, sat together on sofas, even the way they argued and stormed out of rooms. † Even other characters notice this and try to fix the status quo. Miss Lucy, a guardian for the clones, tells them on page 80, â€Å"If you’re to live decent lives, you have to know who you are and what lies ahead of you, every one of you. † The first quote shows how people that do not know who they are and are hard press to find a way to individualize themselves may look to outside sources. The characters are in search of what makes them different from other clones and even the person they are cloned from. They hope to find a reason for their existence, much like citizens in the real world do. Countries also do this in a way. It could be by individual motivation or external influence. Smaller 3rd World Countries will try to model themselves after 1st world Countries believing they will share in the same success. This causes an identity crisis for their country. They have their own culture that separates them from the rest, but yet modeling themselves like another could alter the culture and lead to a lost in identity. This type of phenomena has happen in the past and could happen again. This topic brings up many questions in my mind. How the larger 1st world country influences the identity of a 3rd world country? I feel if the more powerful country really wanted too, they could have the 3rd world country model themselves after the 1st world. Which I think is what often happens, so they can more influence in structure of the world. How does one create their own identity is another question I would ask. If allowed to without any outside influences, what identity would a person or a country take on? I’d like to comprehend what having an identity really means.