Paleontogly Research Paper Example | Topics and Well Written Essays - 1750 words

Paleontogly - Research Paper Example The contemporary representation of this sexual dimorphism is that it is a â€Å"single, unidimensional phenomenon that is displayed to greater (e.g. gorillas, orangutans) or lesser (e.g. humans) degrees in the different primate species† (Oxnard, 1987, 2). Furthermore, it is commonly believed to be mainly related to variations in general size of the body between sexes (Levinton, 2001). The implication for evolutionary theory is, that human sexual dimorphism in the past must have been significantly greater than it is in the present day, possibly more like that in the living primates (Oxnard, 1987). Understanding the human ancestry is regarded as one of the challenges in exploring human evolution. Nonetheless, several fossil hunters appear to believe that this implies that their mission is to find the pieces of the exact human antecedent in the field (Elewa, 2004). Similarly, several laboratory examiners appear to believe that this implies that their mission is proving that a certain fossil relic is that ancestor (Serafini, 1993). Exploring human evolution, even in the mind of the public, appears to be this issue of moving from ‘missing’ to ‘found’ links (Oxnard, 1987, 2). The challenge appears to be the unearthing of ancestors. But what is the certainty of this undertaking? Even from a population as large and concentrated as that of any major metropolitan area, and over as many as hundreds of generations, the statistical changes of any particular individual ever becoming fossilized and found by a paleontologist millions of years later must be almost infinitesimal. How much less must be the chances of finding representatives of populations of perhaps only a few thousand, scattered over an area of the world as large as Africa or Asia, during periods of time measured in hundreds of thousands, even millions of years (Oxnard, 1987, 3). Once humans are thousand years ahead of a death, possibly tens of thousands of

BIOTECHNOLOGY Essay Example | Topics and Well Written Essays - 500 words

BIOTECHNOLOGY - Essay Example In females, angiogenesis also occurs during the monthly reproductive cycle (to rebuild the uterus lining, to mature the egg during ovulation) and during pregnancy (to build the placenta, the circulation between mother and fetus).† Angiogenesis is considered to be a form of tissue engineering since it meets the definition when it is used either synthetically or naturally to repair damage. That definition is, â€Å"Tissue engineering uses synthetic or naturally derived, engineered biomaterials to replace damaged or defective tissues, such as bone, skin, and even organs† (ATP, 2005). Diseases could be treated by turning angiogenesis â€Å"on† in the case of a severe injury or in the case of coronary artery disease. Disease could be treated by turning angiogenesis â€Å"off† in the case of cancer or diabetic blindness (The Angiogenesis Foundation, 2008). b. Compare necrosis and apoptosis. Describe how we could we take advantage of apoptosis in the treatment of disease? What would be the advantage(s) compared to traditional approached? Hint: Think cancer, hepatitis, etc. According to MedicineNet (2008, pg. 1), necrosis is â€Å"The death of living cells or tissues. Necrosis can be due, for example, to ischemia (lack of blood flow).† According to CancerTherapy.net, â€Å"the P53 gene causes the abnormal cells to commit suicide.   This is called aptosis.† The main difference between these two is that necrosis is not planned and that aptosis is programmed by the body. Aptosis is a necessary part of human life and is not a bad thing, whereas necrosis is very negative. Both occur naturally, but may be influenced by external factors. Aptosis may be used to treat diseases such as cancer or hepatitis since it is programmed cell death. It could kill off the diseased and bad cells without harming the good cells. Cancer occurs when abnormal cells in the body begin to grow out of control. It is caused by DNA damage. There are many

China and Inexperienced Industrial Revolution Essay - 1

China and Inexperienced Industrial Revolution - Essay Example Coal was at the time a better form of heat production. It gave constant, reliable amount of heat without giving out a lot of by-products as a waste (McCloskey 2010). The changeover was due to great innovation from individuals and group of people who skilfully devised ways to make work easier and create a better life for everyone (Chai 2011). Most of the innovations were involuntary and automatic, but additionally, there were others that founded through a series of experiments and exploit of science (Duiker and   Spielvogel 2011). This revolution, that is an industry based, commenced in Britain and a few years later it stretched to the United States of America, as well as Western Europe (Chai 2011). It grades one of the most significant turning points in the account of the history of the whole world. Nearly all aspects of the everyday life of the inhabitants of the planet were greatly influenced in one way or another (Nolan 2008). The thing that was mostly experienced was the sharp growth of the human population. The society at this period was exceedingly rural in nature. The revolution changed this to a much modern and urban society for most of the nations at that time (Beele 2002). Many countries experienced this mode of change that spread from the center of origin in Britain. China has had a dynamic economy in terms of its economy in the recent years (Nolan 2008). But why did it delay in achieving better industrialization that other states in Europe and other countries in the regions of the world were developing in the period? This paper is going to assess the reasons why China did not experience ‘industrial revolution’ between c. 1700 and 1949. According to Bayo r (2011), there was a delay in the industrialization in China until later in the century. In order to curb these problems, the country decided to raise its investment significantly together with the signing of a huge number of deals that included overseas companies that offered their services in the construction of some of the chief amenities for compound fertilizer manufacture, steel production and oil mining and processing in the refinery plant.These factors - availability of raw materials in Europe, a lot of richness acquired from the colonies, the widespread trade around the world, the presence of a unwavering form of government that offered support to the effectiveness of real establishments and was optimistic in scientific progress - made the European countries gain an upper advantage in revolutionising earlier in the century. China was not able to compete with these countries owing to the conditions which it was in that period.  

Annabel Lee as a Representative of Poe’s Poems Essay Example for Free

Annabel Lee as a Representative of Poe’s Poems Essay Annabel Lee as a representative of Poe’s poems about death of beautiful maidens Its always a little hard to separate the life of the legendary Poe from his works. In this case, there are some striking similarities. „Annabel Leeâ€Å" is the last complete poem written by Poe, published shortly after his death in 1849. Like many of Poes poems including The Raven, Ulalume, and To One in Paradiseâ€Å", it explores the theme of the death of a beautiful woman, â€Å"the most poetical topic in the world, according to Poe. In particular, although the poems stanzas have a somewhat irregular length and structure, the rhyme scheme continually emphasizes the three words me, Lee, and sea, enforcing the linked nature of these concepts within the poem while giving the poem a song-like sound. The work shows Poes frequent fixation with the Romantic image of a beautiful woman who has died too young unexpectedly. As indicated more thoroughly in his short story The Oval Portrait, Poe often associated death with the freezing and capturing of beauty, and many of his heroines reach the pinnacle of loveliness on their deathbed. The narrator, who fell in love with Annabel Lee when they were young, retains his love for her even after her death. Most people agree that Edgar Allan Poe wrote Annabel Lee about his departed wife, Virginia, who died of tuberculosis two years earlier. Some critics, however, contend that in the seventh line of the poem he states, I was a child and she was a child, and he certainly was no child in 1836 at twenty-seven when he married his thirteen-year-old bride. Maybe the poem is about an earlier love, or perhaps it is purely fictional, but addressing Annabel Lee as his life and his bride in line thirty-eight and writing it two years after his beloved young wifes death, it seems only logical that it is indeed written about her and is simply embroidered with a bit of poetic license. Local legend in Charleston, South Carolina tells the story of a sailor who met a woman named Annabel Lee. Her father disapproved of the pairing and the two met privately in a graveyard before the sailors ti me stationed in Charleston was up. While away, he heard of Annabels death from yellow fever, but her father would not allow him at the funeral. Because he did not know her exact burial location, he instead kept vigil in the cemetery where they had often secretly met. There is no evidence that Edgar Allan Poe had heard of this legend, but some insist it was his inspiration. The poem focuses on an ideal love which is unusually strong. In fact, the narrators actions show that he not only loves Annabel Lee, but he worships her, something he can only do after her death. The poem specifically mentions the youth of the unnamed narrator and especially of Annabel Lee, and it celebrates child-like emotions in a way consistent with the ideals of the Romantic era. Many Romantics from the eighteenth and nineteenth centuries viewed adulthood as a corruption of the purer instincts of childhood, and they preferred nature to society because they considered it to be a better and more instinctive state. Accordingly, Poe treats the narrators childhood love for Annabel Lee as fuller and more eternal than the love of adults. Annabel Lee is gentle and persistent in her love, and she has no complex emotions. He explains that angels murdered her. His repetition of this assertion suggests he is trying to rationalize his own excessive feelings of loss. In Annabel Lee the speaker argues in lines eleven and twelve that the angels were jealous of the happy couple: the winged seraphs of heaven coveted her and me. The envious angels, he insists, caused the wind to chill his bride and seize her life. However, he contends, their love, stronger than the love of the older or wiser couples, can never be conquered: And neither the angles in heaven above, Nor the demons down under the sea, Can ever dissever my soul from the soul Of the beautiful Annabel Lee. (lines 33-36) Unlike The Raven, in which the narrator believes he will nevermore be reunited with his love, Annabel Lee says the two will be together again, as not even demons can ever dissever their souls. The first time that death gets mentioned in the poem: A wind blew out of a cloud, chilling My beautiful Annabel Lee; (lines 15-16) The speaker doesnt say she died. Actually, he never uses the word death in this poem at all. The speaker maintains that this world of dream remains even after the death of his bride: For the moon never beams without bringing me dreams Of the beautiful Annabel Lee; And the stars never rise but I feel the bright eyes Of the beautiful Annabel Lee (33-6). The poems setting has several Gothic elements, as the kingdom by the sea is lonely and in an undefined but mysterious location. Poe does not describe the setting with any specificity, and he weaves a misty, romantic atmosphere around the kingdom until he ends by offering the severe and horrific image of a sepulchre there by the sea. At the same time, the nostalgic tone and the Gothic background serve to repeat the image of a love that outlasts all pposition, from the spiritual jealousy of the angels to the physical barrier of death. Although Annabel Lee has died, the narrator can still see her bright eyes, an image of her soul and of the spark of life that gives a promise of a future meeting between the two lovers. The image invoked by this poem is of enduring love. Both this everlasting love and the conclusion of the poem leave the speaker lying on the grave of his departed wife: And so, all the night-tide, I lie down by the side Of my darling-my darling-my life and my bride, In the sepulchre there by the sea, In her tomb by the sounding sea (37-41). As in the case of a number of Poes male protagonists who mourn the premature death of beloved women, the love of narrator of Annabel Lee goes beyond simple adoration to a more bizarre attachment. Whereas Annabel Lee seems to have loved him in a simple, if nonsexual, manner, the protagonist has mentally sacred her. He blames everyone but himself for her death, pointing at the conspiracy of angels with nature and at the show of paternalism inherent in her highborn kinsmen who came and bore her away, and he remains dependent upon her memory. While the narrator of the poem Ulalume suffers from an unconscious need to grieve and to return to Ulalumes grave, the narrator of Annabel Lee chooses ironically to lie down and sleep next to a woman who is herself lying down by the sea. Refferences: A History of American Literature: Then and Now, Radojka Vukcevic, Podgorica, 2005 The Cambridge Companion to Edgar Allan Poe, edited by Kevin J. Hayes. Cambridge University Press, 2002

Utilitarianism and Greatest Happiness Principle Essay Example for Free

Utilitarianism and Greatest Happiness Principle Essay Happiness Happiness: In one word, this concept exemplifies the American dream. People go to any means by which to obtain the many varied materials and issues that induce pleasures in each individual, and intrinsically, this emotion remains the ultimate goal, John Stuart Mill, a nineteenth century philosopher, correctly advocated the pursuit of happiness, and maintained the concept that above all other values, pleasure existed as the final destination, Mills hedonistic views correctly and rationally identified a natural human tendency, and his Utilitarian arguments strongly support the theory that above all else, happiness is the most important dream to be fulfilled. Upon researching for this paper, I came across a counter argument, which was based on metaphysics. Immanuel Kant, in Groundwork of the Metaphysics of Morals, defends his strong beliefs in the issue of a good will, and surfaces as MMs chief opponent on the topic of metaphysics, The issue diminishes to a clash between emotions and pleasures ve rses rationality and logic. Yet, what use is logic when the good agent is miserable? Mills stance within Utilitarianism exists as the more favorable of the two beliefs, for happiness exist as the one intrinsically favorable element, not an emotionless mind. The main defender of the Utilitarian system exists within the Greatest happiness Principle. Mill lived as a chief advocate of this concept, which supports the idea that a decision is morally correct as long as it increases and encourages pleasures and happiness. Kant, however, in his endless quest to remain separate from emotions and thrive only on logic, would argue that autonomy should be placed above happiness in a list of intrinsic values. A good will, however, does not comfort an individual in any way if happiness does not accompany this asset, Consider this example of a seemingly happily married couple. The wife in this duo is madly in love with her husband fiercely loyal, and completely happy with her marriage and children. The husband, however, as wrongfully strayed, and had a brief, but damaging affair behind his wifes back. Kant would argue that autonomy reigns over pleasure, and the woman should therefore want to be informed of her husbands adultery, Mill would greatly disagree. By revealing the secret of the past affair, the womans happy world would be instantly shattered. Her pride would diminish, her stability would fall apart, and the children especially would be forced to view a nasty side of their beloved father. In this case, individual control is greatly overshadowed by the need for happiness. The husband is no longer acting unfaithful and the family can easily continue to live in a happy realm, If the secret were to become uncovered, all members of this circumstance unavoidably would become terribly disappointed, Under the Greatest Happiness Principle, the wife should not be informed. Since happiness truly lives as the ultimate in human desires, sparing such immense amounts of pain truly is the logical choice, Mills argument prevails, and all those involved remain happy. Through this example, one can easily see that although autonomy is often a favorable feature, it does not overshadow the importance of happiness. One of the main arguments against Utilitarianism exist in the lack of apparent fairness. An advocate of the Kantian logic principle would argue that Mills belief system does not allow for equal treatment, When considering what is best for an entire society, however, it is necessary for certain individuals to endure suffering. The good of society remains the ultimate goal, and unfortunate pain is therefore inevitable, If young children are being killed in a certain community, the obvious good for this society is discovering and punishing the murderer. Especially when children are involved, people automatically demand prompt justice. The officials of this area have searched immensely for the accused, yet no leads have surfaced, and the community suddenly erupts with anger, they demand that someone be punished, As a Utilitarian, the police chief sees a window of opportunity. A drug dealer has recently been brought in on yet another drug selling offense, and the chief decides to coerce the invalu able member of society into confessing the crime at hand, By doing so, the community instantly reunites in support and a dangerous and deadly revolt is avoided, and a menace to society is right back where he would have been regardless of his confession: behind bars, Kant, however, would argue that logically, the chase for the true offender should continue. He would shun the emotional decision to make the whole society happy by ignoring the rational decisions. But since the community obviously chooses happiness over logic, Kants arguments are irrelevant. In addition, Kant believes in a decision making process completely separate from the natural human emotions, Such a demand is possible only for a character such as Star Treks Dr. Spock, for human emotions are as much a part of every day life as the decision making process itself. Logically speaking, therefore, Mills Utilitarianism arguments maintain the largest dose of validity. Other opponents to the philosophical viewpoint of Utilitarianism state that followers of this belief system often promote an ignorant lifestyle, They maintain that advocates of the Greatest Happiness Principle believe in the theory that ignorance is bliss, Again, such reasoning is quite faulty. Displaying the erroneousness of this statement can be done by examining the issue of AIDS, An opponent of Utilitarianism would say an Infected HIV victim would not want to be aware of his disorder, Such a belief is extremely incorrect. Mill and other Utilitarian are strong advocates of education, for with intelligence, greater levels of achievement and happiness can be obtained. A member of this belief system would rightly argue that being aware of the disorder could increase long-term happiness, for treatments and support from friends and family could greatly aid the victims fight against his or her alhnents, Mills therefore strongly support education systems and believe in making society as a whole as happy as possible. In the case of the AIDS victim, a Utilitarian would also support the notification of the disorder to the victim in order to spare others of contracting the virus, The happiness of the majority would not be increased by an unknowing HIV carrier spreading the disease to other defenseless individuals, Utilitarianism clearly is not a ignorant way to live, and the Kantian philosophy of ignoring the irrational system of emotions cannot refute this standard. Without happiness, the other opportunities and necessities lose nearly all levels of importance. A true Utilitarian supports only those concepts that promote the highest levels of pleasures, and as Mill states, encourages only those actions that promote real happiness, From a Kantian viewpoint, rationality and the possession of a good will remains the most important element, but even someone with the truest and most logical of intentions can easily exist in a realm of pure depression. The one link that exists between these opposite belief systems is the concept that, all decisions should be made outside of ones personality. The key is that Kant said this decisions should be made without any regard for human emotions, A request of this magnitude is a part of a utopian society only, for ignoring ones emotions is an illogical assumption in itself, If your child and wife are both dying, deciding which one to save cannot be made without some emotional influence, Utilitarianism allows for the emotional side of life but requests only that the Greatest Happiness Principle be strictly followed. Any truly decent human being naturally follows such a request every day, Decisions are made based on the greatest level of happiness, That way, the largest majority of people benefit, and the greatest amount of happiness is achieved. Yet as Kant believed, a more morally correct decision lies at the heart of every dilemma. How does one decide who is morally more correct to save in an instance where two cherished loved ones are passing away, and only one individual may be saved? And even more importantly, how does one do so without regard emotions? I personally feel that living strictly by the doctrine of Kantian philosophy is completely impossible. Being a Utilitarian and hedonist, such as Mill, makes more sense to me.

Magnetic Resonance Imaging (MRI) Physics Instrumentation

Magnetic Resonance Imaging (MRI) Physics Instrumentation TITLE : MRI IMAGE ARTIFACTS MOHAMAD AL-HAFIZ BIN IBRAHIM Name of Student: Mohamad Al-Hafiz bin Ibrahim TABLE OF CONTENTS (Jump to) LIST OF FIGURES 1.0 INTRODUCTION 2.0 MRI ARTIFACTS 2.1 RF leakage 2.2 Aliasing 2.3 Patient motion 2.4 Gibbs Truncation 2.5 Chemical Shift 2.6 Magnetic Susceptibility 2.7 Flow Motion 3.0 CONCLUSION 4.0 REFERENCES LIST OF FIGURES Figure 1: Zipper Artifact may appear as horizontal line across the image Figure 2: The part of the body that outside the FOV is mismapped within the FOV. Figure 3:The appearances of ghost lines at the anterior to the abdominal wall Figure 4: Image shown the effect of head movement or motion during MR scanning Figure 5: Bright and dark lines are visible in image Figure 6: Arrow show dark line at the interface of fat and water . Figure 7: MR image shown massive distortion of magnetic field . Figure 8: (a) CSF pulsation-related artifact in the phase encoding direction in T2-weighted image while (b) show reduction of flow artefact 1.0 INTRODUCTION Magnetic Resonance Imaging (MRI) is one of the medical imaging and diagnosis technique which widely used due to its capability to produce high resolution of cross- sectional anatomical images and high tissues contrast. Eventhough MRI has various advantageous features, but still there are numerous sources of artifacts either patient-related, signal processing-dependent and hardware (machine) related (Erasmus, Hurter, Naudà ©, Kritzinger, Acho, 2004). Definitely, artifacts can degrade the image quality and may mimicking pathology or obscure the abnormalities which can lead to misdiagnosis of MRI images. The MRI artifact can be defined as a structure or feature appearing in MRI image produced by artificial means which is not originate within the scanned object (Erasmus et al., 2004). Commonly, MRI artifacts can be caused by RF leakage, aliasing, patient motion, Gibbs, truncation, chemical shift, magnetic susceptibility and flow motion. 2.0 MRI ARTIFACTS 2.1 RF leakage Cause This artifact also known as Zipper artifact. It occurs when there are leakage of RF or electromagnetic energy generated from certain equipment into MRI system (Stadler, Schima, Ba-Ssalamah, Kettenbach, Eisenhuber, 2007). This extrinsic RF came at a certain frequency then interferes with MRI signal produced by patient. The potential sources of the extrinsic RF are due to penetration of the RF into the shielded scanning room especially when the door is open during images acquisition (Ruan, 2013). After that, the RF will be picked up by the receiver chain of the image sub system (Zhuo Gullapalli, 2006). This RF perhaps generated by radio, illumination or electronic device such as monitoring equipment in the surrounding (Stadler et al., 2007). Remedy In order to overcome this artifact, the operator should identified and eliminate the possible source of the penetration. It can be done by ensure the door of the MR room remain closed during scanning, use only MR compatible MR monitor equipment, and remove the external RF source from the surrounding (Ruan, 2013). Figure 1: Zipper Artifact may appear as horizontal line across the image (Allen, n.d.). 2.2 Aliasing Cause Aliasing or wrap around artifacts can be describe as an artifacts that caused by anatomy that lies outside of field of view (FOV) mismapped within the FOV (Westbrook, Roth, Talbot, 2011). This is because of improper selection of parameter in MR systems especially FOV. The FOV in MRI means the anatomical area that should be covered or imaged during scanning (Morelli et al., 2011). When the selected FOV is smaller than the size of area that should be imaged means the data are under-sampled (Ruan, 2013). Therefore, there are high chances for signals from the outside FOV falsely detect then create an interference with signal within FOV and encode on the reconstructed images thus ‘wrap around’ to the opposite side of image which become aliasing artifacts (Erasmus et al., 2004). Westbrook et al., (2011) state that aliasing artefact can happen along frequency encoding axis (frequency wrap) and phase encoding axis (phase wrap). Remedy Basically, this aliasing artifacts can be eliminated through increase the sampling rate or oversampling along the frequency direction (Westbrook et al., 2011). However, high pass and low pass filter should be used as well in order to filter out frequency outside the FOV which can increase noise in image (Hiroshi, Schlechtweg, Kose, 2009). Besides that, selection of receiver coil which unable to excite or detect the signals from anatomical tissues that lying outside the FOV also important to minimise the artifacts (Ruan, 2013). Lastly, No Phase Wrap (NPW), Phase oversampling or Fold Over supression techniques is also preferred to avoid aliasing artefact by oversamples in phase direction, thus, the phase curve get to extends and cover wider signal producing structures (Westbrook et al., 2011). Figure 2: The part of the body that outside the FOV is mismapped within the FOV and located at the opposite side of the image (Prashant, 2014). 2.3 Patient motion Cause Patient motion artifact is a very most common artefact in MRI. It is caused by movement of anatomical structure during imaging sequence (Zhuo Gullapalli, 2006). There is a broad range of examples of structure movement such as heart or arterial pulsations, respiration process, peristalsis, tremor (Parkinson’s disease) and gross movement of patient (Stadler et al., 2007). Hence, if there is a scanned anatomical part moved during the scanning, the phase gradient cannot predict and encode the signal, thus, that structures will be misplaced in phased encoding direction. As a result, it will causes MR images shown the appearances of mismapping, blurring and ghosting artefact within it (Westbrook et al., 2011). Remedy There are several ways to eliminate or avoid the patient motion artifacts. The remedies are nullifies signal by applying pre-saturation pulses over the area which have potential to produce artifacts (Stadler et al., 2007). This way is more effective to prevent ghosting during patient swallowing. Besides that, Westbrook et al (2011) proposed that attaching a set of bellows over patient’s chest in respiratory compensation which is also known as respiratory ordered phase encoding (ROPE) might help to minimize ghosting in longer sequences while in short sequences, cooperation from patient to hold their breath during scanning is preferred. Next,cardiac gating also plays role in reducing this kind of artefact. For example, electrocardiogram (ECG) gating used to monitors cardiac motion that trigger the excitation pulse. Hence, each excitation pulse in each slice can be timed and acquired at the same phase of cardiac cycle (Westbrook et al., 2011). In the other hand, asking for patient cooperation for keeping still, clear explanation about procedures, and optimize the patient’s comfortability are important to make them immobilize during scanning (Hiroshi et al., 2009). Figure 3:The appearances of ghost lines at the anterior to the abdominal wall indicate as motion artifact because of breathing (Zhuo Gullapalli, 2006). Figure 4: Image shown the effect of head movement or motion during MR scanning (Hornak, n.d.) 2.4 Gibbs Truncation Cause Truncation artefact also can be called as Gibbs Ringing artefact (Czervionke, Czervionke, Daniels, Hauhgton, 1988). Its happen as result of It is causes by abrupt undersampling of data that results in incorrect representation of high and low signals interfaces (Westbrook et al., 2011). That problems lead to visibility of fine lines in MR image and also respectively caused by incomplete digitization of the echo (Ruan, 2013). However, according to Erasmus et al.,(2004), alternating dark and bright lines may visible in image due to a sharp transition in signal intensity. Remedy In order to correct this type of artefact, there are several ways that can be used. For example, increase the matrix size, 256 x 256 instead of 256 x 128 (Westbrook et al., 2011). Next, applying various filters to k-space data before Fourier transform also should be considered (Erasmus et al., 2004). Besides that, provide more phase encoding steps also preferred to make truncation or gibbs artifacts less intense and narrower (www.mr-tip.com, n.d.). Figure 5: Bright and dark lines are visible in image parallel and adjacent to the outer convexity of calvaria (Prashant, 2014). 2.5 Chemical Shift Cause This type of artifact commonly found in MRI image of abdominal and spine imaging. Since fat and water each consist of hydrogen protons but different combination of molecules, fat contain hydrogen binds with carbon,while in water, hydrogen combine with oxygen (Westbrook et al., 2011). Hence, that different chemical environment exist shown that there are different precession frequency between fat and water which fat has lower precessional frequency rather than water (Erasmus et al., 2004). Based on the Larmor equation, precessional frequency is proportional to the strength of magnetic field (Westbrook et al., 2011). Therefore, this chemical shift can become artifact due to that difference of the precessional frequency between fat and water at higher field of magnetic strengths during the frequency encoding or slice-select directions (Ruan, 2013). That frequency is basically used to encode their spatial positions, thus, any chemical shift can lead to spatial misregistration of the MR si gnal (Morelli et al., 2011). MR images will show the bright or dark outlines at fat-water interfaces as the artefact. Remedy To avoid this artefact , a few remedies should be considered such as perform scanning at low magnetic field strength, increase the receive bandwidth in keeping with good signal-noise-ratio (SNR) (Westbrook et al., 2011) . It is also suggested to use minimum FOV as possible. Lastly, swapping phase and encoding direction also may useful to reduce this artefact (Hiroshi et al., 2009). Figure 6: Arrow show dark line at the interface of fat and water indicate as chemical shift artefact (Javan, Rear, Machin, 2011). 2.6 Magnetic Susceptibility Cause Susceptibilty can be refer as characteristic of substance which be magnetized when exposed to magnetic field (Gary, n.d.). MRI physics explain magnetic susceptibility artifacts normally happens because of substance or material especially ferromagnetic materials and also at air-tissues interface which have different degree of magnetic susceptibility that can distort the external magnetic field when placed in large magnetic field. Besides that, the differences also lead to magnetic field inhomogeneity at the scanner region resulting in spins dephase faster and frequency shift between surrounding tissues (Zhuo Gullapalli, 2006). Artifacts in the image will appear as bright and dark areas with spatial distortion of anatomical structures (Stadler et al., 2007). Remedy Generally, these artifacts can be reduced by ensure all metal objects that attached to the patient has been removed before the scan. Next, spin echo sequences are more preferred to be used instead of gradient echo because it use 180 ° RF rephasing pulse which ideal at compensating for phase differentiation between fat and water (Westbrook et al., 2011). Since fast spin echo techniques also contribute in reduction of this type of artefact, hence, short TE is used along with spin echo (Stadler et al., 2007). Metal Artefact Reduction Sequence (MARS) technique can be used in order to minimize the size and intensity of this artifact which developed by magnetic field distortion by introducing an additional gradient following the slice gradient during frequency encoding gradient is used (Olsen, Munk, Lee, 2000). Figure 7: MR image shown massive distortion of magnetic field due to implanted dental retention system (Schubert, 2012). 2.7 Flow Motion Cause Flow artefact can be categorized as one kind of motion artefact which mainly caused by natural motion of liquids such as blood or cerebrospinal fluid (CSF) in the body. For example, hydrogen nuclei in blood flow within the scanned slice may trigger excitation from an incoming RF pulse, however, the signal perhaps cannot be readout due to possibility of that flowing blood have left the slice (Hiroshi et al., 2009). As a result, vessels image appear empty or low signal intensity (less bright). Generally, there are reasons of low signal intensity such as intravascular signal void by time of flight effects, first echo dephasing and fast flow (Hiroshi et al., 2009). Nevertheless, this artifacts also can appear bright or high signal intensity. This is because of the slow blood flow (flow related enhancement), even echo rephrasing and diastolic pseudogating (Hiroshi et al., 2009). Remedy The preferred solutions as remedies for flow motion artifacts are by reduction of phase shifts using flow compensation in order to produce gradient moment nulling, suppress the blood signal by apply saturation pulses parallel to slices and synchronization of imaging sequences with cardiac cycle using cardiac triggering (Zhuo Gullapalli, 2006). Figure 8: (a) CSF pulsation-related artifact in the phase encoding direction in T2-weighted image while (b) show reduction of flow artefact with gradient moment nulling (Morelli et al., 2011). 3.0 CONCLUSION It is important for all operators, radiologist and engineers in MRI are able to recognize common MRI artifacts because there are a broad of range of cause that contributing to artefact. Eventhough, artifacts are unable to be totally eliminated but it can be minimized or avoided with specifics remedies in order to improve the MR image quality (Morelli et al., 2011). Therefore, basic knowledge of MRI artifacts should be learned and all MRI system operators should familiar with their MRI unit in department. 4.0 REFERENCES Allen, E. D. (n.d.). Zipper and Related Artifacts. Retrieved May 9, 2015, from http://mri-q.com/zipper-artifact.html Czervionke, L. F., Czervionke, J. M., Daniels, D. L., Hauhgton, V. M. (1988). Characteristic features of MR truncation artifacts. American Journal of Roentgenology, 151, 1219–1228. http://doi.org/10.2214/ajr.151.6.1219 Erasmus, L. J., Hurter, D., Naudà ©, M., Kritzinger, H. G., Acho, S. (2004). REVIEW ARTICLE: A Short Overview of MRI Artefacts. SA Journal of Radiology, 8(August), 13–17. http://doi.org/10.1021/jp1019944 Gary, P. L. (n.d.). What is MRIà ¢Ã¢â€š ¬Ã‚ ¯? Magnetic Resonance Imaging ( MRI ). Hiroshi, Y., Schlechtweg, P., Kose, K. (2009). Magnetic Resonance Imaging. Imaging of Arthritis and Metabolic Bone Disease:Expert Consult Online and Print, p34–48. http://doi.org/10.1017/CBO9780511549854.007 Hornak, J. P. (n.d.). The Basics of MRI: Image Artifacts. Retrieved May 9, 2015, from https://www.cis.rit.edu/htbooks/mri/chap-11/chap-11.htm Javan, R., Rear, J. R. O., Machin, J. E. (2011). Fundamentals Behind the 10 Most Common Magnetic Resonance Imaging Artifacts with Correction Strategies and. European Society of Radiology, 1–78. http://doi.org/10.1594/ecr2011/C-1248 Morelli, J. N., Runge, V. M., Ai, F., Attenberger, U., Vu, L., Schmeets, S. H., †¦ Kirsch, J. E. (2011). An image-based approach to understanding the physics of MR artifacts. Radiographicsà ¢Ã¢â€š ¬Ã‚ ¯: A Review Publication of the Radiological Society of North America, Inc, 31, 849–866. http://doi.org/10.1148/rg.313105115 Olsen, R. V, Munk, P. L., Lee, M. J. (2000). 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Psychology Essays Amnesic Syndrome Amnesia

Psychology Essays Amnesic Syndrome Amnesia Amnesic Syndrome Amnesia Hypothetical amnesic syndrome single case intervention: Clive Wearing Amensia Amnesic Syndrome Amnesia is a general, classically used term essentially to describe the partial or total loss of memory. Due to the complexity of human memory functioning, several different types of amnesia exist, in particular, Amnesic Syndrome (A.S.) which, in its most coherent, is a cluster of amnesic symptoms. Amnesic syndrome is characterised by the permanent memory impairment which can occur in anterograde form the syndrome’s defining feature and retrograde form. Unlike general amnesic condition, the diagnostic origin of A.S. excludes degenerative disorders, for example Parkison’s; transient amnesias; and psychogenic disorders. The aetiology of A.S. include those brought on by (direct or indirect) injury to the brain and damage to any number of neuroanatomical locations responsible for memory functioning, namely subcortical areas the diencephalon, a major region of the brain that includes the third ventricle, thalamus, hypothalamus, and pituitary gland; and also cortical areas covering the medial surfaces of the temporal lobe, especially the hippocampus. Understanding the effects of this damage is possible in no small part to using the modular memory system approach and observing the pattern of preservation and loss in other words, what the patient is and is not capable of. It is understood that long term memory (LTM) is structured as to distinguish declarative memory of what we know to be as ‘fact’ from less explicitly accessible memory functioning such as those implicitly stored and that which is not pertaining to factual information, referred to as non-declarative memory. Aggleton Brown (1999) reported that both the subcortical and cortical locations, as mentioned above, are components of the same memory system concerned with the explicit, declarative memory. This declarative memory is made up of the subcategories episodic personal events one experiences; and semantic relating to vocabulary, language ability and object recognition. It is therefore clear that the damage suffered to part or all of these areas of the brain would largely affect the declarative memory of a patient, whilst leaving the implicit, non-declarative memory relatively unimpaired. This is true in cases of both anterograde and retrograde amnesic syndrome. There are also several non memory related characteristics of amnesia which appear in A.S., degrees of which depend on the origin of the syndrome, for instance the location of injury and which parts of the brain are affected. Characteristics include orientation, intellectual deficit and confabulation. Confabulation, sometimes referred to as ‘islands of confabulation’, describes the attempts made to rationalise memories (or voids in memory) in order to make sense to the self and others, which may involve the production of false information. Single Case: Clive Wearing Clive Wearing is considered by many to be the most sever case of amnesia. Once a renowned and eminent musician and musicologist, Clive was struck by an inflammatory brain infection herpes encephalitis, in March of 1985. An initial CT and subsequent MRI scan reported major and significant damage to the left temporal lobe, also extending into the inferior and posterior frontal lobe as well as damage to the medial side of the right temporal lobe. This was accompanied by indications of involvement of the left lateral ventricle and third ventricle part of the diencephalon, along with the almost complete destruction of the hippocampus. It is believed that these areas of damage are the cause of several behaviours Clive Wearing exhibited and continues to do so today. It is well reported that Clive (CW) has severe episodic memory dysfunction, resulting in retrograde amnesia for virtually the whole of his adult life and much of his childhood along with anterograde amnesia demonstrated by his incapacity for explicit learning. CW has become synonymous for his moment to moment consciousness whereby the period of seconds is lost in a perceptual time void and where perceived information is lost as soon as his eyes close quite literally in a blink only to be confronted with the experience of a completely new ‘awakening’ repeated many times. CW’s semantic memory, though generally preserved in A.S., showed evidence of impairment as he is unable to produce object names, define words and comprehend written material, instead lending himself towards confabulation. CW’s pattern of deficits in declarative memory can be explained by the neurological damage that he suffered. The major damage to the hippocampus (relatively destroying it) is the most likely cause of the severity of his amnesia, whereas the retrograde amnesia is attributed to the diencephalic damage, and semantic memory impairment adheres to the more widespread temporal lobe damage. Functioning and Indications for Intervention Contrary to CW’s deficit in declarative memory, his non declarative memory is left relatively unimpaired. There are many reports of CW’s implicit memory functioning, most notably his procedural memory for reading, playing, conducting and singing music which are practically preserved. Clive has, on more than one occasion, denied seeing a piece of music or even playing the piano, only to (when directed), sit down and play the piece and add â€Å"I remember this one†. Additional evidence for CW’s implicit memory comes from the first few years of his condition where he began to abbreviate his questions, he would only need to ask his wife ‘How long?’ to be understood as to what was meant, ‘How long have I been ill?’ suggesting an awareness, on some level, that the question has been asked before, as well as the knowledge of the fact that she knows what it means. Evidence for implicit learning comes from the report after eighteen months of his new home, where he has been taken for daily walks to feed the ducks, now asks ‘do the ducks want their tea?’ when prompted to put on his coat, ceasing to ask how long he has been ill a seven-year obsessive habit. Though his apparent disorientation, he has also gained other (purely) implicit memories like the layout of his residence where he is able to go to the bathroom, kitchen and dining room unsupervised. However, if he stops, gets distracted, or thinks en route he becomes lost. And though not able to describe his residence, his wife Deborah has reported how he will undo his seat belt and offer to get out and open the gate as they draw near. He is unable to explicitly identify the locations but is capable of action. The role of music in CW’s implicit learning is certainly an interesting one, as not only is his procedural memory relatively unimpaired but he is also capable, providing someone puts the music before him to get him into action, of learning and practicing new pieces. It is also reported that he also hummed something which he had not played for half an hour. This discovery is of great relevance to the following section on intervention as it suggests that this is could be down to rehearsal of it subvocally, perhaps reflecting use of the phonological loop process in memory encoding. Broca’s area is a relatively contained section in the inferior frontal gyrus of the frontal lobe and is namely responsible for the production of speech and sounds. There is little evidence to suggest of a deficit in CW’s ability to produce speech and sound and therefore any relative damage to this area, which in turn enables the seeming subvocal rehearsal that has been reported. Seeing as CW appears to have some phonological functioning and fairly preserved implicit memory, this seems a rational starting point for rehabilitative intervention. Proposed Intervention Whereas in previous clinical approaches where rehabilitation was usually based on a broad range of therapies (CBT, psychotherapy, etc), neuropsychological therapy tackles small areas either to test theories or to increase the understanding of a particular subject area. In the case CW, it is the impairment experienced involving disorientation that will be the focal point of this intervention. The intervention will operate at the level of impairment the specific problem being disorientation. In terms of the intervention mechanism restoring or reinstating the original function this seems very unlikely to be possible. The alternative therefore, is to instate an intervention mechanism that will utilise and develop existing capacities with the use of external aids and strategies to overcome the problem. Implicit learning of routes through basic repetition would not be recommended in this case. Instead, it would be preferable to use the available existing/surviving capacities (i.e. subvocal rehearsal and procedural memory) as this approach, if sufficiently effective, could be transferred for other possible applications in different situations. CW’s procedural memory of music lends itself extremely neatly to the notion of journeys and routes due to its formulative and progressive nature. CW’s wife Deborah speaks of the â€Å"momentum of music† where it is said that music, much like any route has steps, phrases, beginnings and ends (Wearing and Wilson, 1995). In an article, author and neurologist Oliver Sacks (2007) provides a compelling narrative of this momentum indicating the link of memory and melody: There is not a process of recalling, assembling, recategorizing, as when one attempts to reconstruct or remember an event or a scene from the past. We recall one tone at a time, and each tone entirely fills our consciousness yet simultaneously relates to the whole. It is similar when we walk or run or swim—we do so one step, one stroke at a time, yet each step or stroke is an integral part of the whole. Indeed, if we think of each note or step too consciously, we may lose the thread, the motor melody. (Sacks, 2007) In normal automatisation of procedural information which can range from making a cup of tea to driving a vehicle, the memory trace of each encounter is encoded and strengthened with each practise so that in future cases relevant information is retrieved quickly. In the case of CW this report suggests that a method of auditory mnemonic reduction encoding be used, set up with vanishing retrieval cues, gradually removed so as to encourage the strengthening of the mnemonic information in an errorless learning environment. Encoding with visual and auditory mnemonics has been shown to be very effective in the development of creating links and encoding memorable retrieval cues (e.g. Burrows Solomon, 1975; Sharps Price, 1991; Haan et al., 2000) and provides a supported approach to the proposal intervention. The use of vanishing cues enables a ‘length’ of information to be divided into a number of relevant cues that are subsequently and gradually removed, thus resulting in a scope of learnt information which may require very few or even no recall cues. Errorless learning has been effective in a number memory-impairment cases (e.g. Tailby Haslam, 2003; Page et al., 2006), where errorless learning employs a 100% correct response technique in strengthening memory traces. Single Case Design Proposal Neuropsychological intervention of any sort would usually naturally happen once the patient starts to demonstrate gaining a sense of normal functioning, that is after the initial period of spontaneous recovering has occurred, as initiating intervention during this time of innate recovery is not suggestible results may show absent or false improvement. In the case of CW however, this is not an area of concern. The intervention will operate with auditory mnemonics and vanishing cues. It will be a tri-level multiple baseline design as to assess its effectiveness across and between situations. Three routes / journeys will be decided upon in relation to CW’s most important or habitual preferences. For the purpose of this proposal the three routes will be that from his room: (a) to the dining room (b) to the hall the location of his piano and (c) outside via fire escape route. The initial phase of the intervention will be reporting the baseline measurement for each route. This will be the amount of time it takes CW to get from his room to the each of the destinations, observations will also be made as of any experiences of disorientation and if so note down where along the route and how often they occur, using several measures maximise the stability of the assessment as they will be compared with the results of the intervention phase. The measurement phase will continue for 1 month before the first-level intervention is employed. The second phase will start with the implementation of the first-level intervention for the first situation (a). The route that CW takes will be marked off using posters showing a coloured symbol (e.g. a green triangle) at significant points. CW will also have accompanied with him a device that allows him to play a single relatively short melody, one that he is familiar with. This will then be set to repeat, although it is assumed that one piece played from start to finish should last for more than sufficient time than it takes him to reach his destination in this case the dinning room. During this time CW is encouraged to hum or sing the melody out loud. This first-level intervention for the first situation will continue for 2 months and measurements will be taken following the same concept as those in the baseline phase. Following this will be the second-level intervention where the visual cues (green triangles) are gradually removed in suitable order so that there are no significantly unequal ‘gaps’ in cues along the route. CW will at this time still be encouraged to play and hum to the chosen melody along the route. This phase will be carried out over a total of 2 months, again, whilst measurements are taken. The third-level intervention will entail CW not having access to the melody playing device, however he will still be encouraged to hum or sing what could be referred to at this point as the ‘dinning room melody’. Measurements will be carried out as previously done. This stage will continue for 1 month and then conclude the second phase of the intervention. After which the additional two routes will be initiated in sequence following the example of the first situation. A summarised list of the programme will look as follows. Phase 1 Multiple baseline recording Measurements are taken across all situations (length: 1 month) Phase 2 Intervention of first situation (a) to dinning room Level 1 melody played with cues (length: 2 months) Level 2 cues gradually removed (length: 2 months) Level 3 melody device removed (length: 1 month) Phase 3 Intervention of second situation (b) to hall Level 1 melody played with cues (length: 2 months) Level 2 cues gradually removed (length: 2 months) Level 3 melody device removed (length: 1 month) Phase 4 Intervention of third situation (c) fire escape route Level 1 melody played with cues (length: 2 months) Level 2 cues gradually removed (length: 2 months) Level 3 melody device removed (length: 1 month) Phase 5 Assessment of results The appendix includes graphs that represent three possible outcomes of the intervention. The first in Appendix 1 demonstrates a successful intervention, evaluation of which will be discussed below. The second in Appendix 2 illustrates a clearly unsuccessful intervention whereas the third in Appendix 3 illustrates the possible results of a temporary positive effect of intervention followed by a decline in improved performance. Signs that the intervention is successful will be a significant improvement in performance compare with baseline measurements. That is not necessarily to say that route-taking will be quicker, but that incidence of disorientation would have been significantly reduced. The proposed evaluation of the intervention will consist of checking whether it has been successful in its aim and the reasons behind this outcome. If an improvement has been demonstrated it must be examined as to the source of change. Sources of change vary in terms of the circumstances of the case, for instance spontaneous recovery and innate brain recovery at this stage of the condition is highly unlikely and would have been captured in baseline measurements. General treatment effects i.e. what happens in CW’s home such as care and interactions are also another source of change which, in other cases may be an affect. The length of the intervention may allow changes in circumstance to affect performance. Major changes of this sort are unlikely however it would still be advisable to report any relevant changes. If an improvement has not been affirmed the intervention will be seen as not effective. This doesn’t necessarily that the theoretical basis was at fault, the judgement of available case information may not have been sufficient. Problematic methodology could also be a cause. If the phases (and containing levels of aid) of the intervention were not carried out for long enough, or correctly the effectiveness of the proposed intervention would be compromised. Providing the intervention was successful and improvement was made, it would be critical to examine the genuine extent to which the person’s life had changed for the better. This could take the form of improved functioning, increased independence and improved sense of well-being. It would also be relevant to examine the capacity to generalise the principle for application in other situations. The nature of the proposed multiple baseline design allows, on demonstration of positive results, that the intervention could be applied to similar situations and even for use in other cases of similar patients with A.S. References Aggleton, J. P., and Brown, M. W. (1999) Episodic memory, amnesia, and the hippocampal-anterior thalamic axis. Behavioral and Brain Sciences. 22 (4). pp. 425-440 Burrows, D. and Solomon, B. A. (1975). Parallel scanning of auditory and visual information. Memory and Cognition. 3 (4). pp. 416-420. Haan, E. H. F., Appels, B., Aleman, A. and Postma, A. (2000). Inter-and intra-modal encoding of auditory and visual presentation of material: Effects on memory performance. The Psychological Record. 50 (3). pp. 577-86. Page, M., Wilson, B. A, Shiel, A., Carter, G. and Norris, D. (2006) What is the locus of the errorless-learning advantage? Neuropsychologia. 44 (1). pp. 90-100 Sacks, O. (2007) The Abyss; A Neurologists Notebook. The New Yorker. New York. 83 (28). pp.100. Sharps, M. J. and Price, J. L. (1991). Auditory imagery and free recall. The Journal of General Psychology. 119 (1). pp. 81-87. Tailby. R. and Haslam C. (2003) An investigation of errorless learning in memory-impaired patients: improving the technique and clarifying theory. Neuropsychologia. 41 (9). pp. 1230-40. Wilson, B.A. and Wearing, D. (1995) Prisoner of Consciousness: A state of just awakening following Herpes Simplex Encephalitis, In Campbell, R. Conway, M. Broken Memories: Neuropsychological Case Studies. Oxford: Blackwell. pp. 15-30