A pathology

In statistical terms, a perceptual improvement is therefore obtained if the amplitude distribution in the filtered signal (image) is more concentrated around zero than in the raw data (contrast enhancement). A more concentrated amplitude distribution generally means smaller entropy. Thus, from an operator perception point of view, interesting results should be obtained if the raw data can be filtered to yield low entropy amplitude distributions. However, one should note that the entropy can be minimized by means of a (pathological) filter which always outputs zero or another constant value. Thus, appropriate restrictions must be imposed on the filter construction process. 

As described at the end of section Al.6.1. in nonlinear spectroscopy a polarization is created in the material which depends in a nonlinear way on the strength of the electric field. As we shall now see, the microscopic description of this nonlinear polarization involves multiple interactions of the material with the electric field. The multiple interactions in principle contain infomiation on both the ground electronic state and excited electronic state dynamics, and for a molecule in the presence of solvent, infomiation on the molecule-solvent interactions. Excellent general introductions to nonlinear spectroscopy may be found in [35, 36 and 37]. Raman spectroscopy, described at the end of the previous section, is also a nonlinear spectroscopy, in the sense that it involves more than one interaction of light with the material, but it is a pathological example since the second interaction is tlirough spontaneous emission and therefore not proportional to a driving field... 

Drug addiction is a pathological behavioral syndrome that has to be strictly separated from physical dependence. An individual can be physically dependent on a drug without being addicted to it and vice versa. Transient neuroadaptive processes underlie physical dependence and tolerance to a drug, whereas persistent changes within specific neuronal systems underlie addictive behavior. 

In the past number of years a number of studies have shown that in a variety of diseases there is a significant oxidation of Met residues to Met(O) in specific proteins that results in a loss of biological activity. These diseases include cataracts, rheumatoid arthritis, adult respiratory distress syndrome and emphysema. The most convincing evidence that Met(O) in proteins may be involved in the etiology of a pathological condition comes from studies with a-l-PI. It is well accepted that a-l-PI is inactivated upon oxidation of its Met residues. A decreased activity of a-l-PI in lung tissue that would result in an increased elastase activity has been associated with pulmonary emphysema. In patients who have a... 

For a variety of reasons, lipid—mainly as triacylglycerol—can accumulate in the hver (Figure 25—6). Extensive accumulation is regarded as a pathologic condition. When accumulation of lipid in the Ever becomes chronic, fibrotic changes occur in the cells that progress to cirrhosis and impaired liver function. 

MasUah E, Heaton RK, Marcotte TD, EUis RJ, Wiley CA, MaUory M, Achim CL, McCutchan JA, Nelson JA, Atkinson JH, Grant I (1997) Dendritic injury is a pathological substrate for human immunodeficiency virus-related cognitive disorders. HNRC Group. The HIV Neurobehavioral Research Center. Ann Neurol 42(6) 963-972... 

The body possesses an efficient natural defence mechanism which restricts microorganisms to areas where they can be tolerated. A breach of this mechanism, allowing them to reach tissues which are normally inaccessible, results in an infechon. Invasion and multiplicahon of the organism in the infected host m result in a pathological condihorr, the clirrical entity of disease. 

One fundamental property of an animal s immune system is that it does not normally react against its own body constituents, i.e. it exhibits tolerance. However, clinical and experimental evidence shows that certain diseases exist in which the patient apparently destroys his/her own cells. The reactions could involve Tc cells, B cells orNK cells, and the result of the reaction with antigen may result in a pathological condition arising (autoimmune disease). Autoimmunity is the mirror-image of tolerance and reflects the loss of tolerance to self... 

Endo S, Nishijima M, Nomura H, Takaku A, Okada E. A pathological study of intracranial posterior circulation dissecting aneurysms with subarachnoid hemorrhage report of three autopsied cases and review of the literature. Neurosurgery 1993 33 732-738. 

There is a long-standing hypothesis that the microvasculature plays a pathological role in forms of chronic inflammatory polyarthritis, particularly RA (Rothschild and Masi, 1982). One of the proposed mechanisms of vascular damage in connective tissue disease is the direct action of a cytotoxic serum factor inducing endothelial cell damage. Blake et al. (1985) have su ested that the vascular abnormalities associated with RA may be linked to oxidized lipoproteins because they are cytotoxic to endothelial cells. 

Under normal circumstances the arterial pH is tightly regulated between 7.35 and 7.45. Acidemia is an abnormally low arterial blood pH (less than 7.35) while acidosis is a pathologic process that acidifies body fluids. Similarly, alkalemia is an abnormally high arterial blood pH (less than 7.45) while alkalosis is a pathologic process that alkalinizes body fluids. As such, although a patient can simultaneously have acidosis and alkalosis, the end result will be acidemia or alkalemia. 

Pain can be divided into two broad categories acute and chronic or persistent pain. Acute pain is also referred to as adaptive pain since it serves to protect the individual from further injury or promote healing.17 However, chronic pain has been called maladaptive, a pathologic function of the nervous system or pain as a disease. 

Anovulation also may occur at any time during the reproductive years due to a pathologic cause. The most common causes of non-physiologic ovulatory dysfunction and their prevalence rates11 are ... 

Once a pathologic diagnosis of cancer is made, the patient may be evaluated by a radiation oncologist, a surgical oncologist, and... 

Acidosis A pathologic state that leads to acidemia. 

Acromegaly A pathologic condition characterized by excessive production of growth hormone during adulthood after epiphyseal (long bone) fusions have completed. 

Hypoxia A pathologic condition in which the body (generalized hypoxia) or region of the body (tissue hypoxia) is deprived of adequate oxygen supply (partial arterial oxygen pressure less than 80 mm Hg). Hypoxia in which there is complete deprivation of the oxygen supply is referred to as anoxia. 

Another prominent site of deposition of (5-amyloid fibrils with age and in AD is within the cerebrovasculature in areas of the brain prone to parenchymal amyloid deposition [137-139]. The peptide deposits along the surfaces of the smooth muscle cells of the vascular wall, resulting in the death of those cells and their replacement by amyloid fibrils, weakening the vascular wall. Endothelial cells are also affected [140]. The Dutch mutation in the APP precursor protein Q22E, within the (5-peptide sequence, produces a particularly fibrillogenic and toxic (to smooth muscle cells) peptide associated with primarily vascular deposition of mutant peptide and hemorrhagic vessel disease [137]. Thus, in addition to neuronal cells, the brain vascular smooth muscle cells are a pathologically relevant cell type. While the source of... 

Schmidt The only place that I can imagine that would be happening is in a pathological state in a mammalian organism, where the organism is in an insulin replete state and it hypertrophies its liver in response, where there is more plasticity. 

Ketosis is a pathologic state produced by an excess of ketone bodies in the organism. However, ketosis may be regarded as a lipid metabolism pathology with a certain reserve, since excessive biosynthesis of ketone bodies in the liver is sequent upon an intensive hepatic oxidation not only of fatty acids, but also of keto-genic amino acids. The breakdown of the carbon frameworks of these amino acids leads to the formation of acetyl-CoA and acetoacetyl-CoA, which are used in... 

Affective disorders A group of psychoses characterised by a pathological and long-lasting disturbance of mood or affect. They include the unipolar disorders (e.g., depression and mania), and bipolar disorders (e.g., manic depression). 

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