Vicious circle

Dielectric Strength. Dielectric failure may be thermal or dismptive. In thermal breakdown, appHed voltage heats the sample and thus lowers its electrical resistance. The lower resistance causes still greater heating and a vicious circle, leading to dielectric failure, occurs. However, if appHed voltage is below a critical value, a stabilized condition may exist where heat iaput rate equals heat loss rate. In dismptive dielectric failure, the sample temperature does not iacrease. This type of failure is usually associated with voids and defects ia the materials. 

Embrittlement embrittlement and for improperly heat treated steel, both of which give intergranular cracks. (Intercrystalline penetration by molten metals is also considered SCC). Other steels in caustic nitrates and some chloride solutions. Brass in aqueous ammonia and sulfur dioxide. physical environments. bases of small corrosion pits, and cracks form with vicious circle of additional corrosion and further crack propagation until failure occurs. Stresses may be dynamic, static, or residual. stress relieve susceptible materials. Consider the new superaustenitic stainless steels. 

For differential equations with periodic coefficients, the theorems are the same but the calculation of the characteristic exponents meets with difficulty. Whereas in the preceding case (constant coefficients), the coefficients of the characteristic equation are known, in the present case the characteristic equation contains the unknown solutions. Thus, one finds oneself in a vicious circle to be able to determine the characteristic exponents, one must know the solutions, and in order to know the latter, one must know first these exponents. The only resolution of this difficulty is to proceed by the method of successive approximations.11... 

Metabolic acidosis can also result when a person is severely burned. Blood plasma leaks from the circulatory system into the injured area, producing edema (swelling) and reducing the blood volume. If the burned area is large, this loss of blood volume may be sufficient to reduce blood flow and oxygen supply to all the body s tissues. Lack of oxygen, in turn, causes the tissues to produce an excessive amount of lactic acid and leads to metabolic acidosis. To minimize the decrease in pH, the injured person breathes harder to eliminate the excess C02. However, if blood volume drops below levels for which the body can compensate, a vicious circle ensues in which blood flow decreases still further, blood pressure falls, C02 excretion diminishes, and acidosis becomes more severe. People in this state are said to be in shock and will die if not treated promptly. 

Fig. 2.2 Simplified scheme of oxidant/antioxidant regulation ofNF-KB activation. Different stimuli, leading to an increase of ROS generation inside the ceU, activate the phosphorylation of IkB inhibitory protein and the subsequent proteolysis. Thioredoxin (Trx) may reduce activated NF-kB proteins facilitating nuclear translocation.Qnce released from IkB, the NF-kB complex translocates into the nucleus and the binding to DNA domain in the promoters and enhancers of genes such as TNF-a, IL-1, proliferation and chemotactic factors, adhesion molecule. Some of these genes, in turn, may further induce NF-kB activation, leading to a vicious circle if the regulatory cellular system escapes from...

Faulty Barrier Function A Possible Vicious Circle Mechanism... 

Fic. 2. Summary of the etiological position and possible vicious circle mechanism. 

The generation of acetaldehyde (AA) as a decomposition product in PET processing plays an important role in bottle manufacturing. This depends on the vicious circle of the polymer stability, the AA content of the chips prior to processing, and the processing conditions. The basis of stability is a qualified polymer produced under appropriate conditions. This argument also includes the SSP process which can drastically reduce the AA content of the chips, as shown in Figure 13.21. 

The healthy small intestine contains only a small bacterial population, unlike the colon. However, an acute infection of the mucosa by a virus, bacterium or other parasite can reduce its motility, allowing a huge proliferation of the resident bacteria. Absorption of both macro- and micronutrients is impaired, resulting in the disorder known as sprue. Folic acid is particularly poorly absorbed, causing reduced rates of repair of mucosal cells. Hence, the damage persists and worsens to create a vicious circle. Treatment involves administration of an antibiotic to kill the bacteria and folic acid to allow damaged tissue to recover. The clinical presentation includes bulky stools, steatorrhoea (fatty faeces) and weight loss. 

The amonnt of protein synthesised and then released in (iv) and (v) is abont 70 g each day. Even under conditions of starvation or malnutrition, proliferation and differentiation of stem cells located in the crypts of the villi are important to provide the cells necessary for replenishment of those lost from the villi. New cells move up the villus to replace those lost at the top. Under these conditions, amino acids are not available from the intestine and have to be taken up from the blood across the basolateral membrane. A low level of amino acids in the blood, due to chronic malnutrition, will prevent or reduce the rate of proliferation of these cells, so that digestion of even the small amount of food ingested during malnutrition, or refeeding after starvation, is difficult. A vicious circle thus results from protein-deficient diets which increase the risk of development of protein-energy-malnutrition. This is especially severe in children but may also contribute to the clinical problems that occur in the elderly whose diets are of low quality. 

Senile dementia can result in an even lower intake of food with further diminution of vitamin levels, so that a vicious circle can develop. 

Ui) Bacterial translocation from colon due to hypoxic damage Reperfusion damage to the colonocytes can impair the physical barrier between the contents of the colon and the blood. This leads to translocation of bacteria (some of which are pathogens (e.g. E. coli)), or lipopoly-saccharide (endotoxin) into the peritoneal cavity and evenmaUy into the bloodstream. Activation of the gut-associated immune system results in local inflammation which can also damage the barrier and hence increase bacterial translocation. This sets up a vicious circle, with the development of peritonitis and possible systemic sepsis (Figure 18.6). 

In most, if not all, chronic inflammatory diseases endothelial cells are prominently involved in the disease process. This is demonstrated by an increased expression of adhesion molecules and production of cytokines, and their pro-angiogenic behaviour. This leads to continuous recruitment of leucocytes into the inflamed area, without (detectable) antigen present in the affected tissue, resulting in a vicious circle of tissue damage and leucocyte recruitment. Targeting inhibitory agents (in)to the endothelial cell may interrupt in this process by controlling the activation status of this cell type. 

Finally, the most efficient columns permit the use of lai er particles to achieve the required performance and therefore the necessary pressure drop is smaller. In our case the maximum particle diameter is Vm for the best and only 3 /iih for the worst column. In practice it iimuch easier to pack an efficient column with 9 /jitn rather than with 3-/x particles, and this is a good example of a vicious circle encountered witl such problems. 

The second problem is hidden in the word different . In conjunction with the first problem, this constitutes a vicious circle. For specification, only those properties of a ligand are relevant that are not altered by permutation but these can only be assessed for the isolated ligand, i.e., when the ligand is considered to be separate from the stereogenic center. 

The only way open to you to break out of this kind of vicious circle is to behave as if you trusted the other person. To do this you have to trust him or her. Which means replacing a belief of mistrust by one of trust. Put another way, it means letting go of your old belief and probably too the feelings that attached to it. This is not always easy. 

The managanent of chemical eye bums is not the sole concern of the ophthalmologist. It takes often several hours between the bum and the visit to the ophthalmologist. During this time, many tfeatments have been administered, or most often, not administered because they have not been approved by the specialist. Therefore, at the time of the visit to the ophthalmologist, the prognosis is already settled. Here, we have a vicious circle the most common vision ophthalmologists have of chemical... 

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