Lifespan

Deriva.tives, The most important derivatives of 1,2,3,4-benzenetetrol are the ubiquiaones, eg, coenzyme Q, which are dimethoxytoluquiaones with polyisoprenoid side chains (61). They occur ia plants and animals. Mice with hereditary muscular dystrophy have a deficiency of coenzyme Q ia their heart and hind leg muscles. Therapeutic adrninistration of coenzyme Q /7339-63-5] produces physical improvement and a significantly prolonged lifespan (212). Coenzyme Q also has been used to treat deafness when adrninistered either orally or parenteraHy (213). 

Short-term repeated exposures involve consecutive daily exposures to the test chemical which are continued over a period of a few days to a few weeks but usually not more than 5% of the lifespan of the animal. These test conditions are sometimes referred to as subacute, but this is a misleading term which should be avoided in order to prevent confusion between single and repetitive exposure toxicity. 

Subchronic exposures involve consecutive daily exposures to the test material for a period amounting to usually no more than 10—15% of the lifespan of the test species. 

Corrected for six-month lifespan of lambs, which account for 50% of June census sheep numbers. 

For a power station, assuming a corrosion factor for a lifespan ot 40 years as 0.12 mm/year then... 

Ancient iron structures sometimes show no sign of corrosion or at most, very little. The clean atmosphere of past centuries may be responsible in that it allowed a very thin adherent layer of oxide to develop on the surface [22], This layer very often protects against even today s increasingly aggressive industrial pollutants Very often the conditions of the initial corrosion are the ones that determine the lifespan of metals [23], A well-known example is the sacred pillar of Kutub in Delhi, which was hand forged from large iron blooms in 410 a.d. In the pure dry air, the pillar remains free of rust traces but shows pitting corrosion of the iron... 

In eontrast with the predietive strategy, a preventive strategy aims toward maximum safety against unexpeeted failures. The basie eoneept is to prediet the average lifespan of a part and then replaee it before the end of that lifespan. Annual eost is therefore higher (8%-10% of the prime equipment priee) beeause it is neeessary to purehase and warehouse more spare parts. 

Stable intermediates are those where concentration and lifespan are comparable to those of stable reactants and products. An example is the reaction between methane and oxygen in the gas phase at 700 K and 1 atmosphere. The overall reaction is ... 

Generally, active centers are highly reactive intermediates present in very small concentrations with short lifespans. For example, in the case of... 

The life span of a batteiy is also dependent on the power needs of a product. Some batteries produce a lot of power for a relatively short time before fully discharging, while others are designed to provide less peak power but more sustained power for a very low drain rate. Other important variables aftccting batteiy lifespan are the design and efficiency of the device being used and the conditions of use. In particular, exposing a batteiy to excessive heat can dramatically curtail the length of a battery s life. 

LDTs and SUVs exhibit much higher emissions levels than do automobiles (roughly 30 percent more lie and CO, and 85 percent more NO. per mile traveled). Light-duty trucks also have a significantly longer lifespan in the fleet than do automobiles, compounding the emissions impact over time. 

The durability of a building (i.e. its life expectancy and its resistance to deterioration) is determined by deliberate design decisions relating to stmcture and choice of materials as much as to the natural or precipitate process of ageing. Within certain limits, the design of an industrial building can and should take into account the predicted use or lifespan of the process or method of operation which it is to accommodate. To aim at durability beyond that has ascertainable cost implications. These may be acceptable if the building is to serve future known or even unpredictable purposes. 

Selective serotonine reuptake inhibitor (SSRI) is an abbreviation for the class of antidepressants known as the Selective Serotonin Reuptake Inhibitors. Examples of SSRIs include fluoxetine, paroxetine, citalopram, and sertraline. These drugs selectively inhibit the serotonin transporter thus prolonging the synaptic lifespan of the neurotransmitter serotonin. 

SWS/SWA, in particular, may play an important role in somatic and cognitive restoration, including the consolidation of certain forms of procedural and declarative memory. A substantial diminution in the amount of SWS/SWA occurs across the human lifespan. This decline is beginning already in adolescence and middle-aged adults have only 25% of the SWS observed in young adults, whereas the elderly have almost none. While the clinical importance of these phenomena is unknown, it is reasonable to speculate that they may be related to the increase of sleep complaints associated with aging. 

These problems are more acute in the power industry, where intermittently operated, peaking steam generators produce and collect significantly more iron oxides than base load boilers. Frequent startups of power boilers are very detrimental to their lifespan. 

The mentoring pairs met up roughly every other month and the lifespan of the relationship was determined by the participant s feelings about the value that they were gaining from it. The mentor s performance was regularly reviewed by the executive team, and mentees were regularly surveyed to understand the impact of the program on their needs. 

In spite of the above-mentioned similarities between basophils and mast cells, they differ in many other aspects [1,2]. Basophils complete their differentiation within the bone marrow, and mature basophils circulate in the peripheral blood and do not usually infiltrate into peripheral tissues unless inflammation takes place. Mast cells originate from hematopoietic cells in the bone marrow as do basophils, but they mature in peripheral tissues after their bone marrow-derived precursors enter the circulation and migrate into peripheral tissues. Mature mast cells reside in peripheral tissues and do not usually circulate in the peripheral blood. The lifespan of basophils is very short (several days), in contrast to that of mast cells (weeks to months). Basophils do not proliferate once they terminally differentiate whereas mature mast cells keep potential to expand in response to various stimuli. These differences between basophils and mast cells, including distinct anatomical localization, suggest their differential roles in vivo. 

CHRONIC TOXICITY Adverse health effects in a living organism resulting from repeated daily exposures to a chemical for a significant part of the organism s lifespan. 

Since the endogenous levels of inducible transcription factors like NF-kB and NFAT (Duh et al. 1989 Kinoshita et al. 1997) in these cells have been reported to be very low, HIV-1 promoter activation is inefficient resulting in non-expression of viral gene products (Figs. 5.1 and 5.2). Therefore, these cells can escape immune surveillance and act as passive carriers of HIV-1 for their natural lifespan. 

The ideal of any vaccine is to provide life-long protection to the individual against disease. Immunological memory (Chapter 14) depends upon the survival of cloned populations of small B and T lymphocytes (memory cells). These small lymphocytes have a lifespan in the body of ca. 15-20 years. Thus, if the immune system is not boosted, either by natural exposure to the organism or by re-immunization, then immunity gained in childhood will be attenuated or lost completely by the age of 30. Those vaccines which provide only poor protection against disease have proportionately reduced time-spans of effectiveness. Yellow fever vaccination, which is highly effective, must therefore be repeated at 10-year intervals, whilst typhoid vaccines are only effective for 1-3 years. Whether or not immunization in childhood is boosted at adolescence or in adult life depends on the relative risks associated with the infection as a function of age. 

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