Primary event

Wang Q, Schoenlein R W, Peteanu L A, Mathies R A and Shank C V 1994 Vibrationally coherent photochemistry in the femtosecond primary event of vision Science 266 422... 

The first study in which a full CASSCE treatment was used for the non-adiabatic dynamics of a polyatomic system was a study on a model of the retinal chromophore [86]. The cis-trans photoisomerization of retinal is the primary event in vision, but despite much study the mechanism for this process is still unclear. The minimal model for retinal is l-cis-CjH NHj, which had been studied in an earlier quantum chemisti7 study [230]. There, it had been established that a conical intersection exists between the Si and So states with the cis-trans defining torsion angle at approximately a = 80° (cis is at 0°). Two... 

The mechanism of action of quats has been widely studied. It is generally agreed that their iateraction with the bacterial cell membrane is the primary event resulting ia antimicrobial activity (16,17). 

The two main termination steps for neutral solutions are HO + HO — H2O2 + 2 O3 and HO + HO3 — H2O2 + O3 + O2. An alternative mechanism has been proposed that does not involve HO and HO but has a different initiation step (26). Three ozone molecules are destroyed for each primary event. In the presence of excess HO radical scavengers, ie, bicarbonate, the pseudo-first-order rate constant at 20°C for the initiation step is 175 X. This yields an ozone half-hfe of 66 min at pH 8. In distilled water = 50 mmol/L), the half-hfe is significantly lower, ie, 7 min. 

Under the primary event symbols, the circle represents a component failure for which a description and failure-on-demand or failure frequency data is provided. 

WAMCUT/ 1500 primary events Bottom up Based on both cutset Not option caii generate <... 

Standard and ADL Usage Intermediate level event caused by more primary events dei eloped below... 

Situnayake et al., 1991). No correlation between disease activity and serum vitamin E concentrations was found, but it was su ested that such patients might suffer a reduced antioxidant capacity. However, it is conceivable that a decreased serum antioxidant status is a primary event in the evolution of RA. Recent studies (Heliovaara etal., 1994) have demonstrated that lowered levels of vitamin E, /3-carotene and selenium (required for glutathione peroxidase) together may be a risk fector for subsequent development of RA. 

Further research is required to establish whether free-radical-induced damage is a primary event in diabetes. Tissue damage, which is associated with inactivation of antioxidants and release of metal ions that are potent catalysts of free radical reactions, can lead to lipid peroxidation. This raises the possibility that the diabetic process itself or other frctors may increase free-radical activity following direct tissue damage. 

In addition to excess sodium intake, abnormal renal sodium retention may be the primary event in the development of hypertension, and it includes abnormalities in the pressure-natriuresis mechanism. In hypertensive individuals, this theory proposes a shift in the control mechanism preventing the normalization of blood pressure. The mechanisms behind the resetting of the pressure-natriuresis curve may include afferent arteriolar vasoconstriction, decreased glomerular ultrafiltration, or an increase in tubular sodium reabsorption.4 Other theories supporting abnormal renal sodium retention suggest a congenital reduction in the number of nephrons, enhanced renin secretion from nephrons that are ischemic, or an acquired compensatory mechanism for renal sodium retention.9... 

The primary event in the molecular pathogenesis of SCD involves polymerization of deoxygenated HbS. Since RBCs are packaged with such a high concentration of hemoglobin (32-34 g/dL, 320 to 340 g/L or 19.9-21 mmol/L), it is important... 

Additional insight is possible from Fig. 38b. Here we see that the magnitude of the explained variance accounted for by the second PC has noticeably increased after minute 70. This is consistent because, from process knowledge, it is known that removal of water is the primary event in the first part of the batch cycle, while polymerization dominates in the later part, explaining why the variance profile changes around the 70-minute point. 

The primary event which takes place when high energy radiation, such as gamma radiation, interacts with a polymer molecule involves the ejection of an electron, with formation of the polymer cation radical, as shown in Equation (1) ... 

These primary elementary reactions are followed by reaction of intermediates with charge carriers, as well as other solution reactions like hydrolysis, and so the system is, early on, crowded with many species. The following discussion is limited to the analysis of primary events. 

FUNCTION RUBISCO CATALYSES TWO REACTIONS THE CARBOXYLATION OF D-RIBULOSE 1,5-BISPHOSPHATE, THE PRIMARY EVENT IN PHOTOSYNTHETIC CARBON DIOXIDE FIXATION, AS WELL AS THE OXIDATIVE FRAGMENTATION OF THE PENTOSE SUBSTRATE IN THE PHOTORESPIRATION PROCESS. BOTH REACTIONS OCCUR SIMULTANEOUSLY AND IN COMPETITION AT THE SAME ACTIVE SITE. 

A recent report suggests that inhibition of PC synthesis constitutes one of the primary events by which C2-ceramide triggers apoptosis (Ramos et al, 2000). Treatment of cerebral granule neurons with C2-ceramide resulted in a rapid (within 1 hour) reduction in PC biosynthesis, whereas only 6 h after exposure to the agonists the first significant drop in cell viability was observed. The authors further showed that addition of exogenous PC resulted in a dose-dependent full prevention of neuronal death. This was specific for PC, because addition of other glycerohpids Uke, PE, PS, phosphatidylinositol and phosphatidic acid had no effect on C2-ceramide-induced apoptosis. 

All analytical techniques in the TEM are based on the inelastic scattering of the fast beam electrons by the electrons of the atoms in the material investigated. The primary event in each case is the transfer of energy and momentum from the fast electron to a sample atom, thereby exciting the... 

An example that alterations in the ubiquitin-proteasome system may be a primary event in AD, after ABP-induced toxicity or accumulation, was provided by Konishi et al. (273), who found that frameshift ubiquitin-B was present in subjects with AD pathology prior to development of dementia, probably accumulating in the initial steps of AD pathogenesis, whereas complement proteins were detected in AD patients but not in subjects with AD pathology and no symptoms of dementia, indicating the involvement of complement proteins in the later stage of dementia (273). 

Domino effects—The triggering of secondary events, such as toxic releases, by a primary event, such as an explosion, such that the result is an increase in consequences or area of an effect zone. Generally only considered when a significant escalation of the original incident results sometimes known as a knock on event. 

We examine here possible structural effects that may result from or accompany the generation of the primary photoproducts, and speculate about the consequences of concomitant changes in distances,conformations, relative orientations and charges on the electronic profiles of and interactions between the BChls, BPheos and their radicals. Because the primary events in green plant photosynthesis also involve a series of chlorophyll donors and acceptors ( ), similar trends should therefore prevail for chlorophyll radicals as well. Furthermore, radicals of porphyrins and hydroporphyrins (saturated porphyrins such as chlorins and isobacteriochlorins) have been... 

Topical drug preparations are applied for days or even weeks, cosmetics for a lifetime and skin contact is probably the most common form of exposure to industrial chemicals. Therefore, a knowledge of the cutaneous toxicity is important for an overall hazard assessment. Cutaneous toxicity or localised skin injury can be considered as a primary event, because the compound could be irritant or corrosive, or as a secondary immunologically mediated event causing a delayed hypersensitivity response. 

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