Evidence circumstantial

This is because on one hand, heav wave is weaker and on the other hand, photoelastic testing method is unfavorable for observing the sound field of axial symmetry. The sound field (see Fig.4) excited by strip ciystal in solid is observed with photoelastic testing method. The wavefront of head wave can be see in Fig.4, which is a circumstantial evidence of wavefront of head wave excited just by point-shape crystal. We can calculate... 

Perhaps the simplest examination done is the physical match. A small fragment of wood, plastic, or other material is recovered and fitted into a large piece found on the suspect or at the scene of the crime (39). Other examinations result ordy in demonstrating class characteristics (40). Such information may be used in a prosecution as circumstantial evidence in a trial. However, it is important that the forensic scientist neither inflate nor minimize (41,42) its importance. 

Inhibition of Nitrosamine Formation. Nitrites can react with secondary amines and A/-substituted amides under the acidic conditions of the stomach to form /V-nitrosamines and A/-nitrosamides. These compounds are collectively called N-nitroso compounds. There is strong circumstantial evidence that in vivo A/-nitroso compounds production contributes to the etiology of cancer of the stomach (135,136), esophagus (136,137), and nasopharynx (136,138). Ascorbic acid consumption is negatively correlated with the incidence of these cancers, due to ascorbic acid inhibition of in vivo A/-nitroso compound formation (139). The concentration of A/-nitroso compounds formed in the stomach depends on the nitrate and nitrite intake. 

The second line of circumstantial evidence quoted in support of this hypothesis is the ready formation of l,2,3,4-tetrahydro-/3-carboline derivatives under pseudo-physiological conditions of temperature, pH, and concentration. Tryptamine and aldehydes, trypt-amine and a-keto acids, and tryptophan and aldehydes condense at room temperature in a Pictet-Spengler type intramolecular Mannich reaction in the pH range 5.2-8.0 (cf. Section III, A, 1, a). It was argued that experiments of this type serve as models for biochemical reactions and may be used in evidence. 

The Diels-Alder intermediate (95) is also rapidly trapped by aromatization in the presence of acids (Scheme 3.64). Thus, the observation hy Buzanovvski < / al.,iK of dramatically lower rates for S polymerizations carried out in the presence of various acid catalysts, is circumstantial evidence for the Mayo mechanism. 

In the case of allyl peroxides (12 X= CH2, A=CH2, BO),1 1 1 intramolecular homolytic substitution on the 0-0 bond gives an epoxy end group as shown in Scheme 6.18 (1,3-Sn/ mechanism). The peroxides 52-59 are thermally stable under the conditions used to determine their chain transfer activity (Table 6.10). The transfer constants are more than two orders of magnitude higher than those for dialkyi peroxides such as di-f-butyl peroxide (Q=0.00023-0.0013) or di-isopropyl peroxide (C =0.0003) which are believed to give chain transfer by direct attack on the 0-0 bond.49 This is circumstantial evidence in favor of the addition-fragmentation mechanism. 

Hi) Poly amines. In many respects the role of poly amines in plant functioning is still mysterious after many years work. They are almost certainly involved in the control of growth and development through their interactions with nucleic acids and membranes (Smith, 1985). There is increasing circumstantial evidence for their involvement, especially of putrescine, in plant responses to a wide range of stresses including pH, Mg deficiency, osmotic shock, cold, SO2 pollution, and cadmium and ammonium toxicity (Smith, 1985). It remains to be determined, however, how, and indeed whether, putrescine accumulation in response to these diverse stresses is beneficial. 

Although the o-hydroxylation hypothesis has been given considerable support, it is clear that nitrosamines with alkyl side chains longer than methyl present additional possibilities for biological activation. It was stated earlier that even the o-hydroxylation hypothesis is based on considerable circumstantial evidence. This means that the other possible pathways are even more speculative, and hence, much more research needs to be carried out before some of the ideas advanced below will gain acceptance, or be put to rest. 

Im summary, it was not possible to achieve all analytical goals in this study of AN/S polymerizations. We were unable to approximate total solids contents directly because of presence of insoluble polymer. Circumstantial evidence sug-... 

For over 35 years, the quinone methide species has been invoked as a reactive intermediate in bioreductive alkylation and in other biological processes.8 29 Generally, there is only circumstantial evidence that the quinone methide species forms in solution. Conceivably, the O-protonated quinone methide (i.e., the hydroquinone carbocation) could be the electrophilic species. If so, bioreductive alkylation may simply be an SN1 reaction. Also, there are questions concerning the mechanism of quinone methide... 

The UV-Vis spectral detection of an intermediate in the catalytic reductive alkylation reaction provides only circumstantial evidence of the quinone methide species. If the bioreductive alkylating agent has a 13C label at the methide center, then a 13C-NMR could provide chemical shift evidence of the methide intermediate. Although this concept is simple, the synthesis of such 13C-labeled materials may not be trivial. We carried out the synthesis of the 13C-labeled prekinamycin shown in Scheme 7.5 and prepared its quinone methide by catalytic reduction in an N2 glove box. An enriched 13C-NMR spectrum of this reaction mixture was obtained within 100 min of the catalytic reduction (the time of the peak intermediate concentration in Fig. 7.2). This spectrum clearly shows the chemical shift associated with the quinone methide along with those of decomposition products (Fig. 7.3). 

A few questions come to mind. What is the structure of the aggregate and why are 2 equiv of each reagent essential Is it due to the acidic proton (N-H) in 41 Before going into the detail of the mechanism, let us assemble more circumstantial evidence on this reaction. 

Thus, three additional pieces of circumstantial evidence are added to the list... 

Zimmerman(24,a6> has provided strong circumstantial evidence that zwitterionic intermediates can be involved in formation of cyclopropyl ketones from dienones. His approach was to generate the dipolar species via ground state chemistry and show that these rearrange to the photoproduct ... 

In addressing the basic question, then, of why more egalitarian societies tended to be healthier than less egalitarian ones, Wilkinson believes that the most plausible explanations focus on the way that the social environment is affected by inequality. He emphasized cases in which unusually healthy and egalitarian societies provide circumstantial evidence that more egalitarian countries were more socially cohesive than less egalitarian ones. Data observed from several sources have strongly confirmed this pattern (Wilkinson, 1996 Kawachi and Kennedy, 1997). 

Jupiter s moon Europa has only been the subject of intense scientific investigation in recent years it is considered to be a member of that small group of heavenly bodies which could perhaps accommodate life (or a precursor of life). About 20 years ago, the Voyager passes afforded sensational pictures of Europa. These showed a network of linear bands, of differing breadths, on a very bright surface. The mean density was calculated as 3,018 35 kg/m3, and the surface temperature measured was 90-95 K. Circumstantial evidence points to either a surface consisting of water ice, or the presence of liquid water or warm ice under the surface. Three models were proposed (Oro et al., 1992) ... 

In conclusion it is the writer s view that there is good circumstantial evidence that the polymerization requires that a complex of the type (VIII) is formed. The concentration of the complex is, however, small, probably less than one percent of the Zr (benzyl) 4 present. This is compensated for by the rapid rate at which it is formed. Further attempts using novel techniques are currently being applied to detect the presence of species of the type (VIII). 

Involvement of direct or indirect excitotoxicity in neurodegenerative disorders such as Huntington s disease, Parkinson s disease, and Alzheimer s disease has long been postulated on the basis of several tines of circumstantial evidence [23]. 

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