Working hypotheses

The working hypothesis is that, by some means, interaction of an allosteric enzyme with effectors alters the distribution of conformational possibilities or subunit interactions available to the enzyme. That is, the regulatory effects exerted on the enzyme s activity are achieved by conformational changes occurring in the protein when effector metabolites bind. 

As noted in the previous review (99H1157), we proposed a working hypothesis that 1-hydroxyindoles are classified into two groups from the point of reactivity characteristics toward 85% HCOOH (Scheme 34). Thus, type 1 compounds 227... 

The useful corrosion resistance of a stainless steel is due almost entirely to the fact that it exhibits passivity in a wide range of environments. The nature of passivity has been discussed extensively in Sections 1.4 and 1.5 and so will not be considered in detail here. The working hypothesis adopted by many concerned with stainless steel is that the passive film is essentially an oxide, and this has proved a reasonable assumption for practical purposes. 

As far as investigated77, most reactions of the allyllithium-sparteine complexes with electrophiles proceed antarafacially, either as SE2 or anti-SE2 reactions. As a working hypothesis it is assumed that the bulky ligand obliterates the Lewis acid properties of the lithium cation. 

In spite of the fact that the general statement of this principle has been shown to be false from all standpoints, it must be admitted that its enunciation was quite in harmony with the spirit of the times the great physicists Lord Kelvin (1851) and Helmholtz (1847) had previously formulated an identical principle in connection with galvanic cells. Thomsen and Berthelot went wrong, not in tlieir enunciation of the so-called theorem as a working hypothesis, but rather in their... 

To gain an insight into the likely hydrolytic behavior of sulfated simple sugars and polysaccharides, Brimacombe, Foster, Hancock, Overend, and Stacey carried out a rigorous set of experiments with the cyclic sulfates of cyclohexane cis-and trims-1,2-diol as model compounds. The results were interpreted on the reasonable assumption that, in all cases, the cyclic sulfates initially afford a diol monosulfate. Examples of both S-0 and C-0 bond cleavage were encountered. A qualitative reaction mechanism was proposed for use as a working hypothesis for the hydrolysis of sugar sulfates. 

The function of a sensory system is to select suitable modalities from the multitude presented by the environment, and translate them into corresponding modalities of sensory information that are then projected and processed into the various parts and finally submitted to the central processing-unit, the brain. A working hypothesis of the mechanism by which the taste system senses chemical compounds is that macromolecules that are... 

Based on the working hypothesis described above, the author focuses on the chemistry of cyclic porphyrin oligomers (CPOs). As described in the next section, porphyrin is a multi-functional compound and the nano-sized closed space created by these molecules should therefore be of interest to chemists. 

Although there is no evidence that the DA afferents to DLPFC are damaged in schizophrenics, if the cortical pathology does reduce the ability of DA to function there, this would be equivalent to deafferentation and, as in the experimental studies, lead to increased subcortical mesolimbic activity and positive symptoms (Fig. 17.3). Unfortunately there is no good evidence that the nucleus accumbens is more active in schizophrenics or is even the origin of positive symptoms (but see Animal models ). Nevertheless it is a useful working hypothesis. 

All of these results support the o-hydroxylation hypothesis, but they do not prove it. No o-hydroxy nitrosamine or a derivative of one has ever been isolated as a metabolite of any nitrosamine. Nevertheless, a-hydroxylation is an attractive working hypothesis and it seems to account for... 

The method for approximating an RDM in terms of the lower order ones is based on equation (49). The working hypothesis which has been put forward [46] is ... 

A current working hypothesis is that F. and chemoinvestigative behaviour are closely linked, but that it is not restricted to urinalysis by the male. Other signalling functions are indicated by the behaviour of captive and feral groups. Flehmen s role in female female interactions is clearly of equal value since it is highly correlated with rank in the Sable antelope (Hippotragus niger). Dominant females not only perform... 

In this study we use electron microscopy (EM) to study xanthan strandedness and topology both in the ordered and disordered conformation. Correlation of data obtained from electron micrographs to physical properties of dilute aqueous solution on the same sample will be used to provide a working hypothesis of the solution configuration of xanthan. Electron micrographs obtained from xanthan of different origins will be compared to assess similarities and differences in secondary structure at the level of resolution in the used EM technique. 

We have drawn the following tentative conclusions as a working hypothesis for future studies, (i) PGD2 and PGE2 are endogenous sleep and wake substances,... 

The standard of testability (vulnerability to negation in the framework of a working hypothesis in the hypothetico-deductive mode or of simultaneous adjustment in the framework of Bayesian modeling) is probably the toughest standard demanded in science. Ideas as old as the monad are not necessarily tested and validated by repeated corroboration. Indeed, they may be untested and powered by inertia. Ideas which are testable are those for which there are alternatives otherwise ideas are either unnecessary or untestable. Since Dennett has already asserted that reductionism permits no alternative, monophyly as such would have to be untestable, but, before condemning it to the rank of scientific dogma, let me cite two cases in which monophyly was tested as the alternative to a different (polyphylic) hypothesis. 

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