Hypothesis tentative

Paper nine is another one that appeared in American Scientist. In it I took a philosophical look at two important ideas that contributed to the evolution of the periodic system. These two ideas are Prout s hypothesis and the notion of triads, which was the subject of paper eight. Both hypotheses are interesting because they were extremely productive even though they both turned out to be refuted some time later. The fact that this should happen lends some support to the views of Karl Popper who always claimed that refutability was the all important aspect of good hypotheses and theories and not whether they turn out to be correct or not.23 For Popper, all that we really have is tentative theories and not theories that last forever. 

These two redox-linked protons were tentatively attributed to the N -protons of the cluster-ligating histidine residues (130, 131, 137). Although this attribution appears likely in the light of the structure, so far no experimental evidence substantiating this hypothesis is available. 

However a new chemical discovery arises, an essential component of science is to explain that discovery on the basis of general principles. When a new general principle is posed, it is termed a hypothesis. A hypothesis is tentative until it can be confirmed in two ways. First, additional observations must be consistent with the hypothesis second, the hypothesis must predict new results that can be confirmed by experiments. If a hypothesis meets these tests, it is promoted to the status of a theory. A theory is a unifying principle that explains a collection of facts. 

C pose a tentative hypothesis explaining what was observed... 

Experiments with rats given oral doses of tritiated food-grade mineral oil provide supporting evidence that the absorption of hydrocarbons in mineral oils is limited. Five hours after dosing with 0.66 mL/kg of tritiated mineral oil ("liquid petrolatum U.S.P."), -75% of the administered radioactivity remained in the alimentary tract, and only 3% of the administered radioactivity was accounted for by radioactivity in other parts of the rat carcass (Ebert et al. 1966). About 80% of the administered radioactivity was recovered in feces during the first 2 days after treatment, and over 90% of the radioactivity in the feces was in the form of mineral oil. These data are consistent with the hypothesis that ingested mineral oil was poorly absorbed. Neither biliary excretion nor enterohepatic circulation of mineral oils was measured in this study, and thus, any quantitative estimates of the extent of absorption based on these data should be viewed as tentative. 

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

One sees that both proponents of the idea that substitutions at sulfinyl sulfur involve a concerted mechanism (154a) and those who favor a stepwise process (154b) where an intermediate is present on the reaction coordinate can find experimental results to support their point of view. In Section 9 in discussing substitutions at sulfonyl sulfur we will present a tentative hypothesis which we believe can rationalize the seemingly conflicting experimental evidence. 

Just as was true for substitutions at S=0, and as will also be true for substitutions at S02 (Section 9), the experimental results do not clearly resolve the question of whether substitutions at sulfenyl sulfur are best represented as concerted (173a) or stepwise (173b). Proponents of either pathway can find certain results that seem to support their viewpoint and others that are difficult to reconcile with it. In Section 9, in connection with discussion of the same problem vis-a-vis substitutions at sulfonyl sulfur, we shall present a tentative hypothesis that we think may provide a means of reconciling the seemingly contradictory experimental results within a single conceptual framework and that is applicable to substitutions at sulfur in all of the different oxidation states. 

Sohowdo we know when we know something The building of knowledge usually begins with an observation or an idea leading to a hypothesis a tentative statement of belief. To be any good, a hypothesis must fulfill certain criteria it must be testable,... 

An empirical structure-property relation is based on observations in a set of fragmentary and incomplete data, instead of being based on a well-established theory of wide applicability and tested extensively. It is a tentative hypothesis designed to explain... 

Hypothesis a tentative statement used to explain some aspect of nature and tested through an experiment latrochemical medical school of thought that attributed disease to chemical imbalances in the body... 

On the basis of the above data, a tentative hypothesis has been advanced for the observed asymmetric induction. The carbonyl oxygen of benzaldehyde forms a H-bond with the piperazine ring NH of the histidine, the imidazole is protonated by the HCN, and the resulting cyanide ion attacks the si face of the activated carbonyl group since the re face is blocked by the phenyl ring of the phenylalanine, as seen in the Fig. 1. 

On the other hand, no differences were found in growth or mortality of tent caterpillars fed leaves from unattacked willows compared to those fed leaves from willows attacked by tent caterpillars (Figure IB). Reload of the attacked trees with additional tent caterpillars coincided with a rapid decrease in biomass and an increased mortality of Insects fed leaves from both attacked and unattacked control trees. This could have been by chance, but it suggested the possibility that both attacked and control trees exhibited a rapid decrease in food quality in response to the addition of more insects to the attacked trees. If so, this suggested that unattacked willows were sensitive to signals from nearby attacked willows or the attacking Insects. An experiment to test this hypothesis produced positive results (Figure 2). 

As I write, this important frontier is just beginning to be explored and what I say about it should be taken as tentative hypothesizing, but I want to make the central hypothesis crystal clear artificial alteration of the neuromodulatory systems that control consciousness can produce potent changes, some desirable and some decidedly undesirable. This means that a scrupulous and conservative cost-benefit analysis needs to be undertaken during the next few years, when we can expect the use of these agents to peak and their long-term effects to become more obvious. 

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