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931.
Peter R. Anstey 《Studies in history and philosophy of science》2004,35(2):247-269
This paper analyses the different ways in which Isaac Newton employed queries in his writings on natural philosophy. It is argued that queries were used in three different ways by Newton and that each of these uses is best understood against the background of the role that queries played in the Baconian method that was adopted by the leading experimenters of the early Royal Society. After a discussion of the role of queries in Francis Bacon’s natural historical method, Newton’s queries in his Trinity Notebook are shown to reveal the influence of his early reading in the new experimental philosophy. Then after a discussion of Robert Hooke’s view of the role of queries, the paper turns to an assessment of Newton’s correspondence and Opticks. It is argued that the queries in his correspondence with Oldenburg on his early optical experiments are closely tied to an experimental program, whereas the queries in the Opticks are more discursive and speculative, but that each of these uses of queries represents a significant Baconian legacy in his natural philosophical methodology. 相似文献
932.
933.
Aggregation of equivalence relations 总被引:1,自引:1,他引:0
Each ofn attributes partitions a set of items into equivalence classes. Aconsistent aggregator of then partitions is defined as an aggregate partition that satisfies an independence condition and a unanimity condition. It is shown that the class of consistent aggregators is precisely the class ofconjunctive aggregators. That is, for each consistent aggregator there is a nonempty subsetN of the attributes such that two items are equivalent in the aggregate partition if and only if they are equivalent with respect to each attribute inN. 相似文献
934.
Peter Fishburn 《Systemic Practice and Action Research》1990,3(2):183-194
My mother wanted me to become a wealthy corporate executive. My father didn't care what I became as long as I didn't do too well at it. Russ Ackoff wanted me to become whatever I wanted, and the better I could do at it, the happier he would be. I chose the last of these and have enjoyed every minute. Thanks, Russ. 相似文献
935.
In this paper we make an empirical investigation of the relationship between the consistency, coherence and validity of probability judgements in a real-world forecasting context. Our results indicate that these measures of the adequacy of an individual's probability assessments are not closely related as we anticipated. Twenty-nine of our thirty-six subjects were better calibrated in point probabilities than in odds and our subjects were, in general more coherent using point probabilities than odds forecasts. Contrary to our expectations we found very little difference in forecasting response and performance between simple and compound holistic forecasts. This result is evidence against the ‘divide-and-conquer’ rationale underlying most applications of normative decision theory. In addition, our recompositions of marginal and conditional assessments into compound forecasts were no better calibrated or resolved than their holistic counterparts. These findings convey two implications for forecasting. First, untrained judgemental forecasters should use point probabilities in preference to odds. Second, judgemental forecasts of complex compound probabilities may be as well assessed holistically as they are using methods of decomposition and recomposition. In addition, our study provides a paradigm for further studies of the relationship between consistency, coherence and validity in judgemental probability forecasting. 相似文献
936.
This paper reviews the relations between the methods of seasonal adjustment used by official statistical agencies and the ‘model-based’ methods that postulate explicit stochastic models for the unobserved components of a time series and apply optimal signal extraction theory to obtain a seasonally adjusted series. The Kalman filter implementation of the model-based methods is described and some recent results on its properties are reviewed. The model-based methods employ homogeneous or time-invariant models that assume in particular that the autocovariance structure does not vary with the season. Relaxing this leads to the class of models known as periodic models, and an example of a seasonally heterosceclastic unobserved-components ARIMA (SHUCARIMA) model is presented. The calculation of the standard error of a seasonally adjusted series via the Kalman filter is extended to this periodic model and illustrated for a monthly rainfall series. 相似文献
937.
Peter L. Jørgensen 《Cellular and molecular life sciences : CMLS》1971,27(5):527-528
Zusammenfassung Nach Uninephrektomie und bilateraler Adrenalektomie entsteht eine Dissoziation zwischen der Nierenvergrösserung und der (Na++K+)-ATPase Aktivität. Es besteht wahrscheinlich kein Zusammenhang zwischen der Nierenvergrösserung und der Induktion von (Na++K+)-ATPase. Auch in der vergrösserten Niere sind die Nebennierenhormone notwendig, um die (Na++K+)-ATPase zu erhalten.
The work was supported by a grant from P. Carl Petersen's Fund. Mrs.Birthe Bagge Hansen provided excellent technical assistance. 相似文献
The work was supported by a grant from P. Carl Petersen's Fund. Mrs.Birthe Bagge Hansen provided excellent technical assistance. 相似文献
938.
939.
Strong present-day aerosol cooling implies a hot future 总被引:1,自引:0,他引:1
Atmospheric aerosols counteract the warming effects of anthropogenic greenhouse gases by an uncertain, but potentially large, amount. This in turn leads to large uncertainties in the sensitivity of climate to human perturbations, and therefore also in carbon cycle feedbacks and projections of climate change. In the future, aerosol cooling is expected to decline relative to greenhouse gas forcing, because of the aerosols' much shorter lifetime and the pursuit of a cleaner atmosphere. Strong aerosol cooling in the past and present would then imply that future global warming may proceed at or even above the upper extreme of the range projected by the Intergovernmental Panel on Climate Change. 相似文献
940.
Understanding the molecular genetic basis of adaptations provides incomparable insight into the genetic mechanisms by which evolutionary diversification takes place. Whether the evolution of common traits in different lineages proceeds by similar or unique mutations, and the degree to which phenotypic evolution is controlled by changes in gene regulation as opposed to gene function, are fundamental questions in evolutionary biology that require such an understanding of genetic mechanisms. Here we identify novel changes in the molecular structure of a sodium channel expressed in snake skeletal muscle, tsNa(V)1.4, that are responsible for differences in tetrodotoxin (TTX) resistance among garter snake populations coevolving with toxic newts. By the functional expression of tsNa(V)1.4, we show how differences in the amino-acid sequence of the channel affect TTX binding and impart different levels of resistance in four snake populations. These results indicate that the evolution of a physiological trait has occurred through a series of unique functional changes in a gene that is otherwise highly conserved among vertebrates. 相似文献