239 research outputs found

    Born's rule from measurements of classical signals by threshold detectors which are properly calibrated

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    The very old problem of the statistical content of quantum mechanics (QM) is studied in a novel framework. The Born's rule (one of the basic postulates of QM) is derived from theory of classical random signals. We present a measurement scheme which transforms continuous signals into discrete clicks and reproduces the Born's rule. This is the sheme of threshold type detection. Calibration of detectors plays a crucial role.Comment: The problem of double clicks is resolved; hence, one can proceed in purely wave framework, i.e., the wave-partcile duality has been resolved in favor of the wave picture of prequantum realit

    Semiparametric Multivariate Accelerated Failure Time Model with Generalized Estimating Equations

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    The semiparametric accelerated failure time model is not as widely used as the Cox relative risk model mainly due to computational difficulties. Recent developments in least squares estimation and induced smoothing estimating equations provide promising tools to make the accelerate failure time models more attractive in practice. For semiparametric multivariate accelerated failure time models, we propose a generalized estimating equation approach to account for the multivariate dependence through working correlation structures. The marginal error distributions can be either identical as in sequential event settings or different as in parallel event settings. Some regression coefficients can be shared across margins as needed. The initial estimator is a rank-based estimator with Gehan's weight, but obtained from an induced smoothing approach with computation ease. The resulting estimator is consistent and asymptotically normal, with a variance estimated through a multiplier resampling method. In a simulation study, our estimator was up to three times as efficient as the initial estimator, especially with stronger multivariate dependence and heavier censoring percentage. Two real examples demonstrate the utility of the proposed method

    Numerical Comparison of Cusum and Shiryaev-Roberts Procedures for Detecting Changes in Distributions

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    The CUSUM procedure is known to be optimal for detecting a change in distribution under a minimax scenario, whereas the Shiryaev-Roberts procedure is optimal for detecting a change that occurs at a distant time horizon. As a simpler alternative to the conventional Monte Carlo approach, we propose a numerical method for the systematic comparison of the two detection schemes in both settings, i.e., minimax and for detecting changes that occur in the distant future. Our goal is accomplished by deriving a set of exact integral equations for the performance metrics, which are then solved numerically. We present detailed numerical results for the problem of detecting a change in the mean of a Gaussian sequence, which show that the difference between the two procedures is significant only when detecting small changes.Comment: 21 pages, 8 figures, to appear in Communications in Statistics - Theory and Method

    Short-Term Exercise Training Does Not Stimulate Skeletal Muscle ATP Synthesis in Relatives of Humans With Type 2 Diabetes

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    OBJECTIVE-We tested the hypothesis that short-term exercise training improves hereditary insulin resistance by stimulating ATP synthesis and investigated associations With gene polymorphisms. RESEARCH DESIGN AND METHODS-We studied 24 nono-bese first-degree relatives of type 2 diabetic patients and 12 control subjects at rest, and 48 h after three bouts of exercise. In addition to measurements of oxygen uptake and insulin sensitivity (oral glucose tolerance test), ectopic lipids and mitochondrial ATP synthesis were assessed using H-1 and P-31 magnetic resonance spectroscopy, respectively. They were genotyped for polymorphisms in genes regulating mitochondrial function, PPARGC1A (rs8192678) and NDUFB6 (rs540467). RESULTS-Relatives had slightly lower (P = 0.012) insulin sensitivity than control subjects. In control subjects, ATP synthase flux rose by 18% (P = 0.0001), being 23% higher (P = 0.002) than that in relatives after exercise training. Relatives responding to exercise training with increased ATP synthesis (+19%, P = 0.009) showed improved insulin sensitivity (P = 0.009) compared with those whose insulin sensitivity did not improve. A polymorphism in the NDUFB6 gene from respiratory chain complex I related to ATP synthesis (P = 0.02) and insulin Sensitivity response to exercise training (P = 0.05). ATP synthase flux correlated with O-2 uptake and insulin sensitivity. CONCLUSIONS-The ability of short-term exercise to stimulate ATP production distinguished individuals with improved insulin sensitivity from those whose insulin sensitivity did not improve. lit addition, the NDUFB6 gene polymorphism appeared to modulate this adaptation. This finding suggests that genes involved in mitochondrial function contribute to the response of ATP synthesis to exercise training. Diabetes 58:1333-1341, 200

    Classical signal model reproducing quantum probabilities for single and coincidence detections

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    We present a simple classical (random) signal model reproducing Born's rule. The crucial point of our approach is that the presence of detector's threshold and calibration procedure have to be treated not as simply experimental technicalities, but as the basic counterparts of the theoretical model. We call this approach threshold signal detection model (TSD). The experiment on coincidence detection which was done by Grangier in 1986 \cite{Grangier} played a crucial role in rejection of (semi-)classical field models in favor of quantum mechanics (QM): impossibility to resolve the wave-particle duality in favor of a purely wave model. QM predicts that the relative probability of coincidence detection, the coefficient g(2)(0),g^{(2)}(0), is zero (for one photon states), but in (semi-)classical models g(2)(0)1.g^{(2)}(0)\geq 1. In TSD the coefficient g(2)(0)g^{(2)}(0) decreases as 1/Ed2,1/{\cal E}_d^2, where Ed>0{\cal E}_d>0 is the detection threshold. Hence, by increasing this threshold an experimenter can make the coefficient g(2)(0)g^{(2)}(0) essentially less than 1. The TSD-prediction can be tested experimentally in new Grangier type experiments presenting a detailed monitoring of dependence of the coefficient g(2)(0)g^{(2)}(0) on the detection threshold

    Decision-Making and Depressive Symptomatology

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    Difficulty making decisions is a core symptom of depressive illness, but the nature of these difficulties has not been well characterized. The two studies presented herein use the same hypothetical scenarios that call for a decision. In Study 1, participants were asked to make and explain their decisions in a free-response format, as well as to describe their prior experiences with similar situations. The results suggest that those with more depressive symptoms make decisions that are less likely to further their interests. We also identified several interesting associations between features of decision-making and the presence of depressive symptoms. In Study 2, participants were guided through their decisions with simple decision tools to investigate whether the association between depressive symptoms and poor decisions is better accounted for by failure to use of good decision-making strategies, or by other factors, such as differences in priorities or goals. With this minimal intervention the quality of decisions no longer declined significantly as a function of depressive symptom severity. Moreover, few associations between depressive symptom severity and decision-related goals and priorities were evident, suggesting that the previously-exposed difficulties of depressed individuals with decision-making were largely the result of their failure to use effective decision-making techniques

    Inhibition of lipolysis in Type 2 diabetes normalizes glucose disposal without change in muscle glycogen synthesis rates

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    Suppression of lipolysis by acipimox is known to improve insulin-stimulated glucose disposal, and this is an important phenomenon. The mechanism has been assumed to be an enhancement of glucose storage as glycogen, but no direct measurement has tested this concept or its possible relationship to the reported impairment in insulin-stimulated muscle ATP production. Isoglycaemic–hyperinsulinaemic clamps with [13C]glucose infusion were performed on Type 2 diabetic subjects and matched controls with measurement of glycogen synthesis by 13C MRS (magnetic resonance spectroscopy) of muscle. 31P saturation transfer MRS was used to quantify muscle ATP turnover rates. Glucose disposal rates were restored to near normal in diabetic subjects after acipimox (6.2±0.8 compared with 4.8±0.6 mg·kgffm−1·min−1; P<0.01; control 6.6±0.5 mg·kgffm−1·min−1; where ffm, is fat-free mass). The increment in muscle glycogen concentration was 2-fold higher in controls compared with the diabetic group, and acipimox administration to the diabetic group did not increase this (2.0±0.8 compared with 1.9±1.1 mmol/l; P<0.05; control, 4.0±0.8 mmol/l). ATP turnover rates did not increase during insulin stimulation in any group, but a modest decrease in the diabetes group was prevented by lowering plasma NEFAs (non-esterified fatty acids; 8.4±0.7 compared with 7.1±0.5 μmol·g−1·min−1; P<0.05; controls 8.6±0.8 μmol·g−1·min−1). Suppression of lipolysis increases whole-body glucose uptake with no increase in the rate of glucose storage as glycogen but with increase in whole-body glucose oxidation rate. ATP turnover rate in muscle exhibits no relationship to the acute metabolic effect of insulin

    Techniques for temporal detection of neural sensitivity to external stimulation

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    We propose a simple measure of neural sensitivity for characterizing stimulus coding. Sensitivity is defined as the fraction of neurons that show positive responses to n stimuli out of a total of N. To determine a positive response, we propose two methods: Fisherian statistical testing and a data-driven Bayesian approach to determine the response probability of a neuron. The latter is non-parametric, data-driven, and captures a lower bound for the probability of neural responses to sensory stimulation. Both methods are compared with a standard test that assumes normal probability distributions. We applied the sensitivity estimation based on the proposed method to experimental data recorded from the mushroom body (MB) of locusts. We show that there is a broad range of sensitivity that the MB response sweeps during odor stimulation. The neurons are initially tuned to specific odors, but tend to demonstrate a generalist behavior towards the end of the stimulus period, meaning that the emphasis shifts from discrimination to feature learning
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