Bayesian astrostatistics: a backward look to the future

This perspective chapter briefly surveys: (1) past growth in the use of Bayesian methods in astrophysics; (2) current misconceptions about both frequentist and Bayesian statistical inference that hinder wider adoption of Bayesian methods by astronomers; and (3) multilevel (hierarchical) Bayesian modeling as a major future direction for research in Bayesian astrostatistics, exemplified in part by presentations at the first ISI invited session on astrostatistics, commemorated in this volume. It closes with an intentionally provocative recommendation for astronomical survey data reporting, motivated by the multilevel Bayesian perspective on modeling cosmic populations: that astronomers cease producing catalogs of estimated fluxes and other source properties from surveys. Instead, summaries of likelihood functions (or marginal likelihood functions) for source properties should be reported (not posterior probability density functions), including nontrivial summaries (not simply upper limits) for candidate objects that do not pass traditional detection thresholds.Comment: 27 pp, 4 figures. A lightly revised version of a chapter in "Astrostatistical Challenges for the New Astronomy" (Joseph M. Hilbe, ed., Springer, New York, forthcoming in 2012), the inaugural volume for the Springer Series in Astrostatistics. Version 2 has minor clarifications and an additional referenc

Historia de las creencias y ceremonias religiosas de todos los pueblos

Es reimp. de la ed. de París

Bayesian Analysis of the (Generalized) Chaplygin Gas and Cosmological Constant Models using the 157 gold SNe Ia Data

The generalized Chaplygin gas model (GCGM) contains 5 free parameters, here, they are constrained through the type Ia supernovae data, i.e., the ``gold sample'' of 157 supernovae data. Negative and large positive values for $\alpha$ are taken into account. The analysis is made by employing the Bayesian statistics and the prediction for each parameter is obtained by marginalizing on the remained ones. This procedure leads to the following predictions: $\alpha = - 0.75^{+4.04}_{-0.24}$, $H_0=65.00^{+1.77}_{-1.75}$, $\Omega_{k0} = - 0.77^{+1.14}_{-5.94}$, $\Omega_{m0} = 0.00^{+1.95}_{-0.00}$, $\Omega_{c0} = 1.36^{+5.36}_{-0.85}$, $\bar A = 1.000^{+0.000}_{-0.534}$. Through the same analysis the specific case of the ordinary Chaplygin gas model (CGM), for which $\alpha = 1$, is studied. In this case, there are now four free parameters and the predictions for them are: $H_0 = 65.01^{+1.81}_{-1.71}$, $\Omega_{k0} = - 2.73^{+1.53}_{-0.97}$, $\Omega_{m0} = 0.00^{+1.22}_{-0.00}$, $\Omega_{c0} = 1.34^{+0.94}_{-0.70}$, $\bar A = 1.000^{+0.000}_{-0.270}$. To complete the analysis the $\Lambda$CDM, with its three free parameters, is considered. For all these models, particular cases are considered where one or two parameters are fixed. The age of the Universe, the deceleration parameter and the moment the Universe begins to accelerate are also evaluated. The quartessence scenario, is favoured. A closed (and in some cases a flat) and accelerating Universe is also preferred. The CGM case $\alpha = 1$ is far from been ruled out, and it is even preferred in some particular cases. In most of the cases the $\Lambda$CDM is disfavoured with respect to GCGM and CGM.Comment: 23 pages, LaTeX 2e, 6 tables, 38 EPS figures, uses graphic

Type Ia Supernovae, Evolution, and the Cosmological Constant

We explore the possible role of evolution in the analysis of data on SNe Ia at cosmological distances. First, using a variety of simple sleuthing techniques, we find evidence that the properties of the high and low redshift SNe Ia observed so far differ from one another. Next, we examine the effects of including simple phenomenological models for evolution in the analysis. The result is that cosmological models and evolution are highly degenerate with one another, so that the incorporation of even very simple models for evolution makes it virtually impossible to pin down the values of $\Omega_M$ and $\Omega_\Lambda$, the density parameters for nonrelativistic matter and for the cosmological constant, respectively. Moreover, we show that if SNe Ia evolve with time, but evolution is neglected in analyzing data, then, given enough SNe Ia, the analysis hones in on values of $\Omega_M$ and $\Omega_\Lambda$ which are incorrect. Using Bayesian methods, we show that the probability that the cosmological constant is nonzero (rather than zero) is unchanged by the SNe Ia data when one accounts for the possibility of evolution, provided that we do not discriminate among open, closed and flat cosmologies a priori. The case for nonzero cosmological constant is stronger if the Universe is presumed to be flat, but still depends sensitively on the degree to which the peak luminosities of SNe Ia evolve as a function of redshift. The estimated value of $H_0$, however, is only negligibly affected by accounting for possible evolution.Comment: 45 pages, 15 figures; accepted for publication in The Astrophysical Journal. Minor revisions and clarifications made including addition of recent reference

Validity of BMI-based Equations for Estimating Body Fat Percentage in Collegiate Male Soccer Players: A Three-Compartment Model Comparison

The ease of calculating body mass index (BMI)-based body fat percentage (BF%) is appealing in collegiate male soccer player who have limited time availability and strict training regimens. However, research has yet to evaluate whether BMI-based BF% equations are valid when compared to a criterion multi-compartment model. PURPOSE: The purpose of this study was to compare BMI-based BF% equations with a three-compartment (3C) model in collegiate male soccer players. METHODS: Sixteen NCAA Division II male soccer players (age = 21 ± 2 years; ht = 179.0 ± 8.2 cm; wt = 78.0 ± 8.5 kg) participated in this study. BMI was calculated as weight (kg) divided by height squared (m2). BF% was predicted with the BMI-based equations of Jackson et al. (BMIJA), Deurenberg et al. (BMIDE) Gallagher et al. (BMIGA), and Womersley and Durnin (BMIWO). The criterion 3C model BF% was determined using air displacement plethysmography (BOD POD®) for body volume and bioimpedance spectroscopy for total body water. RESULTS: The BMI-based BF% equations significantly overestimated mean group BF% for all equations when compared to the 3C model (2.78 to 5.18%; all p \u3c 0.05). The standard error of estimate ranged from 4.18 (BMIDE) to 4.29% (BMIWO). Furthermore, the 95% limits of agreement were similar for all comparisons and ranged from ±7.96 (BMIGA) to 8.18% (BMIJA). CONCLUSIONS: The results of this study demonstrate that the selected BMI-based BF% equations produce fairly small SEEs and 95% limits of agreement. However, the equations also revealed systematic error and a tendency to overestimate mean group BF% when compared to the 3C model. BMI-based equations can be used as an alternative for the individual estimation of BF% in collegiate male soccer players when a more advanced 3C model is not available, but practitioners should consider adjusting for the systematic error (e.g., decrease BMIDE by 2.78%)

Measuring Entanglement in a Photonic Embedding Quantum Simulator

Measuring entanglement is a demanding task that usually requires full tomography of a quantum system, involving a number of observables that grows exponentially with the number of parties. Recently, it was suggested that adding a single ancillary qubit would allow for the efficient measurement of concurrence, and indeed any entanglement monotone associated to antilinear operations. Here, we report on the experimental implementation of such a device---an embedding quantum simulator---in photonics, encoding the entangling dynamics of a bipartite system into a tripartite one. We show that bipartite concurrence can be efficiently extracted from the measurement of merely two observables, instead of fifteen, without full tomographic information.Comment: Updated versio

Vascular Effects of PHYSALIA PHYSALIS Venom

The purpose of this study was to identify the effects of Physalia physalis (Portuguese Man-of-War) venom on vascular smooth muscle and elucidate its mode of action. We utilized the in vivo approach by functionally isolating the skeletal muscle vasculature of the dog\u27s hind leg, and the in vitro approach by studying rabbit arterial ring segments. Twelve male mongrel dogs were anesthetized with 35 mg/kg sodium pentobarbital. Arterial pressure was measured from the aortic arch and the cranial femoral artery, a cephalad branch of the femoral artery. The skeletal muscle venous blood flow of the hind leg was functionally isolated. Femoral vein blood flow and pressure were monitored from ports in the extracorporeal flow sensor. Four of the twelve dogs were also subjected to lumbar sympathetic chain stimulation. Lingual, renal, femoral and central ear arterial ring segments were excised from 19 male California rabbits, weighing less than 2.7 kg. These vascular segments were each mounted on an isometric tension measuring device and placed in a 15 ml bath filled with Krebs-Henseleit solution aerated with 95% O2 and 5% CC^. Each ring was set at its optimum basal tension by applying passive stretch and inducing constriction with norepinephrine. The venom was added to the bath in logarithmically spaced doses, ranging from 0.021 yg/ml to 4.28 yg/ml. It was found that Physalia venom increased skeletal muscle blood flow when it was injected into the cranial femoral artery. The effect of the venom was diminished by cimetidine and tripelennamine (histamine receptor blockers), and was blocked by sodium meclofenamate (prostaglandin synthesis inhibitor). The venom transiently reversed sympathetic vasoconstriction, and no change of this effect was noted with infusion of cocaine. Venous blood samples taken after infusion of the venom revealed higher histamine levels than the control samples. The venom produced relaxation of the arterial ring segments in a sigmoid dose-dependent manner. The femoral artery displayed the greatest sensitivity to the venom, but the highest efficacy was demonstrated on the lingual artery. This effect was almost completely blocked by pretreatment with sodium meclofenamate. Venom induced relaxation was slightly enhanced by pretreatment with propranolol, but not significantly from control. Quinacrine (phospholipase A2inhibitor) and atropine had no effect on venom-induced relaxation. These observations suggest that Portuguese Man-of-War venom is a vasodilator, and that the primary mode of action is through stimulation of the synthesis of vasodilatory prostaglandins from substrates that are independent of phospholipase A2 activity

Sex differences in comorbidity between substance use and mental health in adolescents: Two sides of the same coin

Background: This study aims to evaluate sex differences in alcohol and cannabis use and mental health disorders (MHD) in adolescents, and to evaluate the predictive role of mental health disorders for alcohol and cannabis use disorders (AUD and CUD respectively). Method: A sample of 863 adolescents from the general population (53.7% girls, Mage = 16.62, SD = 0.85) completed a computerized battery including questions on substance use frequency, the Brief Symptom Inventory, the Cannabis Problems Questionnaire for Adolescents - Short version, the Rutgers Alcohol Problem Index and the DSM-IV-TR criteria for AUD and CUD. Bivariate analyses and binary logistic regressions were performed. Results: Girls presented significantly more mental health problems and a higher prevalence of comorbidity between SUD and MHD. Obsessivecompulsive symptoms and phobic anxiety indicated a higher risk of AUD, whereas depression and interaction between hostility and obsessivecompulsive disorder indicated a higher risk of CUD. Conclusions: Comorbidity between SUD and MHD is high among adolescents, and significantly higher among girls. Antecedentes: el objetivo de esta investigación es evaluar las diferencias de sexo en el uso de cannabis y alcohol y en trastornos de salud mental TSM en adolescentes, y el rol predictivo de los TSM sobre los trastornos por uso de alcohol y cannabis (TUA y TUC, respectivamente). Método: una muestra de 863 adolescentes de la población general (53, 7% chicas, edad media = 16.62, DT = 0, 85) completaron una batería informatizada sobre la frecuencia de uso de sustancias, el Inventario Breve de Síntomas, el Cuestionario de Problemas por Consumo de Cannabis - versión breve, el Índice de Rutgers de Problemas con el Alcohol y los criterios DSM-IV-TR para el TUA y TUC. Se realizaron análisis bivariados y de regresión logística binaria. Resultados: las chicas presentaron significativamente más problemas de salud mental y mayor prevalencia de comorbilidad entre TUS y TSM. El trastorno obsesivo-compulsivo (TOC) y la ansiedad fóbica indicaron un mayor riesgo de TUA, mientras que la depresión y la interacción entre hostilidad y TOC indicaron mayor riesgo de TUC. Conclusiones: la comorbilidad entre TUS y TSM es alta entre los adolescentes, y significativamente mayor entre las chicas

The Virgo Alignment Puzzle in Propagation of Radiation on Cosmological Scales

We reconsider analysis of data on the cosmic microwave background on the largest angular scales. Temperature multipoles of any order factor naturally into a direct product of axial quantities and cosets. Striking coincidences exist among the axes associated with the dipole, quadrupole, and octupole CMB moments. These axes also coincide well with two other axes independently determined from polarizations at radio and optical frequencies propagating on cosmological scales. The five coincident axes indicate physical correlation and anisotropic properties of the cosmic medium not predicted by the conventional Big Bang scenario. We consider various mechanisms, including foreground corrections, as candidates for the observed correlations. We also consider whether the propagation anomalies may be a signal of ``dark energy'' in the form of a condensed background field. Perhaps {\it light propagation} will prove to be an effective way to look for the effects of {\it dark energy}.Comment: 24 pages, 4 figures, minor changes, no change in result or conclusions. to appear in IJMP