Distribution of Spectral Characteristics and the Cosmological Evolution of GRBs

We investigate the cosmological evolution of GRBs, using the total gamma ray fluence as a measure of the burst strength. This involves an understanding of the distributions of the spectral parameters of GRBs as well as the total fluence distribution - both of which are subject to detector selection effects. We present new non-parametric statistical techniques to account for these effects, and use these methods to estimate the true distribution of the peak of the nu F_nu spectrum, E_p, from the raw distribution. The distributions are obtained from four channel data and therefore are rough estimates. Here, we emphasize the methods and present qualitative results. Given its spectral parameters, we then calculate the total fluence for each burst, and compute its cumulative and differential distributions. We use these distributions to estimate the cosmological rate evolution of GRBs, for three cosmological models. Our two main conclusions are the following: 1) Given our estimates of the spectral parameters, we find that there may exist a significant population of high E_p bursts that are not detected by BATSE, 2) We find a GRB co-moving rate density quite different from that of other extragalactic objects; in particular, it is different from the recently determined star formation rate.Comment: 20 pages, including 10 postscript figures. Submitted to Ap

Does Exposure and Receptivity to E-cigarette Advertisements Relate to E-cigarette and Conventional Cigarette Use Behaviors among Youth? Results from Wave 1 of the Population Assessment of Tobacco and Health Study

Background: E-cigarettes (EC) are the most commonly used tobacco product among youth. Additionally, youth EC users are progressing to smoking conventional cigarettes (CC). Although known to target youth, there are no current restrictions in the US on EC marketing, including advertising. The purpose of this study is to evaluate the relationship between EC advertisements and youth EC and CC use behaviors. Methods: This study analyzed data from youth (12-17 years) aware of EC in Wave 1 (2013-2014) of the Population Assessment of Tobacco and Health (PATH) study (n=12,199). Weighted logistic regression models assessed whether exposure and receptivity to any of five randomized EC ads (two TV and three print) were associated with the outcomes of EC and CC behaviors of ever use, current (past 30 day) use, and susceptibility to future use. Additional analyses determined whether EC advertising exposure and EC and CC behaviors associations were moderated by EC advertising receptivity. All models were adjusted for sociodemographics, other combustible tobacco product use, and parent smoking. Results: EC advertisement exposure was significantly associated to ever and current EC use as well as susceptibility to EC and CC (p Conclusion: These findings demonstrate exposure to EC advertisements are particularly associated with EC use behaviors, but could play a role in future CC use as well. Youth who are receptive to EC advertisements appear particularly vulnerable. Further studies should focus on the role of receptivity to EC advertisements among youth in order to support regulatory policy targeting EC advertising

Gestational dating by metabolic profile at birth: a California cohort study.

BackgroundAccurate gestational dating is a critical component of obstetric and newborn care. In the absence of early ultrasound, many clinicians rely on less accurate measures, such as last menstrual period or symphysis-fundal height during pregnancy, or Dubowitz scoring or the Ballard (or New Ballard) method at birth. These measures often underestimate or overestimate gestational age and can lead to misclassification of babies as born preterm, which has both short- and long-term clinical care and public health implications.ObjectiveWe sought to evaluate whether metabolic markers in newborns measured as part of routine screening for treatable inborn errors of metabolism can be used to develop a population-level metabolic gestational dating algorithm that is robust despite intrauterine growth restriction and can be used when fetal ultrasound dating is not available. We focused specifically on the ability of these markers to differentiate preterm births (PTBs) (<37 weeks) from term births and to assign a specific gestational age in the PTB group.Study designWe evaluated a cohort of 729,503 singleton newborns with a California birth in 2005 through 2011 who had routine newborn metabolic screening and fetal ultrasound dating at 11-20 weeks' gestation. Using training and testing subsets (divided in a ratio of 3:1) we evaluated the association among PTB, target newborn characteristics, acylcarnitines, amino acids, thyroid-stimulating hormone, 17-hydroxyprogesterone, and galactose-1-phosphate-uridyl-transferase. We used multivariate backward stepwise regression to test for associations and linear discriminate analyses to create a linear function for PTB and to assign a specific week of gestation. We used sensitivity, specificity, and positive predictive value to evaluate the performance of linear functions.ResultsAlong with birthweight and infant age at test, we included 35 of the 51 metabolic markers measured in the final multivariate model comparing PTBs and term births. Using a linear discriminate analyses-derived linear function, we were able to sort PTBs and term births accurately with sensitivities and specificities of ≥95% in both the training and testing subsets. Assignment of a specific week of gestation in those identified as PTBs resulted in the correct assignment of week ±2 weeks in 89.8% of all newborns in the training and 91.7% of those in the testing subset. When PTB rates were modeled using the metabolic dating algorithm compared to fetal ultrasound, PTB rates were 7.15% vs 6.11% in the training subset and 7.31% vs 6.25% in the testing subset.ConclusionWhen considered in combination with birthweight and hours of age at test, metabolic profile evaluated within 8 days of birth appears to be a useful measure of PTB and, among those born preterm, of specific week of gestation ±2 weeks. Dating by metabolic profile may be useful in instances where there is no fetal ultrasound due to lack of availability or late entry into care

Chylous Leak During Posterior Approach to Juvenile Scoliosis Surgery: A Case Report.

CaseWe report the first documented case of chylous leak recognized intraoperatively during posterior spinal instrumentation and fusion for juvenile scoliosis in a female patient with a history of thoracotomy and decortication for an empyema.ConclusionsThoracic duct injury can lead to severe morbidity and mortality because of chylothorax formation. Although chylous leaks are a well-documented complication of the anterior approach to spine surgery, leaks during the posterior approach are rarely reported. When these chylous leaks are recognized intraoperatively, the likelihood of serious complications may be minimized by drain placement before closure

Blimp-1-dependent and -independent natural antibody production by B-1 and B-1-derived plasma cells.

Natural antibodies contribute to tissue homeostasis and protect against infections. They are secreted constitutively without external antigenic stimulation. The differentiation state and regulatory pathways that enable continuous natural antibody production by B-1 cells, the main cellular source in mice, remain incompletely understood. Here we demonstrate that natural IgM-secreting B-1 cells in the spleen and bone marrow are heterogeneous, consisting of (a) terminally differentiated B-1-derived plasma cells expressing the transcriptional regulator of differentiation, Blimp-1, (b) Blimp-1+, and (c) Blimp-1neg phenotypic B-1 cells. Blimp-1neg IgM-secreting B-1 cells are not simply intermediates of cellular differentiation. Instead, they secrete similar amounts of IgM in wild-type and Blimp-1-deficient (PRDM-1ΔEx1A) mice. Blimp-1neg B-1 cells are also a major source of IgG3. Consequently, deletion of Blimp-1 changes neither serum IgG3 levels nor the amount of IgG3 secreted per cell. Thus, the pool of natural antibody-secreting B-1 cells is heterogeneous and contains a distinct subset of cells that do not use Blimp-1 for initiation or maximal antibody secretion

Do assumptions about the central density of subhaloes affect dark matter annihilation and lensing calculations?

A growing body of evidence suggests that the central density of cuspy dark matter subhaloes is conserved in minor mergers. However, empirical models of subhalo evolution, calibrated from simulations, often assume a drop in the central density. Since empirical models of subhaloes are used in galaxy-galaxy lensing studies and dark matter annihilation calculations, we explore the consequences of assuming different subhalo models. We find that dark matter annihilation calculations are very sensitive to the assumed subhalo mass profile, and different models can give more than a magnitude difference in the J-factor and boost factor in individual haloes. On the other hand, the shear and convergence profiles used in galaxy-galaxy lensing are sensitive to the initial profile assumed (e.g., NFW versus Einato) but are otherwise well-approximated by a simple model in which the original profile is sharply truncated. We conclude that since the innermost parts of haloes are difficult to resolve in simulations, it is important to have a theoretical understanding of how subhaloes evolve to make accurate predictions of the dark matter annihilation signal.Comment: 15 pages, 13 figures. Submitted to MNRA