GRB 970228 Within the EMBH Model

We consider the gamma-ray burst of 1997 February 28 (GRB 970228) within the ElectroMagnetic Black Hole (EMBH) model. We first determine the value of the two free parameters that characterize energetically the GRB phenomenon in the EMBH model, that is to say the dyadosphere energy, $E_{dya}=5.1\times10^{52}$ ergs, and the baryonic remnant mass $M_{B}$ in units of $E_{dya}$, $B=M_{B}c^{2}/E_{dya}=3.0\times10^{-3}$. Having in this way estimated the energy emitted during the beam-target phase, we evaluate the role of the InterStellar Medium (ISM) number density (n$_{ISM}$) and of the ratio ${\cal R}$ between the effective emitting area and the total surface area of the GRB source, in reproducing the observed profiles of the GRB 970228 prompt emission and X-ray (2-10 keV energy band) afterglow. The importance of the ISM distribution three-dimensional treatment around the central black hole is also stressed in this analysis.Comment: 4 pages, 1 figure, to appear in the Proceedings of the Los Alamos "Gamma Ray Burst Symposium" in Santa Fe, New Mexico, September 8-12 2003 (AIP Conf. Ser.), CHAPTER: GRB Connection to Supernova

PTF 10bzf (SN 2010ah): A Broad-Line Ic Supernova Discovered by the Palomar Transient Factory

We present the discovery and follow-up observations of a broad-line Type Ic supernova (SN), PTF 10bzf (SN 2010ah), detected by the Palomar Transient Factory (PTF) on 2010 February 23. The SN distance is ≅218 Mpc, greater than GRB 980425/SN 1998bw and GRB 060218/SN 2006aj, but smaller than the other SNe firmly associated with gamma-ray bursts (GRBs). We conducted a multi-wavelength follow-up campaign with Palomar 48 inch, Palomar 60 inch, Gemini-N, Keck, Wise, Swift, the Allen Telescope Array, Combined Array for Research in Millimeter-wave Astronomy, Westerbork Synthesis Radio Telescope, and Expanded Very Large Array. Here we compare the properties of PTF 10bzf with those of SN 1998bw and other broad-line SNe. The optical luminosity and spectral properties of PTF 10bzf suggest that this SN is intermediate, in kinetic energy and amount of ^(56)Ni, between non-GRB-associated SNe like 2002ap or 1997ef, and GRB-associated SNe like 1998bw. No X-ray or radio counterpart to PTF 10bzf was detected. X-ray upper limits allow us to exclude the presence of an underlying X-ray afterglow as luminous as that of other SN-associated GRBs such as GRB 030329 or GRB 031203. Early-time radio upper limits do not show evidence for mildly relativistic ejecta. Late-time radio upper limits rule out the presence of an underlying off-axis GRB, with energy and wind density similar to the SN-associated GRB 030329 and GRB 031203. Finally, by performing a search for a GRB in the time window and at the position of PTF 10bzf, we find that no GRB in the interplanetary network catalog could be associated with this SN

Association between coverage of maternal and child health interventions, and under-5 mortality: a repeated cross-sectional analysis of 35 sub-Saharan African countries

Background: Infant and child mortality rates are among the most important indicators of child health, nutrition, implementation of key survival interventions, and the overall social and economic development of a population. In this paper, we investigate the role of coverage of maternal and child health (MNCH) interventions in contributing to declines in child mortality in sub-Saharan Africa. Design: Data are from 81 Demographic and Health Surveys from 35 sub-Saharan African countries. Using ecological time-series and child-level regression models, we estimated the effect of MNCH interventions (summarized by the percent composite coverage index, or CCI) on child mortality with in the first 5 years of life net of temporal trends and covariates at the household, maternal, and child levels. Results: At the ecologic level, a unit increase in standardized CCI was associated with a reduction in under-5 child mortality rate (U5MR) of 29.0 per 1,000 (95% CI: −43.2, −14.7) after adjustment for survey period effects and country-level per capita gross domestic product (pcGDP). At the child level, a unit increase in standardized CCI was associated with an odds ratio of 0.86 for child mortality (95% CI: 0.82–0.90) after adjustment for survey period effect, country-level pcGDP, and a set of household-, maternal-, and child-level covariates. Conclusions: MNCH interventions are important in reducing U5MR, while the effects of economic growth in sub-Saharan Africa remain weak and inconsistent. Improved coverage of proven life-saving interventions will likely contribute to further reductions in U5MR in sub-Saharan Africa

A Bayesian High-Frequency Estimator of the Multivariate Covariance of Noisy and Asynchronous Returns

A multivariate positive definite estimator of the integrated covariance matrix of noisy and asynchronously observed asset returns is proposed. We adopt a Bayesian Dynamic Linear Model where microstructure noise is interpreted as measurement error, and asynchronous trading as missing observations in an otherwise synchronous series. Missing observations are treated as any other parameter, as typical in a Bayesian framework. An augmented Gibbs algorithm is used since all full conditionals are available and its convergence and robustness are discussed. A realistic simulation study compares our estimator with existing alternatives, under different liquidity and microstructure noise conditions. The results suggest that our estimator is superior in terms of RMSE particularly under severe conditions, such as portfolios of assets with heterogeneous liquidity and high level of microstructure noise. The application to the empirical dataset of ten tick-by-tick stock price series confirms the simulation results

Association between socioeconomic status and self-reported diabetes in India: a cross-sectional multilevel analysis

Objectives: To quantify the association between socioeconomic status (SES) and type 2 diabetes in India. Design: Nationally representative cross-sectional household survey. Setting: Urban and rural areas across 29 states in India. Participants: 168 135 survey respondents aged 18–49 years (women) and 18–54 years (men). Primary outcome measure: Self-reported diabetes status. Results: Markers of SES were social caste, household wealth and education. The overall prevalence of self-reported diabetes was 1.5%; this increased to 1.9% and 2.5% for those with the highest levels of education and household wealth, respectively. In multilevel logistic regression models (adjusted for age, gender, religion, marital status and place of residence), education (OR 1.87 for higher education vs no education) and household wealth (OR 4.04 for richest quintile vs poorest) were positively related to self-reported diabetes (p40% of the population is living in poverty

On the basic mechanism of Pixelized Photon Detectors

A Pixelized Photon Detector (PPD) is a generic name for the semiconductor devices operated in the Geiger-mode, such as Silicon PhotoMultiplier and Multi-Pixel Photon Counter, which has high photon counting capability. While the internal mechanisms of the PPD have been intensively studied in recent years, the existing models do not include the avalanche process. We have simulated the multiplication and quenching of the avalanche process and have succeeded in reproducing the output waveform of the PPD. Furthermore our model predicts the existence of dead-time in the PPD which has never been numerically predicted. For serching the dead-time, we also have developed waveform analysis method using deconvolution which has the potential to distinguish neibouring pulses precisely. In this paper, we discuss our improved model and waveform analysis method.Comment: 4pages, 5figures, To appear in the proceedings of 5th International Conference on New Developments in Photodetection (NDIP08), Aix-les-Bains, France, 15-20 Jun 200

A phase-field model for fracture in beams from asymptotic results in 2D elasticity

We propose a derivation of a damage model in slender structures, focusing on the particular case of a rod. The peculiarity of the model is that it takes into account the changes in rigidity of the body, distinguishing between bending, traction and the possible mixed interactions between the two. The approach is based on a matched asymptotic expansion, taking the recent work of Baldelli et al [1] as starting point. Choosing the slenderness of the rod as small parameter for the asymptotic expansion, we determine the first order at which a correction occurs with respect to the Saint-Venant solution of the elastic problem, due to the presence of a crack. The results highlight that the presence of a defect affects in different ways the bending and traction rigidities of the rod, and that a coupling between the two deformation modes might occur, depending on the geometry of the crack. Moreover, the derivation allows to explicitly calculate the coefficients of this correction, for any given depth of the crack, by means of a simple numerical procedure. Application to the classic three-point bending problem is considered in order to highlight the predictive capabilities of the model. These results suggest ways in which state of the art phasefield models (e.g. [2]) for damage could be refined. This work goes in the direction of developing phase-field models suitable for application to slender structures, where the use of reduced dimensional models has proved promising [3]

Consumers’ preferences for biodiversity in vineyards: A choice experiment on wine

In recent years consumers\u2019 concerns regarding the environmental impact of food production has significantly increased, also due to food sustainability, food safety and food security issues. A number of certification systems for environmental-friendly products have been created e.g. water-saving labels and fishery sustainable labels. Among various environmental issues, the protection of biodiversity has recently gained popularity both in public opinion and in scientific debate. This paper describes the results of a Choice Experiment on wine consumers to estimate their willingness to pay for biodiversity conservation practices in vineyards. The survey was conducted by direct interviews at a wine tasting event in an Italian winery located at Montefano (Marche). The results show that consumers are willing to pay a premium price for wine certification that takes into account biodiversity not only for medium-high price wines, but also for low-price wines. Finally, quality of wine and organic certification remain important attributes in wine purchasing choices related to expensive wines

What drives farm structural change? An analysis of economic, demographic and succession factors

The evolution of farm size and land use are important determinants of the efficiency and profitability of agriculture and the configuration of the territory. In this paper, a conceptual framework of the evolution of the number of farms and land use is presented, arguing that a major determinant of the change in the number of farms is the presence or absence of successors to ageing farmers and that these socio-demographic variables shape the evolution of the sector in terms of farm size, while they do not significantly affect the changes in the farmed area. This hypothesis was empirically tested with data drawn from individual farm records of the Italian Agricultural Censuses of 2000 and 2010—aggregated at the municipality level for an Italian region—by estimating regressions on the decrease rates of the number of farms, the utilised agricultural area and the total agricultural area. The results support the conclusion that the change in the number of farms was largely determined by the absence of successors in family farms and by the average operators’ age, unlike the change in the farmed area, for which natural land conditions were the main drivers