Empirical Issues in Lifetime Poverty Measurement

This paper demonstrates the implications of adopting an approach to measuring poverty that takes into account the lifetime experience of individuals rather than simply taking a static or cross-sectional perspective. Our approach follows the theoretical innovations in Hoy and Zheng (2008) which address various aspects of the specific pattern of any poverty spells experienced by an individual as well as a possible retrospective consideration that an individual might have concerning his life experience as a whole. For an individual, our perspective of lifetime poverty is influenced by both the snapshot poverty of each period and the poverty level of the permanent lifetime consumption; it is also influenced by how poverty spells are distributed over the lifetime. Using PSID data for the US, we demonstrate empirically the power of alternative axioms concerning how lifetime poverty should be measured when making pairwise comparisons of individual lifetime profiles of consumption (income) experiences. We also demonstrate the importance of taking a lifetime view of poverty in comparing poverty between groups by use of the classic FGT ‘snapshot’ poverty index in conjunction with period weighting functions that explicitly reflect concerns about the pattern of poverty spells over individuals’ lifetimes.Lifetime poverty, snapshot poverty, chronic poverty, early poverty, poverty measurement

Diurnal variation in harbour porpoise detection – potential implications for management

Peer reviewedPublisher PD

Pure and loaded fireballs in SGR giant flares

On December 27, 2004, a giant flare from SGR 1806$-$20 was detected on earth. Its thermal spectrum and temperature suggest that the flare resulted from an energy release of about $10^{47}$ erg/sec close to the surface of a neutron star in the form of radiation and/or pairs. This plasma expanded under its own pressure producing a fireball and the observed gamma-rays escaped once the fireball became optically thin. The giant flare was followed by a bright radio afterglow, with an observable extended size, implying an energetic relativistic outflow. We revisit here the evolution of relativistic fireballs and we calculate the Lorentz factor and energy remaining in relativistic outflow once the radiation escapes. We show that pairs that arise naturally in a pure pairs-radiation fireball do not carry enough energy to account for the observed afterglow. We consider various alternatives and we show that if the relativistic outflow that causes the afterglow is related directly to the prompt flare, then the initial fireball must be loaded by baryons or Poynting flux. While we focus on parameters applicable to the giant flare and the radio afterglow of SGR 1806$-$20 the calculations presented here might be also applicable to GRBs

Reproduction in Reptiles, from Genes to Ecology: A Retrospective and Prospective Vision

The 6th World Congress of Herpetology (WCH), held in Manaus, Brazil in 2008, provided an excellent venue for a broad, integrative symposium on reproduction in reptiles. This symposium brought together researchers from throughout the world who are working on diverse reptilian species. The symposium’s title “Reproduction in Reptiles from Genes to Ecology,” captures the methodological breadth of contemporary research as well as its integrative nature. This special issue of Herpetological Conservation and Biology presents a series of papers from contributors to that symposium. In this introduction to the special issue, we offer an evolutionary overview of reptilian reproduction and summarize the nature, characteristics, and implications of current research efforts, as represented in the WCH symposium

Superconductivity in SrNi2As2 Single Crystals

The electrical resistivity \rho(T) and heat capacity C(T) on single crystals of SrNi2As2 and EuNi2As2 are reported. While there is no evidence for a structural transition in either compound, SrNi2As2 is found to be a bulk superconductor at T_c=0.62 K with a Sommerfeld coefficient of \gamma= 8.7 mJ/mol K^2 and a small upper critical field H_{c2} \sim 200 Oe. No superconductivity was found in EuNi2As2 above 0.4 K, but anomalies in \rho and C reveal that magnetic order associated with the Eu^{2+} magnetic moments occurs at T_m = 14 K.Comment: 8 pages, 5 figure

Epistemic decision theory applied to multiple-target tracking

A decision philosophy that seeks the avoidance of error by trading off belief of truth and value of information is applied to the problem of recognizing tracks from multiple targets (MTT). A successful MTT methodology should be robust in that its performance degrades gracefully as the conditions of the collection become less favorable to optimal operation. By stressing the avoidance, rather than the explicit minimization, of error, the authors obtain a decision rule for trajectory-data association that does not require the resolution of all conflicting hypotheses when the database does not contain sufficient information to do so reliably. This rule, coupled with a set-valued Kalman filter for trajectory estimation, results in a methodology that does not attempt to extract more information from the database than it contains