Strategies for Imaging Faint Extended Sources in the Near-Infrared

Quantitative information about variations in the background at J and K' are presented and used to develop guidelines for the acquisition and reduction of ground-based images of faint extended sources in the near-infrared, especially those which occupy a significant fraction of the field of view of a detector or which are located in areas crowded with foreground or background sources. Findings are based primarily upon data acquired over three photometric nights with the 3.6x3.6 arcmin CFHT-IR array on the Canada-France-Hawaii Telescope atop Mauna Kea. Although some results are specific to CFHT, overall conclusions should be useful in guiding observing and reduction strategies of extended objects elsewhere.Comment: Accepted for publication in PASP July 2004. 29 pages, including 2 tables and 9 figure

Long-life mission reliability for outer planet atmospheric entry probes

The results of a literature analysis on the effects of prolonged exposure to deep space environment on the properties of outer planet atmospheric entry probe components are presented. Materials considered included elastomers and plastics, pyrotechnic devices, thermal control components, metal springs and electronic components. The rates of degradation of each component were determined and extrapolation techniques were used to predict the effects of exposure for up to eight years to deep space. Pyrotechnic devices were aged under accelerated conditions to an equivalent of eight years in space and functionally tested. Results of the literature analysis of the selected components and testing of the devices indicated that no severe degradation should be expected during an eight year space mission

Causality-based criteria for a negative refractive index must be used with care

Using the principle of causality as expressed in the Kramers-Kronig relations, we derive a generalized criterion for a negative refractive index that admits imperfect transparency at an observation frequency $\omega$. It also allows us to relate the global properties of the loss (i.e. its frequency response) to its local behaviour at $\omega$. However, causality-based criteria rely the on the group velocity, not the Poynting vector. Since the two are not equivalent, we provide some simple examples to compare the two criteria.Comment: slightly longer version of published PR

Stress relaxation in F-actin solutions by severing

Networks of filamentous actin (F-actin) are important for the mechanics of most animal cells. These cytoskeletal networks are highly dynamic, with a variety of actin-associated proteins that control cross-linking, polymerization and force generation in the cytoskeleton. Inspired by recent rheological experiments on reconstituted solutions of dynamic actin filaments, we report a theoretical model that describes stress relaxation behavior of these solutions in the presence of severing proteins. We show that depending on the kinetic rates of assembly, disassembly, and severing, one can observe both length-dependent and length-independent relaxation behavior

A Longitudinal Examination of the Effects of Social Support on Homicide Across European Regions

Since its introduction, social support theory has received generally consistent empirical support. Tests of social support theory have, however, mostly been cross-sectional and restricted to U.S. and Western European analyses. Measures of social support have tended to be inconsistent across studies and narrowly operationalized. The present project offers a longitudinal test of Cullen’s (1994) social support theory using a more broadly defined measure of social support that is comparable across both Eastern and Western European countries. Using data gathered by Eurostat, this study applies “hybrid” regression panel analysis to test the effects of social support on homicide rates across European regions for 2000, 2005 and 2009. Results provide evidence for an effect of social support on homicide between Western and Eastern European regions and within those regions over time. The analyses also indicate that social support moderates the effect of economic deprivation on homicide across Western European regions, though not Eastern European regions

Spatial Tools for Integrated and Inclusive Landscape Governance: Toward a New Research Agenda

Participatory spatial tools—community mapping, PGIS, and others—find increasing resonance among research and non-governmental organizations to make stakeholder claims and community perspectives explicit for more inclusive landscape governance. In this paper, we situate the use of participatory spatial tools in debates on integrated landscape approaches and inclusive development. We show that using such spatial tools is not new but argue that their application for inclusive landscape governance requires a new research agenda that focuses on expanding the scope of application of the tools, improving the inclusivity of the processes, and developing new technologies