Radio light curves during the passage of cloud G2 near Sgr A*

We calculate radio light curves produced by the bow shock that is likely to form in front of the G2 cloud when it penetrates the accretion disk of Sgr A*. The shock acceleration of the radio-emitting electrons is captured self-consistently by means of first-principles particle-in-cell simulations. We show that the radio luminosity is expected to reach maximum in early 2013, roughly a month after the bow shock crosses the orbit pericenter. We estimate the peak radio flux at 1.4 GHz to be 1.4 - 22 Jy depending on the assumed orbit orientation and parameters. We show that the most promising frequencies for radio observations are in the 0.1<nu<1 GHz range, for which the bow shock emission will be much stronger than the intrinsic radio flux for all the models considered.Comment: 15 pages, 10 figures, accepted for publication in MNRA

Expectancy-value model related to physical activity behaviors in chilean and spanish adolescents

The purpose of the study is to comparatively test the expectancy-value model in Chilean and Spanish samples. The model proposes: a social world (composed of social support, physical activity teasing, and weight teasing), expectancy (composed of perceived competence and appearance), task values (composed of enjoyment and stress) to predict physical activity and intention to be physically active. Participants were 497 (Chilean) and 1365 (Spanish) adolescents. Structural equation models and multi-group modelling were used. All the models presented adequate fit to the data. The results show that physical activity teasing is a contextual and essential variable; perceived competence and enjoyment influenced physical activity and intentions to be physically active; some differences appeared in the prediction of physical activity and intentions to be physically active when the multi-group model was run. Culturally tailored interventions are key to improving physical activity (PA) behaviors

The catalytic Ornstein-Uhlenbeck process with superprocess catalyst

The main objective of this work is to study a natural class of catalytic Ornstein-Uhlenbeck (O-U) processes with a measure-valued random catalyst, for example, super-Brownian motion. We relate this to the class of affine processes that provides a unified setting in which to view Ornstein-Uhlenbeck processes, superprocesses, and Ornstein-Uhlenbeck processes with superprocess catalyst. We then review some basic properties of super-Brownian motion which we need and introduce the Ornstein-Uhlenbeck process with catalyst given by a superprocess. The main results are the affine characterization of the characteristic functional-Laplace transform of the joint catalytic O-U process and catalyst process and the identification of basic properties of the quenched and annealed versions of these processes.Comment: 23 page

Heatwaves and Novel Host Consumption Increase Overwinter Mortality of an Imperiled Wetland Butterfly

Disruptive effects of climate change include range shifts, phenological mismatches among consumers and producers, and population declines. While these biological alterations have been widely documented, studies identifying specific mechanisms linking climate change to population declines are scarce. Extreme events, such as heatwaves can have devastating effects on living organisms and are increasing in frequency as Earth warms. Hence, understanding the effects of heatwaves on insects is necessary to inform conservation efforts and to develop predictions of population dynamics under future climate scenarios. Here, we experimentally evaluated the effects of heatwaves on the survival and phenology of the Baltimore Checkerspot (Euphydryas phaeton phaeton), a wetland butterfly with imperiled populations that has incorporated a novel host. We performed laboratory manipulations (implementing realistic temperature regimes) to assess the effect of heatwaves during summer and winter on the survival and phenology of E. p. phaeton. In addition, we analyzed historical temperature records to quantify the incidence of heatwaves within E. p. phaeton’s range to assess their potential role in the decline of southeastern populations. We found that winter heatwaves with maximum temperatures of 20◦C can have more devastating effects on survival than summer heatwaves (up to 41◦C). Eggs endured acute heat stress during summer with no significant effects on phenology and survival; similarly, pre-overwintering larvae were robust to heatwave exposure, as only themost intense heatwave treatment reduced their survival (37% reduction compared to control conditions). By contrast, dormant larvae were the most vulnerable stage, as they lost from 2 to 6% of their body mass after a three-day summer heatwave. Furthermore, their exposure to winter heatwaves resulted in 75 to 100% mortality. Feeding on the native host provided higher resilience under thermal stress than feeding on the invasive, recently acquired host. Finally, both heatwave incidence and severity have increased in the southern range of E. p. phaeton in the period from 1894 to 2011. We show that warm winter days induced severe mortality, providing a mechanistic explanation of how climate change can trigger population declines in E. p. phaeton and other insects

Aula Verde: arte como experiencia ambiental.

Marco Abarca provides a fresh look into the ethics of creativity with explicit connections between process philosophy and environmental ethics. In doing so, professor Abarca describes a rehabilitation project where a group of community participants, consisting of parolees and probationers, transformed a decayed wooded area into a lush tropical forest. The reader is, in turn, brought to consider the power of lived metaphors as life changing aesthetic experiences.Marco Abarca provee una renovada visión sobre ética y creatividad haciendo explícita la conexión entre la filosofía de procesos y la ética ambiental. El profesor Abarca describe un proyecto de rehabilitación para personas cumpliendo sentencias penales que se realizó por medio de la restauración de un bosque urbano. Con su narrativa nos invita a reflexionar sobre las metáforas vividas como experiencias estéticas transformadoras de la vida misma