Cold gas in hot star clusters: the wind from the red supergiant W26 in Westerlund 1

The massive red supergiant (RSG) W26 in Westerlund 1 is one of a growing number of RSGs shown to have winds that are ionized from the outside in. The fate of this dense wind material is important for models of second generation star formation in massive star clusters. Mackey et al. (2014) showed that external photoionization can stall the wind of RSGs and accumulate mass in a dense static shell. We use 1D R-HD simulations of an externally photoionized wind to predict the Halpha and [NII] emission arising from photoionized winds both with and without a dense shell. We analyse spectra of the Halpha and [NII] emission in the environment around W26 and compare them with predicted synthetic emission. Simulations of slow winds that are decelerated into a dense shell show strongly limb-brightened line emission, with line radial velocities that are independent of the wind speed. Faster winds (>22 km/s) do not form a dense shell, have less limb-brightening, and the line radial velocity is a good tracer of the wind speed. The brightness of the [NII] and Halpha lines as a function of distance from W26 agrees reasonably well with observations when only the line flux is considered. The radial velocity disagrees, however: the brightest observed emission is blueshifted by ~25 km/s relative to the radial velocity of the star, whereas a spherically symmetric wind has the brightest emission at zero radial velocity. Our results show that the bright nebula surrounding W26 must be asymmetric; we suggest it is confined by external ram pressure from the wind of the nearby supergiant W9. We obtain a lower limit on the nitrogen abundance within the nebula of 2.35 times solar. The line ratio strongly favours photoionization over shock ionization, and so even if the observed nebula is pressure confined there should still be an ionization front and a photoionization-confined shell closer to the star.Comment: 12 pages plus appendices, accepted for publication in Astronomy & Astrophysics; abstract shortened to fit arXiv limit

Mother and Child

https://egrove.olemiss.edu/ssdocphoto_c/1310/thumbnail.jp

Book review: Manufacturing celebrity: Latino paparazzi and women reporters in Hollywood by Vanessa Díaz

In Manufacturing Celebrity: Latino Paparazzi and Women Reporters in Hollywood, Vanessa Díaz demystifies the role of the Latino paparazzi and women reporters in celebrity media production. At a time of great upheaval in labour markets, Díaz’s interdisciplinary analyses at the intersection of work, race, gender and media are particularly insightful and relevant, writes Jonathan Pye and Sara Castro Cantú. Manufacturing Celebrity: Latino Paparazzi and Women Reporters in Hollywood. Vanessa Díaz. Duke University Press. 2020

Book review: Manufacturing celebrity: Latino paparazzi and women reporters in Hollywood by Vanessa Díaz

In Manufacturing Celebrity: Latino Paparazzi and Women Reporters in Hollywood, Vanessa Díaz demystifies the role of the Latino paparazzi and women reporters in celebrity media production. At a time of great upheaval in labour markets, Díaz’s interdisciplinary analyses at the intersection of work, race, gender and media are particularly insightful and relevant, writes Jonathan Pye and Sara Castro Cantú. Manufacturing Celebrity: Latino Paparazzi and Women Reporters in Hollywood. Vanessa Díaz. Duke University Press. 2020

Role of Fiber Orientation in Atrial Arrythmogenesis

Electrical wave-front propagation in the atria is determined largely by local fiber orientation. Recent study suggests that atrial fibrillation (AF) progresses with enhanced anisotropy. In this work, a 3D rabbit atrial anatomical model at 20 × 20 × 20 μm3 resolution with realistic fiber orientation was constructed based on the novel contrast-enhanced micro-CT imaging. The Fenton-Karma cellular activation model was adapted to reproduce rabbit atrial action potential period of 80 ms. Diffusivities were estimated for longitudinal and transverse directions of the fiber orientation respectively. Pacing was conducted in the 3D anisotropic atrial model with a reducing S2 interval to facilitate initiation of atrial arrhythmia. Multiple simulations were conducted with varying values of diffusion anisotropy and stimulus locations to evaluate the role of anisotropy in initiating AF. Under physiological anisotropy conditions, a rapid right atrial activation was followed by the left atrial activation. Excitation waves reached the atrio-ventricular border where they terminated. Upon reduction of conduction heterogeneity, re-entry was initiated by the rapid pacing and the activation of both atrial chambers was almost simultaneous. Myofiber orientation is an effective mechanism for regulating atrial activation. Modification of myoarchitecture is proarrhythmic

Influencia de la adición de CuO sobre las propiedades dieléctricas y piezoeléctricas de cerámicos

Con el objetivo de evaluar la influencia del Cu sobre las propiedades dieléctricas y piezoeléctricas del K1/2Na1/2NbO3 (KNN) se sintetizó, por reacción en estado sólido, KNN dopado con diferentes concentraciones de CuO (0 a 2% mol). El análisis del material se realizó empleando mediciones de densidad por el método de Arquímedes, difracción de rayos X (DRX), espectroscopía Raman, microscopía electrónica de barrido (SEM), curvas de polarización, constante piezoeléctrica (d33) y espectroscopía de impedancia a temperatura ambiente. En general, se observó que el aditivo no logró mejorar las propiedades dieléctricas o piezoeléctricas. Pequeñas cantidades de CuO (0,5%mol) afectaron ligeramente el proceso de densificación, mientras que altas concentraciones incrementaron la porosidad. Asimismo, bajas concentraciones de CuO redujeron drásticamente los valores de d33, presumiblemente debido al efecto endurecedor del aditivo.In this paper the influence of Cu on dielectric and piezoelectric properties of K1/2Na1/2NbO3 (KNN) was evaluated. Samples were obtained by solid state reaction doping with CuO (0 to 2 mol%). The obtained samples were characterized by the Archimedes method, X-Ray diffraction, Raman spectroscopy, Scanning Electron Microscopy, polarization curves, piezoelectric constant (d33) and impedance spectroscopy at room temperature. In general, it was observed that doping does not improve dielectric and piezoelectric properties. Small amounts of CuO (0.5 mol%) slightly affected the densification process, while high concentrations increased the porosity of the samples. Also, low concentrations of CuO drastically reduced d33 values, presumably due to the hardening effect of the additive.Fil: Ramajo, Leandro Alfredo. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - Mar del Plata. Instituto de Inv.en Ciencia y Tecnol.materiales (i); Argentina;Fil: Taub, Jonathan. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - Mar del Plata. Instituto de Inv.en Ciencia y Tecnol.materiales (i), Argentina;Fil: Castro, Miriam Susana. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - Mar del Plata. Instituto de Inv.en Ciencia y Tecnol.materiales (i); Argentina

Organic agriculture and climate change in developing countries

Coffee is Nicaragua’s main organic product. There are 13,100 hectares of certified coffee. This area represents 10 percent of the total coffee production of Nicaragua and is managed by approximately 3,500 small producers. 90 percent of the organic coffee is sold for the export market. In Nicaragua a legal framework for organic farming as well as regulations for the development of environmental services payments exist (forest conservation, water management, biodiversity conservation, carbon sequestration). There are also studies on carbon sequestration and carbon emissions in agriculture, forestry and industry. However, there are no investigations relating specifically to organic agriculture and climate change. 2. Background investigation Since 2004, the Costa Rican Corporation for Training and Development CEDECO has been carrying out investigations on organic agriculture and climate change in Costa Rica, Cuba and Brazil. The research consists in comparison between organic and conventional systems in order to define climate relevant parameters. With this aim the project includes a model in which physical, chemical, socio-economical and biological parameters are taken into account as factors that can influence the GHG emissions, carbon sequestration and the energy efficiency of the evaluated cropping systems. Results of the Costa Rican research showed that organic coffee production reduces GHG emissions by 1 ton of carbon equivalent (Ceq) per hectare. If this is multiplied by the certified organic coffee area, we find a total GHG reduction of more than 13 thousand tons Ceq per year. In the voluntary carbon market this can represent approximately 300,000 USD yearly. For the 3,500 smallholder families this could deliver financial resources for projects to improve their livelihoods in their local communities. Moreover, results also show that, on average, organic coffee production needs 95% less total energy per ha than conventional coffee production. This presents further cost savings for the small organic coffee producers. As concerns carbon storage, the organic coffee production system accumulates more organic carbon in deep soil layers than conventional coffee production. Carbon sequestration is a further element that can be used as a parameter for environmental services. 3. Assessment and improvement of climate relevant techniques in organic coffee production Based on the above findings, CEDECO/UNA/FiBL proposes assessing and improving climate relevant techniques in organic coffee production in Nicaragua. A comparison of organic and conventional coffee production will be necessary in order to find out which parameters need to be taken into account along the full production chain. The results of the comparison between organic and conventional coffee production systems might offer the possibility to assess specifically which parameters and techniques can be used for environmental services in Nicaragua. A further aim of the proposal is to optimize climate relevant techniques during the life cycle and throughout the full value chain of organic coffee production. For example: how to obtain climate neutral coffee production, which compost technique has less GHG emissions and how can it be improved, how can the harvest residues be converted into biogas and energy that can be used in the rural areas etc. The following approaches will be used: 1. Research: on station and on farm 2. Dissemination: capacity building, exchange of experience, promotion, multiplication, networking 3. Policy dialogue The project processes shall include: 1. Participatory process 2. Linking stakeholders: producers, authorities, NGOs, research centres, etc. 3. Generating local know-how How development cooperation can promote organic agriculture as a solution for climate mitigation 1. Set up projects with smallholder groups to improve specific management techniques: • Fertility and carbon sequestration • Compost production • Biogas and energy production • Management of biodiversity • Management of wastes and natural resources 2. Research, dissemination and policy dialogue 3. Organic agriculture as excellent tool to mitigate climate change Organisation CEDECO: Corporación Educativa para el Desarrollo Costarricense, Costa Rica UNA: Universidad Nacional Agraria FiBL: 1FiBL 2 CEDEC

Essays: Color-blind or Race-conscious Policies

The debate between advocates color blind and race conscious policies has been perennial in the United States since Reconstruction and has recently been resuscitated in the popular press with the publication of Michelle Alexander’s The New Jim Crow: Mass Incarceration in the Age of Color Blindness (2010). Alexander’s book provided support for the race conscious side and students read Nathan Glazer’s Affirmative Discrimination: Ethnic Inequality and Public Policy (1975) for a defense of the color blind side. The debate was framed in an even-handed manner by a selection from Desmond King and Rogers M. Smith’s Still a House Divided: Race and Politics in Obama’s America (2011) , which argues for both approaches under certain circumstances