Fermi Large Area Telescope Constraints on the Gamma-ray Opacity of the Universe

The Extragalactic Background Light (EBL) includes photons with wavelengths from ultraviolet to infrared, which are effective at attenuating gamma rays with energy above ~10 GeV during propagation from sources at cosmological distances. This results in a redshift- and energy-dependent attenuation of the gamma-ray flux of extragalactic sources such as blazars and Gamma-Ray Bursts (GRBs). The Large Area Telescope onboard Fermi detects a sample of gamma-ray blazars with redshift up to z~3, and GRBs with redshift up to z~4.3. Using photons above 10 GeV collected by Fermi over more than one year of observations for these sources, we investigate the effect of gamma-ray flux attenuation by the EBL. We place upper limits on the gamma-ray opacity of the Universe at various energies and redshifts, and compare this with predictions from well-known EBL models. We find that an EBL intensity in the optical-ultraviolet wavelengths as great as predicted by the "baseline" model of Stecker et al. (2006) can be ruled out with high confidence.Comment: 42 pages, 12 figures, accepted version (24 Aug.2010) for publication in ApJ; Contact authors: A. Bouvier, A. Chen, S. Raino, S. Razzaque, A. Reimer, L.C. Reye

Global warming and recurrent mass bleaching of corals

During 2015–2016, record temperatures triggered a pan-tropical episode of coral bleaching, the third global-scale event since mass bleaching was first documented in the 1980s. Here we examine how and why the severity of recurrent major bleaching events has varied at multiple scales, using aerial and underwater surveys of Australian reefs combined with satellite-derived sea surface temperatures. The distinctive geographic footprints of recurrent bleaching on the Great Barrier Reef in 1998, 2002 and 2016 were determined by the spatial pattern of sea temperatures in each year. Water quality and fishing pressure had minimal effect on the unprecedented bleaching in 2016, suggesting that local protection of reefs affords little or no resistance to extreme heat. Similarly, past exposure to bleaching in 1998 and 2002 did not lessen the severity of bleaching in 2016. Consequently, immediate global action to curb future warming is essential to secure a future for coral reefs

“A General Separation of Colored and White”: the WWII riots, military segregation, and racism(s) beyond the White/Nonwhite binary

This article uses archival research to explore important differences in the discursive and institutional positioning of Mexican American and African American men during World War II. Through the focal point of the riots which erupted in Los Angeles and other major cities in the summer of 1943, I examine the ways in which black and Mexican ‘rioters’ were imagined in official and popular discourses. Though both groups of youth were often constructed as deviant and subversive, there were also divergences in the ways in which their supposed racial difference was discursively configured. I also consider the experiences of each group in the WWII military, a subject that has received little attention in previous work on the riots. Though both groups were subject to discrimination and brutality on the home front, only African Americans were segregated in the military - a fact that profoundly influenced the 1943 riots. Examining the very different conditions under which these men served, as well as the distinct ways in which their presence within the military and on the home front was interpreted and given meaning by press, law enforcement and military officials helps to illuminate the uneven and complex workings of racism in America, disrupting the common conceptualization of a definitive white/nonwhite color line

Concept and design of a genome-wide association genotyping array tailored for transplantation-specific studies

Background: In addition to HLA genetic incompatibility, non-HLA difference between donor and recipients of transplantation leading to allograft rejection are now becoming evident. We aimed to create a unique genome-wide platform to facilitate genomic research studies in transplant-related studies. We designed a genome-wide genotyping tool based on the most recent human genomic reference datasets, and included customization for known and potentially relevant metabolic and pharmacological loci relevant to transplantation. Methods: We describe here the design and implementation of a customized genome-wide genotyping array, the ‘TxArray’, comprising approximately 782,000 markers with tailored content for deeper capture of variants across HLA, KIR, pharmacogenomic, and metabolic loci important in transplantation. To test concordance and genotyping quality, we genotyped 85 HapMap samples on the array, including eight trios. Results: We show low Mendelian error rates and high concordance rates for HapMap samples (average parent-parent-child heritability of 0.997, and concordance of 0.996). We performed genotype imputation across autosomal regions, masking directly genotyped SNPs to assess imputation accuracy and report an accuracy of >0.962 for directly genotyped SNPs. We demonstrate much higher capture of the natural killer cell immunoglobulin-like receptor (KIR) region versus comparable platforms. Overall, we show that the genotyping quality and coverage of the TxArray is very high when compared to reference samples and to other genome-wide genotyping platforms. Conclusions: We have designed a comprehensive genome-wide genotyping tool which enables accurate association testing and imputation of ungenotyped SNPs, facilitating powerful and cost-effective large-scale genotyping of transplant-related studies. Electronic supplementary material The online version of this article (doi:10.1186/s13073-015-0211-x) contains supplementary material, which is available to authorized users

The rise and fall of mob violence against Mexicans in Arizona, 1859-1915

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'Mexican Perspectives on Mob Violence in the United States'

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Cycles of lynching the U.S.-Mexico border and mob violence against persons of mexican descent in the United States, 1848–1928

The U.S.-Mexico border has earned an enduring reputation as a site of violence. During the past twenty years in particular, the drug wars—fueled by the international movement of narcotics and vast sums of money—have burned an abiding image of the border as a place of endemic danger into the consciousness of both countries. By the media, popular culture, and politicians, mayhem and brutality are often portrayed as the unavoidable birthright of this transnational space. Through multiple perspectives from both sides of the border, the collected essays in These Ragged Edges directly challenge that idea, arguing that rapidly changing conditions along the U.S.-Mexico border through the nineteenth, twentieth, and twenty-first centuries have powerfully shaped the ebb and flow of conflict within the region. By diving deeply into diverse types of violence, contributors dissect the roots and consequences of border violence across numerous eras, offering a transnational analysis of how and why violence has affected the lives of so many inhabitants on both sides of the border