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

Fine-Scale Mapping of the 4q24 Locus Identifies Two Independent Loci Associated with Breast Cancer Risk

Background: A recent association study identified a common variant (rs9790517) at 4q24 to be associated with breast cancer risk. Independent association signals and potential functional variants in this locus have not been explored. Methods: We conducted a fine-mapping analysis in 55,540 breast cancer cases and 51,168 controls from the Breast Cancer Association Consortium. Results: Conditional analyses identified two independent association signals among women of European ancestry, represented by rs9790517 [conditional P = 2.51 × 10−4; OR, 1.04; 95% confidence interval (CI), 1.02–1.07] and rs77928427 (P = 1.86 × 10−4; OR, 1.04; 95% CI, 1.02–1.07). Functional annotation using data from the Encyclopedia of DNA Elements (ENCODE) project revealed two putative functional variants, rs62331150 and rs73838678 in linkage disequilibrium (LD) with rs9790517 (r2 ≥ 0.90) residing in the active promoter or enhancer, respectively, of the nearest gene, TET2. Both variants are located in DNase I hypersensitivity and transcription factor–binding sites. Using data from both The Cancer Genome Atlas (TCGA) and Molecular Taxonomy of Breast Cancer International Consortium (METABRIC), we showed that rs62331150 was associated with level of expression of TET2 in breast normal and tumor tissue. Conclusion: Our study identified two independent association signals at 4q24 in relation to breast cancer risk and suggested that observed association in this locus may be mediated through the regulation of TET2. Impact: Fine-mapping study with large sample size warranted for identification of independent loci for breast cancer risk

Discutindo a educação ambiental no cotidiano escolar: desenvolvimento de projetos na escola formação inicial e continuada de professores

A presente pesquisa buscou discutir como a Educação Ambiental (EA) vem sendo trabalhada, no Ensino Fundamental e como os docentes desta escola compreendem e vem inserindo a EA no cotidiano escolar., em uma escola estadual do município de Tangará da Serra/MT, Brasil. Para tanto, realizou-se entrevistas com os professores que fazem parte de um projeto interdisciplinar de EA na escola pesquisada. Verificou-se que o projeto da escola não vem conseguindo alcançar os objetivos propostos por: desconhecimento do mesmo, pelos professores; formação deficiente dos professores, não entendimento da EA como processo de ensino-aprendizagem, falta de recursos didáticos, planejamento inadequado das atividades. A partir dessa constatação, procurou-se debater a impossibilidade de tratar do tema fora do trabalho interdisciplinar, bem como, e principalmente, a importância de um estudo mais aprofundado de EA, vinculando teoria e prática, tanto na formação docente, como em projetos escolares, a fim de fugir do tradicional vínculo “EA e ecologia, lixo e horta”.Facultad de Humanidades y Ciencias de la Educació

Bedload Transport in SE Asian Streams—Uncertainties and Implications for Reservoir Management

This paper reviews the current state of knowledge regarding bedload transport in SE Asian streams and presents the results from a case study on bedload transport in a mountain stream in northern Thailand. Together, the review and new data help contextualize the paucity of work done in the region in the face of a rapid increase in development and reservoir building throughout SE Asia. Data from both the reviewed studies and the case study indicate that bedload transport in many SE Asian streams (e.g. catchment areas \u3c 100 km2) is often much higher than is commonly assumed for tropical streams (i.e., about 10% of the total sediment load). Estimated annual bedload proportion was 18% of the total annual sediment load in the 74-km2 Mae Sa Catchment in northern Thailand. Bedload transport rates ranged from 0.001 to 1.1 kg s−1; and measured total suspended solid (TSS) rates ranged from 0.01 to 39 kg s−1, equivalent to TSS concentrations of 20 to 14,000 mg l−1 (associated with flows ranging from 0.4 to 30 m3 s−1). Event and annual loads of bedload and TSS were determined from rating curves based on automated measurements of discharge and turbidity (for TSS only). When taking uncertainty into account, the estimated range for the bedload proportion of total sediment load was 9–25% (equivalent to a yield of 81–279 Mg km−2y−1). The corresponding TSS yield estimate ranged from 649 to 1037 Mg km−2; and the total sediment load is an estimated 730–1313 Mg km−2 y−1. The proportion of bedload was lower than that reported in some other Asia streams, probably due to the occurrence of extended periods with high TSS that dampened the bedload signal, which was sand-dominated during the low-energy events that were sampled. Nevertheless, the bedload rate was generally higher than for most SE Asian locations, likely due to the occurrence of several road-related landslides the previous year. Although we were not able to measure bedload transport for high energy flows (discharges \u3e 4.5 m3 s−1), we believe our upper estimates for bedload variables (25% of the total sediment load; and a yield of 279 Mg Km−2 y−1) provide reasonable upper bounds. Finally, the bulk of bedload transport is episodic in nature, with a higher proportion moved during high energy tropical storms that occur late in the monsoon rainy season, as well as in response to both natural and anthropogenic landscape disturbances. The possibility that bedload proportion could exceed 20–40% for rivers and streams of various sizes reinforces the need for accurate estimates of both bedload and suspended solid loads prior to building dams in the region. Past examples of reservoir closure following rapid infilling possibly stem from underestimating sediment loads, particularly the bedload component, and failing to factor in the very high sediment loads associated with large storm events