445 research outputs found

    Iodine monoxide in the north subtropical free troposphere

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    Iodine monoxide (IO) differential slant column densities (DSCD) have been retrieved from a new multi-axis differential optical absorption spectroscopy (MAX-DOAS) instrument deployed at the Iza˜na subtropical observatory as part of the Network for the Detection of Atmospheric Composition Change (NDACC) programme.We acknowledge the support of the European Commission through the GEOmon (Global Earth Observation and Monitoring) Integrated Project under the 6th Framework Program (contract number FP6-2005-Global-4-036677) and NORS (Demonstration Network Of ground-based Remote Sensing Observations in support of the GMES Atmospheric Service) Integrated Project under the 7th Framework Program (contract number FP7-SPACE- 2011-284421)

    IR and UV Galaxies at z=0.6 -- Evolution of Dust Attenuation and Stellar Mass as Revealed by SWIRE and GALEX

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    We study dust attenuation and stellar mass of z0.6\rm z\sim 0.6 star-forming galaxies using new SWIRE observations in IR and GALEX observations in UV. Two samples are selected from the SWIRE and GALEX source catalogs in the SWIRE/GALEX field ELAIS-N1-00 (Ω=0.8\Omega = 0.8 deg2^2). The UV selected sample has 600 galaxies with photometric redshift (hereafter photo-z) 0.5z0.70.5 \leq z \leq 0.7 and NUV23.5\leq 23.5 (corresponding to \rm L_{FUV} \geq 10^{9.6} L_\sun). The IR selected sample contains 430 galaxies with f24μm0.2f_{24\mu m} \geq 0.2 mJy (\rm L_{dust} \geq 10^{10.8} L_\sun) in the same photo-z range. It is found that the mean Ldust/LFUV\rm L_{dust}/L_{FUV} ratios of the z=0.6 UV galaxies are consistent with that of their z=0 counterparts of the same LFUV\rm L_{FUV}. For IR galaxies, the mean Ldust/LFUV\rm L_{dust}/L_{FUV} ratios of the z=0.6 LIRGs (\rm L_{dust} \sim 10^{11} L_\sun) are about a factor of 2 lower than local LIRGs, whereas z=0.6 ULIRGs (\rm L_{dust} \sim 10^{12} L_\sun) have the same mean Ldust/LFUV\rm L_{dust}/L_{FUV} ratios as their local counterparts. This is consistent with the hypothesis that the dominant component of LIRG population has changed from large, gas rich spirals at z>0.5>0.5 to major-mergers at z=0. The stellar mass of z=0.6 UV galaxies of \rm L_{FUV} \leq 10^{10.2} L_\sun is about a factor 2 less than their local counterparts of the same luminosity, indicating growth of these galaxies. The mass of z=0.6 UV lunmous galaxies (UVLGs: \rm L_{FUV} > 10^{10.2} L_\sun) and IR selected galaxies, which are nearly exclusively LIRGs and ULIRGs, is the same as their local counterparts.Comment: 27 pages, 8 figures, to be published in the Astrophysical Journal Supplement series dedicated to GALEX result

    Reconstructions of biomass burning from sediment charcoal records to improve data-model comparisons

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    The location, timing, spatial extent, and frequency of wildfires are changing rapidly in many parts of the world, producing substantial impacts on ecosystems, people, and potentially climate. Paleofire records based on charcoal accumulation in sediments enable modern changes in biomass burning to be considered in their long-term context. Paleofire records also provide insights into the causes and impacts of past wildfires and emissions when analyzed in conjunction with other paleoenvironmental data and with fire models. Here we present new 1000 year and 22 000 year trends and gridded biomass burning reconstructions based on the Global Charcoal Database version 3, which includes 736 charcoal records (57 more than in version 2). The new gridded reconstructions reveal the spatial patterns underlying the temporal trends in the data, allowing insights into likely controls on biomass burning at regional to global scales. In the most recent few decades, biomass burning has sharply increased in both hemispheres, but especially in the north, where charcoal fluxes are now higher than at any other time during the past 22 000 {years}. We also discuss methodological issues relevant to data-model comparisons, and identify areas for future research. Spatially gridded versions of the global dataset from GCDv3 are provided to facilitate comparison with and validation of global fire simulations

    Profiles in Community-Engaged Learning

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    To provide a snapshot of the many impressive manifestations of community-engaged learning at the University of San Francisco, a 2014-2015 Faculty Learning Community (FLC), supported by the Center for Teaching Excellence (CTE), has collected the following profiles of selected faculty members across all the schools and colleges. This report was prepared by members of the CTE’s Faculty Learning Community on Community-Engaged Learning: Kevin D. Lo, Facilitator (School of Management), Emma Fuentes (School of Education), David Holler (College of Arts and Sciences), Tim Iglesias (School of Law), Susan Roberta Katz (School of Education), Star Moore (Leo T. McCarthy Center for Public Service and the Common Good), Chenit Ong-Flaherty (School of Nursing and Health Professions), Jennifer Parlamis (School of Management) Susan Pauly-O’Neill (School of Nursing and Health Professions). Our intent with this report is to offer USF administrators and incoming faculty members a sense of what’s being done well in community-engaged learning (CEL), while also pointing out what challenges remain as we establish our identity as a university that prioritizes community engagement. (Incidentally, we prefer the term “community-engaged learning” to “service-learning,” which we feel more precisely defines the scope of our activities. For more about this designation, please see the Executive Report on Community Engaged Learning issued by this same committee in June 2015.) Community-engaged learning as defined by Eyler and Giles is “a form of experiential education where learning occurs through a cycle of action and reflection as students . . . seek to achieve real objectives for the community and deeper understanding and skills for themselves. In the process, students link personal and social development with academic and cognitive development . . . experience enhances understanding; understanding leads to more effective action.” (qtd. in Bandy, Vanderbilt Center for Teaching, “What Is Service Learning or Community Engagement?”). We invited at least two faculty members from each school/college to answer several questions about the application of CEL in their courses. After providing a brief overview of activities in each course, we asked each professor what works well and what challenges persist. The successes and the challenges, as you’ll see, vary widely, and yet they clearly delineate, limited though our present sample size is, the great variety and energy and commitment our faculty have demonstrated in working with community partners and students. It is our hope that this report is merely the beginning of a much more ambitious project to be taken up by the McCarthy Center which will provide many more profiles of professors in the months and years to come

    Modulation of enhancer looping and differential gene targeting by Epstein-Barr virus transcription factors directs cellular reprogramming

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    Epstein-Barr virus (EBV) epigenetically reprogrammes B-lymphocytes to drive immortalization and facilitate viral persistence. Host-cell transcription is perturbed principally through the actions of EBV EBNA 2, 3A, 3B and 3C, with cellular genes deregulated by specific combinations of these EBNAs through unknown mechanisms. Comparing human genome binding by these viral transcription factors, we discovered that 25% of binding sites were shared by EBNA 2 and the EBNA 3s and were located predominantly in enhancers. Moreover, 80% of potential EBNA 3A, 3B or 3C target genes were also targeted by EBNA 2, implicating extensive interplay between EBNA 2 and 3 proteins in cellular reprogramming. Investigating shared enhancer sites neighbouring two new targets (WEE1 and CTBP2) we discovered that EBNA 3 proteins repress transcription by modulating enhancer-promoter loop formation to establish repressive chromatin hubs or prevent assembly of active hubs. Re-ChIP analysis revealed that EBNA 2 and 3 proteins do not bind simultaneously at shared sites but compete for binding thereby modulating enhancer-promoter interactions. At an EBNA 3-only intergenic enhancer site between ADAM28 and ADAMDEC1 EBNA 3C was also able to independently direct epigenetic repression of both genes through enhancer-promoter looping. Significantly, studying shared or unique EBNA 3 binding sites at WEE1, CTBP2, ITGAL (LFA-1 alpha chain), BCL2L11 (Bim) and the ADAMs, we also discovered that different sets of EBNA 3 proteins bind regulatory elements in a gene and cell-type specific manner. Binding profiles correlated with the effects of individual EBNA 3 proteins on the expression of these genes, providing a molecular basis for the targeting of different sets of cellular genes by the EBNA 3s. Our results therefore highlight the influence of the genomic and cellular context in determining the specificity of gene deregulation by EBV and provide a paradigm for host-cell reprogramming through modulation of enhancer-promoter interactions by viral transcription factors

    Nox2-deficient Tregs improve heart transplant outcomes via their increased graft recruitment and enhanced potency.

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    Nox2 is a ROS-generating enzyme, deficiency of which increases suppression by Tregs in vitro and in an in vivo model of cardiac remodelling. Since Tregs have emerged as a candidate therapy in autoimmunity and transplantation, we hypothesised that Nox2 deficiency in Tregs in recipient mice may improve outcomes in a heart transplant model. A novel B6129 mouse model with Treg-targeted Nox2 deletion (Nox2fl/flFoxP3Cre+) was generated and transplanted with hearts from CB6F1 donors. As compared to littermate controls, Nox2fl/flFoxP3Cre+ mice had lower plasma levels of alloantibodies and troponin-I, reduced levels of IFN-γ in heart allograft homogenates and diminished cardiomyocyte necrosis and allograft fibrosis. Single cell analyses of allografts revealed higher absolute numbers of Tregs and lower CD8+ T cell infiltration in Nox2-deficient recipients compared to Nox2-replete mice. Mechanistically, in addition to a greater suppression of CD8+CD25- T effector cell proliferation and IFN-γ production, Nox2-deficient Tregs expressed higher levels of CCR4 and CCR8, driving cell migration to allografts; this was associated with increased expression of miR214-3p. These data indicate that Nox2 deletion in Tregs enhances their suppressive ability and migration to heart allografts. Therefore, Nox2 inhibition in Tregs may be a useful approach to improve their therapeutic efficacy
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