Editorial: Sex and Gender Differences in Body Image

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Strategic scarcity: The origins and impact of environmental conflict ideas.

This thesis examines the origins and impact of environmental conflict ideas. It focuses on the work of Canadian political scientist Thomas Homer-Dixon, whose model of environmental conflict achieved considerable prominence in U.S. foreign policy circles in the 1990s. The thesis argues that this success was due in part to widely shared neo-Malthusian assumptions about the Third World, and to the support of private foundations and policymakers with a strategic interest in promoting these views. It analyzes how population control became an important feature of American foreign policy and environmentalism in the post-World War Two period. It then describes the role of the "degradation narrative" -- the belief that population pressures and poverty precipitate environmental degradation, migration, and violent conflict -- in the development of the environment and security field. Based on archival research and interviews with key policymakers, foundation officers, and scholars, the thesis identifies a process of "circumscribed heterodoxy" in which an illusion of openness to diverse views masks a politics of uniformity at both the project and policy level. It examines the intentional and unintentional effects of environmental conflict ideas on U.S. policy institutions, and considers the nature of the knowledge communities that formed around these ideas. In so doing, the thesis offers insights into the complex relationships between knowledge, power, and policy

Expression of vascular endothelial growth factor and pigment epithelial-derived factor in a rat model of retinopathy of prematurity

Objective: To determine the effects of oxygen fluctuations on pigment epithelial-derived factor (PEDF) and vascular endothelial growth factor (VEGF)/PEDF ratios in a relevant rat model of retinopathy of prematurity (ROP)

Cryo-EM structure of the monomeric Rhodobacter sphaeroides RC-LH1 core complex at 2.5 Å.

Reaction centre light-harvesting 1 (RC-LH1) complexes are the essential components of bacterial photosynthesis. The membrane-intrinsic LH1 complex absorbs light and the energy migrates to an enclosed RC where a succession of electron and proton transfers conserves the energy as a quinol, which is exported to the cytochrome bc1 complex. In some RC-LH1 variants quinols can diffuse through small pores in a fully circular, 16-subunit LH1 ring, while in others missing LH1 subunits create a gap for quinol export. We used cryogenic electron microscopy to obtain a 2.5 Å resolution structure of one such RC-LH1, a monomeric complex from Rhodobacter sphaeroides. The structure shows that the RC is partly enclosed by a 14-subunit LH1 ring in which each αβ heterodimer binds two bacteriochlorophylls and, unusually for currently reported complexes, two carotenoids rather than one. Although the extra carotenoids confer an advantage in terms of photoprotection and light harvesting, they could impede passage of quinones through small, transient pores in the LH1 ring, necessitating a mechanism to create a dedicated quinone channel. The structure shows that two transmembrane proteins play a part in stabilising an open ring structure; one of these components, the PufX polypeptide, is augmented by a hitherto undescribed protein subunit we designate as protein-Y, which lies against the transmembrane regions of the thirteenth and fourteenth LH1α polypeptides. Protein-Y prevents LH1 subunits 11-14 adjacent to the RC QB site from bending inwards towards the RC and, with PufX preventing complete encirclement of the RC, this pair of polypeptides ensures unhindered quinone diffusion

Supermassive black holes at high redshifts

MeV blazars are the most luminous persistent sources in the Universe and emit most of their energy in the MeV band. These objects display very large jet powers and accretion luminosities and are known to host black holes with a mass often exceeding $10^9 M_{\odot}$. An MeV survey, performed by a new generation MeV telescope which will bridge the entire energy and sensitivity gap between the current generation of hard X-ray and gamma-ray instruments, will detect $>$1000 MeV blazars up to a redshift of $z=5-6$. Here we show that this would allow us: 1) to probe the formation and growth mechanisms of supermassive black holes at high redshifts, 2) to pinpoint the location of the emission region in powerful blazars, 3) to determine how accretion and black hole spin interplay to power the jet.Comment: 7 pages, 4 figure. Submitted to the Astro2020 call for Science White Paper

Contrasting patterns of functional diversity in coffee root fungal communities associated with organic and conventionally managed fields

The structure and function of fungal communities in the coffee rhizosphere are influenced by crop environment. Because coffee can be grown along a management continuum from conventional application of pesticides and fertilizers in full sun to organic management in a shaded understory, we used coffee fields to hold host constant while comparing rhizosphere fungal communities under markedly different environmental conditions with regard to shade and inputs. We characterized the shade and soil environment in 25 fields under conventional, organic, or transitional management in two regions of Costa Rica. We amplified the internal transcribed spacer 2 (ITS2) region of fungal DNA from coffee roots in these fields and characterized the rhizosphere fungal community via high-throughput sequencing. Sequences were assigned to guilds to determine differences in functional diversity and trophic structure among coffee field environments. Organic fields had more shade, a greater richness of shade tree species, and more leaf litter and were less acidic, with lower soil nitrate availability and higher soil copper, calcium, and magnesium availability than conventionally managed fields, although differences between organic and conventionally managed fields in shade and calcium and magnesium availability depended on region. Differences in richness and community composition of rhizosphere fungi between organic and conventionally managed fields were also correlated with shade, soil acidity, and nitrate and copper availability. Trophic structure differed with coffee field management. Saprotrophs, plant pathogens, and mycoparasites were more diverse, and plant pathogens were more abundant, in organic than in conventionally managed fields, while saprotroph-plant pathogens were more abundant in conventionally managed fields. These differences reflected environmental differences and depended on region

Kenyan milk consumers’ behaviour and perceptions of aflatoxin

Aflatoxin contamination in food is a human health threat in many developing countries. This study examines Kenyan milk consumers’ behaviour related to, and perception of, aflatoxin contamination. The study considered two groups of respondents: raw milk consumers mainly located in peri-urban areas of Nairobi, and processed milk consumers located in urban areas. Results indicate that practically all raw milk consumers and the majority of processed milk consumers boil the milk before its consumption believing that the product is completely safe after boiling. Aflatoxin awareness is very high for the urban milk consumers and relatively high for the peri-urban ones. In both groups, almost half of the respondents who had heard about aflatoxin believe, or know, that it can be transferred into milk. Most respondents, however, did not know how to avoid aflatoxin-contaminated milk. Given the credence characteristic of aflatoxin consumer education and awareness raising programs alone will not be able to solve the problem. Efforts along the whole value chain and at the level of government are needed to reduce the use of aflatoxin spoiled feed and secure aflatoxin safe milk at the consumer level