336 research outputs found
Continuum theory of vacancy-mediated diffusion
We present and solve a continuum theory of vacancy-mediated diffusion (as
evidenced, for example, in the vacancy driven motion of tracers in crystals).
Results are obtained for all spatial dimensions, and reveal the strongly
non-gaussian nature of the tracer fluctuations. In integer dimensions, our
results are in complete agreement with those from previous exact lattice
calculations. We also extend our model to describe the vacancy-driven
fluctuations of a slaved flux line.Comment: 25 Latex pages, subm. to Physical Review
Outsourcing Governance: States and the Politics of a âGlobal Value Chain Worldâ
Politics, and by extension states, are marginal in debates about the genesis, evolution
and functioning of the GVC-based global economy. We contend here that the core complexity of
state agency and state power needs to be much more carefully understood in GVC and related
debates, as a basis on which the governance of the evolving GVC world can be properly
theorised as revolving around the inseparability of economic and political power. We advance a
framework for understanding the role of politics and states in the construction and maintenance
of a GVC world, using a three-fold typology of facilitative, regulatory and distributive forms of
governance, and propose a notion of âoutsourcing governanceâ as an attempt to capture the
ways in which states purposefully, through active political agency, have engaged in a process of
delegating a variety of governance functions and authority to private actors. Our overarching
argument is normative: âoutsourced governanceâ of the form we currently observe is associated
with regressive distributional outcomes, and is antithetical to an inclusive and sustainable global
economy
Ozone induces glucose intolerance and systemic metabolic effects in young and aged brown Norway rats
Air pollutants have been associated with increased diabetes in humans. We hypothesized that ozone would impair glucose homeostasis by altering insulin signaling and/or endoplasmic reticular (ER) stress in young and aged rats. One, 4, 12, and 24 month old Brown Norway (BN) rats were exposed to air or ozone, 0.25 or 1.0 ppm, 6 h/day for 2 days (acute) or 2 d/week for 13 weeks (subchronic). Additionally, 4 month old rats were exposed to air or 1.0 ppm ozone, 6 h/day for 1 or 2 days (time-course). Glucose tolerance tests (GTT) were performed immediately after exposure. Serum and tissue biomarkers were analyzed 18 h after final ozone for acute and subchronic studies, and immediately after each day of exposure in the time-course study. Age-related glucose intolerance and increases in metabolic biomarkers were apparent at baseline. Acute ozone caused hyperglycemia and glucose intolerance in rats of all ages. Ozone-induced glucose intolerance was reduced in rats exposed for 13 weeks. Acute, but not subchronic ozone increased α2-macroglobulin, adiponectin and osteopontin. Time-course analysis indicated glucose intolerance at days 1 and 2 (2> 1), and a recovery 18 h post ozone. Leptin increased day 1 and epinephrine at all times after ozone. Ozone tended to decrease phosphorylated insulin receptor substrate-1 in liver and adipose tissues. ER stress appeared to be the consequence of ozone induced acute metabolic impairment since transcriptional markers of ER stress increased only after 2 days of ozone. In conclusion, acute ozone exposure induces marked systemic metabolic impairments in BN rats of all ages, likely through sympathetic stimulation
Estimating the global conservation status of more than 15,000 Amazonian tree species
Estimates of extinction risk for Amazonian plant and animal species are rare and not often incorporated into land-use policy and conservation planning. We overlay spatial distribution models with historical and projected deforestation to show that at least 36% and up to 57% of all Amazonian tree species are likely to qualify as globally threatened under International Union for Conservation of Nature (IUCN) Red List criteria. If confirmed, these results would increase the number of threatened plant species on Earth by 22%. We show that the trends observed in Amazonia apply to trees throughout the tropics, and we predict thatmost of the world’s >40,000 tropical tree species now qualify as globally threatened. A gap analysis suggests that existing Amazonian protected areas and indigenous territories will protect viable populations of most threatened species if these areas suffer no further degradation, highlighting the key roles that protected areas, indigenous peoples, and improved governance can play in preventing large-scale extinctions in the tropics in this century
Percepção ambiental dos produtores e qualidade do solo em propriedades orgùnicas e convencionais.
O sistema orgĂąnico de produção deve resultar na utilização mais racional dos recursos naturais, sobretudo do solo. Os produtores orgĂąnicos devem adotar prĂĄticas conservacionistas, alĂ©m de atender a outros princĂpios deste sistema de produção. Neste trabalho foram avaliadas as prĂĄticas de manejo e conservação do solo adotadas por produtores orgĂąnicos e convencionais nas regiĂ”es dos municĂpios de Socorro (Serra da Mantiqueira e Mogiana) e IbiĂșna, situados no Estado de SĂŁo Paulo. O objetivo dessa pesquisa foi verificar o grau de adoção de prĂĄticas conservacionistas pelos produtores e avaliar a qualidade do solo na agricultura orgĂąnica e convencional. Foi elaborado e aplicado um questionĂĄrio, com visitas locais para verificação das prĂĄticas conservacionistas e ocorrĂȘncia de erosĂŁo, em 30 propriedades. Os resultados foram expressos em Ăndices indicadores de diversidade de uso do solo, atitude conservacionista, percepção de erosĂŁo e do impacto sobre os recursos hĂdricos. Foram tambĂ©m realizadas anĂĄlises de atributos quĂmicos, fĂsicos e biolĂłgicos indicadores da qualidade do solo. Concluiu-se que os produtores orgĂąnicos tĂȘm maior percepção quanto Ă atitude conservacionista e nas propriedades orgĂąnicas hĂĄ maior diversidade de cultivos, embora nĂŁo haja maior diversidade geral de uso do solo. A produção orgĂąnica de alface, em IbiĂșna proporcionou maior atividade biolĂłgica no solo e maior colonização por fungos micorrĂzicos arbusculares. O sistema orgĂąnico possui maiores teores de matĂ©ria orgĂąnica e menores de potĂĄssio e nĂŁo houve diferença entre os atributos fĂsicos do solo dos sistemas orgĂąnico e convencional
Pneumococcal Phasevarions Control Multiple Virulence Traits, Including Vaccine Candidate Expression
Published online 10 May 2022Streptococcus pneumoniae is the most common cause of bacterial illness worldwide. Current vaccines based on the polysaccharide capsule are only effective against a limited number of the .100 capsular serotypes. A universal vaccine based on conserved protein antigens requires a thorough understanding of gene expression in S. pneumoniae. All S. pneumoniae strains encode the SpnIII Restriction-Modification system. This system contains a phase-variable methyltransferase that switches specificity, and controls expression of multiple genesâa phasevarion. We examined the role of this phasevarion during pneumococcal pathobiology, and determined if phase variation resulted in differences in expression of currently investigated conserved protein antigens. Using locked strains that express a single methyltransferase specificity, we found differences in clinically relevant traits, including survival in blood, and adherence to and invasion of human cells. We also observed differences in expression of numerous proteinaceous vaccine candidates, which complicates selection of antigens for inclusion in a universal protein-based pneumococcal vaccine. This study will inform vaccine design against S. pneumoniae by ensuring only stably expressed candidates are included in a rationally designed vaccine.Zachary N. Phillips, Claudia Trappetti, Annelies Van Den Bergh, Gael Martin, Ainslie Calcutt, Victoria Ozberk, Patrice Guillon, Manisha Pandey, Mark von Itzstein, W. Edward Swords, James C. Paton, Michael P. Jennings, John M. Atac
Genetics of tension-type headache
The objective of this study was to investigate the importance of genetics in tension-type headache. A MEDLINE search from 1966 to December 2006 was performed for âtension-type headache and prevalenceâ and âtension-type headache and geneticsâ The prevalence of tensiontype headache varies from 11 to 93%, with a slight female preponderance. Co-occurrence of migraine increases the frequency of tension-type headache. A family study of chronic tension-type headache suggests that genetic factors are important. A twin study analysing tension-type headache in migraineurs found that genetic factors play a minor role in episodic tension-type headache. Another twin study analysing twin pairs without co-occurrence of migraine showed a significantly higher concordance rate among monozygotic than same-gender dizygotic twin pairs with no or frequent episodic tension-type headache, while the difference was minor in twin pairs with infrequent episodic tensiontype headache. Frequent episodic and chronic tension-type headache is caused by a combination of genetic and environmental factors, while infrequent episodic tensiontype headache is caused primarily by environmental factors
An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics
For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types
Potential production and environmental effects of switchgrass and traditional crops under current and greenhouse-altered climate in the central United States: a simulation study
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