152 research outputs found
Monopoles and clusters
We define and study certain hyperkaehler manifolds which capture the
asymptotic behaviour of the SU(2)-monopole metric in regions where monopoles
break down into monopoles of lower charges. The rate at which these new metrics
approximate the monopole metric is exponential, as for the Gibbons-Manton
metric.Comment: v2.: relation to calorons mentioned; added explanation
Dietary nitrate does not have an effect on physical activity outcomes in healthy older adults : a randomized, cross-over trial
Dietary nitrate (〖NO〗_3^-) ingestion appears to enhance exercise capacity and performance in young individuals whereas inconclusive findings have been reported in older people. We conducted a double-blind, cross-over randomized clinical trial in older normal weight and overweight healthy participants testing whether beetroot juice (a rich source of 〖NO〗_3^-) for one week may increase nitric oxide bioavailability via the non-enzymatic pathway and enhance 1) exercise capacity during an incremental exercise test, 2) physical capability and 3) free-living physical activity.
Twenty non-smoking healthy participants aged 60-75y and BMI 20.0-29.9kg/m2 were included. Pre and post supplementation resting, sub-maximal, maximal and recovery gas exchanges were measured. Physical capability was measured by hand-grip strength (HGS), time-up-and-go (TUG), repeated-chair-rising-test (RCRT), and 10m walking speed (WLS). Free-living physical activity was assessed by triaxal accelerometry. Changes in urinary and plasma 〖NO〗_3^- concentrations were measured by gas chromatography mass spectrometry.
Nineteen participants (M/F=9/10) completed the study. Beetroot juice increased significantly both plasma and urinary 〖NO〗_3^- concentrations (p<0.001) compared to placebo. Beetroot juice did not influence resting, sub-maximal and maximal oxygen consumption during the incremental exercise test. In addition, measures of physical capability and physical activity levels measured in free-living conditions were not modified by beetroot juice ingestion.
The positive effects of beetroot juice ingestion on exercise performance seen in young individuals were not replicated in healthy, older adults. Whether aging represents a modifier of the effects of dietary 〖NO〗_3^- on muscular performance is not known and mechanistic studies and larger trials are needed to test this hypothesis.
Keywords: inorganic nitrate, nitric oxide, exercise, oxygen consumption, agin
Estimativa do índice de área Foliar (IAF) e biomassa em pastagem no estado de Rondônia, Brasil
Medidas mensais da altura da pastagem, biomassa total, variações de biomassa viva e morta, a área específica foliar (SLA) e o Índice de Área de Folha (IAF) de fevereiro de 1999 a janeiro de 2005 na Fazenda Nossa Senhora (FNS) e em Rolim de Moura (RDM) entre Fevereiro a Março de 1999, Rondônia, Brasil. A pastagem predominante é Urochloa brizantha (Hochst. ex A. Rich) R. D. Webster (99% na FNS e 76% em RDM), com pequenas manchas de Urochloa humidicula (Rendle). A altura média anual da grama foi de ~0,16 m. Com o pastejo, o mínimo mensal foi de 0,09 m (estação seca) e máximo de 0,3 m sem pastejo (estação úmida). O IAF, biomassa total, material morto, vivo e SLA tiveram valores médios de 2,5 m2 m-2 , 2202 kg ha-1, 2916 kg ha-1 e 19 m2 kg-1 respectivamente. A média mensal da biomassa foi 4224 kg ha-1 em 2002 e 6667 kg ha-1 em 2003. Grande variação sazonal do material vivo e morto, sendo mais alto o vivo durante a estação úmida (3229 contra 2529 kg ha-1), sendo o morto maior durante a seca (2542 contra 1894 kg ha-1). O nível de água no solo variou de -3,1 a -6,5 m durante as estações. Em médias anuais os IAF foram de 1,4 em 2000 a 2,8 em 2003 e o SLA entre 16,3 m2 kg-1 em 1999 e 20,4 m2 kg-1 em 2001. As observações do Albedo variaram de 0,18 para 0,16 em relação aos altos valores de IAF
MeMoVolc report on classification and dynamics of volcanic explosive eruptions
Classifications of volcanic eruptions were first introduced in the early twentieth century mostly based on qualitative observations of eruptive activity, and over time, they have gradually been developed to incorporate more quantitative descriptions of the eruptive products from both deposits and observations of active volcanoes. Progress in physical volcanology, and increased capability in monitoring, measuring and modelling of explosive eruptions, has highlighted shortcomings in the way we classify eruptions and triggered a debate around the need for eruption classification and the advantages and disadvantages of existing classification schemes. Here, we (i) review and assess existing classification schemes, focussing on subaerial eruptions; (ii) summarize the fundamental processes that drive and parameters that characterize explosive volcanism; (iii) identify and prioritize the main research that will improve the understanding, characterization and classification of volcanic eruptions and (iv) provide a roadmap for producing a rational and comprehensive classification scheme. In particular, classification schemes need to be objective-driven and simple enough to permit scientific exchange and promote transfer of knowledge beyond the scientific community. Schemes should be comprehensive and encompass a variety of products, eruptive styles and processes, including for example, lava flows, pyroclastic density currents, gas emissions and cinder cone or caldera formation. Open questions, processes and parameters that need to be addressed and better characterized in order to develop more comprehensive classification schemes and to advance our understanding of volcanic eruptions include conduit processes and dynamics, abrupt transitions in eruption regime, unsteadiness, eruption energy and energy balance
Genome-Wide Association Study in BRCA1 Mutation Carriers Identifies Novel Loci Associated with Breast and Ovarian Cancer Risk
BRCA1-associated breast and ovarian cancer risks can be modified by common genetic variants. To identify further cancer risk-modifying loci, we performed a multi-stage GWAS of 11,705 BRCA1 carriers (of whom 5,920 were diagnosed with breast and 1,839 were diagnosed with ovarian cancer), with a further replication in an additional sample of 2,646 BRCA1 carriers. We identified a novel breast cancer risk modifier locus at 1q32 for BRCA1 carriers (rs2290854, P = 2.7×10-8, HR = 1.14, 95% CI: 1.09-1.20). In addition, we identified two novel ovarian cancer risk modifier loci: 17q21.31 (rs17631303, P = 1.4×10-8, HR = 1.27, 95% CI: 1.17-1.38) and 4q32.3 (rs4691139, P = 3.4×10-8, HR = 1.20, 95% CI: 1.17-1.38). The 4q32.3 locus was not associated with ovarian cancer risk in the general population or BRCA2 carriers, suggesting a BRCA1-specific associat
Propriedades físicas e químicas do solo em áreas com sistemas produtivos e mata na região da Zona da Mata mineira
Historical land-cover/use in different slope and riparian buffer zones in watersheds of the state of São Paulo, Brazil
Composição corporal e exigências líquidas de energia e proteína de bezerros da raça holandesa alimentados com dietas contendo diferentes níveis de volumoso
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