154 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 (ăNOă_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 ăNOă_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 ăNOă_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 ăNOă_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 ăNOă_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 Ăndice de ĂĄrea Foliar (IAF) e biomassa em pastagem no estado de RondĂŽnia, Brasil
Medidas mensais da altura da pastagem, biomassa total, variaçÔes de biomassa viva e morta, a ĂĄrea especĂfica foliar (SLA) e o Ăndice de Ărea 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, RondĂŽnia, Brasil. A pastagem predominante Ă© 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 mĂ©dia anual da grama foi de ~0,16 m. Com o pastejo, o mĂnimo mensal foi de 0,09 m (estação seca) e mĂĄximo de 0,3 m sem pastejo (estação Ășmida). O IAF, biomassa total, material morto, vivo e SLA tiveram valores mĂ©dios de 2,5 m2 m-2 , 2202 kg ha-1, 2916 kg ha-1 e 19 m2 kg-1 respectivamente. A mĂ©dia 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 Ășmida (3229 contra 2529 kg ha-1), sendo o morto maior durante a seca (2542 contra 1894 kg ha-1). O nĂvel de ĂĄgua no solo variou de -3,1 a -6,5 m durante as estaçÔes. Em mĂ©dias 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 observaçÔes 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 = 2.7Ă10-8, HR = 1.14, 95% CI: 1.09-1.20). In addition, we identified two novel ovarian cancer risk modifier loci: 17q21.31 (rs17631303, P = 1.4Ă10-8, HR = 1.27, 95% CI: 1.17-1.38) and 4q32.3 (rs4691139, P = 3.4Ă10-8, 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
Composição corporal e exigĂȘncias lĂquidas de energia e proteĂna de bezerros da raça holandesa alimentados com dietas contendo diferentes nĂveis de volumoso
O objetivo deste trabalho foi avaliar os efeitos de diferentes nĂveis de volumoso nas dietas, sobre a composição corporal, as exigĂȘncias de energia lĂquida para mantença e ganho de peso e os requerimentos lĂquidos de proteĂna para ganho de peso. Cinquenta e dois bezerros da raça Holandesa, puros por cruzamento, nĂŁo-castrados, com idade mĂ©dia de 60 dias e peso vivo (PV) inicial de 78 kg foram usados. Oito animais foram abatidos ao inĂcio do experimento, como referĂȘncia. Outros oito animais foram alimentados com dietas na proporção de 90% de volumoso e 10% de concentrado para atender Ă s exigĂȘncias ligeiramente acima da mantença (grupo de mantença). Os 36 animais restantes foram distribuĂdos nos tratamentos, em delineamento inteiramente casualizado, em quatro grupos de nove animais, de acordo com o nĂvel de volumoso nas dietas: 10, 25, 40 e 55%, na base da MS, usando-se feno de capim coast-cross (Cynodon dactylon), fubĂĄ de milho e farelo de soja, os quais constituĂram dietas com aproximadamente 16% de PB.. Cinco animais de cada tratamento foram abatidos, quando atingiram 190 ± 10 kg PV e quatro, quando atingiram 300 ± 10 kg PV. A exigĂȘncia de energia lĂquida (EL) para mantença foi estimada da equação de regressĂŁo do logaritmo da producĂŁo de calor e em relação ao consumo de energia metabolizĂĄvel (CEM), assumindo CEM igual a zero. EquaçÔes de regressĂŁo foram ajustadas, para cada nĂvel de volumoso e em conjunto, do logaritmo das quantidades corporais de gordura, proteĂna e energia, em função do logaritmo do peso corporal vazio (PCVZ). A exigĂȘncia de energia lĂquida para mantença foi, em mĂ©dia, de 110,46 kcal/kg0,75. A quantidade de gordura e o conteĂșdo de energia no ganho de peso aumentaram, Ă medida que se elevou o PV do animal, para todos os nĂveis de volumoso e em conjunto. As exigĂȘncias lĂquidas de energia e proteĂna para ganho de 1 kg de PCVZ, para um animal de 300 kg de peso vivo, foram 2,83 Mcal/dia e 183,20 g/dia, respectivamente. As exigĂȘncias lĂquidas de energia e proteĂna para ganho de bezerros da raça Holandesa, em mĂ©dia, aumentaram com o aumento do peso corporal vazio
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