Vibrational modes of circular free plates under tension

The vibrational frequencies of a plate under tension are given by the eigenvalues $\omega$ of the equation $\Delta^2u-\tau\Delta u=\omega u$. This paper determines the eigenfunctions and eigenvalues of this bi-Laplace problem on the ball under natural (free) boundary conditions. In particular, the fundamental modes --- the eigenfunctions of the lowest nonzero eigenvalue --- are identified and found to have simple angular dependence.Comment: 17 pages. To be submitted for publication shortly

Linking ecology to genetics to better understand adaptation and evolution: a review in marine macrophytes

Ecological processes and intra-specific genetic diversity reciprocally affect each other. While the importance of uniting ecological variables and genetic variation to understand species’ plasticity, adaptation, and evolution is increasingly recognized, only few studies have attempted to address the intersection of population ecology and genetics using marine macrophyte as models. Representative empirical case studies on genetic diversity are reviewed that explore ecological and evolutionary processes in marine macrophytes. These include studies on environment-induced phenotypic plasticity and associated ecological adaptation; population genetic variation and structuring driven by ecological variation; and ecological consequences mediated by intraspecific and interspecific diversity. Knowledge gaps are also discussed that impede the connection of ecology and genetics in macrophytes and possible approaches to address these issues. Finally, an eco-evolutionary perspective is advocated, by incorporating structural-tofunctional genomics and life cycle complexity, to increase the understanding of the adaptation and evolution of macrophytes in response to environmental heterogeneity.info:eu-repo/semantics/publishedVersio

Infection of the brown alga Ectocarpus siliculosus by the oomycete Eurychasma dicksonii induces oxidative stress and halogen metabolism

Acknowledgments We would like to thank the Aberdeen Proteome Facility, especially Phil Cash, David Stead and Evelyn Argo for assistance with 2D electrophoresis and mass spectrometry. M.S. gratefully acknowledges a Marie Curie PhD fellowship from the European Commission (ECOSUMMER, MEST-CT-2005-20501), a joint FEMS/ESCMID Research Fellowship and the Genomia Fund. C.M.M.G. is supported by a Marie Curie postdoctoral fellowship (MEIF-CT-2006-022837), a Marie Curie Re-Integration Grant (PERG03-GA-2008-230865) and a New Investigator grant from the UK Natural Environment Research Council (NERC, grant NE/J00460X/1). F.C.K. would like to thank NERC for funding (grants NE/D521522/1, NE/F012705/1 and Oceans 2025 / WP 4.5). L.J.G.-B., C.M.M.G., F.C.K. and P.W. would like to acknowledge funding from NERC for a Strategic Ocean Funding Initiative award (NE/F012578/1). Funding from the MASTS pooling initiative (Marine Alliance for Science and Technology for Scotland, funded by the Scottish Funding Council and contributing institutions; grant reference HR09011) and from the TOTAL Foundation (Paris) to F.C.K. is gratefully acknowledged. Finally, we would like to thank the two anonymous referees for constructive suggestions to improve our manuscript.Peer reviewedPublisher PD

Outbreak of West Nile virus causing severe neurological involvement in children, Nuba Mountains, Sudan, 2002.

An atypical outbreak of West Nile virus (WNV) occurred in Ngorban County, South Kordophan, Sudan, from May to August 2002. We investigated the epidemic and conducted a case-control study in the village of Limon. Blood samples were obtained for cases and controls. Patients with obvious sequelae underwent cerebrospinal fluid (CSF) sampling as well. We used enzyme-linked immunosorbent assay (ELISA) and neutralization tests for laboratory diagnosis and identified 31 cases with encephalitis, four of whom died. Median age was 36 months. Bivariate analysis did not reveal any significant association with the risk factors investigated. Laboratory analysis confirmed presence of IgM antibodies caused by WNV in eight of 13 cases, indicative of recent viral infection. The unique aspects of the WNW outbreak in Sudan, i.e. disease occurrence solely among children and the clinical domination of encephalitis, involving severe neurological sequelae, demonstrate the continuing evolution of WNV virulence. The spread of such a virus to other countries or continents cannot be excluded

Highly photoluminescent copper carbene complexes based on prompt rather than delayed fluorescence

Linear two-coordinate copper complexes of cyclic (alkyl)(amino)-carbenes (CAAC)CuX (X = halide) show photoluminescence with solid-state quantum yields of up to 96%; in contrast to previously reported Cu photoemitters the emission is independent of temperature over the range T = 4 – 300 K and occurs very efficiently by prompt rather than delayed fluorescence, with lifetimes in the sub-nanosecond range

MtDNA-Based Phylogeography of the Red Alga Agarophyton vermiculophyllum (Gigartinales, Rhodophyta) in the Native Northwest Pacific

The repeated transgression and regression of coastlines mediated by the late Quaternary glacial–interglacial cycles make the northwest Pacific a hot spot to study marine speciation and population diversity. The red alga Agarophyton vermiculophyllum is an ecologically important species native to the northwest Pacific, capturing considerable research interest due to its wide-range invasiveness in Europe and North America. However, the knowledge of phylogeographic structure and intraspecific genetic diversity across the entire native range was still scarce. Here, we used 1,214-bp of mitochondrial cytochrome c oxidase subunit 1 (cox1) to explore phylogeographic patterns, lineage structure, and population genetic differentiation of 48 A. vermiculophyllum populations in the northwest Pacific. Our DNA data revealed overall high haplotype diversity and low nucleotide diversity and five phylogeographically structured genetic lineages that diverged significantly from each other. S-DIVA analysis showed the ancestors of A. vermiculophyllum originating from multiple areas encompassing the Japan–Pacific coast, East and South China Seas. This combined evidence indicates that A. vermiculophyllum might have survived in multiple scattered glacial refugia during the late Quaternary climate oscillations in the northwest Pacific. Such knowledge may help to better understand how palaeoclimate interacted with contemporary environments to contribute to intraspecific genetic variation and provide a new perspective for conserving natural resource of A. vermiculophyllum in the northwest Pacific

Spatially resolved H2 emission from the disk around T Tau N

We report the detection of quiescent H2 emission in a spatially resolved ring-like structure within 100 AU of T Tau N. We present evidence to show that the emission most likely arises from shocks in the atmosphere of a nearly face-on disk around T Tau N. Using high spatial resolution 3D spectroscopic K-band data, we trace the spatial distribution of several H2 NIR rovibrational lines in the vicinity of T Tau N. We detect weak H2 emission from the v=1-0 S(0), S(1), Q(1) lines and the v=2-1 S(1) line in a ring-like structure around T Tau N between 0.1'' (~15 AU) and 0.7'' (~100AU) from the star. The v=1-0 S(0) and v=2-1 S(1) lines are detected only in the outer parts of the ring structure. Closer to the star, the strong continuum limits our sensitivity to these lines. The total flux of the v=1-0 S(1) line is 1.8 *10^{-14} ergs s^{-1}cm^{-2}, similar to previous measurements of H2 in circumstellar disks. The velocity of the H2 emitting gas around T Tau N is consistent with the rest velocity of the star, and the H2 does not seem to be part of a collimated outflow. Both shocks impinging on the surface of a disk and irradiation of a disk by UV-photons and X-rays from the central star are plausible candidates for the H2 excitation mechanism. However, irradiation should not create a large degree of excitation at radii larger than 20 AU. Most likely the H2 emission arises in the atmosphere of a flared disk with radius 85-100 AU and mass 0.005-0.5Msun, where the gas is excited by shocks created when a wide-angle wind impinges on the disk. The H2 emission could also originate from shock excitation in the cavity walls of an envelope, but this requires an unusually high velocity of the wide-angle wind from T Tau N.Comment: Accepted by A&

Modeling neurocognitive and neurobiological recovery in addiction

This book focuses on "what to know" and "how to apply" information, prioritizing novel principles and delineating cutting-edge assessment, phenotyping and treatment tools

A reference map of potential determinants for the human serum metabolome

The serum metabolome contains a plethora of biomarkers and causative agents of various diseases, some of which are endogenously produced and some that have been taken up from the environment(1). The origins of specific compounds are known, including metabolites that are highly heritable(2,3), or those that are influenced by the gut microbiome(4), by lifestyle choices such as smoking(5), or by diet(6). However, the key determinants of most metabolites are still poorly understood. Here we measured the levels of 1,251 metabolites in serum samples from a unique and deeply phenotyped healthy human cohort of 491 individuals. We applied machine-learning algorithms to predict metabolite levels in held-out individuals on the basis of host genetics, gut microbiome, clinical parameters, diet, lifestyle and anthropometric measurements, and obtained statistically significant predictions for more than 76% of the profiled metabolites. Diet and microbiome had the strongest predictive power, and each explained hundreds of metabolites-in some cases, explaining more than 50% of the observed variance. We further validated microbiome-related predictions by showing a high replication rate in two geographically independent cohorts(7,8) that were not available to us when we trained the algorithms. We used feature attribution analysis(9) to reveal specific dietary and bacterial interactions. We further demonstrate that some of these interactions might be causal, as some metabolites that we predicted to be positively associated with bread were found to increase after a randomized clinical trial of bread intervention. Overall, our results reveal potential determinants of more than 800 metabolites, paving the way towards a mechanistic understanding of alterations in metabolites under different conditions and to designing interventions for manipulating the levels of circulating metabolites.The levels of 1,251 metabolites are measured in 475 phenotyped individuals, and machine-learning algorithms reveal that diet and the microbiome are the determinants with the strongest predictive power for the levels of these metabolites