214 research outputs found

    Comparison of Aquatic-Insect Habitat and Diversity Above and Below Road Crossings in Low-Order Streams

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    The effects of road crossings on fish communities have been extensively studied; yet little attention has been given to macroinvertebrate communities. This study evaluated physical stream characteristics, water quality, and aquatic-insect richness from above and below road crossings of low-order streams in the Ouachita National Forest in Arkansas. Fifteen road crossings were sampled during October and November 2005. Erosion was significantly higher below road crossings than above. Sites downstream of road crossings had significantly lower pH and significantly higher turbidity than sites upstream of road crossings. Despite differences in water quality and habitat, there was no apparent difference in aquatic-insect richness from above and below road crossings based on the EPT index, suggesting that road crossings did not act as barriers to insect movement. The water-quality differences observed were well within acceptable limits and likely not biologically important

    Measurements of charmed-meson production in interactions between 350 GeV/c π\pi^- particles and nuclei

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    Charmed-meson production by 350350~GeV/cc {π\pi^-} particles incident on copper and tungsten targets has been studied in the WA9292 experiment, performed at the CERN Ω\Omega^\prime spectrometer. Results obtained are reported and discussed. Reconstruction of decays from the set D0Kπ+{\rm D}^0 \rightarrow {\rm K}^- \pi^+, D0Kππ+π+{\rm D}^0 \rightarrow {\rm K}^- \pi^- \pi^+ \pi^+, D+Kπ+π+{\rm D}^+ \rightarrow {\rm K}^- \pi^+ \pi^+, Ds+ϕπ+{{\rm D}_{\rm s}}^+ \rightarrow \phi \pi^+ and charge conjugates has yielded a sample of 7280±1087280 \pm 108 charmed mesons, produced with \xf > 0, \langle \xf \rangle = 0.18 and \langle {\pt}^2 \rangle = 1.86~{\rm (GeV/}c{\rm )}^2. Assuming a relationship σ=σ0Aα\sigma = \sigma_0 A^\alpha between the cross-section, σ\sigma, per nucleus of mass AA and the nucleonic cross-section, σ0\sigma_0, the α\alpha value found for the detected charmed particles is 0.95±0.06±0.030.95 \pm 0.06 \pm 0.03. Taking α=1\alpha = 1, the measured cross-sections per nucleon for \xf > 0 production are 7.78±0.14±0.527.78 \pm 0.14 \pm 0.52~μ\mubarn for D0{\rm D}^0/Dˉ0\bar{\rm D}^0, 3.28±0.08±0.293.28 \pm 0.08 \pm 0.29~μ\mubarn for D+{\rm D}^+/D{\rm D}^- and 1.29±0.16±0.331.29 \pm 0.16 \pm 0.33~μ\mubarn for Ds+{{\rm D}_{\rm s}}^+/Ds{{\rm D}_{\rm s}}^-. Differential cross-sections with respect to \xf and {\pt}^2 have been determined for the various types of charmed meson, and particle-antiparticle asymmetries have been analysed

    RT-PCR assays for seven serotypes of epizootic haemorrhagic disease virus & their use to type strains from the Mediterranean region and North America

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    Epizootic haemorrhagic disease virus (EHDV) infects wild ruminants, causing a frequently fatal haemorrhagic disease. However, it can also cause bluetongue-like disease in cattle, involving significant levels of morbidity and mortality, highlighting a need for more rapid and reliable diagnostic assays. EHDV outer-capsid protein VP2 (encoded by genome-segment 2 [Seg-2]) is highly variable and represents the primary target for neutralising antibodies generated by the mammalian host. Consequently VP2 is also the primary determinant of virus “serotype”, as identified in virus neutralisation tests (VNT). Although previous reports have indicated eight to ten EHDV serotypes, recent serological comparisons and molecular analyses of Seg-2 indicate only seven EHDV “types”. Oligonucleotide primers were developed targeting Seg-2, for use in conventional RT-PCR assays to detect and identify these seven types. These assays, which are more rapid and sensitive, still show complete agreement with VNT and were used to identify recent EHDV isolates from the Mediterranean region and North America

    Vapochromic Behaviour of M[Au(CN)2]2-Based Coordination Polymers (M = Co, Ni)

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    A series of M[Au(CN)2]2(analyte)x coordination polymers (M = Co, Ni; analyte = dimethylsulfoxide (DMSO), N,N-dimethylformamide (DMF), pyridine; x = 2 or 4) was prepared and characterized. Addition of analyte vapours to solid M(μ-OH2)[Au(CN)2]2 yielded visible vapochromic responses for M = Co but not M = Ni; the IR νCN spectral region changed in every case. A single crystal structure of Zn[Au(CN)2]2(DMSO)2 revealed a corrugated 2-D layer structure with cis-DMSO units. Reacting a Ni(II) salt and K[Au(CN)2] in DMSO yielded the isostructural Ni[Au(CN)2]2(DMSO)2 product. Co[Au(CN)2]2(DMSO)2 and M[Au(CN)2]2(DMF)2 (M = Co, Ni) complexes have flat 2-D square-grid layer structures with trans-bound DMSO or DMF units; they are formed via vapour absorption by solid M(μ-OH2)[Au(CN)2]2 and from DMSO or DMF solution synthesis. Co[Au(CN)2]2(pyridine)4 is generated via vapour absorption by Co(μ-OH2)[Au(CN)2]2; the analogous Ni complex is synthesized by immersion of Ni(μ-OH2)[Au(CN)2]2 in 4% aqueous pyridine. Similar immersion of Co(μ-OH2)[Au(CN)2]2 yielded Co[Au(CN)2]2(pyridine)2, which has a flat 2-D square-grid structure with trans-pyridine units. Absorption of pyridine vapour by solid Ni(μ-OH2)[Au(CN)2]2 was incomplete, generating a mixture of pyridine-bound complexes. Analyte-free Co[Au(CN)2]2 was prepared by dehydration of Co(μ-OH2)[Au(CN)2]2 at 145 °C; it has a 3-D diamondoid-type structure and absorbs DMSO, DMF and pyridine to give the same materials as by vapour absorption from the hydrate

    WA92: a fixed target experiment to trigger on and identify beauty particle decays

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    We describe the detectors and trigger system used in the CERN WA92 experiment. The experiment was designed to study the production and decay of beauty particles from 350 GeV/cc\, π\,\pi^- interactions in copper and tungsten targets. Charged particle tracking is performed using the Omega spectrometer. Silicon microstrip detectors are used to provide precise tracking information in the region of the production and the decay of heavy-flavoured particles and to trigger on the resulting high impact parameter tracks. The precision of vertex reconstruction corresponds to ±3.7%\pm 3.7\% of the mean B-decay proper lifetime. Lepton and high transverse momentum hadron signals are also used in the trigger, which accepts 29\% of B-decays and rejects 98\% of non-beauty interactions

    Measurement of the beauty production cross-section in 350 GeV/c π\pi^- -Cu interactions

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    Using a sample of 10810^8 triggered events, produced in π\pi^---\,Cu interactions at 350~GeV/c/c, we have identified 26 beauty events. The estimated background in this sample is 0.6±0.60.6 \pm 0.6 events. From these data, assuming a linear A-dependence, we measure a beauty production cross-section integrated over all xFx_F of 5.7+1.31.1 (stat.)+0.60.5 (syst.) 5.7 {+1.3 \atop -1.1}~{\mathrm {(stat.)}} {+0.6 \atop -0.5}~{\mathrm {(syst.)}}~nb/N

    Long-Term Programming of Antigen-Specific Immunity from Gene Expression Signatures in the PBMC of Rhesus Macaques Immunized with an SIV DNA Vaccine

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    While HIV-1-specific cellular immunity is thought to be critical for the suppression of viral replication, the correlates of protection have not yet been determined. Rhesus macaques (RM) are an important animal model for the study and development of vaccines against HIV/AIDS. Our laboratory has helped to develop and study DNA-based vaccines in which recent technological advances, including genetic optimization and in vivo electroporation (EP), have helped to dramatically boost their immunogenicity. In this study, RMs were immunized with a DNA vaccine including individual plasmids encoding SIV gag, env, and pol alone, or in combination with a molecular adjuvant, plasmid DNA expressing the chemokine ligand 5 (RANTES), followed by EP. Along with standard immunological assays, flow-based activation analysis without ex vivo restimulation and high-throughput gene expression analysis was performed. Strong cellular immunity was induced by vaccination which was supported by all assays including PBMC microarray analysis that identified the up-regulation of 563 gene sequences including those involved in interferon signaling. Furthermore, 699 gene sequences were differentially regulated in these groups at peak viremia following SIVmac251 challenge. We observed that the RANTES-adjuvanted animals were significantly better at suppressing viral replication during chronic infection and exhibited a distinct pattern of gene expression which included immune cell-trafficking and cell cycle genes. Furthermore, a greater percentage of vaccine-induced central memory CD8+ T-cells capable of an activated phenotype were detected in these animals as measured by activation analysis. Thus, co-immunization with the RANTES molecular adjuvant followed by EP led to the generation of cellular immunity that was transcriptionally distinct and had a greater protective efficacy than its DNA alone counterpart. Furthermore, activation analysis and high-throughput gene expression data may provide better insight into mechanisms of viral control than may be observed using standard immunological assays

    Linking capacity development to GOOS monitoring networks to achieve sustained ocean observation

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    Developing enduring capacity to monitor ocean life requires investing in people and their institutions to build infrastructure, ownership, and long-term support networks. International initiatives can enhance access to scientific data, tools and methodologies, and develop local expertise to use them, but without ongoing engagement may fail to have lasting benefit. Linking capacity development and technology transfer to sustained ocean monitoring is a win-win proposition. Trained local experts will benefit from joining global communities of experts who are building the comprehensive Global Ocean Observing System (GOOS). This two-way exchange will benefit scientists and policy makers in developing and developed countries. The first step toward the GOOS is complete: identification of an initial set of biological Essential Ocean Variables (EOVs) that incorporate the Group on Earth Observations (GEO) Essential Biological Variables (EBVs), and link to the physical and biogeochemical EOVs. EOVs provide a globally consistent approach to monitoring where the costs of monitoring oceans can be shared and where capacity and expertise can be transferred globally. Integrating monitoring with existing international reporting and policy development connects ocean observations with agreements underlying many countries' commitments and obligations, including under SDG 14, thus catalyzing progress toward sustained use of the ocean. Combining scientific expertise with international capacity development initiatives can help meet the need of developing countries to engage in the agreed United Nations (UN) initiatives including new negotiations for the conservation and sustainable use of marine biological diversity of areas beyond national jurisdiction, and the needs of the global community to understand how the ocean is changing
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