Space shuttle: Subsonic longitudinal and lateral-directional stability investigation of the MDAC LCR orbiter, unpowered and powered

Subsonic longitudinal and lateral directional stability investigation of MDAC LCR orbiter, unpowered and powered - graph

Stream invertebrate diversity reduces with invasion of river banks by non-native plants

1. Invasion of riparian zones by non-native plants is a global issue and commonly perceived as a challenge for river and fishery managers, but the type and extent of ecological changes induced by such invasions remain poorly understood. Established effects on sediment delivery, allochthonous inputs and channel shading could potentially alter aquatic macroinvertebrate assemblages, with implications for in-stream ecological quality. 2. We assessed responses in the diversity, quality and heterogeneity of stream macroinvertebrate communities to riparian invasion by non-native plants. Macroinvertebrates were collected from 24 sites on low order streams in central and southern Scotland during spring and autumn. The effect of invasive non-native plants (INNP) on macroinvertebrates was assessed relative to that of local physical and chemical factors. 3. INNP cover was associated with stronger effects than other factors on local diversity of macroinvertebrates (33% reduction at the highest INNP cover) but also increased macroinvertebrate abundance across sites. Invaded sites were also associated with lower macroinvertebrate biomonitoring scores. Community composition differed between invaded and uninvaded sites in autumn, but not in spring. However, INNP influence on macroinvertebrate composition was generally secondary to that of physicochemical variables (e.g. channel shade, substrate diversity). 4. We demonstrate that the influence of INNP extends beyond well-known impacts on plant communities to reductions mainly in stream macroinvertebrate diversity. Combined with the negative impact on pollution-sensitive macroinvertebrate taxa this raises concerns over the ecological health of streams with heavily invaded riparian zones. Our findings suggest that efforts to improve low order streams by actively managing severe riparian invasions are merited, but the size and uncertainty of the likely ecological gains must also be evaluated against the effort involved

Unexpected changes in community size structure in a natural warming experiment

Natural ecosystems typically consist of many small and few large organisms. The scaling of this negative relationship between body mass and abundance has important implications for resource partitioning and energy usage. Global warming over the next century is predicted to favour smaller organisms, producing steeper mass-abundance scaling and a less efficient transfer of biomass through the food web. Here, we show that the opposite effect occurs in a natural warming experiment involving 13 whole-stream ecosystems within the same catchment, which span a temperature gradient of 5-25 °C. We introduce a mechanistic model that shows how the temperature dependence of basal resource carrying capacity can account for these previously unexpected results. If nutrient supply increases with temperature to offset the rising metabolic demand of primary producers, there will be sufficient resources to sustain larger consumers at higher trophic levels. These new data and the model that explains them highlight important exceptions to some commonly assumed 'rules' about responses to warming in natural ecosystems

COVID-19: Rapid antigen detection for SARS-CoV-2 by lateral flow assay: A national systematic evaluation of sensitivity and specificity for mass-testing

Background Lateral flow device (LFD) viral antigen immunoassays have been developed around the world as diagnostic tests for SARS-CoV-2 infection. They have been proposed to deliver an infrastructure-light, cost-economical solution giving results within half an hour. Methods LFDs were initially reviewed by a Department of Health and Social Care team, part of the UK government, from which 64 were selected for further evaluation from 1st August to 15th December 2020. Standardised laboratory evaluations, and for those that met the published criteria, field testing in the Falcon-C19 research study and UK pilots were performed (UK COVID-19 testing centres, hospital, schools, armed forces). Findings 4/64 LFDs so far have desirable performance characteristics (orient Gene, Deepblue, Abbott and Innova SARS-CoV-2 Antigen Rapid Qualitative Test). All these LFDs have a viral antigen detection of >90% at 100,000 RNA copies/ml. 8951 Innova LFD tests were performed with a kit failure rate of 5.6% (502/8951, 95% CI: 5.1–6.1), false positive rate of 0.32% (22/6954, 95% CI: 0.20–0.48). Viral antigen detection/sensitivity across the sampling cohort when performed by laboratory scientists was 78.8% (156/198, 95% CI 72.4–84.3). Interpretation Our results suggest LFDs have promising performance characteristics for mass population testing and can be used to identify infectious positive individuals. The Innova LFD shows good viral antigen detection/sensitivity with excellent specificity, although kit failure rates and the impact of training are potential issues. These results support the expanded evaluation of LFDs, and assessment of greater access to testing on COVID-19 transmission. Funding Department of Health and Social Care. University of Oxford. Public Health England Porton Down, Manchester University NHS Foundation Trust, National Institute of Health Research

Vasectomy: a Long‐Term Study of its Effects on Testicular Endocrine Function in Man

Plasma testosterone, luteinizing hormone (L.H.) and follicle stimulating hormone (F.S.H.) were measured before operation in 39 males, aged 26 to 53 years with 2 to 5 children, seeking vasectomy for contraceptive purposes. These measurements were repeated at 3 and 12 months after vasectomy. Levels of L.H. at 12 months were significantly higher than pre‐vasectomy levels, suggesting some degree of decreased Leydig cell function. However, testosterone and F.S.H. levels were similar at the three sampling times. Continuing yearly measurements for at least 5 years are planned. Vasektomie: Eine Langzeit‐Studie über den Einfluß auf die endokrine Funktion der Hoden Bei 39 Männern im Alter von 26–53 Jahren (mit 2–5 Kindern) wurde eine Vasektomie zur Familienplanung durchgeführt; in diesen Fällen wurde vor, sowie 3 und 12 Monate nach dem operativen Eingriff eine Bestimmung von LH, FSH und Plasmatestosterone vorgenommen. Für LH kann festgestellt werden, daß 12 Monate nach der Vasektomie deutlich höhere Werte als vorher bestanden, was auf eine herabgesetzte Leydigzell‐funktion hinweist. Jedoch zeigte sich bei einer Bestimmung von Testosteron und FSH in etwa ein gleichsinniger Wert zu den drei Bestimmungsdaten. Es ist vorgesehen, diese Studie über 5 Jahre fortzüfiihren. Vasectomia: estudio de sus efectos a largo plazo, sobre la función endocrina del testículo humano En 39 hombres, entre 26 y 53 años de edad y con 2 a 5 hijos, se determinaron en plasma testosterona, LH y FSH, antes de practicárseles la vasectomía con fines anticonceptivos. Estas determinaciones se repitieron 3 y ‐ 12 meses después de la vasectomia. Los niveles de LH alos 12 meses, eran significativamente más altos que los niveles previos a la vasectomia, sugiriendo algún grado de disminución de la función de la célula de Leydig. No obstante, los niveles de testosterona y FSH fueron similares en tres muestras. Se ha planeado continuar efectuando determinaciones anuales al menos durante 5 años. 1976 Blackwell Verlag Gmb