778 research outputs found
Research Note:<br>Derivation of temperature lapse rates in semi-arid south-eastern Arizona
International audienceEcological and hydrological modelling at the regional scale requires distributed information on weather variables, and temperature is important among these. In an area of basin and range topography with a wide range of elevations, such as south-eastern Arizona, measurements are usually available only at a relatively small number of locations and elevations, and temperatures elsewhere must be estimated from atmospheric lapse rate. This paper derives the lapse rates to estimate maximum, minimum and mean daily temperatures from elevation. Lapse rates were calculated using air temperatures at 2 m collected during 2002 at 18 locations across south-eastern Arizona, with elevations from 779 to 2512 m. The lapse rate predicted for the minimum temperature was lower than the mean environmental lapse rate (MELR), i.e. 6 K km?1, whereas those predicted for the mean and maximum daily temperature were very similar to the MELR. Lapse rates were also derived from radiosonde data at 00 and 12 UTC (5 pm and 5 am local time, respectively). The lapse rates calculated from radiosonde data were greater than those from the 2 m measurements, presumably because the effect of the surface was less. Given temperatures measured at Tucson airport, temperatures at the other sites were predicted using the different estimates of lapse rates. The best predictions of temperatures used the locally predicted lapse rates. In the case of maximum and mean temperature, using the MELR also resulted in accurate predictions. Keywords: near surface lapse rates, semi-arid climate, mean minimum and maximum temperatures, basin and range topograph
Generalized oscillator strength for Na 3s-3p transition
Generalized oscillator strengths (GOS's) for the Na transition have
been investigated using the spin-polarized technique of the random phase
approximation with exchange (RPAE) and the first Born approximation (FBA),
focussing our attention on the position of the minimum. Intershell correlations
are found to influence the position of the minimum significantly, but hardly
that of the maximum. The RPAE calculation predicts for the first time the
positions of the minimum and maximum at momentum transfer, values of 1.258
a.u. and 1.61 a.u., respectively. The former value is within the range of
values extracted from experimental measurements, a.u.. We
recommend careful experimental search for the minimum around the predicted
value for confirmation.Comment: 11 pages, 2figure
The Critical Role of Spreading Depolarizations in Early Brain Injury: Consensus and Contention
Background: When a patient arrives in the emergency department following a stroke, a traumatic brain injury, or sudden cardiac arrest, there is no therapeutic drug available to help protect their jeopardized neurons. One crucial reason is that we have not identified the molecular mechanisms leading to electrical failure, neuronal swelling, and blood vessel constriction in newly injured gray matter. All three result from a process termed spreading depolarization (SD). Because we only partially understand SD, we lack molecular targets and biomarkers to help neurons survive after losing their blood flow and then undergoing recurrent SD. Methods: In this review, we introduce SD as a single or recurring event, generated in gray matter following lost blood flow, which compromises the Na/K pump. Electrical recovery from each SD event requires so much energy that neurons often die over minutes and hours following initial injury, independent of extracellular glutamate. Results: We discuss how SD has been investigated with various pitfalls in numerous experimental preparations, how overtaxing the Na/K ATPase elicits SD. Elevated K or glutamate are unlikely natural activators of SD. We then turn to the properties of SD itself, focusing on its initiation and propagation as well as on computer modeling. Conclusions: Finally, we summarize points of consensus and contention among the authors as well as where SD research may be heading. In an accompanying review, we critique the role of the glutamate excitotoxicity theory, how it has shaped SD research, and its questionable importance to the study of early brain injury as compared with SD theory.This work was supported by grants from the Heart and Stroke Foundation of Canada and the National Science and Engineering Research Council of Canada to RDA, an NIH grant (NS106901) to CWS, a National Research, Development and Innovation Office of Hungary grant (K1343777) and EU Horizon 2020 research and innovation program (739953) to EF and from DFG Deutsche Forschungsgemeinschaft (German Research Council) (DFG DR 323/5-1), DFG DR 323/10-1, and BMBF Bundesministerium fuer Bildung und Forschung (EraNet Neuron EBio2, with funds from BMBF 01EW2004) to JPD
The challenges of long-term invasive mammal management: lessons from the UK
We consider the motivations, strategies, and costs involved in invasive mammal management undertaken in the UK. Widespread established invasive mammals require longâterm management to limit damage or spread, but ongoing management is costly and complex. Longâterm management is most effective where it is applied at a landscape scale, but this requires overarching coâordination between multiple stakeholders. Five challenges for successful longâterm management of invasive mammal species are identified as follows: defining landscapeâscale strategies, management coâordination, stakeholder and community engagement, sustainable funding, and evidence requirements. We make recommendations on the supportive infrastructure needed for effective landscapeâscale management of invasive mammals to fulfil longâterm conservation aims, as follows. 1. There is a need for evidenceâbased Invasive Species Action Plans to provide strategy for the longâterm ongoing management of prioritised species at appropriate scales. 2. Where possible, multispecies approaches to invasive species management should be adopted. 3. Trusted leadership should be identified to take ownership of Action Plans and provide an overarching coâordination to bring individuals, organisations, and funders together. 4. Support for a centralised hub for training, data, and knowledge flows will greatly improve scientific outcomes through a searchable evidence base, and via best practice and knowledge sharing
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