322 research outputs found

    Absolute wave-number measurements in 130Te2: Reference lines spanning the 420.9-464.6-nm region

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    We have measured the absolute wave numbers of 39 transitions of 130Te2 spanning the spectral region of 420.9-464.6 nm to an accuracy of better than 2 parts in 109 by use of saturation spectroscopy and Fabry-Pérot interferometry. These measurements provide a set of convenient and accurate transfer standards for laser wavelength calibration spanning the entire Stilbene-420 dye-tuning curve

    Role of somatostatin receptors in normal and tumoral pituitary corticotropic cells

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    Normal and tumoral pituitary corticotropic cells express sst2and sst5, of which sst5is the predominantly expressed receptor subtype. Somatostatin (SS) inhibits pituitary adrenocorticotropin hormone (ACTH) secretion in vitro, but the sensitivity to SS is strongly regulated by glucocorticoids. In pathological conditions of a low endogenous cortisol level, i.e. in patients with adrenal insufficiency and in patients with Nelson's syndrome, SS and sst2-preferring SS analogs (SSA), such as octreotide, are able to lower circulating ACTH and cortisol levels. On the other hand, sst2-preferring SSA seem not effective in lowering ACTH and cortisol levels in patients with untreated Cushing's disease (CD), in which circulating cortisol levels are high. This is likely due to the downregulation of sst2receptors by glucocorticoids. sst5receptor expression is more resistant to the inhibitory effect of glucocorticoids. In recent years, novel sst subtype-selective and universal SSA have been developed. In particular, SSA with a high sst5-binding affinity are potent inhibitors of ACTH secretion by pituitary corticotropic adenoma cells. This knowledge has initiated clinical trials evaluating the efficacy of these novel SSA in patients with CD, with the aim to lower circulating ACTH and cortisol levels by targeting multiple ssts on the corticotropic adenoma cells. In this minireview, the effects of SS in the regulation of normal and tumoral ACTH secretion, the role of sst subtypes involved herein, as well as the potentials of novel SSA in the treatment of patients with recurrent or persisting CD are discussed

    Plant uptake and stream chemistry set global bounds on nitrogen gas emissions from humid tropical forests

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    Denitrification and hydrologic leaching are the two major pathways by which nitrogen is lost from the terrestrial biosphere. Humid tropical forests are thought to dominate denitrification from unmanaged lands globally, but there is large uncertainty about the range and key drivers of total N gas emissions across the biome. We combined pantropical measures of small watershed stream chemistry with ecosystem modeling to determine total nitrogen gas losses and associated uncertainty across humid tropical forests. Our calculations reveal that denitrification in soils and along hydrologic flowpaths contributes on average \u3e45% of total watershed N losses. However, when denitrification occurs exclusively in shallow soils, simulations indicate that gas emissions would exceed N inputs and render plants severely N-limited, which contradicts observations of widespread N-sufficiency in tropical forests. Our analyses suggest an upper bound on soil denitrification of ~80% of total external N losses beyond which tropical plant growth would be compromised

    The link between catchment precipitation forecast skill and spread to that of downstream ensemble hydrological forecasts

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    Operational rainfall and flood forecasting systems across the world are increasingly using ensemble approaches. Such systems are operated by the Flood Forecasting Centre (FFC) and Scottish Flood Forecasting Service (SFFS) across Great Britain producing ensemble gridded hydrological forecasts for the next 5-6 days. In order to maximise the practical day-to-day use of these systems for decision-making and warning, duty hydro-meteorologists require a sound understanding of both the meteorological and hydrological ensemble forecast skill. In this work, a common verification framework is defined and used in order to understand the relative levels of skill in both rainfall and river flow forecasting systems. A blended 24-member ensemble precipitation forecast, produced by the Met Office, is used to drive the operational distributed hydrological model in ensemble mode. The hydrological forecasts provide output every 15 minutes out to 6 days on a 1km grid. The blended rainfall forecast is a mixture of the 2.2 km MOGREPS-UK ensemble up to 36h and the 32 km global MOGREPS-G ensemble at longer lead-times. The forecasts are interpolated on to a common 2 km grid and the hydrological model used is the Grid-to-Grid model (G2G) developed by the Centre for Ecology & Hydrology. To establish an upper bound on skill, assessments over a daily lead-time interval are studied first, and will be the focus here. Spatial and regional variations in forecast skill are compared between the precipitation (e.g. daily accumulations) and the river flow forecasts. Also of interest is the impact of catchment size and how to pool and present the skill metrics in a meaningful way for end-users. For precipitation, the impact of observation type: gridded gauge-only analyses and a radar-derived (gauge calibrated) precipitation product, is compared to quantify the uncertainty that comes from the observations. Of particular interest is understanding how the spread in the precipitation forecast is modulated by the downstream hydrological model. Is it inflated, does it remain comparable, or is it reduced? The work aims to establish the basis for a real-time monitoring tool that can assist hydro-meteorologists in their interpretation of operational ensemble forecasts, and facilitate associated decision making processes

    Depressed Neuromuscular Transmission Causes Weakness in Mice Lacking BK Potassium Channels

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    Mice lacking functional large-conductance voltage- and Ca2+-activated K+ channels (BK channels) are viable but have motor deficits including ataxia and weakness. The cause of weakness is unknown. In this study, we discovered, in vivo, that skeletal muscle in mice lacking BK channels (BK−/−) was weak in response to nerve stimulation but not to direct muscle stimulation, suggesting a failure of neuromuscular transmission. Voltage-clamp studies of the BK−/− neuromuscular junction (NMJ) revealed a reduction in evoked endplate current amplitude and the frequency of spontaneous vesicle release compared with WT littermates. Responses to 50-Hz stimulation indicated a reduced probability of vesicle release in BK−/− mice, suggestive of lower presynaptic Ca2+ entry. Pharmacological block of BK channels in WT NMJs did not affect NMJ function, surprisingly suggesting that the reduced vesicle release in BK−/− NMJs was not due to loss of BK channel–mediated K+ current. Possible explanations for our data include an effect of BK channels on development of the NMJ, a role for BK channels in regulating presynaptic Ca2+ current or the effectiveness of Ca2+ in triggering release. Consistent with reduced Ca2+ entry or effectiveness of Ca2+ in triggering release, use of 3,4-diaminopyridine to widen action potentials normalized evoked release in BK−/− mice to WT levels. Intraperitoneal application of 3,4-diaminopyridine fully restored in vivo nerve-stimulated muscle force in BK−/− mice. Our work demonstrates that mice lacking BK channels have weakness due to a defect in vesicle release at the NMJ

    Plastic recycling stripped naked – from circular product to circular industry with recycling cascade

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    This perspective combines various expertise to develop and analyse the concept of technology cascade for recycling waste plastics with the goal of displacing as much fossil crude oil as possible. It thereby presents archetype recycling technologies with their strengths and weaknesses. It then combines them in various cascades to process a representative plastic mix, and determines how much (fossil) naphtha could be displaced and at which energy consumption. The cascades rely on a limited number of parameters that are fully reported in supplementary information and that were used in a simple and transparent spreadsheet model. The calculated results bust several common myths in plastic recycling, e. g. by prioritizing here recycled volume over recycling efficiency, and prioritizing circular industry over circular products. It unravels the energy cost of solvent-based recycling processes, shows the key role of gasification and the possibility to displace up to 70 % of the fossil feedstock with recycled carbon, a recycling rate that compares well with that aluminium, steel or paper. It suggests that deeper naphtha displacement would require exorbitant amount of energy. It therefore argues for the need to complement recycling with the use of renewable carbon, e. g. based on biomass, to fully defossilise the plastic industry.</p

    Crowdfunding biodiversity conservation

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    Raising funds is critical for conserving biodiversity and hence so too is scrutinizing emerging financial mechanisms that might help achieve this goal. In this context, anecdotal evidence indicates crowdfunding is being used to support a variety of activities needed for biodiversity conservation, yet its magnitude and allocation remain largely unknown. We conducted a global analysis to help address this knowledge gap, based on empirical data from conservation‐focused projects extracted from crowdfunding platforms. For each project, we determined the funds raised, date, country of implementation, proponent characteristics, activity type, biodiversity realm, and target taxa. We identified 72 relevant platforms and 577 conservation‐focused projects that have raised US$4 790 634 since 2009. Whilst proponents were based in 38 countries, projects were delivered across 80 countries, indicating a potential mechanism of resource mobilization. Proponents were from non‐governmental organizations (35%), universities (30%), or were freelancers (26%). Most projects were for research (40%), persuasion (31%), and on‐ground actions (21%). Projects have focused primarily on species (57.7%) and terrestrial ecosystems (20.3%), and less on marine (8.8%) and freshwater ecosystems (3.6%). Projects have focused on 208 species, including a disproportionate number of threatened bird and mammal species. Crowdfunding for biodiversity conservation has now become a global phenomenon and presents signals for potential expansion, despite possible pitfalls. Opportunities arise from its spatial amplifying effect, steady increase over time, inclusion of Cinderella species, adoption by multiple actors, and funding of a range of activities beyond research. Our study paves the way for further research on key questions, such as campaign success rates, effectiveness, and drivers of adoption. Even though the capital input of crowdfunding so far has been modest compared to other conservation finance mechanisms, its contribution goes beyond funding research and providing capital. Embraced with due care, crowdfunding could potentially become an increasingly important financial mechanism for biodiversity conservation

    Forecasting snowmelt flooding over Britain using the Grid-to-Grid model: a review and assessment of methods

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    In many regions of high annual snowfall, snowmelt modelling can prove to be a vital component of operational flood forecasting and warning systems. Although Britain as a whole does not experience prolonged periods of lying snow, with the exception of the Scottish Highlands, the inclusion of snowmelt modelling can still have a significant impact on the skill of flood forecasts. Countrywide operational flood forecasts over Britain are produced using the national Grid-to-Grid (G2G) distributed hydrological model. For Scotland, snowmelt is included in these forecasts through a G2G snow hydrology module involving temperature-based snowfall/rainfall partitioning and functions for temperature-excess snowmelt, snowpack storage and drainage. Over England and Wales, the contribution of snowmelt is included by pre-processing the precipitation prior to input into G2G. This removes snowfall diagnosed from weather model outputs and adds snowmelt from an energy budget land surface scheme to form an effective liquid water gridded input to G2G. To review the operational options for including snowmelt modelling in G2G over Britain, a project was commissioned by the Environment Agency through the Flood Forecasting Centre (FFC) for England and Wales and in partnership with the Scottish Environment Protection Agency (SEPA) and Natural Resources Wales (NRW). Results obtained from this snowmelt review project will be reported on here. The operational methods used by the FFC and SEPA are compared on past snowmelt floods, alongside new alternative methods of treating snowmelt. Both case study and longer-term analyses are considered, covering periods selected from the winters 2009-2010, 2012-2013, 2013-2014 and 2014-2015. Over Scotland, both of the snowmelt methods used operationally by FFC and SEPA provided a clear improvement to the river flow simulations. Over England and Wales, fewer and less significant snowfall events occurred, leading to less distinction in the results between the methods. It is noted that, for all methods considered,large uncertainties remain in flood forecasts influenced by snowmelt. Understanding and quantifying these uncertainties should lead to more informed flood forecasts and associated guidance information

    Biochemical predictors of outcome of pituitary surgery for cushing's disease

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    Objective: Transsphenoidal surgery (TS) is the primary therapy for Cushing's disease (CD). The aims of this retrospective study were twofold: (i) investigate early and late results of TS forCD, and (ii) evaluate various postoperative tests in order to predict the outcome of TS. Methods: We reviewed the long-term outcome in 79 patients with CD who underwent TS (median follow-up 84 months, range 6-197). Within 2 weeks after surgery, morning serum cortisol concentrations were obtained (n = 78) and corticotropin-releasing hormone (CRH) (n = 53) and metyrapone tests (n = 72) were performed. Three groups of outcome were identified: sustained remission, early failure (persistent CD), and late relapse. Results: Immediate postoperative remission was achieved in 51 patients (65%), whereas 28 patients (35%) had persistent CD after TS. Ten patients developed recurrent CD after initial remission (20%). Morning cortisol: all relapses but one recorded serum cortisol >50 nmol/l. A cortisol threshold value of 200 nmol/l has a positive predictive value of 79% for immediate surgical failure (negative predictive failure [NPV] 97%). CRH test: CRH-stimulated peak cortisol ≥600 nmol/l predicted early failure in 78% (NPV 100%). All relapses recorded CRH-stimulated peak cortisol ≥485 nmol/l. Metyrapone test: 11-deoxycortisol ≥345 nmol/l predicted an early failure in 86% of cases (NPV 94%). Conclusion: Predictive factors of surgical failure are morning cortisol ≥200 nmol/l, 11-deoxycortisol ≥345 nmol/l after metyrapone and CRH-stimulated cortisol ≥600 nmol/l. CRH and/or metyrapone testing are not superior to morning cortisol concentration in the prediction of outcome of TS. Careful long-term follow-up remains necessary independent of the outcome of biochemical testing. Copyrigh
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