513 research outputs found

    Viewing stomata in action: Autonomous in planta imaging of individual stomatal movement links morphology and kinetics

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    Stomata regulate plant gas exchange with the environment, balancing between water loss and CO2 uptake. Gas exchange dynamics are influenced by traits such as stomatal morphology, size and density, which are commonly investigated using imprints and manual microscopy, methods that are destructive and time consuming. Moreover, these microscopic properties are statically sampled and related to the dynamic ensemble behavior: gas exchange of an entire plant or part of a leaf. Knowledge on how morphology, size and density of stomata influence the movement of individual stomata is limited. We developed a compact microscope system that can measure the kinetics of tens of stomata in vivo simultaneously, with sub-minute time resolution. The system can be deployed in the plant’s growth environment, at minimal impact on leaf microclimate. The characteristics of our microscope and data analyses are described, and we demonstrate its capabilities on Chrysanthemum morifolium with novel insight into individual stomata’s contribution to water-use efficienc

    Fluctuating light takes crop photosynthesis on a rollercoaster ride

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    Crops are regularly exposed to frequent irradiance fluctuations, which20 decrease their integrated CO2 assimilation and affect their phenotyp

    Lead Poisoning: An Alarming Public Health Problem in Bangladesh

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    To assess the risk of lead poisoning among preschool and school-aged children in Bangladesh, 345 children were screened for blood lead levels (BLLs) from one rural and two urban areas in Bangladesh from September 2007 through January 2008. An urban industrial area at Tongi was identified as a disaster area, where 99% (104/105) of those tested had BLLs ≥ 10 μg/dL. Industrial emissions and use of leaded gasoline by two-stroke engine vehicles were identified as possible sources of lead in that area. A rural nonindustrial area at Chirirbandar, Dinajpur was identified as another high-risk area, where 14% of the children screened had BLLs ≥ 10 μg/dL. BLLs at the urban industrial area were significantly higher than those at the rural and urban nonindustrial areas (24.58 ± 10.32, 7.24 ± 6.31, and 2.47 ± 3.32 μg/dL, respectively; p <0.001). Weight-for-age z-scores of the urban children were significantly lower than that of the rural children (–1.41 ± 1.88 vs. 0.20 ± 1.16, p <0.001). Children with elevated BLLs had poorer nutritional status (p = 0.05) than those with normal BLLs. Over 90% of the parents did not know that lead causes health problems. In conclusion, the problem of lead poisoning in children was found to be high in both urban and rural Bangladesh. A universal lead screening for preschool and school-aged children and a lead education program for parents are recommended for implementation in Bangladesh

    S-wave Kpi scattering in chiral perturbation theory with resonances

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    We present a detailed analysis of S-wave Kpi scattering up to 2 GeV, making use of the resonance chiral Lagrangian predictions together with a suitable unitarisation method. Our approach incorporates known theoretical constraints at low and high energies. The present experimental status, with partly conflicting data from different experiments, is discussed. Our analysis allows to resolve some experimental ambiguities, but better data are needed in order to determine the cross-section in the higher-energy range. Our best fits are used to determine the masses and widths of the relevant scalar resonances in this energy region.Comment: 40 pages, 6 figure

    A Central Excess of Stripped-Envelope Supernovae within Disturbed Galaxies

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    This paper presents an analysis of core-collapse supernova distributions in isolated and interacting host galaxies, paying close attention to the selection effects involved in conducting host galaxy supernova studies. When taking into account all of the selection effects within our host galaxy sample, we draw the following conclusions: i) Within interacting, or 'disturbed', systems there is a real, and statistically significant, increase in the fraction of stripped-envelope supernovae in the central regions. A discussion into what may cause this increased fraction, compared to the more common type IIP supernovae, and type II supernovae without sub-classifications, is presented. Selection effects are shown not to drive this result, and so we propose that this study provides direct evidence for a high-mass weighted initial mass function within the central regions of disturbed galaxies. ii) Within 'undisturbed' spiral galaxies the radial distribution of type Ib and type Ic supernovae is statistically very different, with the latter showing a more centrally concentrated distribution. This could be driven by metallicity gradients in these undisturbed galaxies, or radial variations in other properties (binarity or stellar rotation) driving envelope loss in progenitor stars. This result is not found in 'disturbed' systems, where the distributions of type Ib and Ic supernovae are consistent.Comment: Accepted for publication in MNRA

    Radiofrequency pancreatic ablation and section of the main pancreatic duct does not lead to necrotizing pancreatitis

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    [EN] Objective: Determine whether Radiofrequency ablation (RFA) of the pancreas and subsequent transection of the main pancreatic duct may avoid the risk of both necrotizing pancreatitis and postoperative pancreatic fistula (POPF) formation. Methods: Thirty-two rats were subjected to RFA and section of the pancreas over their portal vein. Animals were killed at 3, 7, 15 and 21 days (Groups 0-3, respectively). Two additional control groups (sham operation and user manipulation only, respectively) of 15 days of postoperative period were considered. Postoperative complications, histological changes (including morphometric and immunohistochemical analysis) and incidence of POPF were evaluated. Results: A significant increase in serum amylase levels (p<0.05) on the 3rd postoperative day which return to baseline levels in the following weeks was noted in groups 0-3. Those groups showed a rapid atrophy of the distal pancreas by apoptosis with no signs of necrotizing pancreatitis or POPF. The distal pancreas in groups 1-3 compared to group 0 and control groups showed a significant increase of small islets (<1000 μm 2 ). Conclusions: The rapid acinar atrophy of the distal pancreas after RFA and section of the pancreatic ducts in this model does not lead to necrotizing pancreatitis.This research has been supported by grant TEC2011-27133-C02-02 from the Spanish Government and the European Economic Community.Quesada, R.; Burdío, F.; Iglesias, M.; Dorcaratto, D.; Cáceres, M.; Andaluz, A.; Poves, I.... (2014). Radiofrequency pancreatic ablation and section of the main pancreatic duct does not lead to necrotizing pancreatitis. Pancreas. 43(6):931-937. doi:10.1097/MPA.0000000000000156S93193743

    Luminous Blue Variable eruptions and related transients: Diversity of progenitors and outburst properties

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    We present new light curves and spectra for a number of extragalactic optical transients or "SN impostors" related to giant eruptions of LBVs, and we provide a comparative discussion of LBV-like giant eruptions known to date. New data include photometry and spectroscopy of SNe1999bw, 2000ch, 2001ac, 2002bu, 2006bv, and 2010dn. SN2010dn resembles SN2008S and NGC 300-OT, whereas SN2002bu shows spectral evolution from a normal LBV at early times to a twin of these cooler transients at late times. SN2008S, NGC300-OT, and SN2010dn appear to be special cases of a broader eruptive phenomenon where the progenitor star was enshrouded by dust. Examining the full sample, SN impostors have range of timescales from a day to decades, potentially suffering multiple eruptions. The upper end of the luminosity distribution overlaps with the least luminous SNe. The low end of the luminosity distribution is poorly defined, and a distinction between various eruptions is not entirely clear. We discuss observational clues concerning winds or shocks as the relevant mass-loss mechanism, and we evaluate possible ideas for physical mechanisms. Although examples of these eruptions are sufficient to illustrate their diversity, their statistical distribution will benefit greatly from upcoming transient surveys. Based on the distribution of eruptions, we propose that SN1961V was not a member of this class of impostors, but was instead a true core-collapse SNIIn preceded by a giant LBV eruption. (abridged)Comment: 36(!) journal pages, 16 figures. submitted to MNRAS on october 12. coments welcome. updated reference
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