942 research outputs found

    Развитие МБА в современных условиях (региональный аспект)

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    Precipitation is an important hydro-meteorological variable, and is a primary driver of the water cycle. In large parts of the world, real-time ground-based observations of precipitation are sparse and satellite-derived precipitation products are the only information source.We used changes in satellite-derived soil moisture (SM) and land surface temperature (LST) to reduce uncertainties in the real-time TRMM Multi-satellite Precipitation Analysis product (TMPA-RT). The Variable Infiltration Capacity (VIC) model was used to model the response of LST and SM on precipitation, and a particle filter was used to update TMPA-RT. Observations from AMSR-E (LPRM and LSMEM), ASCAT, SMOS and LST from AMSR-E were assimilated to correct TMPA-RT over the continental United States.Assimilation of satellite-based SM observations alone reduced the false detection of precipitation (by 85.4%) and the uncertainty in the retrieved rainfall volumes (5%). However, a higher number of observed rainfall events were not detected after assimilation (34%), compared to the original TMPA-RT (46%). Noise in the retrieved SM changes resulted in a relatively low potential to reduce uncertainties. Assimilation of LST observations alone increased the rainfall detection rate (by 51%), and annual precipitation totals were closer to ground-based precipitation observations. Combined assimilation of both satellite SM and LST, did not significantly reduce the uncertainties compared to the original TMPA-RT, because of the influence of satellite SM over LST. However, in central United States improvements were found after combined assimilation of SM and LST observations. This study shows the potential for reducing the uncertainties in TMPA-RT estimates over sparsely gauged areas

    Підтексти драм Лесі Українки

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    У драмах Лесі Українки має місце діалог з культурою декадансу, який увиразнює тематику меланхолії та похідних від неї мотивів усамітнення, небуття, долі, жертви.In Lesya Ukrainka’s dramas the dialogue with the culture of decadence is conducted that entails the prominent place of the theme of melancholy and the derivative motifs of solitude, non-existence, fate, martyr

    The role and ultrastructure of the liver sinusoidal endothelial cell in fasting, hepatoxicity, and ageing

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    The majority of liver studies focus on the hepatocyte however the work of this thesis investigates the vital role of the liver sinusoidal endothelial cell (LSEC). LSECs line the liver sinusoids forming a protective barrier between the blood and hepatocytes. The LSEC cytoplasm resembles a sieve, perforated with thousands of transcellular pores of approximately 50-150 nm in diameter called fenestrations, and is underlined by a very sparse extracellular matrix. This facilitates the virtually unimpeded passage of fluid and substances smaller than fenestrations from the blood such as drugs and nutrients, and size-dependent filtration of lipoproteins, to and from hepatocytes. Fenestrations are dynamic structures, in that their size and number can be modulated by hormones, drugs, hepatotoxins, and diseases. Reduction of LSEC fenestration size and number (defenestration) is associated with ageing and pathological states, and is also a cause of hyperlipidemia and reduced drug clearance, thus changes in LSEC morphology can affect the entire organism. This thesis aims to broaden knowledge of the role and ultrastructure of the LSEC in physiological and toxicological states by investigating: whether there is fenestration modulation during fasting that could facilitate increased nutrient exchange between the blood and hepatocytes; whether changes to LSEC ultrastructure during acetaminophen hepatotoxicity are consistent with exacerbation of liver injury and/or with the facilitation of liver regeneration after severe necrosis; whether a substance that targets the LSEC could have a therapeutic benefit in acetaminophen hepatotoxicity by protecting the microvasculature from damage; whether isolation and culture of LSECs from ageing rats maintain the ageing (defenestrated) phenotype, and thus whether it is a valid method to study therapeutic substances in vitro that could reverse defenestration-related ailments associated with normal ageing

    Reverberation Mapping and the Physics of Active Galactic Nuclei

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    Reverberation-mapping campaigns have revolutionized our understanding of AGN. They have allowed the direct determination of the broad-line region size, enabled mapping of the gas distribution around the central black hole, and are starting to resolve the continuum source structure. This review describes the recent and successful campaigns of the International AGN Watch consortium, outlines the theoretical background of reverberation mapping and the calculation of transfer functions, and addresses the fundamental difficulties of such experiments. It shows that such large-scale experiments have resulted in a ``new BLR'' which is considerably different from the one we knew just ten years ago. We discuss in some detail the more important new results, including the luminosity-size-mass relationship for AGN, and suggest ways to proceed in the near future.Comment: Review article to appear in Astronomical Time Series, Proceedings of the Wise Observatory 25th Ann. Symposium. 24 pages including 7 figure

    No Guts, No Glory? How Risk-Taking Shapes Dominance, Prestige, and Leadership Endorsement

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    Risk-taking can fuel innovation and growth, but it can also have devastating consequences for individuals and organizations. Here we examine whether risk-taking affords social-hierarchical benefits to risk-takers. Specifically, we investigate how risk-taking influences perceived dominance, prestige, and the willingness to endorse risk-takers’ leadership. Integrating insights from costly signaling theory and the dominance/ prestige framework of social rank, we theorized that risk-taking increases leadership endorsement to the degree that it fuels perceptions of prestige, but decreases leadership endorsement to the degree that it fuels perceptions of dominance. However, we also hypothesized that risk-induced perceptions of dominance do translate into leadership endorsement in competitive (rather than cooperative) intergroup settings. We tested these hypotheses in four studies involving different samples, methods, and operationalizations. In Study 1, participants performed an implicit association test (IAT) that revealed that people associate risk with leader positions, and safety with follower positions. Study 2 was a longitudinal field survey conducted during the September 2019 Israeli elections, which showed that voters’ perceptions of politicians’ risk-taking propensities prior to the elections positively predicted perceived dominance and prestige as well as voting behavior during the elections. Finally, Studies 3 and 4 demonstrated that people are willing to support risktakers as leaders in the context of competitive (as opposed to cooperative) intergroup situations, because perceived dominance positively predicts leadership endorsement in competitive (but not cooperative) intergroup settings. We discuss implications for understanding the social dynamics of organizational rank and the perpetuation of risky behavior in organizations, politics, and society at large

    Stress Exposure and the Course of ADHD from Childhood to Young Adulthood:Comorbid Severe Emotion Dysregulation or Mood and Anxiety Problems

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    BACKGROUND: Compared to typically developing individuals, individuals with attention-deficit-hyperactivity disorder (ADHD) are on average more often exposed to stressful conditions (e.g., school failure, family conflicts, financial problems). We hypothesized that high exposure to stress relates to a more persistent and complex (i.e., multi-problem) form of ADHD, while low-stress exposure relates to remitting ADHD over the course of adolescence. METHOD: Longitudinal data (ages 11, 13, 16, and 19) came from the Tracking Adolescents' Individual Life Survey (TRAILS). We selected children diagnosed with ADHD (n = 244; 167 males; 77 females) from the TRAILS clinical cohort and children who screened positive (n = 365; 250 males; 115 females) and negative (gender-matched: n = 1222; 831 males; 391 females) for ADHD from the TRAILS general population sample cohort (total n = 1587). Multivariate latent class growth analysis was applied to parent- and self-ratings of stress exposure, core ADHD problems (attention problems, hyperactivity/impulsivity), effortful control, emotion dysregulation (irritability, extreme reactivity, frustration), and internalizing problems (depression, anxiety, somatic complaints). RESULTS: Seven distinct developmental courses in stress exposure and psychopathology were discerned, of which four related to ADHD. Two persistent ADHD courses of severely affected adolescents were associated with very high curvilinear stress exposure peaking in mid-adolescence: (1) Severe combined type with ongoing, severe emotional dysregulation, and (2) combined type with a high and increasing internalization of problems and elevated irritability; two partly remitting ADHD courses had low and declining stress exposure: (3) inattentive type, and (4) moderate combined type, both mostly without comorbid problems. CONCLUSIONS: High-stress exposure between childhood and young adulthood is strongly intertwined with a persistent course of ADHD and with comorbid problems taking the form of either severe and persistent emotion dysregulation (irritability, extreme reactivity, frustration) or elevated and increasing irritability, anxiety, and depression. Conversely, low and declining stress exposure is associated with remitting ADHD and decreasing internalizing and externalizing problems. Stress exposure is likely to be a facilitating and sustaining factor in these two persistent trajectories of ADHD with comorbid problems into young adulthood. Our findings suggest that a bidirectional, continuing, cycle of stressors leads to enhanced symptoms, in turn leading to more stressors, and so forth. Consideration of stressful conditions should, therefore, be an inherent part of the diagnosis and treatment of ADHD, to potentiate prevention and interruption of adverse trajectories

    Steps Toward Determination of the Size and Structure of the Broad-Line Region in Active Galactic Nuclei. XV. Long-Term Optical Monitoring of NGC 5548

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    We present the results of three years of ground-based observations of the Seyfert 1 galaxy NGC 5548, which combined with previously reported data, yield optical continuum and broad-line H-beta light curves for a total of eight years. The light curves consist of over 800 points, with a typical spacing of a few days between observations. During this eight-year period, the nuclear continuum has varied by more than a factor of seven, and the H-beta emission line has varied by a factor of nearly six. The H-beta emission line responds to continuum variations with a time delay or lag of 10-20 days, the precise value varying somewhat from year to year. We find some indications that the lag varies with continuum flux in the sense that the lag is larger when the source is brighter.Comment: 29 pages, 6 figures. Accepted for publication in ApJ (1999 Jan 10

    Ecologie en beheersing van zwarte vlekkenziekte in peen : resultaten onderzoek 2005/2006

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    Bij Parijse peen en waspeen treden er al voor de oogst vaak verschijnselen op waarbij donkere vlekken ontstaan. De partij peen kan hierdoor onverkoopbaar worden. In dit project is getracht om de oorzaak te vinden. De aangeleverde penen bleken aangetast te zijn door Rhizoctonia solani. Er werd geen relatie met de aanwezigheid van nematoden vastgesteld. Wel leek er een relatie met de pH te zijn

    Correlated X-ray/Ultraviolet/Optical variability in the very low mass AGN NGC 4395

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    We report the results of a one year Swift X-ray/UV/optical programme monitoring the dwarf Seyfert nucleus in NGC 4395 in 2008-2009. The UV/optical flux from the nucleus was found to vary dramatically over the monitoring period, with a similar pattern of variation in each of the observed UV/optical bands (spanning 1900 - 5500 {\AA}). In particular, the luminosity of NGC 4395 in the 1900 {\AA} band changed by more than a factor of eight over the monitoring period. The fractional variability was smaller in the UV/optical bands than that seen in the X-rays, with the X-ray/optical ratio increasing with increasing flux. Pseudo-instantaneous flux measurements in the X-ray and each UV/optical band were well correlated, with cross correlation coefficients of >0.7, significant at 99.9 per cent confidence. Archival Swift observations from 2006 sample the intra-day X-ray/optical variability on NGC 4395. These archival data show a very strong correlation between the X-ray and b bands, with a cross-correlation coefficient of 0.84 (significant at >99 per cent confidence). The peak in the cross correlation function is marginally resolved and asymmetric, suggesting that X-rays lead the b band, but by 1 hour. In response to recent (August 2011) very high X-ray flux levels from NGC4395 we triggered Swift ToO observations, which sample the intra-hour X-ray/UV variability. These observations indicate, albeit with large uncertainties, a lag of the 1900 {\AA} band behind the X-ray flux of ~400 s. The tight correlation between the X-ray and UV/optical lightcurves, together with the constraints we place on lag time-scale are consistent with the UV/optical variability of NGC 4395 being primarily due to reprocessing of X-ray photons by the accretion disc.Comment: 11 pages, 9 figures, 3 tables. Accepted for publication in MNRA
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