230 research outputs found

    TB63: Variation in Foliar Nutrient Concentrations in Red Spruce

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    Red spruce (Picea rubens Sarg.) is an important pulpwood species in northern New England and Canada. Management objectives favor this species and the closely related black spruce (Picea mariana Mill. BSP) on many sites. Foliar nutrient concentrations of unfertilized, economically mature, red spruce trees growing on four different sites and over two- and three-year periods are presented here and compared to foliar concentrations reported by other scientists.https://digitalcommons.library.umaine.edu/aes_techbulletin/1136/thumbnail.jp

    The Crystal Structure of (2,3,9,10-tetramethyl-1,4,8,11-tetraaza- 1,3,8, 10-cyclotetradecatetraene )copper(II) Tetraphenylborate

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    The crystal structure (P21/c, a = 1199.7(2), b = 1304.2(4), c = = 1639.1(4) pm, beta = 102.10(1) 0 (J.. MoKa = 71.069 pm), Z = 2) of this compound, [CuC14H24N4] [B(C5Hs)4]2, has been determined from diffractometer x-ray data and refined by least-squares to R = 0.055 and Rw = 0.037. The CuTIM cation, planar except for two methylene groups, is one of the rare cases of planar four-coordinate copper(II), although the apical regions of the coordination sphere are occupied by the centers of phenyf groups from two tetraphenylborate ions. The tetraphenylborate ion has a normal conformation which deviates slightly, but significantly, from S4 symmetry

    The Crystal Structure of (2,3,9,10-tetramethyl-1,4,8,11-tetraaza- 1,3,8, 10-cyclotetradecatetraene )copper(II) Tetraphenylborate

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    The crystal structure (P21/c, a = 1199.7(2), b = 1304.2(4), c = = 1639.1(4) pm, beta = 102.10(1) 0 (J.. MoKa = 71.069 pm), Z = 2) of this compound, [CuC14H24N4] [B(C5Hs)4]2, has been determined from diffractometer x-ray data and refined by least-squares to R = 0.055 and Rw = 0.037. The CuTIM cation, planar except for two methylene groups, is one of the rare cases of planar four-coordinate copper(II), although the apical regions of the coordination sphere are occupied by the centers of phenyf groups from two tetraphenylborate ions. The tetraphenylborate ion has a normal conformation which deviates slightly, but significantly, from S4 symmetry

    A HPMT based set-up to characterize scintillating crystals

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    We have developed a fully automatic measurement set-up, capable of measuring light yields arising from scintillating crystals in a linear range of about four orders of magnitude. The photodetector is a Hybrid Photomultiplier Tube especially developed to optimize linear range and photon detection. Crystal and photodetector are temperature controlled by a closed water circuit, as this is essential when measuring low light yield scintillating crystals with a marked temperature dependence of their light yield. Gamma sources can be placed either on top or on the side of the crystal. In this latter case, the source can be automatically moved by a computer-controlled step motor to provide a uniformity profile of the light yield along the crystal. Tagged and not-tagged operation modes are possible. The whole set-up is computer-controlled in an effort to provide fast and reliable measurements, to characterize many crystals per day. This is important for the quality control of the Lead Tungstate crystals that will be applied in the electromagnetic calorimeter of the CMS-detector at the LHC at CERN

    Mortality in patients with HIV-1 infection starting antiretroviral therapy in South Africa, Europe, or North America: a collaborative analysis of prospective studies

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    Analyzing survival in HIV treatment cohorts, Andrew Boulle and colleagues find mortality rates in South Africa comparable to or better than those in North America by 4 years after starting antiretroviral therapy. Please see later in the article for the Editors' Summar

    Baseline Predictors of Sputum Culture Conversion in Pulmonary Tuberculosis: Importance of Cavities, Smoking, Time to Detection and W-Beijing Genotype

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    Background: Time to detection (TTD) on automated liquid mycobacterial cultures is an emerging biomarker of tuberculosis outcomes. The M. tuberculosis W-Beijing genotype is spreading globally, indicating a selective advantage. There is a paucity of data on the association between baseline TTD and W-Beijing genotype and tuberculosis outcomes. Aim: To assess baseline predictors of failure of sputum culture conversion, within the first 2 months of antitubercular therapy, in participants with pulmonary tuberculosis. Design: Between May 2005 and August 2008 we conducted a prospective cohort study of time to sputum culture conversion in ambulatory participants with first episodes of smear and culture positive pulmonary tuberculosis attending two primary care clinics in Cape Town, South Africa. Rifampicin resistance (diagnosed on phenotypic susceptibility testing) was an exclusion criterion. Sputum was collected weekly for 8 weeks for mycobacterial culture on liquid media (BACTEC MGIT 960). Due to missing data, multiple imputation was performed. Time to sputum culture conversion was analysed using a Cox-proportional hazards model. Bayesian model averaging determined the posterior effect probability for each variable. Results: 113 participants were enrolled (30.1% female, 10.5% HIV-infected, 44.2% W-Beijing genotype, and 89% cavities). On Kaplan Meier analysis 50.4% of participants underwent sputum culture conversion by 8 weeks. The following baseline factors were associated with slower sputum culture conversion: TTD (adjusted hazard ratio (aHR) = 1.11, 95% CI 1.02; 1.2), lung cavities (aHR = 0.13, 95% CI 0.02; 0.95), ever smoking (aHR = 0.32, 95% CI 0.1; 1.02) and the W-Beijing genotype (aHR = 0.51, 95% CI 0.25; 1.07). On Bayesian model averaging, posterior probability effects were strong for TTD, lung cavitation and smoking and moderate for W-Beijing genotype. Conclusion: We found that baseline TTD, smoking, cavities and W-Beijing genotype were associated with delayed 2 month sputum culture. Larger studies are needed to confirm the relationship between the W-Beijing genotype and sputum culture conversion.Publisher's versio

    Eco-bio-social determinants for house infestation by non-domiciliated Triatoma dimidiata in the Yucatan peninsula, Mexico

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    Background Chagas disease is a vector-borne disease of major importance in the Americas. Disease prevention is mostly limited to vector control. Integrated interventions targeting ecological, biological and social determinants of vector-borne diseases are increasingly used for improved control. Methodology/principal findings We investigated key factors associated with transient house infestation by T. dimidiata in rural villages in Yucatan, Mexico, using a mixed modeling approach based on initial null-hypothesis testing followed by multimodel inference and averaging on data from 308 houses from three villages. We found that the presence of dogs, chickens and potential refuges, such as rock piles, in the peridomicile as well as the proximity of houses to vegetation at the periphery of the village and to public light sources are major risk factors for infestation. These factors explain most of the intra-village variations in infestation. Conclusions/significance These results underline a process of infestation distinct from that of domiciliated triatomines and may be used for risk stratification of houses for both vector surveillance and control. Combined integrated vector interventions, informed by an Ecohealth perspective, should aim at targeting several of these factors to effectively reduce infestation and provide sustainable vector control

    Novelty Enhances Visual Perception

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    The effects of novelty on low-level visual perception were investigated in two experiments using a two-alternative forced-choice tilt detection task. A target, consisting of a Gabor patch, was preceded by a cue that was either a novel or a familiar fractal image. Participants had to indicate whether the Gabor stimulus was vertically oriented or slightly tilted. In the first experiment tilt angle was manipulated; in the second contrast of the Gabor patch was varied. In the first, we found that sensitivity was enhanced after a novel compared to a familiar cue, and in the second we found sensitivity to be enhanced for novel cues in later experimental blocks when participants became more and more familiarized with the familiar cue. These effects were not caused by a shift in the response criterion. This shows for the first time that novel stimuli affect low-level characteristics of perception. We suggest that novelty can elicit a transient attentional response, thereby enhancing perception

    Crystal structure of the ferritin from the hyperthermophilic archaeal anaerobe Pyrococcus furiosus

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    The crystal structure of the ferritin from the archaeon, hyperthermophile and anaerobe Pyrococcus furiosus (PfFtn) is presented. While many ferritin structures from bacteria to mammals have been reported, until now only one was available from archaea, the ferritin from Archaeoglobus fulgidus (AfFtn). The PfFtn 24-mer exhibits the 432 point-group symmetry that is characteristic of most ferritins, which suggests that the 23 symmetry found in the previously reported AfFtn is not a common feature of archaeal ferritins. Consequently, the four large pores that were found in AfFtn are not present in PfFtn. The structure has been solved by molecular replacement and refined at 2.75-Å resolution to R = 0.195 and Rfree = 0.247. The ferroxidase center of the aerobically crystallized ferritin contains one iron at site A and shows sites B and C only upon iron or zinc soaking. Electron paramagnetic resonance studies suggest this iron depletion of the native ferroxidase center to be a result of a complexation of iron by the crystallization salt. The extreme thermostability of PfFtn is compared with that of eight structurally similar ferritins and is proposed to originate mostly from the observed high number of intrasubunit hydrogen bonds. A preservation of the monomer fold, rather than the 24-mer assembly, appears to be the most important factor that protects the ferritin from inactivation by heat

    Why and how does shared language affect subsidiary knowledge inflows? A social identity perspective

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    We draw on social identity theory to conceptualize a moderated mediation model that examines the relationship between shared language among subsidiary and HQ managers, and subsidiaries’ knowledge inflows from HQ. Specifically, we study (1) whether this relationship is mediated by the extent to which subsidiary managers share HQ goals and vision, and the extent to which HR decisions are centralized; and (2) whether subsidiary type moderates these mediated relationships. Building on a sample of 817 subsidiaries in nine countries/regions, we find support for our model. Implications for research on HQ-subsidiary knowledge flows, social identity theory and international HRM are discussed
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