386 research outputs found

    Applications of surficial mapping to forest management in New Brunswick

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    Joint investigations of the Geological Surveys (G.S.B.) and Timber Management (T.M.B.) branches of the New Brunswick Department of Natural Resources and Energy during the past ten years have demonstrated a well-defined relationship between forest productivity for different species with several geologic and climatic parameters. A method referred to as regolith mapping developed by the G.S.B. has enabled the T.M.B. to evaluate these geologic parameters in forest productivity. The growth curves for certain tree species on soils that formed on different regolith systems are discussed. The results of this work have been incorporated in long-term forest management plans. RÉSUMÉ Les études conjointes menĂ©es par les divisions des études géologiques et de l'amĂ©nagement du bo is du Ministere des Ressources Narurelles et de l'Énergie du Nouveau-Brunswick durant les dix dernieres annĂ©es ont montré une rélation bien définie entre la productivity forestiere de différentés espèces et plusieurs paramétres gĂ©ologiques et climatiques. Une méthode, appelée la cartographic du rĂ©golite et développĂ©e par la division des études géologiques, à permis à la division de l'amenagement du bois d'évaluer les parametres géologiques relief à la productivity forestiere. Les courbes de croissance de certaines especes d'arbres poussant sur des sols dĂ©veloppĂ©s sur différents régolites sont discuses. Les résultats de cette étude ont été incorpords dans les plans de gestion forestière à long terme. [Traduit par le journal

    Microglia modulate hippocampal neural precursor activity in response to exercise and aging

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    Exercise has been shown to positively augment adult hippocampal neurogenesis; however, the cellular and molecular pathways mediating this effect remain largely unknown. Previous studies have suggested that microglia may have the ability to differentially instruct neurogenesis in the adult brain. Here, we used transgenic Csf1r-GFP mice to investigate whether hippocampal microglia directly influence the activation of neural precursor cells. Our results revealed that an exercise-induced increase in neural precursor cell activity was mediated via endogenous microglia and abolished when these cells were selectively removed from hippocampal cultures. Conversely, microglia from the hippocampi of animals that had exercised were able to activate latent neural precursor cells when added to neurosphere preparations from sedentary mice. We also investigated the role of CX(3)CL1, a chemokine that is known to provide a more neuroprotective microglial phenotype. Intraparenchymal infusion of a blocking antibody against the CX(3)CL1 receptor, CX(3)CR1, but not control IgG, dramatically reduced the neurosphere formation frequency in mice that had exercised. While an increase in soluble CX(3)CL1 was observed following running, reduced levels of this chemokine were found in the aged brain. Lower levels of CX(3)CL1 with advancing age correlated with the natural decline in neural precursor cell activity, a state that could be partially alleviated through removal of microglia. These findings provide the first direct evidence that endogenous microglia can exert a dual and opposing influence on neural precursor cell activity within the hippocampus, and that signaling through the CX(3)CL1-CX(3)CR1 axis critically contributes toward this process

    Transdiagnostic factors predicting the 2-year disability outcome in patients with anxiety and depressive disorders

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    Background: Both anxiety and depressive disorders are associated with significant long-term disability. Since experienced impairments vary between patients independent of diagnosis and disease severity, identifying transdiagnostic factors that predict the course of disability may provide new targets to reduce disability. This study examines transdiagnostic factors predicting the 2-year disability outcome in patients with anxiety and/or depressive disorders (ADD), focusing on potentially malleable factors.Methods: Six hundred fifteen participants with a current diagnosis of ADD from the Netherlands Study of Depression and Anxiety (NESDA) were included. Disability was assessed at baseline and after 2 years of follow-up, using the 32-item WHODAS II questionnaire. Transdiagnostic predictors of 2-year disability outcome were identified using linear regression analysis.Results: In univariable analyses, transdiagnostic factors associated with the 2-year disability outcome were locus of control (standardized β = -0.116, p = 0.011), extraversion (standardized β = -0.123 p = 0.004) and experiential avoidance (standardized β = 0.139, p = 0.001). In multivariable analysis, extraversion had a unique predictive value (standardized β = -0.143 p = 0.003). A combination of sociodemographic, clinical and transdiagnostic variables resulted in an explained variance (R2) of 0.090). The explained variance of a combination of transdiagnostic factors was 0.050.Conclusion: The studied transdiagnostic variables explain a small but unique part of variability in the 2-year disability outcome. Extraversion is the only malleable transdiagnostic factor predictive of the course of disability independent of other variables. Due to the small contribution to the variance in the disability outcome, the clinical relevance of targeting extraversion seems limited. However, its predictive value is comparable to that of accepted disease severity measures, supporting the importance of looking beyond using disease severity measures as predictors. Furthermore, studies including extraversion in combination with other transdiagnostic and environmental factors may elucidate the unexplained part of variability of the course of disability in patients with ADD.</p

    Ex vivo adenoviral vector-mediated neurotrophin gene transfer to olfactory ensheathing glia: Effects on rubrospinal tract regeneration, lesion size, and functional recovery after implantation in the injured rat spinal cord

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    The present study uniquely combines olfactory ensheathing glia (OEG) implantation with ex vivo adenoviral (AdV) vector-based neurotrophin gene therapy in an attempt to enhance regeneration after cervical spinal cord injury. Primary OEG were transduced with AdV vectors encoding rat brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), or bacterial marker protein -galactosidase (LacZ) and subsequently implanted into adult Fischer rats directly after unilateral transection of the dorsolateral funiculus. Implanted animals received a total of 2 x 105 OEG that were subjected to transduction with neurotrophin-encoding AdV vector, AdV-LacZ, or no vector, respectively. At 4 months after injury, lesion volumes were smaller in all OEG implanted rats and significantly reduced in size after implantation of neurotrophin-encoding AdV vector-transduced OEG. All OEG grafts were filled with neurofilament-positive axons, and AdV vector-mediated expression of BDNF by implanted cells significantly enhanced regenerative sprouting of the rubrospinal tract. Behavioral analysis revealed that OEG-implanted rats displayed better locomotion during horizontal rope walking than unimplanted lesioned controls. Recovery of hind limb function was also improved after implantation of OEG that were transduced with a BDNF- or NT-3-encoding AdV vector. Hind limb performance during horizontal rope locomotion did directly correlate with lesion size, suggesting that neuroprotective effects of OEG implants contributed to the level of functional recovery. Thus, our results demonstrate that genetic engineering of OEG not only resulted in a cell that was more effective in promoting axonal outgrowth but could also lead to enhanced recovery after injury, possibly by sparing of spinal tissue

    Master-equation approach to the study of phase-change processes in data storage media

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    We study the dynamics of crystallization in phase-change materials using a master-equation approach in which the state of the crystallizing material is described by a cluster size distribution function. A model is developed using the thermodynamics of the processes involved and representing the clusters of size two and greater as a continuum but clusters of size one (monomers) as a separate equation. We present some partial analytical results for the isothermal case and for large cluster sizes, but principally we use numerical simulations to investigate the model. We obtain results that are in good agreement with experimental data and the model appears to be useful for the fast simulation of reading and writing processes in phase-change optical and electrical memories

    Immature doublecortin-positive hippocampal neurons are important for learning but not for remembering

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    It is now widely accepted that hippocampal neurogenesis underpins critical cognitive functions, such as learning and memory. To assess the behavioral importance of adult-born neurons, we developed a novel knock-in mouse model that allowed us to specifically and reversibly ablate hippocampal neurons at an immature stage. In these mice, the diphtheria toxin receptor (DTR) is expressed under control of the doublecortin (DCX) promoter, which allows for specific ablation of immature DCX-expressing neurons after administration of diphtheria toxin while leaving the neural precursor pool intact. Using a spatially challenging behavioral test (a modified version of the active place avoidance test), we present direct evidence that immature DCX-expressing neurons are required for successful acquisition of spatial learning, as well as reversal learning, but are not necessary for the retrieval of stored long-term memories. Importantly, the observed learning deficits were rescued as newly generated immature neurons repopulated the granule cell layer upon termination of the toxin treatment. Repeat (or cyclic) depletion of immature neurons reinstated behavioral deficits if the mice were challenged with a novel task. Together, these findings highlight the potential of stimulating neurogenesis as a means to enhance learning

    The ferric leaching kinetics of arsenopyrite

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    Abstract In this investigation batch, ferric leaching experiments were carried out in a 100 m l l jacketed vessel maintained at 258C. The parameters varied during the course of the experimental program included the initial redox potential, the total iron concentration, the solids concentration and the pH of the leaching solution. The initial redox potential used ranged from 625 to 470 mV, the overall iron concentration ranged from 8 to 32 g. l l y1 , the mineral concentration ranged from 5 to 20 g. l l y1 and the initial pH used ranged from 1.10 to 1.45. The redox potential of the leach solution was monitored continuously using a redox probe connected to a computer. The leach rates were calculated from the measured change in the redox potential of the leaching solution. The variation in the ferric leaching rate of the arsenopyrite as a function of the solution redox potential displayed similar trends, irrespective of the conditions employed. The ferric leaching rate of the arsenopyrite decreased with decreasing redox potential of the leaching solution and could be accurately described using a modified Butler-Volmer equation; yr s r e y . High concentrations of ferric iron and protons, and a reduction in the solids Ĺ˝ concentration were found to impede the leach rate. The &apos;rest potential&apos; i.e., the redox potential at . which the dissolution of arsenopyrite stops of the arsenopyrite was found to be higher under these conditions. However, no occluding sulphur layer could be detected on the surface of mineral particles, hence the results suggest that the reactivity of the mineral decreases with an increase in the effective concentration of the ferric iron species. Therefore, although the results suggest the Ĺ˝ . PII: S 0 3 0 4 -3 8 6 X 9 9 0 0 0 0 7 -9 ( ) R. Ruitenberg et al.r Hydrometallurgy 52 1999 37-53 38 likelihood of an electrochemical mechanism being operative, it is necessary to modify the Butler-Volmer-based model to account for the above observations in order to obtain a model capable of predicting the ferric leaching rate of arsenopyrite across a broad range of operating conditions.

    Experimental loophole-free violation of a Bell inequality using entangled electron spins separated by 1.3 km

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    For more than 80 years, the counterintuitive predictions of quantum theory have stimulated debate about the nature of reality. In his seminal work, John Bell proved that no theory of nature that obeys locality and realism can reproduce all the predictions of quantum theory. Bell showed that in any local realist theory the correlations between distant measurements satisfy an inequality and, moreover, that this inequality can be violated according to quantum theory. This provided a recipe for experimental tests of the fundamental principles underlying the laws of nature. In the past decades, numerous ingenious Bell inequality tests have been reported. However, because of experimental limitations, all experiments to date required additional assumptions to obtain a contradiction with local realism, resulting in loopholes. Here we report on a Bell experiment that is free of any such additional assumption and thus directly tests the principles underlying Bell's inequality. We employ an event-ready scheme that enables the generation of high-fidelity entanglement between distant electron spins. Efficient spin readout avoids the fair sampling assumption (detection loophole), while the use of fast random basis selection and readout combined with a spatial separation of 1.3 km ensure the required locality conditions. We perform 245 trials testing the CHSH-Bell inequality S≤2S \leq 2 and find S=2.42±0.20S = 2.42 \pm 0.20. A null hypothesis test yields a probability of p=0.039p = 0.039 that a local-realist model for space-like separated sites produces data with a violation at least as large as observed, even when allowing for memory in the devices. This result rules out large classes of local realist theories, and paves the way for implementing device-independent quantum-secure communication and randomness certification.Comment: Raw data will be made available after publicatio

    Comparison of NITAG policies and working processes in selected developed countries

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    BACKGROUND: Vaccines are specific medicines characterized by two country-specific market access processes: (1) a recommendation by National Immunization Technical Advisory Group (NITAG), and (2) a funding policy decision. OBJECTIVES: The objective of this study was to compare and analyze NITAGs of 13 developed countries by describing vaccination committees' bodies and working processes. METHODS: Information about NITAGs bodies and working processes was searched from official sources from June 2011 to November 2012. Retrieved information was completed from relevant articles identified through a systematic literature review and by information provided by direct contact with NITAGs or parent organizations. An expert panel was also conducted to discuss, validate, and provide additional input on obtained results. RESULTS: While complete information, defined as 100%, was retrieved only for the UK, at least 80% of data was retrieved for 9 countries out of the 13 selected countries. Terms of references were identified in 7 countries, and the main mission for all NITAGs was to provide advice for National immunization programs. However, these terms of references did not fully encompass all the actual missions of the NITAGs. Decision analysis frameworks were identified for 10 out of the 13, and all NITAGs considered at least four criteria for decision-making: disease burden, efficacy/effectiveness, safety and cost-effectiveness. Advices were published by most NITAGs, but few NITAGs published meeting agendas and minutes. Only the United States had open meetings. CONCLUSIONS: This study supports previous findings about the disparities in NITAGs processes which could potentially explain the disparity in access to vaccinations and immunization programs across Europe. With NITAGs recommendations being used by policy decision makers for implementation and funding of vaccine programs, guidances should be well-informed and transparent to ensure National Immunization Programs' (NIP) credibility among the public and health care professionals
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