20,700 research outputs found

    \u3cem\u3eIllicit Drug Policies, Trafficking and Use the World Over.\u3c/em\u3e Cathrina Gouvis Roman, Heather Ahn-Redding and Rita J. Simon.

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    Book note for Caterina Gouvis Roman, Heather Ahn-Redding and Rita J. Simon, Illicit Drug Policies, Trafficking, and Use the World Over. Lanham, MD: Rowman & Littlefield, 2005, $75.00 hardcover

    A note on constrained degree reduction of polynomials in Bernstein–BĂ©zier form over simplex domain

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    AbstractIn the paper [H.S. Kim, Y.J. Ahn, Constrained degree reduction of polynomials in Bernstein–BĂ©zier form over simplex domain, J. Comput. Appl. Math. 216 (2008) 14–19], Kim and Ahn proved that the best constrained degree reduction of a polynomial over d-dimensional simplex domain in L2-norm equals the best approximation of weighted Euclidean norm of the Bernstein–BĂ©zier coefficients of the given polynomial. In this paper, we presented a counterexample to show that the approximating polynomial of lower degree to a polynomial is virtually non-existent when d≄2. Furthermore, we provide an assumption to guarantee the existence of solution for the constrained degree reduction

    Enhancing adult hippocampal neurogenesis with lysophosphatidic acid: a proposal for erasing cocaine contextual memory

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    Stimulating adult hippocampal neurogenesis (AHN) has been uncovered as a promising approach in the manipulation of retrograde memories. This work aims to study whether increasing AHN with lysophosphatidic acid (LPA, an endogenous lysophospholipid with proneurogenic actions) promotes the forgetting of previously established cocaine-contextual associations. C57BL/6J mice previously trained in a cocaine-induced conditioned place preference (CPP) paradigm were submitted to 23 days of withdrawal, during which they received repeated intracerebroventricular infusions of LPA, ki16425 (a selective LPA1/3 receptors antagonist), or vehicle solution. Then, CPP maintenance was assessed, and the causal role of AHN in this process was evaluated using a mediation analysis. In a complementary experiment, wild-type and LPA1-null mice were acutely infused with LPA or ki16425 to determine the involvement of the LPA1 receptor in the in vivo proneurogenic actions of LPA. The chronic LPA treatment significantly weakened the long-term retention of a previously acquired cocaine-CPP memory, an effect clearly mediated by a LPA-induced increase in the number of adult-born dentate granule cells. In contrast, the ki16425-treated mice displayed aberrant responses of initially decreased CPP retention that progressively increased CPP across the extinction sessions, in absence of effects on AHN. The histological studies suggested that the proneurogenic actions of LPA were related to the enhancement of cell proliferation and critically depended on the LPA1 receptor function. Our results suggest that the LPA/LPA1-pathway acts as a potent in vivo modulator of AHN, and highlight the usefulness of a post-learning increase of adult-born hippocampal neurons as a strategy to promote the forgetting of cocaine-context associations.Plan Propio de Investigación y Transferencia. Campus de Excelencia Internacional Andalucía Tech. Spanish Ministry of Economy and Competitiveness (Agencia Estatal de Investigación), co‐funded by the European Research Development Fund (AEI/FEDER, UE) (PSI2013‐44901‐P and PSI2017‐82604‐R to L.J.S. and PSI2015‐73156‐JIN to E.C.O.); by the National System of Health‐Instituto de Salud Carlos III, which is co‐funded by AEI/FEDER, UE (Red de Trastornos Adictivos; RD16/0017/0001 to F.R.d.F.); and by the Andalusian R&D&I Programme, Regional Ministry of Economy and Knowledge (PAIDI CTS643 to G.E.T.). D.L.G.M. hold a FPU grant from the Spanish Ministry of Education, Culture and Sports (FPU13/04819 ). F.R.d.F. and G.E.T. are supported by Nicolas Monardes Programme, from the Andalusian Regional Ministry of Health. E.C.O. holds a ‘Jóvenes Investigadores’ grant (code: PSI2015‐73156‐JIN) from the Spanish Ministry of Economy and Competitiveness (Agencia Estatal de Investigación), which is co‐funded by the AEI/FEDER, UE

    Note on the Origin of the Highest Energy Cosmic Rays

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    In this note we argue that the galactic model chosen by E.-J. Ahn, G. Medina-Tanco, P.L. Bierman and T. Stanev in their paper discussing the origin of the highest energy cosmic rays, is alone responsible for the focussing of positive particles towards the North galactic pole. We discuss the validity of this model, in particular in terms of field reversals and radial extensions. We conclude that with such a model one cannot retreive any directional information from the observed direction of the cosmic rays. In particular one cannot identify point sources at least up to energies of about 200 EeV. Therefore the apparent clustering of the back-traced highest energy cosmic rays observed to date cannot be interpreted as an evidence for a point source nor for the identification of M87, which happens to be close to the North pole, as being such a source.Comment: 3 pages, 2 figure

    Artificial Respiration and AHN: Some Similarities and Differences

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    Effects of sequential exposure to physical exercise and cognitive training on hippocampal neurogenesis in mice

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    AIMS: Physical exercise and cognitive training hippocampal dependent tasks are known to enhance adult hippocampal neurogenesis (AHN). Here we aimed to evaluate the effect of either a moderate-intensity exercise protocol, a working memory task and the combination of both treatments on mice AHN. METHODS: Adult male C57BL6/J mice (N=34) were submitted to a scheduled treadmill exercise protocol for 12 days (EX-groups) or remained at home cage (SED-groups). 24 hours later, animals either were perfused or trained in a spatial learning task in the Water Maze (WM groups) for 8 days while control groups remained at home cage (CAGE groups). Bromodeoxyuridine (BrdU) was injected at the beginning of every experimental procedure to label hippocampal cells that proliferated during the initial exercise sessions. RESULTS: Mice submitted to scheduled exercise showed an increased number of BrdU+ and PCNA+ dentate granule cells (DGCs) in the short but not in the long-term when compared to sedentary groups. Conversely, training in the WM solely reduced the amount of BrdU+ and PCNA+ DGCs compared to CAGE group. However, animals submitted to scheduled exercise and WM training showed increased proliferation/survival of DGCs in the long-term compared to all other groups. CONCLUSIONS: Our data suggests that the combination of moderate-intensity exercise with spatial training has a powerful neurogenic effect in the DG, being a valuable non-pharmacological strategy for the treatment of neurodegenerative diseases associated with impaired AHN. Funding: PSI2017-82604; PRE2018-085673; FPU20/00908; 08-2021-AREA3; B1-2020_06; Posdoc_21_00222; Posdoctoral_a32. I Plan Propio de InvestigaciĂłn, Transferencia y DivulgaciĂłn CientĂ­fica de la Universidad de MĂĄlaga.Universidad de MĂĄlaga. Campus de Excelencia Internacional AndalucĂ­a Tech

    Training memory without aversion: Appetitive hole-board spatial learning increases adult hippocampal neurogenesis.

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    Learning experiences are potent modulators of adult hippocampal neurogenesis (AHN). However, the vast majority of findings on the learning-induced regulation of AHN derive from aversively-motivated tasks, mainly the water maze paradigm, in which stress is a confounding factor that affects the AHN outcome. Currently, little is known regarding the effect of appetitively-motivated training on AHN. Hence we studied how spatial learning to find food rewards in a hole-board maze modulates AHN (cell proliferation and immature neurons) and AHN-related hippocampal neuroplasticity markers (BDNF, IGF-II and CREB phosphorylation) in mice. The 'Trained' mice were tested for both spatial reference and working memory and compared to 'Pseudotrained' mice (exposed to different baited holes in each session, thus avoiding the reference memory component of the task) and 'Control' mice (exposed to the maze without rewards). In contrast to Pseudotrained and Control mice, Trained mice reduced the number of proliferating hippocampal cells but they notably increased their population of immature neurons assessed by immunohistochemistry. This evidence shows that hole-board spatial reference learning diminishes cell proliferation in favor of enhancing young neurons' survival. Interestingly, the enhanced AHN in the Trained mice (specifically in the suprapyramidal blade) positively correlated with their reference memory performance, but not with their working memory. Furthermore, the Trained animals increased the hippocampal protein expression of all the neuroplasticity markers analyzed by western blot. Results show that the appetitively-motivated hole-board task is an useful paradigm to potentiate and/or investigate AHN and hippocampal plasticity minimizing aversive variables such as fear or stress.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. This study was funded by grants from the Spanish Ministry of Economy and Competitiveness (Agencia Estatal de Investigación) co-funded by the European Research Development Fund -AEI/FEDER, UE- (PSI2015-73156-JIN ‘Jóvenes Investigadores grant’ to E.C.O. and PSI2013-44901-P to L.J.S. and C.P.), from ‘Junta de Andalucía’ SEJ1863 to C.P. and from University of Málaga (Plan Propio 2017 – ‘Ayudas para proyectos puente’) to M.G.F. Author P.S.P. holds a ‘Juan de la Cierva-formación‘grant from the Spanish Ministry of Economy, Industry and Competitiveness (code: FJCI-2015-23925) and a ‘D.3. Estancia de investigadores de reconocido prestigio en la UMA‘ grant from the University of Málaga. Authors R.D.M.F. and D.L.G.M. hold ‘FPU’ grants from the Spanish Ministry of Education, Culture and Sports (code: FPU14-01610 and FPU13/04819, respectively). Author F.J.P. holds a ‘Miguel Servet’ grant (code: CP14/00212) from the National System of Health-Instituto de Salud Carlos-III co-funded by FEDER, UE

    Solution-processed organic devices developed by a novel cost-effective patterning technique based on electrical erosion

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    Application of arc erosion to the patterning of metallic contacts in organic devices is presented. A home-made systems and details of the working principles are described. Advantages and drawbacks of this novel technology are discussed
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