362 research outputs found

    Understanding of the Retarded Oxidation Effects in Silicon Nanostructures

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    In-depth understanding of the retarded oxidation phenomenon observed during the oxidation of silicon nanostructures is proposed. The wet thermal oxidation of various silicon nanostructures such as nanobeams, concave/convex nanorings and nanowires exhibits an extremely different and complex behavior. Such effects have been investigated by the modeling of the mechanical stress generated during the oxidation process explaining the retarded regime. The model describes the oxidation kinetics of silicon nanowires down to a few nanometers while predicting reasonable and physical stress levels at the Si/SiO2_{2} interface by correctly taking into account the relaxation effects in silicon oxide through plastic flow

    Online Model Server for the Jefferson Lab accelerator

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    A beam physics model server (Art++) has been developed for the Jefferson Lab accelerator. This online model server is a redesign of the ARTEMIS model server. The need arose from an impedance mismatch between the current requirements and ARTEMIS capabilities. The purpose of the model server is to grant access to both static (machine lattice parameters) and dynamic (actual machine settings) data using a single programming interface. A set of useful optics calculations (R-matrix, orbit fit, etc.) has also been implemented and can be invoked by clients via the model interface. Clients may also register their own dynamic models in the server. The server interacts with clients using the CDEV protocol and data integrity is guaranteed by a relational database (Oracle8i) accessed through a persistence layer. By providing a centralized repository for both data and optics calculations, the following benefits were achieved: optimal use of network consumption, software reuse, and ease of maintenance

    L’Indice de biodiversité potentielle (IBP) en région méditerranéenne

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    L’IBP est un outil pour évaluer la biodiversité taxonomique ordinaire des peuplements forestiers. Rapide et simple à utiliser, il est basé sur l’estimation indirecte de la biodiversité au travers de l’évaluation de la capacité d’accueil en espèces et en communautés, à l’échelle du peuplement forestier. Il consiste à apprécier un ensemble de dix facteurs parmi ceux qui sont habituellement reconnus comme les plus favorables à la diversité interne des peuplements. Un score de 0, 2 ou 5 est donné sur le terrain à chacun des facteurs selon une échelle de valeurs seuils et leur somme donne l’IBP. L’IBP est adapté à toutes les forêts des domaines atlantique et continental. L’extension à la région méditerranéenne est à l’étude depuis 2009. Le domaine d’utilisation de l’IBP « méditerranée » a été précisé, tant au niveau géographique qu’au niveau des formations végétales concernées. Les facteurs et les seuils ont été revus pour tenir compte des caractéristiques des forêts méditerranéennes. La problématique des incendies est également étudiée à travers les relations entre la biodiversité taxonomique et les feux de forêt, car la forêt méditerranéenne est particulièrement concernée

    Modelling the probability of microhabitat formation on trees using cross-sectional data

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    The rate of TreM formation per unit diameter growth was modelled as a function of tree diameter at breast height (DBH), and the model was calibrated considering cross-sectional observations TreMs on trees of different sizes. The model predicted realistic TreM formation rates at the tree and stand levels in forests dominated by Abies alba and Fagus sylvatica. This approach opens new perspectives to the analysis of forest biodiversity conservation strategies

    Challenges in dengue research: A computational perspective

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    This is the final version of the article. Available from Wiley via the DOI in this record.The dengue virus is now the most widespread arbovirus affecting human populations, causing significant economic and social impact in South America and South-East Asia. Increasing urbanization and globalization, coupled with insufficient resources for control, misguided policies or lack of political will, and expansion of its mosquito vectors are some of the reasons why interventions have so far failed to curb this major public health problem. Computational approaches have elucidated on dengue's population dynamics with the aim to provide not only a better understanding of the evolution and epidemiology of the virus but also robust intervention strategies. It is clear, however, that these have been insufficient to address key aspects of dengue's biology, many of which will play a crucial role for the success of future control programmes, including vaccination. Within a multiscale perspective on this biological system, with the aim of linking evolutionary, ecological and epidemiological thinking, as well as to expand on classic modelling assumptions, we here propose, discuss and exemplify a few major computational avenues—real-time computational analysis of genetic data, phylodynamic modelling frameworks, within-host model frameworks and GPU-accelerated computing. We argue that these emerging approaches should offer valuable research opportunities over the coming years, as previously applied and demonstrated in the context of other pathogens.JL, AW and SG received funding from the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013) / ERC grant agreement no. 268904 - DIVERSITY. MR was supported by a Royal Society University Research Fellowship. NRF by a Sir Henry Dale Fellowship jointly funded by the Wellcome Trust and the Royal Society (grant number 204311/Z/16/Z). WT has received funding from a doctoral scholarship from the Engineering and Physical Sciences Research Council (EPSRC) Doctoral Training Partnership

    Nutritional omega-3 deficiency alters glucocorticoid receptor-signaling pathway and neuronal morphology in regionally distinct brain structures associated with emotional deficits

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    Extensive evidence suggests that long term dietary n-3 polyunsaturated fatty acids (PUFAs) deficiency results in altered emotional behaviour. We have recently demonstrated that n-3 PUFAs deficiency induces emotional alterations through abnormal corticosterone secretion which leads to altered dendritic arborisation in the prefrontal cortex (PFC). Here we show that hypothalamic-pituitary-adrenal (HPA) axis feedback inhibition was not compromised in n-3 deficient mice. Rather, glucocorticoid receptor (GR) signaling pathway was inactivated in the PFC but not in the hippocampus of n-3 deficient mice. Consequently, only dendritic arborisation in PFC was affected by dietary n-3 PUFAs deficiency. In addition, occlusion experiment with GR blockade altered GR signaling in the PFC of control mice, with no further alterations in n-3 deficient mice. In conclusion, n-3 PUFAs deficiency compromised PFC, leading to dendritic atrophy, but did not change hippocampal GR function and dendritic arborisation. We argue that this GR sensitivity contributes to n-3 PUFAs deficiency-related emotional behaviour deficits

    Disponibilidad y relación de calcio y magnesio

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    Ca and Mg are involved in plant growth according to their availability, and possibly their relationship. The soils of the Pampean Region have been considered well endowed with these elements, although they diagnosed areas with low contents. The objective of this work was to evaluate different concentrations of Ca in nutrient solution on the production of dry matter (DM), Ca and Mg content in DM, and its annual export in annual ryegrass (Lolium multiflorum L.) and forage soybean (Glycine max [L.] Merr). Additionally, the effect of doubling the concentration at the same Ca/Mg ratio was evaluated. A test was carried out with nutrient solutions of 1, 5, 9 and 12 mM Ca and 2 mM Mg. A treatment with 10 mM Ca and 4 mM Mg was added. Three cuts were made in ryegrass and one in soybeans. In ryegrass, it was determined that the levels of calcium nutrition influence the concentrations and export of Ca and Mg in MS, without effects on the production of DM. The Ca/Mg ratio was occasionally related to the concentration of Ca and Mg in MS and in the export of Ca and Mg. In soybean, calcium nutrition levels influence the production of DM, concentrations of Ca in DM and the export of Ca and Mg, while they do not intervene in the concentration of Mg in DM. The Ca/Mg ratio in solution occasionally had an effect on the concentration of Ca in MS and on the export of Ca and Mg.El Ca y el Mg intervienen en el crecimiento vegetal según su disponibilidad, y posiblemente su relación. Los suelos de la Región Pampeana se han considerado bien dotados de estos elementos, aunque diagnosticaron áreas con bajos contenidos. El objetivo del trabajo fue evaluar diferentes concentraciones de Ca en solución nutritiva sobre la producción de materia seca (MS), contenido de Ca y Mg en MS, y su exportación aérea en raigrás anual (Lolium multiflorum L.) y soja forrajera (Glycine max [L.] Merr). Adicionalmente, se evaluó el efecto de duplicar la concentración a igual relación Ca/Mg. Se realizó un ensayo con soluciones nutritivas de 1, 5, 9 y 12 mM Ca y 2 mM Mg. Se adicionó un tratamiento con 10 mM Ca y 4 mM Mg. Se realizaron tres cortes en raigrás y uno en soja. Se determinó que en raigrás los niveles de nutrición cálcica influyen sobre las concentraciones y exportación de Ca y Mg en MS, sin efectos sobre la producción de MS. La relación Ca/Mg ocasionalmente se relacionó con la concentración de Ca y Mg en MS y en la exportación de Ca y Mg. En soja, los niveles de nutrición cálcica influyen sobre la producción de MS, concentraciones de Ca en MS y en la exportación de Ca y Mg, mientras que no intervienen en la concentración de Mg en MS. En este cultivo, la relación Ca/Mg en solución ocasionalmente produjo efecto en la concentración de Ca en MS y en la exportación de Ca y Mg

    Evaluation of serological tests for Trichinella infections in pigs

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    The Dutch slaughter pig population is practically free of Trichinella spiralis. However, at slaughter every pig is tested for presence of larvae using the digestion method for export certification . A new 2006 EU directive concerning meat inspection for Trichinella spp. offers new opportunities to monitor Trichinella at herd level instead. Also serological methods are allowed when approved by the Commumty Reference Laboratory (CRL). To evaluate the usefulness of serological tests for momtoring a virtually free population for Trichinella, Bayesian methodology was used to estimate the diagnostic test parameters sensitivity and specificity, in the absence of a Gold Standard test

    Nuclear rupture at sites of high curvature compromises retention of DNA repair factors.

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    The nucleus is physically linked to the cytoskeleton, adhesions, and extracellular matrix-all of which sustain forces, but their relationships to DNA damage are obscure. We show that nuclear rupture with cytoplasmic mislocalization of multiple DNA repair factors correlates with high nuclear curvature imposed by an external probe or by cell attachment to either aligned collagen fibers or stiff matrix. Mislocalization is greatly enhanced by lamin A depletion, requires hours for nuclear reentry, and correlates with an increase in pan-nucleoplasmic foci of the DNA damage marker γH2AX. Excess DNA damage is rescued in ruptured nuclei by cooverexpression of multiple DNA repair factors as well as by soft matrix or inhibition of actomyosin tension. Increased contractility has the opposite effect, and stiff tumors with low lamin A indeed exhibit increased nuclear curvature, more frequent nuclear rupture, and excess DNA damage. Additional stresses likely play a role, but the data suggest high curvature promotes nuclear rupture, which compromises retention of DNA repair factors and favors sustained damage

    Post-treatment follow-up study of abdominal cystic echinococcosis in Tibetan communities of northwest Sichuan Province, China

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    Background: Human cystic echinococcosis (CE), caused by the larval stage of Echinococcus granulosus, with the liver as the most frequently affected organ, is known to be highly endemic in Tibetan communities of northwest Sichuan Province. Antiparasitic treatment with albendazole remains the primary choice for the great majority of patients in this resource-poor remote area, though surgery is the most common approach for CE therapy that has the potential to remove cysts and lead to complete cure. The current prospective study aimed to assess the effectiveness of community based use of cyclic albendazole treatment in Tibetan CE cases, and concurrently monitor the changes of serum specific antibody levels during treatment. Methodology/Principal Findings: Ultrasonography was applied for diagnosis and follow-up of CE cases after cyclic albendazole treatment in Tibetan communities of Sichuan Province during 2006 to 2008, and serum specific IgG antibody levels against Echinococcus granulosus recombinant antigen B in ELISA was concurrently monitored in these cases. A total of 196 CE cases were identified by ultrasound, of which 37 (18.9%) showed evidence of spontaneous healing/involution of hepatic cyst(s) with CE4 or CE5 presentations. Of 49 enrolled CE cases for treatment follow-up, 32.7% (16) were considered to be cured based on B-ultrasound after 6 months to 30 months regular albendazole treatment, 49.0% (24) were improved, 14.3% (7) remained unchanged, and 4.1% (2) became aggravated. In general, patients with CE2 type cysts (daughter cysts present) needed a longer treatment course for cure (26.4 months), compared to cases with CE1 (univesicular cysts) (20.4 months) or CE3 type (detached cyst membrane or partial degeneration of daughter cysts) (9 months). In addition, the curative duration was longer in patients with large (.10 cm) cysts (22.3 months), compared to cases with medium (5– 10 cm) cysts (17.3 months) or patients with small (,5 cm) cysts (6 months). At diagnosis, seven (53.8%) of 13 cases with CE1 type cysts without any previous intervention showed negative specific IgG antibody response to E. granulosus recombinant antigen B (rAgB). However, following 3 months to 18 months albendazole therapy, six of these 7 initially seronegative CE1 cases sero-converted to be specific IgG antibody positive, and concurrently ultrasound scan showed that cysts changed to CE3a from CE1 type in all the six CE cases. Two major profiles of serum specific IgG antibody dynamics during albendazole treatment were apparent in CE cases: (i) presenting as initial elevation followed by subsequent decline, or (ii) a persistent decline. Despite a decline, however, specific antibody levels remained positive in most improved or cured CE cases. Conclusions: This was the first attempt to follow up community-screened cystic echinococcosis patients after albendazole therapy using ultrasonography and serology in an endemic Tibetan region. Cyclic albendazole treatment proved to be effective in the great majority of CE cases in this resource-poor area, but periodic abdominal ultrasound examination was necessary to guide appropriate treatment. Oral albendazole for over 18 months was more likely to result in CE cure. Poor drug compliance resulted in less good outcomes. Serology with recombinant antigen B could provide additional limited information about the effectiveness of albendazole in CE cases. Post-treatment positive specific IgG antibody seroconversion, in initially seronegative, CE1 patients was considered a good indication for positive therapeutic efficacy of albendazole
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