4,790 research outputs found

    Sterile neutrinos, dark matter, and resonant effects in ultra high energy regimes

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    Interest in light dark matter candidates has recently increased in the literature; some of these works consider the role of additional neutrinos, either active or sterile. Furthermore, extragalactic neutrinos have been detected with energies higher than have ever been reported before. This opens a new window of opportunities to the study of neutrino properties that were unreachable up to now. We investigate how an interaction potential between neutrinos and dark matter might induce a resonant enhancement in the oscillation probability, an effect that may be tested with future neutrino data.Comment: 11 pages, 2 figures, to be published in PL

    Evaluation of wood basic density as an indirect measurement of the volume of wood raw material

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    The manufacturing process of wood agglomerate integrates distinct unit that transforms wood raw material into wood agglomerate. The yield of wood agglomerate produced is influenced by the density and the quality of the initial raw material. This work has compared two distinct methodologies aimed at defining the yield of the process through an indirect measurement at the precursor material. Samples (logs of differentiated sizes) were collected immediately at the industry entrance and several parameters were measured. The logs basic density and the moisture content was annotated, through analysis of the corresponding dry and wet mass. Log bark percentage has estimated also at the level of dry and wet basis. These parameters were used to determine the wood volume from different provenance and species in the beginning of the industrial process. The results indicated that wasn’t a great difference between the two different methods to determine the wood basic density and the wood volume in m3. Principal components analysis was used to investigate the differences between different provenances and different species for the wood basic density, and we conclude there is a great variability in wood basic density for the hardwood species than the observed for the softwood and there isn’t a great variability between different provenances. We study too the difference off wood moisture that could be occurring before the evaluation of wood basic density

    Functionalized Mesoporous Solids Based On Magadiite And [al]-magadiite.

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    Novel hybrid mesoporous and functionalized materials with controllable surface area and pore dimensions with functional basic sites (-NH2) were synthesized from magadiite and [Al]-magadiite as layered silicate precursors. The variable pore structure and properties of these materials were investigated in these solids by using different CTA(+)/Na(+) (CTA(+) = cetyltrimethylammonium cation) molar ratios in the pre-modification step with aminopropyltriethoxysilane (APTS) and tetraethoxysilane (TEOS). Characterizations were carried out by different techniques to probe the effects of the amounts of interlayer surfactant in the synthesis of the pillared and/or grafted materials. The crystalline structures of magadiite and [Al]-magadiite layers were maintained as evidenced by FT-IR and SAED and contain pillars and aminopropyl groups in the interlayer space. The hybrid solids were compared to the pillared forms (H. M. Moura, F. A. Bonk and H. O. Pastore, Eur. J. Mineral., 2012, 24, 903) and to the aminopropyl-grafted forms and presented the properties of both solids with the CO2 adsorption capability improved considerably.4310471-8

    A Routing/Assignment Problem in Garden Maintenance Services

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    We address a routing/assignment problem posed by Neoturf, which is a Portuguese company working in the area of project, building and garden’s main- tenance. The aim is to define a procedure for scheduling and routing efficiently its clients of garden maintenance services. The company has two teams available throughout the year to handle all the maintenance jobs. Each team consists of two or three employees with a fully-equipped vehicle capable of carrying out every kind of maintenance service. At the beginning of each year, the number and frequency of maintenance interventions to conduct during the year, for each client, are agreed. Time windows are established so that visits to the client should occur only within these periods. There are clients that are supposed to be always served by the same team, but other clients can be served indifferently by any of the two teams. Since clients are geographically spread over a wide region, the total distance traveled while visiting clients is a factor that weighs heavily on the company costs. Neoturf is con- cerned with reducing these costs, while satisfying agreements with its clients. We give a mixed integer linear programming formulation for the problem, discuss lim- itations on the size of instances that can be solved to guarantee optimality, present a modification of the Clarke and Wright heuristic for the vehicle routing with time windows, and report preliminary computational results obtained with Neoturf data.info:eu-repo/semantics/publishedVersio

    Energy metabolism in human pluripotent stem cells and their differentiated counterparts

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    Background: Human pluripotent stem cells have the ability to generate all cell types present in the adult organism, therefore harboring great potential for the in vitro study of differentiation and for the development of cell-based therapies. Nonetheless their use may prove challenging as incomplete differentiation of these cells might lead to tumoregenicity. Interestingly, many cancer types have been reported to display metabolic modifications with features that might be similar to stem cells. Understanding the metabolic properties of human pluripotent stem cells when compared to their differentiated counterparts can thus be of crucial importance. Furthermore recent data has stressed distinct features of different human pluripotent cells lines, namely when comparing embryo-derived human embryonic stem cells (hESCs) and induced pluripotent stem cells (IPSCs) reprogrammed from somatic cells. Methodology/Principal Findings: We compared the energy metabolism of hESCs, IPSCs, and their somatic counterparts. Focusing on mitochondria, we tracked organelle localization and morphology. Furthermore we performed gene expression analysis of several pathways related to the glucose metabolism, including glycolysis, the pentose phosphate pathway and the tricarboxylic acid (TCA) cycle. In addition we determined oxygen consumption rates (OCR) using a metabolic extracellular flux analyzer, as well as total intracellular ATP levels by high performance liquid chromatography (HPLC). Finally we explored the expression of key proteins involved in the regulation of glucose metabolism. Conclusions/Findings: Our results demonstrate that, although the metabolic signature of IPSCs is not identical to that of hESCs, nonetheless they cluster with hESCs rather than with their somatic counterparts. ATP levels, lactate production and OCR revealed that human pluripotent cells rely mostly on glycolysis to meet their energy demands. Furthermore, our work points to some of the strategies which human pluripotent stem cells may use to maintain high glycolytic rates, such as high levels of hexokinase II and inactive pyruvate dehydrogenase (PDH). © 2011 Varum et al

    TaXEm: a tool for aiding the evaluation of domain topic.

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    The notorious advances in textual information storage need fast and effcient tools to organize, retrieve and browse this information and tools for knowledge extraction. A very interesting way to organize specific domain information is the topic taxonomy building. Moreover a great challenge in this research area is the result evaluation and validation. This evaluation can be carried out through objective measures or through a subjective analysis, which is based on the domain specialist judgment. The measures CQM and SQM [1] are used to evaluate a generated taxonomy against a reference taxonomy. A reference taxonomy is constructed by human and consolidated through its community use along the years. The CQM is used to evaluate the generated taxonomy relatively to the selected descriptors for each taxonomy node; on the other hand, the SQM is used to evaluate the taxonomy structure. As these objective measures do not encompass the specialist knowledge, the specialist evaluation is very important. However the human evaluation is expensive, because this task involves readiness, time and dedication from the specialists. In this way, the TaXEm tool claims to reduce the subjective evaluation costs. The TaXEm (Taxonomia em XML da Embrapa) tool offers subsidies for carrying out a taxonomy (semi)automatic evaluation, which allows the user to implement some automatic evaluation before going on a subjective evaluation.Propor 2010. Demonstration
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