550 research outputs found

    Charmed Hadrons from Fragmentation and B Decays

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    The fragmentation functions of D0D^0, D±D^{\pm}, Ds±D_s^{\pm}, D∗oD^{*o}, D∗±D^{*\pm} and Λc±\Lambda_c^{\pm} at s\sqrt{s}≃\simeq10.6 GeV are measured with a data set of 102.7 fb−1^{-1}. Fragmentation model parametrizations (Peterson, Kartvelishvili, Collins-Spiller, Lund, and Bowler models) are compared to the data. The data at high xx≃\simeq1 indicate a contribution of non-perturbative QCD processes.Comment: presented at CHARM2006, International Workshop on Tau-Charm Physics, Beijing, June 5-7, 200

    On-line analytical processing in distributed data warehouses

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    The concepts of 'data warehousing' and 'on-line analytical processing' have seen a growing interest in the research and commercial product community. Today, the trend moves away from complex centralized data warehouses to distributed data marts integrated in a common conceptual schema. However, as the first part of this paper demonstrates, there are many problems and little solutions for large distributed decision support systems in worldwide operating corporations. After showing the benefits and problems of the distributed approach, this paper outlines possibilities for achieving performance in distributed online analytical processing. Finally, the architectural framework of the prototypical distributed OLAP system CUBESTAR is outlined

    Data Mining in a Multidimensional Environment

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    Data Mining and Data Warehousing are two hot topics in the database research area. Until recently, conventional data mining algorithms were primarily developed for a relational environment. But a data warehouse database is based on a multidimensional model. In our paper we apply this basis for a seamless integration of data mining in the multidimensional model for the example of discovering association rules. Furthermore, we propose this method as a userguided technique because of the clear structure both of model and data. We present both the theoretical basis and efficient algorithms for data mining in the multidimensional data model. Our approach uses directly the requirements of dimensions, classifications and sparsity of the cube. Additionally we give heuristics for optimizing the search for rules

    Visual search without central vision – no single pseudofovea location is best

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    We typically fixate targets such that they are projected onto the fovea for best spatial resolution. Macular degeneration patients often develop fixation strategies such that targets are projected to an intact eccentric part of the retina, called pseudofovea. A longstanding debate concerns which pseudofovea-location is optimal for non-foveal vision. We examined how pseudofovea position and eccentricity affect performance in visual search, when vision is restricted to an off-foveal retinal region by a gaze-contingent display that dynamically blurs the stimulus except within a small viewing window (forced field location). Trained normally sighted participants were more accurate when forced field location was congruent with the required scan path direction; this contradicts the view that a single pseudofovea location is generally best. Rather, performance depends on the congruence between pseudofovea location and scan path direction

    Transistor Effects and in situ STM of Redox Molecules at Room Temperature.

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    Benchmarking Big Data Technologies for Energy Procurement Efficiency

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    The electrical power industry is undergoing radical change due to the push for renewable energy that makes energy supply less predictable. Smart meters along with analytics software can grant insights into customer-specific consumption and thereby enable a better match between the demand and supply side for an electric utility. However, the vast amount of allocatable smart metering data and complexity of analytics pose challenges to database system. We address the implementation of an analytics ap-proach to optimize customer portfolios, eventually preventing excess energy procurement. Using real-world and simulated data, we test the suitability of big data approaches as well as traditional relational database technology. Furthermore, we present solutions based on big data platforms and demonstrate their cost effectiveness and performance. Our findings suggest economic feasibility of big data solutions for large utilities. Small and medium-sized utilities are advised to invest in more cost-effective solutions such as cluster-based systems

    Query optimization by using derivability in a data warehouse environment

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    Materialized summary tables and cached query results are frequently used for the optimization of aggregate queries in a data warehouse. Query rewriting techniques are incorporated into database systems to use those materialized views and thus avoid the access of the possibly huge raw data. A rewriting is only possible if the query is derivable from these views. Several approaches can be found in the literature to check the derivability and find query rewritings. The specific application scenario of a data warehouse with its multidimensional perspective allows the consideration of much more semantic information, e.g. structural dependencies within the dimension hierarchies and different characteristics of measures. The motivation of this article is to use this information to present conditions for derivability in a large number of relevant cases which go beyond previous approaches

    Hypothermia and postconditioning after cardiopulmonary resuscitation reduce cardiac dysfunction by modulating inflammation, apoptosis and remodeling

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    Background: Mild therapeutic hypothermia following cardiac arrest is neuroprotective, but its effect on myocardial dysfunction that is a critical issue following resuscitation is not clear. This study sought to examine whether hypothermia and the combination of hypothermia and pharmacological postconditioning are cardioprotective in a model of cardiopulmonary resuscitation following acute myocardial ischemia. Methodology/Principal Findings: Thirty pigs (28–34 kg) were subjected to cardiac arrest following left anterior descending coronary artery ischemia. After 7 minutes of ventricular fibrillation and 2 minutes of basic life support, advanced cardiac life support was started according to the current AHA guidelines. After successful return of spontaneous circulation (n = 21), coronary perfusion was reestablished after 60 minutes of occlusion, and animals were randomized to either normothermia at 38°C, hypothermia at 33°C or hypothermia at 33°C combined with sevoflurane (each group n = 7) for 24 hours. The effects on cardiac damage especially on inflammation, apoptosis, and remodeling were studied using cellular and molecular approaches. Five animals were sham operated. Animals treated with hypothermia had lower troponin T levels (p<0.01), reduced infarct size (34±7 versus 57±12%; p<0.05) and improved left ventricular function compared to normothermia (p<0.05). Hypothermia was associated with a reduction in: (i) immune cell infiltration, (ii) apoptosis, (iii) IL-1beta and IL-6 mRNA up-regulation, and (iv) IL-1beta protein expression (p<0.05). Moreover, decreased matrix metalloproteinase-9 activity was detected in the ischemic myocardium after treatment with mild hypothermia. Sevoflurane conferred additional protective effects although statistic significance was not reached. Conclusions/Significance: Hypothermia reduced myocardial damage and dysfunction after cardiopulmonary resuscitation possible via a reduced rate of apoptosis and pro-inflammatory cytokine expression

    Sonographic diagnosis and Endo-SPONGE assisted vacuum therapy of anastomotic leakage following posterior pelvic exenteration for ovarian cancer without using a protective stoma

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    Anastomotic leakage is a very significant complication after posterior pelvic exenteration and a major cause of postoperative morbidity and mortality. We present a patient who underwent an optimal debulking surgery for an advanced stage ovarian cancer (FIGO IIIC). On postoperative day 12, transvaginal ultrasound revealed an anastomotic dehiscence following an unsuspicious computer tomography scan the day before. The patient was successfully managed by transanal vacuum therapy without re-laparotomy within a period of 4 weeks after diagnosis. We conclude that high-resolution transvaginal ultrasound is a crucial method in the management of complications after surgery and even allow diagnosing leakages of colorectal anastomosis. In selected cases characterized by a small leak size and a local peritonitis confined to the pelvis a transanal vacuum therapy may avoid both surgical re-intervention and creating a secondary diverting stoma

    Surface induced orientation and vertically layered morphology in thin films of poly(3-hexylthiophene) crystallized from the melt

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    The presence of interfaces and geometrical confinement can have a strong influence on the structure and morphology of thin films of semicrystalline polymers. Using surface-sensitive grazing incidence wide angle X-ray scattering and atomic force microscopy to investigate the vertical structure of thin films of poly(3-hexylthiophene) crystallized from the melt, we show that highly oriented crystallites are induced at the air/polymer interface and not as sometimes assumed at the interface to the substrate. These crystallites are oriented with their crystallographic a-axis perpendicular to the plane of the film. While the corresponding orientation dominates in thinner films, for sufficiently thick films (>60 nm) a layer containing unoriented crystals is present below the surface layer. Due to the anisotropic charge transport properties, the observed effects are expected to be of special relevance for potential applications of semiconductor polymers in the field of organic photovoltaics for which vertical transport in thicker films plays an important role
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