796 research outputs found

    Large deviations of the maximal eigenvalue of random matrices

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    We present detailed computations of the 'at least finite' terms (three dominant orders) of the free energy in a one-cut matrix model with a hard edge a, in beta-ensembles, with any polynomial potential. beta is a positive number, so not restricted to the standard values beta = 1 (hermitian matrices), beta = 1/2 (symmetric matrices), beta = 2 (quaternionic self-dual matrices). This model allows to study the statistic of the maximum eigenvalue of random matrices. We compute the large deviation function to the left of the expected maximum. We specialize our results to the gaussian beta-ensembles and check them numerically. Our method is based on general results and procedures already developed in the literature to solve the Pastur equations (also called "loop equations"). It allows to compute the left tail of the analog of Tracy-Widom laws for any beta, including the constant term.Comment: 62 pages, 4 figures, pdflatex ; v2 bibliography corrected ; v3 typos corrected and preprint added ; v4 few more numbers adde

    Price-based control of ancillary services for power balancing

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    A reliable and an efficient power system is a necessity for any industrialized society. Governments have to enforce regulations to guarantee that such a power system, in spite of many competing stakeholders, participants, companies, and regulating agencies can be operational. This paper analyzes the present arrangements and the future requirements to be posed on incentives and regulation for ancillary services (AS) for power balancing. The paper proposes companies to assess their own needs for AS. A two-sided market for AS is being described to replace the existing arrangements for secondary control. The proposed solution guarantees a reliable and efficient operation of power systems in a market environment with responsive, reliable, and accountable but also competing prosumers, a large penetration of less-predictable renewables and continent-spanning transmission networks

    Congestion management in the deregulated electricity market: An assessment of locational pricing, redispatch and regulation

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    We analyze the fundamental differences between locational pricing and redispatch-based congestion management, followed by an assessment of their effects on grid operation and market efficiency. It is indicated that although optimal nodal pricing and congestion redispatch can provide equal results in terms of power injections, they are not equivalent in terms of short-run social welfare. Moreover, a modeling framework is presented to decouple and analyze the effects of transmission system operator/regulator and prosumer behavior on energy market efficiency in a transparent fashion. All results are illustrated on the basis of case studies for the IEEE 39-bus New England test network

    Application of support vector machines on the basis of the first Hungarian bankruptcy model

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    In our study we rely on a data mining procedure known as support vector machine (SVM) on the database of the first Hungarian bankruptcy model. The models constructed are then contrasted with the results of earlier bankruptcy models with the use of classification accuracy and the area under the ROC curve. In using the SVM technique, in addition to conventional kernel functions, we also examine the possibilities of applying the ANOVA kernel function and take a detailed look at data preparation tasks recommended in using the SVM method (handling of outliers). The results of the models assembled suggest that a significant improvement of classification accuracy can be achieved on the database of the first Hungarian bankruptcy model when using the SVM method as opposed to neural networks

    Reliability and efficiency at global level in power systems

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    In EU project E-Price it is proposed to attribute reliability to the Transmission System Operator (TSO) and the drive for efficiency to the Balance Responsible Parties (BRP). Two main ideas are proposed. The first idea is to make BRPs themselves responsible for estimating their uncertainty in real time and hedge their imbalance risks, yielding the proposal to introduce dual-sided markets for ancillary services. The second idea is to reduce the conservatism in exploiting the inter-area transmission capacity (ATC), while still guaranteeing sufficient degrees of reliability. This paper explains, elucidates and concludes, based on qualitative arguments and supported by quantitative simulations and calculations, that both proposals are beneficial to improve the stated compromise between reliability and economy

    Optical data of meteoritic nano-diamonds from far-ultraviolet to far-infrared wavelengths

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    We have used different spectroscopic techniques to obtain a consistent quantitative absorption spectrum of a sample of meteoritic nano-diamonds in the wavelength range from the vacuum ultraviolet (0.12 μ\mum) to the far infrared (100 μ\mum). The nano-diamonds have been isolated by a chemical treatment from the Allende meteorite (Braatz et al.2000). Electron energy loss spectroscopy (EELS) extends the optical measurements to higher energies and allows the derivation of the optical constants (n & k) by Kramers-Kronig analysis. The results can be used to restrain observations and to improve current models of the environment where the nano-diamonds are expected to have formed. We also show that the amount of nano-diamond which can be present in space is higher than previously estimated by Lewis et al. (1989).Comment: 11 pages, 7 figure

    Phenology and temperature‐dependent development of Ceutorhynchus assimilis, a potential biological control agent for Lepidium draba

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    Lepidium draba (Brassicaceae) is a major concern for agriculture and biodiversity in the western United States. As current control methods do not provide long-term, sustainable solutions, research has been conducted to find biological control agents. Ceutorhynchus assimilis is one of the currently investigated candidates. Known as oligophagous in the literature, a specialist clade of this root-galling weevil exists in southern Europe. This raised the question of its ability to survive in colder climates in the target range. We investigated the phenology of C. assimilis in the field in southern France (specialist clade) and Romania (generalist clade) and measured various temperature-dependent parameters in the laboratory. In both ranges, weevils were univoltine. Oviposition in autumn started later in France compared to Romania, while mature larvae exited galls (to pupate in the soil) earlier the following year. On average, 25% and 32% of galls from France and Romania were completely below the soil surface, respectively, and this appeared to depend on soil substrate. Weevils transported from France to Romania were able to develop, but at a much lower rate than Romanian weevils. Mortality of overwintering larvae of both clades increased with decreasing temperature and exposure time. At −5°C, lethal times Lt50 and Lt95 were 15 and 42 days for the specialist clade and 26 and 72 days for the generalist clade. A higher proportion of third instar larvae compared to first and second instar larvae survived. Pupation time at different temperatures did not differ between weevils from France or Romania. A climate match model (comparing winter temperatures) indicated that the specialist clade of C. assimilis from France has the potential to establish in some parts of the target range (e.g. Washington, Oregon, California). However, temperature extremes and winters without snow cover will likely limit its establishment unless rapid adaptive evolution takes place

    OPTIMIZATION AND CHARACTERIZATION OF DOXORUBICIN LOADED SOLID LIPID NANOSUSPENSION FOR NOSE TO BRAIN DELIVERY USING DESIGN EXPERT SOFTWARE

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    Objective: The goal of the current study was to investigate the possible use of solid lipid nanosuspension (SLNs) as a drug delivery method to boost doxorubicin (DOX) brain-targeting performance after intranasal (i. n.) administration.  Methods: 33 factorial design was applied for optimization by using lipid concentration, surfactant concentration, and High-speed homogenizer (HSH) stirring time as dependent variables, and their effect was observed on particles size, Polydispersity index (PDI), and entrapment efficiency.  Results: With the composition of Compritol® 888 ATO (4.6 % w/v), tween 80 (1.9 % w/v), and HSH stirring time, the optimized formula DOX-SLNs prepared (10 min). Particle size, PDI, zeta potential, entrapment efficiency, percent in vitro release were found to be 167.47±6.09 nm, 0.23±0.02, 24.1 mV, 75.3±2.79, and 89.35±3.27 percent in 24 h, respectively, for optimized formulation (V-O). No major changes in particle size, zeta potential, and entrapping efficiency were found in the stability studies at 4±2 °C (refrigerator) and 25±2 °C/60±5% RH up to 3 mo.  Conclusion: Following the non-invasive nose-to-brain drug delivery, which is a promising therapeutic strategy, the positive findings confirmed the current optimized DOX-loaded SLNs formulation

    EphA2-receptor deficiency exacerbates myocardial infarction and reduces survival in hyperglycemic mice

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    Background We have previously shown that EphrinA1/EphA expression profile changes in response to myocardial infarction (MI), exogenous EphrinA1-Fc administration following MI positively influences wound healing, and that deletion of the EphA2 Receptor (EphA2-R) exacerbates injury and remodeling. To determine whether or not ephrinA1-Fc would be of therapeutic value in the hyperglycemic infarcted heart, it is critical to evaluate how ephrinA1/EphA signaling changes in the hyperglycemic myocardium in response to MI. Methods Streptozotocin (STZ)-induced hyperglycemia in wild type (WT) and EphA2-receptor mutant (EphA2-R-M) mice was initiated by an intraperitoneal injection of STZ (150 mg/kg) 10 days before surgery. MI was induced by permanent ligation of the left anterior descending coronary artery and analyses were performed at 4 days post-MI. ANOVAs with Student-Newman Keuls multiple comparison post-hoc analysis illustrated which groups were significantly different, with significance of at least p < 0.05. Results Both WT and EphA2-R-M mice responded adversely to STZ, but only hyperglycemic EphA2-R-M mice had lower ejection fraction (EF) and fractional shortening (FS). At 4 days post-MI, we observed greater post-MI mortality in EphA2-R-M mice compared with WT and this was greater still in the EphA2-R-M hyperglycemic mice. Although infarct size was greater in hyperglycemic WT mice vs normoglycemic mice, there was no difference between hyperglycemic EphA2-R-M mice and normoglycemic EphA2-R-M mice. The hypertrophic response that normally occurs in viable myocardium remote to the infarct was noticeably absent in epicardial cardiomyocytes and cardiac dysfunction worsened in hyperglycemic EphA2-R-M hearts post-MI. The characteristic interstitial fibrotic response in the compensating myocardium remote to the infarct also did not occur in hyperglycemic EphA2-R-M mouse hearts to the same extent as that observed in the hyperglycemic WT mouse hearts. Differences in neutrophil and pan-leukocyte infiltration and serum cytokines implicate EphA2-R in modulation of injury and the differences in ephrinA1 and EphA6-R expression in governing this are discussed. Conclusions We conclude that EphA2-mutant mice are more prone to hyperglycemia-induced increased injury, decreased survival, and worsened LV remodeling due to impaired wound healing
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