Observations of the post shock break-out emission of SN 2011dh with XMM-Newton

After the occurrence of the type cIIb SN 2011dh in the nearby spiral galaxy M 51 numerous observations were performed with different telescopes in various bands ranging from radio to gamma-rays. We analysed the XMM-Newton and Swift observations taken 3 to 30 days after the SN explosion to study the X-ray spectrum of SN 2011dh. We extracted spectra from the XMM-Newton observations, which took place ~7 and 11 days after the SN. In addition, we created integrated Swift/XRT spectra of 3 to 10 days and 11 to 30 days. The spectra are well fitted with a power-law spectrum absorbed with Galactic foreground absorption. In addition, we find a harder spectral component in the first XMM-Newton spectrum taken at t ~ 7 d. This component is also detected in the first Swift spectrum of t = 3 - 10 d. While the persistent power-law component can be explained as inverse Compton emission from radio synchrotron emitting electrons, the harder component is most likely bremsstrahlung emission from the shocked stellar wind. Therefore, the harder X-ray emission that fades away after t ~ 10 d can be interpreted as emission from the shocked circumstellar wind of SN 2011dh.Comment: Accepted for publication as a Research Note in Astronomy and Astrophysic

The study of dynamic singularities of seismic signals by the generalized Langevin equation

Analytically and quantitatively we reveal that the generalized Langevin equation (GLE), based on a memory function approach, in which memory functions and information measures of statistical memory play a fundamental role in determining the thin details of the stochastic behavior of seismic systems, naturally leads to a description of seismic phenomena in terms of strong and weak memory. Due to a discreteness of seismic signals we use a finite-discrete form of the GLE. Here we studied some cases of seismic activities of Earth ground motion in Turkey with consideration of the complexity, nonergodicity and fractality of seismic signals. © 2009 Elsevier B.V. All rights reserved

Jamming Model for the Extremal Optimization Heuristic

Extremal Optimization, a recently introduced meta-heuristic for hard optimization problems, is analyzed on a simple model of jamming. The model is motivated first by the problem of finding lowest energy configurations for a disordered spin system on a fixed-valence graph. The numerical results for the spin system exhibit the same phenomena found in all earlier studies of extremal optimization, and our analytical results for the model reproduce many of these features.Comment: 9 pages, RevTex4, 7 ps-figures included, as to appear in J. Phys. A, related papers available at http://www.physics.emory.edu/faculty/boettcher

Riemannian Sparse Coding for Positive Definite Matrices

International audienceInspired by the great success of sparse coding for vector valued data, our goal is to represent symmetric positive definite (SPD) data matrices as sparse linear combinations of atoms from a dictionary, where each atom itself is an SPD matrix. Since SPD matrices follow a non-Euclidean (in fact a Riemannian) geometry, existing sparse coding techniques for Euclidean data cannot be directly extended. Prior works have approached this problem by defining a sparse coding loss function using either extrinsic similarity measures (such as the log-Euclidean distance) or kernelized variants of statistical measures (such as the Stein divergence, Jeffrey's divergence, etc.). In contrast, we propose to use the intrinsic Riemannian distance on the manifold of SPD matrices. Our main contribution is a novel mathematical model for sparse coding of SPD matrices; we also present a computationally simple algorithm for optimizing our model. Experiments on several computer vision datasets showcase superior classification and retrieval performance compared with state-of-the-art approaches

Extremal Optimization for Graph Partitioning

Extremal optimization is a new general-purpose method for approximating solutions to hard optimization problems. We study the method in detail by way of the NP-hard graph partitioning problem. We discuss the scaling behavior of extremal optimization, focusing on the convergence of the average run as a function of runtime and system size. The method has a single free parameter, which we determine numerically and justify using a simple argument. Our numerical results demonstrate that on random graphs, extremal optimization maintains consistent accuracy for increasing system sizes, with an approximation error decreasing over runtime roughly as a power law t^(-0.4). On geometrically structured graphs, the scaling of results from the average run suggests that these are far from optimal, with large fluctuations between individual trials. But when only the best runs are considered, results consistent with theoretical arguments are recovered.Comment: 34 pages, RevTex4, 1 table and 20 ps-figures included, related papers available at http://www.physics.emory.edu/faculty/boettcher

JOURNAL OF AGRICULTURAL SCIENCES-TARIM BILIMLERI DERGISI

This study was carried out at the organic land of Ege University Faculty of Agriculture, Department of Horticulture during the spring and autumn seasons. Three organic fertilizers were tested under two growing systems to determine yield, quality, plant growth and soil fertility in Romaine lettuce (cv. Yedikule) and lettuce (cv. Arapsaci) production. Experiments were conducted with 6 groups composed of two growing systems [under Agryl cover (A+) or open field conditions without Agryl (A-)] and three fertilizers [Biofarm (B), Biofarm + Humic Acid (BHa) and Biofarm + Leonardite (BL)] in two years and growing seasons (2005-spring and 2006-autumn) with factorial design. In both years, total yield and average plant weight increased with the use of agryl cover while among the tested fertilizers, BHa and B applications gave the highest yields in the 1(st) and 2(nd) year, respectively. Agryl cover affected plant length among the measured quality characteristics. Mean nitrate content of organic lettuces was found quite low than the limits. Effects of agryl cover and fertilizers on leaf nutrient content were significant whereas fertilizer treatments increased soil microbial biomass-C and organic matter content in the first yield. It was concluded that these treatments could be recommended to use in organic lettuce production due to the positive effects of agryl cover on yield and organic fertilizers on yield, quality and soil fertility

PROCEEDINGS OF THE IIIRD BALKAN SYMPOSIUM ON VEGETABLE AND POTATOES

This study was conducted in order to elucidate the problems in organic greenhouse cucumber growing. Two dosages of farmyard manure (15 or 30 tons ha(-1)) were tested during autumn and spring seasons of 2003 and 2004. Fruit samples were analyzed for their quality parameters (color and total dry matter content of fruits and total soluble solids, EC and pH of fruit juice) at three weeks intervals during the harvest period. Generally, there were no significant differences with respect to fruit properties between manure dosages in both growing seasons. Higher yield was in the farmyard manure application of 15 ton ha(-1) (5.92 kg/m(2)) compared to the application of 30 ton ha(-1) (3.95 kg/m(2)) in autumn season, whereas higher total yield (17.84 kg/m(2)) was obtained from the plants grown by the application of 30 ton ha(-1) farmyard manure in spring, but the difference between treatments was not statistically significant