The cone of Betti tables over a rational normal curve

We describe the cone of Betti tables of Cohen-Macaulay modules over the homogeneous coordinate ring of a rational normal curve.Comment: 9 pages; v2: corrected typos, added references, Section 5, and details to proof

The Flash Crash: An Examination of Shareholder Wealth and Market Quality

We investigate stock returns, market quality, and options market activity around the flash crash of May 6, 2010. Abnormal returns are negative on the day of and the day after the flash crash for stocks that had trades that executed during the crash subsequently cancelled by either Nasdaq or NYSE Arca. Consistent with studies that suggest that other sources of liquidity withdrew from the markets during the flash crash, we find that the fraction of trades executed by the NYSE increases during this volatile period. Market quality deteriorates following the flash crash as bid-ask spreads increase and quote depths decrease. Evidence from the options markets indicates that investor uncertainty increased around the time of the crash and remained elevated for several days

Acceleration of DDSCAT Computation by Parallelization on a Supercomputer

The DDSCAT software is enabled for use of MPI or OpenMP to distribute calculation of different particle orientations amongst multiple processors on a high performance system. Run times for these simulations have been tested to take hours or days however and simulating varying orientations is not always necessary. If a simulation with only one particle orientation is submitted, DDSCAT could still potentially parallelize the simulation by wavelength calculations but it is unknown if this is the case. In this paper, we will be (i) quantifying the reduction in computation time that MPI provides relative to an equivalent MPI disabled simulation and (ii) suggesting a method to additionally improve computation time when executing in a high performance computing environment

Environmental impact assessment and environmental management plan - a case study of magnesite and dunite mine, South India

The Chalk Hills region of Salem, Tamil Nadu, South India, has been the producer of magnesite of both calcination and refractory grades, for more than a century. Due to the vein type nature of the mineralisation, mining of this white carbonate of magnesium involves employment of men and deployment of heavy earth moving machines. The host rock, dunite, is also being mined as it is a commercially valuable by-product. The mining activity, comprising drilling, blasting (both primary and secondary), loading of waste, transport of over burden and crushing of ore is having considerable impacts on the environment. Dust generation, noise levels and ground vibration were monitored as part of the Environmental Impact Assessment (EIA). Control measures recommended on the basis of findings of EIA are being practiced. Review studies were conducted to gauge the healing effects following the implementation of the Environmental Management Plan (EMP). Implementation of the EMP points towards the sustenance of a clean, safe and congenial working environment in the mine and its precincts

Effects of lengthscales and attractions on the collapse of hydrophobic polymers in water

We present results from extensive molecular dynamics simulations of collapse transitions of hydrophobic polymers in explicit water focused on understanding effects of lengthscale of the hydrophobic surface and of attractive interactions on folding. Hydrophobic polymers display parabolic, protein-like, temperature-dependent free energy of unfolding. Folded states of small attractive polymers are marginally stable at 300 K, and can be unfolded by heating or cooling. Increasing the lengthscale or decreasing the polymer-water attractions stabilizes folded states significantly, the former dominated by the hydration contribution. That hydration contribution can be described by the surface tension model, $\Delta G=\gamma (T)\Delta A$, where the surface tension, $\gamma$, is lengthscale dependent and decreases monotonically with temperature. The resulting variation of the hydration entropy with polymer lengthscale is consistent with theoretical predictions of Huang and Chandler (Proc. Natl. Acad. Sci.,97, 8324-8327, 2000) that explain the blurring of entropy convergence observed in protein folding thermodynamics. Analysis of water structure shows that the polymer-water hydrophobic interface is soft and weakly dewetted, and is characterized by enhanced interfacial density fluctuations. Formation of this interface, which induces polymer folding, is strongly opposed by enthalpy and favored by entropy, similar to the vapor-liquid interface.Comment: 24 pages, 5 figure

Tailoring of Energy Band Gap inGraphene-like System by Fluorination

Fluorinated grapheme has a two-dimensional layer structure with a wide band gap. In the present study, Fluoro Graphene (FG) is obtained from Graphene Oxide (GO) through a deoxyfluorination reaction with the aid of Diethylaminosulphurtrifluoride (DAST). The FT-IR exhibited a peak at 1216 cm-1 and the shoulder at 1312 cm-1 were ascribed to the stretching vibration of covalent C–F bonds and C–F2 bonds, respectively. Surface morphology revealed a leafy structure in GO and a rocky structure in FG. The EDS analysis confirmed the fluorination of the graphitic structure. The TEM analysis confirmed the formation of a mixed structure of graphene and carbon dots. The results of structural, morphological and electrical properties of both graphene oxide and fluorographene show the possibility of using these samples as electronic/electrochemical devices in future

A Trust-Based Approach for Management of Dynamic QoS Violations in Cloud Federation Environments

Cloud Federation is an emerging technology where Cloud Service Providers (CSPs) offering specialized services to customers collaborate in order to reap the real benefits of Cloud Computing. When a CSP in the Cloud Federation runs out of resources, it can get the required resources from other partners in the federation. Normally, there will be QoS agreements between the partners in the federation for the resource sharing. In this paper, we propose a trust based mechanism for the management of dynamic QoS violations, when one CSP requests resources from another CSP in the federation. In this work, we have implemented the partner selection process, when one CSP does not have enough resources, using the Analytic Hierarchy Process (AHP) and the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) methods, and also considering the trust values of various CSPs in the federation. We have also implemented the Single Sign-On (SSO) authentication in the cloud federation using the Fully Hashed Menezes-Qu-Vanstone (FHMQV) protocol and AES-256 algorithm. The proposed trust-based approach is used to dynamically manage the QoS violations among the partners in the federation. We have implemented the proposed approach using the CloudSim toolkit, and the analysis of the results are also given