2,958 research outputs found

    Deformations of special geometry: in search of the topological string

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    The topological string captures certain superstring amplitudes which are also encoded in the underlying string effective action. However, unlike the topological string free energy, the effective action that comprises higher-order derivative couplings is not defined in terms of duality covariant variables. This puzzle is resolved in the context of real special geometry by introducing the so-called Hesse potential, which is defined in terms of duality covariant variables and is related by a Legendre transformation to the function that encodes the effective action. It is demonstrated that the Hesse potential contains a unique subsector that possesses all the characteristic properties of a topological string free energy. Genus g3g\leq3 contributions are constructed explicitly for a general class of effective actions associated with a special-K\"ahler target space and are shown to satisfy the holomorphic anomaly equation of perturbative type-II topological string theory. This identification of a topological string free energy from an effective action is primarily based on conceptual arguments and does not involve any of its more specific properties. It is fully consistent with known results. A general theorem is presented that captures some characteristic features of the equivalence, which demonstrates at the same time that non-holomorphic deformations of special geometry can be dealt with consistently.Comment: 44 pages, LaTex; v2, v3: minor text improvement

    Anomalous in-plane magneto-optical anisotropy of self-assembled quantum dots

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    We report on a complex nontrivial behavior of the optical anisotropy of quantum dots that is induced by a magnetic field in the plane of the sample. We find that the optical axis either rotates in the opposite direction to that of the magnetic field or remains fixed to a given crystalline direction. A theoretical analysis based on the exciton pseudospin Hamiltonian unambiguously demonstrates that these effects are induced by isotropic and anisotropic contributions to the heavy-hole Zeeman term, respectively. The latter is shown to be compensated by a built-in uniaxial anisotropy in a magnetic field B_c = 0.4 T, resulting in an optical response typical for symmetric quantum dots.Comment: 5 pages, 3 figure

    Thematic Analysis to Assess Indian Consumers Purchase Intention for Organic Apparel

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    Consumer behavior is dynamic, and there is a beauty in trying to understand consumer’s intention for a product category like organic apparel, especially when it is a unique phenomenon that is scantly explored in an emerging economy like India. This paper is an attempt at understanding the factors that influence Indian consumer’s intention to purchase organic apparel. A purposive sampling procedure was adopted in selecting participants. A focus group discussion was conducted to capture data for the thematic analysis. Theoretical thematic analysis was conducted by relying on the theory of planned behavior model. Inductive thematic analysis gave way for other dimensions like product knowledge and involvement, environmental knowledge, and skepticism that evolved out of the themes. Product knowledge and involvement, subjective norms, perceived behavioral control, and attitude had an influence on the intention. Environmental knowledge and skepticism indicated a chance to negate the relationship. The textile manufacturers, who are innovating with sustainable fabrics, can look at the dimensions that consumers seek for while making a choice of organic apparel. Domestic and international organic apparel manufacturers can capitalize on the behavioral dimensions of the factors that influence consumer’s intention for organic apparel, thereby facilitating identifying the prospect

    Preparation and Optimization of Pyrophosphate Bath for Copper Electroplating of Microwave Components

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    The principles of copper deposition from pyrophosphate electrolytes have been explained. Based on these principles, a method  of preparation of plating bath from basic constituents has been described. It was found that copper pyrophosphate is precipitated from solutions of copper sulphatc and potassium pyrophosphate at a pH of 5.0. For maximum efficiency, copper pyrophosphate has to be disolved in potassium pyrophosphate in a weight ratio of 1 : 4 or a total P2o7,: Cu ratio of 7.5 : 1. By using optimum values of anode : cathode area,2.5, pH, 5.0, temperature, 55°C and a cathode curfent density of 0.8 A/dm2, bright, adherent copper electroplates were deposited on electroless copper plated Al2o3, substrates employed in microwave components

    Spontaneous breaking of time reversal symmetry in strongly interacting two dimensional electron layers in silicon and germanium

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    We report experimental evidence of a remarkable spontaneous time reversal symmetry breaking in two dimensional electron systems formed by atomically confined doping of phosphorus (P) atoms inside bulk crystalline silicon (Si) and germanium (Ge). Weak localization corrections to the conductivity and the universal conductance fluctuations were both found to decrease rapidly with decreasing doping in the Si:P and Ge:P δ\delta-layers, suggesting an effect driven by Coulomb interactions. In-plane magnetotransport measurements indicate the presence of intrinsic local spin fluctuations at low doping, providing a microscopic mechanism for spontaneous lifting of the time reversal symmetry. Our experiments suggest the emergence of a new many-body quantum state when two dimensional electrons are confined to narrow half-filled impurity bands

    Testing general relativity via direct measurement of black hole kicks

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    Asymmetric emission of gravitational waves during a compact binary coalescence results in the loss of linear momentum and a corresponding `kick' or recoil on the binary's center of mass. This leads to a direction-dependent Doppler shift of the ringdown gravitational waveform. We quantify the measurability of the kick imparted to the remnant black hole in a binary black hole merger. Future ground- and space-based gravitational wave detectors will measure this effect to within 2%\sim 2\% to 30%\sim 30\% for a subset of their expected observed sources. Certain binary configurations in the LISA band may allow a sub-percent-level measurement of this effect. This direct measurement of black hole kicks can also facilitate a novel test of general relativity based on linear momentum balance. We formulate this kick consistency test via measurement of a null variable that quantifies the difference between the inferred kick (using numerical relativity) and that observed via the Doppler-shifted ringdown signal. This null variable can be constrained (at 90% confidence) to 10%\sim 10\% to 30%30\% with Cosmic Explorer and to 3%\sim 3\% to 12%12\% with LISA.Comment: 7 pages, 3 figure

    Climate Change Vulnerability in Agriculture Sector: Indexing and Mapping of Four Southern Indian States

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    Agriculture is the sector most vulnerable to climate change due to its high dependence on climate and weather conditions. Climate change is a main challenge for agriculture, food security and rural livelihoods for millions of people in India. Among India’s population of more than one billion people, about 68% are directly or indirectly involved in the agricultural sector. This sector is particularly vulnerable to present-day climate variability. In this paper an attempt is made to map and analyze the vulnerability to climate change in different districts of four south Indian states: Andhra Pradesh, Karnataka, Tamil Nadu and Kerala. We have taken five sources of vulnerability indicators: socio-demographic, climatic, agricultural, occupational and common property resources vulnerabilities to compute the composite vulnerability index. The composite vulnerability index suggests that, Adilabad, Chamarajanagar, Thiruvarur and Kasaragod are the most vulnerable districts of Andhra Pradesh, Karnataka, Tamil Nadu and Kerala respectively, whereas Hyderabad, Belgaum, Thoothukkudi, Kottayam are the least vulnerable districts

    HyBIS: Windows Guest Protection through Advanced Memory Introspection

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    Effectively protecting the Windows OS is a challenging task, since most implementation details are not publicly known. Windows has always been the main target of malwares that have exploited numerous bugs and vulnerabilities. Recent trusted boot and additional integrity checks have rendered the Windows OS less vulnerable to kernel-level rootkits. Nevertheless, guest Windows Virtual Machines are becoming an increasingly interesting attack target. In this work we introduce and analyze a novel Hypervisor-Based Introspection System (HyBIS) we developed for protecting Windows OSes from malware and rootkits. The HyBIS architecture is motivated and detailed, while targeted experimental results show its effectiveness. Comparison with related work highlights main HyBIS advantages such as: effective semantic introspection, support for 64-bit architectures and for latest Windows (8.x and 10), advanced malware disabling capabilities. We believe the research effort reported here will pave the way to further advances in the security of Windows OSes
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