2,961 research outputs found
Deformations of special geometry: in search of the topological string
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 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
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
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
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
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 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
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 to 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 to with Cosmic Explorer and to to
with LISA.Comment: 7 pages, 3 figure
Climate Change Vulnerability in Agriculture Sector: Indexing and Mapping of Four Southern Indian States
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
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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