On Semi - Symmetric Projective Connection

In this paper we consider a new connection called Semi-Symmetric Projective Connection. The covariant differentiation with respect to this connection is defined and the commutation formulae for directional differentiation, Berwald covariant differentiation and semi-symmetric projective covariant differentiation have been obtained. Relations between the curvature tensors and torsion tensors arising from Berwald connection  and semi-symmetric projective  connection have also been obtained. Bianchi identities have also been derived

Optimizing Nondecomposable Data Dependent Regularizers via Lagrangian Reparameterization offers Significant Performance and Efficiency Gains

Data dependent regularization is known to benefit a wide variety of problems in machine learning. Often, these regularizers cannot be easily decomposed into a sum over a finite number of terms, e.g., a sum over individual example-wise terms. The $F_\beta$ measure, Area under the ROC curve (AUCROC) and Precision at a fixed recall (P@R) are some prominent examples that are used in many applications. We find that for most medium to large sized datasets, scalability issues severely limit our ability in leveraging the benefits of such regularizers. Importantly, the key technical impediment despite some recent progress is that, such objectives remain difficult to optimize via backpropapagation procedures. While an efficient general-purpose strategy for this problem still remains elusive, in this paper, we show that for many data-dependent nondecomposable regularizers that are relevant in applications, sizable gains in efficiency are possible with minimal code-level changes; in other words, no specialized tools or numerical schemes are needed. Our procedure involves a reparameterization followed by a partial dualization -- this leads to a formulation that has provably cheap projection operators. We present a detailed analysis of runtime and convergence properties of our algorithm. On the experimental side, we show that a direct use of our scheme significantly improves the state of the art IOU measures reported for MSCOCO Stuff segmentation dataset

EFFECT OF ANNEALING ON STRUCTURES AND EFFECTIVE THERMAL CONDUCTIVITY OF Se 90 In 10 CHALCOGENIDE GLASS

The annealing phenomena have been observed on the pellets of Se 90 In 10 chalcogenide glass by annealing at 50 o C and 100 o C for 2h. The structure and effective thermal conductivity of as prepared and annealed samples of Se 90 In 10 chalcogenide have been investigated by XRD and transient plane source (TPS) method, respectively. A considerable change has been found in both structures and effective thermal conductivity for annealing at 50 o C (2h). However, by annealing at 100 o C for 2h the glassy Se 90 In 10 transforms into crystalline Se 90 In 10 and its effective thermal conductivity drastically decreases. Therefore, the change of the structure and of the effective thermal conductivity of Se 90 In 10 chalcogenide glassy material evidence specific structural relaxation phenomena

Quantum Nature of the Big Bang: Improved dynamics

An improved Hamiltonian constraint operator is introduced in loop quantum cosmology. Quantum dynamics of the spatially flat, isotropic model with a massless scalar field is then studied in detail using analytical and numerical methods. The scalar field continues to serve as `emergent time', the big bang is again replaced by a quantum bounce, and quantum evolution remains deterministic across the deep Planck regime. However, while with the Hamiltonian constraint used so far in loop quantum cosmology the quantum bounce can occur even at low matter densities, with the new Hamiltonian constraint it occurs only at a Planck-scale density. Thus, the new quantum dynamics retains the attractive features of current evolutions in loop quantum cosmology but, at the same time, cures their main weakness.Comment: Typos corrected. Revised version to appear in Physical Review

Comparative genomic analysis reveals habitat-specific genes and regulatory hubs within the genus Novosphingobium

© The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in mSystems 2 (2017): e00020-17, doi:10.1128/mSystems.00020-17.Species belonging to the genus Novosphingobium are found in many different habitats and have been identified as metabolically versatile. Through comparative genomic analysis, we identified habitat-specific genes and regulatory hubs that could determine habitat selection for Novosphingobium spp. Genomes from 27 Novosphingobium strains isolated from diverse habitats such as rhizosphere soil, plant surfaces, heavily contaminated soils, and marine and freshwater environments were analyzed. Genome size and coding potential were widely variable, differing significantly between habitats. Phylogenetic relationships between strains were less likely to describe functional genotype similarity than the habitat from which they were isolated. In this study, strains (19 out of 27) with a recorded habitat of isolation, and at least 3 representative strains per habitat, comprised four ecological groups—rhizosphere, contaminated soil, marine, and freshwater. Sulfur acquisition and metabolism were the only core genomic traits to differ significantly in proportion between these ecological groups; for example, alkane sulfonate (ssuABCD) assimilation was found exclusively in all of the rhizospheric isolates. When we examined osmolytic regulation in Novosphingobium spp. through ectoine biosynthesis, which was assumed to be marine habitat specific, we found that it was also present in isolates from contaminated soil, suggesting its relevance beyond the marine system. Novosphingobium strains were also found to harbor a wide variety of mono- and dioxygenases, responsible for the metabolism of several aromatic compounds, suggesting their potential to act as degraders of a variety of xenobiotic compounds. Protein-protein interaction analysis revealed β-barrel outer membrane proteins as habitat-specific hubs in each of the four habitats—freshwater (Saro_1868), marine water (PP1Y_AT17644), rhizosphere (PMI02_00367), and soil (V474_17210). These outer membrane proteins could play a key role in habitat demarcation and extend our understanding of the metabolic versatility of the Novosphingobium species.This work was supported by grants from the Department of Biotechnology (DBT), R.K., S.H., K.P., A.B., and U.S. gratefully acknowledge the National Bureau of Agriculturally Important Microorganisms (NBAIM), Science and Engineering Research Board (SERB), N-PDF (PDF/2015/000062), (PDF/2015, 000319), University Grant Commission (UGC) for the Dr. D. S. Kothari Postdoctoral Fellowship and UGC for providing fellowships, respectively

Quantum geometry and the Schwarzschild singularity

In homogeneous cosmologies, quantum geometry effects lead to a resolution of the classical singularity without having to invoke special boundary conditions at the singularity or introduce ad-hoc elements such as unphysical matter. The same effects are shown to lead to a resolution of the Schwarzschild singularity. The resulting quantum extension of space-time is likely to have significant implications to the black hole evaporation process. Similarities and differences with the situation in quantum geometrodynamics are pointed out.Comment: 31 pages, 1 figur

Luminomagnetic bifunctionality of Mn2+-bonded graphene oxide/reduced graphene oxide two dimensional nanosheets

Herein, we report the luminomagnetic bifunctional properties of two-dimensional (2D) Mn2+ bonded graphene oxide (GO)/reduced graphene oxide (RGO) nanosheets synthesized using a facile route of oxidation followed by a solvothermal reduction method. Photoluminescence (PL) studies (excited by different wavelengths) revealed that the resonant energy transfer between Mn2+ and sp(3)/sp(2) clusters of GO/RGO is responsible for the enhancement of emissions. Moreover, pH-sensitive PL behaviors have also been investigated in detail. The ferromagnetic behavior is believed to arise due to defects in Mn2+ bonded GO composites. Thus, present reduction method provides a direct route to tune and enhance the optical properties of GO and RGO nanosheets bonded with Mn2+ ions, which creates an opportunity for various technological applications

ATXN3 controls DNA replication and transcription by regulating chromatin structure

The deubiquitinating enzyme Ataxin-3 (ATXN3) contains a polyglutamine (PolyQ) region, the expansion of which causes spinocerebellar ataxia type-3 (SCA3). ATXN3 has multiple functions, such as regulating transcription or controlling genomic stability after DNA damage. Here we report the role of ATXN3 in chromatin organization during unperturbed conditions, in a catalytic-independent manner. The lack of ATXN3 leads to abnormalities in nuclear and nucleolar morphology, alters DNA replication timing and increases transcription. Additionally, indicators of more open chromatin, such as increased mobility of histone H1, changes in epigenetic marks and higher sensitivity to micrococcal nuclease digestion were detected in the absence of ATXN3. Interestingly, the effects observed in cells lacking ATXN3 are epistatic to the inhibition or lack of the histone deacetylase 3 (HDAC3), an interaction partner of ATXN3. The absence of ATXN3 decreases the recruitment of endogenous HDAC3 to the chromatin, as well as the HDAC3 nuclear/cytoplasm ratio after HDAC3 overexpression, suggesting that ATXN3 controls the subcellular localization of HDAC3. Importantly, the overexpression of a PolyQ-expanded version of ATXN3 behaves as a null mutant, altering DNA replication parameters, epigenetic marks and the subcellular distribution of HDAC3, giving new insights into the molecular basis of the disease.</p