993 resultados para 204-1247


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We associate a sheaf model to a class of Hilbert modules satisfying a natural finiteness condition. It is obtained as the dual to a linear system of Hermitian vector spaces (in the sense of Grothendieck). A refined notion of curvature is derived from this construction leading to a new unitary invariant for the Hilbert module. A division problem with bounds, originating in Douady's privilege, is related to this framework. A series of concrete computations illustrate the abstract concepts of the paper.

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The reaction of the benzoylhydrazone of 2-hydroxybenzaldehyde (H2L) with MoO2(acac)(2)] proceeds smoothly in refluxing ethanol to afford an orange complex MoO2L(C2H5OH)] (1). The substrate binding capacity of 1 has been demonstrated by the formation and isolation of two mononuclear MoO2L(Q)] {where Q = imidazole (2a) and 1-methylimidazole (2b)} and one dinuclear (MoO2L)(2)(Q)] {Q = 4,4'-bipyridine (3)} mixed-ligand oxomolybdenum complex. All the complexes have been characterized by elemental analysis, magnetic and spectroscopic (IR, UV-Vis and NMR) measurements. The molecular structures of all the oxomolybdenum(VI) complexes (1, 2a, 2b and 3) have been determined by X-ray crystallography. In each complex, the dianionic planar ligand is coordinated to the metal centre via one enolate oxygen, one phenolate oxygen and an azomethine nitrogen atom. The complexes have been screened for their antibacterial activity against Escherichia coli, Bacillus and Pseudomonas aeruginosa. The minimum inhibitory concentration of these complexes and their antibacterial activity indicates that compounds 2a and 2b are potential lead molecules for drug designing. (C) 2012 Elsevier Ltd. All rights reserved.

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We consider a dense, ad hoc wireless network, confined to a small region. The wireless network is operated as a single cell, i.e., only one successful transmission is supported at a time. Data packets are sent between source-destination pairs by multihop relaying. We assume that nodes self-organize into a multihop network such that all hops are of length d meters, where d is a design parameter. There is a contention-based multiaccess scheme, and it is assumed that every node always has data to send, either originated from it or a transit packet (saturation assumption). In this scenario, we seek to maximize a measure of the transport capacity of the network (measured in bit-meters per second) over power controls (in a fading environment) and over the hop distance d, subject to an average power constraint. We first motivate that for a dense collection of nodes confined to a small region, single cell operation is efficient for single user decoding transceivers. Then, operating the dense ad hoc wireless network (described above) as a single cell, we study the hop length and power control that maximizes the transport capacity for a given network power constraint. More specifically, for a fading channel and for a fixed transmission time strategy (akin to the IEEE 802.11 TXOP), we find that there exists an intrinsic aggregate bit rate (Theta(opt) bits per second, depending on the contention mechanism and the channel fading characteristics) carried by the network, when operating at the optimal hop length and power control. The optimal transport capacity is of the form d(opt)((P) over bar (t)) x Theta(opt) with d(opt) scaling as (P) over bar (t) (1/eta), where (P) over bar (t) is the available time average transmit power and eta is the path loss exponent. Under certain conditions on the fading distribution, we then provide a simple characterization of the optimal operating point. Simulation results are provided comparing the performance of the optimal strategy derived here with some simple strategies for operating the network.

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We report the design and development of a self-contained multi-band receiver (MBR) system, intended for use with a single large aperture to facilitate sensitive and high time-resolution observations simultaneously in 10 discrete frequency bands sampling a wide spectral span (100-1500 MHz) in a nearly log-periodic fashion. The development of this system was primarily motivated by need for tomographic studies of pulsar polar emission regions. Although the system design is optimized for the primary goal, it is also suited for several other interesting astronomical investigations. The system consists of a dual-polarization multi-band feed (with discrete responses corresponding to the 10 bands pre-selected as relatively radio frequency interference free), a common wide-band radio frequency front-end, and independent back-end receiver chains for the 10 individual sub-bands. The raw voltage time sequences corresponding to 16 MHz bandwidth each for the two linear polarization channels and the 10 bands are recorded at the Nyquist rate simultaneously. We present the preliminary results from the tests and pulsar observations carried out with the Robert C. Byrd Green Bank Telescope using this receiver. The system performance implied by these results and possible improvements are also briefly discussed.

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Examination of type material and new collections from Goa, southern Maharashtra and northern Karnataka, leads to the conclusion that Gegeneophis nadkarnii Bhatta & Prashanth, 2004 is a subjective junior synonym of Gegeneophis danieli Giri, Wilkinson & Gower, 2003. The purported differences between these species are very minor and attributable to normal individual variation, except for some features of the dentition that are peculiar to the exceptionally abnormal paratype of G. nadkarnii. This taxonomic revision extends the known geographic range of G. danieli and suggests it could be transferred from Data Deficient to Least Concern status in the IUCN Red List.

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In a networked society, governing advocacy groups and networks through decentralized systems of policy implementation has been the interest of governance network literature. This paper addresses the topic of governing networks in the context of Indian agrarian societies by taking the case example of a welfare scheme for the Indian rural poor. We explore context-specific regulatory dynamics through the situated agent based architectural framework. The effects of various regulatory strategies that can be adopted by governing node are tested under various action arenas through experimental design. Results show the impact of regulatory strategies on the resource dependencies and asymmetries in the network relationships. This indicates that the optimal feasible regulatory strategy in networked society is institutionally rational and is context dependent. Further, we show that situated MAS architecture is a natural fit for institutional understanding of the dynamics (Ostrom et al. in Rules, games, and common-pool resources, 1994).

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Using Genetic Algorithm, a global optimization method inspired by nature's evolutionary process, we have improved the quantitative refocused constant-time INEPT experiment (Q-INEPT-CT) of Makela et al. (JMR 204 (2010) 124-130) with various optimization constraints. The improved `average polarization transfer' and `min-max difference' of new delay sets effectively reduces the experimental time by a factor of two (compared with Q-INEPT-CT, Makela et al.) without compromising on accuracy. We also discuss a quantitative spectral editing technique based on average polarization transfer. (C) 2013 Elsevier Inc. All rights reserved.

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Electrical Impedance Tomography (EIT) is a computerized medical imaging technique which reconstructs the electrical impedance images of a domain under test from the boundary voltage-current data measured by an EIT electronic instrumentation using an image reconstruction algorithm. Being a computed tomography technique, EIT injects a constant current to the patient's body through the surface electrodes surrounding the domain to be imaged (Omega) and tries to calculate the spatial distribution of electrical conductivity or resistivity of the closed conducting domain using the potentials developed at the domain boundary (partial derivative Omega). Practical phantoms are essentially required to study, test and calibrate a medical EIT system for certifying the system before applying it on patients for diagnostic imaging. Therefore, the EIT phantoms are essentially required to generate boundary data for studying and assessing the instrumentation and inverse solvers a in EIT. For proper assessment of an inverse solver of a 2D EIT system, a perfect 2D practical phantom is required. As the practical phantoms are the assemblies of the objects with 3D geometries, the developing of a practical 2D-phantom is a great challenge and therefore, the boundary data generated from the practical phantoms with 3D geometry are found inappropriate for assessing a 2D inverse solver. Furthermore, the boundary data errors contributed by the instrumentation are also difficult to separate from the errors developed by the 3D phantoms. Hence, the errorless boundary data are found essential to assess the inverse solver in 2D EIT. In this direction, a MatLAB-based Virtual Phantom for 2D EIT (MatVP2DEIT) is developed to generate accurate boundary data for assessing the 2D-EIT inverse solvers and the image reconstruction accuracy. MatVP2DEIT is a MatLAB-based computer program which simulates a phantom in computer and generates the boundary potential data as the outputs by using the combinations of different phantom parameters as the inputs to the program. Phantom diameter, inhomogeneity geometry (shape, size and position), number of inhomogeneities, applied current magnitude, background resistivity, inhomogeneity resistivity all are set as the phantom variables which are provided as the input parameters to the MatVP2DEIT for simulating different phantom configurations. A constant current injection is simulated at the phantom boundary with different current injection protocols and boundary potential data are calculated. Boundary data sets are generated with different phantom configurations obtained with the different combinations of the phantom variables and the resistivity images are reconstructed using EIDORS. Boundary data of the virtual phantoms, containing inhomogeneities with complex geometries, are also generated for different current injection patterns using MatVP2DEIT and the resistivity imaging is studied. The effect of regularization method on the image reconstruction is also studied with the data generated by MatVP2DEIT. Resistivity images are evaluated by studying the resistivity parameters and contrast parameters estimated from the elemental resistivity profiles of the reconstructed phantom domain. Results show that the MatVP2DEIT generates accurate boundary data for different types of single or multiple objects which are efficient and accurate enough to reconstruct the resistivity images in EIDORS. The spatial resolution studies show that, the resistivity imaging conducted with the boundary data generated by MatVP2DEIT with 2048 elements, can reconstruct two circular inhomogeneities placed with a minimum distance (boundary to boundary) of 2 mm. It is also observed that, in MatVP2DEIT with 2048 elements, the boundary data generated for a phantom with a circular inhomogeneity of a diameter less than 7% of that of the phantom domain can produce resistivity images in EIDORS with a 1968 element mesh. Results also show that the MatVP2DEIT accurately generates the boundary data for neighbouring, opposite reference and trigonometric current patterns which are very suitable for resistivity reconstruction studies. MatVP2DEIT generated data are also found suitable for studying the effect of the different regularization methods on reconstruction process. Comparing the reconstructed image with an original geometry made in MatVP2DEIT, it would be easier to study the resistivity imaging procedures as well as the inverse solver performance. Using the proposed MatVP2DEIT software with modified domains, the cross sectional anatomy of a number of body parts can be simulated in PC and the impedance image reconstruction of human anatomy can be studied.

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Investigations on the electrical switching, structural, optical and photoacoustic analysis have been undertaken on chalcogenide GeSe1.5S0.5 thin films of various thicknesses prepared by vacuum evaporation technique. The decrease of band gap energy with increase in film thickness has been explained using the `density of states model'. The structural units of the films are characterized using Raman spectroscopy and the deconvoluted Raman peaks obtained from Gaussian fit around 188 cm(-1), 204 cm(-1) and 214 cm(-1) favors Ge-chalcogen tetrahedral units forming corner and edge sharing tetrahedra. All the thin films samples have been exhibited memory-type electrical switching behavior. An enhancement in the threshold voltages of GeSe1.5S0.5 thin films have been observed with increase in film thickness. The thickness dependence of switching voltages provide an insight into the switching mechanism and it is explained by the Joule heating effect. (C) 2014 Elsevier B.V. All rights reserved.

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Mutations in the CINCINNATA (CIN) gene in Antirrhinum majus and its orthologs in Arabidopsis result in crinkly leaves as a result of excess growth towards the leaf margin. CIN homologs code for TCP (TEOSINTE-BRANCHED 1, CYCLOIDEA, PROLIFERATING CELL FACTOR 1 AND 2) transcription factors and are expressed in a broad zone in a growing leaf distal to the proliferation zone where they accelerate cell maturation. Although a few TCP targets are known, the functional basis of CIN-mediated leaf morphogenesis remains unclear. We compared the global transcription profiles of wild-type and the cin mutant of A. majus to identify the targets of CIN. We cloned and studied the direct targets using RNA in situ hybridization, DNA-protein interaction, chromatin immunoprecipitation and reporter gene analysis. Many of the genes involved in the auxin and cytokinin signaling pathways showed altered expression in the cin mutant. Further, we showed that CIN binds to genomic regions and directly promotes the transcription of a cytokinin receptor homolog HISTIDINE KINASE 4 (AmHK4) and an IAA3/SHY2 (INDOLE-3-ACETIC ACID INDUCIBLE 3/SHORT HYPOCOTYL 2) homolog in A. majus. Our results suggest that CIN limits excess cell proliferation and maintains the flatness of the leaf surface by directly modulating the hormone pathways involved in patterning cell proliferation and differentiation during leaf growth. 10.1111/(ISSN)1469-8137

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In this study, thin films of cobalt oxide (Co3O4) have been grown by the metal-organic chemical vapor deposition (MOCVD) technique on stainless steel substrate at two preferred temperatures (450 degrees C and 500 degrees C), using cobalt acetylacetonate dihydrate as precursor. Spherical as well as columnar microstructures of Co3O4 have been observed under controlled growth conditions. Further investigations reveal these films are phase-pure, well crystallized and carbon-free. High-resolution TEM analysis confirms that each columnar structure is a continuous stack of minute crystals. Comparative study between these Co3O4 films grown at 450 degrees C and 500 degrees C has been carried out for their application as negative electrodes in Li-ion batteries. Our method of electrode fabrication leads to a coating of active material directly on current collector without any use of external additives. A high specific capacity of 1168 micro Ah cm(-2) mu m(-1) has been measured reproducibly for the film deposited at 500 degrees C with columnar morphology. Further, high rate capability is observed when cycled at different current densities. The Co3O4 electrode with columnar structure has a specific capacity 38% higher than the electrode with spherical microstructure (grown at 450 degrees C). Impedance measurements on the Co3O4 electrode grown at 500 degrees C also carried out to study the kinetics of the electrode process. (C) 2014 Published by Elsevier B.V.

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Two dinuclear copper(II) complexes Li(H2O)(3)(CH3OH)](4)Cu2Br4]Cu-2(cpdp)(mu-O2CCH3)](4)(OH)(2) (1), Cu (H2O)(4)]Cu-2(cpdp)(mu-O2CC6H5)](2)Cl-2 center dot 5H(2)O (2), and a dinuclear zinc(II) complex Zn-2(cpdp)(mu-O2CCH3)] (3) have been synthesized using pyridine and benzoate functionality based new symmetrical dinucleating ligand, N, N'-Bis2-carboxybenzomethyl]-N, N'-Bis2-pyridylmethyl]-1,3-diaminopropan-2-ol (H(3)cpdp). Complexes 1, 2 and 3 have been synthesized by carrying out reaction of the ligand H3cpdp with stoichiometric amounts of Cu-2(O2CCH3)(4)(H2O)(2)], CuCl2 center dot 2H(2)O/C6H5COONa, and Zn(CH3COO)(2)center dot 2H(2)O, respectively, in methanol in the presence of NaOH at ambient temperature. Characterizations of the complexes have been done using various analytical techniques including single crystal X-ray structure determination. The X-ray crystal structure analyses reveal that the copper(II) ions in complexes 1 and 2 are in a distorted square pyramidal geometry with Cu-Cu separation of 3.455(8) angstrom and 3.492(1)angstrom, respectively. The DFT optimized structure of complex 3 indicates that two zinc(II) ions are in a distorted square pyramidal geometry with Zn-Zn separation of 3.492(8)angstrom. UV-Vis and mass spectrometric analyses of the complexes confirm their dimeric nature in solution. Furthermore, H-1 and C-13 NMR spectroscopic investigations authenticate the integrity of complex 3 in solution. Variable-temperature (2-300 K) magnetic susceptibility measurements show the presence of antiferromagnetic interactions between the copper centers, with J = -26.0 cm(-1) and -23.9 cm(-1) ((H) over cap = -2JS(1)S(2)) in complexes 1 and 2, respectively. In addition, glycosidase-like activity of the complexes has been investigated in aqueous solution at pH similar to 10.5 by UV-Vis spectrophotometric technique using p-nitrophenyl-alpha-D-glucopyranoside (4) and p-nitrophenyl-beta-D-glucopyranoside (5) as model substrates. (C) 2015 Elsevier B.V. All rights reserved.

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Background: DNA methylation and its perturbations are an established attribute to a wide spectrum of phenotypic variations and disease conditions. Indian traditional system practices personalized medicine through indigenous concept of distinctly descriptive physiological, psychological and anatomical features known as prakriti. Here we attempted to establish DNA methylation differences in these three prakriti phenotypes. Methods: Following structured and objective measurement of 3416 subjects, whole blood DNA of 147 healthy male individuals belonging to defined prakriti (Vata, Pitta and Kapha) between the age group of 20-30years were subjected to methylated DNA immunoprecipitation (MeDIP) and microarray analysis. After data analysis, prakriti specific signatures were validated through bisulfite DNA sequencing. Results: Differentially methylated regions in CpG islands and shores were significantly enriched in promoters/UTRs and gene body regions. Phenotypes characterized by higher metabolism (Pitta prakriti) in individuals showed distinct promoter (34) and gene body methylation (204), followed by Vata prakriti which correlates to motion showed DNA methylation in 52 promoters and 139 CpG islands and finally individuals with structural attributes (Kapha prakriti) with 23 and 19 promoters and CpG islands respectively. Bisulfite DNA sequencing of prakriti specific multiple CpG sites in promoters and 5'-UTR such as; LHX1 (Vata prakriti), SOX11 (Pitta prakriti) and CDH22 (Kapha prakriti) were validated. Kapha prakriti specific CDH22 5'-UTR CpG methylation was also found to be associated with higher body mass index (BMI). Conclusion: Differential DNA methylation signatures in three distinct prakriti phenotypes demonstrate the epigenetic basis of Indian traditional human classification which may have relevance to personalized medicine.