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11.
Weak gravitational lensing is responsible for the shearing and magnification of the images of high-redshift sources due to the presence of intervening matter. The distortions are due to fluctuations in the gravitational potential, and are directly related to the distribution of matter and to the geometry and dynamics of the Universe. As a consequence, weak gravitational lensing offers unique possibilities for probing the Dark Matter and Dark Energy in the Universe. In this review, we summarise the theoretical and observational state of the subject, focussing on the statistical aspects of weak lensing, and consider the prospects for weak lensing surveys in the future. 相似文献
12.
Kunal Kumar Jha Sanjay Dutta Saibal Sar Subhabrata Sen Parthapratim Munshi 《Tetrahedron》2018,74(51):7326-7334
Presence of cyclobutane rings in bioactive natural products makes them a popular synthetic target. Most common strategy for synthesizing cyclobutanes is [2+2] cycloaddition, which is usually facilitated by using ultraviolet radiation and catalysts. Herein we report the design and synthesis of densely functionalized cyclobutanes by alleviating these drawbacks and using sunlight. Further, we identified the putative mechanism of the transformation based on kinetic, fluorescence and crystallographic studies and evaluated biological activities of the products against MCF7 cell lines. The rational design of the olefinic substrates was based on their UV–vis spectra. The generic aspect of the reaction was elucidated by the syntheses of diverse analogs of cyclobutanes. Further, crystal structures and UV–vis spectra of the olefinic partners assisted us in rationalizing the stereoselectivity of the heterodimers. We believe this energy-efficient mild approach will provide a substantial contribution to the existing repertoire of strategies to regio- and stereoselectively access cyclobutanes. 相似文献
13.
Ginseng is a widely used medicinal product that grows mainly in Korea, China and America. American ginseng is classified as an endangered species, and so the import and export of this type of ginseng is illegal in certain countries. Due to this restriction it is becoming increasingly important to be able to distinguish between different types of ginseng. FT-Raman spectroscopy has the ability to discriminate between ginseng specimens according to the country of origin and the effects of processing on the ginseng material. The ginsenoside content of ginseng differs in both conformation and concentration depending on the source of the ginseng, which means that ginseng grown in different countries should express unique spectral features. The presence or absence of these features, therefore, could indicate the geographical origin of the sample. Several spectral features were identified for a range of ginsengs, such as a peak at 980 cm(-1) that was only found in Chinese ginseng, and the different wavenumber positions of characteristic ginseng bands near 1600 cm(-1). This indicates that Raman spectroscopy can be used to pinpoint the origin of an unknown ginseng sample and that it would provide a rapid nondestructive analytical technique for formally discriminating between restricted and permitted imports. 相似文献
14.
Vera Novak Mareile Haertle Peng Zhao Kun Hu Medha Munshi Peter Novak Amir Abduljalil David Alsop 《Magnetic resonance imaging》2009
Background
White matter hyperintensities (WMHs) on MRI have been associated with age, cardiovascular risk factors and falls in the elderly. This study evaluated the relationship between WMHs and dynamics of postural control in older adults without history of falls.Methods
We studied 76 community-living subjects without history of falls (age 64.5±7.3 years). Brain and WMH volume calculations and clinical rating were done on fluid-attenuation inversion recovery (FLAIR) and MP-RAGE MR images on 3 T. Balance was assessed from the center of pressure displacement using the force platform during 3 min of quiet standing using traditional and dynamic measures (using stabilogram-diffusion analysis). Gait speed was measured from 12-min walk.Results
Age-adjusted periventricular and focal WMHs were associated with changes in certain dynamic balance measures, including reduced range of postural sway in anteroposterior direction (fronto-temporal WMHs, P=.045; parieto-occipital WMHs, P=.009) and more irregular long-term mediolateral fluctuations (P=.046). Normal walking speed was not affected by WMHs.Conclusions
Periventricular and focal WMHs affect long-term dynamics of postural control, which requires engagement of feedback mechanisms, and may contribute to mobility decline in the elderly. 相似文献15.
Amit Aran Soumika Munshi Vinod K. Beri Arun K. Gupta 《Optics and Lasers in Engineering》2009,47(6):636-643
This paper reports a morphological phase-only correlation technique based on bit-map representation for recognition of color as well as grey images in a hybrid digital-optical correlation architecture. The color image is decomposed into its R, G and B components, and each component is further decomposed into eight disjoint elementary images depending upon the bit-map representation of the color value at each pixel. Bit-map representation of the pixel values of an image reduces the required computational time. A set of twenty-four disjoint wavelet-modified binary phase-only filters (WBPOFs) are generated from these bit-map decomposed images. The target image is similarly decomposed into eight disjoint images each of R, G and B and their digital Fourier transforms multiplied with the corresponding WBPOFs. The product functions thus obtained are added up to form a single resultant product function, whose optical Fourier transformation gives the correlation peaks for the presence of R, G and B components in the image. The single product function overcomes the necessity of obtaining the final optical Fourier transformation of the R, G and B components separately. The novelty of this approach lies in the fact that the WBPOFs synthesized by this procedure are thus able to identify both colored as well as gray images and can tolerate salt-and-pepper noise to a considerable extent. 相似文献
16.
H. R. H. Ali H. G. M. Edwards J. Kendrick T. Munshi I. J. Scowen 《Journal of Raman spectroscopy : JRS》2007,38(7):903-908
The Raman spectrum of budesonide is reported for the first time, and molecular assignments are proposed on the basis of ab initio BLYP DFT calculations with a 6‐31 G* basis set and vibrational wavenumbers predicted on a quasi‐harmonic approximation. Comparison with previously published infrared data has explained several spectral features, and the relative band intensities in the CO and CC stretching regions are interpreted. The results from this study provide data that can be used for the preparative process monitoring of budesonide, an important steroidal pharmaceutical in various dosage forms, and its interaction with excipients and other components. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
17.
Sayan Sarkar Dr. Piyali Sarkar Sandip Munshi Prof. Pradyut Ghosh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(25):7307-7314
Selectivity of aryl iodo over ethynyl iodo toward the Suzuki cross coupling reaction is explored by utilizing a palladium complex of amino-ether heteroditopic macrobicycle. Subsequently, unreacted ethynyl iodide undergoes homocoupling reaction in the same catalytic atmosphere, thereby representing a cascade dual C−C coupling reaction. Furthermore, this approach is extended for novel one-pot synthesis of unsymmetrical 1,3-diynes. 相似文献
18.
P. Munshi P. Jayakumar P. Satyamurthy T. K. Thiyagarajan N. S. Dixit N. Venkatramani 《Experiments in fluids》1998,24(5-6):424-430
A steady-state vertical mercury-nitrogen flow system has been investigated using three tomographic algorithms. Void-fraction
profiles have been reconstructed by the data collected by a 60 mCi gamma-ray source and a single Na(Tl) detector. The results
indicate excellent agreement (within ±1%) between the least-squares-solution and the chord-segment-inversion algorithms. The
data-collection time for each data-ray was varied so that in each case 3000 counts could be collected to reduce the detrimental
effect of Poisson statistics in the reconstructed profiles. Eleven sets of data have been collected for nitrogen flow-rates
between 0.00123 and 0.00884 kg/s. The mercury flow-rates were between 17.6 and 34.1 kg/s. The resulting cross-sectional average
void varied between 0.10 and 0.38.
Received: 13 March 1997/Accepted: 12 September 1997 相似文献
19.
We consider the problem of achieving coordinated actions in a real-time distributed system. In particular, we consider how closely (in terms of real time) processors can be guaranteed to perform a particular action, in a system where message transmission is guaranteed, but there is some uncertainty in message transmission time. We present an algorithm to achieve optimal precision in arbitrary networks. In networks where clocks run at the rate of real time, the optimal precision achievable in a network is exactly how tightly clocks can be guaranteed to be synchronized. 相似文献
20.
Summary A systematic scheme for the identification of the common anions: sulphate, sulphite, nitrate, nitrite, fluoride, chloride, bromide, iodide, ferricyanide, ferrocyanide, thiocyanate, phosphate, sulphide, thiosulphate and borate in a mixture by the ring oven technique has been described.
Zusammenfassung Ein systematischer Analysengang zum Nachweis folgender Anionen mit Hilfe des Ringofens wurde beschrieben: Sulfat, Sulfit, Nitrat, Nitrit, Fluorid, Chlorid, Bromid, Jodid, Cyanoferrat(III), Cyanoferrat (II), Rhodanid, Phosphat, Sulfid, Thiosulfat und Borat.
Résumé On a décrit un plan d'identification systématique des anions usuels dans leurs mélanges: sulfate, sulfite, nitrate, nitrite, fluorure, chlorure, bromure, iodure, ferricyanure, ferrocyanure, thiocyanate, phosphate, sulfure, thiosulfate et borate, au moyen de la technique du four annulaire.相似文献