Given a setV ofn points ink-dimensional space, and anLq-metric (Minkowski metric), the all-nearest-neighbors problem is defined as follows: for each pointp inV, find all those points inV–{p} that are closest top under the distance metricLq. We give anO(n logn) algorithm for the all-nearest-neighbors problem, for fixed dimensionk and fixed metricLq. Since there is an (n logn) lower bound, in the algebraic decision-tree model of computation, on the time complexity of any algorithm that solves the all-nearest-neighbors problem (fork=1), the running time of our algorithm is optimal up to a constant factor.This research was supported by a fellowship from the Shell Foundation. The author is currently at AT&T Bell Laboratories, Murray Hill, New Jersey, USA. 相似文献
Cellulose dissolution in the viscose process has been facilitated through derivatization by carbon disulphide (CS2) at xanthation stage by converting alkali cellulose (AC) to cellulose xanthate (CX). CX formation has been always accompanied with sulphur based byproducts formation as dictated by the mechanism published in earlier study (Gondhalekar et al. (Cellulose 26 3 1595–1604, 2019)). The sulphur byproducts formed during viscose synthesis are sodium sulphide (Na2S), sodium trithiocarbonate (Na2CS3: TTC) and other minor sulphur compounds. These byproducts continue to form during ripening process as dictated by time and temperature coupled with concentration of free caustic and CS2 present in the system. These byproducts get converted into sodium sulphate (Na2SO4), hydrogen sulphide (H2S), CS2 and other sulphurous compounds during spinning. Overall, uncontrolled ripening without parametric optimization adversely impacts raw material (RM) consumption and creates sustainability challenges. Overall optimization based on viscose process fundamental insights presented in this study will effectively help in achieving operational excellence by reducing rate of undesired reactions to improve RM specific consumption and will compliment overall sustainability efforts in viscose industry.
The present paper demonstrates a single-step and straightforward synthesis of parvaquone through intermediacy of cyclohexyl radical generated from novel combination of cyclohexylhydrazine and o-iodoxybenzoic acid and subsequently trapped by 2-hydroxy-1,4-naphthoquinone. Formation of cyclohexyl free radical using this new combination was reaffirmed by cyclohexylation of readily available 2-amino-1,4-naphthoquinone. 相似文献
Preparation of 4‐amino‐2‐aryl quinazolines by reduction of N‐(2‐cyanoaryl) amidoximes via amidines using SnCl2 in ethanol. J. Heterocyclic Chem., (2011). 相似文献
The diffraction of an optical vortex through an iris diaphragm which is a close approximation to a circular aperture has been investigated. The results are compared with those obtained from the diffraction of a Gaussian beam through the same aperture. In our findings the diffraction of an optical vortex and a Gaussian beam produce ball bearing sort of structure of darkness and brightness. The singularity of the vortex beam is found to be consistent even after the diffraction through the aperture. The presence of singularity at the centre of diffraction pattern of an optical vortex has been confirmed by interferometry. There is a good agreement between the experimental and numerical results. We propose that these results may find various applications in optical trapping experiments. 相似文献
The dissociation constants of some derivatives of 5-amino isophthalic acid have been measured by Calvin Bjerrum pH titration
method in DMF-water and DMSO-water (60: 40 v/v) systems at 308.15 K. It is observed that dissociation constant depends on
the solvent and substituents group present in the compound. 相似文献
Skin cancer is the most common form of cancer diagnosed in the United States. Exposure to solar ultraviolet (UV) radiations is believed to be the primary cause for skin cancer. Excessive UV radiation can lead to genetic mutations and damage in the skin's cellular DNA that in turn can lead to skin cancer. Lately, chemoprevention by administering naturally occurring non-toxic dietary compounds has proven to be a potential strategy to prevent the occurrence of tumors. Attention has been drawn toward several natural dietary agents such as resveratrol, one of the major components found in grapes, red wines, berries and peanuts, proanthocyanidins from grape seeds, (-)-epigallocatechin-3-gallate from green tea, etc. However, the effect these dietary agents have on the immune system and the immunological mechanisms involved therein are still being explored. In this review, we shall focus on the role of key chemopreventive agents on various immune cells and discuss their potential as antitumor agents with an immunological perspective. 相似文献