The Scattered Disk as the source of the Jupiter Family comets

The short period Jupiter family comets (JFCs) are thought to originate in the Kuiper Belt; specifically, a dynamical subclass of the Kuiper Belt known as the `scattered disk' is argued to be the dominant source of JFCs. However, the best estimates from observational surveys indicate that this source may fall short by more than two orders of magnitude the estimates obtained from theoretical models of the dynamical evolution of Kuiper belt objects into JFCs. We re-examine the scattered disk as a source of the JFCs and make a rigorous estimate of the discrepancy. We find that the uncertainties in the dynamical models combined with a change in the size distribution function of the scattered disk at faint magnitudes (small sizes) beyond the current observational limit offer a possible but problematic resolution to the discrepancy. We discuss several other possibilities: that the present population of JFCs is a large fluctuation above their long term average, that larger scattered disk objects tidally break-up into multiple fragments during close planetary encounters as their orbits evolve from the trans-Neptune zone to near Jupiter, or that there are alternative source populations that contribute significantly to the JFCs. Well-characterized observational investigations of the Centaurs, objects that are transitioning between the trans-Neptune Kuiper belt region and the inner solar system, can test the predictions of the non-steady state and the tidal break-up hypotheses. The classical and resonant classes of the Kuiper belt are worth re-consideration as significant additional or alternate sources of the JFCs.Comment: 33 pages, 6 figures. Revised Content. To be published in The Astrophysical Journa

Distinguishing wet from dry age-related macular degeneration using three-dimensional computer-automated threshold Amsler grid testing

Background/aims: With the increased efficacy of current therapy for wet age-related macular degeneration (AMD), better ways to detect wet AMD are needed. This study was designed to test the ability of three-dimensional contrast threshold Amsler grid (3D-CTAG) testing to distinguish wet AMD from dry AMD. Methods: Conventional paper Amsler grid and 3D-CTAG tests were performed in 90 eyes: 63 with AMD (34 dry, 29 wet) and 27 controls. Qualitative comparisons were based upon the three-dimensional shapes of central visual field (VF) defects. Quantitative analyses considered the number and volume of the three-dimensional defects. Results: 25/34 (74%) dry AMD and 6/29 (21%) wet AMD eyes had no distortions on paper Amsler grid. Of these, 5/25 (20%) dry and 6/6 (100%) wet (p=0.03) AMD eyes exhibited central VF defects with 3D-CTAG. Wet AMD displayed stepped defects in 16/28 (57%) eyes, compared with only 2/34 (6%) of dry AMD eyes (p=0.002). All three volumetric indices of VF defects were two- to four-fold greater in wet than dry AMD (p<0.006). 3D-CTAG had 83.9% positive and 90.6% negative predictive values for wet AMD. Conclusions: 3D-CTAG has a higher likelihood of detecting central VF defects than conventional Amsler grid, especially in wet AMD. Wet AMD can be distinguished from dry AMD by qualitative and quantitative 3D-CTAG criteria. Thus, 3D-CTAG may be useful in screening for wet AMD, quantitating disease severity, and providing a quantitative outcome measure of therapy

Applications of Support Vector Machines as a Robust tool in High Throughput Virtual Screening

Chemical space is enormously huge but not all of it is pertinent for the drug designing. Virtual screening methods act as knowledge-based filters to discover the coveted novel lead molecules possessing desired pharmacological properties. Support Vector Machines (SVM) is a reliable virtual screening tool for prioritizing molecules with the required biological activity and minimum toxicity. It has to its credit inherent advantages such as support for noisy data mainly coming from varied high-throughput biological assays, high sensitivity, specificity, prediction accuracy and reduction in false positives. SVM-based classification methods can efficiently discriminate inhibitors from non-inhibitors, actives from inactives, toxic from non-toxic and promiscuous from non-promiscuous molecules. As the principles of drug design are also applicable for agrochemicals, SVM methods are being applied for virtual screening for pesticides too. The current review discusses the basic kernels and models used for binary discrimination and also features used for developing SVM-based scoring functions, which will enhance our understanding of molecular interactions. SVM modeling has also been compared by many researchers with other statistical methods such as Artificial Neural Networks, k-nearest neighbour (kNN), decision trees, partial least squares, etc. Such studies have also been discussed in this review. Moreover, a case study involving the use of SVM method for screening molecules for cancer therapy has been carried out and the preliminary results presented here indicate that the SVM is an excellent classifier for screening the molecules

Myocardial infarct extension during reperfusion after coronary artery occlusion: Pathologic evidence

AbstractObjectives. The goal of this study was to demonstrate myocardial infarct extension during reperfusion within the same animal.Background. Whether myocardial reperfusion can result in the extension of myocardial necrosis remains controversial. The transformation of reversibly injured myocytes into irreversibly damaged cells after reperfusion has been difficult to demonstrate pathologically.Methods. New Zealand White rabbits (Group I, n = 10) were subjected to 30 min of coronary artery occlusion and 180 min of reperfusion. Horseradish peroxidase, a tracer protein that permeates the sarcolemma of irreversibly injured myocytes, was used to quantitate myocyte necrosis at the beginning of reperfusion. Within the same heart, infarct size was measured after 180 min of reperfusion by triphenyttetrazolium chloride (TTC) staining. In separate experiments to demonstrate the validity of the model, rabbits were subjected to 30 min of coronary occlusion, followed by intravenous infusion of horseradish peroxidase and rapid induction of death (Group II) or 30 min of occlusion, 180 min of reperfusion with horseradish peroxidase administered after 180 min of reperfusion and TTC staining after induced death (Group III).Results. In Group I, infarct size at the onset of reperfusion, delineated by horseradish peroxidase, measured 45.3 ± 2.8% of the area of risk and was significantly less than TTC-delineated infarct size after 189 min of re perfusion (59.8 ± 33%, p = 0.0002). By electron microscopy, border areas within the ischemic bed demonstrated irreversibly injured horseradish peroxidasepositive myocytes adjacent to irreversibly injured horseradish peroxidase-negative myocytes, suggesting that farther cell death occurred during reperfusion. In Group II, infarcts delineated by horseradish peroxidase after 30 min of coronary occlusion were similar in size to infarcts measured by this tracer in Group I. In Group III, infarcts delineated by horseradish peroxidase at 180 min of reperfusion were similar in size to infarcts measured by TTC and similar to TTC-delineated infarcts measured at 180 min of reperfusion in Group I.Conclusions. These results provide evidence that there is a subset of myocytes in border areas within the ischemic region that are viable at the beginning of reperfusion but subsequently progress to irreversible injury during the reperfusion period

The Classical Sumudu Transform and its q-Image of the Most Generalized Hypergeometric and Wright-Type Hypergeometric Functions

The q- Calculus has served as a bridge between mathematics and physics, particularly in case of quantum physics. The q-generalizations of mathematical concepts like Laplace, Fourier and Sumudu transforms, Hypergeometric functions etc. can be advantageously used in solution of various problems arising in the field of physical and engineering sciences. The q-Sumudu transform, the q-image of classical Sumudu transform is the theoretical dual of the q-Laplace transform. In view of this, the present paper deals with some of the important applications of classical Sumudu and q-Sumudu transform of generalized hypergeometric function and Wright-type hypergeometric function. The results have been presented in terms of well-known Fox’s H-function. Some special cases have also been discussed

Signatures of Planets in Spatially Unresolved Disks

Main sequence stars are commonly surrounded by debris disks, composed of cold dust continuously replenished by a reservoir of undetected dust-producing planetesimals. In a planetary system with a belt of planetesimals (like the Solar System's Kuiper Belt) and one or more interior giant planets, the trapping of dust particles in the mean motion resonances with the planets can create structure in the dust disk, as the particles accumulate at certain semimajor axes. Sufficiently massive planets may also scatter and eject dust particles out of a planetary system, creating a dust depleted region inside the orbit of the planet. In anticipation of future observations of spatially unresolved debris disks with the Spitzer Space Telescope, we are interested in studying how the structure carved by planets affects the shape of the disk's spectral energy distribution (SED), and consequently if the SED can be used to infer the presence of planets. We numerically calculate the equilibrium spatial density distributions and SEDs of dust disks originated by a belt of planetesimals in the presence of interior giant planets in different planetary configurations, and for a representative sample of chemical compositions. The dynamical models are necessary to estimate the enhancement of particles near the mean motion resonances with the planets, and to determine how many particles drift inside the planet's orbit. Based on the SEDs and predicted $\it{Spitzer}$ colors we discuss what types of planetary systems can be distinguishable from one another and the main parameter degeneracies in the model SEDs.Comment: 40 pages (pre-print form), including 16 figures. Published in ApJ 200

Twin plane re-entrant mechanism for catalytic nanowire growth.

A twin-plane based nanowire growth mechanism is established using Au catalyzed Ge nanowire growth as a model system. Video-rate lattice-resolved environmental transmission electron microscopy shows a convex, V-shaped liquid catalyst-nanowire growth interface for a ⟨112⟩ growth direction that is composed of two Ge {111} planes that meet at a twin boundary. Unlike bulk crystals, the nanowire geometry allows steady-state growth with a single twin boundary at the nanowire center. We suggest that the nucleation barrier at the twin-plane re-entrant groove is effectively reduced by the line energy, and hence the twin acts as a preferential nucleation site that dictates the lateral step flow cycle which constitutes nanowire growth.S. H. acknowledges funding from ERC grant InsituNANO (project number 279342). A. D. G. acknowledges funding from the Marshall Aid Commemoration Commission and the National Science Foundation. C. D. acknowledge funding from the Royal Society. P.V. acknowledges the support of ONR grant N00014-12-1-0198. We gratefully acknowledge the use of facilities within the LeRoy Eyring Center for Solid State Science at Arizona State University.This document is the Accepted Manuscript version of a Published Work that appeared in final form in Nano Letters, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/doi/abs/10.1021/nl404244u. (AD Gamalski, PW Voorhees, C Ducati, R Sharma, S Hofmann, Nano Letters 2014, 14, 1288–1292