Waves as the source of apparent twisting motions in sunspot penumbrae

The motion of dark striations across bright filaments in a sunspot penumbra has become an important new diagnostic of convective gas flows in penumbral filaments. The nature of these striations has, however, remained unclear. Here we present an analysis of small scale motions in penumbral filaments in both simulations and observations. The simulations, when viewed from above, show fine structure with dark lanes running outwards from the dark core of the penumbral filaments. The dark lanes either occur preferentially on one side or alternate between both sides of the filament. We identify this fine structure with transverse (kink) oscillations of the filament, corresponding to a sideways swaying of the filament. These oscillations have periods in the range of 5-7 min and propagate outward and downward along the filament. Similar features are found in observed G-band intensity time series of penumbral filaments in a sunspot located near disk center obtained by the Broadband Filter Imager (BFI) on board {\it Hinode}. We also find that some filaments show dark striations moving to both sides of the filaments. Based on the agreement between simulations and observations we conclude that the motions of these striations are caused by transverse oscillations of the underlying bright filaments.Comment: Accepted for publication in Astrophysical Journal on 8th April 201

Enhanced Joule Heating in Umbral Dots

We present a study of magnetic profiles of umbral dots (UDs) and its consequences on the Joule heating mechanisms. Hamedivafa (2003) studied Joule heating using vertical component of magnetic field. In this paper UDs magnetic profile has been investigated including the new azimuthal component of magnetic field which might explain the relatively larger enhancement of Joule heating causing more brightness near circumference of UD.Comment: 8 pages, 1 figure, accepted in Solar Physic

Price Promotions Are Inherently More Arousing for Interdependents

The ubiquity of promotions and price discounts has prompted much research to understand how consumers respond to deals. In this research, we present an affective perspective for why some consumers may be more deal prone than others. Specifically, we propose that for interdependents (vs. independents), chancing upon a deal leads to heightened arousal and greater purchase intention for the discounted product. We further propose that this effect arises because interdependents (vs. independents) are more likely to possess a comparative mindset. Findings from five studies provide converging evidence to support our propositions. Across the studies, we adopt different operationalizations of self-construal (via country, cultural prime, self-construal scale and prime), measures of arousal (skin conductance and self-report measures) and use different product categories. We further show that when a comparative mindset is made salient for independents and interdependents, the observed effect dissipates

Bridging interactions of proteins with silica nanoparticles: The influence of pH, ionic strength and protein concentration

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Charge-driven bridging of nanoparticles by macromolecules represents a promising route for engineering functional structures, but the strong electrostatic interactions involved when using conventional polyelectrolytes impart irreversible complexation and ill-defined structures. Recently it was found that the electrostatic interaction of silica nanoparticles with small globular proteins leads to aggregate structures that can be controlled by pH. Here we study the combined influence of pH and electrolyte concentration on the bridging aggregation of silica nanoparticles with lysozyme in dilute aqueous dispersions. We find that protein binding to the silica particles is determined by pH irrespective of the ionic strength. The hetero-aggregate structures formed by the silica particles with the protein were studied by small-angle X-ray scattering (SAXS) and the structure factor data were analyzed on the basis of a short-range square-well attractive pair potential (close to the sticky-hard-sphere limit). It is found that the electrolyte concentration has a strong influence on the stickiness near pH 5, where the weakly charged silica particles are bridged by the strongly charged protein. An even stronger influence of the electrolyte is found in the vicinity of the isoelectric point of the protein (pI = 10.7) and is attributed to shielding of the repulsion between the highly charged silica particles and hydrophobic interactions between the bridging protein molecules.DFG, GRK 1524, Self-Assembled Soft-Matter Nanostructures at Interface

Surfactant adsorption and aggregate structure at silica nanoparticles: Effects of particle size and surface modification

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.The influence of particle size and a surface modifier on the self-assembly of the nonionic surfactant C12E5 at silica nanoparticles was studied by adsorption measurements and small-angle neutron scattering (SANS). Silica nanoparticles of diameter 13 to 43 nm were synthesized involving the basic amino acid lysine. A strong decrease of the limiting adsorption of C12E5 with decreasing particle diameter was found. To unveil the role of lysine as a surface modifier for the observed size dependence of surfactant adsorption, the morphology of the surfactant aggregates assembled on pure siliceous nanoparticles (Ludox-TMA, 27 nm) and their evolution with increasing lysine concentration at a fixed surfactant-to-silica ratio was studied by SANS. In the absence of lysine, the surfactant forms surface micelles at silica particles. As the concentration of lysine is increased, a gradual transition from the surface micelles to detached wormlike micelles in the bulk solution is observed. The changes in surfactant aggregate morphology cause pronounced changes of the system properties, as is demonstrated by turbidity measurements as a function of temperature. These findings are discussed in terms of particle surface curvature and surfactant binding strength, which present new insight into the delicate balance between the two properties.EC/FP7/226507/EU/Integrated Infrastructure Initiative for Neutron Scattering and Muon Spectroscopy/NMI3DFG, GRK 1524, Self-Assembled Soft-Matter Nanostructures at Interface

Characteristic Dependence of Umbral Dots on their Magnetic Structure

Umbral dots (UDs) were observed in a stable sunspot in NOAA 10944 by the Hinode Solar Optical Telescope on 2007 March 1. The observation program consisted of blue continuum images and spectropolarimetric profiles of Fe I 630 nm line. An automatic detection algorithm for UDs was applied to the 2-hour continuous blue continuum images, and using the obtained data, the lifetime, size, and proper motion of UDs were calculated. The magnetic structure of the sunspot was derived through the inversion of the spectropolarimetric profiles. We calculated the correlations between UD's parameters (size, lifetime, occurrence rate, proper motion) and magnetic fields (field strength, inclination, azimuth), and obtained the following results: (1) Both the lifetime and size of UDs are almost constant regardless of the magnetic field strength at their emergence site. (2) The speed of UDs increases as the field inclination angle at their emergence site gets larger. (3) The direction of movement of UDs is nearly parallel to the direction of the horizontal component of magnetic field in the region with strongly inclined field, while UDs in the region with weakly inclined field show virtually no proper motion. Our results describe the basic properties of magnetoconvection in sunspots. We will discuss our results in comparison to recent MHD simulations by Schussler & Vogler (2006) and Rempel et al. (2009).Comment: 22 pages, 10 figures, accepted for publication in Ap

A New Species of Vollenhovia (Hymenoptera, Formicidae) From India with Key to Known Indian Species

Vollenhovia gastropunctata Bharti et Kumar, sp. n. (Hymenoptera, Formicidae) is described and illustrated based on the worker caste from India. A key to the Indian species of Vollenhovia Mayr, 1865 is provided.Иллюстрированное описание Vollenhovia gastropunctata Bharti et Kumar, sp. n. (Hymenoptera, Formicidae) по рабочим особям из Индии. Составлена таблица для определения видов рода Vollenhovia Mayr, 1865, обитающих в Индии

Echinopla cherapunjiensis sp. n. (Hymenoptera, Formicidae) from India

Echinopla cherapunjiensis Bharti et Gul, sp. n. is described from India. This represents the second species of genus reported in India, with only Echinopla lineata senilis Mayr, 1862 described earlier from Nicobar Islands. The species distinctly differs from all other known species of this genus by the following combination of characters: globose shape of head, presence of seven teeth on petiolar scale, flat dorsum of mesosoma with promesonotal and mesometanotal sutures obsolete, whole body surface (dorsum) rough due to sinuous sculpture, deep excavations and spiky elevations on head and mesosoma and excavations on gaster.Echinopla cherapunjiensis Bharti et Gul, sp. n. описан из Индии. Это второй представитель рода, обнаруженный в Индии, вместе с видом Echinopla lineata senilis Mayr, 1862, описанный ранее с Никобарских островов. Этот вид четко отличается от всех других известных видов этого рода рядом признаков: шаровидной головой, наличием семи зубцов на петиолярном сегменте, плоской брюшной частью с промезонотальным и мезометанотальным рудиментарным швом, шероховатой дорсальной поверхностью тела благодаря волнистой скульптуре, глубокими выемкам и шиповидными выпуклостями на голове и мезосоме, а также выемками на брюшке

First Record of the Genus Myopias (Hymenoptera, Formicidae) from India, with Description of New Species

Myopias shivalikensis Bharti et Wachkoo, sp. n. is described based on a single worker, collected in lower Shivalik range (700 m a. s. l.) of Northwest Himalaya by soil core method. The genus Myopias is recorded for the first time in India. M. shivalikensis is a cryptobiotic species with reduced body size and rudimentary eyes. It is similar to M. nops Willey et Brown, 1983, distinctly differing from all described species of this genus.Myopias shivalikensis Bharti et Wachkoo, sp. n. описан по единственному рабочему, найденному в нижней части хребта Шивалик (700 м над у. м.) в северо-западных Гималаях в почвенных пробах. Это первая находка рода Myopias в Индии. Данный вид является криптобионтом и характеризуется мелкими размерами и редуцированными глазами. Он наиболее сходен с M. nops Willey et Brown, 1983 и хорошо отличается от всех ранее описанных видов этого рода

Clinicoepidemiological study of fixed drug eruption in tertiary care hospital

Background: Adverse cutaneous drug reactions pose diagnostic difficulties due to a varied clinical manifestations and broad categories of causative agents. Fixed drug eruptions (FDE) are one of them. Present study aims i) to record various clinical features of FDE, their causative agents and ii) to study the pattern of morbidity in patients with FDE in a tertiary care hospital, Rajkot, Gujarat, India.Methods: The 88 patients with FDEs attending department of dermatology, venereology and leprosy at PDU govt. medical college and hospital, Rajkot, Gujarat from September 2018 to September 2020 were included after informed consent. After taking thorough history, complete blood count and biochemical tests were done. HIV testing was done in severe reactions with generalised involvement. Appropriate treatment was given with counselling regarding the offending drug for prevention of reaction in future.Results: The male patients were more affected than female patients with M: F ratio of 1.3:1. The most common age group affected was 21-30 years (22.7%). Antimicrobials were the most common offending drugs (43.2%). None of the patients were HIV reactive in our study. No mortality was reported in our study.Conclusions: The patterns of FDE and the causative drugs are remarkably different in our study. Knowledge of patterns and the causative agents helps in prevention of same reactions in future in patients