11,908 research outputs found

    Unified powered flight guidance

    Get PDF
    A complete revision of the orbiter powered flight guidance scheme is presented. A unified approach to powered flight guidance was taken to accommodate all phases of exo-atmospheric orbiter powered flight, from ascent through deorbit. The guidance scheme was changed from the previous modified version of the Lambert Aim Point Maneuver Mode used in Apollo to one that employs linear tangent guidance concepts. This document replaces the previous ascent phase equation document

    Coexistence of Antiferromagnetism and Superconductivity in Electron-doped High-Tc Superconductors

    Full text link
    We present magnetotransport evidence for antiferromagnetism in films of the electron-doped cuprates Pr2x_{2-x}Cex_xCuO4_4. Our results show clear signature of static antiferromagnetism up to optimal doping x=0.15, with a quantum phase transition close to x=0.16, and a coexistence of static antiferromagnetism and superconductivity for 0.12\lex\le0.15

    Associations between children's diet quality and watching television during meal or snack consumption: a systematic review

    Get PDF
    Studies have identified an association between watching television (TV) and childhood obesity. This review adds context to existing research by examining the associations between TV viewing, whilst eating, and children's diet quality. Web of Science and PubMed databases were searched from January 2000 to June 2014. Cross-sectional trials of case control or cohort studies, which included baseline data, measuring the associations between eating whilst watching TV and children's food and drink intake. Quality of selected papers was assessed. Thirteen studies, representing 61,674 children aged 1–18 yrs, met inclusion criteria. Of six studies reporting overall food habits, all found a positive association between TV viewing and consumption of pizza, fried foods, sweets, and snacks. Of eight studies looking at fruit and vegetable consumption, seven identified a negative association with eating whilst watching TV (p < .0001). Four out of five studies identified a positive association between watching TV whilst eating and servings of sugar-sweetened beverages (p < .0001). Four studies identified an association between low socioeconomic status and increased likelihood of eating whilst watching TV (p ≤ .01). Family meals did not overcome the adverse impact on diet quality of having the TV on at mealtimes. Eating whilst watching television is associated with poorer diet quality among children, including more frequent consumption of sugar-sweetened beverages and high-fat, high-sugar foods and fewer fruits and vegetables. Although these differences in consumption are small, the cumulative effect may contribute to the positive association between eating whilst watching TV and childhood obesity

    Slow plasmon modes in polymeric salt solutions

    Full text link
    The dynamics of polymeric salt solutions are presented. The salt consists of chains A\rm A and B\rm B, which are chemically different and interact with a Flory-interaction parameter χ\chi, the A\rm A chain ends carry a positive charge whereas the B\rm B chain ends are modified by negative charges. The static structure factor shows a peak corresponding to a micro phase separation. At low momentum transfer, the interdiffusion mode is driven by electrostatics and is of the plasmon-type, but with an unusually low frequency, easily accessible by experiments. This is due to the polymer connectivity that introduces high friction and amplifies the charge scattering thus allowing for low charge densities. The interdiffusion mode shows a minimum (critical slowing down) at finite kk when the interaction parameter increases we find then a low kk frequency quasi-plateau.Comment: accepted in Europhys. Let

    Infinite partition monoids

    Full text link
    Let PX\mathcal P_X and SX\mathcal S_X be the partition monoid and symmetric group on an infinite set XX. We show that PX\mathcal P_X may be generated by SX\mathcal S_X together with two (but no fewer) additional partitions, and we classify the pairs α,βPX\alpha,\beta\in\mathcal P_X for which PX\mathcal P_X is generated by SX{α,β}\mathcal S_X\cup\{\alpha,\beta\}. We also show that PX\mathcal P_X may be generated by the set EX\mathcal E_X of all idempotent partitions together with two (but no fewer) additional partitions. In fact, PX\mathcal P_X is generated by EX{α,β}\mathcal E_X\cup\{\alpha,\beta\} if and only if it is generated by EXSX{α,β}\mathcal E_X\cup\mathcal S_X\cup\{\alpha,\beta\}. We also classify the pairs α,βPX\alpha,\beta\in\mathcal P_X for which PX\mathcal P_X is generated by EX{α,β}\mathcal E_X\cup\{\alpha,\beta\}. Among other results, we show that any countable subset of PX\mathcal P_X is contained in a 44-generated subsemigroup of PX\mathcal P_X, and that the length function on PX\mathcal P_X is bounded with respect to any generating set

    An examination of the effects of self-regulatory focus on the perception of the media richness: the case of email

    Get PDF
    Communication is a key element in organizations’ business success. The media richness theory and the channel expansion theory are two of the most influential theories regarding the selection and use of communication media in organizations; however, literature has focused little on the effects of self-regulation by managers and employees in these theories. To analyze these topics, this study develops an empirical investigation by gathering data from 600 managers and employees using a questionnaire. The results suggest that the perception of media richness is positively affected when the individual shows a promotion focus or strategy.Peer ReviewedPostprint (author’s final draft

    Phase Separation in Binary Fluid Mixtures with Continuously Ramped Temperature

    Full text link
    We consider the demixing of a binary fluid mixture, under gravity, which is steadily driven into a two phase region by slowly ramping the temperature. We assume, as a first approximation, that the system remains spatially isothermal, and examine the interplay of two competing nonlinearities. One of these arises because the supersaturation is greatest far from the meniscus, creating inversion of the density which can lead to fluid motion; although isothermal, this is somewhat like the Benard problem (a single-phase fluid heated from below). The other is the intrinsic diffusive instability which results either in nucleation or in spinodal decomposition at large supersaturations. Experimental results on a simple binary mixture show interesting oscillations in heat capacity and optical properties for a wide range of ramp parameters. We argue that these oscillations arise under conditions where both nonlinearities are important
    corecore