50,877 research outputs found
High stability amplifier
An electrical RF signal amplifier for providing high temperature stability and RF isolation and comprised of an integrated circuit voltage regulator, a single transistor, and an integrated circuit operational amplifier mounted on a circuit board such that passive circuit elements are located on side of the circuit board while the active circuit elements are located on the other side is described. The active circuit elements are embedded in a common heat sink so that a common temperature reference is provided for changes in ambient temperature. The single transistor and operational amplifier are connected together to form a feedback amplifier powered from the voltage regulator with transistor implementing primarily the desired signal gain while the operational amplifier implements signal isolation. Further RF isolation is provided by the voltage regulator which inhibits cross-talk from other like amplifiers powered from a common power supply. Input and output terminals consisting of coaxial connectors are located on the sides of a housing in which all the circuit components and heat sink are located
High torque bellows seal rotary drive
Bellows seal rotary drive device was developed which allows high torque transmission through sealed compartments. Bearing friction which would normally be carried by sealing bellows in comparable devices is absorbed by universal-gimbal joint. It can be used to transmit high torque, low speed, rotary motion through sealed barriers to prevent contamination or escape of fluids
Relationships of Job and Family Involvement, Family Social Support, and Work–Family Conflict with Job and Life Satisfaction
A model of the relationship between work and family that incorporates variables from both the work-family conflict and social support literatures was developed and empirically tested. This model related bidirectional work-family conflict, family instrumental and emotional social support, and job and family involvement to job and life satisfaction. Data came from 163 workers who were living with at least 1 family member. Results suggested that relationships between work and family can have an important effect on job and life satisfaction and that the level of involvement the worker assigns to work and family roles is associated with this relationship. The results also suggested that the relationship between work and family can be simultaneously characterized by conflict and support. Higher levels of work interfering with family predicted lower levels of family emotional and instrumental support. Higher levels of family emotional and instrumental support were associated with lower levels of family interfering with work. (PsycINFO Database Record (c) 2013 APA, all rights reserved)
Hexagonal spiral growth in the absence of a substrate
Experiments on the formation of spiraling hexagons (350 - 1000 nm in width)
from a solution of nanoparticles are presented. Transmission electron
microscopy images of the reaction products of chemically synthesized cadmium
nanocrystals indicate that the birth of the hexagons proceeds without
assistance from static screw or edge dislocatons, that is, they spiral without
constraints provided by an underlying substrate. Instead, the apparent growth
mechanism relies on what we believe is a dynamical dislocation identified as a
dense aggregate of small nanocrystals that straddles the spiraling hexagon at
the crystal surface. This nanocrystal bundle, which we term the "feeder", also
appears to release nanocrystals into the spiral during the growth process.Comment: 4 pages, 5 figure
Parameters for Twisted Representations
The study of Hermitian forms on a real reductive group gives rise, in the
unequal rank case, to a new class of Kazhdan-Lusztig-Vogan polynomials. These
are associated with an outer automorphism of , and are related to
representations of the extended group . These polynomials were
defined geometrically by Lusztig and Vogan in "Quasisplit Hecke Algebras and
Symmetric Spaces", Duke Math. J. 163 (2014), 983--1034. In order to use their
results to compute the polynomials, one needs to describe explicitly the
extension of representations to the extended group. This paper analyzes these
extensions, and thereby gives a complete algorithm for computing the
polynomials. This algorithm is being implemented in the Atlas of Lie Groups and
Representations software
Accelerated Overlap Fermions
Numerical evaluation of the overlap Dirac operator is difficult since it
contains the sign function of the Hermitian Wilson-Dirac
operator with a negative mass term. The problems are due to having
very small eigenvalues on the equilibrium background configurations generated
in current day Monte Carlo simulations. Since these are a consequence of the
lattice discretisation and do not occur in the continuum version of the
operator, we investigate in this paper to what extent the numerical evaluation
of the overlap can be accelerated by making the Wilson-Dirac operator more
continuum-like. Specifically, we study the effect of including the clover term
in the Wilson-Dirac operator and smearing the link variables in the irrelevant
terms. In doing so, we have obtained a factor of two speedup by moving from the
Wilson action to a FLIC (Fat Link Irrelevant Clover) action as the overlap
kernel.Comment: 15 pages, 6 figures; V2 contains major revision of the introduction
and motivation sections. Conclusion and results unchanged v2.1: formatting
chang
The memory space: Exploring future uses of Web 2.0 and mobile internet through design interventions.
The QuVis Quantum Mechanics Visualization project aims to address challenges
of quantum mechanics instruction through the development of interactive
simulations for the learning and teaching of quantum mechanics. In this
article, we describe evaluation of simulations focusing on two-level systems
developed as part of the Institute of Physics Quantum Physics resources.
Simulations are research-based and have been iteratively refined using student
feedback in individual observation sessions and in-class trials. We give
evidence that these simulations are helping students learn quantum mechanics
concepts at both the introductory and advanced undergraduate level, and that
students perceive simulations to be beneficial to their learning.Comment: 15 pages, 5 figures, 1 table; accepted for publication in the
American Journal of Physic
Flight/ground sample comparison relating to flight experiment M552, exothermic brazing
Comparisons were made between Skylab and ground-based specimens of nickel and stainless steel which were vacuum brazed using silver-copper-lithium alloy with various joint configurations. It was established that the absence of gravity greatly extends the scope of brazing since capillary flow can proceed without gravity interference. There was also evidence of enhanced transport, primarily in that liquid silver copper alloy dissolves nickel to a much greater extent in the zero gravity environment
Resilience–Recovery Factors in Post-traumatic Stress Disorder Among Female and Male Vietnam Veterans: Hardiness, Postwar Social Support, and Additional Stressful Life Events
Structural equation modeling procedures were used to examine relationships among several war zone stressor dimensions, resilience-recovery factors, and post-traumatic stress disorder symptoms in a national sample of 1,632 Vietnam veterans (26% women and 74% men). A 9-factor measurement model was specified on a mixed-gender subsample of the data and then replicated on separate subsamples of female and male veterans. For both genders, the structural models supported strong mediation effects for the intrapersonal resource characteristic of hardiness, postwar structural and functional social support, and additional negative life events in the postwar period. Support for moderator effects or buffering in terms of interactions between war zone stressor level and resiliencerecovery factors was minimal
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