13,853 research outputs found
Baryogenesis at the Electroweak Phase Transition for a SUSY Model with a Gauge Singlet
SUSY models with a gauge singlet easily allow for a strongly first order
electroweak phase transition (EWPT). We discuss the wall profile, in particular
transitional CP violation during the EWPT. We calculate CP violating source
terms for the charginos in the WKB approximation and solve the relevant
transport equations to obtain the generated baryon asymmetry.Comment: 5 pages, 6 figures. To appear in the Proceedings of Strong and
Electroweak Matter 2000 (SEWM2000), Marseilles; a reference adde
Consideration of space applications transfer centers for the NASA office of applications
The concept of Space Applications Transfer Centers is examined to consider the design of the first of these facilities. The questions to be considered are listed
A survey of users of earth resources remote sensing data
The results of a NASA supported Battelle survey to obtain user views on the nature and value of LANDSAT data use, on current LANDSAT capabilities, and on ways to improve data use were summarized. Questionnaire and interview responses from over 1000 private and public sector users were analyzed and discussed
A Tachyonic Gluon Mass: Between Infrared and Ultraviolet
The gluon spin coupling to a Gaussian correlated background gauge field
induces an effective tachyonic gluon mass. It is momentum dependent and
vanishes in the UV only like 1/p^2. In the IR, we obtain stabilization through
a positive m^2_{conf}(p^2) related to confinement. Recently a purely
phenomenological tachyonic gluon mass was used to explain the linear rise in
the q\bar q static potential at small distances and also some long standing
discrepancies found in QCD sum rules. We show that the stochastic vacuum model
of QCD predicts a gluon mass with the desired properties.Comment: 10 pages LaTeX, 2 figures using eps
Survey of users of earth resources remote sensing data
A user survey was conducted to determine current earth resources survey (ERS) data use/user status and recommendations for strengthening use. Only high-altitude aircraft and satellite (primarily LANDSAT) data were included. Emphasis was placed on the private sector/industrial user. Objectives of the survey included: who is using ERS data, how they are using the data, the relative value of current data use as well as obtaining user views as to possible ways of strengthening future ERS data use. The survey results are documented and should provide relevant decision making information for developing future programs of maximum benefit to all end users of satellite ERS data
Mixing and condensation in a wet granular medium
We have studied the effect of small amounts of added liquid on the dynamic
behavior of a granular system consisting of a mixture of glass beads of two
different sizes. Segregation of the large beads to the top of the sample is
found to depend in a nontrivial way on the liquid content. A transition to
viscoplastic behavior occurs at a critical liquid content, which depends upon
the bead size. We show that this transition can be interpreted as a
condensation due to the hysteretic liquid bridge forces connecting the beads,
and provide the corresponding phase diagram.Comment: submitted to PR
Direct contact and authoritarianism as moderators between extended contact and reduced prejudice: Lower threat and greater trust as mediators
Using a representative sample of Dutch adults (N = 1238), we investigated the moderating influence of direct contact and authoritarianism on the potential of extended contact to reduce prejudice. As expected, direct contact and authoritarianism moderated the effect of extended contact on prejudice. Moreover, the third-order moderation effect was also significant, revealing that extended contact has the strongest effect among high authoritarians with low levels of direct contact. We identified trust and perceived threat as the mediating processes underlying these moderation effects. The present study thus attests to the theoretical and practical relevance of reducing prejudice via extended contact. The discussion focuses on the role of extended contact in relation to direct contact and authoritarianism as well as on the importance of trust in intergroup contexts
Exploring structural and electronic effects in three isomers of tris{bis(trifluoromethyl)phenyl}borane: Towards the combined electrochemical-frustrated Lewis pair activation of H2
Three structural isomers of tris{bis(trifluoromethyl)phenyl}borane have been studied as the acidic com- ponent of frustrated Lewis pairs. While the 3,5-substituted isomer is already known to heterolytically cleave H2 to generate a bridging-hydride; ortho-substituents in the 2,4- and 2,5-isomers quench such reactivity through electron donation into the vacant boron pz orbital and steric blocking of the boron centre; as shown by electrochemical, structural and computational studies. Electrochemical studies of the corresponding borohydrides identify that the two-electron oxidation of terminal-hydrides occurs at more positive potentials than observed for [HB(C6F5)3]−, while the bridging-hydride oxidizes at a higher poten- tial still, comparable to that of free H2
Targeted expression of truncated glued disrupts giant fiber synapse formation in Drosophila
Glued1 (Gl1) mutants produce a truncated protein that acts as a poison subunit and disables the cytoplasmic retrograde motor dynein. Heterozygous mutants have axonal defects in the adult eye and the nervous system. Here we show that selective expression of the poison subunit in neurons of the giant fiber (GF) system disrupts synaptogenesis between the GF and one of its targets, the tergotrochanteral motorneuron (TTMn). Growth and pathfinding by the GF axon and the TTMn dendrite are normal, but the terminal of the GF axon fails to develop normally and becomes swollen with large vesicles. This is a presynaptic defect because expression of truncated Glued restricted to the GF results in the same defect. When tested electrophysiologically, the flies with abnormal axons show a weakened or absent GF-TTMn connection. In Glued1 heterozygotes, GF-TTMn synapse formation appears morphologically normal, but adult flies show abnormal responses to repetitive stimuli. This physiological effect is also observed when tetanus toxin is expressed in the GFs. Because the GF-TTMn is thought to be a mixed electrochemical synapse, the results show that Glued has a role in assembling both the chemical and electrical components. We speculate that disrupting transport of a retrograde signal disrupts synapse formation and maturation
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