4,460 research outputs found
Frequency noise and intensity noise of next-generation gravitational-wave detectors with RF/DC readout schemes
The sensitivity of next-generation gravitational-wave detectors such as
Advanced LIGO and LCGT should be limited mostly by quantum noise with an
expected technical progress to reduce seismic noise and thermal noise. Those
detectors will employ the optical configuration of resonant-sideband-extraction
that can be realized with a signal-recycling mirror added to the Fabry-Perot
Michelson interferometer. While this configuration can reduce quantum noise of
the detector, it can possibly increase laser frequency noise and intensity
noise. The analysis of laser noise in the interferometer with the conventional
configuration has been done in several papers, and we shall extend the analysis
to the resonant-sideband-extraction configuration with the radiation pressure
effect included. We shall also refer to laser noise in the case we employ the
so-called DC readout scheme.Comment: An error in Fig. 10 in the published version in PRD has been
corrected in this version; an erratum has been submitted to PRD. After
correction, this figure reflects a significant difference in the ways RF and
DC readout schemes are susceptible to laser noise. In addition, the levels of
mirror loss imbalances and input laser amplitude noise have also been updated
to be more realistic for Advanced LIG
Trust and privacy in distributed work groups
Proceedings of the 2nd International Workshop on Social Computing, Behavioral Modeling and PredictionTrust plays an important role in both group cooperation and economic exchange. As new technologies emerge for communication and exchange, established mechanisms of trust are disrupted or distorted, which can lead to the breakdown of cooperation or to increasing fraud in exchange. This paper examines whether and how personal privacy information about members of distributed work groups influences individuals' cooperation and privacy behavior in the group. Specifically, we examine whether people use others' privacy settings as signals of trustworthiness that affect group cooperation. In addition, we examine how individual privacy preferences relate to trustworthy behavior. Understanding how people interact with others in online settings, in particular when they have limited information, has important implications for geographically distributed groups enabled through new information technologies. In addition, understanding how people might use information gleaned from technology usage, such as personal privacy settings, particularly in the absence of other information, has implications for understanding many potential situations that arise in pervasively networked environments.Preprin
Induced Anticlinic Ordering and Nanophase Segregation of Bow-Shaped Molecules in a Smectic Solvent
Recent experiments indicate that doping low concentrations of bent-core
molecules into calamitic smectic solvents can induce anticlinic and biaxial
smectic phases. We have carried out Monte Carlo (MC) simulations of mixtures of
rodlike molecules (hard spherocylinders with length/breadth ratio ) and bow- or banana-shaped molecules (hard spherocylinder dimers
with length/breadth ratio or 2.5 and opening angle ) to
probe the molecular-scale organization and phase behavior of rod/banana
mixtures. We find that a low concentration (3%) of dimers
induces anticlinic (SmC) ordering in an untilted smectic (SmA) phase for
. For smaller , half of each bow-shaped
molecule is nanophase segregated between smectic layers, and the smectic layers
are untilted. For , no tilted phases are induced. However,
with decreasing we observe a sharp transition from {\sl intralamellar}
nanophase segregation (bow-shaped molecules segregated within smectic layers)
to {\sl interlamellar} nanophase segregation (bow-shaped molecules concentrated
between smectic layers) near . These results demonstrate that
purely entropic effects can lead to surprisingly complex behavior in rod/banana
mixtures.Comment: 5 pages Revtex, 7 postscript figure
Bounds on gravitational wave backgrounds from large distance clock comparisons
Our spacetime is filled with gravitational wave backgrounds that constitute a
fluctuating environment created by astrophysical and cosmological sources.
Bounds on these backgrounds are obtained from cosmological and astrophysical
data but also by analysis of ranging and Doppler signals from distant
spacecraft. We propose here a new way to set bounds on those backgrounds by
performing clock comparisons between a ground clock and a remote spacecraft
equipped with an ultra-stable clock, rather than only ranging to an onboard
transponder. This technique can then be optimized as a function of the signal
to be measured and the dominant noise sources, leading to significant
improvements on present bounds in a promising frequency range where different
theoretical models are competing. We illustrate our approach using the SAGAS
project which aims to fly an ultra stable optical clock in the outer solar
system.Comment: 10 pages, 8 figures, minor amendment
Influence of electron correlations on ground-state properties of III-V semiconductors
Lattice constants and bulk moduli of eleven cubic III-V semiconductors are
calculated using an ab initio scheme. Correlation contributions of the valence
electrons, in particular, are determined using increments for localized bonds
and for pairs and triples of such bonds; individual increments, in turn, are
evaluated using the coupled cluster approach with single and double
excitations. Core-valence correlation is taken into account by means of a core
polarization potential. Combining the results at the correlated level with
corresponding Hartree-Fock data, we obtain lattice constants which agree with
experiment within an average error of -0.2%; bulk moduli are accurate to +4%.
We discuss in detail the influence of the various correlation contributions on
lattice constants and bulk moduli.Comment: 4 pages, Latex, no figures, Phys. Rev. B, accepte
Theory of Banana Liquid Crystal Phases and Phase Transitions
We study phases and phase transitions that can take place in the newly
discovered banana (bow-shaped or bent-core) liquid crystal molecules. We show
that to completely characterize phases exhibited by such bent-core molecules a
third-rank tensor order parameter is necessary in addition to the
vector and the nematic (second-rank) tensor order parameters. We present an
exhaustive list of possible liquid phases, characterizing them by their
space-symmetry group and order parameters, and catalog the universality classes
of the corresponding phase transitions that we expect to take place in such
bent-core molecular liquid crystals. In addition to the conventional
liquid-crystal phases such as the nematic phase, we predict the existence of
novel liquid phases, including the spontaneously chiral nematic
and chiral polar phases, the orientationally-ordered but
optically isotropic tetrahedratic phase, and a novel nematic phase
with symmetry that is neither uniaxial nor biaxial. Interestingly, the
Isotropic-Tetrahedratic transition is {\em continuous} in mean-field theory,
but is likely driven first-order by thermal fluctuations. We conclude with a
discussion of smectic analogs of these phases and their experimental
signatures.Comment: 28 pgs. RevTex, 32 eps figures, submitted to Phys. Rev.
Synthesis of amides from acid chlorides and amines in the bio-based solvent Cyreneâ„¢
Cyreneâ„¢ as a bio-alternative dipolar aprotic solvent: a waste minimizing and molar efficient protocol for the synthesis of amides from acid chlorides and primary amines in the bio-available solvent Cyreneâ„¢ is disclosed. This protocol removed the use of toxic solvents, such as dimethylformamide and dichloromethane. A simple aqueous work-up procedure for the removal of the high boiling solvent Cyreneâ„¢ resulted in up to a 55-fold increase in molar efficiency (Mol E.%) versus standard operating procedures. In order to rapidly compare the molar efficiency of this process against other methodologies an Excel based Mol. E% calculator was developed that automates many of the calculations. An investigation into the hydration of Cyreneâ„¢ found that it readily hydrates to form a geminal diol in the presence of water and that this process is exothermic
Efficacy of Online Training for Improving Camp Staff Competency
Preparing competent staff is a critical issue within the camp community. This quasi-experimental study examined the effectiveness of an online course for improving staff competency in camp healthcare practices among college-aged camp staff and a comparison group (N = 55). We hypothesized that working in camp would increase competency test scores due to opportunities for staff to experientially apply knowledge learned online. Hierarchical linear modeling was used to analyse the cross-level effects of a between-individuals factor (assignment to experimental or comparison group) and within-individual effects of time (pre-test, post-test #1, and post-test #2) on online course test scores. At post-test #2, the difference in average test scores between groups was ~30 points, with the treatment group scoring lower on average than the comparison group. Factors that may have influenced these findings are explored, including fatigue and the limited durability of online learning. Recommendations for research and practice are discussed
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