34,399 research outputs found
Optimal paths on the road network as directed polymers
We analyze the statistics of the shortest and fastest paths on the road
network between randomly sampled end points. To a good approximation, these
optimal paths are found to be directed in that their lengths (at large scales)
are linearly proportional to the absolute distance between them. This motivates
comparisons to universal features of directed polymers in random media. There
are similarities in scalings of fluctuations in length/time and transverse
wanderings, but also important distinctions in the scaling exponents, likely
due to long-range correlations in geographic and man-made features. At short
scales the optimal paths are not directed due to circuitous excursions governed
by a fat-tailed (power-law) probability distribution.Comment: 5 pages, 7 figure
An evaluation of subjective experiences, effects and overall satisfaction with clozapine treatment in a UK forensic service
Objectives: Patients prescribed clozapine were surveyed to assess (a) the effects, both positive and adverse, and overall satisfaction with clozapine in comparison to previously prescribed antipsychotics and (b) the relative significance of effects experienced, both positive and adverse, in terms of impact on subjective well-being.
Methods: A total of 56 male patients prescribed clozapine at a forensic psychiatric hospital were surveyed using a 27-item questionnaire. All patients had been prescribed clozapine for a minimum of 3 months. Respondents were asked to rate effects and satisfaction with clozapine treatment in comparison with previously prescribed antipsychotic medication on a five-point scale. Respondents were also asked to rate effects experienced with clozapine treatment in terms of impact on subjective well-being on a five-point scale.
Results: A total of 89% of respondents reported greater satisfaction with clozapine than with previously prescribed antipsychotic medication. A majority of patients reported positive effects in terms of an improvement in their quality of life (68%) and social abilities (52%) with clozapine in comparison with previously prescribed antipsychotics. Nocturnal hypersalivation (84%) and weight gain (57%) were the most common adverse effects. Hedonic responses were assessed for each effect in order to determine the associated subjective experiences. The most positive hedonic responses were for quality of life, mood and alertness. In terms of adverse impact on subjective well-being, nocturnal hypersalivation ranked highest.
Conclusions: Patients in a UK forensic sample are largely satisfied with clozapine treatment. The subjective effects of clozapine treatment should be taken into account by clinicians when assessing response. This may provide an opportunity to highlight the positive changes and prioritize management of the most undesirable adverse effects, which is likely to promote compliance and improve longer term treatment outcomes
Local Commutativity and Causality in Interacting PP-wave String Field Theory
In this paper, we extend our previous study of causality and local
commutativity of string fields in the pp-wave lightcone string field theory to
include interaction. Contrary to the flat space case result of Lowe,
Polchinski, Susskind, Thorlacius and Uglum, we found that the pp-wave
interaction does not affect the local commutativity condition. Our results show
that the pp-wave lightcone string field theory is not continuously connected
with the flat space one. We also discuss the relation between the condition of
local commutativity and causality. While the two notions are closely related in
a point particle theory, their relation is less clear in string theory. We
suggest that string local commutativity may be relevant for an operational
defintion of causality using strings as probes.Comment: Latex, JHEP3.cls, 18 pages, no figures. v2: add comments about the
UV-IR mixing effect displayed in our result. version to appear in JHE
Structure of CdTe/ZnTe superlattices
The structure of CdTe/ZnTe superlattices has been analyzed through θ/2θ x‐ray diffraction, photoluminescence, and in situ reflection high‐energy electron diffraction (RHEED) measurements. Samples are found to break away from Cd_(x)Zn_(1−x)Te buffer layers as a consequence of the 6% lattice mismatch in this system. However, defect densities in these superlattices are seen to drop dramatically away from the buffer layer interface, accounting for the intense photoluminescence and high‐average strain fields seen in each of our samples. Observed variations in residual strains suggest that growth conditions play a role in forming misfit defects. This could explain discrepancies with calculated values of critical thickness based on models which neglect growth conditions. Photoluminescence spectra reveal that layer‐to‐layer growth proceeded with single monolayer uniformity, suggesting highly reproducible growth. Our results give hope for relatively defect‐free Cd_(x)Zn_(1−x)Te/Cd_(y)Zn_(1−y)Te superlattices with the potential for applications to optoelectronics offered by intense visible light emitters
All-optical switching in a two-channel waveguide with cubic-quintic nonlinearity
We consider dynamics of spatial beams in a dual-channel waveguide with
competing cubic and quintic (CQ) nonlinearities. Gradually increasing the power
in the input channel, we identify four different regimes of the pulses coupling
into the cross channel, which alternate three times between full pass and full
stop, thus suggesting three realizations of switching between the channels. As
in the case of the Kerr (solely cubic) nonlinearity, the first two regimes are
the linear one, and one dominated by the self-focusing nonlinearity, with the
beam which, respectively, periodically couples between the channels, or stays
in the input channel. Further increase of the power reveals two novel
transmission regimes, one characterized by balance between the competing
nonlinearities, which again allows full coupling between the channels, and a
final regime dominated by the self-defocusing quintic nonlinearity. In the
latter case, the situation resembles that known for a self-repulsive
Bose-Einstein condensate trapped in a double-well potential, which is
characterized by strong symmetry breaking; accordingly, the beam again abides
in the input channel, contrary to an intuitive expectation that the
self-defocusing nonlinearity would push it into the cross channel. The
numerical results are qualitatively explained by a simple analytical model
based on the variational approximation.Comment: Journal of Physics B (in press
Designing a Biosensor Using a Photonic Quasi-Crystal Fiber with Fan-shaped Analyte Channel
Postprin
A natural study of the efficacy of replacement medications for the treatment of clozapine-induced hypersalivation
Magnetic Helicity in Sphaleron Debris
We develop an analytical technique to evaluate the magnetic helicity in the
debris from sphaleron decay. We show that baryon number production leads to
left-handed magnetic fields, and that the magnetic helicity is conserved at
late times. Our analysis explicitly demonstrates the connection between
sphaleron-mediated cosmic baryogenesis and cosmic magnetogenesis.Comment: 9 pages, 1 figure. v2: Minor revisions; matches published version in
Physical Review
DLCQ String Spectrum from SYM Theory
We study non planar corrections to the spectrum of operators in the
supersymmetric Yang Mills theory which are dual to string
states in the maximally supersymmetric pp-wave background with a {\em compact}
light-cone direction. The existence of a positive definite discrete light-cone
momentum greatly simplifies the operator mixing problem. We give some examples
where the contribution of all orders in non-planar diagrams can be found
analytically. On the string theory side this corresponds to finding the
spectrum of a string state to all orders in string loop corrections.Comment: 35 pages, no figure
Raman scattering study of electron-doped PrCaFeAs superconductors
Temperature-dependent polarized Raman spectra of electron-doped
superconducting PrCaFeAs () single crystals
are reported. All four allowed by symmetry even-parity phonons are identified.
Phonon mode of B symmetry at 222 cm, which is associated with the
c-axis motion of Fe ions, is found to exhibit an anomalous frequency hardening
at low temperatures, that signals non-vanishing electron-phonon coupling in the
superconducting state and implies that the superconducting gap magnitude
meV.Comment: 4 pages, 3 figure
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