3,167 research outputs found
Dilated Floor Functions That Commute
We determine all pairs of real numbers such that the
dilated floor functions and
commute under composition, i.e., such that holds for all
real .Comment: 6 pages, to appear in Amer. Math. Monthl
Field Quantization in 5D Space-Time with Z-parity and Position/Momentum Propagator
Field quantization in 5D flat and warped space-times with Z-parity is
comparatively examined. We carefully and closely derive 5D
position/momentum(P/M) propagators. Their characteristic behaviours depend on
the 4D (real world) momentum in relation to the boundary parameter () and
the bulk curvature (\om). They also depend on whether the 4D momentum is
space-like or time-like. Their behaviours are graphically presented and the
Z symmetry, the "brane" formation and the singularities are examined. It is
shown that the use of absolute functions is important for properly treating the
singular behaviour. The extra coordinate appears as a {\it directed} one like
the temperature. The problem, which is an important consistency
check of the bulk-boundary system, is solved {\it without} the use of
KK-expansion. The relation between P/M propagator (a closed expression which
takes into account {\it all} KK-modes) and the KK-expansion-series propagator
is clarified. In this process of comparison, two views on the extra space
naturally come up: orbifold picture and interval (boundary) picture.
Sturm-Liouville expansion (a generalized Fourier expansion) is essential there.
Both 5D flat and warped quantum systems are formulated by the Dirac's bra and
ket vector formalism, which shows the warped model can be regarded as a {\it
deformation} of the flat one with the {\it deformation parameter} \om. We
examine the meaning of the position-dependent cut-off proposed by
Randall-Schwartz.Comment: 44 figures, 22(fig.)+41 pages, to be published in Phys.Rev.D, Fig.4
is improve
Low-frequency local field potentials and spikes in primary visual cortex convey independent visual information
Local field potentials (LFPs) reflect subthreshold integrative processes that complement spike train measures. However, little is yet known about the differences between how LFPs and spikes encode rich naturalistic sensory stimuli. We addressed this question by recording LFPs and spikes from the primary visual cortex of anesthetized macaques while presenting a color movie.Wethen determined
how the power of LFPs and spikes at different frequencies represents the visual features in the movie.Wefound that the most informative LFP frequency ranges were 1– 8 and 60 –100 Hz. LFPs in the range of 12– 40 Hz carried little information about the stimulus, and may primarily reflect neuromodulatory inputs. Spike power was informative only at frequencies <12 Hz. We further quantified “signal
correlations” (correlations in the trial-averaged power response to different stimuli) and “noise correlations” (trial-by-trial correlations in the fluctuations around the average) of LFPs and spikes recorded from the same electrode. We found positive signal correlation between high-gamma LFPs (60 –100 Hz) and spikes, as well as strong positive signal correlation within high-gamma LFPs, suggesting that high-gamma LFPs and spikes are generated within the same network. LFPs<24 Hz shared strong positive noise correlations, indicating that they are influenced by a common source, such as a diffuse neuromodulatory input. LFPs<40 Hz showed very little signal and noise correlations with LFPs>40Hzand with spikes, suggesting that low-frequency LFPs reflect neural processes that in natural conditions are fully decoupled from those giving rise to spikes and to high-gamma LFPs
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Complete recovery from anxiety disorders following Cognitive Behavioural Therapy in children and adolescents: a meta analysis
Cognitive Behavior Therapy (CBT) is a well-established treatment for childhood anxiety disorders. Meta-analyses have concluded that approximately 60% of children recover following treatment, however these include studies using a broad range of diagnostic indices to assess outcomes including whether children are free of the one anxiety disorder that causes most interference (i.e. the primary anxiety disorder) or whether children are free of all anxiety disorders. We conducted a meta-analysis to establish the efficacy of CBT in terms of absence of all anxiety disorders. Where available we compared this rate to outcomes based on absence of primary disorder. Of 56 published randomized controlled trials, 19 provided data on recovery from all anxiety disorders (n = 635 CBT, n = 450 control participants). There was significant heterogeneity across those studies with available data and full recovery rates varied from 47.6 to 66.4% among children without autistic spectrum conditions (ASC) and 12.2 to 36.7% for children with ASC following treatment, compared to up to 20.6% and 21.3% recovery in waitlist and active treatment comparisons. The lack of consistency in diagnostic outcomes highlights the urgent need for consensus on reporting in future RCTs of childhood anxiety disorders for the meaningful synthesis of data going forwards
Spatio-Temporal Urban Land Use/Cover Change Analysis in a Hill Station: The Case of Baguio City, Philippines
AbstractThis study explores the spatial and temporal characteristics of land use/cover (LUC) changes in Baguio city, the only American hill station in Asia and the summer capital of the Philippines. Remote sensing (RS) satellite images were used to develop the 1988, 1998, and 2009 LUC maps of the city in a Geographic Information Systems (GIS) platform. Results reveal that the city has undergone a major physical landscape transformation for the last 21 years as indicated by a rapid built-up area expansion and substantial changes in its other land uses/covers. This study also analyzes the spatial pattern of urban growth in Baguio city. Furthermore, it presents insights in planning for the future sustainable urbanization of this highly valued city
Physics at e^- e^-: a Case for Multi-channel Studies
I argue that it would be crucial to have as many channels as possible to
understand the physics of electroweak symmetry breaking (EWSB) in
next-generation collider experiments. A historic example of the parity
violation and the interaction is used to make this point. An e^- e^-
option offers us a new channel in this respect. The usefulness of this channel
is exemplified for the case of supersymmetry and of the strongly coupled EWSB
sector.Comment: 8 pages, 3 figures, uses psfig, to appear in the proceedings of the
the Second International Workshop on Electron-Electron Interactions at TeV
Energies, references correcte
High-Energy Neutrino Signatures of Dark Matter Decaying into Leptons
Decaying dark matter has previously been proposed as a possible explanation
for the excess high energy cosmic ray electrons and positrons seen by PAMELA
and the Fermi Gamma-Ray Space Telescope (FGST). To accommodate these signals
however, the decays must be predominantly leptonic, to muons or taus, and
therefore produce neutrinos, potentially detectable with the IceCube neutrino
observatory. We find that, with five years of data, IceCube (supplemented by
DeepCore) will be able to significantly constrain the relevant parameter space
of decaying dark matter, and may even be capable of discovering dark matter
decaying in the halo of the Milky Way.Comment: 4 pages, 1 figur
Discriminating spin through quantum interference
Many of the proposed solutions to the hierarchy and naturalness problems
postulate new `partner' fields to the standard model particles. Determining the
spins of these new particles will be critical in distinguishing among the
various possible SM extensions, yet proposed methods rely on the underlying
models. We propose a new model-independent method for spin measurements which
takes advantage of quantum interference among helicity states. We demonstrate
that this method will be able to discriminate scalar particles from higher spin
states at the ILC, and discuss application to higher spins and possible uses at
the LHC.Comment: 11 pages, 11 figure
Transport properties of a quantum wire: the role of extended time-dependent impurities
We study the transport properties of a quantum wire, described by the
Tomonaga-Luttinger model, in the presence of a backscattering potential
provided by several extended time-dependent impurities (barriers). Employing
the B\" uttiker-Landauer approach, we first consider the scattering of
noninteracting electrons () by a rectangular-like barrier and find an
exact solution for the backscattering current, as well as a perturbative
solution for a weak static potential with an arbitrary shape. We then include
electron-electron interactions and use the Keldysh formalism combined with the
bosonization technique to study oscillating extended barriers. We show that the
backscattering current off time-dependent impurities can be expressed in terms
of the current for the corresponding static barrier. Then we determine the
backscattering current for a static extended potential, which, in the limit of
noninteracting electrons (), coincides with the result obtained using the
B\" uttiker-Landauer formalism. In particular, we find that the conductance can
be increased beyond its quantized value in the whole range of repulsive
interactions already in the case of a single oscillating extended
impurity, in contrast %contrary to the case of a point-like impurity, where
this phenomenon occurs only for .Comment: 9 pages, 5 figure
Cosmological Higgs fields
We present a time-dependent solution to the coupled Einstein-Higgs equations
for general Higgs-type potentials in the context of flat FRW cosmological
models. Possible implications are discussed.Comment: 5 pages, no figures. Version to be published in Phys. Rev. Lett.
Changes: references and citations added; introduction partly modified;
expanded discussion of relations between parameters in the Higgs potentia
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