25,479 research outputs found
Psychodynamic therapy: a poorly defined concept with questionable evidence
R34 MH086668 - NIMH NIH HHS; R01 AT007257 - NCCIH NIH HHS; R21 MH101567 - NIMH NIH HHS; R34 MH099311 - NIMH NIH HHS; R21 MH102646 - NIMH NIH HHS; K23 MH100259 - NIMH NIH HHS; R01 MH099021 - NIMH NIH HH
The probability that and commute in a compact group
We show that a compact group has finite conjugacy classes, i.e., is an
FC-group if and only if its center is open if and only if its commutator
subgroup is finite. Let denote the Haar measure of the set of all
pairs in for which ; this, formally, is the
probability that two randomly picked elements commute. We prove that is
always rational and that it is positive if and only if is an extension of
an FC-group by a finite group. This entails that is abelian by finite. The
proofs involve measure theory, transformation groups, Lie theory of arbitrary
compact groups, and representation theory of compact groups. Examples and
references to the history of the discussion are given at the end of the paper.Comment: 17 pages; we have cut some points ; to appear in Math. Proc.
Cambridge Phil. So
Mindfulness-based interventions for anxiety and depression
Published in final edited form as: Psychiatr Clin North Am. 2017 December ; 40(4): 739–749. doi:10.1016/j.psc.2017.08.008.This article reviews the ways in which mindfulness practices have contributed to cognitive and behavioral treatments for depression and anxiety. Research on mindfulness-based interventions (MBIs) has increased rapidly in the past decade. The most common include mindfulness-based stress reduction and mindfulness-based cognitive therapy. MBIs are effective in reducing anxiety and depression symptom severity in a range of individuals. MBIs consistently outperform non-evidence-based treatments and active control conditions, such as health education, relaxation training, and supportive psychotherapy. MBIs also perform comparably with cognitive behavior therapy (CBT). The treatment principles of MBIs for anxiety and depression are compatible with standard CBT.R01 AT007257 - NCCIH NIH HH
Optimal multi-photon phase sensing with a single interference fringe
Quantum entanglement can help to increase the precision of optical phase
measurements beyond the shot noise limit (SNL) to the ultimate Heisenberg
limit. However, the N-photon parity measurements required to achieve this
optimal sensitivity are extremely difficult to realize with current photon
detection technologies, requiring high-fidelity resolution of N+1 different
photon distributions between the output ports. Recent experimental
demonstrations of precision beyond the SNL have therefore used only one or two
photon-number detection patterns instead of parity measurements. Here we
investigate the achievable phase sensitivity of the simple and efficient single
interference fringe detection technique. We show that the maximally-entangled
"NOON" state does not achieve optimal phase sensitivity when N > 4, rather, we
show that the Holland-Burnett state is optimal. We experimentally demonstrate
this enhanced sensitivity using a single photon-counted fringe of the
six-photon Holland-Burnett state. Specifically, our single-fringe six-photon
measurement achieves a phase variance three times below the SNL.Comment: 7 pages, 4 figure
Vigorous atmospheric motion in the red supergiant star Antares
Red supergiant stars represent a late stage of the evolution of stars more
massive than about nine solar masses, in which they develop complex,
multi-component atmospheres. Bright spots have been detected in the atmosphere
of red supergiants using interferometric imaging. Above the photosphere of a
red supergiant, the molecular outer atmosphere extends up to about two stellar
radii. Furthermore, the hot chromosphere (5,000 to 8,000 kelvin) and cool gas
(less than 3,500 kelvin) of a red supergiant coexist at about three stellar
radii. The dynamics of such complex atmospheres has been probed by ultraviolet
and optical spectroscopy. The most direct approach, however, is to measure the
velocity of gas at each position over the image of stars as in observations of
the Sun. Here we report the mapping of the velocity field over the surface and
atmosphere of the nearby red supergiant Antares. The two-dimensional velocity
field map obtained from our near-infrared spectro-interferometric imaging
reveals vigorous upwelling and downdrafting motions of several huge gas clumps
at velocities ranging from about -20 to +20 kilometres per second in the
atmosphere, which extends out to about 1.7 stellar radii. Convection alone
cannot explain the observed turbulent motions and atmospheric extension,
suggesting that an unidentified process is operating in the extended
atmosphere.Comment: 27 pages, 8 figures, published in Natur
Cherenkov Telescope Array: The next-generation ground-based gamma-ray observatory
High energy gamma-ray astronomy is a newly emerging and very successful
branch of astronomy and astrophysics. Exciting results have been obtained by
the current generation Cherenkov telescope systems such as H.E.S.S., MAGIC,
VERITAS and CANGAROO. The H.E.S.S. survey of the galactic plane has revealed a
large number of sources and addresses issues such as the question about the
origin of cosmic rays. The detection of very high energy emission from
extragalactic sources at large distances has provided insights in the star
formation during the history of the universe and in the understanding of active
galactic nuclei. The development of the very large Cherenkov telescope array
system (CTA) with a sensitivity about an order of magnitude better than current
instruments and significantly improved sensitivity is under intense discussion.
This observatory will reveal an order of magnitude more sources and due to its
higher sensitivity and angular resolution it will be able to detect new classes
of objects and phenomena that have not been visible until now. A combination of
different telescope types will provide the sensitivity needed in different
energy ranges.Comment: 4 pages, 3 figures, to appear in the proceedings of the 30th
International Cosmic Ray Conference, Merida, July 200
Triggering of Imaging Air Cherenkov Telescopes: PMT trigger rates due to night-sky photons
Imaging air Cherenkov telescopes are usually triggered on a coincidence of
two or sometimes more pixels, with discriminator thresholds in excess of 20
photoelectrons applied for each pixel. These thresholds required to suppress
night-sky background are significantly higher than expected on the basis of a
Poisson distribution in the number of night-sky photoelectrons generated during
the characteristic signal integration time.
We studied noise trigger rates under controlled conditions using an
artificial background light source. Large tails in the PMT amplitude response
to single photoelectrons are identified as a dominant contribution to noise
triggers. The rate of such events is very sensitive to PMT operating
parameters.Comment: 19 pages, latex,epsf, 7 figures appended as uuencoded file, submitted
to Journal of Physics
New procedure for design of self-adaptive control systems
Adaptive control system compensates for changes in the dynamic characteristics of linear controlled elements. It is mechanized so that the actual input of each control approaches the ideal input
Quantum-state tomography for spin-l systems
We show that the density matrix of a spin-l system can be described entirely
in terms of the measurement statistics of projective spin measurements along a
minimum of 4l+1 different spin directions. It is thus possible to represent the
complete quantum statistics of any N-level system within the spherically
symmetric three dimensional space defined by the spin vector. An explicit
method for reconstructing the density matrix of a spin-1 system from the
measurement statistics of five non-orthogonal spin directions is presented and
the generalization to spin-l systems is discussed.Comment: 10 pages, including 2 tables, minor modifications in section II,
final version for publication in Phys. Rev.
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