5,150 research outputs found
Modeling heat transfer from quench protection heaters to superconducting cables in Nb3Sn magnets
We use a recently developed quench protection heater modeling tool for an
analysis of heater delays in superconducting high-field Nb3Sn accelerator
magnets. The results suggest that the calculated delays are consistent with
experimental data, and show how the heater delay depends on the main heater
design parameters.Comment: 8 pages, Contribution to WAMSDO 2013: Workshop on Accelerator Magnet,
Superconductor, Design and Optimization; 15 - 16 Jan 2013, CERN, Geneva,
Switzerlan
Massive Clumps in the NGC 6334 Star Forming Region
We report observations of dust continuum emission at 1.2 mm toward the star
forming region NGC 6334 made with the SEST SIMBA bolometer array. The
observations cover an area of square degrees with approximately
uniform noise. We detected 181 clumps spanning almost three orders of magnitude
in mass (3\Msun \Msun) and with sizes in the range 0.1--1.0 pc.
We find that the clump mass function is well fit with a power law
of the mass with exponent -0.6 (or equivalently ). The
derived exponent is similar to those obtained from molecular line emission
surveys and is significantly different from that of the stellar initial mass
function. We investigated changes in the mass spectrum by changing the
assumptions on the temperature distribution of the clumps and on the
contribution of free-free emission to the 1.2 mm emission, and found little
changes on the exponent. The Cumulative Mass Distribution Function is also
analyzed giving consistent results in a mass range excluding the high-mass end
where a power-law fit is no longer valid. The masses and sizes of the clumps
observed in NGC 6334 indicate that they are not direct progenitors of stars and
that the process of fragmentation determines the distribution of masses later
on or occurs at smaller spatial scales. The spatial distribution of the clumps
in NGC 6334 reveals clustering which is strikingly similar to that exhibited by
young stars in other star forming regions. A power law fit to the surface
density of companions gives .Comment: 16 pages, 11 figures, 4 tables. To appear in the Astrophysical
Journa
The unified protocol for transdiagnostic treatment of emotional disorders compared with diagnosis-specific protocols for anxiety disorders a randomized clinical trial
IMPORTANCE: Transdiagnostic interventions have been developed to address barriers to the dissemination of evidence-based psychological treatments, but only a few preliminary studies have compared these approaches with existing evidence-based psychological treatments.
OBJECTIVE: To determine whether the Unified Protocol for Transdiagnostic Treatment of Emotional Disorders (UP) is at least as efficacious as single-disorder protocols (SDPs) in the treatment of anxiety disorders.
DESIGN, SETTING, AND PARTICIPANTS: From June 23, 2011, to March 5, 2015, a total of 223 patients at an outpatient treatment center with a principal diagnosis of panic disorder with or without agoraphobia, generalized anxiety disorder, obsessive-compulsive disorder, or social anxiety disorder were randomly assigned by principal diagnosis to the UP, an SDP, or a waitlist control condition. Patients received up to 16 sessions of the UP or an SDP for 16 to 21 weeks. Outcomes were assessed at baseline, after treatment, and at 6-month follow-up. Analysis in this equivalence trial was based on intention to treat.
INTERVENTIONS: The UP or SDPs.
MAIN OUTCOMES AND MEASURES: Blinded evaluations of principal diagnosis clinical severity rating were used to evaluate an a priori hypothesis of equivalence between the UP and SDPs.
RESULTS: Among the 223 patients (124 women and 99 men; mean [SD] age, 31.1 [11.0] years), 88 were randomized to receive the UP, 91 to receive an SDP, and 44 to the waitlist control condition. Patients were more likely to complete treatment with the UP than with SDPs (odds ratio, 3.11; 95% CI, 1.44-6.74). Both the UP (Cohen d, â0.93; 95% CI, â1.29 to â0.57) and SDPs (Cohen d, â1.08; 95% CI, â1.43 to â0.73) were superior to the waitlist control condition at acute outcome. Reductions in clinical severity rating from baseline to the end of treatment (ÎČ, 0.25; 95% CI, â0.26 to 0.75) and from baseline to the 6-month follow-up (ÎČ, 0.16; 95% CI, â0.39 to 0.70) indicated statistical equivalence between the UP and SDPs.
CONCLUSIONS AND RELEVANCE: The UP produces symptom reduction equivalent to criterion standard evidence-based psychological treatments for anxiety disorders with less attrition. Thus, it may be possible to use 1 protocol instead of multiple SDPs to more efficiently treat the most commonly occurring anxiety and depressive disorders.This study was funded by grant R01 MH090053 from the National Institute of Mental Health. (R01 MH090053 - National Institute of Mental Health)First author draf
Towards a new generation axion helioscope
We study the feasibility of a new generation axion helioscope, the most
ambitious and promising detector of solar axions to date. We show that large
improvements in magnetic field volume, x-ray focusing optics and detector
backgrounds are possible beyond those achieved in the CERN Axion Solar
Telescope (CAST). For hadronic models, a sensitivity to the axion-photon
coupling of \gagamma\gtrsim {\rm few} \times 10^{-12} GeV is
conceivable, 1--1.5 orders of magnitude beyond the CAST sensitivity. If axions
also couple to electrons, the Sun produces a larger flux for the same value of
the Peccei-Quinn scale, allowing one to probe a broader class of models. Except
for the axion dark matter searches, this experiment will be the most sensitive
axion search ever, reaching or surpassing the stringent bounds from SN1987A and
possibly testing the axion interpretation of anomalous white-dwarf cooling that
predicts of a few meV. Beyond axions, this new instrument will probe
entirely unexplored ranges of parameters for a large variety of axion-like
particles (ALPs) and other novel excitations at the low-energy frontier of
elementary particle physics.Comment: 37 pages, 11 figures, accepted for publication in JCA
Development of light and highly radiation transparent cryostats for FCC detector magnets:First analyses of insulation materials
For both versions of the Future Circular Collider, the electron-positron FCC ee, requiring a 2 T/4 m bore solenoid for particles spectrometry, and the hadron-hadron FCC hh, CERN is developing an innovative design for the detector solenoids, to enable their positioning inside the calorimeters directly surrounding the inner tracker. For this to happen, the cryostat design has to be optimized to achieve minimum radiation length. The novel design consists of a sandwich of thin inner and outer metallic shells for vacuum tightness, supported by an insulating material with sufficient mechanical resistance paired with lowest thermal conductivity, like Cryogel, a flexible aerogel structure (density 0.16 g/cm), or glass spheres (e.g. type K1 manufactured by 3M, with 65 ÎŒm diameter and density of 0.125 g/cm). These materials would allow constructing a 4 m bore, 6 m long cryostat with a 250 mm total thickness, a heat load less than 400 W on the cold mass and 10 kW on the thermal shield. In this paper, design options are discussed and methods for qualifying the materials presented
Design and development of the ATLAS central solenoid magnet
The ATLAS central solenoid magnet is being constructed to provide a magnetic field of 2 T in the central tracking part of the ATLAS detector. As a key technology for a solenoid coil as thin as possible, a high-strength aluminum stabilized superconductor has been developed, achieving a yield strength of >100 MPa at 4.2 K. This paper describes the status of the design and development of the solenoid magnet. (14 refs)
A general scaling relation for the critical current density in Nb3Sn
We review the scaling relations for the critical current density (Jc) in
Nb3Sn wires and include recent findings on the variation of the upper critical
field (Hc2) with temperature (T) and A15 composition. We highlight deficiencies
in the Summers/Ekin relations, which are not able to account for the correct
Jc(T) dependence. Available Jc(H) results indicate that the magnetic field
dependence for all wires can be described with Kramer's flux shear model, if
non-linearities in Kramer plots are attributed to A15 inhomogeneities. The
strain (eps) dependence is introduced through a temperature and strain
dependent Hc2*(T,eps) and Ginzburg- Landau parameter kappa1(T,eps) and a strain
dependent critical temperature Tc(eps). This is more consistent than the usual
Ekin unification, which uses two separate and different dependencies on Hc2*(T)
and Hc2*(eps). Using a correct temperature dependence and accounting for the
A15 inhomogeneities leads to a remarkable simple relation for Jc(H,T,eps).
Finally, a new relation for s(eps) is proposed, based on the first, second and
third strain invariants.Comment: Accepted Topical Review for Superconductor, Science and Technolog
The International Axion Observatory (IAXO)
The International Axion Observatory (IAXO) is a new generation axion
helioscope aiming at a sensitivity to the axion-photon coupling of a few
10 GeV, i.e. 1 - 1.5 orders of magnitude beyond the one currently
achieved by CAST. The project relies on improvements in magnetic field volume
together with extensive use of x-ray focusing optics and low background
detectors, innovations already successfully tested in CAST. Additional physics
cases of IAXO could include the detection of electron-coupled axions invoked to
solve the white dwarfs anomaly, relic axions, and a large variety of more
generic axion-like particles (ALPs) and other novel excitations at the
low-energy frontier of elementary particle physics. This contribution is a
summary of our paper [1] to which we refer for further details.Comment: 4 pages, 2 figures. To appear in the proceedings of the 7th Patras
Workshop on Axions, WIMPs and WISPs, Mykonos, Greece, 201
Mechanisms and implications of gamma oscillation plasticity
A recent study by Hadler and colleagues uncovered a novel form of plasticity of gamma oscillations in an ex vivo hippocampal slice preparation which they term 'gamma potentiation'. We discuss the potential cellular mechanisms of this form of plasticity and its functional and translational implications
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