13,782 research outputs found
Global gyrokinetic simulations of intrinsic rotation in ASDEX Upgrade Ohmic L-mode plasmas
Non-linear, radially global, turbulence simulations of ASDEX Upgrade (AUG)
plasmas are performed and the nonlinear generated intrinsic flow shows
agreement with the intrinsic flow gradients measured in the core of Ohmic
L-mode plasmas at nominal parameters. Simulations utilising the kinetic
electron model show hollow intrinsic flow profiles as seen in a predominant
number of experiments performed at similar plasma parameters. In addition,
significantly larger flow gradients are seen than in a previous flux-tube
analysis (Hornsby et al {\it Nucl. Fusion} (2017)). Adiabatic electron model
simulations can show a flow profile with opposing sign in the gradient with
respect to a kinetic electron simulation, implying a reversal in the sign of
the residual stress due to kinetic electrons. The shaping of the intrinsic flow
is strongly determined by the density gradient profile. The sensitivity of the
residual stress to variations in density profile curvature is calculated and
seen to be significantly stronger than to neoclassical flows (Hornsby et al
{\it Nucl. Fusion} (2017)). This variation is strong enough on its own to
explain the large variations in the intrinsic flow gradients seen in some AUG
experiments. Analysis of the symmetry breaking properties of the turbulence
shows that profile shearing is the dominant mechanism in producing a finite
parallel wave-number, with turbulence gradient effects contributing a smaller
portion of the parallel wave-vector
Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. V. A New Size-Luminosity Scaling Relation for the Broad-Line Region
This paper reports results of the third-year campaign of monitoring
super-Eddington accreting massive black holes (SEAMBHs) in active galactic
nuclei (AGNs) between 2014-2015. Ten new targets were selected from quasar
sample of Sloan Digital Sky Survey (SDSS), which are generally more luminous
than the SEAMBH candidates in last two years. H lags () in five of the 10 quasars have been successfully measured in this
monitoring season. We find that the lags are generally shorter, by large
factors, than those of objects with same optical luminosity, in light of the
well-known relation. The five quasars have
dimensionless accretion rates of . Combining
measurements of the previous SEAMBHs, we find that the reduction of H
lags tightly depends on accretion rates, , where
is the H lag from the normal relation.
Fitting 63 mapped AGNs, we present a new scaling relation for the broad-line
region: ,
where is 5100 \AA\ continuum
luminosity, and coefficients of lt-d,
, and
. This relation is applicable to
AGNs over a wide range of accretion rates, from to .
Implications of this new relation are briefly discussed.Comment: 15 pages, 9 figures, 5 table, accepted for publication in The
Astrophysical Journa
Non-intrusive Head Movement Analysis of Videotaped Seizures of Epileptic Origin
Abstract — In this work we propose a non-intrusive video analytic system for patient’s body parts movement analysis in Epilepsy Monitoring Unit. The system utilizes skin color modeling, head/face pose template matching and face detection to analyze and quantify the head movements. Epileptic patients’ heads are analyzed holistically to infer seizure and normal random movements. The patient does not require to wear any special clothing, markers or sensors, hence it is totally nonintrusive. The user initializes the person-specific skin color and selects few face/head poses in the initial few frames. The system then tracks the head/face and extracts spatio-temporal features. Support vector machines are then used on these features to classify seizure-like movements from normal random movements. Experiments are performed on numerous long hour video sequences captured in an Epilepsy Monitoring Unit at a local hospital. The results demonstrate the feasibility of the proposed system in pediatric epilepsy monitoring and seizure detection. I
Les temps de la consultation du comité d’entreprise
The DD4HEP detector description toolkit offers a flexible and easy-to-use solution for the consistent and complete description of particle physics detectors in a single system. The sub-component DDREC provides a dedicated interface to the detector geometry as needed for event reconstruction. With DDREC there is no need to define an additional, separate reconstruction geometry as is often done in HEP, but one can transparently extend the existing detailed simulation model to be also used for the reconstruction. Based on the extension mechanism of DD4HEP, DDREC allows one to attach user defined data structures to detector elements at all levels of the geometry hierarchy. These data structures define a high level view onto the detectors describing their physical properties, such as measurement layers, point resolutions, and cell sizes. For the purpose of charged particle track reconstruction, dedicated surface objects can be attached to every volume in the detector geometry. These surfaces provide the measurement directions, local-to-global coordinate transformations, and material properties. The material properties, essential for the correct treatment of multiple scattering and energy loss effects in charged particle reconstruction, are automatically averaged from the detailed geometry model along the normal of the surface. Additionally, a generic interface allows the user to query material properties at any given point or between any two points in the detector's world volume. In this paper we will present DDREC and how it is used together with the linear collider tracking software and the particle-flow package PANDORAPFA for full event reconstruction of the ILC detector concepts ILD and SiD, and of CLICdp. This flexible tool chain is also well suited for other future accelerator projects such as FCC and CEPC
JLab Measurement of the He Charge Form Factor at Large Momentum Transfers
The charge form factor of ^4He has been extracted in the range 29 fm
fm from elastic electron scattering, detecting He
nuclei and electrons in coincidence with the High Resolution Spectrometers of
the Hall A Facility of Jefferson Lab. The results are in qualitative agreement
with realistic meson-nucleon theoretical calculations. The data have uncovered
a second diffraction minimum, which was predicted in the range of this
experiment, and rule out conclusively long-standing predictions of dimensional
scaling of high-energy amplitudes using quark counting.Comment: 4 pages, 2 figure
Measurement of the Target-Normal Single-Spin Asymmetry in Quasi-Elastic Scattering from the Reaction He
We report the first measurement of the target single-spin asymmetry, ,
in quasi-elastic scattering from the inclusive reaction
He on a He gas target polarized normal to the
lepton scattering plane. Assuming time-reversal invariance, this asymmetry is
strictly zero for one-photon exchange. A non-zero can arise from the
interference between the one- and two-photon exchange processes which is
sensitive to the details of the sub-structure of the nucleon. An experiment
recently completed at Jefferson Lab yielded asymmetries with high statistical
precision at 0.13, 0.46 and 0.97 GeV. These measurements
demonstrate, for the first time, that the He asymmetry is clearly non-zero
and negative with a statistical significance of (8-10). Using measured
proton-to-He cross-section ratios and the effective polarization
approximation, neutron asymmetries of (1-3)% were obtained. The neutron
asymmetry at high is related to moments of the Generalized Parton
Distributions (GPDs). Our measured neutron asymmetry at GeV
agrees well with a prediction based on two-photon exchange using a GPD model
and thus provides a new, independent constraint on these distributions
A Unified Approach to the Classical Statistical Analysis of Small Signals
We give a classical confidence belt construction which unifies the treatment
of upper confidence limits for null results and two-sided confidence intervals
for non-null results. The unified treatment solves a problem (apparently not
previously recognized) that the choice of upper limit or two-sided intervals
leads to intervals which are not confidence intervals if the choice is based on
the data. We apply the construction to two related problems which have recently
been a battle-ground between classical and Bayesian statistics: Poisson
processes with background, and Gaussian errors with a bounded physical region.
In contrast with the usual classical construction for upper limits, our
construction avoids unphysical confidence intervals. In contrast with some
popular Bayesian intervals, our intervals eliminate conservatism (frequentist
coverage greater than the stated confidence) in the Gaussian case and reduce it
to a level dictated by discreteness in the Poisson case. We generalize the
method in order to apply it to analysis of experiments searching for neutrino
oscillations. We show that this technique both gives correct coverage and is
powerful, while other classical techniques that have been used by neutrino
oscillation search experiments fail one or both of these criteria.Comment: 40 pages, 15 figures. Changes 15-Dec-99 to agree more closely with
published version. A few small changes, plus the two substantive changes we
made in proof back in 1998: 1) The definition of "sensitivity" in Sec. V(C).
It was inconsistent with our actual definition in Sec. VI. 2) "Note added in
proof" at end of the Conclusio
Measurement of pretzelosity asymmetry of charged pion production in Semi-Inclusive Deep Inelastic Scattering on a polarized He target
An experiment to measure single-spin asymmetries in semi-inclusive production
of charged pions in deep-inelastic scattering on a transversely polarized
He target was performed at Jefferson Lab in the kinematic region of
and . The pretzelosity asymmetries on
He, which can be expressed as the convolution of the
transverse momentum dependent distribution functions and the Collins
fragmentation functions in the leading order, were measured for the first time.
Using the effective polarization approximation, we extracted the corresponding
neutron asymmetries from the measured He asymmetries and cross-section
ratios between the proton and He. Our results show that for both
on He and on the neutron the pretzelosity asymmetries are
consistent with zero within experimental uncertainties.Comment: 6 pages, 3 figures; enlarged the legends in Fig.3; added 3 citation
Observation of decays into vector meson pairs , , and
Decays of to vector meson pairs , and
are observed for the first time using
\psip events accumulated at the BESIII detector at the BEPCII
collider. The branching fractions are measured to be , , and , for , , and ,
respectively. The observation of decays into a pair of vector
mesons , and indicates that the hadron
helicity selection rule is significantly violated in decays. In
addition, the measurement of gives the rate of doubly
OZI-suppressed decay. Branching fractions for and
decays into other vector meson pairs are also measured with improved precision.Comment: 4 pages, 2 figure
Single Spin Asymmetries in Charged Kaon Production from Semi-Inclusive Deep Inelastic Scattering on a Transversely Polarized Target
We report the first measurement of target single spin asymmetries of charged
kaons produced in semi-inclusive deep inelastic scattering of electrons off a
transversely polarized target. Both the Collins and Sivers
moments, which are related to the nucleon transversity and Sivers
distributions, respectively, are extracted over the kinematic range of
0.10.4 for and production. While the Collins and
Sivers moments for are consistent with zero within the experimental
uncertainties, both moments for favor negative values. The Sivers
moments are compared to the theoretical prediction from a phenomenological fit
to the world data. While the Sivers moments are consistent with the
prediction, the results differ from the prediction at the 2-sigma
level.Comment: 6 pages, 3 figure
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