3,549 research outputs found
Power-Law Statistics Of Driven Reconnection In The Magnetically Closed Corona
Numerous observations have revealed that power-law distributions are
ubiquitous in energetic solar processes. Hard X-rays, soft X-rays, extreme
ultraviolet radiation, and radio waves all display power-law frequency
distributions. Since magnetic reconnection is the driving mechanism for many
energetic solar phenomena, it is likely that reconnection events themselves
display such power-law distributions. In this work, we perform numerical
simulations of the solar corona driven by simple convective motions at the
photospheric level. Using temperature changes, current distributions, and
Poynting fluxes as proxies for heating, we demonstrate that energetic events
occurring in our simulation display power-law frequency distributions, with
slopes in good agreement with observations. We suggest that the
braiding-associated reconnection in the corona can be understood in terms of a
self-organized criticality model driven by convective rotational motions
similar to those observed at the photosphere.Comment: Accepted by Ap
Single shot parameter estimation via continuous quantum measurement
We present filtering equations for single shot parameter estimation using
continuous quantum measurement. By embedding parameter estimation in the
standard quantum filtering formalism, we derive the optimal Bayesian filter for
cases when the parameter takes on a finite range of values. Leveraging recent
convergence results [van Handel, arXiv:0709.2216 (2008)], we give a condition
which determines the asymptotic convergence of the estimator. For cases when
the parameter is continuous valued, we develop quantum particle filters as a
practical computational method for quantum parameter estimation.Comment: 9 pages, 5 image
Revitalizing the HERO within Teachers: An Analysis of the Effects of the PsyCap Development Training
The purpose of the study was to investigate middle school teachers’ perceptions of the effects of a teacher-targeted intervention, that is, Psychological Capital Development Training Intervention (PCDTI), aiming at enhancing positive psychological capacities of teachers. The PCDTI was prepared and implemented by the researchers at a state university in a large city in Turkey during the academic year of 2014-2015. The implementation of the PCDTI lasted for 2 months, once in a week, and after completing the training intervention, interviews were conducted with twelve teachers who were the participants in the experimental group. Data were gathered through one-on-one interviews and were analyzed using qualitative content analysis. The participants stated that the PCDTI had some positive effects in terms of their personal and professional awareness and development. Raising awareness about some key issues in teachers’ lives, experiencing positive emotions, cognitions, and attitudes, and experiencing changes in their attitudes towards students and teaching profession were the perceived effects of the training intervention. The participants also made suggestions to enhance the effectiveness of the intervention. Some implications are offered for the benefits of enhancing teachers’ psychological capital in schools
Properties of nonaqueous electrolytes Quarterly report, 20 Jun. - 19 Sep. 1967
Electrolyte preparation, and physical property and nuclear magnetic resonance structural studies of nonaqueous electrolyte
Magnetometry via a double-pass continuous quantum measurement of atomic spin
We argue that it is possible in principle to reduce the uncertainty of an
atomic magnetometer by double-passing a far-detuned laser field through the
atomic sample as it undergoes Larmor precession. Numerical simulations of the
quantum Fisher information suggest that, despite the lack of explicit
multi-body coupling terms in the system's magnetic Hamiltonian, the parameter
estimation uncertainty in such a physical setup scales better than the
conventional Heisenberg uncertainty limit over a specified but arbitrary range
of particle number N. Using the methods of quantum stochastic calculus and
filtering theory, we demonstrate numerically an explicit parameter estimator
(called a quantum particle filter) whose observed scaling follows that of our
calculated quantum Fisher information. Moreover, the quantum particle filter
quantitatively surpasses the uncertainty limit calculated from the quantum
Cramer-Rao inequality based on a magnetic coupling Hamiltonian with only
single-body operators. We also show that a quantum Kalman filter is
insufficient to obtain super-Heisenberg scaling, and present evidence that such
scaling necessitates going beyond the manifold of Gaussian atomic states.Comment: 17 pages, updated to match print versio
Multiple Object Tracking in Urban Traffic Scenes with a Multiclass Object Detector
Multiple object tracking (MOT) in urban traffic aims to produce the
trajectories of the different road users that move across the field of view
with different directions and speeds and that can have varying appearances and
sizes. Occlusions and interactions among the different objects are expected and
common due to the nature of urban road traffic. In this work, a tracking
framework employing classification label information from a deep learning
detection approach is used for associating the different objects, in addition
to object position and appearances. We want to investigate the performance of a
modern multiclass object detector for the MOT task in traffic scenes. Results
show that the object labels improve tracking performance, but that the output
of object detectors are not always reliable.Comment: 13th International Symposium on Visual Computing (ISVC
Quantum measurement of a mesoscopic spin ensemble
We describe a method for precise estimation of the polarization of a
mesoscopic spin ensemble by using its coupling to a single two-level system.
Our approach requires a minimal number of measurements on the two-level system
for a given measurement precision. We consider the application of this method
to the case of nuclear spin ensemble defined by a single electron-charged
quantum dot: we show that decreasing the electron spin dephasing due to nuclei
and increasing the fidelity of nuclear-spin-based quantum memory could be
within the reach of present day experiments.Comment: 8 pages, 2 figures; minor changes, published versio
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