38,045 research outputs found
Generalizing Amdahl’s Law for Power and Energy
Extending Amdahl\u27s law to identify optimal power-performance configurations requires considering the interactive effects of power, performance, and parallel overhead
Molecular Dynamics Simulation of Macromolecules Using Graphics Processing Unit
Molecular dynamics (MD) simulation is a powerful computational tool to study
the behavior of macromolecular systems. But many simulations of this field are
limited in spatial or temporal scale by the available computational resource.
In recent years, graphics processing unit (GPU) provides unprecedented
computational power for scientific applications. Many MD algorithms suit with
the multithread nature of GPU. In this paper, MD algorithms for macromolecular
systems that run entirely on GPU are presented. Compared to the MD simulation
with free software GROMACS on a single CPU core, our codes achieve about 10
times speed-up on a single GPU. For validation, we have performed MD
simulations of polymer crystallization on GPU, and the results observed
perfectly agree with computations on CPU. Therefore, our single GPU codes have
already provided an inexpensive alternative for macromolecular simulations on
traditional CPU clusters and they can also be used as a basis to develop
parallel GPU programs to further speedup the computations.Comment: 21 pages, 16 figure
MEASURING THE RETURNS TO AGRICULTURAL EXPERIMENT STATION RESEARCH EXPENDITURES FOR CORN, WHEAT AND SOYBEANS
Research and Development/Tech Change/Emerging Technologies,
Determination of the Sign of g factors for Conduction Electrons Using Time-resolved Kerr Rotation
The knowledge of electron g factor is essential for spin manipulation in the
field of spintronics and quantum computing. While there exist technical
difficulties in determining the sign of g factor in semiconductors by the
established magneto-optical spectroscopic methods. We develop a time resolved
Kerr rotation technique to precisely measure the sign and the amplitude of
electron g factor in semiconductors
Characterizing time series : when Granger causality triggers complex networks
In this paper, we propose a new approach to characterize time series with noise perturbations in both the time and frequency domains by combining Granger causality and complex networks. We construct directed and weighted complex networks from time series and use representative network measures to describe their physical and topological properties. Through analyzing the typical dynamical behaviors of some physical models and the MIT-BIH* human electrocardiogram data sets, we show that the proposed approach is able to capture and characterize various dynamics and has much potential for analyzing real-world time series of rather short length
Residual Symmetries for Neutrino Mixing with a Large theta_13 and Nearly Maximal delta_D
The residual Z^s_2(k) and bar Z^s_2(k) symmetries induce a direct and unique
phenomenological relation with theta_x (= theta_13) expressed in terms of the
other two mixing angles, theta_s (= theta_12) and theta_a (= theta_23), and the
Dirac CP phase delta_D. Z^s_2(k) predicts a theta_x probability distribution
centered around 3^o ~ 6^o with an uncertainty of 2^o to 4^o while those from
bar Z^s_2(k) are approximately a factor of two larger. Either result fits the
T2K, MINOS and Double CHOOZ measurements. Alternately a prediction for the
Dirac CP phase delta_D results in a peak at +-74^o (+-106^o) for Z^s_2(k) or
+-123^o (+-57^o) for bar Z^s_2(k) which is consistent with the latest global
fit. We also give a distribution for the leptonic Jarslkog invariant J_v which
can provide further tests from measurements at T2K and NOvA.Comment: Accepted for publication in PR
Application of Instantons: Quenching of Macroscopic Quantum Coherence and Macroscopic Fermi-Particle Configurations
Starting from the coherent state representation of the evolution operator
with the help of the path-integral, we derive a formula for the low-lying
levels of a quantum spin
system. The quenching of macroscopic quantum coherence is understood as the
vanishing of in disagreement with the suppression of tunneling
(i.e. ) as claimed in the literature. A new
configuration called the macroscopic Fermi-particle is suggested by the
character of its wave function. The tunneling rate
() does not vanish, not for integer spin s nor for
a half-integer value of s, and is calculated explicitly (for the position
dependent mass) up to the one-loop approximation.Comment: 13 pages, LaTex, no figure
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