94 research outputs found
Heavy-tailed distributions in fatal traffic accidents: role of human activities
Human activities can play a crucial role in the statistical properties of
observables in many complex systems such as social, technological and economic
systems. We demonstrate this by looking into the heavy-tailed distributions of
observables in fatal plane and car accidents. Their origin is examined and can
be understood as stochastic processes that are related to human activities.
Simple mathematical models are proposed to illustrate such processes and
compared with empirical results obtained from existing databanks.Comment: 10 pages, 5 figure
Muon Pair Production by Electron-Photon Scatterings
The cross section for muon pair productions by electrons scattering over
photons, , is calculated analytically in the leading order. It is
pointed out that for the center-of-mass energy range, ,
the cross section for is less than b. The differential
energy spectrum for either of the resulting muons is given for the purpose of
high-energy neutrino astronomy. An implication of our result for a recent
suggestion concerning the high-energy cosmic neutrino generation through this
muon pair is discussed.Comment: a comment added, to appear in Phys. Rev. D, Rapid Communicatio
On Analytic Properties of the Photon Polarization Function in a Background Magnetic Field
We examine the analytic properties of the photon polarization function in a
background magnetic field, using the technique of inverse Mellin transform. The
photon polarization function is first expressed as a power series of the photon
energy with . Based upon this energy expansion and the
branch cut of the photon polarization function in the complex plane,
we compute the absorptive part of the polarization function with the inverse
Mellin transform. Our results are valid for arbitrary photon energies and
magnetic-field strengths. The applications of our approach are briefly
discussed.Comment: Revtex, 8 pages; Eq. (33) corrected, results of the paper not
affecte
A new look at the pair-production width in a strong magnetic field
We reexamine the process in a background magnetic field
comparable to . This process is known to be non-perturbative
in the magnetic-field strength. However, it can be shown that the {\it moments}
of the above pair production width is proportional to the derivatives of photon
polarization function at the zero energy, which is perturbative in . Hence,
the pair-production width can be easily obtained from the latter by the inverse
Mellin transform. The implications of our approach are discussed.Comment: 8 pages, 2 figures, Revtex, Some comments adde
Post-activation Performance Enhancement after a Bout of Accentuated Eccentric Loading in Collegiate Male Volleyball Players
The purpose of this study was to investigate the benefit of post-activation performance enhancement (PAPE) after accentuated eccentric loading (AEL) compared to traditional resistance loading (TR). Sixteen male volleyball athletes were divided in AEL and TR group. AEL group performed 3 sets of 4 repetitions (eccentric: 105% of concentric 1RM, concentric: 80% of concentric 1RM) of half squat, and TR group performed 3 sets of 5 repetitions (eccentric & concentric: 85% of 1RM). Countermovement jump (CMJ), spike jump (SPJ), isometric mid-thigh pull (IMTP), and muscle soreness test were administered before (Pre) exercise, and 10 min (10-min), 24 h (24-h), and 48 h (48-h) after exercise. A two-way repeated measures analysis of variance was used to analyze the data. Peak force and rate of development (RFD) of IMTP in AEL group were significantly greater (p 0.05) groups x time. AEL seemed capable to maintain force production in IMTP, but not in CMJ and SPJ. It is recommended the use of accentuated eccentric loading protocols to overcome the fatigue
Neutrino-photon scattering and its crossed processes in a background magnetic field
We study the neutrino-photon processes such as
and in a background magnetic field smaller than the
critical magnetic field . Using Schwinger's proper-time
method, we extract leading magnetic-field contributions to the above processes.
Our result is valid throughout the kinematic regime where both neutrino and
photon energies are significantly smaller than . We briefly discuss the
astrophysical implications of our result.Comment: Revtex, 10 pages, 4 ps figures, to appear in Phys. Lett.
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