2,707 research outputs found
Combining real and virtual Higgs boson mass constraints
Within the framework of the standard model we observe that there is a
significant discrepancy between the most precise boson decay asymmetry
measurement and the limit from direct searches for Higgs boson production.
Using methods inspired by the Particle Data Group we explore the possible
effect on fits of the Higgs boson mass. In each case the central value and the
95% confidence level upper limit increase significantly relative to the
conventional fit. The results suggest caution in drawing conclusions about the
Higgs boson mass from the existing data.Comment: 11 pages, Latex. Citations are added and paper is otherwise
reconciled with version to be published in Physical Review Letter
Finite-time quantum-to-classical transition for a Schroedinger-cat state
The transition from quantum to classical, in the case of a quantum harmonic
oscillator, is typically identified with the transition from a quantum
superposition of macroscopically distinguishable states, such as the
Schr\"odinger cat state, into the corresponding statistical mixture. This
transition is commonly characterized by the asymptotic loss of the interference
term in the Wigner representation of the cat state. In this paper we show that
the quantum to classical transition has different dynamical features depending
on the measure for nonclassicality used. Measures based on an operatorial
definition have well defined physical meaning and allow a deeper understanding
of the quantum to classical transition. Our analysis shows that, for most
nonclassicality measures, the Schr\"odinger cat dies after a finite time.
Moreover, our results challenge the prevailing idea that more macroscopic
states are more susceptible to decoherence in the sense that the transition
from quantum to classical occurs faster. Since nonclassicality is prerequisite
for entanglement generation our results also bridge the gap between
decoherence, which appears to be only asymptotic, and entanglement, which may
show a sudden death. In fact, whereas the loss of coherences still remains
asymptotic, we have shown that the transition from quantum to classical can
indeed occur at a finite time.Comment: 9+epsilon pages, 4 figures, published version. Originally submitted
as "Sudden death of the Schroedinger cat", a bit too cool for APS policy :-
Online learning: Examining instructional design strategies in leisure curriculum
An assessment of the park and recreation-related educational programs and departments within the United States indicates an increasing presence of web-based distance learning (WBDL) environments. According to a voluntary listing posted on NRPA’s official website, over 35 courses are offered within a WBDL environment with almost 20 U.S. colleges and universities participating. In addition, some programs currently offer a 100% WBDL baccalaureate and/or master degree. These numbers are also somewhat conservative as additional programs offered by universities continue to emerge as evident by the dialogue and postings on the online discussion forum of the Society of Park and Recreation Educators (SPREnet). With this increase in instructional technologies there has been a growing concern in the educational community regarding the effectiveness of these tools to meet the needs of the learners (Lukow & Ross, 2003; Van Dusen & Worthen, 1995). Despite this concern, many of the issues surrounding the effective implementation of WBDL programs have not been explored sufficiently. Grounded within social cognitive theory, this study examined the instructional design of a WBDL about pay-for-performance systems in parks and recreation. The effects of two instructional methods, online discussion groups and multiple formats, are assessed on cognitive outcomes. The moderating role of experience with technology, technology selfefficacy, and several individual characteristic variables were also examined
Weak electron scattering for the 3He-3H transition and the weak nuclear form factors
We calculate the differential cross section for weak electron scattering reaction, e + 3He-\u27 3H + ve, for energies from 100 MeV to 6 GeV as a function of outgoing nucleus angle from 0 to n/2 radians. We find that the differential cross section at low [q2] increases with electron energy from 0.1 GeV to 6.0 GeV, such that the peak value at 6.0 GeV is approximately 3.2 x 10-40 cm 2 / ster, a factor of 10 larger than the peak value at 0.1 GeV. We also find that the width of the peak falls very rapidly with increasing electron energy. At high [q2] we find that the differential cross section falls by approximately three orders of magnitude making experimental observation at this time unlikely. The contributions of the individual form factors are obtained for electron energies of 0.5GeV and 2.0 GeV. It is found that at low [q2] the form factors, FA(q2) and Fv(q2), make contributions of similar size to the differential cross section and might be simultaneously determined , but for the case of FM(q2) we find that the contribution is too small to determine. It is also found that at large [q2] values, the contribution of FM(q2) is substantially enhanced , but that the cross section is probably too small to enable a direct determination of FM(q2)
Influence of oxidative stress, diaphragm fatigue, and inspiratory muscle training on the plasma cytokine response to maximum sustainable voluntary ventilation
The influence of oxidative stress, diaphragm fatigue, and inspiratory muscle training (IMT) on the cytokine response to maximum sustainable voluntary ventilation (MSVV) is unknown. Twelve healthy males were divided equally into an IMT or placebo (PLA) group, and before and after a 6-wk intervention they undertook, on separate days, 1h of (1) passive rest and (2) MSVV, whereby participants undertook volitional hyperpnea at rest that mimicked the breathing and respiratory muscle recruitment patterns commensurate with heavy cycling exercise. Plasma cytokines remained unchanged during passive rest. There was a main effect of time (P < 0.01) for plasma interleukin-1 (IL-1) and interleukin-6 (IL-6) concentrations and a strong trend (P = 0.067) for plasma interleukin-1 receptor antagonist concentration during MSVV. Plasma IL-6 concentration was reduced after IMT by 27 + 18% (main effect of intervention, P = 0.029), whereas there was no change after PLA (P = 0.753). There was no increase in a systemic marker of oxidative stress [DNA damage in peripheral blood mononuclear cells (PBMC)], and diaphragm fatigue was not related to the increases in plasma IL-1 and IL-6 concentrations. A dose-response relationship was observed between respiratory muscle work and minute ventilation and increases in plasma IL-6 concentration. In conclusion, increases in plasma IL-1 and IL-6 concentrations during MSVV were not due to diaphragm fatigue or DNA damage in PBMC. Increases in plasma IL-6 concentration during MSVV are attenuated following IMT, and the plasma IL-6 response is dependent upon the level of respiratory muscle work and minute ventilation
Decoherence due to three-body loss and its effect on the state of a Bose-Einstein condensate
A Born-Markov master equation is used to investigate the decoherence of the
state of a macroscopically occupied mode of a cold atom trap due to three-body
loss. In the large number limit only coherent states remain pure for times
longer than the decoherence time: the time it takes for just three atoms to be
lost from the trap. For large numbers of atoms (N>10^4) the decoherence time is
found to be much faster than the phase collapse time caused by intra-trap
atomic collisions
Stigma as a fundamental hindrance to the United States opioid overdose crisis response.
Alexander Tsai and co-authors discuss the role of stigma in responses to the US opioid crisis
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