8,733 research outputs found
Heart Rate Patterns Observed in Medical Monitoring
Medical monitoring of heart rate patterns during conditions of sleep, quiet rest, breath-holding, hypoxia, and increased g forces of aircraft fligh
Theory of quantum paraelectrics and the metaelectric transition
We present a microscopic model of the quantum paraelectric-ferroelectric
phase transition with a focus on the influence of coupled fluctuating phonon
modes. These may drive the continuous phase transition first order through a
metaelectric transition and furthermore stimulate the emergence of a textured
phase that preempts the transition. We discuss two further consequences of
fluctuations, firstly for the heat capacity, and secondly we show that the
inverse paraelectric susceptibility displays T^2 quantum critical behavior, and
can also adopt a characteristic minimum with temperature. Finally, we discuss
the observable consequences of our results.Comment: 5 pages, 2 figure
A repulsive atomic gas in a harmonic trap on the border of itinerant ferromagnetism
Alongside superfluidity, itinerant (Stoner) ferromagnetism remains one of the
most well-characterized phases of correlated Fermi systems. A recent experiment
has reported the first evidence for novel phase behavior on the repulsive side
of the Feshbach resonance in a two-component ultracold Fermi gas. By adapting
recent theoretical studies to the atomic trap geometry, we show that an
adiabatic ferromagnetic transition would take place at a weaker interaction
strength than is observed in experiment. This discrepancy motivates a simple
non-equilibrium theory that takes account of the dynamics of magnetic defects
and three-body losses. The formalism developed displays good quantitative
agreement with experiment.Comment: 4 pages, 2 figure
Emergence of stability in a stochastically driven pendulum: beyond the Kapitsa effect
We consider a prototypical nonlinear system which can be stabilized by
multiplicative noise: an underdamped non-linear pendulum with a stochastically
vibrating pivot. A numerical solution of the pertinent Fokker-Planck equation
shows that the upper equilibrium point of the pendulum can become stable even
when the noise is white, and the "Kapitsa pendulum" effect is not at work. The
stabilization occurs in a strong-noise regime where WKB approximation does not
hold.Comment: 4 pages, 7 figure
Itinerant ferromagnetism in an atomic Fermi gas: Influence of population imbalance
We investigate ferromagnetic ordering in an itinerant ultracold atomic Fermi
gas with repulsive interactions and population imbalance. In a spatially
uniform system, we show that at zero temperature the transition to the
itinerant magnetic phase transforms from first to second order with increasing
population imbalance. Drawing on these results, we elucidate the phases present
in a trapped geometry, finding three characteristic types of behavior with
changing population imbalance. Finally, we outline the potential experimental
implications of the findings.Comment: 10 pages, 4 figures, typos added, references adde
Events, processes, and the time of a killing
The paper proposes a novel solution to the problem of the time of a killing (ToK), which persistently besets theories of act-individuation. The solution proposed claims to expose a crucial wrong-headed assumption in the debate, according to which ToK is essentially a problem of locating some event that corresponds to the killing. The alternative proposal put forward here turns on recognizing a separate category of dynamic occurents, viz. processes. The paper does not aim to mount a comprehensive defense of process ontology, relying instead on extant defenses. The primary aim is rather to put process ontology to work in diagnosing the current state of play over ToK, and indeed in solving it
Quasi-analytical formulation for calculation of infiltration and runoff
Prepared for USDA Forest Service, Rocky Mountain Forest and Range Experiment Station.CER81-82-86.December 1981.Bibliography: pages 41-42
Sedimentation study of the Yazoo River Basin. Phase II, General report
CER83-84DBS-RMLGOB22.Prepared for U.S. Army Corps of Engineers, Vicksburg District, Vicksburg, Mississippi.November 1983.Includes bibliographical references.Volume II: Appendices is born digital.Contract no. DACW 38-76-C-0193
Spectral statistics of disordered metals in the presence of several Aharonov-Bohm fluxes
The form factor for spectral correlations in a diffusive metal is calculated
in the presence of several Aharonov-Bohm fluxes. When the fluxes are
equal, the correlations are universal functions of where is
the dimensionless conductance and is the number of applied fluxes. This
explains recent flux dependence of the correlations found numerically at the
metal-insulator transition.Comment: 3 pages, Latex, 1 figure, to appear in Phys. Rev. B Rapid Com
- …