377 research outputs found
Low-Mass Dileptons at the CERN-SpS: Evidence for Chiral Restoration?
Using a rather complete description of the in-medium spectral function
- being constrained by various independent experimental information - we
calculate pertinent dilepton production rates from hot and dense hadronic
matter. The strong broadening of the resonance entails a reminiscence to
perturbative annihilation rates in the vicinity of the phase
boundary. The application to dilepton observables in Pb(158AGeV)+Au collisions
- incorporating recent information on the hadro-chemical composition at
CERN-SpS energies - essentially supports the broadening scenario. Possible
implications for the nature of chiral symmetry restoration are outlined.Comment: 6 pages ReVTeX including 5 eps-figure
On the Changes in the Electrical Conductivity of Thermo-electrets and Magneto- Electrets States of Some Solid Dielectrics
Nonequilibrium fluctuation induced escape from a metastable state
Based on a simple microscopic model where the bath is in a non-equilibrium
state we study the escape from a metastable state in the over-damped limit.
Making use of Fokker-Planck-Smoluchowski description we derive the time
dependent escape rate in the non-stationary regime in closed analytical form
which brings on to fore a strong non-exponential kinetic of the system mode.Comment: 4 pages, no figures, EPJ class file include
Dynamics of a metastable state nonlinearly coupled to a heat bath driven by an external noise
Based on a system-reservoir model, where the system is nonlinearly coupled to
a heat bath and the heat bath is modulated by an external stationary Gaussian
noise, we derive the generalized Langevin equation with space dependent
friction and multiplicative noise and construct the corresponding Fokker-Planck
equation, valid for short correlation time, with space dependent diffusion
coefficient to study the escape rate from a metastable state in the moderate to
large damping regime. By considering the dynamics in a model cubic potential we
analyze the result numerically which are in good agreement with the theoretical
prediction. It has been shown numerically that the enhancement of rate is
possible by properly tuning the correlation time of the external noise.Comment: 13 pages, 5 figures, Revtex4. To appear in Physical Review
Escape rate from a metastable state weakly interacting with a heat bath driven by an external noise
Based on a system-reservoir model, where the reservoir is driven by an
external stationary, Gaussian noise with arbitrary decaying correlation
function, we study the escape rate from a metastable state in the energy
diffusion regime. For the open system we derive the Fokker-Planck equation in
the energy space and subsequently calculate the generalized non-Markovian
escape rate from a metastable well in the energy diffusion domain. By
considering the dynamics in a model cubic potential we show that the results
obtained from numerical simulation are in good agreement with the theoretical
prediction. It has been also shown numerically that the well known turnover
feature can be restored from our model.Comment: 11 pages, 2 figure
The noise properties of stochastic processes and entropy production
Based on a Fokker-Planck description of external Ornstein-Uhlenbeck noise and
cross-correlated noise processes driving a dynamical system we examine the
interplay of the properties of noise processes and the dissipative
characteristic of the dynamical system in the steady state entropy production
and flux. Our analysis is illustrated with appropriate examples.Comment: RevTex, 1 figure, To appear in Phys. Rev.
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Dreaming Characteristics in Non-Rapid Eye Movement Parasomnia and Idiopathic Rapid Eye Movement Sleep Behaviour Disorder: Similarities and Differences
Background: Speech graph analysis (SGA) of dreams has recently shown promise as an objective and language-invariant diagnostic tool that can aid neuropsychiatric diagnosis. Whilst the notion that dreaming mentations reflect distinct physiologic processes is not new, such studies in patients with sleep disorders remain exceptionally scarce. Here, using SGA and other dream content analyses, we set to investigate structural and thematic differences in morning dream recalls of patients diagnosed with Non-Rapid Eye Movement Parasomnia (NREMP) and Idiopathic REM Sleep Behavior Disorder (iRBD). Methods: A retrospective cross-sectional study of morning dream recalls of iRBD and NREMP patients was undertaken. Traditional dream content analyses, such as Orlinsky and Hall and Van de Castle analyses, were initially conducted. Subsequently, SGA was performed in order to objectively quantify structural speech differences between the dream recalls of the two patient groups. Results: Comparable rate of morning recall of dreams in the sleep laboratory was recorded; 25% of iRBD and 18.35% of NREMP patients. Aggression in dreams was recorded by 28.57% iRBD versus 20.00% in NREMP group. iRBD patients were more likely to recall dreams (iRBD vs NREMP; P = 0.007), but they also had more white dreams, ie having a feeling of having dreamt, but with no memory of it. Visual and quantitative graph speech analyses of iRBD dreams suggested stable sequential structure, reflecting the linearity of the chronological narrative. Conversely, NREMP dream reports displayed more recursive, less stable systems, with significantly higher scores of graph connectivity measures. Conclusion: The findings of our exploratory study suggest that iRBD and NREMP patients may not only differ on what is recalled in their dreams but also, perhaps more strikingly, on how dreams are recalled. It is hoped that future SGA-led dream investigations of larger groups of patients will help discern distinct mechanistic underpinnings and any associated clinical implications
Theory of Adiabatic fluctuations : third-order noise
We consider the response of a dynamical system driven by external adiabatic
fluctuations. Based on the `adiabatic following approximation' we have made a
systematic separation of time-scales to carry out an expansion in , where is the strength of fluctuations and is the
damping rate. We show that probability distribution functions obey the
differential equations of motion which contain third order terms (beyond the
usual Fokker-Planck terms) leading to non-Gaussian noise. The problem of
adiabatic fluctuations in velocity space which is the counterpart of Brownian
motion for fast fluctuations, has been solved exactly. The characteristic
function and the associated probability distribution function are shown to be
of stable form. The linear dissipation leads to a steady state which is stable
and the variances and higher moments are shown to be finite.Comment: Plain Latex, no figures, 28 pages; to appear in J. Phys.
The Non-Motor Symptoms Scale in Parkinson's disease: validation and use
The Non‐Motor Symptoms Scale (NMSS) was developed and validated in 2007 as the first instrument for the comprehensive assessment of a range of non‐motor symptoms in Parkinson's disease (PD). Thirteen years have elapsed since its introduction and extensive international validation with good psychometric attributes has been carried out. Here, we review the validation data of the NMSS and its cross‐validity with other scales, and describe the key evidence derived from use of the NMSS in clinical studies. To date, over 100 clinical studies and trials have made use of it as an outcome measure, showing consistent and strong correlations between NMSS burden and health‐related quality of life measures. Moreover, the scale has shown to be capable of detecting longitudinal changes in non‐motor symptoms, where studies have shown differential changes over time of several of the NMSS domains. The scale has become a key outcome in several randomized clinical trials. Highlighting the prevalence and importance of non‐motor symptoms to quality of life in patients with PD, the development of NMSS has also been useful in signposting clinical and biomarker based research addressing non‐motor symptoms in PD
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