574 research outputs found
Note on the Kaplan-Yorke dimension and linear transport coefficients
A number of relations between the Kaplan-Yorke dimension, phase space
contraction, transport coefficients and the maximal Lyapunov exponents are
given for dissipative thermostatted systems, subject to a small external field
in a nonequilibrium stationary state. A condition for the extensivity of phase
space dimension reduction is given. A new expression for the transport
coefficients in terms of the Kaplan-Yorke dimension is derived. Alternatively,
the Kaplan-Yorke dimension for a dissipative macroscopic system can be
expressed in terms of the transport coefficients of the system. The agreement
with computer simulations for an atomic fluid at small shear rates is very
good.Comment: 12 pages, 5 figures, submitted to J. Stat. Phy
The current practice of intra-aortic balloon counterpulsation: results from the Benchmark Registry
OBJECTIVES This study presents clinical data from the first large registry of aortic counterpulsation, a computerized database that incorporates prospectively gathered data on indications for intra-aortic balloon counterpulsation (IABP) use, patient demographics, concomitant medication and in-hospital outcomes and complications. BACKGROUND The intra-aortic balloon pump (IABP) is widely used to provide circulatory support for patients experiencing hemodynamic instability due to myocardial infarction, cardiogenic shock, or in very high risk patients undergoing angioplasty or coronary artery bypass grafting. METHODS Between June 1996 and August 2000, 203 hospitals worldwide (90% U.S., 10% non-U.S.) collected 16,909 patient case records (68.8% men, 31.2% women; mean age 65.9 ± 11.7 years). RESULTS The most frequent indications for use of IABP were as follows: to provide hemodynamic support during or after cardiac catheterization (20.6%), cardiogenic shock (18.8%), weaning from cardiopulmonary bypass (16.1%), preoperative use in high risk patients (13.0%) and refractory unstable angina (12.3%). Major IABP complications (major limb ischemia, severe bleeding, balloon leak, death directly due to IABP insertion or failure) occurred in 2.6% of cases; in-hospital mortality was 21.2% (11.6% with the balloon in place). Female gender, high age and peripheral vascular disease were independent predictors of a serious complication. CONCLUSIONS This registry provides a useful tool for monitoring the evolving practice of IABP. In the modern-day practice of IABP, complication rates are generally low, although in-hospital mortality remains high. There is an increased risk of major complications in women, older patients and patients with peripheral vascular disease
Boundary condition independence of molecular dynamics simulations of planar elongational flow
The simulation of liquid systems in a nonequilibrium steady state under planar elongational flow (PEF) for indefinite time is possible only with the use of the so-called Kraynik-Reinelt (KR) periodic boundary conditions (PBCs) on the simulation cell. These conditions admit a vast range of implementation parameters, which regulate how the unit lattice is deformed under elongation and periodically remapped onto itself. Clearly, nonequilibrium properties of homogeneous systems in a steady state have to be independent of the boundary conditions imposed on the unit cell. In order to confirm the independence of measurable properties of a system under PEF from the particular set of periodic boundary conditions, we compute the Lyapunov spectra, apply the conjugate pairing rule, and carefully analyze the so-called unpaired exponents for an atomic fluid of various sizes and state points. We further compute the elongational viscosity for various implementations of boundary conditions. All our results confirm the independence from KR PBCs for the dynamics of phase-space trajectories and for the transport coefficients
Causality, response theory, and the second law of thermodynamics
We show that there is a close connection between the assumption of causality and the second law of thermodynamics. We also show that for a class of classical reversible deterministic systems it is overwhelmingly improbable either to find causal steady states that violate the second law, or anticausal states that satisfy the second law. These arguments indicate that the existence of (and the sign associated with) the second law of thermodynamics is ultimately determined by causality. Our discussion employs a Green-Kubo relation that we derive for an anticausal linear transport coefficient
Linking proactive personality and the Big Five to motivation to learn and development activity.
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Psychiatric intensive care units: A literature review
Background: Psychiatric Intensive Care Units (PICU) have been part of most inpatient psychiatric services for some time, however information about their functioning and outcome has not previously been collated.
Aim: To conduct a systematic literature review to assess the current state of knowledge about such services.
Method: A search of electronic databases was undertaken, followed by obtaining additional references from items obtained.
Results: Over 50 papers in English containing some empirical data were identified. Most studies were retrospective. Typical PICU patients are: male; younger; single; unemployed; suffering from schizophrenia or mania; from a black Caribbean or African background; legally detained; with a forensic history. The most common reason for admission is for aggression management, and most patients stay a week or less. Evidence of the efficacy of PICU care is very poor.
Conclusions: Most research so far has been small scale, and more substantial work using better methodologies is clearly required
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Mainstreaming domestic and gender-based violence into sociology and the criminology of violence
Sociological and criminological views of domestic and gender-based violencegenerally either dismiss it as not worthy of consideration, or focus on specificgroups of offenders and victims (male youth gangs, partner violence victims). Inthis paper, we take a holistic approach to violence, extending the definition fromthat commonly in use to encompass domestic violence and sexual violence. Weoperationalize that definition by using data from the latest sweep of the CrimeSurvey for England and Wales. By so doing, we identify that violence is currentlyunder-measured and ubiquitous; that it is gendered, and that other forms of violence (family violence, acquaintance violence against women) are equally ofconcern. We argue that violence studies are an important form of activity forsociologists
Methamphetamine Use and Methicillin-Resistant Staphylococcus aureus Skin Infections
Drug use may be contributing to the spread of MRSA in a rural southeastern US community
First narrow-band search for continuous gravitational waves from known pulsars in advanced detector data
Spinning neutron stars asymmetric with respect to their rotation axis are potential sources of
continuous gravitational waves for ground-based interferometric detectors. In the case of known pulsars a
fully coherent search, based on matched filtering, which uses the position and rotational parameters
obtained from electromagnetic observations, can be carried out. Matched filtering maximizes the signalto-
noise (SNR) ratio, but a large sensitivity loss is expected in case of even a very small mismatch
between the assumed and the true signal parameters. For this reason, narrow-band analysis methods have
been developed, allowing a fully coherent search for gravitational waves from known pulsars over a
fraction of a hertz and several spin-down values. In this paper we describe a narrow-band search of
11 pulsars using data from Advanced LIGO’s first observing run. Although we have found several initial
outliers, further studies show no significant evidence for the presence of a gravitational wave signal.
Finally, we have placed upper limits on the signal strain amplitude lower than the spin-down limit for 5 of
the 11 targets over the bands searched; in the case of J1813-1749 the spin-down limit has been beaten for
the first time. For an additional 3 targets, the median upper limit across the search bands is below the
spin-down limit. This is the most sensitive narrow-band search for continuous gravitational waves carried
out so far
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