3,178 research outputs found
Polarisation rotation of slow light with orbital angular momentum in ultracold atomic gases
We consider the propagation of slow light with an orbital angular momentum
(OAM) in a moving atomic medium. We have derived a general equation of motion
and applied it in analysing propagation of slow light with an OAM in a rotating
medium, such as a vortex lattice. We have shown that the OAM of slow light
manifests itself in a rotation of the polarisation plane of linearly polarised
light. To extract a pure rotational phase shift, we suggest to measure a
difference in the angle of the polarisation plane rotation by two consecutive
light beams with opposite OAM. The differential angle is
proportional to the rotation frequency of the medium
and the winding number of light, and is inversely proportional to the
group velocity of light. For slow light the angle should
be large enough to be detectable. The effect can be used as a tool for
measuring the rotation frequency of the medium.Comment: 5 pages, 1 figur
Business Ethics and Corporate Growth
This study was carried out to ascertain the impact of business ethical code of conduct on corporate growth in the wake of several corporate fraud, misstatement and misrepresentation. This study employed the survey research design. Business ethics and corporate growth questionnaire (BECGQ) was developed and 100 of the BECGQ were administered, out of which 80 were completely filled and returned. The Pearson product moment correlation was used to test the analysed data at 50% significance level. The study revealed that adoption of business ethical code of conduct and employee adherence to rules and regulations enhance corporate growth. The study also revealed that there is no significant relationship between corporate growth and corporate adherence to rules and regulations. The study therefore recommended that business ethics should be align with the corporate structure, goals and culture in order to enhance corporate growth. Key words: Business ethics, Corporate growth, rules and regulation
Research utility of noninvasive methods for measurement of cardiac output
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109853/1/cptclpt198751.pd
Bottom water export from the western Ross Sea, 2007 through 2010
Bottom water export from the Ross Sea, February 2007 to January 2011, exhibits seasonal and interannual variability. Temperature minima coupled to salinity maxima in late austral summer, into the fall, indicate input from High-Salinity Shelf Water (HSSW). Secondary temperature minima lacking the high-salinity trait, characteristic of Low-Salinity Shelf Water (LSSW), appear in the spring. Warmer bottom water similar to modified Circumpolar Deep Water (mCDW) is observed in winter and in early summer. The LSSW and mCDW may be drawn from the Drygalski Basin, as the HSSW pool retreats poleward from the shelf break in response to increased winter polar easterlies allowing these less dense overlying waters to spill into the deep ocean within the benthic layer. Bottom salinity decreased from 2007 to 2011 by 0.007 year−1 significantly higher than regional decadal trends, which we propose is a result of HSSW retreat induced by strengthening polar easterlies
Using a neural network approach to accelerate disequilibrium chemistry calculations in exoplanet atmospheres
In this era of exoplanet characterisation with JWST, the need for a fast
implementation of classical forward models to understand the chemical and
physical processes in exoplanet atmospheres is more important than ever.
Notably, the time-dependent ordinary differential equations to be solved by
chemical kinetics codes are very time-consuming to compute. In this study, we
focus on the implementation of neural networks to replace mathematical
frameworks in one-dimensional chemical kinetics codes. Using the gravity
profile, temperature-pressure profiles, initial mixing ratios, and stellar flux
of a sample of hot-Jupiters atmospheres as free parameters, the neural network
is built to predict the mixing ratio outputs in steady state. The architecture
of the network is composed of individual autoencoders for each input variable
to reduce the input dimensionality, which is then used as the input training
data for an LSTM-like neural network. Results show that the autoencoders for
the mixing ratios, stellar spectra, and pressure profiles are exceedingly
successful in encoding and decoding the data. Our results show that in 90% of
the cases, the fully trained model is able to predict the evolved mixing ratios
of the species in the hot-Jupiter atmosphere simulations. The fully trained
model is ~1000 times faster than the simulations done with the forward,
chemical kinetics model while making accurate predictions.Comment: 13 pages, 9 figures, accepted for publication at MNRA
The role of perceived source location in auditory stream segregation: separation affects sound organization, common fate does not
The human auditory system is capable of grouping sounds originating from different sound sources into coherent auditory streams, a process termed auditory stream segregation. Several cues can influence auditory stream segregation, but the full set of cues and the way in which they are integrated is still unknown. In the current study, we tested whether auditory motion can serve as a cue for segregating sequences of tones. Our hypothesis was that, following the principle of common fate, sounds emitted by sources moving together in space along similar trajectories will be more likely to be grouped into a single auditory stream, while sounds emitted by independently moving sources will more often be heard as two streams. Stimuli were derived from sound recordings in which the sound source motion was induced by walking humans. Although the results showed a clear effect of spatial separation, auditory motion had a negligible influence on stream segregation. Hence, auditory motion may not be used as a primitive cue in auditory stream segregation
Correlation between tumor necrosis factor-alpha and septic shock in children
Background The crucial role cytokines play in the pathophysiology
of sepsis is widely accepted. Infection stimulates the production
of cytokines in various cell types. Tumor necrosis factor-alpha
(TNF-a) is one of the most extensively investigated cytokines in
experimental and clinical sepsis. Tumor necrosis factor-alpha has
been shown to mediate lethality in experimental sepsis.
Objective To evaluate for a possible correlation between TNF-a
level and septic shock in children.
Methods This cross-sectional study was conducted in Manado
from June to September 2011. A total of 40 patients with a
recent diagnosis of sepsis or septic shock were included. Plasma
specimens were collected from subjects for measurement of
TNF-a concentration. Logistic regression analysis was used to
assess the correlation between TNF-a level and sepsis, as well as
the probability of shock in children with sepsis, with P<0.05 as
statistically significant.
Results There was a strong positive correlation between
TNF-a level and the probability of shock in children with sepsis
(regression coefficient = 0. 78, P = 0.002).
Conclusions There is a strong positive correlation between
TNF-a level with the probability of shock in children with sepsis.
Higher plasma level ofTNF-a is associated with higher probability
of septic shock
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Differences Among Subtropical Surface Salinity Patterns
The subtropical ocean, exposed to evaporation excess over precipitation, is characterized by regional sea surface salinity maxima (SSS-max). Ocean circulation and mixing processes inject freshwater, establishing a quasi-steady state, though imbalances across the time spectrum result in periods of increasing and decreasing SSS-max. The integrated effect of the array of atmospheric and oceanic forces governing sea surface salinity is shaped by the specific regional ocean basin configuration as well as their coupling to the global ocean system, resulting in SSS-max patterns and locations that display marked differences between the subtropical regimes. We provide a brief description of the SSS-max characteristics of the five subtropical regimes and present aspects of their regional settings that may account for their dissimilarities
Relationship of Transmural Variations in Myofiber Contractility to Left Ventricular Ejection Fraction: Implications for Modeling Heart Failure Phenotype With Preserved Ejection Fraction
The pathophysiological mechanisms underlying preserved left ventricular (LV) ejection fraction (EF) in patients with heart failure and preserved ejection fraction (HFpEF) remain incompletely understood. We hypothesized that transmural variations in myofiber contractility with existence of subendocardial dysfunction and compensatory increased subepicardial contractility may underlie preservation of LVEF in patients with HFpEF. We quantified alterations in myocardial function in a mathematical model of the human LV that is based on the finite element method. The fiber-reinforced material formulation of the myocardium included passive and active properties. The passive material properties were determined such that the diastolic pressure-volume behavior of the LV was similar to that shown in published clinical studies of pressure-volume curves. To examine changes in active properties, we considered six scenarios: (1) normal properties throughout the LV wall; (2) decreased myocardial contractility in the subendocardium; (3) increased myocardial contractility in the subepicardium; (4) myocardial contractility decreased equally in all layers, (5) myocardial contractility decreased in the midmyocardium and subepicardium, (6) myocardial contractility decreased in the subepicardium. Our results indicate that decreased subendocardial contractility reduced LVEF from 53.2 to 40.5%. Increased contractility in the subepicardium recovered LVEF from 40.5 to 53.2%. Decreased contractility transmurally reduced LVEF and could not be recovered if subepicardial and midmyocardial contractility remained depressed. The computational results simulating the effects of transmural alterations in the ventricular tissue replicate the phenotypic patterns of LV dysfunction observed in clinical practice. In particular, data for LVEF, strain and displacement are consistent with previous clinical observations in patients with HFpEF, and substantiate the hypothesis that increased subepicardial contractility may compensate for subendocardial dysfunction and play a vital role in maintaining LVEF
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