653 research outputs found
Coastal sea surface temperature variability along the south coast of South Africa and the relationship to regional and global climate
The southern coastline of South Africa is approximately zonal, with a wide (up to 270 km) shelf region. Intense thermoclines are known to be established by insolation on the inner shelf region during summer, upwelling is generated by easterly-component winds, and occasionally Agulhas Current water can be advected close to the coast, particularly in the east. These processes induce daily and seasonal fluctuations of coastal sea-surface temperature (SST), but their influence over longer time scales (interannual) has not yet been tested. Here time series of SST ranging from 12 to 31 years are examined for inter-relationships with local and regional winds, and the southern oscillation index (SOI). The emphasis is on the summer period, and it is found that the correlation between SST and major axis wind anomalies can be improved substantially by considering the frequency of occurrence of winds above given thresholds. Moreover, winds and SSTs are also correlated with the SOI, such that fewer easterly-component winds are experienced at low phases (El Nino) with consequent increases in coastal SST, and correspondingly more easterly-component winds at high phases (La Nina) result in decreased coastal SST; however, these relationships did not hold for a measuring site within a large open bay area. Long-term trends are also established, with substantial increases in SST (0.25°C/decade) in association with greater increases in air temperature (0.36°C/ decade)
A Cellular Automata Model with Probability Infection and Spatial Dispersion
In this article, we have proposed an epidemic model by using probability
cellular automata theory. The essential mathematical features are analyzed with
the help of stability theory. We have given an alternative modelling approach
for the spatiotemporal system which is more realistic and satisfactory from the
practical point of view. A discrete and spatiotemporal approach are shown by
using cellular automata theory. It is interesting to note that both size of the
endemic equilibrium and density of the individual increase with the increasing
of the neighborhood size and infection rate, but the infections decrease with
the increasing of the recovery rate. The stability of the system around the
positive interior equilibrium have been shown by using suitable Lyapunov
function. Finally experimental data simulation for SARS disease in China and a
brief discussion conclude the paper
Persistent random walk on a one-dimensional lattice with random asymmetric transmittances
We study the persistent random walk of photons on a one-dimensional lattice
of random asymmetric transmittances. Each site is characterized by its
intensity transmittance t (t') for photons moving to the right (left)
direction. Transmittances at different sites are assumed independent,
distributed according to a given probability density Distribution. We use the
effective medium approximation and identify two classes of probability density
distribution of transmittances which lead to the normal diffusion of photons.
Monte Carlo simulations confirm our predictions.Comment: 7 pages, submitted to Phys. Rev.
CONTROL ROD DRIVE PROTO-TYPE TEST REPORT
An evaluation under simulated Pathfinder reactor operating conditions of a prototype Pathfinder control rod drive (described) indicated that the unit will perform satisfactorily under all Pathfinder operating conditions. Tests were performed on individual components of the drive and on the assembled drive. (D.C.W.
Boundedness, compactness and Schatten-class membership of weighted composition operators
The boundedness and compactness of weighted composition operators on the
Hardy space of the unit disc is analysed. Particular reference
is made to the case when the self-map of the disc is an inner function.
Schatten-class membership is also considered; as a result, stronger forms of
the two main results of a recent paper of Gunatillake are derived. Finally,
weighted composition operators on weighted Bergman spaces are considered, and the results of Harper and Smith,
linking their properties to those of Carleson embeddings, are extended to this
situation.Comment: 12 page
De novo mutations in EIF2B1 affecting eIF2 signaling cause neonatal/early onset diabetes and transient hepatic dysfunction
This is the author accepted manuscript. The final version is available from the American Diabetes Association via the DOI in this recordData and resource availability. EIF2B1 mutation details have been deposited in the Decipher
database (https://decipher.sanger.ac.uk/). All other data sets generated and/or analysed for this study
are available from the corresponding author upon reasonable request.Permanent neonatal diabetes is caused by reduced β-cell number or impaired β-cell function.
Understanding the genetic basis of this disorder highlights fundamental β-cell mechanisms.
We performed trio genome sequencing for 44 permanent neonatal diabetes patients and their
unaffected parents to identify causative de novo variants. Replication studies were performed in 188
patients diagnosed with diabetes before 2 years of age without a genetic diagnosis.
EIF2B1 (encoding the eIF2B complex α subunit) was the only gene with novel de novo variants (all
missense) in at least three patients. Replication studies identified 2 further patients with de novo
EIF2B1 variants. In addition to diabetes, 4/5 patients had hepatitis-like episodes in childhood. The
EIF2B1 de novo mutations were found to map to the same protein surface. We propose that these
variants render the eIF2B complex insensitive to eIF2 phosphorylation which occurs under stress
conditions and triggers expression of stress-response genes. Failure of eIF2B to sense eIF2
phosphorylation likely leads to unregulated unfolded protein response and cell death.
Our results establish de novo EIF2B1 mutations as a novel cause of permanent diabetes and liver
dysfunction. These findings confirm the importance of cell stress regulation for β-cells and highlight
EIF2B1’s fundamental role within this pathway.European Foundation for the Study of DiabetesDiabetes UKDiabetes Research and Wellness FoundationWellcome TrustNational Institute for Health Research (NIHR)Royal Societ
Increased Neural Activity in Mesostriatal Regions after Prefrontal Transcranial Direct Current Stimulation and<sub> L</sub>-DOPA Administration
Persistence exponents in a 3D symmetric binary fluid mixture
The persistence exponent, theta, is defined by N_F sim t^theta, where t is
the time since the start of the coarsening process and the "no-flip fraction",
N_F, is the number of points that have not seen a change of "color" since t=0.
Here we investigate numerically the persistence exponent for a binary fluid
system where the coarsening is dominated by hydrodynamic transport. We find
that N_F follows a power law decay (as opposed to exponential) with the value
of theta somewhat dependent on the domain growth rate (L sim t^alpha, where L
is the average domain size), in the range theta=1.23 +-0.1 (alpha = 2/3) to
theta=1.37 +-0.2 (alpha=1). These alpha values correspond to the inertial and
viscous hydrodynamic regimes respectively.Comment: 9 pages RevTex, 9 figures included as eps files on last 3 pages,
submitted to Phys Rev
3D Spinodal Decomposition in the Inertial Regime
We simulate late-stage coarsening of a 3D symmetric binary fluid using a
lattice Boltzmann method. With reduced lengths and times l and t respectively
(scales set by viscosity, density and surface tension) our data sets cover 1 <
l
100 we find clear evidence of Furukawa's inertial scaling (l ~ t^{2/3}),
although the crossover from the viscous regime (l ~ t) is very broad. Though it
cannot be ruled out, we find no indication that Re is self-limiting (l ~
t^{1/2}) as proposed by M. Grant and K. R. Elder [Phys. Rev. Lett. 82, 14
(1999)].Comment: 4 pages, 3 eps figures, RevTex, minor changes to bring in line with
published version. Mobility values added to Table
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Assessment of photoplethysmographic signals for the determination of splanchnic oxygen saturation in humans
The need for a clinically applicable method of detecting splanchnic hypoxia has led to experimental animal studies which indicated the usefulness of intestinal pulse oximetry. Pulse oximetry relies on detection of photoplethysmographic signals. Before developing a pulse oximeter for the measurement of organ oxygen saturation peri-operatively, we designed a system based on a reflectance photoplethysmographic probe to investigate photoplethysmographic signals from human viscera (bowel, liver, and kidney). Recordings were obtained simultaneously from the abdominal viscera and the finger using identical probes. The probe was held sequentially for up to 2 min on the surface of viscera of 12 patients during routine laparotomy. Measurable splanchnic photoplethysmographic signals were recorded for the first time in humans. There were no statistically significant differences between photoplethysmographic amplitudes from viscera and those from the finger. Our results indicate the feasibility of pulse oximetry for the measurement of visceral oxygenation in humans
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