15,830 research outputs found
Solar Sources of Interplanetary Magnetic Clouds Leading to Helicity Prediction
This study identifies the solar origins of magnetic clouds that are observed
at 1 AU and predicts the helical handedness of these clouds from the solar
surface magnetic fields. We started with the magnetic clouds listed by the
Magnetic Field Investigation (MFI) team supporting NASA's WIND spacecraft in
what is known as the MFI table and worked backwards in time to identify solar
events that produced these clouds. Our methods utilize magnetograms from the
Helioseismic and Magnetic Imager (HMI) instrument on the Solar Dynamics
Observatory (SDO) spacecraft so that we could only analyze MFI entries after
the beginning of 2011. This start date and the end date of the MFI table gave
us 37 cases to study. Of these we were able to associate only eight surface
events with clouds detected by WIND at 1 AU. We developed a simple algorithm
for predicting the cloud helicity which gave the correct handedness in all
eight cases. The algorithm is based on the conceptual model that an ejected
flux tube has two magnetic origination points at the positions of the strongest
radial magnetic field regions of opposite polarity near the places where the
ejected arches end at the solar surface. We were unable to find events for the
remaining 29 cases: lack of a halo or partial halo CME in an appropriate time
window, lack of magnetic and/or filament activity in the proper part of the
solar disk, or the event was too far from disk center. The occurrence of a
flare was not a requirement for making the identification but in fact flares,
often weak, did occur for seven of the eight cases.Comment: 18 pages, 8 figures, 2 table
A continuum-microscopic method based on IRBFs and control volume scheme for viscoelastic fluid flows
A numerical computation of continuum-microscopic model for visco-elastic flows based on the Integrated Radial Basis Function (IRBF) Control Volume and the Stochastic Simulation Techniques (SST) is reported in this paper. The macroscopic flow equations are closed by a stochastic equation for the extra stress at the microscopic level. The former are discretised by a 1D-IRBF-CV method while the latter is integrated with Euler explicit or Predictor-Corrector schemes. Modelling is very efficient as it is based on Cartesian grid, while the integrated RBF approach enhances both the stability of the procedure and the accuracy of the solution. The proposed method is demonstrated with the solution of the start-up Couette flow of the Hookean and FENE dumbbell model fluids
The Anticorrelated Nature of the Primary and Secondary Eclipse Timing Variations for the Kepler Contact Binaries
We report on a study of eclipse timing variations in contact binary systems,
using long-cadence lightcurves in the Kepler archive. As a first step,
'observed minus calculated' (O-C) curves were produced for both the primary and
secondary eclipses of some 2000 Kepler binaries. We find ~390 short-period
binaries with O-C curves that exhibit (i) random-walk like variations or
quasi-periodicities, with typical amplitudes of +/- 200-300 seconds, and (ii)
anticorrelations between the primary and secondary eclipse timing variations.
We present a detailed analysis and results for 32 of these binaries with
orbital periods in the range of 0.35 +/- 0.05 days. The anticorrelations
observed in their O-C curves cannot be explained by a model involving mass
transfer, which among other things requires implausibly high rates of ~0.01
M_sun per year. We show that the anticorrelated behavior, the amplitude of the
O-C delays, and the overall random-walk like behavior can be explained by the
presence of a starspot that is continuously visible around the orbit and slowly
changes its longitude on timescales of weeks to months. The quasi-periods of
~50-200 days observed in the O-C curves suggest values for k, the coefficient
of the latitude dependence of the stellar differential rotation, of
~0.003-0.013.Comment: Published in The Astrophysical Journal, 2013, Vol. 774, p.81; 14
pages, 12 figures, and 2 table
DeepCare: A Deep Dynamic Memory Model for Predictive Medicine
Personalized predictive medicine necessitates the modeling of patient illness
and care processes, which inherently have long-term temporal dependencies.
Healthcare observations, recorded in electronic medical records, are episodic
and irregular in time. We introduce DeepCare, an end-to-end deep dynamic neural
network that reads medical records, stores previous illness history, infers
current illness states and predicts future medical outcomes. At the data level,
DeepCare represents care episodes as vectors in space, models patient health
state trajectories through explicit memory of historical records. Built on Long
Short-Term Memory (LSTM), DeepCare introduces time parameterizations to handle
irregular timed events by moderating the forgetting and consolidation of memory
cells. DeepCare also incorporates medical interventions that change the course
of illness and shape future medical risk. Moving up to the health state level,
historical and present health states are then aggregated through multiscale
temporal pooling, before passing through a neural network that estimates future
outcomes. We demonstrate the efficacy of DeepCare for disease progression
modeling, intervention recommendation, and future risk prediction. On two
important cohorts with heavy social and economic burden -- diabetes and mental
health -- the results show improved modeling and risk prediction accuracy.Comment: Accepted at JBI under the new name: "Predicting healthcare
trajectories from medical records: A deep learning approach
Water soluble fluorescent carbon nanodots from biosource for cells imaging
Carbon nanodots (CNDs) derived from a green precursor, kidney beans, was synthesized with high yield via a facile pyrolysis technique. The CND material was easily modified through simple oxidative treatment with nitric acid, leading to a high density “self-passivated” water soluble form (wsCNDs). The synthesized wsCNDs have been extensively characterized by using various microscopic and spectroscopic techniques and were crystalline in nature. The highly carboxylated wsCNDs possessed tunable-photoluminescence emission behavior throughout the visible region of the spectrum, demonstrating their application for multicolor cellular imaging of HeLa cells. The tunable-photoluminescence properties of “self-passivated” wsCNDs make them a promising candidate as a probe in biological cell-imaging applications.Kumud Malika Tripathi, Tuan Sang Tran, Tran Thanh Tung, Dusan Losic and TaeYoung Ki
Euclidean-signature Supergravities, Dualities and Instantons
We study the Euclidean-signature supergravities that arise by compactifying
D=11 supergravity or type IIB supergravity on a torus that includes the time
direction. We show that the usual T-duality relation between type IIA and type
IIB supergravities compactified on a spatial circle no longer holds if the
reduction is performed on the time direction. Thus there are two inequivalent
Euclidean-signature nine-dimensional maximal supergravities. They become
equivalent upon further spatial compactification to D=8. We also show that
duality symmetries of Euclidean-signature supergravities allow the harmonic
functions of any single-charge or multi-charge instanton to be rescaled and
shifted by constant factors. Combined with the usual diagonal dimensional
reduction and oxidation procedures, this allows us to use the duality
symmetries to map any single-charge or multi-charge p-brane soliton, or any
intersection, into its near-horizon regime. Similar transformations can also be
made on non-extremal p-branes. We also study the structures of duality
multiplets of instanton and (D-3)-brane solutions.Comment: Latex, 50 pages, typos corrected and references adde
Protocol for an economic evaluation alongside a cluster randomised controlled trial: cost-effectiveness of Learning Clubs, a multicomponent intervention to improve women’s health and infant’s health and development in Vietnam
Introduction: Economic evaluations of complex interventions in early child development are required to guide policy and programme development, but a few are yet available.
Methods and analysis: Although significant gains have been made in maternal and child health in resource- constrained environments, this has mainly been concentrated on improving physical health. The Learning Clubs programme addresses both physical and mental child and maternal health. This study is an economic evaluation of a cluster randomised controlled trial of the impact of the Learning Clubs programme in Vietnam. It will be conducted from a societal perspective and aims to identify the cost-effectiveness and the economic and social returns of the intervention. A total of 1008 pregnant women recruited from 84 communes in a rural province in Vietnam will be included in the evaluation. Health and cost data will be gathered at three stages of the trial and used to calculate incremental cost-effectiveness ratios per percentage point improvement of infant’s development, infant’s health and maternal common mental disorders expressed in quality-adjusted life years gained. The return on investment will be calculated based on improvements in productivity, the results being expressed as benefit–cost ratios.
Ethics and dissemination: The trial was approved by Monash University Human Research Ethics Committee (Certificate Number 2016–0683), Australia, and approval was extended to include the economic evaluation (Amendment Review Number 2018-0683-23806); and the Institutional Review Board of the Hanoi School of Public Health (Certificate Number 017-377IDD- YTCC), Vietnam. Results will be disseminated through academic journals and conference presentations
A molecular perspective on the limits of life: Enzymes under pressure
From a purely operational standpoint, the existence of microbes that can grow
under extreme conditions, or "extremophiles", leads to the question of how the
molecules making up these microbes can maintain both their structure and
function. While microbes that live under extremes of temperature have been
heavily studied, those that live under extremes of pressure have been
neglected, in part due to the difficulty of collecting samples and performing
experiments under the ambient conditions of the microbe. However, thermodynamic
arguments imply that the effects of pressure might lead to different organismal
solutions than from the effects of temperature. Observationally, some of these
solutions might be in the condensed matter properties of the intracellular
milieu in addition to genetic modifications of the macromolecules or repair
mechanisms for the macromolecules. Here, the effects of pressure on enzymes,
which are proteins essential for the growth and reproduction of an organism,
and some adaptations against these effects are reviewed and amplified by the
results from molecular dynamics simulations. The aim is to provide biological
background for soft matter studies of these systems under pressure.Comment: 16 pages, 8 figure
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