851 research outputs found
The early identification of risk factors on the pathway to school dropout in the SIODO study:A sequential mixed-methods study
BACKGROUND: School dropout is a persisting problem with major socioeconomic consequences. Although poor health probably contributes to pathways leading to school dropout and health is likely negatively affected by dropout, these issues are relatively absent on the public health agenda. This emphasises the importance of integrative research aimed at identifying children at risk for school dropout at an early stage, discovering how socioeconomic status and gender affect health-related pathways that lead to dropout and developing a prevention tool that can be used in public health services for youth. METHODS/DESIGN: The SIODO study is a sequential mixed-methods study. A case–control study will be conducted among 18 to 24 year olds in the south of the Netherlands (n = 580). Data are currently being collected from compulsory education departments at municipalities (dropout data), regional public health services (developmental data from birth onwards) and an additional questionnaire has been sent to participants (e.g. personality data). Advanced analyses, including cluster and factor analyses, will be used to identify children at risk at an early stage. Using the quantitative data, we have planned individual interviews with participants and focus groups with important stakeholders such as parents, teachers and public health professionals. A thematic content analysis will be used to analyse the qualitative data. DISCUSSION: The SIODO study will use a life-course perspective, the ICF-CY model to group the determinants and a mixed-methods design. In this respect, the SIODO study is innovative because it both broadens and deepens the study of health-related determinants of school dropout. It examines how these determinants contribute to socioeconomic and gender differences in health and contributes to the development of a tool that can be used in public health practice to tackle the problem of school dropout at its roots
Mode locking of vortex matter driven through mesoscopic channels
We investigated the driven dynamics of vortices confined to mesoscopic flow
channels by means of a dc-rf interference technique. The observed mode-locking
steps in the -curves provide detailed information on how the number of rows
and lattice structure in the channel change with magnetic field. Minima in flow
stress occur when an integer number of rows is moving coherently, while maxima
appear when incoherent motion of mixed and row configurations is
predominant. Simulations show that the enhanced pinning at mismatch originates
from quasi-static fault zones with misoriented edge dislocations induced by
disorder in the channel edges.Comment: some minor changes were made, 4 pages, 4 figures, accepted for
publication in Phys. Rev. Let
Vortex lattices in strong type-II superconducting two-dimensional strips
We show how to calculate semi-analytically the dense vortex state in strong
type-II superconducting nanostructures. For the specific case of a strip, we
find vortex lattice solutions which also incorporate surface superconductivity.
We calculate the energy cost to displace individual vortex rows parallel to the
surfaces and find that this energy oscillates with the magnetic field.
Remarkably, we also find that, at a critical field below , this
''shear'' energy becomes strictly zero for the surface rows due to an
unexpected mismatch with the bulk lattice.Comment: Title, abstract, and some text paragraphs have been rewritte
Nonlocal Conductivity in the Vortex-Liquid Regime of a Two-Dimensional Superconductor
We have simulated the time-dependent Ginzburg-Landau equation with thermal
fluctuations, to study the nonlocal dc conductivity of a superconducting film.
Having examined points in the phase diagram at a wide range of temperatures and
fields below the mean-field upper critical field, we find a portion of the
vortex-liquid regime in which the nonlocal ohmic conductivity in real space is
negative over a distance several times the spacing between vortices. The effect
is suppressed when driven beyond linear response. Earlier work had predicted
the existence of such a regime, due to the high viscosity of a
strongly-correlated vortex liquid. This behavior is clearly distinguishable
from the monotonic spatial fall-off of the conductivity in the higher
temperature or field regimes approaching the normal state. The possibilities
for experimental study of the nonlocal transport properties are discussed.Comment: 18 pages, revtex, 6 postscript figure
Effect of Pulsed or Continuous Delivery of Salt on Sensory Perception Over Short Time Intervals
Salt in the human diet is a major risk factor for hypertension and many countries have set targets to reduce
salt consumption. Technological solutions are being sought
to lower the salt content of processed foods without altering their taste. In this study, the approach was to deliver salt solutions in pulses of different concentrations to determine whether a pulsed delivery profile affected sensory perception of salt. Nine different salt profiles were delivered by a Dynataste device and a trained panel assessed their saltiness using time–intensity and single-score sensory techniques. The profile duration (15 s) was designed to match eating conditions and the effects of intensity and duration of the pulses on sensory perception were investigated. Sensory results from the profiles delivered in either water or in a bouillon base were not statistically different. Maximum perceived salt intensities and the area under the time–
intensity curves correlated well with the overall perceived
saltiness intensity despite the stimulus being delivered as
several pulses. The overall saltiness scores for profiles
delivering the same overall amount of sodium were statistically not different from one another suggesting that, in this system, pulsed delivery did not enhance salt
perception but the overall amount of salt delivered in each
profile did affect sensory perception
Entropy and information in neural spike trains: Progress on the sampling problem
The major problem in information theoretic analysis of neural responses and
other biological data is the reliable estimation of entropy--like quantities
from small samples. We apply a recently introduced Bayesian entropy estimator
to synthetic data inspired by experiments, and to real experimental spike
trains. The estimator performs admirably even very deep in the undersampled
regime, where other techniques fail. This opens new possibilities for the
information theoretic analysis of experiments, and may be of general interest
as an example of learning from limited data.Comment: 7 pages, 4 figures; referee suggested changes, accepted versio
Patterned Geometries and Hydrodynamics at the Vortex Bose Glass Transition
Patterned irradiation of cuprate superconductors with columnar defects allows
a new generation of experiments which can probe the properties of vortex
liquids by confining them to controlled geometries. Here we show that an
analysis of such experiments that combines an inhomogeneous Bose glass scaling
theory with the hydrodynamic description of viscous flow of vortex liquids can
be used to infer the critical behavior near the Bose glass transition. The
shear viscosity is predicted to diverge as at the Bose glass
transition, with the dynamical critical exponent.Comment: 5 pages, 4 figure
Vortex Motion Noise in Micrometre-Sized Thin Films of the Amorphous Nb0.7Ge0.3 Weak-Pinning Superconductor
We report high-resolution measurements of voltage (V) noise in the mixed
state of micrometre-sized thin films of amorphous Nb0.7Ge0.3, which is a good
representative of weak-pinning superconductors. There is a remarkable
difference between the noise below and above the irreversibility field Birr.
Below Birr, in the presence of measurable pinning, the noise at small applied
currents resembles shot noise, and in the regime of flux flow at larger
currents decreases with increasing voltage due to a progressive ordering of the
vortex motion. At magnetic fields B between Birr and the upper critical field
Bc2 flux flow is present already at vanishingly small currents. In this regime
the noise scales with (1-B/Bc2)^2 V^2 and has a frequency (f) spectrum of 1/f
type. We interpret this noise in terms of the properties of strongly driven
depinned vortex systems at high vortex density.Comment: 8 pages, 5 figures, version accepted for publication in PR
Dynamic ordering and frustration of confined vortex rows studied by mode-locking experiments
The flow properties of confined vortex matter driven through disordered
mesoscopic channels are investigated by mode locking (ML) experiments. The
observed ML effects allow to trace the evolution of both the structure and the
number of confined rows and their match to the channel width as function of
magnetic field. From a detailed analysis of the ML behavior for the case of
3-rows we obtain ({\it i}) the pinning frequency , ({\it ii}) the onset
frequency for ML ( ordering velocity) and ({\it iii}) the
fraction of coherently moving 3-row regions in the channel. The
field dependence of these quantities shows that, at matching, where is
maximum, the pinning strength is small and the ordering velocity is low, while
at mismatch, where is small, both the pinning force and the ordering
velocity are enhanced. Further, we find that , consistent
with the dynamic ordering theory of Koshelev and Vinokur. The microscopic
nature of the flow and the ordering phenomena will also be discussed.Comment: 10 pages, 7 figure, submitted to PRB. Discussion has been improved
and a figure has been adde
First effective mHealth nutrition and lifestyle coaching program for subfertile couples undergoing in vitro fertilization treatment:a single-blinded multicenter randomized controlled trial
Objective: To study compliance and effectiveness of the mHealth nutrition and lifestyle coaching program Smarter Pregnancy in couples undergoing in vitro fertilization (IVF) treatment with or without intracytoplasmic sperm injection (ICSI). Design: Multicenter, single-blinded, randomized controlled trial, conducted from July 2014 to March 2017. Setting: IVF clinics. Patient(s): A total of 626 women undergoing IVF treatment with or without ICSI and 222 male partners. Interventions(s): Couples were randomly assigned to the light (control group) or regular (intervention group) Smarter Pregnancy program. Both groups filled out a baseline screening questionnaire on nutrition and lifestyle behaviors, and the intervention group received coaching tailored to inadequate behaviors during the 24-week period. Main Outcome Measure(s): Difference in improvement of a composite dietary and lifestyle risk score for the intake of vegetables, fruits, folic acid supplements, smoking, and alcohol use after 24 weeks of the program. Result(s): Compared with control subjects, women and men in the intervention group showed a significantly larger improvement of inadequate nutrition behaviors after 24 weeks of coaching. At the same time, the women also showed a significantly larger improvement of inadequate lifestyle behaviors. Conclusion(s): The mHealth coaching program Smarter Pregnancy is effective and improves the most important nutritional and lifestyle behaviors among couples undergoing IVF/ICSI treatment. International multicenter randomized trials are recommended to study the effect of using Smarter Pregnancy on pregnancy, live birth, and neonatal outcome. ((C)2020 by American Society for Reproductive Medicine.)y
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