13,985 research outputs found
Parental stress increases body mass index trajectory in pre-adolescents.
What is already known about this subjectRates of childhood obesity have increased since the mid-1970s. Research into behavioural determinants has focused on physical inactivity and unhealthy diets. Cross-sectional studies indicate an association between psychological stress experienced by parents and obesity in pre-adolescents.What this study addsWe provide evidence of a prospective association between parental psychological stress and increased weight gain in pre-adolescents. Family-level support for those experiencing chronic stress might help promote healthy diet and exercise behaviours in children.ObjectiveWe examined the impact of parental psychological stress on body mass index (BMI) in pre-adolescent children over 4 years of follow-up.MethodsWe included 4078 children aged 5-10 years (90% were between 5.5 and 7.5 years) at study entry (2002-2003) in the Children's Health Study, a prospective cohort study in southern California. A multi-level linear model simultaneously examined the effect of parental stress at study entry on the attained BMI at age 10 and the slope of change across annual measures of BMI during follow-up, controlled for the child's age and sex. BMI was calculated based on objective measurements of height and weight by trained technicians following a standardized procedure.ResultsA two standard deviation increase in parental stress at study entry was associated with an increase in predicted BMI attained by age 10 of 0.287 kg m(-2) (95% confidence interval 0.016-0.558; a 2% increase at this age for a participant of average attained BMI). The same increase in parental stress was also associated with an increased trajectory of weight gain over follow-up, with the slope of change in BMI increased by 0.054 kg m(-2) (95% confidence interval 0.007-0.100; a 7% increase in the slope of change for a participant of average BMI trajectory).ConclusionsWe prospectively demonstrated a small effect of parental stress on BMI at age 10 and weight gain earlier in life than reported previously. Interventions to address the burden of childhood obesity should address the role of parental stress in children
Stability of Filters for the Navier-Stokes Equation
Data assimilation methodologies are designed to incorporate noisy
observations of a physical system into an underlying model in order to infer
the properties of the state of the system. Filters refer to a class of data
assimilation algorithms designed to update the estimation of the state in a
on-line fashion, as data is acquired sequentially. For linear problems subject
to Gaussian noise filtering can be performed exactly using the Kalman filter.
For nonlinear systems it can be approximated in a systematic way by particle
filters. However in high dimensions these particle filtering methods can break
down. Hence, for the large nonlinear systems arising in applications such as
weather forecasting, various ad hoc filters are used, mostly based on making
Gaussian approximations. The purpose of this work is to study the properties of
these ad hoc filters, working in the context of the 2D incompressible
Navier-Stokes equation. By working in this infinite dimensional setting we
provide an analysis which is useful for understanding high dimensional
filtering, and is robust to mesh-refinement. We describe theoretical results
showing that, in the small observational noise limit, the filters can be tuned
to accurately track the signal itself (filter stability), provided the system
is observed in a sufficiently large low dimensional space; roughly speaking
this space should be large enough to contain the unstable modes of the
linearized dynamics. Numerical results are given which illustrate the theory.
In a simplified scenario we also derive, and study numerically, a stochastic
PDE which determines filter stability in the limit of frequent observations,
subject to large observational noise. The positive results herein concerning
filter stability complement recent numerical studies which demonstrate that the
ad hoc filters perform poorly in reproducing statistical variation about the
true signal
Hand motion pattern recognition analysis of forearm muscle using MMG signals
Surface Mechanomyography (MMG) is the recording of mechanical activity of muscle tissue. MMG measures the mechanical signal (vibration of muscle) that generated from the muscles during contraction or relaxation action. It is widely used in various fields such as medical diagnosis, rehabilitation purpose and engineering applications. The main purpose of this research is to identify the hand gesture movement via VMG sensor (TSD250A) and classify them using Linear Discriminant Analysis (LDA). There are four channels MMG signal placed into adjacent muscles which PL-FCU and ED-ECU. The features used to feed the classifier to determine accuracy are mean absolute value, standard deviation, variance and root mean square. Most of subjects gave similar range of MMG signal of extraction values because of the adjacent muscle. The average accuracy of LDA is approximately 87.50% for the eight subjects. The finding of the result shows, MMG signal of adjacent muscle can affect the classification accuracy of the classifier
What counts as ‘responding’? Contingency on previous speaker contribution as a feature of interactional competence
The ability to interact with others has gained recognition as part of the L2 speaking construct in the assessment literature and in high- and low-stakes speaking assessments. This paper first presents a review of the literature on interactional competence (IC) in L2 learning and assessment. It then discusses a particular feature – producing responses contingent on previous speaker contribution – that emerged as a de facto construct feature of IC oriented to by both candidates and examiners within the school-based group speaking assessment in the Hong Kong Diploma of Secondary Education (HKDSE) English Language Examination. Previous studies have, similarly, argued for the importance of ‘responding to’ or linking one’s own talk to previous speakers’ contributions as a way of demonstrating comprehension of co-participants’ talk. However, what counts as such a response has yet to be explored systematically. This paper presents a conversation analytic study of the candidate discourse in the assessed group interactions, identifying three conversational actions through which student-candidates construct contingent responses to co-participants. The thick description about the nature of contingent responses lays the groundwork for further empirical investigations on the relevance of this IC feature and its proficiency implications
Resolving the Large-N Nuclear Potential Puzzle
The large nuclear potential puzzle arose because three- and
higher-meson exchange contributions to the nucleon-nucleon potential did not
automatically yield cancellations that make these contributions consistent with
the general large scaling rules for the potential. Here it is proposed
that the resolution to this puzzle is that the scaling rules only apply for
energy-independent potentials while all of the cases with apparent
inconsistencies were for energy-dependent potentials. It is shown explicitly
how energy-dependent potentials can have radically different large N behavior
than an equivalent energy-independent one. One class of three-meson graphs is
computed in which the contribution to the energy-independent potential is
consistent with the general large N rules even though the energy-dependent
potential is not.Comment: Corrections to the toy mode
K2 Variable Catalogue: Variable Stars and Eclipsing Binaries in K2 Campaigns 1 and 0
We have created a catalogue of variable stars found from a search of the
publicly available K2 mission data from Campaigns 1 and 0. This catalogue
provides the identifiers of 8395 variable stars, including 199 candidate
eclipsing binaries with periods up to 60d and 3871 periodic or quasi-periodic
objects, with periods up to 20d for Campaign 1 and 15d for Campaign 0.
Lightcurves are extracted and detrended from the available data. These are
searched using a combination of algorithmic and human classification, leading
to a classifier for each object as an eclipsing binary, sinusoidal periodic,
quasi periodic, or aperiodic variable. The source of the variability is not
identified, but could arise in the non-eclipsing binary cases from pulsation or
stellar activity. Each object is cross-matched against variable star related
guest observer proposals to the K2 mission, which specifies the variable type
in some cases. The detrended lightcurves are also compared to lightcurves
currently publicly available. The resulting catalogue is made available online
via the MAST archive at https://archive.stsci.edu/prepds/k2varcat/, and gives
the ID, type, period, semi-amplitude and range of the variation seen. We also
make available the detrended lightcurves for each object.Comment: Accepted by A&A. 6 pages, 6 figures. Catalogue and lightcurves are
available online via MAST at https://archive.stsci.edu/prepds/k2varcat
Spontaneous Magnetization of Composite Fermions
It is argued that the composite fermion liquid is a promising candidate for
an observation of the elusive, interaction driven magnetization first proposed
by Bloch seven decades ago. In analogy to what is theoretically believed to be
the case for the idealized electron gas in zero magnetic field, this
spontaneously broken symmetry phase is predicted to occur prior to a transition
into the Wigner crystal.Comment: 5 pages, 4 figure
Wigner Crystallization of a two dimensional electron gas in a magnetic field: single electrons versus electron pairs at the lattice sites
The ground state energy and the lowest excitations of a two dimensional
Wigner crystal in a perpendicular magnetic field with one and two electrons per
cell is investigated. In case of two electrons per lattice site, the
interaction of the electrons {\em within} each cell is taken into account
exactly (including exchange and correlation effects), and the interaction {\em
between} the cells is in second order (dipole) van der Waals approximation. No
further approximations are made, in particular Landau level mixing and {\em
in}complete spin polarization are accounted for. Therefore, our calculation
comprises a, roughly speaking, complementary description of the bubble phase
(in the special case of one and two electrons per bubble), which was proposed
by Koulakov, Fogler and Shklovskii on the basis of a Hartree Fock calculation.
The phase diagram shows that in GaAs the paired phase is energetically more
favorable than the single electron phase for, roughly speaking, filling factor
larger than 0.3 and density parameter smaller than 19 effective Bohr
radii (for a more precise statement see Fig.s 4 and 5). If we start within the
paired phase and increase magnetic field or decrease density, the pairs first
undergo some singlet- triplet transitions before they break.Comment: 11 pages, 7 figure
Stripe State in the Lowest Landau Level
The stripe state in the lowest Landau level is studied by the density matrix
renormalization group (DMRG) method. The ground state energy and pair
correlation functions are systematically calculated for various
pseudopotentials in the lowest Landau level. We show that the stripe state in
the lowest Landau level is realized only in a system whose width perpendicular
to the two-dimensional electron layer is smaller than the order of magnetic
length.Comment: 4 pages, 6 figures, to appear in J. Phys. Soc. Jpn. vol.73 No.1
(2004
Testing J/psi Production and Decay Properties in Hadronic Collisions
The polar and azimuthal angular distributions for the lepton pair arising
from the decay of a J/psi meson produced at transverse momentum p_T balanced by
a photon [or gluon] in hadronic collisions are calculated in the color singlet
model (CSM). It is shown that the general structure of the decay lepton
distribution is controlled by four invariant structure functions, which are
functions of the transverse momentum and the rapidity of the J/psi. We found
that two of these structure functions [the longitudinal and transverse
interference structure functions] are identical in the CSM. Analytical and
numerical results are given in the Collins-Soper and in the Gottfried-Jackson
frame. We present a Monte Carlo study of the effect of acceptance cuts applied
to the leptons and the photon for J/psi+ gamma production at the Tevatron.Comment: 22 pages (LaTeX) plus 11 postscript figures, MAD/PH/822, YUMS94-11.
Figures are available from the authors or as a compressed tar file via
anonymous ftp at phenom.physics.wisc.edu in directory
{}~pub/preprints/madph-94-822-figs.tar.
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