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The effect of feedback and information on children's pedometer step counts at school
This study examined whether feedback or feedback plus physical activity information could increase the number of pedometer steps taken during 1 school week. One hundred seventy-seven students (mean age 9.124 ± 1.11 years) in three elementary schools participated. Schools were randomly assigned to control (CON), feedback (FB), or feedback plus information (FB+I) groups. Children wore pedometers during school time for 5 consecutive weekdays. The total steps of the groups were recorded at the end of each school day, with students in the FB and FB+I groups free to view their step counts. In addition, the FB+I group received information and ideas about how they could increase their daily steps. The CON group received no step-count feedback or information. Students in the FB+I group achieved significantly more steps per minute (17.17 ± 4.87) than those in the FB (13.77 ± 4.06, p = 0.003) and CON (12.41 ± 3.12, p = 0.0001) groups. Information, as well as step-count feedback, increased elementary students’ school-based physical activity (number of steps) in the short term. A longer intervention period is necessary to assess the sustained impact of this type of approach
Breaking of the overall permutation symmetry in nonlinear optical susceptibilities of one-dimensional periodic dimerized Huckel model
Based on infinite one-dimensional single-electron periodic models of
trans-polyacetylene, we show analytically that the overall permutation symmetry
of nonlinear optical susceptibilities is, albeit preserved in the molecular
systems with only bound states, no longer generally held for the periodic
systems. The overall permutation symmetry breakdown provides a fairly natural
explanation to the widely observed large deviations of Kleinman symmetry for
periodic systems in off-resonant regions. Physical conditions to experimentally
test the overall permutation symmetry break are discussed.Comment: 7 pages, 1 figur
Searching in HI for Massive Low Surface Brightness Galaxies: Samples from HyperLeda and the UGC
A search has been made for 21 cm HI line emission in a total of 350 unique
galaxies from two samples whose optical properties indicate they may be massive
The first consists of 241 low surface brightness (LSB) galaxies of
morphological type Sb and later selected from the HyperLeda database and the
the second consists of 119 LSB galaxies from the UGC with morphological types
Sd-m and later. Of the 350 unique galaxies, 239 were observed at the Nancay
Radio Telescope, 161 at the Green Bank Telescope, and 66 at the Arecibo
telescope. A total of 295 (84.3%) were detected, of which 253 (72.3%) appear to
be uncontaminated by any other galaxies within the telescope beam. Finally, of
the total detected, uncontaminated galaxies, at least 31 appear to be massive
LSB galaxies, with a total HI mass 10 M, for H = 70
km/s/Mpc. If we expand the definition to also include galaxies with significant
total (rather than just gas) mass, i.e., those with inclination-corrected HI
line width W,cor > 500 km/s, this bring the total number of massive LSB
galaxies to 41. There are no obvious trends between the various measured global
galaxy properties, particularly between mean surface brightness and galaxy
mass.Comment: 71 pages, including all tables and figures; Accepted by A
Nonlinear optical response and spin-charge separation in one-dimensional Mott insulators
We theoretically study the nonlinear optical response and photoexcited states
of the Mott insulators. The nonlinear optical susceptibility \chi^(3) is
calculated by using the exact diagonalization technique on small clusters. From
the systematic study of the dependence of \chi^(3) on dimensionality, we find
that the spin-charge separation plays a crucial role in enhancing \chi^(3) in
the one-dimensional (1D) Mott insulators. Based on this result, we propose a
holon-doublon model, which describes the nonlinear response in the 1D Mott
insulators. These findings show that the spin-charge separation will become a
key concept of optoelectronic devices.Comment: 5 pages with 3 figures, to appear in PRB RC, 15 August 200
Zero frequency divergence and gauge phase factor in the optical response theory
The static current-current correlation leads to the definitional zero
frequency divergence (ZFD) in the optical susceptibilities. Previous
computations have shown nonequivalent results between two gauges ( and ) under the exact same unperturbed wave functions. We
reveal that those problems are caused by the improper treatment of the
time-dependent gauge phase factor in the optical response theory. The gauge
phase factor, which is conventionally ignored by the theory, is important in
solving ZFD and obtaining the equivalent results between these two gauges. The
Hamiltonians with these two gauges are not necessary equivalent unless the
gauge phase factor is properly considered in the wavefunctions. Both
Su-Shrieffer-Heeger (SSH) and Takayama-Lin-Liu-Maki (TLM) models of
trans-polyacetylene serve as our illustrative examples to study the linear
susceptibility through both current-current and dipole-dipole
correlations. Previous improper results of the calculations and
distribution functions with both gauges are discussed. The importance of gauge
phase factor to solve the ZFD problem is emphasized based on SSH and TLM
models. As a conclusion, the reason why dipole-dipole correlation favors over
current-current correlation in the practical computations is explained.Comment: 17 pages, 7 figures, submitted to Phys. Rev.
Football in the community schemes: Exploring the effectiveness of an intervention in promoting healthful behaviour change
This study aims to examine the effectiveness of a Premier League football club’s Football in the Community (FitC) schemes intervention in promoting positive healthful behaviour change in children. Specifically, exploring the effectiveness of this intervention from the perspectives of the participants involved (i.e. the researcher, teachers, children and coaches). A range of data collection techniques were utilized including the principles of ethnography (i.e. immersion, engagement and observations), alongside conducting focus groups with the children. The results allude to the intervention merely ‘keeping active children active’ via (mostly) fun, football sessions. Results highlight the important contribution the ‘coach’ plays in the effectiveness of the intervention. Results relating to working practice (i.e. coaching practice and coach recruitment) are discussed and highlighted as areas to be addressed. FitC schemes appear to require a process of positive organizational change to increase their effectiveness in strategically attending to the health agenda
Analytical solutions to the third-harmonic generation in trans-polyacetylene: Application of dipole-dipole correlation on the single electron models
The analytical solutions for the third-harmonic generation (THG) on infinite
chains in both Su-Shrieffer-Heeger (SSH) and Takayama-Lin-Liu-Maki (TLM) models
of trans-polyacetylene are obtained through the scheme of dipole-dipole ()
correlation. They are not equivalent to the results obtained through static
current-current () correlation or under polarization operator
. The van Hove singularity disappears exactly in the analytical forms,
showing that the experimentally observed two-photon absorption peak (TPA) in
THG may not be directly explained by the single electron models.Comment: 10 pages, 4 figures, submitted to Phys. Rev.
On post-Lie algebras, Lie--Butcher series and moving frames
Pre-Lie (or Vinberg) algebras arise from flat and torsion-free connections on
differential manifolds. They have been studied extensively in recent years,
both from algebraic operadic points of view and through numerous applications
in numerical analysis, control theory, stochastic differential equations and
renormalization. Butcher series are formal power series founded on pre-Lie
algebras, used in numerical analysis to study geometric properties of flows on
euclidean spaces. Motivated by the analysis of flows on manifolds and
homogeneous spaces, we investigate algebras arising from flat connections with
constant torsion, leading to the definition of post-Lie algebras, a
generalization of pre-Lie algebras. Whereas pre-Lie algebras are intimately
associated with euclidean geometry, post-Lie algebras occur naturally in the
differential geometry of homogeneous spaces, and are also closely related to
Cartan's method of moving frames. Lie--Butcher series combine Butcher series
with Lie series and are used to analyze flows on manifolds. In this paper we
show that Lie--Butcher series are founded on post-Lie algebras. The functorial
relations between post-Lie algebras and their enveloping algebras, called
D-algebras, are explored. Furthermore, we develop new formulas for computations
in free post-Lie algebras and D-algebras, based on recursions in a magma, and
we show that Lie--Butcher series are related to invariants of curves described
by moving frames.Comment: added discussion of post-Lie algebroid
Local and global modes of drug action in biochemical networks
It becomes increasingly accepted that a shift is needed from the traditional target-based approach of drug development to an integrated perspective of drug action in biochemical systems. We here present an integrative analysis of the interactions between drugs and metabolism based on the concept of drug scope. The drug scope represents the set of metabolic compounds and reactions that are potentially affected by a drug. We constructed and analyzed the scopes of all US approved drugs having metabolic targets. Our analysis shows that the distribution of drug scopes is highly uneven, and that drugs can be classified into several categories based on their scopes. Some of them have small scopes corresponding to localized action, while others have large scopes corresponding to potential large-scale systemic action. These groups are well conserved throughout different topologies of the underlying metabolic network. They can furthermore be associated to specific drug therapeutic properties
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