3,988 research outputs found
A Simple Method for Computing Singular or Nearly Singular Integrals on Closed Surfaces
We present a simple, accurate method for computing singular or nearly
singular integrals on a smooth, closed surface, such as layer potentials for
harmonic functions evaluated at points on or near the surface. The integral is
computed with a regularized kernel and corrections are added for regularization
and discretization, which are found from analysis near the singular point. The
surface integrals are computed from a new quadrature rule using surface points
which project onto grid points in coordinate planes. The method does not
require coordinate charts on the surface or special treatment of the
singularity other than the corrections. The accuracy is about , where
is the spacing in the background grid, uniformly with respect to the point
of evaluation, on or near the surface. Improved accuracy is obtained for points
on the surface. The treecode of Duan and Krasny for Ewald summation is used to
perform sums. Numerical examples are presented with a variety of surfaces.Comment: to appear in Commun. Comput. Phy
Oxygen Cost of Recreational Horse-Riding in Females
Version: as accepted for publication.BACKGROUND: The purpose of this study was to characterize the physiological demands of a riding session comprising different types of recreational horse riding in females. METHODS: Sixteen female recreational riders (aged 17 to 54 years) completed an incremental cycle ergometer exercise test to determine peak oxygen consumption (VOâpeak) and a 45-minute riding session based upon a British Horse Society Stage 2 riding lesson (including walking, trotting, cantering and work without stirrups). Oxygen consumption (VOâ), from which metabolic equivalent (MET) and energy expenditure values were derived, was measured throughout. RESULTS: The mean VOâ requirement for trotting/cantering (18.4 ± 5.1 ml·kgâ»Âč·minâ»Âč; 52 ± 12% VOâpeak; 5.3 ± 1.1 METs) was similar to walking/trotting (17.4 ± 5.1 ml·kgâ»Âč·minâ»Âč; 48 ± 13% VOâpeak; 5.0 ± 1.5 METs) and significantly higher than for work without stirrups (14.2 ± 2.9 ml·kgâ»Âč·minâ»Âč; 41 ± 12% VOâpeak; 4.2 ± 0.8 METs) (P = .001). CONCLUSIONS: The oxygen cost of different activities typically performed in a recreational horse riding session meets the criteria for moderate intensity exercise (3-6 METs) in females, and trotting combined with cantering imposes the highest metabolic demand. Regular riding could contribute to the achievement of the public health recommendations for physical activity in this population
Hot methane line lists for exoplanet and brown dwarf atmospheres
We present comprehensive experimental line lists of methane (CH4) at high
temperatures obtained by recording Fourier transform infrared emission spectra.
Calibrated line lists are presented for the temperatures 300 - 1400 degC at
twelve 100 degC intervals spanning the 960 - 5000 cm-1 (2.0 - 10.4 microns)
region of the infrared. This range encompasses the dyad, pentad and octad
regions, i.e., all fundamental vibrational modes along with a number of
combination, overtone and hot bands. Using our CH4 spectra, we have estimated
empirical lower state energies (Elow in cm-1) and our values have been
incorporated into the line lists along with line positions (cm-1) and
calibrated line intensities (S' in cm molecule-1). We expect our hot CH4 line
lists to find direct application in the modeling of planetary atmospheres and
brown dwarfs.Comment: Supplementary material is provided via the Astrophysical Journal
referenc
Dynamic stability of a uniform free-free beam under a gimbaled thrust of periodically varying magnitude
Dynamic stability of bending vibrations of uniform free-free beam under end thrust with application to rocket vehicle
A Qualitative Investigation Into the Impact of the Basketball Learning Intervention Programme (BLIP) on Disengaged Secondary School Students in the United Kingdom
This paper will evaluate the longitudinal effects of a basketball based intervention programme that targeted ten disengaged male secondary school students at a school in the Kent, England. The programme aimed to improve the behaviour and academic performance of the participants through a weekly intervention carried out by an external basketball player and coach providing academic support, mentoring and specially designed basketball sessions.
Sports interventions have been deemed to provide a positive short-term impact on young people. However, researchers have identified the need for a longitudinal approach in order to examine the effects of such interventions post involvement as supported.
This study involved five former Basketball Learning Intervention Programme (BLIP) members (with a mean age of 16.4 SD± 0.55 years) that were interviewed using semi-structured interview approach, 12 months after completing the intervention.
Interpretative Phenomenological Analysis (IPA) revealed four superordinate and eleven subordinate themes. The four superordinate themes were; âbaseline behaviours pre-interventionâ, âimmediate outcomes of the BLIPâ, âimpact of the coachâ and âlong standing transferable outcomesâ.
The results revealed an immediate impact in comparison to the baseline behaviours of the participants pre-intervention. The data suggested that one of the most effective aspects of the programme was the positive impact of the coach on the participants. More importantly, this is the only study to report long-term improvements amongst the participants
in terms of behaviour and academics as a result of engagement in a sports based intervention
Identifying Archetypal Perspectives in News Articles.
A novel approach to news aggregation is proposed. Rather than ranking or summarisation of cluster topics, we propose that articles are grouped by topic similarity and then clustered within topic groups in order to identify archetypal articles that represent the various perspectives upon a topic. An example application is examined and a preliminary user study is discussed. Future applications and evaluation of validity are outlined
The Design of the Pallet Program
This paper describes the procedures underlying the development of the Pallet program which has been produced to design regular pallet racks according to the FEM code. The program determines the buckling load of the equivalent free sway structure and, using stability functions, calculates the axial and shear forces and the bending moments within the structure including the non-linear P - Ăâ effects. Twelve different combinations of load are analysed and design checks given in the FEM code applied. The paper discusses the different modes of operation of the program. Finally the accuracy of the program is discussed together with future developments
Production of methanol acetaldehyde and acetone in the Atlantic Ocean
The biogeochemistry of oxygenated volatile organic compounds (OVOCs) like methanol, acetaldehyde, and acetone in marine waters is poorly understood. We report the first in situ gross production rates for methanol, acetaldehyde, and acetone of 49â103, 25â98, and 2â26ânmolâLâ1âdâ1 over contrasting areas of marine productivity, including oligotrophic gyres and eutrophic upwellings. Photochemical production estimates are mostly negligible for methanol, up to 68% for acetaldehyde and up to 100% of gross production rates for acetone. Microbial surface OVOC oxidation to CO2 accounts for between 10â50% and 0.5â13% of the methanol and acetone losses, respectively, but largely control acetaldehyde concentrations (49â100%). Biological lifetimes in a coastal upwelling vary between â€1âday for acetaldehyde, to approximately 7âdays for methanol and up to ~80âdays for acetone. In open oceanic environments, the lifetime of acetaldehyde ranges between 2 and 5âh, compared to 10â26âdays for methanol and 5â55âdays for acetone
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