7,098 research outputs found
AMK: An Interface For Object-oriented Newtonian Particle Mechanics
This article describes an object-oriented environment with an associated
user interface, AMK, for modelling simple Newtonian particle mechanics. It is
intended for educational use, and provides a framework for modelling which
generalises methodology. Physical objects are treated as logical objects, and
mathematical models are formulated by linking them. The implementation is
within the Windows environment using Mathematica and Visual Basic. Modelling
is done by constructing objects and linking them to produce new objects. The
aim is to produce an equation of motion object. The interface forces the user into
a modelling cycle of constructing and linking objects, and accessing their
methods. It constructs a Mathematica input automatically from information
supplied by the user, and communicates with Mathematica. The combination of
a generalised environment plus interface produces correct answers when modelling
many specific physical systems
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Resonances in coupled πk,ηK scattering from lattice QCD
Coupled-channel and scattering amplitudes are determined by
studying the finite-volume energy spectra obtained from dynamical lattice QCD
calculations. Using a large basis of interpolating operators, including both
those resembling a construction and those resembling a pair of
mesons with relative momentum, a reliable excited-state spectrum can be
obtained. Working at , we find a gradual increase in
the phase-shift which may be identified with a broad scalar
resonance that couples strongly to and weakly to . The
low-energy behavior of this amplitude suggests a virtual bound-state that may
be related to the resonance. A bound state with is found
very close to the threshold energy, whose coupling to the
channel is compatible with that of the experimental . Evidence is
found for a narrow resonance in . Isospin--3/2 scattering is
also studied and non-resonant phase-shifts spanning the whole elastic
scattering region are obtained.We thank our colleagues within the Hadron Spectrum
Collaboration. We also thank R. Briceno, M.R. Pennington,
C.J.Shultz and A.P. Szczepaniak for fruitful discussions.
Chroma [63] and QUDA [64, 65] were used to perform
this work on clusters at Jefferson Laboratory under the
USQCD Initiative and the LQCD ARRA project. Gauge
configurations were generated using resources awarded
from the U.S. Department of Energy INCITE program
at Oak Ridge National Lab, the NSF Teragrid at the
Texas Advanced Computer Center and the Pittsburgh
Supercomputer Center, as well as at Jefferson Lab. RGE
and JJD acknowledge support from U.S. Department of
Energy contract DE-AC05-06OR23177, under which Jefferson
Science Associates, LLC, manages and operates
Jefferson Laboratory. JJD acknowledges support from
the U.S. Department of Energy Early Career award contract
DE-SC0006765. CET acknowledges partial support
from the Science and Technology Facilities Council
(U.K.) [grant number ST/L000385/1].This is the accepted manuscript. The final version is available at http://journals.aps.org/prd/abstract/10.1103/PhysRevD.91.054008
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B1 resonance in coupled πω, πφ scattering from lattice QCD
We present the first lattice QCD calculation of coupled and
scattering, incorporating coupled and -wave in
. Finite-volume spectra in three volumes are determined via a
variational analysis of matrices of two-point correlation functions, computed
using large bases of operators resembling single-meson, two-meson and
three-meson structures, with the light-quark mass corresponding to a pion mass
of MeV. Utilizing the relationship between the discrete
spectrum of finite-volume energies and infinite-volume scattering amplitudes,
we find a narrow axial-vector resonance (), the analogue of the
meson, with mass MeV and width
MeV. The resonance is found to couple dominantly to -wave , with
a much-suppressed coupling to -wave , and a negligible coupling
to consistent with the `OZI rule'. No resonant behavior is observed
in , indicating the absence of a putative low-mass analogue of
the claimed in . In order to minimally present the contents
of a unitary three-channel scattering matrix, we introduce an -channel
generalization of the traditional two-channel Stapp parameterization
Decays of an exotic 1-+ hybrid meson resonance in QCD
We present the first determination of the hadronic decays of the lightest
exotic resonance in lattice QCD. Working with SU(3) flavor
symmetry, where the up, down and strange quark masses approximately match the
physical strange-quark mass giving MeV, we compute
finite-volume spectra on six lattice volumes which constrain a scattering
system featuring eight coupled channels. Analytically continuing the scattering
amplitudes into the complex energy plane, we find a pole singularity
corresponding to a narrow resonance which shows relatively weak coupling to the
open pseudoscalar--pseudoscalar, vector--pseudoscalar and vector--vector decay
channels, but large couplings to at least one kinematically-closed
axial-vector--pseudoscalar channel. Attempting a simple extrapolation of the
couplings to physical light-quark mass suggests a broad resonance
decaying dominantly through the mode with much smaller decays into
, , and . A large total width is
potentially in agreement with the experimental candidate state,
observed in , , which we suggest may be heavily suppressed
decay channels
The process of establishing implementing and maintaining a social support infant feeding programme
Objective To describe the process of establishing and implementing a social support infant feeding intervention.
Design This paper outlines the initial stages of a randomised controlled trial which assessed the effectiveness of a social support intervention on a range of infant feeding outcomes. Details are presented of the processes involved in recruiting, training and supporting a group of volunteers who provided support to the study sample.
Setting Camden and Islington, London, UK.
Results Initial networking with local agencies and organisations provided invaluable information and contacts. Employing a dedicated volunteer co-ordinator is vitally important in the recruitment, training and support of volunteers. Providing child care and travel expenses is an essential incentive for volunteers with young children. Advertisements placed in local newspapers were the most successful means of recruiting volunteers. Appropriate training is needed to equip volunteers with the necessary knowledge and skills to provide effective support. Particular emphasis in the training focused upon developing the necessary interpersonal skills and self-confidence. The evaluation of the training programme demonstrated that it improved volunteers’ knowledge and reported confidence. The provision of ongoing support is also essential to maintain volunteers’ interest and enthusiasm. The retention of volunteers is, however, a key challenge.
Conclusions The processes outlined in this paper have demonstrated the feasibility of successfully establishing, implementing and maintaining a community-based social support infant feeding programme. The experiences described provide useful insights into the practical issues that need to be addressed in setting up a social support intervention
Photosynthetic activity and population dynamics of Amoebobacter purpureus in a meromictic saline lake
Abstract A dense population of the purple sulfur bacterium Amoebobacter purpureus in the chemocline of meromictic Mahoney Lake (British Columbia, Canada) underwent consistent changes in biomass over a two year study period. The integrated amount of bacteriochlorophyll reached maxima in August and declined markedly during early fall. Bacteriochlorophyll was only weakly correlated with the light intensity and water temperature in the chemocline. In the summer, bacterial photosynthesis was limited by sulfide availability. During this period the intracellular sulfur concentration of A. purpureus cells decreased. A minimum concentration was measured at the top of the bacterial layer in August, when specific photosynthetic rates of A. purpureus indicated that only 14% of the cells were photosynthetically active. With the exception of a time period between August and September, the specific growth rates calculated from CO2 fixation rates of A. purpureus were similar to growth rates calculated from actual biomass changes in the bacterial layer. Between August and September 86% of the A. purpureus biomass disappeared from the chemocline and were deposited on the littoral sediment of Mahoney Lake or degraded within the mixolimnion. This rise of cells to the lake surface was not mediated by an increase in the specific gas vesicle content which remained constant between April and November. The upwelling phenomenon was related to the low sulfur content of A. purpureus cells and a low resistance of surface water layers against vertical mixing by wind
The early inflorescence of Arabidopsis thaliana demonstrates positional effects in floral organ growth and meristem patterning.
Linear modelling approaches detected significant gradients in organ growth and patterning across early flowers of the Arabidopsis inflorescence and uncovered evidence of new roles for gibberellin in floral development. Most flowering plants, including the genetic model Arabidopsis thaliana, produce multiple flowers in sequence from a reproductive shoot apex to form a flower spike (inflorescence). The development of individual flowers on an Arabidopsis inflorescence has typically been considered as highly stereotypical and uniform, but this assumption is contradicted by the existence of mutants with phenotypes visible in early flowers only. This phenomenon is demonstrated by mutants partially impaired in the biosynthesis of the phytohormone gibberellin (GA), in which floral organ growth is retarded in the first flowers to be produced but has recovered spontaneously by the 10th flower. We presently lack systematic data from multiple flowers across the Arabidopsis inflorescence to explain such changes. Using mutants of the GA 20-OXIDASE (GA20ox) GA biosynthesis gene family to manipulate endogenous GA levels, we investigated the dynamics of changing floral organ growth across the early Arabidopsis inflorescence (flowers 1-10). Modelling of floral organ lengths identified a significant, GA-independent gradient of increasing stamen length relative to the pistil in the wild-type inflorescence that was separable from other, GA-dependent effects. It was also found that the first flowers exhibited unstable organ patterning in contrast to later flowers and that this instability was prolonged by exogenous GA treatment. These findings indicate that the development of individual flowers is influenced by hitherto unknown factors acting across the inflorescence and also suggest novel functions for GA in floral patterning
Evaluation of an Activated Patient Diabetes Education Newsletter
This study evaluated a monthly; activated patient newsletter sent to over 7000 patients in Michigan with diabetes. The newsletter provided concise and action-oriented information about diabetes care. Patients who had signed up to receive the newsletter during the first 4 months of the project (1863) were surveyed to determine how many patients found the newsletter helpful; 80% (1498) of the patients replied. Patients who found the newsletter most helpful were older, had lower incomes, and reported more corrtplications, less understanding of diabetes, and being in poorer overall health. They also were more likely to have non-insulin-dependent diabetes mellitus (NIDDM) than insulin-dependent diabetes mellitus (IDDM). We concluded that the activated patient newsletter is a useful public health/patient education intervention for persons with diabetes. Such a newsletter should be part of a coordinated system of ongoing patient care, education, screening, and social and psychological support.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68904/2/10.1177_014572179402000106.pd
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