347 research outputs found
The C*-algebra of an affine map on the 3-torus
We study the C*-algebra of an affine map on a compact abelian group and give
necessary and sufficient conditions for strong transitivity when the group is a
torus. The structure of the C*-algebra is completely determined for all
strongly transitive affine maps on a torus of dimension one, two or three
The Effect on Selenium Concentrations of a Randomized Intervention with Fish and Mussels in a Population with Relatively Low Habitual Dietary Selenium Intake
Selenium status of the Danish population is below that assumed optimal for the suggested protective effects against chronic diseases, including certain cancers. Fish and shellfish are important dietary sources of selenium in Denmark. We investigated the effect of increased fish and mussel intake on selenium blood concentrations in a population with relatively low habitual dietary selenium intake. We randomly assigned 102 healthy men and women (all non-smokers) aged 48–76 years to an intervention group (n = 51) or a control group (n = 51). Intervention participants received 1000 g fish and mussels/week for 26 weeks (~50 μg selenium/day). Controls received no intervention. Non-fasting blood samples were taken and whole blood selenium was determined using inductively coupled plasma-mass spectrometry (ICP-MS), and plasma selenoprotein P (SelP) was determined by high performance liquid chromatography coupled to ICP-MS. All available observations were included in linear multiple regression analysis to evaluate the effect of the intervention. The difference in mean change for intervention compared with control persons was 14.9 ng/mL (95% CI: 10.2, 19.7) for whole blood selenium, and 7.0 ng/mL (95% CI: 3.1, 10.9) for plasma SelP (Weeks 0–26). Selenium concentrations were significantly increased after 26 weeks of intervention, albeit to a lower degree than expected
Linking Dynamical and Thermal Models of Ultrarelativistic Nuclear Scattering
To analyse ultrarelativistic nuclear interactions, usually either dynamical
models like the string model are employed, or a thermal treatment based on
hadrons or quarks is applied. String models encounter problems due to high
string densities, thermal approaches are too simplistic considering only
average distributions, ignoring fluctuations. We propose a completely new
approach, providing a link between the two treatments, and avoiding their main
shortcomings: based on the string model, connected regions of high energy
density are identified for single events, such regions referred to as quark
matter droplets. Each individual droplet hadronizes instantaneously according
to the available n-body phase space. Due to the huge number of possible hadron
configurations, special Monte Carlo techniques have been developed to calculate
this disintegration.Comment: Complete paper enclosed as postscript file (uuencoded
Microcanonical Treatment of Hadronizing the Quark-Gluon Plasma
We recently introduced a completely new way to study ultrarelativistic
nuclear scattering by providing a link between the string model approach and a
statistical description. A key issue is the microcanonical treatment of
hadronizing individual quark matter droplets. In this paper we describe in
detail the hadronization of these droplets according to n-body phase space, by
using methods of statistical physics, i.e. constructing Markov chains of hadron
configurations.Comment: Complete paper enclosed as postscript file (uuencoded
Prevalence and anatomical location of muscle tenderness in adults with nonspecific neck/shoulder pain
<p>Abstract</p> <p>Background</p> <p>Many adults experience bothersome neck/shoulder pain. While research and treatment strategies often focus on the upper trapezius, other neck/shoulder muscles may be affected as well. The aim of the present study is to evaluate the prevalence and anatomical location of muscle tenderness in adults with nonspecific neck/shoulder pain.</p> <p>Methods</p> <p>Clinical neck/shoulder examination at two large office workplaces in Copenhagen, Denmark. 174 women and 24 men (aged 25-65 years) with nonspecific neck/shoulder pain for a duration of at least 30 days during the previous year and a pain intensity of at least 2 on a modified VAS-scale of 0-10 participated. Exclusion criteria were traumatic injuries or other serious chronic disease. Using a standardized finger pressure of 2 kg, palpable tenderness were performed of eight anatomical neck/shoulder locations in the left and right side on a scale of 'no tenderness', 'some tenderness' and 'severe tenderness'.</p> <p>Results</p> <p>In women, the levator scapulae, neck extensors and infraspinatus showed the highest prevalence of severe tenderness (18-30%). In comparison, the prevalence of severe tenderness in the upper trapezius, occipital border and supraspinatus was 13-19%. Severe tenderness of the medial deltoid was least prevalent (0-1%). In men, the prevalence of severe tenderness in the levator scapulae was 13-21%, and ranged between 0-8% in the remainder of the examined anatomical locations.</p> <p>Conclusions</p> <p>A high prevalence of tenderness exists in several anatomical locations of the neck/shoulder complex among adults with nonspecific neck/shoulder pain. Future research should focus on several neck/shoulder muscles, including the levator scapulae, neck extensors and infraspinatus, and not only the upper trapezius.</p> <p>Trial Registration</p> <p><a href="http://www.controlled-trials.com/ISRCTN60264809">ISRCTN60264809</a></p
A Growth Curve Model with Fractional Polynomials for Analysing Incomplete Time-Course Data in Microarray Gene Expression Studies
Identifying the various gene expression response patterns is a challenging issue in expression microarray time-course experiments. Due to heterogeneity in the regulatory reaction among thousands of genes tested, it is impossible to manually characterize a parametric form for each of the time-course pattern in a gene by gene manner. We introduce a growth curve model with fractional polynomials to automatically capture the various time-dependent expression patterns and meanwhile efficiently handle missing values due to incomplete observations. For each gene, our procedure compares the performances among fractional polynomial models with power terms from a set of fixed values that offer a wide range of curve shapes and suggests a best fitting model. After a limited simulation study, the model has been applied to our human in vivo irritated epidermis data with missing observations to investigate time-dependent transcriptional responses to a chemical irritant. Our method was able to identify the various nonlinear time-course expression trajectories. The integration of growth curves with fractional polynomials provides a flexible way to model different time-course patterns together with model selection and significant gene identification strategies that can be applied in microarray-based time-course gene expression experiments with missing observations
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