2,865 research outputs found
Quantum dynamics of crystals of molecular nanomagnets inside a resonant cavity
It is shown that crystals of molecular nanomagnets exhibit enhanced magnetic
relaxation when placed inside a resonant cavity. Strong dependence of the
magnetization curve on the geometry of the cavity has been observed, providing
evidence of the coherent microwave radiation by the crystals. A similar
dependence has been found for a crystal placed between Fabry-Perot
superconducting mirrors. These observations open the possibility of building a
nanomagnetic microwave laser pumped by the magnetic field
A mixed methods study of knee confidence and self-efficacy: perceptions of knee osteoarthritis patients from the good life with osteoarthritis in Denmark initiative
Purpose: The Good Life with osteoArthritis in Denmark (GLA:D) Initiative is an evidence-based treatment programme for patients with knee and hip osteoarthritis (OA). It incorporates training physiotherapists to deliver care in accordance with the clinical guidelines by educating patients on their condition and by delivering supervised neuromuscular exercises to relieve pain and improve function. The importance of self-efficacy, and confidence in exercise, to exercise adherence has not been reported for the GLA:D population. In addition, worse knee confidence in people with knee OA is associated with higher pain and greater perceived knee instability. The aims of this study were to investigate the association between knee confidence and self-efficacy in patients with knee OA in the GLA:D registry; and to explore patients’ perception of their experiences with the GLA:D programme, and whether confidence and self-efficacy has a role to play in continuing with the GLA:D exercises in the long-term.
Methods: This study used a mixed methods design. Patients with knee OA who were offered at least two educational sessions and six weeks of GLA:D exercise programme between January–March 2015 were identified from the GLA:D registry (n = 484) and sent an online survey. Ordinal regression analyses were performed. Knee confidence, assessed using the Knee injury and Osteoarthritis Outcomes Score (KOOS; quality of life subscale, question 3), was the dependent variable and self-reported measures for exercise self-efficacy; arthritis self-efficacy; multidimensional outcomes expectations for exercise; and KOOS pain and activities of daily living (ADL) were the independent variables. Knee confidence score ranged from 0–4 with 0 indicating higher knee confidence. The independent variables ranged from 0–10 or 0–100 with 0 indicating worse symptoms or confidence. Subsequently, semi-structured interviews (n = 4) were used to explore patients’ perceived confidence and adherence to the GLA:D exercises. Interviews were transcribed verbatim, and analysed using interpretative phenomenological analysis.
Results: 200 patients (41.3%) responded to the survey. At 7–10 months following treatment initiation, 9.5% of patients were not at all troubled by lack of knee confidence; 39.5% were mildly troubled; 31.5% were moderately troubled; 15.5% were severely troubled; and 4% were extremely troubled. Patients with higher arthritis self-efficacy score were more likely to have higher knee confidence (odds ratio [OR] = 0.76; 95% confidence interval [CI] 0.63, 0.93; P = 0.007). Patients with higher KOOS ADL score were more likely to have higher knee confidence, although this association was small (OR = 0.96; 95% CI 0.93, 0.99; P = 0.006). No association was found between knee confidence and exercise self-efficacy (OR = 1.00; 95% CI 0.99, 1.01; P = 0.90). Patients reflected on seeing great improvements in their confidence, pain and mobility with the programme. They felt their symptoms got worse if they did not keep up with the exercises. Patients reflected on the importance of continued contact with their physiotherapist after the 6-week programme for further motivation and reassurance. One of the barriers that discouraged patients from continuing with the exercises in the long-term was the cost for additional GLA:D exercise classes with their physiotherapist.
Conclusions: Patients are troubled by the lack of knee confidence after the GLA:D exercise programme; they reflected this was due to their negative experiences prior to entering the GLA:D programme. Arthritis self-efficacy and KOOS ADL were significantly associated with knee confidence, but no association was found with exercise self-efficacy. Patients from the interview reflected that maintaining contact with their physiotherapist was an important factor to motivate them to continue exercising
Partially Ordered Two-way B\"uchi Automata
We introduce partially ordered two-way B\"uchi automata and characterize
their expressive power in terms of fragments of first-order logic FO[<].
Partially ordered two-way B\"uchi automata are B\"uchi automata which can
change the direction in which the input is processed with the constraint that
whenever a state is left, it is never re-entered again. Nondeterministic
partially ordered two-way B\"uchi automata coincide with the first-order
fragment Sigma2. Our main contribution is that deterministic partially ordered
two-way B\"uchi automata are expressively complete for the first-order fragment
Delta2. As an intermediate step, we show that deterministic partially ordered
two-way B\"uchi automata are effectively closed under Boolean operations.
A small model property yields coNP-completeness of the emptiness problem and
the inclusion problem for deterministic partially ordered two-way B\"uchi
automata.Comment: The results of this paper were presented at CIAA 2010; University of
Stuttgart, Computer Scienc
Tropical surface singularities
In this paper, we study tropicalisations of singular surfaces in toric
threefolds. We completely classify singular tropical surfaces of
maximal-dimensional type, show that they can generically have only finitely
many singular points, and describe all possible locations of singular points.
More precisely, we show that singular points must be either vertices, or
generalized midpoints and baricenters of certain faces of singular tropical
surfaces, and, in some cases, there may be additional metric restrictions to
faces of singular tropical surfaces.Comment: A gap in the classification was closed. 37 pages, 29 figure
Application of regulatory sequence analysis and metabolic network analysis to the interpretation of gene expression data
We present two complementary approaches for the interpretation of clusters of
co-regulated genes, such as those obtained from DNA chips and related methods.
Starting from a cluster of genes with similar expression profiles, two basic
questions can be asked:
1. Which mechanism is responsible for the coordinated transcriptional response
of the genes? This question is approached by extracting motifs that are shared
between the upstream sequences of these genes. The motifs extracted are putative
cis-acting regulatory elements.
2. What is the physiological meaning for the cell to express together these
genes? One way to answer the question is to search for potential metabolic
pathways that could be catalyzed by the products of the genes. This can be
done by selecting the genes from the cluster that code for enzymes, and trying
to assemble the catalyzed reactions to form metabolic pathways.
We present tools to answer these two questions, and we illustrate their use with
selected examples in the yeast Saccharomyces cerevisiae. The tools are available
on the web (http://ucmb.ulb.ac.be/bioinformatics/rsa-tools/;
http://www.ebi.ac.uk/research/pfbp/; http://www.soi.city.ac.uk/~msch/)
Dislocation-induced spin tunneling in Mn-12 acetate
Comprehensive theory of quantum spin relaxation in Mn-12 acetate crystals is
developed, that takes into account imperfections of the crystal structure and
is based upon the generalization of the Landau-Zener effect for incoherent
tunneling from excited energy levels. It is shown that linear dislocations at
plausible concentrations provide the transverse anisotropy which is the main
source of tunneling in Mn-12. Local rotations of the easy axis due to
dislocations result in a transverse magnetic field generated by the field
applied along the c-axis of the crystal, which explains the presence of odd
tunneling resonances. Long-range deformations due to dislocations produce a
broad distribution of tunnel splittings. The theory predicts that at subkelvin
temperatures the relaxation curves for different tunneling resonances can be
scaled onto a single master curve. The magnetic relaxation in the thermally
activated regime follows the stretched-exponential law with the exponent
depending on the field, temperature, and concentration of defects.Comment: 17 pages, 14 figures, 1 table, submitted to PR
A within farm clinical trial to compare two treatments (parenteral antibacterials and hoof trimming) for sheep lame with footrot
From observational studies, farmers who use parenteral antibacterials to promptly treat all sheep with footrot (FR) or interdigital dermatitis (ID) have a prevalence of lameness of <2% compared with a prevalence of 9% lameness reported by farmers who treat lame sheep by trimming affected feet. We tested the hypothesis that prompt treatment of sheep lame with naturally developing FR or ID with parenteral and topical antibacterials reduces the prevalence and incidence of lameness with these conditions compared with less frequent treatment with trimming of hoof horn and applying topical antibacterials. A further hypothesis was that reduction of ID and FR would improve productivity. A lowland sheep flock with 700 ewes was used to test these hypotheses in an 18-month within farm clinical trial with four groups of ewes: two intervention and two control. The duration and severity of lameness was used to categorise sheep into three weighted scores of lameness (WLS): never lame (WLS0), mildly lame/lame for <6 days (WLS1) and severely or chronically lame (WLS2). The intervention reduced the prevalence of lameness due to FR and ID in ewes and lambs and the incidence of lameness in ewes. The WLS was also significantly lower in sheep in the intervention groups. Ewes with a higher WLS were subsequently significantly more likely to have a body condition score <2.5 and to have lame lambs. Significantly more ewes lambed and successfully reared more lambs that were ready for slaughter at a younger age in the intervention versus control groups. There was an increase in the gross margin of £630/100 ewes mated in the intervention group, including the cost of treatment of £150/100 ewes mated. We conclude that prompt parenteral and topical antibacterial treatment of sheep lame with ID and FR reduced the prevalence and incidence of these infectious conditions and led to improved health, welfare and productivity
Oscillation of the tunnel splitting in nanospin systems within the particle mapping formalism
The oscillation of tunnel splitting in the biaxial spin system within
magnetic field along the anisotropy axis is analyzed within the particle
mapping approach, rather than in the (\theta-\phi) spin coherent-state
representation. In our mapping procedure, the spin system is transformed into a
particle moving in the restricted geometry whose wave function subjects
to the boundary condition involving additional phase shift. We obtain the new
topological phase that plays the same role as the Wess-Zumino action in spin
coherent-state representation. Considering the interference of two possible
trajectories, instanton and anti-instanton, we get the identical condition for
the field at which tunneling is quenched, with the previous result within spin
coherent-state representation.Comment: 11 pages, 1 figure; Some typographical errors have been correcte
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