7,087 research outputs found
Fermion Helicity Flip Induced by Torsion Field
We show that in theories of gravitation with torsion the helicity of fermion
particles is not conserved and we calculate the probability of spin flip, which
is related to the anti-symmetric part of affine connection. Some cosmological
consequences are discussed.Comment: 6 pages, to appear in Europhysics Letter
Lifetime measurements of Triaxial Strongly Deformed bands in Tm
With the Doppler Shift Attenuation Method, quadrupole transition moments,
, were determined for the two recently proposed Triaxial Strongly Deformed
(TSD) bands in Tm. The measured moments indicate that the
deformation of these bands is larger than that of the yrast, signature
partners. However, the measured values are smaller than those predicted by
theory. This observation appears to be valid for TSD bands in several nuclei of
the regionComment: 8 pages, 5 figures. Submitted to Physical Review
Riemannian and Teleparallel Descriptions of the Scalar Field Gravitational Interaction
A comparative study between the metric and the teleparallel descriptions of
gravitation is made for the case of a scalar field. In contrast to the current
belief that only spin matter could detect the teleparallel geometry, scalar
matter being able to feel the metric geometry only, we show that a scalar field
is able not only to feel anyone of these geometries, but also to produce
torsion. Furthermore, both descriptions are found to be completely equivalent,
which means that in fact, besides coupling to curvature, a scalar field couples
also to torsion.Comment: Minor corrections made, and a paragraph added to the last section.
Version to appear in Gen. Rel. Gra
Investigation of mechanical losses of thin silicon flexures at low temperatures
The investigation of the mechanical loss of different silicon flexures in a
temperature region from 5 to 300 K is presented. The flexures have been
prepared by different fabrication techniques. A lowest mechanical loss of
was observed for a 130 m thick flexure at around 10 K.
While the mechanical loss follows the thermoelastic predictions down to 50 K a
difference can be observed at lower temperatures for different surface
treatments. This surface loss will be limiting for all applications using
silicon based oscillators at low temperatures. The extraction of a surface loss
parameter using different results from our measurements and other references is
presented. We focused on structures that are relevant for gravitational wave
detectors. The surface loss parameter = 0.5 pm was obtained. This
reveals that the surface loss of silicon is significantly lower than the
surface loss of fused silica.Comment: 16 pages, 7 figure
Foot health education for people with rheumatoid arthritis : the practitioner's perspective
Background: Patient education is considered to be a key role for podiatrists in the management of patients with rheumatoid arthritis (RA). Patient education has undoubtedly led to improved clinical outcomes, however no attempts have been made to optimise its content or delivery to maximise benefits within the context of the foot affected by rheumatoid arthritis. The aim of this study was to identify the nature and content of podiatrists' foot health education for people with RA. Any potential barriers to its provision were also explored.
Methods: A focus group was conducted. The audio dialogue was recorded digitally, transcribed verbatim and analysed using a structured, thematic approach. The full transcription was verified by the focus group as an accurate account of what was said. The thematic analysis framework was verified by members of the research team to ensure validity of the data.
Results: Twelve members (all female) of the north west Podiatry Clinical Effectiveness Group for Rheumatology participated. Six overarching themes emerged: (i) the essence of patient education; (ii) the content; (iii) patient-centred approach to content and timing; (iv) barriers to provision; (v) the therapeutic relationship; and (vi) tools of the trade.
Conclusion: The study identified aspects of patient education that this group of podiatrists consider most important in relation to its: content, timing, delivery and barriers to its provision. General disease and foot health information in relation to RA together with a potential prognosis for foot health, the role of the podiatrist in management of foot health, and appropriate self-management strategies were considered to be key aspects of content, delivered according to the needs of the individual. Barriers to foot health education provision, including financial constraints and difficulties in establishing effective therapeutic relationships, were viewed as factors that strongly influenced foot health education provision. These data will contribute to the development of a patient-centred, negotiated approach to the provision of foot health education for people with RA
Cmah-dystrophin deficient mdx mice display an accelerated cardiac phenotype that is improved following peptide-PMO exon skipping treatment
Duchenne muscular dystrophy (DMD) is caused by loss of dystrophin protein, leading to progressive muscle weakness and premature death due to respiratory and/or cardiac complications. Cardiac involvement is characterized by progressive dilated cardiomyopathy, decreased fractional shortening and metabolic dysfunction involving reduced metabolism of fatty acidsâthe major cardiac metabolic substrate. Several mouse models have been developed to study molecular and pathological consequences of dystrophin deficiency, but do not recapitulate all aspects of human disease pathology and exhibit a mild cardiac phenotype. Here we demonstrate that Cmah (cytidine monophosphate-sialic acid hydroxylase)-deficient mdx mice (Cmahâ/â;mdx) have an accelerated cardiac phenotype compared to the established mdx model. Cmahâ/â;mdx mice display earlier functional deterioration, specifically a reduction in right ventricle (RV) ejection fraction and stroke volume (SV) at 12 weeks of age and decreased left ventricle diastolic volume with subsequent reduced SV compared to mdx mice by 24 weeks. They further show earlier elevation of cardiac damage markers for fibrosis (Ctgf), oxidative damage (Nox4) and haemodynamic load (Nppa). Cardiac metabolic substrate requirement was assessed using hyperpolarized magnetic resonance spectroscopy indicating increased in vivo glycolytic flux in Cmahâ/â;mdx mice. Early upregulation of mitochondrial genes (Ucp3 and Cpt1) and downregulation of key glycolytic genes (Pdk1, Pdk4, Ppara), also denote disturbed cardiac metabolism and shift towards glucose utilization in Cmahâ/â;mdx mice. Moreover, we show long-term treatment with peptide-conjugated exon skipping antisense oligonucleotides (20-week regimen), resulted in 20% cardiac dystrophin protein restoration and significantly improved RV cardiac function. Therefore, Cmahâ/â;mdx mice represent an appropriate model for evaluating cardiac benefit of novel DMD therapeutics
Hestenes' Tetrad and Spin Connections
Defining a spin connection is necessary for formulating Dirac's bispinor
equation in a curved space-time. Hestenes has shown that a bispinor field is
equivalent to an orthonormal tetrad of vector fields together with a complex
scalar field. In this paper, we show that using Hestenes' tetrad for the spin
connection in a Riemannian space-time leads to a Yang-Mills formulation of the
Dirac Lagrangian in which the bispinor field is mapped to a set of Yang-Mills
gauge potentials and a complex scalar field. This result was previously proved
for a Minkowski space-time using Fierz identities. As an application we derive
several different non-Riemannian spin connections found in the literature
directly from an arbitrary linear connection acting on Hestenes' tetrad and
scalar fields. We also derive spin connections for which Dirac's bispinor
equation is form invariant. Previous work has not considered form invariance of
the Dirac equation as a criterion for defining a general spin connection
Design of a speed meter interferometer proof-of-principle experiment
The second generation of large scale interferometric gravitational wave
detectors will be limited by quantum noise over a wide frequency range in their
detection band. Further sensitivity improvements for future upgrades or new
detectors beyond the second generation motivate the development of measurement
schemes to mitigate the impact of quantum noise in these instruments. Two
strands of development are being pursued to reach this goal, focusing both on
modifications of the well-established Michelson detector configuration and
development of different detector topologies. In this paper, we present the
design of the world's first Sagnac speed meter interferometer which is
currently being constructed at the University of Glasgow. With this
proof-of-principle experiment we aim to demonstrate the theoretically predicted
lower quantum noise in a Sagnac interferometer compared to an equivalent
Michelson interferometer, to qualify Sagnac speed meters for further research
towards an implementation in a future generation large scale gravitational wave
detector, such as the planned Einstein Telescope observatory.Comment: Revised version: 16 pages, 6 figure
Charging Interacting Rotating Black Holes in Heterotic String Theory
We present a formulation of the stationary bosonic string sector of the whole
toroidally compactified effective field theory of the heterotic string as a
double Ernst system which, in the framework of General Relativity describes, in
particular, a pair of interacting spinning black holes; however, in the
framework of low--energy string theory the double Ernst system can be
particularly interpreted as the rotating field configuration of two interacting
sources of black hole type coupled to dilaton and Kalb--Ramond fields. We
clarify the rotating character of the --component of the
antisymmetric tensor field of Kalb--Ramond and discuss on its possible torsion
nature. We also recall the fact that the double Ernst system possesses a
discrete symmetry which is used to relate physically different string vacua.
Therefore we apply the normalized Harrison transformation (a charging symmetry
which acts on the target space of the low--energy heterotic string theory
preserving the asymptotics of the transformed fields and endowing them with
multiple electromagnetic charges) on a generic solution of the double Ernst
system and compute the generated field configurations for the 4D effective
field theory of the heterotic string. This transformation generates the
vector field content of the whole low--energy heterotic string
spectrum and gives rise to a pair of interacting rotating black holes endowed
with dilaton, Kalb--Ramond and multiple electromagnetic fields where the charge
vectors are orthogonal to each other.Comment: 15 pages in latex, revised versio
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