428 research outputs found
Non-metric chaotic inflation
We consider inflation within the context of what is arguably the simplest
non-metric extension of Einstein gravity. There non-metricity is described by a
single graviscalar field with a non-minimal kinetic coupling to the inflaton
field , parameterized by a single parameter . We discuss the
implications of non-metricity for chaotic inflation and find that it
significantly alters the inflaton dynamics for field values , dramatically changing the qualitative behaviour in this regime.
For potentials with a positive slope non-metricity imposes an upper bound on
the possible number of e-folds. For chaotic inflation with a monomial
potential, the spectral index and the tensor-to-scalar ratio receive small
corrections dependent on the non-metricity parameter. We also argue that
significant post-inflationary non-metricity may be generated.Comment: 7 pages, 1 figur
An Einstein-Hilbert Action for Axi-Dilaton Gravity in 4-Dimensions
We examine the axi-dilatonic sector of low energy string theory and
demonstrate how the gravitational interactions involving the axion and dilaton
fields may be derived from a geometrical action principle involving the
curvature scalar associated with a non-Riemannian connection. In this geometry
the antisymmetric tensor 3-form field determines the torsion of the connection
on the frame bundle while the gradient of the metric is determined by the
dilaton field. By expressing the theory in terms of the Levi-Civita connection
associated with the metric in the ``Einstein frame'' we confirm that the field
equations derived from the non-Riemannian Einstein-Hilbert action coincide with
the axi-dilaton sector of the low energy effective action derived from string
theory.Comment: 6 pages Plain Tex (No Figures), Letter to Editor Classical and
Quantum Gravit
Effectiveness of application of methods of physical rehabilitation in patients of pasty age on osteoarthros of column diseases
The article studies the clinical efficacy of the use of methods of physical rehabilitation in patients with osteoarthrosis of the knee joints. The rehabilitation program included post-isometric relaxation exercises and the volume pneumopressing technique for myocorrection, which contributed to the restoration of normal blood flow in the area of the nidus, strengthening muscles and improving joint function
Quantum Stephani Universe in vicinity of the symmetry center
We study a class of spherically symmetric Stephani cosmological models in the
presence of a self-interacting scalar field in both classical and quantum
domains. We discuss the construction of `canonical' wave packets resulting from
the solutions of a class of Wheeler-DeWitt equations in the Stephani Universe.
We suggest appropriate initial conditions which result in wave packets
containing some desirable properties, most importantly good classical and
quantum correspondence. We also study the situation from de-Broglie Bohm
interpretation of quantum mechanics to recover the notion of time and compare
the classical and Bohmian results. We exhibit that the usage of the canonical
prescription and appropriate choices of expansion coefficients result in the
suppression of the quantum potential and coincidence between classical and
Bohmian results. We show that, in some cases, contrary to
Friedmann-Robertson-Walker case, the bound state solutions also exist for all
positive values of the cosmological constant.Comment: 22 pages, 19 figures, to appear in JCA
The accumulation of deficits approach to describe frailty
The advancing age of the participants of the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam study was the incentive to investigate frailty as a major parameter of ageing. The aim of this study was to develop a multidimensional tool to measure frailty in an ageing, free-living study population. The "accumulation of deficits approach" was used to develop a frailty index (FI) to characterize a sub-sample (N = 815) of the EPIC-Potsdam (EPIC-P) study population regarding the aging phenomenon. The EPIC-P frailty index (EPIC-P-FI) included 32 variables from the following domains: health, physical ability, psychosocial and physiological aspects. P-values were calculated for the linear trend between sociodemographic and life style variables and the EPIC-P-FI was calculated using regression analysis adjusted for age. The relationship between the EPIC-P-FI and age was investigated using fractional polynomials. Some characteristics such as age, education, time spent watching TV, cycling and a biomarker of inflammation (C-reactive protein) were associated with frailty in men and women. Interestingly, living alone, having no partner and smoking status were only associated with frailty in men, and alcohol use and physical fitness (VO2max) only in women. The generated, multidimensional FI, adapted to the EPIC-P study, showed that this cohort is a valuable source for further exploration of factors that promote healthy ageing
Respiratory rehabilitation: a physiotherapy approach to the control of asthma symptoms and anxiety
OBJECTIVES: The objectives of this study were to verify the degree of anxiety, respiratory distress, and health-related quality of life in a group of asthmatic patients who have experienced previous panic attacks. Additionally, we evaluated if a respiratory physiotherapy program (breathing retraining) improved both asthma and panic disorder symptoms, resulting in an improvement in the health-related quality of life of asthmatics. METHODS: Asthmatic individuals were assigned to a chest physiotherapy group that included a breathing retraining program held once a week for three months or a paired control group that included a Subtle Touch program. All patients were assessed using the Diagnostic and Statistical Manual of Mental Disorders IV, the Sheehan Anxiety Scale, the Quality of Life Questionnaire, and spirometry parameter measurements. RESULTS: Both groups had high marks for panic disorder and agoraphobia, which limited their quality of life. The Breathing Retraining Group program improved the clinical control of asthma, reduced panic symptoms and agoraphobia, decreased patient scores on the Sheehan Anxiety Scale, and improved their quality of life. Spirometry parameters were unchanged. CONCLUSION: Breathing retraining improves the clinical control of asthma and anxiety symptoms and the health-related quality of life in asthmatic patients
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DESIGN OF BEAM TRANSFER LINES FOR THE NSLS II
The NSLS-II light source which is a proposed facility to be built at Brookhaven National Laboratory utilizes two synchrotron accelerator rings: the booster and the Storage ring (SR). Designing the NSLS-11 injector we considered two options for the booster layout, where the rings either (a) share the same tunnel, but placed at different horizontal planes or (b) booster is located in a separate building. The booster which accepts beam from the linac, accelerates the electron beam to an energy of 3.0 GeV and the beam is extracted to the Booster to Storage Ring (BtS) transport line which transports the beam and injects it into the SR ring. The design procedure for each of the two options of the BtS line and other details about the optics and the magnetic elements of the line are presented in this paper
Black Holes with Weyl Charge and Non-Riemannian Waves
A simple modification to Einstein's theory of gravity in terms of a
non-Riemannian connection is examined. A new tensor-variational approach yields
field equations that possess a covariance similar to the gauge covariance of
electromagnetism. These equations are shown to possess solutions analogous to
those found in the Einstein-Maxwell system. In particular one finds
gravi-electric and gravi-magnetic charges contributing to a spherically
symmetric static Reissner-Nordstr\"om metric. Such Weyl ``charges'' provide a
source for the non-Riemannian torsion and metric gradient fields instead of the
electromagnetic field. The theory suggests that matter may be endowed with
gravitational charges that couple to gravity in a manner analogous to
electromagnetic couplings in an electromagnetic field. The nature of
gravitational coupling to spinor matter in this theory is also investigated and
a solution exhibiting a plane-symmetric gravitational metric wave coupled via
non-Riemannian waves to a propagating spinor field is presented.Comment: 18 pages Plain Tex (No Figures), Classical and Quantum Gravit
CMB observations in LTB universes: Part I: Matching peak positions in the CMB spectrum
Acoustic peaks in the spectrum of the cosmic microwave background in
spherically symmetric inhomogeneous cosmological models are studied. At the
photon-baryon decoupling epoch, the universe may be assumed to be dominated by
non-relativistic matter, and thus we may treat radiation as a test field in the
universe filled with dust which is described by the Lema\^itre-Tolman-Bondi
(LTB) solution. First, we give an LTB model whose distance-redshift relation
agrees with that of the concordance CDM model in the whole redshift
domain and which is well approximated by the Einstein-de Sitter universe at and
before decoupling. We determine the decoupling epoch in this LTB universe by
Gamow's criterion and then calculate the positions of acoustic peaks. Thus
obtained results are not consistent with the WMAP data. However, we find that
one can fit the peak positions by appropriately modifying the LTB model,
namely, by allowing the deviation of the distance-redshift relation from that
of the concordance CDM model at where no observational data are
available at present. Thus there is still a possibility of explaining the
apparent accelerated expansion of the universe by inhomogeneity without
resorting to dark energy if we abandon the Copernican principle. Even if we do
not take this extreme attitude, it also suggests that local, isotropic
inhomogeneities around us may seriously affect the determination of the density
contents of the universe unless the possible existence of such inhomogeneities
is properly taken into account.Comment: 20 pages, 5 figure
Reading educational reform with actor network theory: Fluid spaces, otherings, and ambivalences
In considering two extended examples of educational reform efforts, this discussion traces relations that become visible through analytic approaches associated with actor-network theory (ANT). The strategy here is to present multiple readings of the two examples. The first reading adopts an ANT approach to follow ways that all actors – human and non-human entities, including the entity that is taken to be ‘educational reform’ – are performed into being through the play of linkages among heterogeneous elements. Then, further readings focus not only on the material practices that become enacted and distributed, but also on the otherings that occur: the various fluid spaces and ambivalent belongings that create actor-network(s) but also escape them. For educational research, particularly in educational reform and policy, it is argued that ANT analyses are particularly useful to examine the complex enactments in these dynamics. That is, ANT can illuminate movements of ordering and disordering that occur through minute socio-material connections in educational interventions. ANT readings also can discern, within these attempts to order people and practices, the spaces of flux and instability that enable and protect alternate possibilities
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