190 research outputs found
The long QT syndrome in South Africa
The long QT syndromes (LQTS) are Mendelian inherited conditions where syncope and sudden death are due to precipitous occurrence of polymorphic ventricular tachycardia. In South Africa a number of white, some coloured and some Asian individuals have been identified but, interestingly, not a single black person and neither has it been reported from Africa. With over 400 known causal-mutations, mostly in cardiac ion channel-genes, it is unlikely to be absent in African populations. LQTS is notorious for going undiagnosed or misdiagnosed, perhaps even more so in Africa. Amongst persons of Afrikaner descent the KCNQ1 A341V-mutation represents a founder effect. The availability of 170 living individuals sharing the same mutation has made it possible to study factors modifying risk. A blunted autonomic response has been shown to decrease risk of attacks
The Covariant Quantum Superstring and Superparticle from their Classical Actions
We develop an approach based on the Noether method to construct nilpotent
BRST charges and BRST-invariant actions. We apply this approach first to the
holomorphic part of the flat-space covariant superstring, and we find that the
ghosts b, c_z which we introduced by hand in our earlier work, are needed to
fix gauge symmetries of the ghost action. Then we apply this technique to the
superparticle and determine its cohomology. Finally, we extend our results to
the combined left- and right-moving sectors of the superstring.Comment: 14 pages, harmva
A New First Class Algebra, Homological Perturbation and Extension of Pure Spinor Formalism for Superstring
Based on a novel first class algebra, we develop an extension of the pure
spinor (PS) formalism of Berkovits, in which the PS constraints are removed. By
using the homological perturbation theory in an essential way, the BRST-like
charge of the conventional PS formalism is promoted to a bona fide
nilpotent charge , the cohomology of which is equivalent to the
constrained cohomology of . This construction requires only a minimum number
(five) of additional fermionic ghost-antighost pairs and the vertex operators
for the massless modes of open string are obtained in a systematic way.
Furthermore, we present a simple composite "-ghost" field which
realizes the important relation , with the
Virasoro operator, and apply it to facilitate the construction of the
integrated vertex. The present formalism utilizes U(5) parametrization and the
manifest Lorentz covariance is yet to be achieved.Comment: 38 pages, no figure. Proof of triviality of delta-homology improved
and a reference adde
Origin of Pure Spinor Superstring
The pure spinor formalism for the superstring, initiated by N. Berkovits, is
derived at the fully quantum level starting from a fundamental
reparametrization invariant and super-Poincare invariant worldsheet action. It
is a simple extension of the Green-Schwarz action with doubled spinor degrees
of freedom with a compensating local supersymmetry on top of the conventional
kappa-symmetry. Equivalence to the Green-Schwarz formalism is manifest from the
outset. The use of free fields in the pure spinor formalism is justified from
the first principle. The basic idea works also for the superparticle in 11
dimensions.Comment: 21 pages, no figure; v2: refs. adde
Randomised controlled trial of a secondary prevention program for myocardial infarction patients ('ProActive Heart'): study protocol. Secondary prevention program for myocardial infarction patients
Background: Coronary heart disease (CHD) is a significant cause of health and economic burden. Secondary prevention programs play a pivotal role in the treatment and management of those affected by CHD although participation rates are poor due to patient, provider, health system and societal-level barriers. As such, there is a need to develop innovative secondary prevention programs to address the treatment gap. Telephone-delivered care is convenient, flexible and has been shown to improve behavioural and clinical outcomes following myocardial infarction (MI). This paper presents the design of a randomised controlled trial to evaluate the efficacy of a six-month telephone-delivered secondary prevention program for MI patients (ProActive Heart). Methods: 550 adult MI patients have been recruited over a 14 month period (December 2007 to January 2009) through two Brisbane metropolitan hospitals, and randomised to an intervention or control group (n = 225 per group). The intervention commences within two weeks of hospital discharge delivered by study-trained health professionals ('health coaches') during up to 10 Ă— 30 minute scripted telephone health coaching sessions. Participants also receive a ProActive Heart handbook and an educational resource to use during the health coaching sessions. The intervention focuses on appropriate modification of CHD risk factors, compliance with pharmacological management, and management of psychosocial issues. Data collection occurs at baseline or prior to commencement of the intervention (Time 1), six months follow-up or the completion of the intervention (Time 2), and at 12 months follow-up for longer term outcomes (Time 3). Primary outcome measures include quality of life (Short Form-36) and physical activity (Active Australia Survey). A cost-effective analysis of the costs and outcomes for patients in the intervention and control groups is being conducted from the perspective of health care costs to the government. Discussion: The results of this study will provide valuable new information about an innovative telephone-delivered cost-effective secondary prevention program for MI patients
N=2 Superparticles, RR Fields and Noncommutative Structures of (super)-Spacetime
The recent developments in superstring theory prompted the study of
non-commutative structures in superspace. Considering bosonic and fermionic
strings in a constant antisymmetric tensor background yields a non-vanishing
commutator between the bosonic coordinates of the spacetime. Likewise, the
presence of constant Ramond-Ramond (RR) background leads to a non-vanishing
anti-commutator for the Grassmann coordinates of the superspace. The
non-vanishing commutation relation between bosonic coordinates can also be
derived using a particle moving in a magnetic background, we use N=2 pure
spinor superparticles and D0-branes to show how the non-commutative structures
emerge in superspace. It is argued how a D0-brane in a background of RR fields
reproduces the results obtained in string theory.Comment: Based on a lectures given at 43rd International School of Subnuclear
Physics, Erice, Sicily, Italy, Aug. 200
Understanding relations between intolerance of uncertainty and body checking and body avoiding in anorexia nervosa
Background: A key feature of anorexia nervosa is body image disturbances and is often expressed by dysfunctional body-related behaviours such as body checking and body avoiding. These behaviours are thought to contribute to both the maintenance and relapse of AN, yet empirical evidence is scarce. One variable that may contribute to the need for engaging in these behaviours is intolerance of uncertainty. This study aims to investigate body checking and body avoiding and its relations with intolerance of uncertainty in women with anorexia nervosa (AN-ill; 70), women recovered from AN (AN-rec; 85) and control group (127). Methods: Three questionnaires were completed, measuring eating pathology, intolerance of uncertainty and body checking and body avoiding. One-way ANOVAS were used to test group differences. Moderation analyses were used to investigate associations between variables. Results: Levels of intolerance of uncertainty, body checking and body avoiding were highest in AN-ill followed by AN-rec and, lastly, the control group, confirming group differences. Intolerance of uncertainty was associated with body checking in the AN-rec group and the control group but not in the AN-ill group. The association between intolerance of uncertainty and body avoiding was reported in the AN-rec group and only marginally in the control group. Conclusion: Levels of intolerance of uncertainty, body checking and body avoiding were highest in AN-ill, however still elevated in AN-rec, confirming the presence of body image disturbances, even after recovery. The unique associations between intolerance of uncertainty and body checking and body avoiding within the studied groups may represent different stages of the illness. In the AN-rec group, the relation between intolerance of uncertainty, body checking and body avoiding may be driven by trait anxiety. For AN-ill group, body checking and body avoiding may eventually have grown into habitual patterns, rather than a strategy to ameliorate anxiety and uncertainty. Plain English summary: Women with anorexia nervosa often experience disturbances in their body image and are expressed in body-related behaviours such as body checking and body avoiding. These behaviours are thought to contribute to both the maintenance and relapse of anorexia nervosa. Intolerance of uncertainty is defined as the incapacity to tolerate uncertainty and may contribute to the need for engaging in these behaviours. This study aims to investigate body checking and body avoiding and its relations with intolerance of uncertainty in women with anorexia nervosa (AN-ill; 70), women recovered from AN (AN-rec; 85) and control group (127). Three questionnaires were completed, measuring eating pathology, intolerance of uncertainty and body checking and body avoiding. Levels of intolerance of uncertainty, body checking and body avoiding were highest in AN-ill and still elevated in AN-rec, even after recovery. The associations between intolerance of uncertainty and body checking and body avoiding within the studied groups may represent different stages of the illness. In the AN-rec group, the relation between intolerance of uncertainty, body checking and body avoiding may be driven by trait anxiety. For AN-ill group, body checking and body avoiding may have grown into habitual patterns, rather than a strategy to ameliorate anxiety and uncertainty
Superstar in Noncommutative Superspace via Covariant Quantization of the Superparticle
A covariant quantization method is developed for the off-shell superparticle
in 10 dimensions. On-shell it is consistent with lightcone quantization, while
off-shell it gives a noncommutative superspace that realizes non-linearly a
hidden 11-dimensional super Poincare symmetry. The non-linear commutation rules
are then used to construct the supersymmetric generalization of the covariant
Moyal star product in noncommutative superspace. As one of the possible
applications, we propose this new product as the star product in supersymmetric
string field theory. Furthermore, the formalism introduces new techniques and
concepts in noncommutative (super)geometry.Comment: 17 pages, LaTe
Nonrelativistic anyons in external electromagnetic field
The first-order, infinite-component field equations we proposed before for
non-relativistic anyons (identified with particles in the plane with
noncommuting coordinates) are generalized to accommodate arbitrary background
electromagnetic fields. Consistent coupling of the underlying classical system
to arbitrary fields is introduced; at a critical value of the magnetic field,
the particle follows a Hall-like law of motion. The corresponding quantized
system reveals a hidden nonlocality if the magnetic field is inhomogeneous. In
the quantum Landau problem spectral as well as state structure (finite vs.
infinite) asymmetry is found. The bound and scattering states, separated by the
critical magnetic field phase, behave as further, distinct phases.Comment: 19 pages, typos corrected; to appear in Nucl. Phys.
Covariant Quantization of the Brink-Schwarz Superparticle
The quantization of the Brink-Schwarz-Casalbuoni superparticle is performed
in an explicitly covariant way using the antibracket formalism. Since an
infinite number of ghost fields are required, within a suitable off-shell
twistor-like formalism, we are able to fix the gauge of each ghost sector
without modifying the physical content of the theory. The computation reveals
that the antibracket cohomology contains only the physical degrees of freedom.Comment: 24 page
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