79 research outputs found
Hoop conjecture for colliding black holes : non-time-symmetric initial data
The hoop conjecture is well confirmed in momentarily static spaces, but it
has not been investigated systematically for the system with relativistic
motion. To confirm the hoop conjecture for non-time-symmetric initial data, we
consider the initial data of two colliding black holes with momentum and search
an apparent horizon that encloses two black holes. In testing the hoop
conjecture, we use two definitions of gravitational mass : one is the ADM mass
and the other is the quasi-local mass defined by Hawking. Although both
definitions of gravitational mass give fairly consistent picture of the hoop
conjecture, the hoop conjecture with the Hawking mass can judge the existence
of an apparent horizon for wider range of parameters of the initial data
compared to the ADM mass.Comment: 15pages, 4 figure
Realistic D-Brane Models on Warped Throats: Fluxes, Hierarchies and Moduli Stabilization
We describe the construction of string theory models with semirealistic
spectrum in a sector of (anti) D3-branes located at an orbifold singularity at
the bottom of a highly warped throat geometry, which is a generalisation of the
Klebanov-Strassler deformed conifold. These models realise the Randall-Sundrum
proposal to naturally generate the Planck/electroweak hierarchy in a concrete
string theory embedding, and yielding interesting chiral open string spectra.
We describe examples with Standard Model gauge group (or left-right symmetric
extensions) and three families of SM fermions, with correct quantum numbers
including hypercharge. The dilaton and complex structure moduli of the geometry
are stabilised by the 3-form fluxes required to build the throat. We describe
diverse issues concerning the stabilisation of geometric Kahler moduli, like
blow-up modes of the orbifold singularities, via D term potentials and gauge
theory non-perturbative effects, like gaugino condensation. This local
geometry, once embedded in a full compactification, could give rise to models
with all moduli stabilised, and with the potential to lead to de Sitter vacua.
Issues of gauge unification, proton stability, supersymmetry breaking and
Yukawa couplings are also discussed.Comment: 46 pages, 13 figures (figures 3 and 13 corrected
Adsorption-desorption kinetics in nanoscopically confined oligomer films under shear
The method of molecular dynamics computer simulations is employed to study oligomer melts confined in ultra-thin films and subjected to shear. The focus is on the self-diffusion of oligomers near attractive surfaces and on their desorption, together with the effects of increasing energy of adsorption and shear. It is found that the mobility of the oligomers near an attractive surface is strongly decreased. Moreover, although shearing the system forces the chains to stretch parallel to the surfaces and thus increase the energy of adsorption per chain, flow also promotes desorption. The study of chain desorption kinetics reveals the molecular processes responsible for the enhancement of desorption under shear. They involve sequences of conformations starting with a desorbed tail and proceeding in a very fast, correlated, segment-by-segment manner to the desorption of the oligomers from the surfaces.
Local models for intersecting brane worlds
We describe the construction of configurations of D6-branes wrapped on
compact 3-cycles intersecting at points in non-compact Calabi-Yau threefolds.
Such constructions provide local models of intersecting brane worlds, and
describe sectors of four-dimensional gauge theories with chiral fermions. We
present several classes of non-compact manifolds with compact 3-cycles
intersecting at points, and discuss the rules required for model building with
wrapped D6-branes. The rules to build 3-cycles are simple, and allow easy
computation of chiral spectra, RR tadpoles and the amount of preserved
supersymmetry. We present several explicit examples of these constructions,
some of which have Standard Model like gauge group and three quark-lepton
generations. In some cases, mirror symmetry relates the models to other
constructions used in phenomenological D-brane model building, like D-branes at
singularities. Some simple N=1 supersymmetric configurations may lead to
relatively tractable G_2 manifolds upon lift to M-theory, which would be
non-compact but nevertheless yield four-dimensional chiral gauge field
theories.Comment: 52 pages, latex, 24 enclosed eps figures; v2. typo correcte
ReïŹning and regaining skills in ïŹxation/diversiïŹcation stage performers: The Five-A Model
Technical change is one of many factors underpinning success in elite, fixation/diversification stage performers. Surprisingly, however, there is a dearth of research pertaining to this process or the most efficacious methods used to bring about such a change. In this paper we highlight the emergent processes, yet also the lack in mechanistic comprehension surrounding technical change, addressing issues within the motor control, sport psychology, coaching and choking literature. More importantly, we seek an understanding of how these changes can be made more secure to competitive pressure, and how this can be embedded within the process of technical change. Following this review, we propose The Five-A Model based on successful coaching techniques, psychosocial concomitants, the avoidance of choking and principles of effective behaviour change. Specific mechanisms for each stage are discussed, with a focus on the use of holistic rhythm-based cues as a possible way of internalising changes. Finally, we suggest the need for further research to examine these five stages, to aid a more comprehensive construction of the content and delivery of such a programme within the applied setting
Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.
BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362
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