869 research outputs found
Hamiltonian structure and noncommutativity in -brane models with exotic supersymmetry
The Hamiltonian of the simplest super -brane model preserving 3/4 of the
D=4 N=1 supersymmetry in the centrally extended symplectic superspace is
derived and its symmetries are described. The constraints of the model are
covariantly separated into the first- and the second-class sets and the Dirac
brackets (D.B.) are constructed. We show the D.B. noncommutativity of the super
-brane coordinates and find the D.B. realization of the
superalgebra. Established is the coincidence of the D.B. and Poisson bracket
realizations of the superalgebra on the constraint surface and the
absence there of anomaly terms in the commutation relations for the quantized
generators of the superalgebra.Comment: Latex, 27 pages, no figures. Latex packages amsfonts and euscript are
use
Gravity, p-branes and a spacetime counterpart of the Higgs effect
We point out that the worldvolume coordinate functions of
a -brane, treated as an independent object interacting with dynamical
gravity, are Goldstone fields for spacetime diffeomorphisms gauge symmetry. The
presence of this gauge invariance is exhibited by its associated Noether
identity, which expresses that the source equations follow from the
gravitational equations. We discuss the spacetime counterpart of the Higgs
effect and show that a -brane does not carry any local degrees of freedom,
extending early known general relativity features. Our considerations are also
relevant for brane world scenarios.Comment: 5 pages, RevTeX. v2 (30-IV-03) with additional text and reference
Aspects of Superembeddings
Some aspects of the geometry of superembeddings and its application to
supersymmetric extended objects are discussed. In particular, the embeddings of
(3|16) and (6|16) dimensional superspaces into (11|32) dimensional superspace,
corresponding to supermembranes and superfivebranes in eleven dimensions, are
treated in some detail.Comment: 13 pages, Latex, Contribution to Supersymmetry and Quantum Field
Theory, International Seminar dedicated to the memory of D. V. Volkov
(Kharkov, 1997), some clarifications are mad
Society for Endocrinology UK guidance on the initial evaluation of an infant or an adolescent with a suspected disorder of sex development (Revised 2015)
It is paramount that any child or adolescent with a suspected disorder of sex development (DSD) is assessed by an experienced clinician with adequate knowledge about the range of conditions associated with DSD. If there is any doubt, the case should be discussed with the regional DSD team. In most cases, particularly in the case of the newborn, the paediatric endocrinologist within the regional team acts commonly as the first point of contact. This clinician should be part of a multidisciplinary team experienced in management of DSD and should ensure that the affected person and parents have access to specialist psychological support and that their information needs are comprehensively addressed. The underlying pathophysiology of DSD and the strengths and weaknesses of the tests that can be performed should be discussed with the parents and affected young person and tests undertaken in a timely fashion. Finally, in the field of rare conditions, it is imperative that the clinician shares the experience with others through national and international clinical and research collaboration
D0 and D1 Brane With and Extended Symmetry
D0 brane (D-particle) and D1 brane actions possess first and second class
constraints that result in local symmetry. The symmetry of
the D-particle and the D1 brane is extended here into a larger symmetry
( and ) in a larger phase space by turning second class
constraints into first class. Different gauge fixings of these symmetries
result in different presentations of these systems while a "unitary" gauge
fixing of the new symmetry retrieves the original action with
symmetry. For D1 brane our extended phase space makes all
constraints into first class in the case of vanishing world sheet electric
field (namely string).Comment: A new section on D1 brane with extended kappa symmetry has been
added, references have been added. (18 pages, Latex file
Boundary driven zero-range processes in random media
The stationary states of boundary driven zero-range processes in random media
with quenched disorder are examined, and the motion of a tagged particle is
analyzed. For symmetric transition rates, also known as the random barrier
model, the stationary state is found to be trivial in absence of boundary
drive. Out of equilibrium, two further cases are distinguished according to the
tail of the disorder distribution. For strong disorder, the fugacity profiles
are found to be governed by the paths of normalized -stable
subordinators. The expectations of integrated functions of the tagged particle
position are calculated for three types of routes.Comment: 23 page
A single-center, observational study of 607 children & young people presenting with Differences in Sex Development (DSD)
Context
Differences in sex development (DSD) represent a wide range of conditions presenting at different ages to various health professionals. Establishing a diagnosis, supporting the family and developing a management plan are important.
Objective
We aimed to better understand the presentation and prevalence of pediatric DSD.
Design
A retrospective, observational cohort study was undertaken of all children and young people (CYP) referred to a DSD multi-disciplinary team over 25 years (1995-2019).
Setting
A single tertiary paediatric center.
Participants
In total, 607 CYP (520 regional referrals) were included.
Main Outcome Measures
Data were analyzed for diagnosis, sex-assignment, age and mode of presentation, additional phenotypic features, mortality, and approximate point prevalence.
Results
Amongst the three major DSD categories, sex chromosome DSD was diagnosed in 11.2% (68/607) (most commonly 45, X/46, XY mosaicism), 46, XY DSD in 61.1% (371/607) (multiple diagnoses often with associated features), while 46, XX DSD occurred in 27.7% (168/607) (often 21-hydroxylase deficiency). Most children (80.1%) presented as neonates, usually with atypical genitalia, adrenal insufficiency, undescended testes or herniae. Those presenting later had diverse features. Rarely, the diagnosis was made antenatally (3.8%, n = 23) or following incidental karyotyping/family history (n = 14). Mortality was surprisingly high in 46, XY children, usually due to complex associated features (46, XY girls, 8.3%; 46, XY boys, 2.7%). The approximate point prevalence of neonatal referrals for investigation of DSD was 1 in 6,347 births, and 1 in 5,101 overall throughout childhood.
Conclusions
DSD represent a diverse range of conditions that can present at different ages. Pathways for expert diagnosis and management are important to optimize care
Study of variable stars in the MOA data base: long-period red variables in the Large Magellanic Cloud
One hundred and forty six long-period red variable stars in the Large
Magellanic Cloud (LMC) from the three year MOA project database were analysed.
A careful periodic analysis was performed on these stars and a catalogue of
their magnitudes, colours, periods and amplitudes is presented. We convert our
blue and red magnitudes to band values using 19 oxygen-rich stars. A group
of red short-period stars separated from the Mira sequence has been found on a
(log P, K) diagram. They are located at the short period side of the Mira
sequence consistent with the work of Wood and Sebo (1996). There are two
interpretations for such stars; a difference in pulsation mode or a difference
in chemical composition. We investigated the properties of these stars together
with their colour, amplitude and periodicity. We conclude that they have small
amplitudes and less regular variability. They are likely to be higher mode
pulsators. A large scatter has been also found on the long period side of the
(log P, K) diagram. This is possibly a systematic spread given that the blue
band of our photometric system covers both standard B and V bands and affects
carbon-rich stars.Comment: 19 pages, 19 figures, accepted for publication in MNRA
Study of the radiative decay with CMD-2 detector
Using the of data collected with the CMD-2 detector at VEPP-2M
the decay mode , has been
studied. The obtained branching ratio is B(.Comment: 13 pages, 5 figures, LaTex2e, to be published in Phys. Lett.
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