869 research outputs found

    Hamiltonian structure and noncommutativity in pp-brane models with exotic supersymmetry

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    The Hamiltonian of the simplest super pp-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 pp-brane coordinates and find the D.B. realization of the OSp(1∣8)OSp(1|8) superalgebra. Established is the coincidence of the D.B. and Poisson bracket realizations of the OSp(1∣8)OSp(1|8) 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

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    We point out that the worldvolume coordinate functions x^μ(ξ)\hat{x}^\mu(\xi) of a pp-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 pp-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

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    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)

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    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 κ−\kappa_- and κ+\kappa_+ Extended Symmetry

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    D0 brane (D-particle) and D1 brane actions possess first and second class constraints that result in local κ\kappa symmetry. The κ\kappa symmetry of the D-particle and the D1 brane is extended here into a larger symmetry (κ−\kappa_- and κ+\kappa_+) 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 κ+ \kappa_+ symmetry retrieves the original action with κ−=κ\kappa_- = \kappa symmetry. For D1 brane our extended phase space makes all constraints into first class in the case of vanishing world sheet electric field (namely (0,1)(0, 1) 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

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    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 α\alpha-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)

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    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

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    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 KK 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 ϕ→ηγ\phi \to \eta \gamma with CMD-2 detector

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    Using the 1.9pb−11.9 pb^{-1} of data collected with the CMD-2 detector at VEPP-2M the decay mode ϕ→ηγ\phi \to \eta \gamma, η→π+π−π0\eta \to \pi^+\pi^-\pi^0 has been studied. The obtained branching ratio is B(ϕ→ηγ)=(1.18±0.03±0.06)\phi \to \eta \gamma) = (1.18 \pm 0.03 \pm 0.06) %.Comment: 13 pages, 5 figures, LaTex2e, to be published in Phys. Lett.
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