6,145 research outputs found
M-Theory in the Gaugeon Formalism
In this paper we will analyse the Aharony-Bergman-Jafferis-Maldacena (ABJM)
theory in superspace formalism. We then study the quantum gauge
transformations for this ABJM theory in gaugeon formalism. We will also analyse
the extended BRST symmetry for this ABJM theory in gaugeon formalism and show
that these BRST transformations for this theory are nilpotent and this in turn
leads to the unitary evolution of the -matrix.Comment: 8 pages, 0 figures, accepted for publication in Comm. Theor. Phy
Unstable Disk Galaxies. II. the Origin of Growing and Stationary Modes
I decompose the unstable growing modes of stellar disks to their Fourier
components and present the physical mechanism of instabilities in the context
of resonances. When the equilibrium distribution function is a non-uniform
function of the orbital angular momentum, the capture of stars into the
corotation resonance imbalances the disk angular momentum and triggers growing
bar and spiral modes. The stellar disk can then recover its angular momentum
balance through the response of non-resonant stars. I carry out a complete
analysis of orbital structure corresponding to each Fourier component in the
radial angle, and present a mathematical condition for the occurrence of van
Kampen modes, which constitute a continuous family. I discuss on the
discreteness and allowable pattern speeds of unstable modes and argue that the
mode growth is saturated due to the resonance overlapping mechanism. An
individually growing mode can also be suppressed if the corotation and inner
Lindblad resonances coexist and compete to capture a group of stars. Based on
this mechanism, I show that self-consistent scale-free disks with a sufficient
distribution of non-circular orbits should be stable under perturbations of
angular wavenumber . I also derive a criterion for the stability of
stellar disks against non-axisymmetric excitations.Comment: 15 Pages (emulateapj), 7 Figures, Accepted for Publication in The
Astrophysical Journa
Antidepressant medication and ocular factors in association with the need for anti-VEGF retreatment in neovascular age-related macular degeneration.
Vascular endothelial growth factor (VEGF) is a key player in the pathogenesis of neovascular age-related macular degeneration (nAMD) and is also involved in the final common pathway of antidepressant medication. This study investigated the relationship between the need for anti-VEGF retreatment in patients with nAMD and antidepressant medication, and the potential impact of ocular structural factors.
Data from two identical prospective 2-year treatment protocols using ranibizumab or aflibercept in a variable-dosing regimen ('Observe-and-Plan') were analysed. Retreatment requirement was compared with antidepressant medication intake (primary outcome) and a variety of ocular factors from baseline and from month 3 response (secondary outcomes), using univariate and multivariate analyses.
Of the 206 included patients (227 eyes), 19 were on antidepressant medication. Their nAMD eyes significantly more often had pigment epithelium detachment (PED, p=0.04). Multivariate analysis revealed a significant association between anti-VEGF retreatment requirement and antidepressant medication use (p=0.027), as well as thicker central retinal thickness at month 3 (p<0.0001) and month 3 PED height (p=0.001).
This study provides evidence that treatment with antidepressant medication increases the anti-VEGF retreatment requirement in patients with nAMD, possibly through the interplay of antidepressant medication, depression status and VEGF levels
Quaternions : a mathematica package for quaternionic analysis
This paper describes new issues of the Mathematica standard package Quaternions for implementing Hamilton's Quaternion Algebra.
This work attempts to endow the original package with the ability to perform operations on symbolic expressions involving quaternion-valued functions.
A collection of new functions is introduced in order to provide basic mathematical tools necessary for dealing with regular functions in , for . The performance of the package is illustrated by presenting several examples and applications.Centro de Matemática da Universidade do MinhoFundação para a Ciência e a Tecnologia (FCT)Centro de Investigação e Desenvolvimento em Matemática e Aplicações da Universidade de Aveir
Deformation of the ABJM Theory
In this paper we analyse the ABJM theory on deformed spacetime. We show that
this theory reduces to a deformed super-Yang-Mills theory when one of the
scalar superfields is given a non-vanishing vacuum expectation value. Our
analyse is done in N=1 superspace formulism.Comment: 10 pages, 0 figures, accepted for publication in EP
Síntesis, caracterización y evaluación eléctrica de circonatos de bario dopados con lantánidos trivalentes
El circonato de bario es un material oxídico con estructura de tipo perovskita que muestra alta estabilidad química tanto
en ambientes oxidantes como reductores, como en presencia de agua y dióxido de carbono; su conductividad ha permitido
examinarlo como electrolito para celdas de combustible de óxido sólido encontrando buenos resultados, con la limitante de
operar a temperaturas superiores a los 800 °C.
Diversos investigadores han propuesto que es posible mejorar su conductividad eléctrica por modifi caciones en su composición
química, en particular por dopaje con cationes trivalentes que reemplacen el circonio en el sitio B de la perovskita. En este
estudio se sintetizó el circonato de bario por el método citrato amorfo a fi n examinar la posibilidad de obtenerlo en condiciones
más favorables que las presentadas por el método de síntesis convencional (método cerámico o reacción de estado sólido).
Se preparó circonato de bario dopado con europio, gadolinio, holmio, lantano, neodimio y praseodimio; la identifi cación
de fases presentes se verifi có por difracción de rayos X (DRX), las propiedades eléctricas se examinaron por espectroscopía
de impedancias (IS) a temperaturas entre 480 y 680 °C, con miras a evaluar su potencial uso como electrolito en celdas de
combustible de óxido sólido.
Los aportes de esta investigación se han centrado en el método de síntesis; en la obtención de polvos cerámicos de circonato de
bario a temperaturas inferiores a las requeridas por el método cerámico; en la obtención de información química, estructural,
morfológica y eléctrica de los materiales sintetizados.
Se encontró la fase deseada en las condiciones de síntesis establecidas, así mismo, se aprecia un incremento signifi cativo en la
conductividad de los sólidos dopados con lantano, holmio y europio en relación al material sin dopaje alguno.Barium zirconate is an oxidic material having perovskite structure that exhibits high chemical stability in both oxidizing
and reducing environments, such as in the presence of water and carbon dioxide, its conductivity has led to consider it as a
electrolyte for solid oxide fuel cell fi nding good results, with the limitation of operating at temperatures above 800 °C.
Several researchers have proposed that it is possible to improve their electrical conductivity by changes in chemical composition,
particularly for doping with trivalent cations that replace the zirconium in B site of perovskite. In this study, barium zirconate
was synthetized by the amorphous citrate method to examine the possibility of obtaining in more favorable conditions than
those made by the conventional method of synthesis (ceramic method or solid state reaction) conditions are synthesized.
Barium zirconate doped with europium, gadolinium, holmium, lanthanum, neodymium and praseodymium was prepared,
the present phase identifi cation was verifi ed by X-ray diffraction (XRD), the electrical properties were examined by impedance
spectroscopy (IS) at temperatures between 480 and 680 °C in order to evaluate its potential use as a fuel cell electrolyte in solid oxide.
The contributions of this research has focused on the synthesis method, in the production of ceramic powders of barium
zirconate at temperatures lower than those required by the ceramic method, in obtaining chemical, structural, morphological
and electrical information of material synthesized.
The desired phase synthesis conditions set found, also, a signifi cant increase is seen in the solid conductivity of doped
lanthanum, holmium and europium zirconate of barium in relation to the material without doping
TCT-66 Door to Impella Placement in Acute Coronary Syndrome Complicated by Cardiogenic Shock: An Updated Meta-analysis
Background: The impact of time to hemodynamic support in acute myocardial infarction complicated by cardiogenic shock (AMICS) has yet to be defined. The aim of this meta-analysis was to evaluate the impact of timing of mechanical circulatory support (MCS) with Impella.
Methods: a systematic literature review and meta-analysis was conducted using PubMed and Cochrane databases. All studies reporting short-term mortality rates and timing of Impella insertion, pre vs during/post PCI, were included. Primary end point was short-term mortality (≤30 days), while secondary end pointswere midterm mortality, device-related bleeding and limb ischemia.
Results: Of 1,289 studies identified, 13 studies (6,810 patients; 2,970 patients identified as receiving Impella before PCI and 3,840 patients receiving Impella during/after PCI) were included in this analysis. Median age was 63.8 years (IQR 63-65.7 years), 76% of patients were male, and a high prevalence of cardiovascular risk factors was noted across the entire population. Short-term mortality was significantly reduced in those receiving pre-PCI Impella support, 37.2% vs 53.6% (RR 0.7; CI 0.56-0.88). Midterm mortality was also lower in the pre-PCI group, 47.9% vs 73% (RR 0.81; CI 0.68-0.97). The rates of device-related bleeding (RR 1.05; CI 0.47-2.33) and limb ischemia (RR 1.6; CI 0.63-2.15) were similar between the two groups.
Conclusion: This analysis suggests that MCS placement with Impella prior to PCI in AMICS may have a positive impact on short- and midterm mortality compared with post-PCI placement, with similar outcome in terms of safety.
Categories: CORONARY: Hemodynamic Support and Cardiogenic Shoc
Electroweak Physics, Experimental Aspects
Collider measurements on electroweak physics are summarised. Although the
precision on some observables is very high, no deviation from the Standard
Model of electroweak interactions is observed. The data allow to set stringent
limits on some models for new physics.Comment: Plenary Talk at the UK Phenomenology Workshop on Collider Physics,
Durham, 199
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