International School for Advanced Studies

About: International School for Advanced Studies is a education organization based out in Trieste, Friuli-Venezia Giulia, Italy. It is known for research contribution in the topics: Galaxy & Dark matter. The organization has 3751 authors who have published 13433 publications receiving 588454 citations. The organization is also known as: SISSA & Scuola Internazionale Superiore di Studi Avanzati.

Existence and symmetry results for a Schrödinger type problem involving the fractional Laplacian

Abstract: This paper deals with the following class of nonlocal Schrodinger equations (-\Delta)^s u + u = |u|^{p-1}u in \mathbb{R}^N, for s\in (0,1). We prove existence and symmetry results for the solutions $u$ in the fractional Sobolev space H^s(\mathbb{R}^N). Our results are in clear accordance with those for the classical local counterpart, that is when s=1.

Planck early results - XI. Calibration of the local galaxy cluster Sunyaev-Zeldovich scaling relations

Abstract: We present precise Sunyaev-Zeldovich (SZ) effect measurements in the direction of 62 nearby galaxy clusters (z < 0.5) detected at high signal-tonoise in the first Planck all-sky data set. The sample spans approximately a decade in total mass, 2 × 10 14 M� < M500 < 2 × 10 15 M� ,w hereM500 is the mass corresponding to a total density contrast of 500. Combining these high quality Planck measurements with deep XMM-Newton X-ray data, we investigate the relations between D 2 Y500, the integrated Compton parameter due to the SZ effect, and the X-ray-derived gas mass Mg,500, temperature TX, luminosity LX,500, SZ signal analogue YX,500 = Mg,500 ×TX, and total mass M500. After correction for the effect of selection bias on the scaling relations, we find results that are in excellent agreement with both X-ray predictions and recently-published ground-based data derived from smaller samples. The present data yield an exceptionally robust, high-quality local reference, and illustrate Planck’s unique capabilities for all-sky statistical studies of galaxy clusters.

Model Order Reduction in Fluid Dynamics: Challenges and Perspectives

Abstract: This chapter reviews techniques of model reduction of fluid dynamics systems. Fluid systems are known to be difficult to reduce efficiently due to several reasons. First of all, they exhibit strong nonlinearities — which are mainly related either to nonlinear convection terms and/or some geometric variability — that often cannot be treated by simple linearization. Additional difficulties arise when attempting model reduction of unsteady flows, especially when long-term transient behavior needs to be accurately predicted using reduced order models and more complex features, such as turbulence or multiphysics phenomena, have to be taken into consideration. We first discuss some general principles that apply to many parametric model order reduction problems, then we apply them on steady and unsteady viscous flows modelled by the incompressible Navier-Stokes equations. We address questions of inf-sup stability, certification through error estimation, computational issues and — in the unsteady case — long-time stability of the reduced model. Moreover, we provide an extensive list of literature references.

Annual fishes of the genus Nothobranchius as a model system for aging research

Abstract: Summary Aging research in vertebrates is hampered by the lack of short- lived models. Annual fishes of the genus Nothobranchius live in East African seasonal ponds. Their life expectancy in the wild is limited by the duration of the wet season and their lifespan in captivity is also short. Nothobranchius are popular aquarium fishes and many different species are kept as captive strains, providing rich material for comparative studies. The present paper aims at reviving the interest in these fishes by reporting that: (1) Nothobranchius can be cultured, and their eggs stored dry at room temperature for months or years, offering inexpensive methods of embryo storage; (2) Nothobranchius show accelerated growth and expression of aging biomarkers at the level of histology and behaviour; (3) the species Nothobranchius furzeri has a maximum lifespan of only 3 months and offers the possibility to perform investigations thus far unthinkable in a vertebrate, such as drug screening with life-long pharmacological treatments and experimental evolution; (4) when the lifespan of different species is compared, a general correlation is found between wet season duration in their natural habitat and longevity in captivity; and (5) vertebrate aging-related genes, such as p66Shc and MTP , can be easily isolated in Nothobranchius by homology cloning. These fishes can become excellent models for aging studies. They can be employed to test the effects of experimental manipulation on aging at a pace com- parable with that of Drosophila and to probe the effects of natural selection on the evolution of aging-related genes.

Gauge/gravity duality and meta-stable dynamical supersymmetry breaking

Abstract: We engineer a class of quiver gauge theories with several interesting features by studying D-branes at a simple Calabi-Yau singularity. At weak 't Hooft coupling we argue using field theory techniques that these theories admit both supersymmetric vacua and meta-stable non-supersymmetric vacua, though the arguments indicating the existence of the supersymmetry breaking states are not decisive. At strong 't Hooft coupling we find simple candidate gravity dual descriptions for both sets of vacua.