p-brane superalgebras via integrability

It has long been appreciated that superalgebras with bosonic and fermionic generators additional to those in the super-Poincare algebra underlie p-brane and D-brane actions in superstring theory. These algebras have been revealed via "bottom up" approaches, involving consideration of Noether charges, and by "top down" approaches, involving the construction of manifestly supersymmetry invariant Wess-Zumino actions. In this paper, we give an alternative derivation of these algebras based on integrability of supersymmetry transformations assigned to fields in order to solve a cohomology problem related to the construction of Wess-Zumino terms for p-brane and D-brane actions.Comment: 22 pages, typo corrected, reference adde

Deriving all p-brane superalgebras via integrability

In previous work we demonstrated that the enlarged super-Poincare algebras which underlie p-brane and D-brane actions in superstring theory can be directly determined based on the integrability of supersymmetry transformations assigned to fields appearing in Wess-Zumino terms. In that work we derived p-brane superalgebras for p = 2 and 3. Here we extend our previous results and give a compact expression for superalgebras for all valid p.Comment: 26 pages, table added, typos corrected, a few remarks added for clarificatio

Constrained Simulations of the Magnetic Field in the Local Supercluster and the Propagation of UHECR

Magnetic fields (MF) in the Local Supercluster (LSC) of galaxies may have profound consequences for the propagation of Ultra High Energy Cosmic Rays (UHECR). Faraday rotations measurements provide some informations about MF in compact clusters. However, very few is known about less dense regions and about the global structure of MF in the LSC. In order to get a better knowledge of these fields we are performing constrained magnetohydrodynamical simulations of the LSC magnetic field. We will present the results of our simulation and discuss their implications for the angular distribution of expected UHECR deflections.Comment: 4 pages + 1 figure. Published on the Proceedings of the 28th International Cosmic Ray Conference, Tsukuba, Japan (2003

Heat transfer and wall temperature effects in shock wave turbulent boundary layer interactions

Direct numerical simulations are carried out to investigate the effect of the wall temperature on the behavior of oblique shock-wave/turbulent boundary layer interactions at freestream Mach number $2.28$ and shock angle of the wedge generator $\varphi = 8^{\circ}$. Five values of the wall-to-recovery-temperature ratio ($T_w/T_r$) are considered, corresponding to cold, adiabatic and hot wall thermal conditions. We show that the main effect of cooling is to decrease the characteristic scales of the interaction in terms of upstream influence and extent of the separation bubble. The opposite behavior is observed in the case of heating, that produces a marked dilatation of the interaction region. The distribution of the Stanton number shows that a strong amplification of the heat transfer occurs across the interaction, and the maximum values of thermal and dynamic loads are found in the case of cold wall. The analysis reveals that the fluctuating heat flux exhibits a strong intermittent behavior, characterized by scattered spots with extremely high values compared to the mean. Furthermore, the analogy between momentum and heat transfer, typical of compressible, wall-bounded, equilibrium turbulent flows does not apply for most part of the interaction domain. The pre-multiplied spectra of the wall heat flux do not show any evidence of the influence of the low-frequency shock motion, and the primary mechanism for the generation of peak heating is found to be linked with the turbulence amplification in the interaction region.Comment: submitted to PRFluid

Cisternostomy for Traumatic Brain Injury: A New Era Begins

Traumatic brain injury (TBI) is a major cause of death and disability especially in the young generations. In the United States TBI affects about 1.7 million people annually [1] and this number is higher in the developing countries. It is well known that TBI is associated to a primary and secondary brain injury. The first is without solution and depends on the impact. In surviving patients, what plays a critical role is the subsequent secondary injury since, without effective treatments, complex cascades will promote additional brain damage

Autophagy in Cell Fate and Diseases

Autophagy pathway has been one of the hot topics during the last decade. From a general notion about its cellular role, autophagy becomes a more sophisticated phenomenon with significant implications in cellular homeostasis. Consequently, autophagy represents an emerging new factor in human diseases. Despite its general task, the bulk degradation of cellular constituents during starvation settings, autophagy possesses important cross talk and interrelationships with several cellular processes such as apoptosis and senescence, among others. This entire panorama gives us a complex but exciting scenario. Consequently, with the aim of encompassing the whole spectrum, in this chapter, we review three main topics: autophagy as a cellular process; autophagy in cell fate; and autophagy in disease. We discuss the emerging role of selective type of autophagy to avoid apoptosis or necrosis and the novel relationship between autophagy and senescence to understand the real extent that autophagy pathway has over cell fate. Finally, we briefly describe the current trends on autophagy in human pancreatic diseases and its role in cancer cell metabolism

Anatomy and physiology of cisternostomy

Cisternostomy is defined as opening the basal cisterns to atmospheric pressure. This technique helps to reduce the intracranial pressure in severe head trauma as well as other conditions when the so-called sudden "brain swelling" troubles the surgeon. We elaborated the surgical anatomy of this procedure as well as the proposed physiology of how cisternostomy works. This novel technique may change the current trends in neurosurgery

Neutron Irradiation of Mg11B2 : From the Enhancement to the Suppression of Superconducting Properties

In this letter we present the effect of neutron irradiation up to fluences of 3.9 1019 n/cm2 on the superconducting properties of MgB2. In order to obtain a disorder structure homogeneously distributed, the experiment was carried out on bulk samples prepared with the 11B isotope. Up to fluences of 1018 n/cm2 the critical temperature is slightly diminished (36 K) and the superconducting properties are significantly improved; the upper critical field is increased from 13.5 T to 20.3 T at 12 K and the irreversibility field is doubled at 5 K. For larger neutron fluences the critical temperature is suppressed down to 12 K and the superconducting properties come out strongly degraded.Comment: 13 pages, 4 figures. Submitted to Appl.Phys.Let

Extended Skyrme interaction (II): ground state of nuclei and of nuclear matter

We study the effect of time-odd components of the Skyrme energy density functionals on the ground state of finite nuclei and in nuclear matter. The spin-density dependent terms, which have been recently proposed as an extension of the standard Skyrme interaction, are shown to change the total binding energy of odd-nuclei by only few tenths of keV, while the time-odd components of standard Skyrme interactions give an effect that is larger by one order of magnitude. The HFB-17 mass formula based on a Skyrme parametrization is adjusted including the new spin-density dependent terms. A comprehensive study of binding energies in the whole mass table of 2149 nuclei gives a root mean square (rms) deviation of 0.575 MeV between experimental data and the calculated results, which is slightly better than the original HFB-17 mass formula. From the analysis of the spin instabilities of nuclear matter, restrictions on the parameters governing the spin-density dependent terms are evaluated. We conclude that with the extended Skyrme interaction, the Landau parameters $G_0$ and $G_0^\prime$ could be tuned with a large flexibility without changing the ground-state properties in nuclei and in nuclear matter.Comment: 18 pages, 4 tables, 6 figure