Gross-Neveu Models, Nonlinear Dirac Equations, Surfaces and Strings

Recent studies of the thermodynamic phase diagrams of the Gross-Neveu model (GN2), and its chiral cousin, the NJL2 model, have shown that there are phases with inhomogeneous crystalline condensates. These (static) condensates can be found analytically because the relevant Hartree-Fock and gap equations can be reduced to the nonlinear Schr\"odinger equation, whose deformations are governed by the mKdV and AKNS integrable hierarchies, respectively. Recently, Thies et al have shown that time-dependent Hartree-Fock solutions describing baryon scattering in the massless GN2 model satisfy the Sinh-Gordon equation, and can be mapped directly to classical string solutions in AdS3. Here we propose a geometric perspective for this result, based on the generalized Weierstrass spinor representation for the embedding of 2d surfaces into 3d spaces, which explains why these well-known integrable systems underlie these various Gross-Neveu gap equations, and why there should be a connection to classical string theory solutions. This geometric viewpoint may be useful for higher dimensional models, where the relevant integrable hierarchies include the Davey-Stewartson and Novikov-Veselov systems.Comment: 27 pages, 1 figur

The ρ(1S,2S)\rho(1S,2S), ψ(1S,2S)\psi(1S,2S), Υ(1S,2S)\Upsilon(1S,2S) and ψt(1S,2S)\psi_t(1S,2S) mesons in a double pole QCD Sum Rule

We use the method of double pole QCD sum rule which is basically a fit with two exponentials of the correlation function, where we can extract the masses and decay constants of mesons as a function of the Borel mass. We apply this method to study the mesons: $\rho(1S,2S)$, $\psi(1S,2S)$, $\Upsilon(1S,2S)$ and $\psi_t(1S,2S)$. We also present predictions for the toponiuns masses $\psi_t(1S,2S)$ of m(1S)=357 GeV and m(2S)=374 GeV.Comment: 14 pages, 11 figures in Braz J Phys (2016

Gravitational Waves from Gravitational Collapse

Gravitational wave emission from the gravitational collapse of massive stars has been studied for more than three decades. Current state of the art numerical investigations of collapse include those that use progenitors with realistic angular momentum profiles, properly treat microphysics issues, account for general relativity, and examine non--axisymmetric effects in three dimensions. Such simulations predict that gravitational waves from various phenomena associated with gravitational collapse could be detectable with advanced ground--based and future space--based interferometric observatories.Comment: 68 pages including 13 figures; revised version accepted for publication in Living Reviews in Relativity (http://www.livingreviews.org

An overview of tissue engineering approaches for management of spinal cord injuries

Severe spinal cord injury (SCI) leads to devastating neurological deficits and disabilities, which necessitates spending a great deal of health budget for psychological and healthcare problems of these patients and their relatives. This justifies the cost of research into the new modalities for treatment of spinal cord injuries, even in developing countries. Apart from surgical management and nerve grafting, several other approaches have been adopted for management of this condition including pharmacologic and gene therapy, cell therapy, and use of different cell-free or cell-seeded bioscaffolds. In current paper, the recent developments for therapeutic delivery of stem and non-stem cells to the site of injury, and application of cell-free and cell-seeded natural and synthetic scaffolds have been reviewed

QCD and strongly coupled gauge theories : challenges and perspectives

We highlight the progress, current status, and open challenges of QCD-driven physics, in theory and in experiment. We discuss how the strong interaction is intimately connected to a broad sweep of physical problems, in settings ranging from astrophysics and cosmology to strongly coupled, complex systems in particle and condensed-matter physics, as well as to searches for physics beyond the Standard Model. We also discuss how success in describing the strong interaction impacts other fields, and, in turn, how such subjects can impact studies of the strong interaction. In the course of the work we offer a perspective on the many research streams which flow into and out of QCD, as well as a vision for future developments.Peer reviewe

[Synthesis, Structure and Some Biochemical-properties of 3'-branched Thymidines and Their 5'-phosphate Derivatives]

A full scheme of synthesizing 3'-C-methyl-2'-deoxynucleosides and 3'-C-methylidene-28,3'-dideoxythymidine has been developed by using 2-deoxyribose. The stereoselectivity of the Grignard reagent's attachment to 2-deoxyfuranose 3-ulosides determined by the substitute configuration at Cl and the condensation stereoselectivity of 3-C-methyl-2-deoxyfuranosides with silylated thymine dependent on the configuration of the hydroxyl or-OBz group at C3 have been studied. The structure of the resultant compounds has been evidenced by H-1 and C-13 NMR, UV spectroscopies and C, H, and N analysis. The C2'-endo-C1-exo-conformation, the anti-conformation of the thymine base in relation to the glycoside bond and the gosh+-conformation in relation to the C4'-C5' bond are characteristic of the structure of 3'-C-methyl-2'-deoxythymidine in the crystal. 3'-C-Metyl-2'-deoxythymidine-5'-triphosphate exhibited the properties of the competitive inhibitor against 2'-deoxythimidine 5'-triphosphate in the synthesis of DNA catalyzed by various DNA-polymerases and reverse transcriptases. But none of these enzymes incorporated this compound into the growing DNA chain. At the same time 3'-C-methylidene-2',3'-dideoxythymidine-5'-triphosphate was incorporated into the 3'-end of the chain of DNA catalyzed by HIV reverse transcriptase, though the latter having a low efficacy. 3'-C-Methyl-2'-deoxythymidine failed to suppress HIV-1 production in the cultured MT-4 cells, its 5'-phosphite exhibiting a low activity under the same conditions