The full set of cnc_n-invariant factorized SS-matrices

We use the method of the tensor product graph to construct rational (Yangian invariant) solutions of the Yang-Baxter equation in fundamental representations of $c_n$ and thence the full set of $c_n$-invariant factorized $S$-matrices. Brief comments are made on their bootstrap structure and on Belavin's scalar Yangian conserved charges.Comment: 10p

Spin-dependent tunneling in magnetic tunnel junctions

The phenomenon of electron tunneling has been known since the advent of quantum mechanics, but continues to enrich our understanding of many fields of physics, as well as creating sub-fields on its own. Spin-dependent tunneling in magnetic tunnel junctions (MTJs) has recently aroused enormous interest and has developed in a vigorous field of research. The large tunneling magnetoresistance (TMR) observed in MTJs garnered much attention due to possible applications in non-volatile random access memories and next-generation magnetic field sensors. This led to a number of fundamental questions regarding the phenomenon of spindependent tunneling. In this review article we present an overview of this field of research. We discuss various factors that control the spin polarization and magnetoresistance in magnetic tunnel junctions. Starting from early experiments on spin-dependent tunneling and their interpretation, we consider thereafter recent experiments and models, which highlight the role of the electronic structure of the ferromagnets, the insulating layer and the ferromagnet/insulator interfaces. We also discuss the role of disorder in the barrier and in the ferromagnetic electrodes and their influence on TMR

Spin-dependent tunneling in magnetic tunnel junctions

The phenomenon of electron tunneling has been known since the advent of quantum mechanics, but continues to enrich our understanding of many fields of physics, as well as creating sub-fields on its own. Spin-dependent tunneling in magnetic tunnel junctions (MTJs) has recently aroused enormous interest and has developed in a vigorous field of research. The large tunneling magnetoresistance (TMR) observed in MTJs garnered much attention due to possible applications in non-volatile random access memories and next-generation magnetic field sensors. This led to a number of fundamental questions regarding the phenomenon of spindependent tunneling. In this review article we present an overview of this field of research. We discuss various factors that control the spin polarization and magnetoresistance in magnetic tunnel junctions. Starting from early experiments on spin-dependent tunneling and their interpretation, we consider thereafter recent experiments and models, which highlight the role of the electronic structure of the ferromagnets, the insulating layer and the ferromagnet/insulator interfaces. We also discuss the role of disorder in the barrier and in the ferromagnetic electrodes and their influence on TMR

Quantum statistical mechanics of gases in terms of dynamical filling fractions and scattering amplitudes

We develop a finite temperature field theory formalism in any dimension that has the filling fractions as the basic dynamical variables. The formalism efficiently decouples zero temperature dynamics from the quantum statistical sums. The zero temperature `data' is the scattering amplitudes. A saddle point condition leads to an integral equation which is similar in spirit to the thermodynamic Bethe ansatz for integrable models, and effectively resums infinite classes of diagrams. We present both relativistic and non-relativistic versions

Witten's Vertex Made Simple

The infinite matrices in Witten's vertex are easy to diagonalize. It just requires some SL(2,R) lore plus a Watson-Sommerfeld transformation. We calculate the eigenvalues of all Neumann matrices for all scale dimensions s, both for matter and ghosts, including fractional s which we use to regulate the difficult s=0 limit. We find that s=1 eigenfunctions just acquire a p term, and x gets replaced by the midpoint position.Comment: 24 pages, 2 figures, RevTeX style, typos correcte

A central extension of \cD Y_{\hbar}(\gtgl_2) and its vertex representations

A central extension of \cD Y_{\hbar}(\gtgl_2) is proposed. The bosonization of level $1$ module and vertex operators are also given.Comment: 10 pages, AmsLatex, to appear in Lett. in Math. Phy

Boundary bound states and boundary bootstrap in the sine-Gordon model with Dirichlet boundary conditions.

We present a complete study of boundary bound states and related boundary S-matrices for the sine-Gordon model with Dirichlet boundary conditions. Our approach is based partly on the bootstrap procedure, and partly on the explicit solution of the inhomogeneous XXZ model with boundary magnetic field and of the boundary Thirring model. We identify boundary bound states with new ``boundary strings'' in the Bethe ansatz. The boundary energy is also computed.Comment: 25 pages, harvmac macros Report USC-95-001

Descent Relations and Oscillator Level Truncation Method

We reexamine the oscillator level truncation method in the bosonic String Field Theory (SFT) by calculation the descent relation =Z_3<V_2|. For the ghost sector we use the fermionic vertices in the standard oscillator basis. We propose two new schemes for calculations. In the first one we assume that the insertion satisfies the overlap equation for the vertices and in the second one we use the direct calculations. In both schemes we get the correct structures of the exponent and pre-exponent of the vertex <V_2|, but we find out different normalization factors Z_3.Comment: 21 pages, 10 figures, Late

Tolerance and efficacy of preventive gastrostomy feeding in pediatric oncology

BackgroundMalnutrition in pediatric oncology remains underestimated, although having a negative impact on outcome. Enteral nutrition (EN) using percutaneous endoscopic gastrostomy (PEG) may prevent or reverse malnutrition consequences. We aimed to evaluate both efficacy and safety of early EN during tumors treatment in children. Procedures Medical records of pediatric patients having a PEG tube inserted between 1995 and 2009 were retrospectively reviewed. We compared type and incidence of complications in Group 1, including 74 patients suffering from cancer, and control Group 2, including 57 patients with neurological impairment. Efficacy of EN was evaluated through nutritional parameters [Z-scores weight for height (W/H) and height for age (H/A)], post-operative complications and relapse rates. Statistical significance was set for P &lt; 0.05. Results PEG tolerance was similar in both groups, as shown by comparable complication rates (62% vs. 76%, NS). EN allowed improvement or stabilization of Z-score W/H in 76% of oncologic patients. The final height loss was lower (−0.5 vs. −1.2 SD of Z-scores H/A) when EN was started at the beginning of the oncologic treatment. In bone tumors, EN prevented weight loss during chemotherapy, and tended to lessen surgical complications, relapses and deaths. Conclusions Early gastrostomy feeding represents a relatively safe way to prevent malnutrition in children with cancer, and might play a role in bone tumors oncological outcome. Further prospective studies are needed to confirm these results and assess the impact of EN and PEG on quality of life

Kappa symmetric OSp(2|2) WZNW model

We construct a kappa symmetric WZNW model for the OSp(2|2) supergroup, whose bosonic part is AdS3xS1 space. The field equation gives the chiral current conservation and the right/left factorization is shown after the kappa symmetry is fixed. The right-moving modes contain both bosons and fermions while the left-moving modes contain only bosons.Comment: 18 pages; reference and comments added, version to appear in JHE