Newton Law in DGP Brane-World with Semi-Infinite Extra Dimension

Newton potential for DGP brane-world scenario is examined when the extra dimension is semi-infinite. The final form of the potential involves a self-adjoint extension parameter $\alpha$, which plays a role of an additional mass (or distance) scale. The striking feature of Newton potential in this setup is that the potential behaves as seven-dimensional in long range when $\alpha$ is nonzero. For small $\alpha$ there is an intermediate range where the potential is five-dimensional. Five-dimensional Newton constant decreases with increase of $\alpha$ from zero. In the short range the four-dimensional behavior is recovered. The physical implication of this result is discussed in the context of the accelerating behavior of universe.Comment: 13 pages, no figur

Newton Law on the Generalized Singular Brane with and without 4d Induced Gravity

Newton law arising due to the gravity localized on the general singular brane embedded in $AdS_5$ bulk is examined in the absence or presence of the 4d induced Einstein term. For the RS brane, apart from the subleading correction, Newton potential obeys 4d-type and $5d$-type gravitational law at long- and short-ranges if it were not for the induced Einstein term. The 4d induced Einstein term generates an intermediate range at short distance, in which the $5d$ Newton potential $1/r^2$ emerges. For Neumann brane the long-range behavior of Newton potential is exponentially suppressed regardless of the existence of the induced Einstein term. For Dirichlet brane the expression of Newton potential is dependent on the renormalized coupling constant $v^{ren}$. At particular value of $v^{ren}$ Newton potential on Dirichlet brane exhibits a similar behavior to that on RS brane. For other values the long-range behavior of Newton potential is exponentially suppressed as that in Neumann brane.Comment: 27 pages, 2 postscript figures included V1 figures are improved and few comments are added for further discussion. version to appear in NP

Electron transport in nanotube--molecular wire hybrids

We study contact effects on electron transport across a molecular wire sandwiched between two semi-infinite (carbon) nanotube leads as a model for nanoelectrodes. Employing the Landauer scattering matrix approach we find that the conductance is very sensitive to parameters such as the coupling strength and geometry of the contact. The conductance exhibits markedly different behavior in the two limiting scenarios of single contact and multiple contacts between the molecular wire and the nanotube interfacial atoms. In contrast to a single contact the multiple-contact configuration acts as a filter selecting single transport channels. It exhibits a scaling law for the conductance as a function of coupling strength and tube diameter. We also observe an unusual narrow-to-broad-to-narrow behavior of conductance resonances upon decreasing the coupling.Comment: 4 pages, figures include

Scaling analysis of electron transport through metal-semiconducting carbon nanotube interfaces: Evolution from the molecular limit to the bulk limit

We present a scaling analysis of electronic and transport properties of metal-semiconducting carbon nanotube interfaces as a function of the nanotube length within the coherent transport regime, which takes fully into account atomic-scale electronic structure and three-dimensional electrostatics of the metal-nanotube interface using a real-space Green's function based self-consistent tight-binding theory. As the first example, we examine devices formed by attaching finite-size single-wall carbon nanotubes (SWNT) to both high- and low- work function metallic electrodes through the dangling bonds at the end. We analyze the nature of Schottky barrier formation at the metal-nanotube interface by examining the electrostatics, the band lineup and the conductance of the metal-SWNT molecule-metal junction as a function of the SWNT molecule length and metal-SWNT coupling strength. We show that the confined cylindrical geometry and the atomistic nature of electronic processes across the metal-SWNT interface leads to a different physical picture of band alignment from that of the planar metal-semiconductor interface. We analyze the temperature and length dependence of the conductance of the SWNT junctions, which shows a transition from tunneling- to thermal activation-dominated transport with increasing nanotube length. The temperature dependence of the conductance is much weaker than that of the planar metal-semiconductor interface due to the finite number of conduction channels within the SWNT junctions. We find that the current-voltage characteristics of the metal-SWNT molecule-metal junctions are sensitive to models of the potential response to the applied source/drain bias voltages.Comment: Minor revision to appear in Phys. Rev. B. Color figures available in the online PRB version or upon request to: [email protected]

On Aharonov-Casher bound states

In this work bound states for the Aharonov-Casher problem are considered. According to Hagen's work on the exact equivalence between spin-1/2 Aharonov-Bohm and Aharonov-Casher effects, is known that the $\boldsymbol{\nabla}\cdot\mathbf{E}$ term cannot be neglected in the Hamiltonian if the spin of particle is considered. This term leads to the existence of a singular potential at the origin. By modeling the problem by boundary conditions at the origin which arises by the self-adjoint extension of the Hamiltonian, we derive for the first time an expression for the bound state energy of the Aharonov-Casher problem. As an application, we consider the Aharonov-Casher plus a two-dimensional harmonic oscillator. We derive the expression for the harmonic oscillator energies and compare it with the expression obtained in the case without singularity. At the end, an approach for determination of the self-adjoint extension parameter is given. In our approach, the parameter is obtained essentially in terms of physics of the problem.Comment: 11 pages, matches published versio

Sotagliflozin in combination with optimized insulin therapy in adults with type 1 diabetes: The North American in Tandem1 study

OBJECTIVE: Evaluate the efficacy and safety of the dual sodium-glucose cotransporter 1 (SGLT1) and SGLT2 inhibitor sotagliflozin in combination with optimized insulin in type 1 diabetes (T1D). RESEARCH DESIGN AND METHODS: The in Tandem1 trial, a double-blind, 52-week phase 3 trial, randomized North American adults with T1D to placebo (n = 268), sotagliflozin 200 mg (n = 263), or sotagliflozin 400mg(n =262) after6 weeks ofinsulin optimization. The primary end point was HbA1c change from baseline at 24 weeks. HbA1c, weight, and safety were also assessed through 52 weeks. RESULTS: From a mean baseline of 7.57%, placebo-adjusted HbA1c reductions were 0.36% and 0.41% with sotagliflozin 200 and 400 mg, respectively, at 24 weeks and 0.25% and 0.31% at 52 weeks (all P < 0.001). Among patients with a baseline HbA1c ≥7.0%, an HbA1c <7% was achieved by 15.7%, 27.2%, and 40.3% of patients receiving placebo, sotagliflozin 200 mg, and sotagliflozin 400 mg, respectively (P ≤ 0.003 vs. placebo) at 24 weeks. At 52 weeks, mean treatment differences between sotagliflozin 400 mg and placebo were 21.08 mmol/L for fasting plasma glucose, 24.32 kg for weight, and 215.63% for bolus insulin dose and 211.87% for basal insulin dose (all P < 0.001). Diabetes Treatment Satisfaction Questionnaire scores increased significantly by 2.5 points with sotagliflozin versus placebo (P < 0.001) at 24 weeks. Genital mycotic infections and diarrhea occurred more frequently with sotagliflozin. Adjudicated diabetic ketoacidosis (DKA) occurred in 9 (3.4%) and 11 (4.2%) patients receiving sotagliflozin 200 and 400 mg, respectively, and in 1 (0.4%) receiving placebo. Severe hypoglycemia occurred in 17 (6.5%) patients from each sotagliflozin group and 26 (9.7%) patients receiving placebo. CONCLUSIONS: In a 1-year T1D study, sotagliflozin combined with optimized insulin therapy was associated with sustained HbA1c reduction, weight loss, lower insulin dose, fewer episodes of severe hypoglycemia, improved patient-reported outcomes, and more DKA relative to placebo (ClinicalTrials.gov, NCT02384941)

Green function techniques in the treatment of quantum transport at the molecular scale

The theoretical investigation of charge (and spin) transport at nanometer length scales requires the use of advanced and powerful techniques able to deal with the dynamical properties of the relevant physical systems, to explicitly include out-of-equilibrium situations typical for electrical/heat transport as well as to take into account interaction effects in a systematic way. Equilibrium Green function techniques and their extension to non-equilibrium situations via the Keldysh formalism build one of the pillars of current state-of-the-art approaches to quantum transport which have been implemented in both model Hamiltonian formulations and first-principle methodologies. We offer a tutorial overview of the applications of Green functions to deal with some fundamental aspects of charge transport at the nanoscale, mainly focusing on applications to model Hamiltonian formulations.Comment: Tutorial review, LaTeX, 129 pages, 41 figures, 300 references, submitted to Springer series "Lecture Notes in Physics

Equine Protozoal Myeloencephalitis: An Updated Consensus Statement with a Focus on Parasite Biology, Diagnosis, Treatment, and Prevention

Equine protozoal myeloencephalitis (EPM) remains an important neurologic disease of horses. There are no pathognomonic clinical signs for the disease. Affected horses can have focal or multifocal central nervous system (CNS) disease. EPM can be difficult to diagnose antemortem. It is caused by either of 2 parasites, Sarcocystis neurona and Neospora hughesi, with much less known about N. hughesi. Although risk factors such as transport stress and breed and age correlations have been identified, biologic factors such as genetic predispositions of individual animals, and parasite-specific factors such as strain differences in virulence, remain largely undetermined. This consensus statement update presents current published knowledge of the parasite biology, host immune response, disease pathogenesis, epidemiology, and risk factors. Importantly, the statement provides recommendations for EPM diagnosis, treatment, and prevention