Brane Gas Cosmology, M-theory and Little String Theory

We generalize the Brane Gas Cosmological Scenario to M-theory degrees of freedom, namely $M5$ and $M2$ branes. Without brane intersections, the Brandenberger Vafa(BV) arguments applied to M-theory degrees of freedom generically predict a large 6 dimensional spacetime. We show that intersections of $M5$ and $M2$ branes can instead lead to a large 4 dimensional spacetime. One dimensional intersections in 11D is related to (2,0) little strings (LST) on NS5 branes in type IIA. The gas regime of membranes in M-theory corresponds to the thermodynamics of LST obtained from holography. We propose a mechanism whereby LST living on the worldvolume of NS5 (M5)-branes wrapping a five dimensional torus, annihilate most efficiently in 3+1 dimensions leading to a large 3+1 dimensional spacetime. We also show that this picture is consistent with the gas approximation in M-theory.Comment: 8 page

Entanglement of a Single Spin-1 Object: An Example of Ubiquitous Entanglement

Using a single spin-1 object as an example, we discuss a recent approach to quantum entanglement. The key idea of the approach consists in presetting of basic observables in the very definition of quantum system. Specification of basic observables defines the dynamic symmetry of the system. Entangled states of the system are then interpreted as states with maximal amount of uncertainty of all basic observables. The approach gives purely physical picture of entanglement. In particular, it separates principle physical properties of entanglement from inessential. Within the model example under consideration, we show relativity of entanglement with respect to dynamic symmetry and argue existence of single-particle entanglement. A number of physical examples are considered.Comment: 12 pages, 2 figure : title has been changed, paper is re-organized, new section "Violation of Bell-type condition by single spin-1" is adde

On quantization of singular varieties and applications to D-branes

We calculate the ring of differential operators on some singular affine varieties (intersecting stacks, a point on a singular curve or an orbifold). Our results support the proposed connection of the ring of differential operators with geometry of D-branes in (bosonic) string theory. In particular, the answer does know about the resolution of singularities in accordance with the string theory predictions.Comment: LaTeX2e, 17 pages, misprints correcte

Random Mass Dirac Fermions in Doped Spin-Peierls and Spin-Ladder systems: One-Particle Properties and Boundary Effects

Quasi-one-dimensional spin-Peierls and spin-ladder systems are characterized by a gap in the spin-excitation spectrum, which can be modeled at low energies by that of Dirac fermions with a mass. In the presence of disorder these systems can still be described by a Dirac fermion model, but with a random mass. Some peculiar properties, like the Dyson singularity in the density of states, are well known and attributed to creation of low-energy states due to the disorder. We take one step further and study single-particle correlations by means of Berezinskii's diagram technique. We find that, at low energy $\epsilon$, the single-particle Green function decays in real space like $G(x,\epsilon) \propto (1/x)^{3/2}$. It follows that at these energies the correlations in the disordered system are strong -- even stronger than in the pure system without the gap. Additionally, we study the effects of boundaries on the local density of states. We find that the latter is logarithmically (in the energy) enhanced close to the boundary. This enhancement decays into the bulk as $1/\sqrt{x}$ and the density of states saturates to its bulk value on the scale $L_\epsilon \propto \ln^2 (1/\epsilon)$. This scale is different from the Thouless localization length $\lambda_\epsilon\propto\ln (1/\epsilon)$. We also discuss some implications of these results for the spin systems and their relation to the investigations based on real-space renormalization group approach.Comment: 26 pages, LaTex, 9 PS figures include

Optimal observables for new-physics search at LEP2

New observables \sigma_\pm for the process e^+e^-\to\mu^+\mu^- allow one to get more direct information on additional Z' boson effects than what is obtained from the canonical ones, \sigma and A_{FB}. Their deviations from the Standard Model predictions have very specific energy dependences, which are precisely determined by SM parameters. At energies varying from TRISTAN to LEP2, one can uniquely predict the signs of \Delta\sigma_{\pm} induced by a Z' as well as the locations of their extrema and zeros. This unambiguous energy correlation could be quite useful in distinguishing effects due to Z' exchange from those caused by other new physics sources. Furthermore, there are two energy points, \sqrt{s_{+}}\simeq 78 GeV and \sqrt{s_{-}}\simeq 113 GeV, where the SM quantities \sigma_\pm^{SM} as well as the deviations \Delta\sigma_{\pm} attain their minimum values or vanish. These points could be very favourable for a search for new physics beyond the SM and beyond Z' effects.Comment: LaTeX2e + 7 eps figures. References added, version to appear in Phys. Lett.

Analysis of the Threshold Effect of Government Expenditure and Commercial Bank Credit on Agricultural Output in Nigeria

This study empirically investigated the threshold effect of government expenditure and commercial bank credit on agricultural performance in Nigeria spanning 1986 to 2021. The study used the Threshold Autoregression (TAR) analysis to carry out the analysis. The result of the TAR regression established a threshold value of N390.01 billion for government agricultural expenditure. The TAR regression established a linear relationship between government expenditure and agricultural performance in Nigeria, thus, a positive threshold effect of 2% and 22% below and above the threshold value respectively was established by the TAR regression. Similarly, an asymmetric inverted U-shaped relationship exists between commercial bank credit to the agricultural sector and the performance of the agricultural sector in Nigeria. It found a threshold value of commercial bank credit to the agricultural sector at N610.15 billion; stating that below this threshold, commercial bank credit to the agricultural sector has a positive and significant effect of 51% on the performance of the agricultural sector in Nigeria. However, above this threshold, commercial bank credit adversely affect the performance of the agricultural sector, reducing the sector’s performance by 6%. Based on these findings, this study recommends that commercial bank credit to the agricultural sector should be kept within the established threshold level. Furthermore, to maximize the performance of the agricultural sector, the study recommends the allocation of additional funds to the agricultural sector by the government. Keywords: Government Expenditure, Commercial Banks Credits, Agricultural Output, Threshold Regression. Jel Codes: H50,G21,Q10,C14 DOI: 10.7176/JESD/13-18-06 Publication date:September 30th 202

Anchor Borrower Programme on Agricultural Commodity Price and Employment Generation in Kebbi State, Nigeria

Low investment in the agricultural sector, as well as problem of financing are among the major challenges hindering farmers in the rural areas engaging in mechanized farming that might increase food supply, and thereby checking the agricultural commodity prices, and possibly creating more job opportunity in the agricultural sector. In an effort to meet the food supply for the growing population of the country, the government introduced various policies aimed at achieving self-sufficiency in basic food supply, among these policies is the Anchor Borrower Programme. This study examines the impact of Anchor Borrower Program on agricultural commodity price and employment generation in Kebbi state, Nigeria. Data were collected through interview and structured questionnaire administered to a sample of 400 farmers in Argungu L.G.A, of which 360 questionnaire were correctly filled and returned. A multiple regression analysis was used to analyse the data. The results reveal that Anchor Borrower Programmes (ABP) supports for farmer have a positive and statistically significant impact on agricultural commodity price (ACP) and employment generation (EMPG) in agricultural sector in Kebbi state, particularly in Argungu LGA. Based on the findings of this study, it is recommended that anchor borrower programme policy in Nigeria should be encouraged and subjected to periodic review so as to provide more platforms for employment generation and stabilize agricultural commodity price in Kebbi state, particularly in Argungu LGA

Suppression of Zeeman Relaxation in Cold Collisions of 2P1/2^2P_{1/2} Atoms

We present a combined experimental and theoretical study of angular momentum depolarization in cold collisions of $^2P$ atoms in the presence of an external magnetic field. We show that collision-induced Zeeman relaxation of Ga$^2P_{1/2}$ and In $^2P_{1/2}$ atoms in cold $^4$He gas is dramatically suppressed compared to atoms in $^2P_{3/2}$ states. Using rigorous quantum-scattering calculations based on ab initio interaction potentials, we demonstrate that Zeeman transitions in collisions of atoms in $^2P$ electronic states occur via couplings to the $^2P_{3/2}$ state induced by the anisotropy of the interaction potential. Our results suggest the feasibility of sympatheticthetic cooling and magnetic trapping of $^2P_{1/2}$-state atoms, such as halogens, thereby opening up exciting areas of research in precision spectroscopy and cold-controlled chemistry.Physic

An integrated approach to modelling the fluid-structure interaction of a collapsible tube

The well known collapsible tube experiment was conducted to obtain flow, pressure and materials property data for steady state conditions. These were then used as the boundary conditions for a fully coupled fluid-structure interaction (FSI) model using a propriety computer code, LS-DYNA. The shape profiles for the tube were also recorded. In order to obtain similar collapse modes to the experiment, it was necessary to model the tube flat, and then inflate it into a circular profile, leaving residual stresses in the walls. The profile shape then agreed well with the experimental ones. Two departures from the physical properties were required to reduce computer time to an acceptable level. One of these was the lowering of the speed of sound by two orders of magnitude which, due to the low velocities involved, still left the mach number below 0.2. The other was to increase the thickness of the tube to prevent the numerical collapse of elements. A compensation for this was made by lowering the Young's modulus for the tube material. Overall the results are qualitatively good. They give an indication of the power of the current FSI algorithms and the need to combine experiment and computer models in order to maximise the information that can be extracted both in terms of quantity and quality

Rehabilitation of the upper extremity and basic activities of daily living in the first month after ischemic stroke: an international cohort comparison study

Inpatient rehabilitation has been traditionally employed in developed countries, while in developing countries, outpatient rehabilitation is the rule. The purpose of this study was to compare the patterns of recovery of upper extremity (UE) function, global impairment and independence in activities of daily living (ADL) during the first month after ischemic stroke in inpatient (United States) and outpatient (Brazil) rehabilitation settings