Traversable Wormholes Construction in 2+1 Dimensions

We study traversable Lorentzian wormholes in the three-dimensional low energy string theory by adding some matter source involving a dilaton field. It will be shown that there are two-different types of wormhole solutions such as BTZ and black string wormholes depending on the dilaton backgrounds, respectively. We finally obtain the desirable solutions which confine exotic matter near the throat of wormhole by adjusting NS charge.Comment: 12 pages, 4 figures, JHEP style, one reference adde

Research performance of teams in Business and Management: The impact of team size, knowledge diversity and international diversity

Despite inherent differences across disciplines, collaboration in general and larger teams of co-authors in particular, are prevalent strategies to increase research performance via academic publications. We take a more fine-grained view of this relationship by distinguishing between two dimensions of research performance, namely impact (i.e., subsequent citations of a paper) and prestige (i.e., top academic journals). Different from prior literature, we argue that there are both benefits and pitfalls in having larger teams, and these trade-offs will affect differently the impact and prestige of academic research. Specifically, we propose that while team size will enhance linearly the impact of a paper, it will contribute in a non-linear fashion to its prestige. Furthermore, these relationships will be moderated by the knowledge and international diversity of the team. We test these hypotheses using bibliometric data on more than 40,000 publications between 1994 and 2013 papers across 21 sub-fields within the realm of Business and Management. Our results broadly support our theoretical assertions. We discuss some practical implications for assessing and stimulating the research performance of academics in business schools

Compressibility of a two-dimensional hole gas in tilted magnetic field

We have measured compressibility of a two-dimensional hole gas in p-GaAs/AlGaAs heterostructure, grown on a (100) surface, in the presence of a tilted magnetic field. It turns out that the parallel component of magnetic field affects neither the spin splitting nor the density of states. We conclude that: (a) g-factor in the parallel magnetic field is nearly zero in this system; and (b) the level of the disorder potential is not sensitive to the parallel component of the magnetic field

Metal-insulator transition in disordered 2DEG including temperature effects

We calculate self-consistently the mutual dependence of electron correlations and electron-defect scattering for a two dimensional electron gas at finite temperature. We employ an STLS approach to calculate the electron correlations while the electron scattering rate off Coulombic impurities and surface roughness is calculated using self-consistent current-relaxation theory. The methods are combined and self-consistently solved. We discuss a metal-insulator transition for a range of disorder levels and electron densities. Our results are in good agreement with recent experimental observations.Comment: 4 pages, RevTeX + epsf, 5 figure

Dry needling of trigger points with and without paraspinal needling in myofascial pain syndromes in elderly patients

ABSTRACT Objectives: To compare the efficacies of dry needling of trigger points (TrPs) with and without paraspinal needling in myofascial pain syndrome of elderly patients. Design: Single-blinded, randomized controlled trial. Subjects: Forty Interventions: Eighteen (18) subjects were treated with dry needling of all the TrPs only and another 22 with additional paraspinal needling on days 0, 7, and 14. Results: At 4-week follow-up the results were as follows: (1) TrP and paraspinal dry needling resulted in more continuous subjective pain reduction than TrP dry needling only; (2) TrP and paraspinal dry needling resulted in significant improvements on the geriatric depression scale but TrP dry needling only did not; (3) TrP and paraspinal dry needling resulted in improvements of all the cervical range of motions but TrP dry needling only did not in extensional cervical range of motion; and (4) no cases of gross hemorrhage were noted. Conclusions: TrP and paraspinal dry needling is suggested to be a better method than TrP dry needling only for treating myofascial pain syndrome in elderly patients. 61

Orientational pinning and transverse voltage: Simulations and experiments in square Josephson junction arrays

We study the dependence of the transport properties of square Josephson Junctions arrays with the direction of the applied dc current, both experimentally and numerically. We present computational simulations of current-voltage curves at finite temperatures for a single vortex in the array ($Ha^2/\Phi_0=f=1/L^2$), and experimental measurements in $100\times1000$ arrays under a low magnetic field corresponding to $f\approx0.02$. We find that the transverse voltage vanishes only in the directions of maximum symmetry of the square lattice: the [10] and [01] direction (parallel bias) and the [11] direction (diagonal bias). For orientations different than the symmetry directions, we find a finite transverse voltage which depends strongly on the angle $\phi$ of the current. We find that vortex motion is pinned in the [10] direction ($\phi=0$), meaning that the voltage response is insensitive to small changes in the orientation of the current near $\phi=0$. We call this phenomenon orientational pinning. This leads to a finite transverse critical current for a bias at $\phi=0$ and to a transverse voltage for a bias at $\phi\not=0$. On the other hand, for diagonal bias in the [11] direction the behavior is highly unstable against small variations of $\phi$, leading to a rapid change from zero transverse voltage to a large transverse voltage within a few degrees. This last behavior is in good agreement with our measurements in arrays with a quasi-diagonal current drive.Comment: 9 pages, 9 figure

Reunion of random walkers with a long range interaction: applications to polymers and quantum mechanics

We use renormalization group to calculate the reunion and survival exponents of a set of random walkers interacting with a long range $1/r^2$ and a short range interaction. These exponents are used to study the binding-unbinding transition of polymers and the behavior of several quantum problems.Comment: Revtex 3.1, 9 pages (two-column format), 3 figures. Published version (PRE 63, 051103 (2001)). Reference corrections incorporated (PRE 64, 059902 (2001) (E

The effectiveness of the stabilization/solidification process on the leachability and toxicity of the tannery sludge chromium

[EN] A stabilization/solidification (S/S) process by using cement was applied to tannery sludge in order to find a safer way of landfilling this waste. The effects of three parameters on the process effectiveness were analysed in terms of leachate toxicity and chromium retention (%). The parameters studied were the relative amount of added water (30e50 wt.%), cement (10e60 wt.% in the solid components), and the use of three different types of cement (clinker with additions of limestone, with additions of limestone and fly ashes, and with additions of pozzolans). Statistical analysis performed by variance analysis and categorical multifactorial tests reveals that all the studied parameters significantly influence the effectiveness of the process. Results showed that chromium retention decreases as the relative amount of cement and water increases, probably due to additional chromium provided by cement and increased in the porosity of the mixtures. Leachate toxicity showed the same minimum value for mixtures with 30% or 40% cement, depending on the type of cement, showing that clinker is the main material responsible for the process effectiveness, and additives (pozzolans or fly ashes) do not improve it. The volume increase is lower as less sludge is replaced by cement and the relative amount of water decreases, and for the cement without additions of fly ashes or pozzolans. Therefore, the latter seems to be the most appropriate cement in spite of being more expensive. This is due to the fact that the minimum toxicity value is achieved with a lower amount of cement; and moreover, the volume increase in the mixtures is lower, minimizing the disposal cost to a landfill.The authors wish to express their gratitude to the tannery facility INCUSA, S.A., to the cement facility CEMEX ESPAÑA, S.A. and to Carles Martínez for his translation assistance.Montañés Sanjuan, MT.; Sánchez Tovar, R.; Roux, MSB. (2014). The effectiveness of the stabilization/solidification process on the leachability and toxicity of the tannery sludge chromium. Journal of Environmental Management. 143:71-79. doi:10.1016/j.jenvman.2014.04.026S717914