Quantum Phase Transition, O(3) Universality Class and Phase Diagram of Spin-1/2 Heisenberg Antiferromagnet on Distorted Honeycomb Lattice: A Tensor Renormalization Group Study

The spin-1/2 Heisenberg antiferromagnet on the distorted honeycomb (DHC) lattice is studied by means of the tensor renormalization group method. It is unveiled that the system has a quantum phase transition of second-order between the gapped quantum dimer phase and a collinear Neel phase at the critical point of coupling ratio \alpha_{c} = 0.54, where the quantum critical exponents \nu = 0.69(2) and \gamma = 1.363(8) are obtained. The quantum criticality is found to fall into the O(3) universality class. A ground-state phase diagram in the field-coupling ratio plane is proposed, where the phases such as the dimer, semi-classical Neel, and polarized phases are identified. A link between the present spin system to the boson Hubbard model on the DHC lattice is also discussed.Comment: 6 pages, 5 figures, published in Phys. Rev.

Genetic Algorithms Based Economic Dispatch with Application to Coordination of Nigerian Thermal Power Plants

The main focus of this paper is on the application of genetic algorithm (GA) to search for an optimal solution to a realistically formulated economic dispatch (ED) problem. GA is a global search technique based on principles inspired from the genetic and evolution mechanism observed in natural biological systems. A major drawback of the conventional GA (CGA) approach is that it can be time consuming. The micro-GA (µGA) approach has been proposed as a better time efficient alternative for some engineering problems. The effectiveness of CGA and µGA. to solving ED problem is initially verified on an IEEE 3-generating unit, 6-bus test system. Simulation results obtained on this network using CGA and µGA validate their effectiveness when compared with the published results obtained via the classical and the Hopfield neural network approaches. Finally, both GA approaches have been successfully applied to the coordination of the Nigerian 31-bus system fed by four thermal and three hydro generating units. Herein, use has been made of the loss formula developed for the Nigerian system from several power flow studies. For the Nigerian case study, the µGA. is shown to exhibit superior performance than the CGA from both optimal generation allocations and computational time viewpoints

Quantum gates implementations in the separated ion-traps by fast laser pulses

An approach is proposed to implement the universal quantum gates between the ions confined individually in the separated traps. Instead of the typical adiabatic operations, performed for manipulating the ion-ion coupling, here the switchable couplings between ions are implemented non-adiabatically by using the fast laser pulses. Consequently, the desirable quantum gates between the ions could be implemented by using only a series of laser pulses. The proposal may be conveniently generalized to the quantum computation with the scalable ion-traps.Comment: 10 pages, 3figure

Black Holes and Photons with Entropic Force

We study entropic force effects on black holes and photons. We find that application of an entropic analysis restricts the radial change $\Delta R$ of a black hole of radius $R_{\mathrm{H}}$, due to a test particle of a Schwartzchild radius $R_{h}$ moving towards the black hole by $\Delta x$ near black body surface, to be given by a relation $R_{\mathrm{H}} \Delta R= R_h \Delta x/2$, or {\Delta R}/{\lambdabar_M} = {\Delta x}/{2 \lambdabar_m}. We suggest a new rule regarding entropy changes in different dimensions, \Delta S= 2\pi k D \Delta l /\lambdabar, which unifies Verlinde's conjecture and the black hole entropy formula. We also propose to extend the entropic force idea to massless particles such as a photon. We find that there is an entropic force on a photon of energy $E_\gamma$, with $F=G M m_{\gamma}/R^2$, and therefore the photon has an effective gravitational mass $m_\gamma = E_\gamma/c^2$.Comment: 4 Latex pages, no figure

X-ray accretion signatures in the close CTTS binary V4046 Sgr

We present Chandra HETGS observations of the classical T Tauri star (CTTS) V4046 Sgr. The He-like triplets of O VII, Ne IX, and Si XIII are clearly detected. Similar to the CTTS TW Hya and BP Tau, the forbidden lines of O VII and Ne IX are weak compared to the intercombination line, indicating high plasma densities in the X-ray emitting regions. The Si XIII triplet, however, is within the low-density limit, in agreement with the predictions of the accretion funnel infall model with an additional stellar corona. V4046 Sgr is the first close binary exhibiting these features. Together with previous high-resolution X-ray data on TW Hya and BP Tau, and in contrast to T Tau, now three out of four CTTS show evidence of accretion funnels.Comment: 5 pages, 5 figure

Systemic tuberculosis presenting with acute transient myopia: a case report

<p>Abstract</p> <p>Introduction</p> <p>Transient myopia has been reported to occur in a number of conditions, either ocular in origin or associated with an underlying systemic cause. We present a rare case of this abnormality occurring in the setting of systemic tuberculosis.</p> <p>Case presentation</p> <p>A 29-year-old Indian woman presented with sudden onset blurred distance vision and fever. Examination revealed visual acuity of counting fingers in both eyes improving to 6/9 with pinhole with N5 reading acuity. Anterior segment examination revealed narrow angles on gonioscopy. Posterior segments were normal. Systemic examination revealed a fluctuant mass in her left loin, aspiration of which yielded pus which was culture-positive for <it>Mycobacterium tuberculosis</it>. The Mantoux test elicited a strongly positive reaction. Chest X-ray and magnetic resonance imaging of the brain were unremarkable. Computed tomography scan and magnetic resonance imaging of the spine and abdomen revealed a large psoas abscess communicating with the loin mass. Two vertebrae were involved but not the spinal cord or canal.</p> <p>Conclusion</p> <p>Transient myopia is a rare presenting feature of systemic tuberculosis. A postulated mechanism in this patient is that development of a uveal effusion related to systemic tuberculosis caused anterior rotation of the iris-lens diaphragm, thereby inducing narrowing of the angle and acute myopia.</p

The role of honey in the treatment of type 2 diabetes mellitus: a review of literature

The use of honey in the control of hyperglycemia in patients with type 2 diabetes mellitus is a current option being explored globally. Honey bees which are named in Latin as Apis, use the collected nectar from plants to produce honey after regurgitation and digestion of nectar. Carbohydrate constitutes about 80% of the components of honey. It includes monosaccharides [fructose (37.5%) and glucose (30.6%), disaccharides (sucrose (1.6%) and maltose (2.7%)] and oligosaccharides. Natural honey also contains water (17.2%), proteins, vitamins, minerals, enzymes, acids such as flavonoids, phenolic acids and other components. Honey is rich in antioxidant content and these antioxidant compounds function as endogenous cellular antioxidant defences against free radicals in diabetes mellitus. Antioxidants have also been shown to exert a beneficial effects on blood glucose. Fructose and other bioactive constituents of honey have also been linked with amelioration of hyperglycemia. Besides the beneficial effects of honey on blood glucose, honey is widely used in the management of diabetic foot ulcers, an important complication of diabetes mellitus. The wound-healing benefits of honey are attributed to its antioxidant constituents and broad-spectrum antimicrobial activity. Though additional studies are needed, the use of honey in the management of diabetes mellitus holds much promise

Non-uniform Black Strings with Schwarzschild-(Anti-)de Sitter Foliation

We present some exact non-uniform black string solutions of 5-dimensional pure Einstein gravity as well as Einstein-Maxwell-dilaton theory at arbitrary dilaton coupling. The solutions share the common property that their 4-dimensional slices are Schwarzchild-(anti-)de Sitter spacetimes. The pure gravity solution is also generalized to spacetimes of dimensions higher than 5 to get non-uniform black branes.Comment: LaTeX 14 pages, 3 eps figures. V2: version appeared in CQ

Muon spin rotation measurements of the superfluid density in fresh and aged superconducting PuCoGa5_5

We have measured the temperature dependence and magnitude of the superfluid density $\rho_{\rm s}(T)$ via the magnetic field penetration depth $\lambda(T)$ in PuCoGa$_5$ (nominal critical temperature $T_{c0} = 18.5$ K) using the muon spin rotation technique in order to investigate the symmetry of the order parameter, and to study the effects of aging on the superconducting properties of a radioactive material. The same single crystals were measured after 25 days ($T_c = 18.25$ K) and 400 days ($T_c = 15.0$ K) of aging at room temperature. The temperature dependence of the superfluid density is well described in both materials by a model using d-wave gap symmetry. The magnitude of the muon spin relaxation rate $\sigma$ in the aged sample, $\sigma\propto 1/\lambda^2\propto\rho_s/m^*$, where $m^*$ is the effective mass, is reduced by about 70% compared to fresh sample. This indicates that the scattering from self-irradiation induced defects is not in the limit of the conventional Abrikosov-Gor'kov pair-breaking theory, but rather in the limit of short coherence length (about 2 nm in PuCoGa$_5$) superconductivity.Comment: 11 page