Dynamics of Fundamental Matter in N=2* Yang-Mills Theory

We study the dynamics of quenched fundamental matter in $\mathcal{N}=2^\ast$ supersymmetric large $N$ SU(N) Yang-Mills theory at zero temperature. Our tools for this study are probe D7-branes in the holographically dual $\mathcal{N}=2^\ast$ Pilch-Warner gravitational background. Previous work using D3-brane probes of this geometry has shown that it captures the physics of a special slice of the Coulomb branch moduli space of the gauge theory, where the $N$ constituent D3-branes form a dense one dimensional locus known as the enhancon, located deep in the infrared. Our present work shows how this physics is supplemented by the physics of dynamical flavours, revealed by the D7-branes embeddings we find. The Pilch-Warner background introduces new divergences into the D7-branes free energy, which we are able to remove with a single counterterm. We find a family of D7-brane embeddings in the geometry and discuss their properties. We study the physics of the quark condensate, constituent quark mass, and part of the meson spectrum. Notably, there is a special zero mass embedding that ends on the enhancon, which shows that while the geometry acts repulsively on the D7-branes, it does not do so in a way that produces spontaneous chiral symmetry breaking.Comment: 24 pages, 8 figures. Corrected typos, added comment about counterterm. To appear in JHE

Quantum thermodynamics at critical points during melting and solidification processes

We systematically explore and show the existence of finite-temperature continuous quantum phase transition (CTQPT) at a critical point, namely, during solidification or melting such that the first-order thermal phase transition is a special case within CTQPT. Infact, CTQPT is related to chemical reaction where quantum fluctuation (due to wavefunction transformation) is caused by thermal energy and it can occur maximally for temperatures much higher than zero Kelvin. To extract the quantity related to CTQPT, we use the ionization energy theory and the energy-level spacing renormalization group method to derive the energy-level spacing entropy, renormalized Bose-Einstein distribution and the time-dependent specific heat capacity. This work unambiguously shows that the quantum phase transition applies for any finite temperatures.Comment: To be published in Indian Journal of Physics (Kolkata

Effect of leaf extracts of Draceana aborea l. and Vitex doniana sweet on the larvae of Anopheles mosquito

The leaf extracts of Draceana aborea and Vitex doniana of Agavaceae and Verbenaceae families respectively, were tested on the larvae of anopheles mosquito for their botanical insecticidal effects. The results of the investigation showed that the minimum percentage mortality concentration (MPMC) of these leaf extracts on the test organisms were at 75ml/20ml and 10ml/20ml as the startng ponts for D. aborea and V. doniana, respectively. Findings equally revealed that the combination of D. aborea and V. doniana leaf extracts exerted synergistic effects on these organisms at 5.0ml/20ml, whereas the use of the D. aborea and V. doniana extracts separately resulted in reduced efficacy. Analysis of variance showed that, there was no significandifference (P = 0.01) between the synergy and the individual treatments of the leaf extracts on these organisms. Preliminary phytochemical screening showed the presence of flavonoids, free phenolics, condensed tannins, pseudoanins, triterpenes, glycosides and saponins which have someinsecticidal effects on their targeted organisms. These findings represent one of the steps in identifying plants, with insecticidal properties from the rich Bioresources in the Mosaic of the Low-Land Rainforest vegetation zone of Southeastern Nigeria.Keywords: Draceana aborea, Vitex doniana, Leaf extract, Botanical insecticide, Phytochemical, Anopheles mosquito

Enhancement of the immunoregulatory potency of mesenchymal stromal cells by treatment with immunosuppressive drugs

Background aims Multipotent mesenchymal stromal cells (MSCs) are distinguished by their ability to differentiate into a number of stromal derivatives of interest for regenerative medicine, but they also have immunoregulatory properties that are being tested in a number of clinical settings. Methods We show that brief incubations with rapamycin, everolimus, FK506 or cyclosporine A increase the immunosuppressive potency of MSCs and other cell types. Results The treated MSCs are up to 5-fold more potent at inhibiting the induced proliferation of T lymphocytes in vitro. We show that this effect probably is due to adsorption of the drug by the MSCs during pre-treatment, with subsequent diffusion into co-cultures at concentrations sufficient to inhibit T-cell proliferation. MSCs contain measurable amounts of rapamycin after a 15-min exposure, and the potentiating effect is blocked by a neutralizing antibody to the drug. With the use of a pre-clinical model of acute graft-versus-host disease, we demonstrate that a low dose of rapamycin-treated but not untreated umbilical cord–derived MSCs significantly inhibit the onset of disease. Conclusions The use of treated MSCs may achieve clinical end points not reached with untreated MSCs and allow for infusion of fewer cells to reduce costs and minimize potential side effects

Ising model for distribution networks

An elementary Ising spin model is proposed for demonstrating cascading failures (break-downs, blackouts, collapses, avalanches, ...) that can occur in realistic networks for distribution and delivery by suppliers to consumers. A ferromagnetic Hamiltonian with quenched random fields results from policies that maximize the gap between demand and delivery. Such policies can arise in a competitive market where firms artificially create new demand, or in a solidary environment where too high a demand cannot reasonably be met. Network failure in the context of a policy of solidarity is possible when an initially active state becomes metastable and decays to a stable inactive state. We explore the characteristics of the demand and delivery, as well as the topological properties, which make the distribution network susceptible of failure. An effective temperature is defined, which governs the strength of the activity fluctuations which can induce a collapse. Numerical results, obtained by Monte Carlo simulations of the model on (mainly) scale-free networks, are supplemented with analytic mean-field approximations to the geometrical random field fluctuations and the thermal spin fluctuations. The role of hubs versus poorly connected nodes in initiating the breakdown of network activity is illustrated and related to model parameters

Flavor-symmetry Breaking with Charged Probes

We discuss the recombination of brane/anti-brane pairs carrying $D3$ brane charge in $AdS_5 \times S^5$. These configurations are dual to co-dimension one defects in the ${\cal N}=4$ super-Yang-Mills description. Due to their $D3$ charge, these defects are actually domain walls in the dual gauge theory, interpolating between vacua of different gauge symmetry. A pair of unjoined defects each carry localized $(2+1)$ dimensional fermions and possess a global $U(N)\times U(N)$ flavor symmetry while the recombined brane/anti-brane pairs exhibit only a diagonal U(N). We study the thermodynamics of this flavor-symmetry breaking under the influence of external magnetic field.Comment: 21 pages, 10 figure

Influence of membrane-cortex linkers on the extrusion of membrane tubes

The cell membrane is an inhomogeneous system composed of phospholipids, sterols, carbohydrates, and proteins that can be directly attached to underlying cytoskeleton. The protein linkers between the membrane and the cytoskeleton are believed to have a profound effect on the mechanical properties of the cell membrane and its ability to reshape. Here, we investigate the role of membrane-cortex linkers on the extrusion of membrane tubes using computer simulations and experiments. In simulations, we find that the force for tube extrusion has a nonlinear dependence on the density of membrane-cortex attachments: at a range of low and intermediate linker densities, the force is not significantly influenced by the presence of the membrane-cortex attachments and resembles that of the bare membrane. For large concentrations of linkers, however, the force substantially increases compared with the bare membrane. In both cases, the linkers provided membrane tubes with increased stability against coalescence. We then pulled tubes from HEK cells using optical tweezers for varying expression levels of the membrane-cortex attachment protein Ezrin. In line with simulations, we observed that overexpression of Ezrin led to an increased extrusion force, while Ezrin depletion had a negligible effect on the force. Our results shed light on the importance of local protein rearrangements for membrane reshaping at nanoscopic scales

STUDENTS’ KNOWLEDGE AND RISK OF COMMITTING MEDICATION ERRORS IN TWO SCHOOLS OF PHARMACY IN NIGERIA

Objective: The aim of this study was to determine the knowledge of prescription errors, the certainty of such knowledge, and the risk of committing medication errors among pharmacy students in two universities in Nigeria. Methods: This study was a cross-sectional comparative survey between pharmacy students of two universities in Nigeria: University of Nigeria, Nsukka (UNN) and Nnamdi Azikiwe University (NAU), Awka. Study variables were measured using four simulated prescriptions and questionnaires. Chi-square test, independent t-test, and ordinal regression analyses were used to assess study outcomes. Results: A total of 339 pharmacy students (239 in UNN and 100 in NAU), with a mean age of 24 (2.8) years and 57.2% (n=194) male students, participated in this study. Their accurate knowledge of each of the prescriptions were 294 (86.72%), 166 (48.97%), 199 (58.70%), and 248 (73.16%) for prescriptions with error of drug allergy, error of drug interaction, no error, and wrong dose of a drug, respectively. Students from UNN were more likely to commit a statistically significant high risk of error compared to NAU students in prescriptions with a drug allergy and wrong dose, while students in the 4th year class had a statistically significant higher odds of committing a drug interaction prescription error compared to final year students. Conclusion: Pharmacy students evaluated in this study had good knowledge of medication error detection. The risk of these pharmacy students committing a prescription error was evident in nearly all prescriptions tested and the students’ school was the major predictor of these risks