Bulk Viscosity of Magnetized Neutron Star Matter

We study the effect of magnetic field on the bulk viscosity of nuclear matter in neutron stars. We employ the framework of relativistic mean field theory to observe the dense nuclear matter in neutron stars. The effects are first studied for the case when the magnetic field does not exceed the critical value to confine the electrons to the lowest Landau levels. We then consider the case of intense magnetic field to evaluate viscosity for the URCA processes and show that the inequality $p_{F}(e)+p_{F}(p)\geq p_{F}(n)$ is no longer required to be satisfied for the URCA processes to proceed.Comment: Latex 2e file with four postscripts figure

Contagion Risk and Network Design

Individuals derive bene ts from their connections, but these may, at the same time, transmit external threats. Individuals therefore invest in security to protect themselves. However, the incentives to invest in security depend on their network exposures. We study the problem of designing a network that provides the right individual incentives. Motivated by cybersecurity, we rst study the situation where the threat to the network comes from an intelligent adversary. We show that, by choosing the right topology, the designer can bound the welfare costs of decentralized protection. Both over-investment as well as under-investment can occur depending on the costs of security. At low costs, over-protection is important: this is addressed by discon- necting the network into two unequal components and sacri cing some nodes. At high costs, under-protection becomes salient: it is addressed by disconnecting the network into equal components. Motivated by epidemiology, we then turn to the study of random attacks. The over-protection problem is no longer present, whereas under-protection problems is mitigated in a diametrically opposite way: namely, by creating dense networks that expose the individuals to the risk of contagion

Comparison of the Effects of Zonisamide, Ethosuximide and Pregabalin in the Chronic Constriction Injury Induced Neuropathic Pain in Rats

Background: Evidence has been generated that various anticonvulsant agents provide relief of several chronic pain syndromes and therefore as an alternative to opioids, nonsteroidal anti.inflammatory, and tricyclic antidepressant drugs in the treatment of neuropathic pain. The results of these studies thus raise the question of whether all anticonvulsant drugs or particular mechanistic classes may be efficacious in the treatment of neuropathic pain syndromes.Aim: The aim was to compare the clinically used anticonvulsant drugs which are differ in their mechanism of action in a chronic pain model, the chronic constriction injury, in order to determine if all anticonvulsants or only particular mechanistic classes of anticonvulsants are analgesic.Materials and Methods: The study included zonisamide, ethosuximide and pregabalin. All compounds were anticonvulsant with diverse mechanism of actions. The peripheral neuropathic pain was induced by chronic constriction injury of the sciatic nerve in male Sprague.Dawley rats. Zonisamide (80 and 40 mg/kg), ethosuximide (300 and 100 mg/kg), pregabalin (50 and 20 mg/kg), and saline was administered intraperitoneally in respective groups in a blinded, randomized manner from postoperative day (POD) 7.13. Paw withdrawal duration to spontaneous pain, chemical allodynia and  mechanical hyperalgesia and paw withdrawal latency to mechanical  allodynia and thermal hyperalgesia were tested before drug administration on POD7 and after administration on POD 7, 9, 11 and 13.Results: The present study suggests that these drugs could provide an effective alternative in the treatment of neuropathic pain. However, zonisamide and pregabalin appears to have suitable efficacy to treat a wide spectrum of neuropathic pain condition. Conclusion: The present findings suggest that the inhibition of N.type calcium channels or voltage.gated sodium and T.type calcium channels provides better analgesic potential instead of inhibition of T.type calcium channels alone.Keywords: Chronic constriction injury model, Ethosuximide, Neuropathic pain, Pregabalin, Zonisamid

Information processing and signal integration in bacterial quorum sensing

Bacteria communicate using secreted chemical signaling molecules called autoinducers in a process known as quorum sensing. The quorum-sensing network of the marine bacterium {\it Vibrio harveyi} employs three autoinducers, each known to encode distinct ecological information. Yet how cells integrate and interpret the information contained within the three autoinducer signals remains a mystery. Here, we develop a new framework for analyzing signal integration based on Information Theory and use it to analyze quorum sensing in {\it V. harveyi}. We quantify how much the cells can learn about individual autoinducers and explain the experimentally observed input-output relation of the {\it V. harveyi} quorum-sensing circuit. Our results suggest that the need to limit interference between input signals places strong constraints on the architecture of bacterial signal-integration networks, and that bacteria likely have evolved active strategies for minimizing this interference. Here we analyze two such strategies: manipulation of autoinducer production and feedback on receptor number ratios.Comment: Supporting information is in appendi

An Information-Geometric Reconstruction of Quantum Theory, I: The Abstract Quantum Formalism

In this paper and a companion paper, we show how the framework of information geometry, a geometry of discrete probability distributions, can form the basis of a derivation of the quantum formalism. The derivation rests upon a few elementary features of quantum phenomena, such as the statistical nature of measurements, complementarity, and global gauge invariance. It is shown that these features can be traced to experimental observations characteristic of quantum phenomena and to general theoretical principles, and thus can reasonably be taken as a starting point of the derivation. When appropriately formulated within an information geometric framework, these features lead to (i) the abstract quantum formalism for finite-dimensional quantum systems, (ii) the result of Wigner's theorem, and (iii) the fundamental correspondence rules of quantum theory, such as the canonical commutation relationships. The formalism also comes naturally equipped with a metric (and associated measure) over the space of pure states which is unitarily- and anti-unitarily invariant. The derivation suggests that the information geometric framework is directly or indirectly responsible for many of the central structural features of the quantum formalism, such as the importance of square-roots of probability and the occurrence of sinusoidal functions of phases in a pure quantum state. Global gauge invariance is seen to play a crucial role in the emergence of the formalism in its complex form.Comment: 26 page

Electrical properties of a-antimony selenide

This paper reports conduction mechanism in a-\sbse over a wide range of temperature (238K to 338K) and frequency (5Hz to 100kHz). The d.c. conductivity measured as a function of temperature shows semiconducting behaviour with activation energy $\Delta$E= 0.42 eV. Thermally induced changes in the electrical and dielectric properties of a-\sbse have been examined. The a.c. conductivity in the material has been explained using modified CBH model. The band conduction and single polaron hopping is dominant above room temperature. However, in the lower temperature range the bipolaron hopping dominates.Comment: 9 pages (RevTeX, LaTeX2e), 9 psfigures, also at http://pu.chd.nic.in/ftp/pub/san16 e-mail: gautam%[email protected]