Exact Haldane mapping for all SS and super universality in spin chains

The low energy dynamics of the anti-ferromagnetic Heisenberg spin $S$ chain in the semiclassical limit $S\to\infty$ is known to map onto the O(3) nonlinear $\sigma$ model with a $\theta$ term in 1+1 dimension. Guided by the underlying dual symmetry of the spin chain, as well as the recently established topological significance of "dangling edge spins," we report an {\em exact} mapping onto the O(3) model that avoids the conventional large $S$ approximation altogether. Our new methodology demonstrates all the super universal features of the $\theta$ angle concept that previously arose in the theory of the quantum Hall effect. It explains why Haldane's original ideas remarkably yield the correct answer in spite of the fundamental complications that generally exist in the idea of semiclassical expansions

Development of a scalable generic platform for adaptive optics real time control

The main objective of the present project is to explore the viability of an adaptive optics control system based exclusively on Field Programmable Gate Arrays (FPGAs), making strong use of their parallel processing capability. In an Adaptive Optics (AO) system, the generation of the Deformable Mirror (DM) control voltages from the Wavefront Sensor (WFS) measurements is usually through the multiplication of the wavefront slopes with a predetermined reconstructor matrix. The ability to access several hundred hard multipliers and memories concurrently in an FPGA allows performance far beyond that of a modern CPU or GPU for tasks with a well defined structure such as Adaptive Optics control. The target of the current project is to generate a signal for a real time wavefront correction, from the signals coming from a Wavefront Sensor, wherein the system would be flexible to accommodate all the current Wavefront Sensing techniques and also the different methods which are used for wavefront compensation. The system should also accommodate for different data transmission protocols (like Ethernet, USB, IEEE 1394 etc.) for transmitting data to and from the FPGA device, thus providing a more flexible platform for Adaptive Optics control. Preliminary simulation results for the formulation of the platform, and a design of a fully scalable slope computer is presented.Comment: Paper presented as part of SPIE ICOP 2015 Conference Proceeding

Performance Evaluation of Energy Efficient Protocols in Wireless Sensor Networks

Reducing the energy utilization is an important element in the Wireless Sensor network (WSN). Many protocols have been designed for improving energy efficiency of the network. Clustering protocols have been proved to be one of the energy-efficient protocols in WSN. One of the basic and most popular protocols designed using the clustering approach is the LEACH (Low-Energy Adaptive Clustering Hierarchy).However, LEACH undergoes an issue of bad distribution of cluster heads, which is overcome by implementing a technique of selecting smart cluster head in LEACH known as SCHS (Smart Cluster Head Selection).Also another clustering protocol HEED (Hybrid Energy Efficient Distributed) which follows the principle of LEACH is considered for the study purpose. In this paper, a thorough analysis of three clustering protocols was carried out by keeping the network parameters same so as to conclude which protocol amongst the three utilizes the minimum energy and prolongs the network lifetime

THERMAL ANALYSIS OF AUTOMOTIVE CYLINDER HEAD MADE BY ALUMINIUM METAL MATRIX COMPOSITE REINFORCED WITH NANO ALUMINA

Metal Matrix Nano Composites (MMNC’s) have been developed to meet the demand for lighter materials with significant improvements in mechanical and physical properties like high strength, excellent wear resistance, good thermal conductivity, low thermal expansion coefficient with particulate reinforcements. Aluminium based nano composites (AA356 – nano Al2O3) with three different percentage (1%, 1.5%, 2.5% Wt) of nano – alumina particulate reinforcement (~40 nm) were fabricated using in-situ stir casting technique. Mechanical properties characterization which strongly depends on microstructural properties of reinforcement revealed that the presence of nano – alumina particulates lead to simultaneous increase in hardness, UTS, wear behaviour. The results revealed that UTS, Hardness, Wear behaviour increases with the increase in the percentage of reinforcement of nano – Al2O3 whereas the thermal conductivity drops with increasing percentage of reinforcement when compared to the base alloy AA356. An attempt is made in the present study to review the opportunities of using such a MMNC developed in automotive brake drum replacing the current system using cast iron

Research in the University of Calicut, India

This paper examines the growth of scholarly articles produced by the University of Calicut over a period of fifty one years to identify the growth and trend of research. Data was collected from Scopus database. As of 30th September 2018, a total number of 2158 scholarly articles have been published by the university. The study found that more papers were published on Agricultural and Biological Sciences (30%) followed by Chemistry (23%) and Physics and Astronomy combination (21%). The publications of scholarly articles in Social Sciences, Business, Management and Accounting, Arts and Humanities, Psychology, Economics, Econometrics and Finance were found to be very less (3.7%). The majority of articles (58%) were published during the last ten years (58%)

Dynamic Race Prediction in Linear Time

Writing reliable concurrent software remains a huge challenge for today's programmers. Programmers rarely reason about their code by explicitly considering different possible inter-leavings of its execution. We consider the problem of detecting data races from individual executions in a sound manner. The classical approach to solving this problem has been to use Lamport's happens-before (HB) relation. Until now HB remains the only approach that runs in linear time. Previous efforts in improving over HB such as causally-precedes (CP) and maximal causal models fall short due to the fact that they are not implementable efficiently and hence have to compromise on their race detecting ability by limiting their techniques to bounded sized fragments of the execution. We present a new relation weak-causally-precedes (WCP) that is provably better than CP in terms of being able to detect more races, while still remaining sound. Moreover it admits a linear time algorithm which works on the entire execution without having to fragment it.Comment: 22 pages, 8 figures, 1 algorithm, 1 tabl

First-passage time statistics of stochastic transcription process for time-dependent reaction rates

Transcription in gene expression is an intrinsically noisy process which involves production and degradation of mRNAs. An important quantity to describe this stochastic process is the first-passage time (FPT), i.e., the time taken by mRNAs to reach a particular threshold. The process of transcription can be modelled as a simple birth-death process, assuming that the promoter is always in an active state and to encode the stochastic environment we consider the transcription rate to be time dependent. This generalization is suitable to capture bursty mRNA dynamics usually modelled as an ON-Off model and simplifies the calculation of FPT statistics for a cell population. We study the role of periodic modulation of the transcription rate on different moments of FPT distribution of a population of cells. Our calculation shows that for sinusoidal modulation there exists an extremal value of mean FPT as a function of the time period and phase of the transcription signal. However, for the square wave modulation of transcription rates simulation results show that the extremal value of the MFPT behaves monotonically with the variation of the phase

Spin-1 chain with spin-1/2 excitations in the bulk

We present a spin-1 chain with a Hamiltonian which has three exactly solvable ground states. Two of these are fully dimerized, analogous to the Majumdar-Ghosh (MG) states of a spin-1/2 chain, while the third is of the Affleck-Kennedy-Lieb-Tasaki (AKLT) type. We use variational and numerical methods to study the low-energy excitations which interpolate between these ground states in different ways. In particular, there is a spin-1/2 excitation which interpolates between the MG and AKLT ground states; this is the lowest excitation of the system and it has a surprisingly small gap. We discuss generalizations of our model of spin fractionalization to higher spin chains and higher dimensions.Comment: 7 pages including 4 figures; this is the published version of the pape

Study on Physico- Chemical Parameters and Structural Characterization of Soils in Pudukkottai District of Tamilnadu, India

The soil is the most important constituent to fulfilment of all the basic needs of human beings and also is an important component of our farming. The study was conducted with the main objective to investigate the soil samples of Pudukkottai district of Tamil Nadu for its physico-chemical analysis and structural characterization. The collected soil samples were analyzed for its pH, EC, Nitrogen, Phosphorus, Potassium, Zinc and Iron. Besides, the sample was characterized by FTIR studies for structural conformation. From the study the results revealed that the collected soil was red soil and its texture was sandy clay loam. The soil pH was 9.29 which was alkaline and the EC was 0.02 dSm-1. The available macro-nutrients as nitrogen, phosphorus and potassium for paddy field soil samples had 118, 11 and 160 kg/ha respectively. Micronutrients Nutrients also analyzed. FT-IR spectrum of soil was recorded spectrum of soil was shown the C-H deformation vibrations occur at 1402. The C=C Stretching vibrations occur at 1644 and the N-H Stretching vibrations occur at 2344. Management options to improve the soil fertility were discussed