On the Landau-Ginzburg description of Boundary CFTs and special Lagrangian submanifolds

We consider Landau-Ginzburg (LG) models with boundary conditions preserving A-type N=2 supersymmetry. We show the equivalence of a linear class of boundary conditions in the LG model to a particular class of boundary states in the corresponding CFT by an explicit computation of the open-string Witten index in the LG model. We extend the linear class of boundary conditions to general non-linear boundary conditions and determine their consistency with A-type N=2 supersymmetry. This enables us to provide a microscopic description of special Lagrangian submanifolds in C^n due to Harvey and Lawson. We generalise this construction to the case of hypersurfaces in P^n. We find that the boundary conditions must necessarily have vanishing Poisson bracket with the combination (W(\phi)-\bar{W}(\bar{\phi})), where W(\phi) is the appropriate superpotential for the hypersurface. An interesting application considered is the T^3 supersymmetric cycle of the quintic in the large complex structure limit.Comment: 28+1 pages; no figures; requires JHEP.cls, amssymb; (v2) typo corrected; (v3) references adde

Probabilistic Monte-Carlo method for modelling and prediction of electronics component life

Power electronics are widely used in electric vehicles, railway locomotive and new generation aircrafts. Reliability of these components directly affect the reliability and performance of these vehicular platforms. In recent years, several research work about reliability, failure mode and aging analysis have been extensively carried out. There is a need for an efficient algorithm able to predict the life of power electronics component. In this paper, a probabilistic Monte-Carlo framework is developed and applied to predict remaining useful life of a component. Probability distributions are used to model the component’s degradation process. The modelling parameters are learned using Maximum Likelihood Estimation. The prognostic is carried out by the mean of simulation in this paper. Monte-Carlo simulation is used to propagate multiple possible degradation paths based on the current health state of the component. The remaining useful life and confident bounds are calculated by estimating mean, median and percentile descriptive statistics of the simulated degradation paths. Results from different probabilistic models are compared and their prognostic performances are evaluated

Improved Method of Generating Bit Reserved Numbers for Calculating Fast Fourier Transform

Fast Fourier Transform (FFT) is an important tool required for signal processing in defence applications. This paper reports an improved method for generating bit reversed numbers needed in calculating FFT using radix-2. The refined algorithm takes advantage of some features of the bit reversed numbers, using intermediate array for storage and improved procedure for calculating base values required when generating bit reversed numbers

A Study on Brain Abscess

INTRODUCTION: Brain abscess is defined as a focal, intra cerebral infection that begins as a localized area of cerebritis and develops into a collection of pus surrounded by a well-vascularized capsule. Although rare in developed countries brain abscess still remains a significant health care problem in developing countries. Historically brain abscess was mentioned by Hippocrates in 460 BC and he himself has described the association of brain abscess with ear infection. The Brain is well protected from infections by a thick skull vault, tough duramater and important barriers like bloodbrain barrier and blood cerebrospinal fluid (CSF) barrier. A breach in any of these barriers leads to entry of microorganisms into the brain initiating a suppurative inflammation culminating in brain abscess. The inciting organism can be introduced from outside by trauma or endogenously from infection in a contiguous site eg. ear or occasionally blood borne, heart disease and systemic infection. Although the portal of entry of the organism is commonly identified, the organism remains obscure in 10 -37% of the patients. In the recent decades the addition of Computed tomography (CT) and Magnetic Resonance Imaging (MRI) to the diagnostic armamentarium has facilitated early identification and thereby prompt institution of therapy in brain abscess. Improved microbiological techniques have increased the appreciation of the bacteriological spectrum of brain abscess especially anaerobes. The advanced surgical techniques viz. stereotactic guided aspiration, real-time ultrasound imaging has caused a paradigm shift in the management and outcome of brain abscess. AIM OF THE STUDY: The aim is to study the epidemiology, clinical profile, management and outcome in patients with brain abscess. MATERIALS AND METHODS: All patients admitted in the Institute of Neurology, Rajiv Gandhi Government General Hospital & Madras Medical College, Chennai, between August 2010 and February 2013, with brain abscess was included in this study. Inclusion Criteria: All patients who have been diagnosed as having brain abscess were included in the study group. On admission patient’s clinical profile such as age, sex, presenting symptoms complete neurological examination, conscious level and signs were recorded. All patients were subjected to CT scan brain plain study. In CT of patients having brain abscess the following features were noted – location, number of abscess, loculation, associated hydrocephalus. Patients were either managed conservatively or by surgery. The specimen obtained by surgical means was subjected to microbiological study. All the data were entered in a proforma as shown in the appendix. Outcome analysis was done at the time of discharge. CONCLUSION: A study of 60 patients presenting with brain abscess has lead to the following conclusions. 1. Brain abscess still occurs in the modern era, better visualized with modern imaging studies. 2. Retro viral infections also contribute for brain abscess apart from other known causes, hence all cases of brain abscesses to be screened for retro viral infection. 3. Neonates and children show poor prognosis and prompt aggressive management is essential for better outcome. 4. Constant vigil and surveillance will help for decreasing the magnitude of morbidity and mortality from brain abscess

Strong Secrecy for Erasure Wiretap Channels

We show that duals of certain low-density parity-check (LDPC) codes, when used in a standard coset coding scheme, provide strong secrecy over the binary erasure wiretap channel (BEWC). This result hinges on a stopping set analysis of ensembles of LDPC codes with block length $n$ and girth $\geq 2k$, for some $k \geq 2$. We show that if the minimum left degree of the ensemble is $l_\mathrm{min}$, the expected probability of block error is \calO(\frac{1}{n^{\lceil l_\mathrm{min} k /2 \rceil - k}}) when the erasure probability $\epsilon < \epsilon_\mathrm{ef}$, where $\epsilon_\mathrm{ef}$ depends on the degree distribution of the ensemble. As long as $l_\mathrm{min} > 2$ and $k > 2$, the dual of this LDPC code provides strong secrecy over a BEWC of erasure probability greater than $1 - \epsilon_\mathrm{ef}$.Comment: Submitted to the Information Theory Workship (ITW) 2010, Dubli

Effect of Cu/Zn on Material Removal Rate on Grey Cast Iron

Electrical Discharge machining (EDM) is capable of machining geometrically complex or hard material component and a widely used process in manufacturing industries for a high-precision machining of all types of conductive materials. Material of any hardness can be machined because the hardness is not a foremost parameter in EDM. In this paper, the effect of EDM parameters such as Pulse on Time, Pulse off Time, voltage and current on material removal rate (MRR) in Cast iron is investigated. Cast iron is an important material used in various applications because of its high hardness. Brass, whose main constituents are copper and zinc, is used as a tool material and the influence of copper and Zinc on cast iron workpiece is studied. Experiment is carried out and the results were analyzed using analysis of Variance and response graphs. Signal to Noise is used to identify the contribution of each cutting parameter towards the material removal rate.Â

Value Appropriation in Business Process Outsourcing

We examine the relative value gains between client and vendor firms following the announcement of a BPO deal. We posit that the gains for the vendor are higher than those of the client when clients outsource primary tasks with intent to access vendor capabilities and when the clients outsource peripheral tasks with intent to minimize costs. We also posit that the gains for the clients are higher than those of the vendor when the clients outsource primary tasks with intent to minimize costs and when the clients outsource peripheral tasks to access vendor capabilities. Using an event study methodology we examine 221 BPO contracts between the years 2000 and 2013 to test our hypotheses. In general we found that, when clients outsourced with intent as cost reduction, the vendors gained relative to the client for both primary and peripheral tasks. We interpret and discuss these findings and research implications