Optimal Power Allocation for Channel Estimation in MIMO-OFDM System with Per-Subcarrier Transmit Antenna Selection

A novel hybrid channel estimator is proposed for multiple-input multiple-output orthogonal frequency- division multiplexing (MIMO-OFDM) system with per-subcarrier transmit antenna selection having optimal power allocation among subcarriers. In practice, antenna selection information is transmitted through a binary symmetric control channel with a crossover probability. Linear minimum mean-square error (LMMSE) technique is optimal technique for channel estimation in MIMO-OFDM system. Though LMMSE estimator performs well at low signal to noise ratio (SNR), in the presence of antenna-to-subcarrier-assignment error (ATSA), it introduces irreducible error at high SNR. We have proved that relaxed MMSE (RMMSE) estimator overcomes the performance degradation at high SNR. The proposed hybrid estimator combines the benefits of LMMSE at low SNR and RMMSE estimator at high SNR. The vector mean square error (MSE) expression is modified as scalar expression so that an optimal power allocation can be performed. The convex optimization problem is formulated and solved to allocate optimal power to subcarriers minimizing the MSE, subject to transmit sum power constraint. Further, an analytical expression for SNR threshold at which the hybrid estimator is to be switched from LMMSE to RMMSE is derived. The simulation results show that the proposed hybrid estimator gives robust performance, irrespective of ATSA error

Перспективы использования магнезиальных пород

A new operation mode of the lens system in electron energy loss spectrometers is proposed which brings the cardinal plane of the lenses closer to the sample. Experiments as well as electron optical calculations show an intensity gain by a factor of 3-4. The required voltages on the lens elements are calculated as function of the impact energy at the sample. Furthermore, the lens system is characterized with respect to the solid angle probed by the spectrometer and the transmission which enables the evaluation of spectral intensities in terms of the absolute scattering probability for elastic and inelastic scattering. The results apply to most existing electron energy loss spectrometers as they stem from the same design and use identical lens systems. (C) 2012 Elsevier B.V. All rights reserved

ENZYME PRODUCTION ABILITY BY BACILLUS SUBTILIS AND BACILLUS LICHENIFORMIS - A COMPARATIVE STUDY

Objective: B.subtilis and B.licheniformis have been reported as one of the potential protease producer. Hence, an attempt has been made to optimize and compare the enzyme production by entrapment and fermentor conditions. Methods: Growth profile of both the strains has been studied. Optimization of culture conditions with respect to pH, temperature, agitation, carbon, nitrogen sources and metals has also been analyzed. Immobilization studies have been conducted for the strains. Enzyme production ability in fermentor has been premeditated. Results: Growth profile for both the strains was found to be similar. Strains were optimized for maximal enzyme production. Fermentation has yielded higher production of enzyme (8080 U/ml) compared to immobilization (850 U/ml). Conclusion: B.subtilis was more stable in enzyme production with immobilization and fermentation when compared to B.licheniformis.Keywords: B.subtilis, B.licheniformis, Immobilization, Fermentatio

A Study on Bacterial Infections and their Antimicrobial Susceptibility Pattern in Decompensated Liver Disease Patients in a Tertiary Care Hospital

INTRODUCTION: Bacterial infections in decompensated liver disease (DCLD) patients are one of the most frequent complications and result in high mortality and morbidity. Patients with DCLD have altered and impaired immunity, which favours bacterial infections. The most common infection in DCLD patients are spontaneous bacterial peritonitis followed by urinary tract infections, Spontaneous bacteraemia, pneumonia, and skin and soft-tissue infections. The prognosis of these patients is closely related to a prompt and accurate diagnosis and appropriate treatment decreases the mortality rates. AIM AND OBJECTIVE: This study was done to determine the various bacterial agents causing infections in decompensated liver disease patients and to determine the drug susceptibility and resistance pattern and to identify their associated risk factors (HBV, HCV) and to estimate the level of C3 component of complement in DCLD patients by ELISA. This study was conducted at the Institute of Microbiology, Madras Medical College, Chennai MATERIALS AND METHODS: About 150 patients (≥18 yrs), admitted in various wards of our hospital with signs & symptoms suggestive of bacterial infections in DCLD patients are included in the study. Ascitic fluid, urine, sputum and wound swab were collected. Blood and serum samples were collected from all the patients and processed according to Standard Microbiological techniques. Detection of HBsAg, Anti HCV ELISA was done according to the manufacturer guidelines to find out the associated risk factors for DCLD and to correlate the bacterial infections with complement C3 level by ELISA. Results: A total of 150 DCLD patients, from September 2013 to August 2014, were included. The common age group involved was 41-60 years, being 97% male. The alcoholic etiology of DCLD was 84%. Out of 150 samples, culture positivity seen in 54% (81/150).In 81 culture positive isolates, 63 (78%) were Gram Negative bacilli and 18 (22%) were Gram Positive cocci, which was correlated significantly [P value = 0.005]. Among 81 culture positive cases, The most common infection in DCLD patients are spontaneous bacterial peritonitis[27%] followed by urinary tract infections[26%], Spontaneous bacteraemia[19%], pneumonia[16%], and skin and soft-tissue infections[12%]. Among Gram negative bacilli, Escherichia coli were the most common isolates and in Gram positive cocci, Staphylococcus aureus was the most common isolates. Most of the organisms were 75% sensitive to amino glycosides and 50% sensitive to fluoroquinolones. All the GNB were 100% sensitive to carbapenem except one carbapenem resistant isolates, Klebsiella oxytoca was isolated from sputum sample. In 81 culture-positive infections, 33[41%] drug resistant bacterial infections were identified: 27 ESBL (81%), 4 Methicillin resistant Staphylococcus aureus (10%) 1 VRE (2.3%), and 1 MBL(2.3%). Of the culture-positive infections, these drug resistant bacterial infections occurred in 11 of 21 (52%) of the UTIs, 8 of 22 (36%) of the SBP, 3 of 15 (20%) of the spontaneous bacteraemia cases, 7 of 13 (54%) of the pneumonia and 4 of 10 (40%) of the skin and soft tissue infection cases. In our study, the prevalence of Hepatitis B surface antigen and Anti hepatitis C virus by serological methods (ELISA) were found to be 8% and 7.3% respectively. Out of 150 total samples, Complement component C3 ELISA was done for randomly selected 88 samples with one kit due to economic constrains. Out of 88 patients, 59 (67%) patients with low complement component C3 level. Of which 35 (59%) patients were culture positive and 24 (41%) were culture negative. 29 (33%) with normal complement component C3 level, of which 25 (86%) were culture negative and 4 (14%) were culture positive. DISCUSSION: In our study, males were commonly involved in DCLD patients due to presence of risk factors like alcoholism. The main causes of DCLD were alcoholic liver diseases. The commonest age group which showed most of the bacterial infections was between 41-50 age groups. The most common and serious bacterial infections in DCLD patients were Spontaneous bacterial peritonitis than other infections. Gram negative bacilli were common isolates than Gram positive cocci. In Gram negative bacilli, E.coli was the main pathogen. High rate of antibiotic resistant isolates were seen in culture-positive infections, with 41% (33 of 81cases). Bacterial infections were associated with low complement component C3 level in DCLD patients. CONCLUSION: The prognosis of these patients is closely related to identify the definitive etiologic diagnosis with its antimicrobial susceptibility and resistant pattern. Antibiotic prophylaxis must be restricted to selected patients and encouraging the use of first line antibiotics and to avoid unnecessary use of higher antibiotics like third generation cephalosporins will help to reduces the occurrence of new resistant strains, which can be significantly reduce hospital stay and morbidity and improve survival rate

1-Benzyl-3,5-bis­[(E)-3-thienyl­methyl­idene]piperidin-4-one

In the title mol­ecule, C22H19NOS2, the piperidine ring adopts an envelope conformation with the benzyl substituent in an equatorial position. Each of the olefinic double bonds has an E configuration. The dihedral angle between the two thio­phene rings is 1.55 (18)°. The thio­phene rings form angles of 72.21 (14) and 73.43 (14)° with the phenyl ring. Both thio­phene rings are disordered over two orientations [occupancy ratios of 0.799 (1):0.201 (1)] at 180° from one another. In the crystal, weak inter­molecular C—H⋯O hydrogen bonds and C—H⋯π inter­actions help to stabilize the packing

CONSUMER BEHAVIOUR: AN EMPIRICAL STUDY ON CONSUMERS' PERCEPTION ON PURCHASE BEHAVIOUR TOWARDS E-PRODUCTS THROUGH E-RETAIL MARKET

Abstract The emergence of internet has created opportunities for firms to stay competitive by providing customers with a convenient, faster and cheaper way to make purchases. Electronic Retailing is more than just buying and selling products online. It also includes entire online process of developing, marketing, selling, delivering, servicing and paying for products and services. India has shown tremendous growth in E-Retailing segment. With an internet user base of over 300 million, India has third largest internet population after US & China. India has witnessed major breakthrough E-commerce success stories particularly in e-retail in Consumer Electronics & Fashion Apparel & Home Furnishing segments. E-Retailing creates new opportunities for entrepreneurial start-ups. Ease of Internet access, Safe and secure payment modes coupled with aggressive marketing by E-Retailing Giants has revolutionized this segment. Rapid development in mobile technology has given way to e-logistics companies to serve people as and when required very effectively

Laser-Induced Skyrmion Writing and Erasing in an Ultrafast Cryo-Lorentz Transmission Electron Microscopy

We demonstrate that light-induced heat pulses of different duration and energy can write skyrmions in a broad range of temperatures and magnetic field in FeGe. Using a combination of camera-rate and pump-probe cryo-Lorentz Transmission Electron Microscopy, we directly resolve the spatio-temporal evolution of the magnetization ensuing optical excitation. The skyrmion lattice was found to maintain its structural properties during the laser-induced demagnetization, and its recovery to the initial state happened in the sub-{\mu}s to {\mu}s range, depending on the cooling rate of the system