Thinned Concentric Circular Antenna Array Synthesis using Particle Swarm Optimization

AbstractThis paper presents an optimal thinning of a large multiple concentric circular ring arrays of uniformly excited isotropic antennas based on Particle Swarm Optimization method. Circular Antenna Array (CAA) has gained immense popularity in the field of communications nowadays. It has proved to be a better alternative over other types of antenna array configuration due to its all-azimuth scan capability, and the beam pattern which can be kept invariant. In this paper, a 9 ringed Concentric Circular Antenna Array (CCAA) with central element feeding is considered. Extensive simulation results justify the optimization efficacy of the proposed approach for antenna array synthesis. The simulation results show that the number of effective antenna elements can be brought down from 279 to 139 with simultaneous reduction in Side Lobe Level by 20.37dB relative to the main beam with a fixed half power beamwidth using PSO. Real coded Genetic Algorithm (RGA) as well is also adopted to compare the results of PSO algorithm

Nanoindentation studies on waveguides inscribed in chalcogenide glasses using ultrafast laser

Optical straight waveguides are inscribed in GeGaS and GeGaSSb glasses using a high repetition-rate sub-picosecond laser. The mechanical properties of the glasses in the inscribed regions, which have undergone photo induced changes, have been evaluated by using the nanoindentation technique. Results show that the hardness and elastic modulus of the photo-modified glasses are significantly lower as compared to the other locations in the waveguide, which tend to be similar to those of the unexposed areas. The observed mechanical effects are found to correlate well with the optical properties of the waveguides. Further, based on the results, the minimum threshold values of hardness and elastic modulus for the particular propagation mode of the waveguide (single or multi), has been established

Surface Chemical and Settling Studies on Hematite, Quartz and Kaolinite in Presence of Organic Reagents

The industrial practice of beneficiation of iron ores produces substantial amount of slimes which causes loss of iron values and environmental pollution. Slimes consists of extremely fine grained iron bearing minerals, impurities and poses problem in processing by conventional beneficiation techniques. The present study aims to develop flocculation technique for selective separation of iron bearing mineral from slimes. Initial experiments were directed towards understanding surface chemical properties of constituent minerals viz. hematite, quartz and kaolinite with or without organic reagents such as tannic acid, starch and polyacrylamide-co-acrylic acid (m.w.-150 lakh). In this paper, the results of flocculation-dispersion experiments on individual samples of hematite, quartz and kaolinite are discussed as a function of different process parameters such as pH, flocculation time and dosages of reagents. Based on the studies, conditions were established for selective separation of hematite from quartz and kaolinite. The results of flocculation-dispersion of individual minerals were applied to ternary synthetic mineral system

Evanescent-wave coupled right angled buried waveguide: Applications in carbon nanotube mode-locking

In this paper we present a simple but powerful subgraph sampling primitive that is applicable in a variety of computational models including dynamic graph streams (where the input graph is defined by a sequence of edge/hyperedge insertions and deletions) and distributed systems such as MapReduce. In the case of dynamic graph streams, we use this primitive to prove the following results: -- Matching: First, there exists an $\tilde{O}(k^2)$ space algorithm that returns an exact maximum matching on the assumption the cardinality is at most $k$. The best previous algorithm used $\tilde{O}(kn)$ space where $n$ is the number of vertices in the graph and we prove our result is optimal up to logarithmic factors. Our algorithm has $\tilde{O}(1)$ update time. Second, there exists an $\tilde{O}(n^2/\alpha^3)$ space algorithm that returns an $\alpha$-approximation for matchings of arbitrary size. (Assadi et al. (2015) showed that this was optimal and independently and concurrently established the same upper bound.) We generalize both results for weighted matching. Third, there exists an $\tilde{O}(n^{4/5})$ space algorithm that returns a constant approximation in graphs with bounded arboricity. -- Vertex Cover and Hitting Set: There exists an $\tilde{O}(k^d)$ space algorithm that solves the minimum hitting set problem where $d$ is the cardinality of the input sets and $k$ is an upper bound on the size of the minimum hitting set. We prove this is optimal up to logarithmic factors. Our algorithm has $\tilde{O}(1)$ update time. The case $d=2$ corresponds to minimum vertex cover. Finally, we consider a larger family of parameterized problems (including $b$-matching, disjoint paths, vertex coloring among others) for which our subgraph sampling primitive yields fast, small-space dynamic graph stream algorithms. We then show lower bounds for natural problems outside this family

CLINICO-PATHOLOGICAL CHARACTERISTICS OF LUPUS NEPHRITIS IN EASTERN ZONE OF INDIA: A SINGLE TERTIARY CENTER EXPERIENCE

Objective: Lupus nephritis (LN) is the most common and serious manifestation of systemic lupus erythematosus (SLE) and an important cause of morbidity and mortality. Although diagnosis of LN is straight forward in a patient with SLE and proteinuria, and active urine sediment and perhapsrenal insufficiency, still renal biopsies are required at diagnosis to enable classification of nephritis severity, to provide prognostic information, and toguide treatment. Hence, the objective of this study is to determine the frequency of distribution of different classes of LN based on renal biopsy reports and to correlate it with various laboratory findings.Methods: Retrospective study was done in all patients with LN who had at least one representative renal biopsy and evaluated in NephrologyDepartment of SCB Medical College, Cuttack, in 6-month duration. Various laboratory values were recorded and correlated with histopathologicallupus classifications.Results: Out of 35 patients enrolled, 33 (94.28%) were females and 2 (5.71%) were males. Mean age was 27.53±12.26 years. Majority of cases belong to Class IV followed by Class V. Patients of Class IV LN have a significantly low hemoglobin level. Similarly, serum urea and creatinine are higher in Group IV than other groups, and serum creatinine was found to be significant. 24 hrs urinary protein excretion has a significant correlation with the classes of LN.Conclusion: This study suggests some meaningful correlation between laboratory findings and histopathological lupus classification. This study alsosuggests that renal biopsies are still beneficial for better evaluation of renal status and determination of LN classes.Keywords: Clinico-pathological correlation, Lupus nephritis, Biopsy

Occurrence & nucleotide sequence analysis of hepatitis G virus in patients with acute viral hepatitis & fulminant hepatitis

Background & objectives: Association of hepatitis G virus (HGV) with acute viral hepatitis (AVH) and fulminant hepatitis (FH) is not clearly understood.This study was designed to asses the occurrence of HGV infection and its relationship with other hepatotropic viruses in patients with FH and AVH and also to determine the nucleotide sequence of HGV isolates. Methods: The study included 100 patients of FH and 125 of AVH on the basis of clinical examination, liver function test and serology for hepatitis A, B, C and E virus. HGV RNA was detected by reverse transcriptase-polymerase chain reaction (RT-PCR) and direct sequencing for 4 randomly selected samples followed by phylogenetic analysis. Results: Of the 100 patients with FH, 30 were negative for hepatitis viruses A, B, C and E by serology (non A - non E) while 60 were negative in the AVH group. In the non A- non -E hepatitis group, HGV was positive in 16.66 per cent (5/30) cases of FH, 10 per cent (6/60) cases of AVH and 6 per cent (6/100) of healthy controls. The difference in HGV seropositivity between FH and AVH patients was statistically not significant compared to healthy controls, while HBV and HCV infections were significant. The four isolates sequenced seemed to be of same type and close to Chinese strain of HGV (Y13755.1 Y13756.1 Y15407, and U67782) on phylogeny. Interpretation & conclusion: In HGV infection was not found to be clinically significant as well as nonpathogenic in the patients of FH and AVH and appeared to be an innocent bystander in the course of the disease. The four sequenced HGV isolates showed close pairing with Chinese strains

Genetic diversity analysis in tossa jute (Corchorus olitorius L.) germplasm lines

An experiment was conducted to examine the magnitude of genetic diversity and characters contributing to genetic diversity among 81 tossa jute genotypes. Cluster analysis based on Euclidean squared distances and ward’s method, the genotypes were grouped into ten distinct clusters. Analysis reveals that stick weight contributes maximum to the phenotypic diversity (65.52%) followed by green weight (13.64%) and fibre yield (10.10%). Among the clusters Cluster IX recorded highest mean fibre yield (19.91g) followed by Cluster VII (18.94g) and these clusters also recorded high mean values for plant height, basal diameter, green weight and stick weight. The highest inter- cluster distance was 186.80 (between clusters II and X) followed by 161.26 (between clusters IV and X), indicating the wide genetic diversity among these clusters. The highest intra-cluster distance was observed in cluster II (20.34) and the lowest in cluster X (3.17). The average inter-cluster distances were higher than the average intra-cluster distances, which shows the presence of wide genetic diversity among the genotypes of different clusters than those of the same cluster. The first two principal components, whose Eigen values are greater than one, accounted for 74% of the total variation among the five characters. The information obtained from diversity analysis is useful in planning further breeding programme for tossa jute improvement

Class of self-limiting growth models in the presence of nonlinear diffusion

The source term in a reaction-diffusion system, in general, does not involve explicit time dependence. A class of self-limiting growth models dealing with animal and tumor growth and bacterial population in a culture, on the other hand are described by kinetics with explicit functions of time. We analyze a reaction-diffusion system to study the propagation of spatial front for these models.Comment: RevTex, 13 pages, 5 figures. To appear in Physical Review

Probing ultrafast carrier dynamics and nonlinear absorption and refraction in core-shell silicon nanowires

We investigate the relaxation dynamics of photogenerated carriers in silicon nanowires consisting of a crystalline core and a surrounding amorphous shell, using femtosecond time-resolved differential reflectivity and transmission spectroscopy at photon energies of 3.15 eV and 1.57 eV. The complex behavior of the differential transmission and reflectivity transients is the mixed contributions from the crystalline core and the amorphous silicon on the nanowire surface and the substrate where competing effects of state filling and photoinduced absorption govern the carrier dynamics. Faster relaxation rates are observed on increasing the photo-generated carrier density. Independent experimental results on crystalline silicon-on-sapphire help us in separating the contributions from the carrier dynamics in crystalline core and the amorphous regions in the nanowire samples. Further, single beam z-scan nonlinear transmission experiments at 1.57 eV in both open and close aperture configurations yield two-photon absorption coefficient \$beta$ (~3 cm/GW) and nonlinear refraction coefficient \$gamma$ (-2.5x10^-4 cm2/GW).Comment: 6 pages, 6 figure

Evidence of Coronavirus (CoV) Pathogenesis and Emerging Pathogen SARS-CoV-2 in the Nervous System: A Review on Neurological Impairments and Manifestations.

The coronavirus disease 2019 (COVID-19) pandemic is an issue of global significance that has taken the lives of many across the world. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the virus responsible for its pathogenesis. The pulmonary manifestations of COVID-19 have been well described in the literature. Initially, it was thought to be limited to the respiratory system; however, we now recognize that COVID-19 also affects several other organs, including the nervous system. Two similar human coronaviruses (CoV) that cause severe acute respiratory syndrome (SARS-CoV-1) and Middle East respiratory syndrome (MERS-CoV) are also known to cause disease in the nervous system. The neurological manifestations of SARS-CoV-2 infection are growing rapidly, as evidenced by several reports. There are several mechanisms responsible for such manifestations in the nervous system. For instance, post-infectious immune-mediated processes, direct virus infection of the central nervous system (CNS), and virus-induced hyperinflammatory and hypercoagulable states are commonly involved. Guillain-Barré syndrome (GBS) and its variants, dysfunction of taste and smell, and muscle injury are numerous examples of COVID-19 PNS (peripheral nervous system) disease. Likewise, hemorrhagic and ischemic stroke, encephalitis, meningitis, encephalopathy acute disseminated encephalomyelitis, endothelialitis, and venous sinus thrombosis are some instances of COVID-19 CNS disease. Due to multifactorial and complicated pathogenic mechanisms, COVID-19 poses a large-scale threat to the whole nervous system. A complete understanding of SARS-CoV-2 neurological impairments is still lacking, but our knowledge base is rapidly expanding. Therefore, we anticipate that this comprehensive review will provide valuable insights and facilitate the work of neuroscientists in unfolding different neurological dimensions of COVID-19 and other CoV associated abnormalities