A survey on fiber nonlinearity compensation for 400 Gbps and beyond optical communication systems

Optical communication systems represent the backbone of modern communication networks. Since their deployment, different fiber technologies have been used to deal with optical fiber impairments such as dispersion-shifted fibers and dispersion-compensation fibers. In recent years, thanks to the introduction of coherent detection based systems, fiber impairments can be mitigated using digital signal processing (DSP) algorithms. Coherent systems are used in the current 100 Gbps wavelength-division multiplexing (WDM) standard technology. They allow the increase of spectral efficiency by using multi-level modulation formats, and are combined with DSP techniques to combat the linear fiber distortions. In addition to linear impairments, the next generation 400 Gbps/1 Tbps WDM systems are also more affected by the fiber nonlinearity due to the Kerr effect. At high input power, the fiber nonlinear effects become more important and their compensation is required to improve the transmission performance. Several approaches have been proposed to deal with the fiber nonlinearity. In this paper, after a brief description of the Kerr-induced nonlinear effects, a survey on the fiber nonlinearity compensation (NLC) techniques is provided. We focus on the well-known NLC techniques and discuss their performance, as well as their implementation and complexity. An extension of the inter-subcarrier nonlinear interference canceler approach is also proposed. A performance evaluation of the well-known NLC techniques and the proposed approach is provided in the context of Nyquist and super-Nyquist superchannel systems.Comment: Accepted in the IEEE Communications Surveys and Tutorial

Studies on Phytochemical constituents, Functional Group Identification and Antimicrobial Activity of Solanum nigrum (Solanaceae)

Phytochemical constituents, functional group identification and antimicrobial activity of ethanolic extract of Solanum nigrum were investigated. The phytochemical screening of the crude extract revealed the presence of alkaloids, reducing sugars, tannis, flavonoids, Phlobatannis, and steriods. The extract were subjected for identification of functional groups using infra red spectrophotometer, presence of C=O, C-H, C=C and CO were identified, these bonding structures are responsible for presence of alkyl groups, methyl groups, alcohols, ethers, esters, carboxylic acid and anhydrides. And the crude ethanolic extract of Solanum nigrum were assayed for in vitro antimicrobial activity against gram positive and gram negative bacteria and they were also subjected for antifungal activity and the zone of inhibition were compared with control drug Penicillin and Nystatin. Staphylococcus aureus as the most sensitive strains exhibited maximum zone of inhibition about 25.7mm among gram positive organism tested. Escherichia coli exhibits 30.1mm zone than that of standard penicillin positive control. Trichophyton mentagrophytes exhibits maximum zone of inhibition of about 26.1mm among the tested fungal species

ENVIRONMENTAL IMPACT ASSESSMENT OF DISPOSAL SITE POLLUTION ON GROUNDWATER QUALITY OF SALEM CITY, TAMILNADU

Analysis of Ground Water Quality Parameters of water samples from three boreholes located near a dumping site and one borehole located near a landfilling site at Salem, Tamilnadu. It was carried out to ascertain the magnitude of dumpsite pollution on groundwater quality. Borehole locations were at radial distances of 10km away from the landfill and dumping site respectively. Groundwater samples were collected from all the said four sites and tested for major water quality parameters. The parameters determined to included: Chlorides, Total Hardness, Fluorides, pH and Dissolved oxygen (D.O.). Most of these parameters indicated traceable pollution but were below the World Health Organization (WHO) and Bureau of Indian Standard (BIS) for Drinking Water Quality limits for consumption. Our assessment focuses on the groundwater contamination potentials of both dumping and sanitary landfilling methods. In Salem city, solid waste disposal is done in various locations. Four different sites, namely New Bus Stand, Dalmia Board and Kitchipalayam where mere dumping of solid waste is practiced and Chettichavadi where a landfill site is operated were chosen for our study. The results portray significant contamination of groundwater. The obtained results have been analyzed further in the light of Environmental Impact Assessment concepts. Many-fold increase in the concentration of all constituents is noticed. An Incremental increase in the concentration of constituents of groundwater in and around the waste disposal sites, both in space and time (present and future), has been determined. It shows that the rate of deterioration in the quality of groundwater is alarming, if the same practice of irregular dumping of municipal solid waste is continued

Carer Supports in Reading-Writing for Children with Learning Difficulties: An Exploratory Cross-Sectional Pilot Survey

When carers are involved in the reading-writing activities of their children at home, their academic performance shows improvement. In this study, a descriptive exploratory survey research design is used to evaluate the nature, type, length, quality, quantity, extensity, and intensity of such carer supports. Following a six-step tool development process, including a review of the relevant tools, and expert validation, an investigator-designed 10-item unstructured questionnaire was administered through open-ended interviews with a random sample of 143 carers of 120 students (comprised of 60 boys and 60 girls in the age group of 6-15 years) suspected of academic difficulties. The derived data in the form of yes/no responses and descriptive narrations by carers was recorded, content-analyzed, coded, scored, and collaboratively evaluated as frequency counts, percentages, and inferential non-parametric statistics. The results were analysed for key parameters like (i) place of study; (ii) time of study; (iii) study materials; (iv) initiation to study; (v) availability of support; (vi) timetable or curriculum; (vii) supervision; (viii) extracurricular activities; (ix) gadget use; and, (x) future goals. The findings are profiled, discussed, and highlighted along with recommended remedies in light of their implications or utility for reading-writing in such affected children. Keywords: Parents, home settings, study habits, gadget use DOI: 10.7176/JEP/14-24-05 Publication date:August 31st 202

Identification of Phytochemical Constituents of Aegle marmelos Responsible for Antimicrobial Activity against Selected Pathogenic Organisms

Antimicrobial activity and phytochemical constituents of an ethanolic extract of Aegle marmelos were investigated. The phytochemical screening of the crude extract revealed the presence of Alkaloids, Cardiac glycosides, Terpenoids, Saponins, Tannis, Flavonoids, and Steroids. The crude ethanolic extract was tested for antimicrobial activity against gram positive organisms of Bacillus subtilis (NCIM: 3471), Staphylococcus aureus (NCIM: 2079), gram negative Escherichia coli (NCIM: 2065) and Pseudomonas aeruginosa (NCIM: 2200) at different concentrations levels of 0.5, 1.0, 1.5, 2.0 and 2.5 mg/ml. At the 2.5 mg/ml concentration, gram negative Escherichia coli exhibits a zone of inhibition about 25.7mm; Pseudomonas aeruginosa 19.9mm; gram positive Staphylococcus aureus 29.0 mm; and Bacillus subtilis, a maximum zone of inhibition about 28.1 mm as compared to the control drug penicillin. Escherichia coli, Pseudomonas aeruginosa and Bacillus subtilis exhibit a maximum zone of inhibition, hence they were considered as susceptible to the plant extracts but Staphylococcus aureus doesn’t exhibit such a zone of inhibition and is therefore considered as resistant

Operational mesoscale atmospheric dispersion prediction using a parallel computing cluster

An operational atmospheric dispersion prediction system is implemented on a cluster supercomputer for Online Emergency Response at the Kalpakkam nuclear site. This numerical system constitutes a parallel version of a nested grid meso-scale meteorological model MM5 coupled to a random walk particle dispersion model FLEXPART. The system provides 48-hour forecast of the local weather and radioactive plume dispersion due to hypothetical airborne releases in a range of 100 km around the site. The parallel code was implemented on different cluster configurations like distributed and shared memory systems. A 16-node dual Xeon distributed memory gigabit ethernet cluster has been found sufficient for operational applications. The runtime of a triple nested domain MM5 is about 4h for a 24h forecast. The system had been operated continuously for a few months and results were ported on the IMSc home page. Initial and periodic boundary condition data for MM5 are provided by NCMRWF, New Delhi. An alternative source is found to be NCEP, USA. These two sources provide the input data to the operational models at different spatial and temporal resolutions using different assimilation methods. A comparative study on the results of forecast is presented using these two data sources for present operational use. Improvement is noticed in rainfall forecasts that used NCEP data, probably because of its high spatial and temporal resolution

Antimicrobial Activity of Aegle marmelos Against Pathogenic Organism Compared with Control Drug

The aqueous and ethanolic extracts from the leaves of Aegle marmelos traditionally used in Indian system of Medicines were screened against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis by using disc diffusion test technique. Bacillus subtilis exhibit about 22mm inhibition zone were considered resistant. The zone of inhibition of the extract was compared with the standard antibiotics such as Penicillin. The study suggests that the plant is promising development of phytomedicine for antimicrobial properties

A recurrent case of pyruvate dehydrogenase complex deficiency

Pyruvate dehydrogenase complex deficiency is an inherited inborn error of metabolism causing lactic acidosis and several neurological symptoms. Its incidence and prevalence are not known. Here we report about a child with global developmental delay, central hypotonia and dyskinesia. Sanger sequencing was done and found to have homozygous nonsense mutation in exon 4 of PDHX gene causing lactic acidosis. In the next pregnancy selective Sanger variant analysis was carried out and the fetus was also found to be affected with the same genetic defect. Hence medical termination of Pregnancy was carried out. We conclude that early selective genetic testing will prevent further affected births

Room temperature ferromagnetism in chemically synthesized ZnO rods

We report structural and magnetic properties of pure ZnO rods using X-ray diffraction (XRD), magnetization hysteresis (M-H) loop and near edge x-ray fine structure spectroscopy (NEXAFS) study at O K edge. Sample of ZnO was prepared by co-precipitation method. XRD and selective area electron diffraction measurements infer that ZnO rods exhibit a single phase polycrystalline nature with wurtzite lattice. Field emission transmission electron microscopy, field emission scanning electron microscopy micrographs infers that ZnO have rod type microstructures with dimension 200 nm in diameter and 550 nm in length. M-H loop studies performed at room temperature display room temperature ferromagnetism in ZnO rods. NEXAFS study reflects absence of the oxygen vacancies in pure ZnO rods.Comment: 8 Pages, 3 Figure