565 research outputs found

    Nonlinear Effects and Multisolitons in Metamaterials

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    AbstractIn this paper, we outline a novel class of materials, called metamaterials, with negative refractive index and a high degree of nonlinearity. A brief summary is given on the basic theory of optics to show how this condition arrives for metamaterials to be designed into an antenna with split-ring-resonator (SRR). An example is given on the modeling of such SRR-based metamaterials. On a continuum Hamiltonian, a Klein-Gordon equation was derived which gave rise to both dark and bright solitons that showed interesting behavior against nondimensional time, even to the extent of revealing bi- and tri-breathers

    Rearing of Labeo bata in sewage-fed fish culture pond

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    Labeo bata is a highly priced fish which commanding good consumer preference, even if the size is very small (15 to 20 g each), especially in West Bengal. With a view to evaluating the culture potential of this fish, repeated experiments were conducted at the Wastewater Aquaculture Division of the Central Institute of Freshwater Aquaculture, Rahara, West Bengal, during 1991-93 in ponds fed with treated domestic sewage effluent. An average production of 1270.63 kg per ha was obtained within 6 to 10 months for a uniform stocking density of 50,000 seed per ha. The average size attained by the fish in the different sets of experiments varied from 23.3 to 37.9 g as against the initial weight of 0.096 to 0.193 g. Details of management, growth, survival, quantity of sewage used and pond nutrient status and productivity are dealt with in this communication


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    Prostaglandins (PG) are present in different tissues specially in brain tissues endowed with different central nervous system activities. Similarly, 5-hydroxytryptamine (5-HT) a biogenic amine with its presence in different central and peripheral tissues as neurotransmitter plays an important role in the regulation of physiological functions specially hypnosis, convulsions, analgesia in rats, mice, cats and chicks etc. Pentobarbitone (PB) induced sleep appear to be a serotonergic modulator activity in different animals. PGE1 potentiates the pentobarbitone hypnosis also mediated through serotonin. In the present study, PGE1 induced sleeping time in chicks was evaluated. Drugs affecting 5-HT synthesis, metabolism and receptor activity modulate the potentiating response, while adrenergic receptor antagonists did not showed any response. This study suggest that PGE1 potentiate PB induced sleep through serotonergic signaling pathway as PGE1 increased 5-HT synthesis rate in chick brain

    Web Usage Mining: A Survey on Pattern Extraction from Web Logs

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    As the size of web increases along with number of users, it is very much essential for the website owners to better understand their customers so that they can provide better service, and also enhance the quality of the website. To achieve this they depend on the web access log files. The web access log files can be mined to extract interesting pattern so that the user behaviour can be understood. This paper presents an overview of web usage mining and also provides a survey of the pattern extraction algorithms used for web usage mining

    Distortion Analysis of Thin-Walled Investment Castings

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    Dokra casting is famous for its Artistic value to the world but it is also sophisticated engineering. The technique is almost 4500 years old. It is practiced by the tribal artisans of India. It is a clay moulded wax-based thin-walled investment casting technique where liquid metal was poured into the red hot mould. Dimensional accuracy is always preferable for consumers of any product. Distortion is one of the barriers to achieving the accurate dimension for this type of casting especially for the bending parts. The cause and nature of the distortion for this type of casting must be analyzed to design a product with nominal tolerance and dimensional accuracy

    Diffusion with rearranging traps

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    A model for diffusion on a cubic lattice with a random distribution of traps is developed. The traps are redistributed at certain time intervals. Such models are useful for describing systems showing dynamic disorder, such as ion-conducting polymers. In the present model the traps are infinite, unlike an earlier version with finite traps, this model has a percolation threshold. For the infinite trap version a simple analytical calculation is possible and the results agree qualitatively with simulation.Comment: Latex, five figure

    Verbreitung und Biomasseerzeugungspotential von salz beeinflussten Böden in Indien

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    Die Versalzung des Bodens und Grund-wassers stellt eine der größten Herausforderungen für die Landwirtschaft in ariden und semiariden Gebieten dar. In Folge der Anreicherung von leicht löslichen Salzen, im Wurzelraum, werden die Erträge der Kulturpflanzen signifikant reduziert oder fallen komplett aus. Integrierte Lösungen sind gefragt, die dauerhaft eine nachhaltige, positive Auswirkung auf die Boden-fruchtbarkeit haben und dazu beitragen, das versalzte Ödland wieder nutzbar zu machen. Eine alternative Lösung stellen Agroforstwirtschaftliche Systeme mit multi-funktionalen salz toleranten Baumarten, die eine wesentlich höhere Salztoleranz als die Kulturpflanzen haben, dar. Leguminose Baumarten wie Acacia nilotica und Prosopis juliflora wachsen schnell und können nicht nur als Brennholz oder Baumaterial benutzt werden, sondern auch Hülsenfrüchte tragen, die als Futter oder sogar Nahrung verwendet werden können. Ihre positive ökologische Rolle auf die Bodeneigenschaften, durch Akkumulation von organischer Substanz, Boden-strukturauflockerung und Grundwasser-senkung, ist bekannt. Allerdings ist das Potential des Salzödlandes für die Biomasseerzeugung auf regionaler Skala noch nicht ausreichend erforscht. Im Rahmen des Forschungsprojektes BIOSAFOR, finanziert von der Europäischen Kommission, werden verschiedene Agroforstsysteme für versalzte Böden entwickelt und eine Evaluierung der biophysikalischen Eignung des Ödlandes für die Biomasseproduktion auf Landes- und Staatsebene für Indien durchgeführt. Land Suitability Classification (LSC) der FAO erfolgt auf Staatsebene. Die wichtigsten limitierenden klimatischen, Boden- und Grundwasserparameter werden berücksichtigt, um die Standorteignung für die Biomasseproduktion zu ermitteln

    Effects of Bt-cotton on biological properties of Vertisols in central India

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    Growing areas under transgenic crops have created a concern over their possible adverse impact on the soil ecosystem. This study evaluated the effect of Bt-cotton based cropping systems on soil microbial and biochemical activities and their functional relationships with active soil carbon pools in Vertisols of central India (Nagpur, Maharastra, during 2012–2013). Culturable groups of soil microflora, enzymatic activities and active pools of soil carbon were measured under different Bt-cotton based cropping systems (e.g. cotton-soybean, cotton-redgram, cotton-wheat, cotton-vegetables and cotton-fallow). Significantly higher counts of soil heterotrophs (5.7–7.9 log cfu g−1soil), aerobic N-fixer (3.9–5.4 log cfu g−1soil) and P-solubilizer (2.5−3.0 log cfu g−1soil) were recorded in Bt-cotton soils. Similarly, soil enzymatic activities, viz. dehydrogenase (16.6–22.67 µg TPF g−1 h−1), alkaline phosphatase (240–253 µg PNP g−1 h−1) and fluorescein di-acetate hydrolysis (14.6–18.0 µg fluorescein g−1 h−1), were significantly higher under Bt-cotton-soybean system than other Bt- and non-Bt-cotton based systems in all crop growth stages. The growth stage-wise order of soil microbiological activities were: boll development > harvest > vegetative stage. Significant correlations were observed between microbiological activities and active carbon pools in the rhizosphere soil. The findings indicated no adverse effect of Bt-cotton on soil biological properties

    Impact of genetically modified crops on rhizosphere microorganisms and processes:A review focusing on Bt cotton

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    In recent years, the cultivation of genetically modified (GM) crops has become a topic of great interest, due in part to the considerable public controversy, which exists concerning their potential benefits or adverse effects. Since the development of the first GM crop about 25 years ago, a diverse range of new cultivars have been released into the environment which were developed by employing advanced molecular techniques to introduce new beneficial genes from a wide variety of sources. While GM crops have great potential for enhancing agricultural production, their potential impacts on soil biota are only partially understood and information on their long-term impact on soil biota is scant. Several recent studies have indicated that GM crops may cause changes in both the invertebrate and microorganism soil biota associated with these crops, with some laboratory-based experiments even revealing transfer of genes from GM plants to native soil bacteria. However, processes such as gene transfer and stable inheritance to subsequent generations remain unproven in natural soil systems. In addition, although significant research efforts have recently been directed towards understanding the effects of GM crops on soil biota, the wide variation in the scientific observations has often hindered an accurate understanding of the issues. Thus, this review collated and synthesized all available information on the microbiological and biochemical effects of GM crops on soil biota with a special focus on GM Bt-cotton. The review also addressed the key issues associated with the use of GM crops including herbicide resistance, transgene flow and explored the plausibility of horizontal gene transfer in soil

    Synthesis and Optical Absorption Properties of Copper Oxide Nanoparticles for Applications in Transparent Surface Coatings and Solar Cells

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    A simple wet chemical method has been successfully deployed to synthesize CuO nanoparticles (NPs) by using copper chloride and lithium hydroxide as the precursors. X-ray diffraction study revealed that the synthesized CuO is highly crystalline and pure. The synthesized CuO NPs has very high transparency in the visible region of wavelength. The band gap of the CuO NPs was found to be 1.54 eV