1,828 research outputs found

    Collective enhancement and suppression in Bose-Einstein condensates

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    The coherent and collective nature of Bose-Einstein condensate can enhance or suppress physical processes. Bosonic stimulation enhances scattering in already occupied states which leads to atom amplification, and the suppression of dissipation leads to superfluidity. In this paper, we review several experiments where suppression and enhancement have been observed and discuss the common roots of and differences between these phenomena.Comment: ICAP proceedings; 12 figure

    Intramuscular (infiltrating) Lipoma

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    Intraoral lipomas are benign and relatively rare tumors, although they occur with higher frequencies in other areas, most especially the back, abdomen and shoulders of adults. They have no gender predilection and predominantly affect the buccal mucosa. This paper describes a case of intramuscular (infiltrating) lipoma on the buccal mucosa of a 60-year old male which is relatively rare when compared to simple lipoma of buccal mucosa, and review pertinent literature

    Gravity and Yang-Mills theory

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    Three of the four forces of Nature are described by quantum Yang-Mills theories with remarkable precision. The fourth force, gravity, is described classically by the Einstein-Hilbert theory. There appears to be an inherent incompatibility between quantum mechanics and the Einstein-Hilbert theory which prevents us from developing a consistent quantum theory of gravity. The Einstein-Hilbert theory is therefore believed to differ greatly from Yang-Mills theory (which does have a sensible quantum mechanical description). It is therefore very surprising that these two theories actually share close perturbative ties. This article focuses on these ties between Yang-Mills theory and the Einstein-Hilbert theory. We discuss the origin of these ties and their implications for a quantum theory of gravity.Comment: 6 pages, based on contribution to GRF 2010, to appear in a special edition of IJMP

    Thermal energy storage systems using fluidized bed heat exchangers

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    The viability of using fluidized bed heat exchangers (FBHX) for thermal energy storage (TES) in applications with potential for waste heat recovery was investigated. Of the candidate applications screened, cement plant rotary kilns and steel plant electric arc furnaces were identified, via the chosen selection criteria, as having the best potential for successful use of FBHX/TES system. A computer model of the FBHX/TES systems was developed and the technical feasibility of the two selected applications was verified. Economic and tradeoff evaluations in progress for final optimization of the systems and selection of the most promising system for further concept validation are described

    Kernel solutions of the Kostant operator on eight-dimensional quotient spaces

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    After introducing the generators and irreducible representations of the su(5){\rm su}(5) and so(6){\rm so}(6) Lie algebras in terms of the Schwinger's scillators, the general kernel solutions of the Kostant operators on eight-dimensional quotient spaces su(5)/su(4)×u(1){\rm su}(5)/{\rm su}(4)\times {\rm u}(1) and so(6)/so(4)×so(2){\rm so}(6)/{\rm so}(4)\times {\rm so}(2) are derived in terms of the diagonal subalgebras su(4)×u(1){\rm su}(4)\times {\rm u}(1) and so(4)×so(2){\rm so}(4)\times {\rm so}(2), respectively.Comment: 13 pages. Typos correcte

    Network approach towards understanding the crazing in glassy amorphous polymers

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    We have used molecular dynamics to simulate an amorphous glassy polymer with long chains to study deformation mechanism of crazing and associated void statistics. The Van der Waals interactions and the entanglements between chains constituting the polymer play a crucial role in crazing. Thus, we have reconstructed two underlying weighted networks, namely, the Van der Waals network and the Entanglement network from polymer configurations extracted from the molecular dynamics simulation. Subsequently, we have performed graph-theoretic analysis of the two reconstructed networks to reveal the role played by them in crazing of polymers. Our analysis captured various stages of crazing through specific trends in the network measures for Van der Waals networks and entanglement networks. To further corroborate the effectiveness of network analysis in unraveling the underlying physics of crazing in polymers, we have contrasted the trends in network measures for Van der Waals networks and entanglement networks in the light of stress-strain behaviour and voids statistics during deformation. We find that Van der Waals network plays a crucial role in craze initiation and growth. Although, the entanglement network was found to maintain its structure during craze initiation stage, it was found to progressively weaken and undergo dynamic changes during the hardening and failure stages of crazing phenomena. Our work demonstrates the utility of network theory in quantifying the underlying physics of polymer crazing and widens the scope of applications of network science to characterization of deformation mechanisms in diverse polymers.Comment: 19 pages, 8 figures, supplementary information (SI) available from authors upon reques

    Bright and dark plasmon resonances of nanoplasmonic antennas evanescently coupled with a silicon nitride waveguide

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    In this work we investigate numerically and experimentally the resonance wavelength tuning of different nanoplasmonic antennas excited through the evanescent field of a single mode silicon nitride waveguide and study their interaction with this excitation field. Experimental interaction efficiencies up to 19% are reported and it is shown that the waveguide geometry can be tuned in order to optimize this interaction. Apart from the excitation of bright plasmon modes, an efficient coupling between the evanescent field and a dark plasmonic resonance is experimentally demonstrated and theoretically explained as a result of the propagation induced phase delay.status: publishe

    Natural Dye Extracts of Areca Catechu Nut as dye Sensitizer for Titanium dioxide Based Dye Sensitized Solar Cells

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    A dye sensitized solar cell was fabricated using titanium dioxide nano particles sensitized by a new natural dye extracted from areca catechu nut. The natural dye extract contains tannin which is rich in gallotannic acid. The pure titanium dioxide nano particles in anatase phase were synthesized by sol-gel technique and were sensitized by the natural dye to yield photo anode material. The Powder X-Ray Diffraction, UV-vis spectra, Fourier Transform Infra Red spectroscopy, Energy Dispersive X- Ray spectroscopy and Scanning Electron Microscopy studies of pure and natural dye sensitized TiO2 were carried out to analyze their structural, optical, functional group, compositional and morphological details. The dye sensitized solar cell was fabricated using TiO2 nano particles coated on FTO glass plate which is sensitized by the natural dye as photo anode and platinum coated FTO as counter electrode. The natural dye sensitized solar cell showed a solar light energy to electron conversion efficiency of 0.76 %. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3431

    Impact of Selenium Nanoparticles on Growth, Biochemical Characteristics and Yield of Cluster Bean Cyamopsis tetragonoloba

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    The present study deals with the impact of selenium nanoparticles on growth, biochemical characteristics and yield of Cluster bean Cyamopsis tetragonoloba grown for a period 60 days Sodium selenite and ascorbic acid was utilized for the synthesis of Selenium nanoparticles using precipitation method. Selenium nanoparticles were characterized by using SEM, EDAX, FTIR and XRD. Pot culture studies of cluster bean in different quantity of Selenium nanoparticles such as 0,100, 200, 300, 400 and 500mg for treatment T0 (Control) T1, T2, T3, T4 and T5 and growth biochemical and yield were estimated at the end of 60 days. SEM image of selenium nanoparticles was observed as spherical in shape. EDAX spectrum recorded on purity of selenium nanoparticles. The FTIR spectrum of selenium nanoparticles was analyzed in the range of 4000-400 cm-1 spectral bands were observed. The germination percentage in T0, T1, T2, T3, T4 and T5 are 100,90,80,90,100 and 100 respectively. Among the treatments the shoot length is higher (21.8) in T1 containing 100mg of selenium nanoparticles and lower in(12.01) T5 containing 500mg of nanoparticles. Root length, fresh and dry weight and leaf area were higher in T2. The vigor index is higher T4.The chlorophyll a, b total Chlorophyll, carotenoids, anthocyanin, protein, L-proline, free amino acids and leaf nitrate were higher inT4.Among the treatments yield of cluster bean is higher in T4 and lower in T0
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