8,656 research outputs found

    A possible shock effect associated with seaquakes

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    The effects of earthquakes felt on board vessels at sea are discussed along with the possibility of cohesive shock wave propagating through the ocean. The large earthquake of shallow focus which occurred on 29 April 1970, in the Guatemala Basin is analyzed. The thermal information recorded by ITOS-1 spacecraft showed an anomalous temperature enhancement of +3 K in the immediate vicinity, indicating a thermal effect attributed to shock waves

    WESTERNIZATION IN CHINA: A CASE STUDY IN PROCESSED POTATOES

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    Keywords: China, potatoes, westernization, food demand, convenience foods Abstract: The demand for convenience foods is growing around the world, especially in China. However, the contributing factors of this change in food preferences are still largely unknown. To measure this westernization trend, data from a survey of Chinese consumers in Beijing is evaluated using a multinomial ordered logit model to determine which consumer attributes influence the probability of consuming western foods such as French fries, mashed potatoes, and potato chips. Results show that higher income levels and positive opinions concerning western food taste have a significant influence on increased consumption of all three processed potato products. Additionally, younger ages and female gender were highly significant indicators of increased French fry and potato chip consumption.Crop Production/Industries,

    Chiral Symmetry Breaking in Quenched Massive Strong-Coupling QED4_4

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    We present results from a study of subtractive renormalization of the fermion propagator Dyson-Schwinger equation (DSE) in massive strong-coupling quenched QED4_4. Results are compared for three different fermion-photon proper vertex {\it Ans\"{a}tze\/}: bare γμ\gamma^\mu, minimal Ball-Chiu, and Curtis-Pennington. The procedure is straightforward to implement and numerically stable. This is the first study in which this technique is used and it should prove useful in future DSE studies, whenever renormalization is required in numerical work.Comment: REVTEX 3.0, 15 pages plus 7 uuencoded PostScript figure

    Effect of dislocations on properties of heteroepitaxial InP solar cells

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    The apparently unrelated phenomena of temperature dependency, carrier removal and photoluminescence are shown to be affected by the high dislocation densities present in heteroepitaxial InP solar cells. Using homoepitaxial InP cells as a baseline, it is found that the relatively high dislocation densities present in heteroepitaxial InP/GaAs cells lead to increased volumes of dVoc/dt and carrier removal rate and substantial decreases in photoluminescence spectral intensities. With respect to dVoc/dt, the observed effect is attributed to the tendency of dislocations to reduce Voc. Although the basic cause for the observed increase in carrier removal rate is unclear, it is speculated that the decreased photoluminescence intensity is attributable to defect levels introduced by dislocations in the heteroepitaxial cells

    Effect of Wavefunction Renormalisation in N-Flavour Qed3 at Finite Temperature

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    A recent study of dynamical chiral symmetry breaking in N-flavour QED3_3 at finite temperature is extended to include the effect of fermion wavefunction renormalisation in the Schwinger-Dyson equations. The simple ``zero-frequency'' truncation previously used is found to lead to unphysical results, especially as T0T \to 0. A modified set of equations is proposed, whose solutions behave in a way which is qualitatively similar to the T=0T=0 solutions of Pennington et al. [5-8] who have made extensive studies of the effect of wavefunction renormalisation in this context, and who concluded that there was no critical NcN_c (at T=0) above which chiral symmetry was restored. In contrast, we find that our modified equations predict a critical NcN_c at T0T \not= 0, and an NTN-T phase diagram very similar to the earlier study neglecting wavefunction renormalisation. The reason for the difference is traced to the different infrared behaviour of the vacuum polarisation at T=0T=0 and at T0T \not= 0.Comment: 17 pages + 13 figures (available upon request), Oxford preprint OUTP-93-30P, IFUNAM preprint FT94-39, LaTe

    Ultracompact monolithic integration of balanced, polarization diversity photodetectors for coherent lightwave receivers

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    The authors have monolithically integrated an optical front-end on InP for balanced, polarization-diversity coherent lightwave reception which is only 1.3-mm long. Low on-chip insertion loss (<4.5 dB) and balanced photoresponse (1.05:1 or better) are achieved at 1.5-μm wavelength using straightforward, regrowth-free fabrication. Low-capacitance photodetectors (≤0.15 pF) are employed for high bandwidth operation

    Large-scale Star Formation Triggering in the Low-mass Arp 82 System: A Nearby Example of Galaxy Downsizing Based on UV/Optical/Mid-IR Imaging

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    As part of our Spitzer Spirals, Bridges, and Tails project to help understand the effects of galaxy interactions on star formation, we analyze GALEX ultraviolet, SARA optical, and Spitzer infrared images of the interacting galaxy pair Arp 82 (NGC 2535/6) and compare to a numerical simulation of the interaction. We investigate the multiwavelength properties of several individual star forming complexes (clumps). Using optical and UV colors, EW(Halpha), and population synthesis models we constrain the ages of the clumps and find that the median clump age is about 12 Myr. The clumps have masses ranging from a few times 10^6 to 10^9 solar masses. In general, the clumps in the tidal features have similar ages to those in the spiral region, but are less massive. The 8 micron and 24 micron luminosities are used to estimate the far-infrared luminosities and the star formation rates of the clumps. The total clump star formation rate is 2.0+/-0.8 solar masses per year, while the entire Arp 82 system is forming stars at a rate of 4.9+/-2.0 solar masses per year. We find, for the first time, stars in the HI arc to the southeast of the NGC 2535 disk. Population synthesis models indicate that all of the observed populations have young to intermediate ages. We conclude that although the gas disks and some old stars may have formed early-on, the progenitors are late-type or low surface brightness and the evolution of these galaxies was halted until the recent encounter.Comment: Accepted for publication in the AJ, 22 Figures, 5 Table

    Permanent-magnet atom chips for the study of long, thin atom clouds

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    Atom-chip technology can be used to confine atoms tightly using permanently magnetised videotape along with external magnetic fields. The one-dimensional (1D) gas regime can be realised and studied by trapping the atoms in high-aspect-ratio traps in which the radial motion of the system is confined to zero-point oscillation

    ONE LOOP QED VERTEX IN ANY COVARIANT GAUGE: ITS COMPLETE ANALYTIC FORM

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    The one loop vertex in QED is calculated in arbitrary covariant gauges as an analytic function of its momenta. The vertex is decomposed into a longitudinal part, that is fully responsible for ensuring the Ward and Ward-Takahashi identities are satisfied, and a transverse part. The transverse part is decomposed into 8 independent components each being separately free of kinematic singularities in any\bf any covariant gauge in a basis that modifies that proposed by Ball and Chiu. Analytic expressions for all 11 components of the O(α){O(\alpha)} vertex are given explicitly in terms of elementary functions and one Spence function. These results greatly simplify in particular kinematic regimes.Comment: 35 pages, latex, 2 figures, Complete postscript file available from: ftp://cpt1.dur.ac.uk/pub/preprints/dtp95/dtp9506/dtp9406.p
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