753 research outputs found
Strichartz estimates for the water-wave problem with surface tension
Strichartz-type estimates for one-dimensional surface water-waves under
surface tension are studied, based on the formulation of the problem as a
nonlinear dispersive equation. We establish a family of dispersion estimates on
time scales depending on the size of the frequencies. We infer that a solution
of the dispersive equation we introduce satisfies local-in-time Strichartz
estimates with loss in derivative:
where depends on and on the norms of the
initial data in . The proof uses the frequency analysis
and semiclassical Strichartz estimates for the linealized water-wave operator.Comment: Fixed typos and mistakes. Merged with arXiv:0809.451
Experimental and numerical investigation of an air-to-water heat pipe-based heat exchanger
An experimental and analytical investigation was conducted on an air-to-water heat exchanger equipped with six wickless heat pipes (thermosyphons) charged with water as the working fluid. The flow pattern consisted of a double pass on the evaporator and condenser sections. The six thermosyphons were all made from carbon steel, measured 2m in length and were installed in a staggered arrangement.
The objectives of the reported experimental investigation were to analyse the effect of multiple air passes at different air inlet temperatures (100 to 250°C) and air mass flow rates (0.05 to 0.14kg/s) on the thermal performance of the heat exchanger unit including the heat pipes. The results were compared with a CFD model that assumed the heat pipes were solid rods with a constant conductivity. The conductivity of the pipes was extracted from modifications of correlations available in the literature based around the theory of Thermal Resistance. The results proved to be very accurate within 10% of the experimental values
On the Evolution Equation for Magnetic Geodesics
In this paper we prove the existence of long time solutions for the parabolic
equation for closed magnetic geodesics.Comment: In this paper we prove the existence of long time solutions for the
parabolic equation for closed magnetic geodesic
La relación personal en el tratamiento de la diversidad
El autor centra su aportación en diferentes características de los organismos vivos, para incorporarlas a las perspectivas interpretativas y operativas, y de los métodos actuales de intervención educativa. En el texto también se trata el enfoque positivo desde la dimensión técnica y no «voluntarista», teniendo en cuenta que los especialistas que adoptan la perspectiva del enfoque positivo dan mucha importancia al tema de la calidad de vida.L'autor centra la seva aportació en diferents característiques dels organismes vius, per incorporar- les a les perspectives interpretatives i operatives, i dels mètodes actuals d'intervenció educativa. Al text també es tracta l'enfocament positiu des de la seva dimensió tècnica i no «voluntarista», tenint en compte que els especialistes que adopten la perspectiva de l'enfocament positiu donen molta importància al tema de la qualitat de vida.The author focuses on the different characteristics of the alive organisms in order to include them into the interpretative and operative views of the current methods of educational intervention. He also deals with the positive focus, from the technical and «no voluntary» dimension, taking into account that those specialists having this kind of view do emphasize a lot on the quality of life issue
Political economy of oil production from 1850s to 1974
A study of the oil industry in its modern development from the 1850s to 1973. During this period the industry underwent significant changes in terms of its productive expansion, the diversity of its products, its role in general production, its corporate organisation and in terms of its significance to the very reproduction of advanced societies. The examination of the oil industry focuses on a political economy of its historical expansion. The thesis uses a Marxist theoretical framework to examine issues related to oil production as well as synthesising the elemental features of oil production into a structured conceptual model of the oil industry. The thesis divides the analysis of oil between chapters dealing with economic and political concerns in the context of historic epochs. The economic components of the thesis deal with the capitalist development of oil, its relationship with other sectors of production and consumption and an assessment of its role in economic growth as a whole. This provides the basis for the subsequent politically focused analyses. The political chapters deal with two primary issues, including the state response to the monopolisation of the oil industry and the effect of the expanding importance of oil on political relations. The analysis of the monopolisation of the oil industry provides an opportunity to study the relationship between the state in a regulatory function and the subsequent constraint on oil industry autonomy. The study of interstate relations focuses in turn on the effect of expanding oil production on the economic interests of states, in their support for the reproduction of capital in their domains
A Nanophotonic Structure Containing Living Photosynthetic Bacteria
Photosynthetic organisms rely on a series of self-assembled nanostructures with tuned electronic energy levels in order to transport energy from where it is collected by photon absorption, to reaction centers where the energy is used to drive chemical reactions. In the photosynthetic bacteria Chlorobaculum tepidum, a member of the green sulfur bacteria family, light is absorbed by large antenna complexes called chlorosomes to create an exciton. The exciton is transferred to a protein baseplate attached to the chlorosome, before migrating through the Fenna-Matthews-Olson complex to the reaction center. Here, it is shown that by placing living Chlorobaculum tepidum bacteria within a photonic microcavity, the strong exciton-photon coupling regime between a confined cavity mode and exciton states of the chlorosome can be accessed, whereby a coherent exchange of energy between the bacteria and cavity mode results in the formation of polariton states. The polaritons have energy distinct from that of the exciton which can be tuned by modifying the energy of the optical modes of the microcavity. It is believed that this is the first demonstration of the modification of energy levels within living biological systems using a photonic structure
Evaluation of true maximal oxygen uptake based on a novel set of standardized criteria
In this study, criteria are used to identify whether a subject has elicited maximal oxygen uptake. We evaluated the validity of traditional maximal oxygen uptake criteria and propose a novel set of criteria. Twenty athletes completed a maximal oxygen uptake test, consisting of an incremental phase and a subsequent supramaximal phase to exhaustion (verification phase). Traditional and novel maximal oxygen uptake criteria were evaluated. Novel criteria were: oxygen uptake plateau defined as the difference between modelled and actual maximal oxygen uptake >50% of the regression slope of the individual oxygen uptake-workrate relationship; as in the first criterion, but for maximal verification oxygen uptake; and a difference of [less than or equal to]4 beats x [min.sup.-1] between maximal heart rate values in the 2 phases. Satisfying the traditional oxygen uptake plateau criterion was largely an artefact of the between-subject variation in the oxygen uptake-workrate relationship. Secondary criteria, supposedly an indicator of maximal effort, were often satisfied long before volitional exhaustion, even at intensities as low as 61% maximal oxygen uptake. No significant mean differences were observed between the incremental and verification phases for oxygen uptake (t = 0.4; p = 0.7) or heart rate (t = 0.8; p = 0.5). The novel oxygen uptake plateau criterion, maximal oxygen uptake verification criterion, and maximal heart rate verification criterion were satisfied by 17, 18, and 18 subjects, respectively. The small individual absolute differences in oxygen uptake between incremental and verification phases observed in most subjects provided additional confidence that maximal oxygen uptake was elicited. Current maximal oxygen uptake criteria were not valid and novel criteria should be further explored
eta N S-wave scattering length in a three coupled channel, multiresonance, unitary model
The S-wave scattering length for eta-N elastic scattering is extracted from
the S-wave T-matrix in a three coupled channel, multiresonance unitary model.
Results are compared with values already reported in literature which are
obtained applying multichannel, but single resonance -- no background models. A
dispersion among the previously published values of the real part of the S-wave
scattering length is observed. We demonstrate that the reported spread
originates from the strong sensitivity of the scattering length upon the small
variation of the used input resonance parameters. In addition, we show that
eta-N scattering length value obtained in single resonance -- no background
models significantly increases if background term is added in a unitary way. We
question the reliability of previously reported values based only on the single
resonance -- no background models, and demonstrate that the value of the eta-N
S-wave scattering length obtained in this publication is much more realistic
because of the multiresonance and unitary approach.Comment: revtex, 20 pages + 3 figures (PostScript: gzip + uuencode) included,
submitted to Phys. Rev. C, brief Reports
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