18,336 research outputs found

    On the "Causality Paradox" of Time-Dependent Density Functional Theory

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    I show that the so-called causality paradox of time-dependent density functional theory arises from an incorrect formulation of the variational principle for the time evolution of the density. The correct formulation not only resolves the paradox in real time, but also leads to a new expression for the causal exchange-correlation kernel in terms of Berry curvature. Furthermore, I show that all the results that were previously derived from symmetries of the action functional remain valid in the present formulation. Finally, I develop a model functional theory which explicitly demonstrates the workings of the new formulation.Comment: 21 page

    Apollo-11 lunar sample information catalogue

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    The Apollo 11 mission is reviewed with emphasis on the collection of lunar samples, their geologic setting, early processing, and preliminary examination. The experience gained during five subsequent missions was applied to obtain physical-chemical data for each sample using photographic and binocular microscope techniques. Topics discussed include: binocular examination procedure; breccia clast dexrriptuons, thin section examinations procedure typical breccia in thin section, typical basalt in thin section, sample histories, and chemical and age data. An index to photographs is included

    1966 Beef Cattle Progress Report of Research Activities

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    Many beef cattle breeders in the United States and other countries are following the progress of the selection experiment at the Fort Robinson Beef Cattle Research Station, Crawford, Nebraska. Three lines of Hereford cattle from the same genetic foundation are under selection. Line 21 is selected for 200-day weight. Line 22 is selected for yearling weight. Line 23 is selected for an index combining yearling weight and a score for muscling and fat thickness. Each line is operated as a closed herd so it will be possible to determine how much improvement in economic traits can be made by selecting all replacement stock from within the same herd. Starting in 1966 there will be 150 calving cows in each line. Six herd sires are used each year. Two bulls and 25 heifers are selected to add to each line each year. Heifers are bred to calve first as two year olds. Cow numbers will be maintained at 150 by culling the oldest cows and those that fail to conceive or have a major physical unsoundness. Bulls are replaced after their third breeding season

    Beef Cattle Progress Report

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    Efficiency of sugar beet farming can be improved by feeding beet top silage to livestock. In two recent trials at the Scotts Bluff Experiment Station lambs fed unwilted beet top silage as the only roughage gained significantly faster than lambs fed corn silage. Amounts of concentrates were comparable (Nebraska Experiment Station Quarterly, Fall, 1962). This experiment compared the feeding value of a complete mixture of unwilted beet tops and concentrate added at the time of ensiling, with beet top silage and concentrate handled separately. A conventional corn silage and concentrate ration was used as a control. Results showed that a complete ration prepared by mixing unwilted beet tops and concentrates at the time of ensiling did not produce greater gains than a ration of unwilted beet top silage and concentrates fed separately

    Temperatures of dust and gas in S~140

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    In dense parts of interstellar clouds (> 10^5 cm^-3), dust & gas are expected to be in thermal equilibrium, being coupled via collisions. However, previous studies have shown that the temperatures of the dust & gas may remain decoupled even at higher densities. We study in detail the temperatures of dust & gas in the photon-dominated region S 140, especially around the deeply embedded infrared sources IRS 1-3 and at the ionization front. We derive the dust temperature and column density by combining Herschel PACS continuum observations with SOFIA observations at 37 μ\mum and SCUBA at 450 μ\mum. We model these observations using greybody fits and the DUSTY radiative transfer code. For the gas part we use RADEX to model the CO 1-0, CO 2-1, 13CO 1-0 and C18O 1-0 emission lines mapped with the IRAM-30m over a 4' field. Around IRS 1-3, we use HIFI observations of single-points and cuts in CO 9-8, 13CO 10-9 and C18O 9-8 to constrain the amount of warm gas, using the best fitting dust model derived with DUSTY as input to the non-local radiative transfer model RATRAN. We find that the gas temperature around the infrared sources varies between 35 and 55K and that the gas is systematically warmer than the dust by ~5-15K despite the high gas density. In addition we observe an increase of the gas temperature from 30-35K in the surrounding up to 40-45K towards the ionization front, most likely due to the UV radiation from the external star. Furthermore, detailed models of the temperature structure close to IRS 1 show that the gas is warmer and/or denser than what we model. Finally, modelling of the dust emission from the sub-mm peak SMM 1 constrains its luminosity to a few ~10^2 Lo. We conclude that the gas heating in the S 140 region is very efficient even at high densities, most likely due to the deep UV penetration from the embedded sources in a clumpy medium and/or oblique shocks.Comment: 15 pages, 23 figures, 4 tables, accepted for publication in A&

    Stress condensation in crushed elastic manifolds

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    We discuss an M-dimensional phantom elastic manifold of linear size L crushed into a small sphere of radius R << L in N-dimensional space. We investigate the low elastic energy states of 2-sheets (M=2) and 3-sheets (M=3) using analytic methods and lattice simulations. When N \geq 2M the curvature energy is uniformly distributed in the sheet and the strain energy is negligible. But when N=M+1 and M>1, both energies appear to be condensed into a network of narrow M-1 dimensional ridges. The ridges appear straight over distances comparable to the confining radius R.Comment: 4 pages, RevTeX + epsf, 4 figures, Submitted to Phys. Rev. Let

    Apollo 14 coarse fines (4-10 mm) sample location and classification

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    The 4 to 10 mm sieve fraction from the soil samples collected during the Apollo 14 Mission was identified and described. Examination and description of the fines were carried out in nitrogen-filled, stainless steel cabinets during a general examination of the Apollo 14 sample collection. Each particle was held between forceps, dusted in a jet of N2, and placed on a teflon-covered stage. They were examined with a binocular microscope, separated by lithology, and the lithologic types described. Weights of individual particles in the fraction ranged from about 0.10 to 0.50 gm, large enough in size for studies of age, chemistry, and petrology to be accomplished

    Limits on the Mass, Velocity and Orbit of PSR J1933−-6211

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    We present a high-precision timing analysis of PSR J1933−-6211, a millisecond pulsar (MSP) with a 3.5-ms spin period and a white dwarf (WD) companion, using data from the Parkes radio telescope. Since we have accurately measured the polarization properties of this pulsar we have applied the matrix template matching approach in which the times of arrival are measured using full polarimetric information. We achieved a weighted root-mean-square timing residuals (rms) of the timing residuals of 1.23 μs\rm \mu s, 15.5%\% improvement compared to the total intensity timing analysis. After studying the scintillation properties of this pulsar we put constraints on the inclination angle of the system. Based on these measurements and on χ2\chi^2 mapping we put a 2-σ\sigma upper limit on the companion mass (0.44 M⊙_\odot). Since this mass limit cannot reveal the nature of the companion we further investigate the possibility of the companion to be a He WD. Applying the orbital period-mass relation for such WDs, we conclude that the mass of a He WD companion would be about 0.26±\pm0.01 M⊙_\odot which, combined with the measured mass function and orbital inclination limits, would lead to a light pulsar mass ⩽\leqslant 1.0 M⊙_\odot. This result seems unlikely based on current neutron star formation models and we therefore conclude that PSR J1933−-6211 most likely has a CO WD companion, which allows for a solution with a more massive pulsar

    Rotating Boson Stars and Q-Balls

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    We consider axially symmetric, rotating boson stars. Their flat space limits represent spinning Q-balls. We discuss their properties and determine their domain of existence. Q-balls and boson stars are stationary solutions and exist only in a limited frequency range. The coupling to gravity gives rise to a spiral-like frequency dependence of the boson stars. We address the flat space limit and the limit of strong gravitational coupling. For comparison we also determine the properties of spherically symmetric Q-balls and boson stars.Comment: 22 pages, 18 figure
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