11,715 research outputs found

    Time-dependent density functional theory on a lattice

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    A time-dependent density functional theory (TDDFT) for a quantum many-body system on a lattice is formulated rigorously. We prove the uniqueness of the density-to-potential mapping and demonstrate that a given density is vv-representable if the initial many-body state and the density satisfy certain well defined conditions. In particular, we show that for a system evolving from its ground state any density with a continuous second time derivative is vv-representable and therefore the lattice TDDFT is guaranteed to exist. The TDDFT existence and uniqueness theorem is valid for any connected lattice, independently of its size, geometry and/or spatial dimensionality. The general statements of the existence theorem are illustrated on a pedagogical exactly solvable example which displays all details and subtleties of the proof in a transparent form. In conclusion we briefly discuss remaining open problems and directions for a future research.Comment: 12 pages, 1 figur

    Boulder trains in western Massachusetts

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    Guidebook for field trips in western Massachusetts, northern Connecticut and adjacent areas of New York: 67th annual meeting October 10, 11, and 12, 1975: Trip C-

    Review Essays

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    Buxtonella Sulcata A Ciliate Associated with Ulcerative Colitis in a Cow and Prevalence of Infection in Nebraska Cattle

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    The ciliated protozoan, Buxtonella sulcata, was found in 28% of a sample of Iowa cattle in 1927, and in 32% of a sample of Louisiana cattle in 1930. As far as we can ascertain it has not been reported in American cattle since. During the summer of 1962, B. sulcata was found associated with ulcerative colitis in a cow from northeast Nebraska. This finding prompted incidence of infection in the region

    Satellite power system: Concept development and evaluation program. Volume 3: Power transmission and reception. Technical summary and assessment

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    Efforts in the DOE/NASA concept development and evaluation program are discussed for the solar power satellite power transmission and reception system. A technical summary is provided together with a summary of system assessment activities. System options and system definition drivers are described. Major system assessment activities were in support of the reference system definition, solid state system studies, critical technology supporting investigations, and various system and subsystem tradeoffs. These activities are described together with reference system updates and alternative concepts for each of the subsystem areas. Conclusions reached as a result of the numerous analytical and experimental evaluations are presented. Remaining issues for a possible follow-on program are identified

    Draft Genome Sequence of Frankia sp. Strain CcI6, a Salt-Tolerant Nitrogen-Fixing Actinobacterium Isolated from the Root Nodule of Casuarina cunninghamiana

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    Members of the actinomycete genus Frankia form a nitrogen-fixing symbiosis with 8 different families of actinorhizal plants. We report a 5.57-Mbp draft genome sequence for Frankia sp. strain CcI6, a salt-tolerant nitrogen-fixing actinobacterium isolated from root nodules of Casurina cunninghamiana grown in Egyptian soils

    Milli-second Oscillations in the Persistent and Bursting Flux of Aql X-1 During an Outburst

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    The Rossi X-Ray Timing Explorer observed the soft X-Ray transient Aql X-1 during its outburst in February and March 1997. We report the discovery of quasi-periodic oscillations (QPOs) in its persistent flux with frequencies in the range of 740 to 830 Hz, Q-value of over 100, and a fractional RMS amplitude of (6.8 +- 0.6)%, and nearly coherent oscillations (NCOs) during a Type-I burst with a frequency of 549 Hz. The frequency of the QPOs in the persistent flux is correlated with the mass accretion rate on time scale of hours, but not on time scale of days. This is most likely the manifestation in a single source of the kHz QPO puzzle observed among many sources, i.e., on the one hand, individual sources show a correlation between the QPO frequency and the inferred mass accretion rate, on the other hand, the dozen or so sources with luminosities spanning two decades have essentially the same QPO frequencies. We propose that this multi-valued QPO frequency and mass accretion rate correlation indicates the existence of many similar regimes of the accretion disk. These regimes, with a very similar energy spectrum and QPO frequency, are distinguished from each other by the mass accretion rate or the total X-ray flux. The NCOs during the burst can be made almost perfectly coherent by taking into account a large frequency derivative. This strongly suggests that this frequency is related to the neutron star spin frequency. The large frequency derivative is attributable to the expansion or contraction of the neutron star photosphere during the burst.Comment: 6 pages, LaTex (aas2pp4), Accepted for publication in ApJ Let

    Permanent Draft Genome Sequences for Two Variants of Frankia sp. Strain CpI1, the First Frankia Strain Isolated from Root Nodules of Comptonia peregrina

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    Frankia stains CpI1-S and CpI1-P are members of Frankia lineage Ia that are able to reinfect plants of the Betulaceae and Myricaceae families. Here, we report two 7.6-Mbp draft genome sequences with 6,396 and 6,373 candidate protein-coding genes for CpI1-S and CpI1-P, respectively

    Planning Activity Report for NDE of Adhesive Bonded Structures

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    Following a workshop held at the Rockwell International Science Center, Thousand Oaks, California in January, 1979, an ad hoc planning activity was undertaken to set forth a program plan to address the needs in NDE for adhesive bonded structures. The objectives of the planning activity were to develop a program rationale and strategy, determine the existence of reasonable approaches, and to propose a detailed plan of action for review at the annual DARPA/AF meeting in September, 1979. The plan encompasses the basic elements of an accept/reject methodology based on fracture mechanics, expected developments of valid flaw growth models, stress analysis, and non-destructive measurement techniques. A central issue is the prospect for determining a valid non-destructive measure of strength for the bonded joint as might be reflected in the tendency for preexistent flaws to propagate under environmental loads

    Modifying the Einstein Equations off the Constraint Hypersuface

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    A new technique is presented for modifying the Einstein evolution equations off the constraint hypersurface. With this approach the evolution equations for the constraints can be specified freely. The equations of motion for the gravitational field variables are modified by the addition of terms that are linear and nonlocal in the constraints. These terms are obtained from solutions of the linearized Einstein constraints.Comment: 4 pages, 1 figure, uses REVTe
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