17,838 research outputs found

    Satisfiability of CTL* with constraints

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    We show that satisfiability for CTL* with equality-, order-, and modulo-constraints over Z is decidable. Previously, decidability was only known for certain fragments of CTL*, e.g., the existential and positive fragments and EF.Comment: To appear at Concur 201

    Comparison of Methods to Determine the Fluence of Monoenergetic Neutrons in the Energy Range from 30 keV to 14.8 MeV

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    The primary reference instruments for neutron fluence measurements used at the Physikalisch-Technische Bundesanstalt (PTB) are based on the primary standard for neutron measurements which is the differential neutron-proton scattering cross section. Such instruments require considerable effort for their operation and analysis. Therefore, routine measurements are carried out using a transfer instrument to facilitate the efficient provision of services to customers. A series of measurements was conducted to compare the transfer device to the primary reference instruments and ensure the traceability of neutron fluence measurements. This resulted in an improved characterization of the instrument and new analysis procedures

    Irreversibility and the arrow of time in a quenched quantum system

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    Irreversibility is one of the most intriguing concepts in physics. While microscopic physical laws are perfectly reversible, macroscopic average behavior has a preferred direction of time. According to the second law of thermodynamics, this arrow of time is associated with a positive mean entropy production. Using a nuclear magnetic resonance setup, we measure the nonequilibrium entropy produced in an isolated spin-1/2 system following fast quenches of an external magnetic field and experimentally demonstrate that it is equal to the entropic distance, expressed by the Kullback-Leibler divergence, between a microscopic process and its time-reverse. Our result addresses the concept of irreversibility from a microscopic quantum standpoint.Comment: 8 pages, 7 figures, RevTeX4-1; Accepted for publication Phys. Rev. Let

    CHEMICALLY MODIFIED PHOTOSYNTHETIC BACTERIAL REACTION CENTERS: CIRCULAR DICHROISM, RAMAN RESONANCE, LOW TEMPERATURE ABSORPTION, FLUORESCENCE AND ODMR SPECTRA AND POLYPEPTIDE COMPOSITION OF BOROHYDRIDE TREATED REACTION CENTERS FROM Rhodobacter sphaeroides R26

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    Reaction centers from Rhodobacter sphaeroides have been modified by treatment with sodium borohydride similar to the original procedure [Ditson et al., Biochim. Biophys. Acta 766, 623 (1984)], and investigated spectroscopically and by gel electrophoresis. (1) Low temperature (1.2 K) absorption, fluorescence, absorption- and fluorescence-detected ODMR, and microwave-induced singlet-triplet absorption difference spectra (MIA) suggest that the treatment produces a spectroscopically homogeneous preparation with one of the ‘additional’ bacteriochlorophylls being removed. The modification does not alter the zero field splitting parameters of the primary donor triplet (TP870). (2) From the circular dichroism and Raman resonance spectra in the1500–1800 cm-1 region, the removed pigment is assigned to BchlM, e.g. the "extra" Bchl on the "inactive" M-branch. (3) A strong coupling among all pigment molecules is deduced from the circular dichroism spectra, because pronounced band-shifts and/or intensity changes occur in the spectral components assigned to all pigments. This is supported by distinct differences among the MIA spectra of untreated and modified reaction centers, as well as by Raman resonance. (4) The modification is accompanied by partial proteolytic cleavage of the M-subunit. The preparation is thus spectroscopically homogeneous, but biochemically heterogenous

    Probing for evolutionary links between local ULIRGs and QSOs from NIR spectroscopy

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    We present a study of the dynamical evolution of Ultraluminous Infrared Galaxies (ULIRGs), merging galaxies of infrared luminosity >10^12 L_sun. During our Very Large Telescope large program, we have obtained ISAAC near-infrared, high-resolution spectra of 54 ULIRGs (at several merger phases) and 12 local Palomar-Green QSOs to investigate whether ULIRGs go through a QSO phase during their evolution. One possible evolutionary scenario is that after nuclear coalescence, the black hole radiates close to Eddington to produce QSO luminosities. The mean stellar velocity dispersion that we measure from our spectra is similar (~160 km/s) for 30 post-coalescence ULIRGs and 7 IR-bright QSOs. The black holes in both populations have masses of order 10^7-10^8 M_sun (calculated from the relation to the host dispersion) and accrete at rates >0.5 Eddington. Placing ULIRGs and IR-bright QSOs on the fundamental plane of early-type galaxies shows that they are located on a similar region (that of moderate-mass ellipticals), in contrast to giant ellipticals and radio-loud QSOs. While this preliminary comparison of the ULIRG and QSO host kinematical properties indicates that (some) ULIRGs may undergo a QSO phase in their evolutionary history before they settle down as ellipticals, further data on non-IR excess QSOs are necessary to test this scenario.Comment: To appear in the "QSO Host Galaxies: Evolution and Environment" conference proceedings; meeting held in Leiden, August 200

    Fate of recombinant DNA and Cry1Ab protein after ingestion and dispersal of genetically modified maize in comparison to rapeseed by fallow deer ( Dama dama )

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    The fate of recombinant DNA in fallow deer (Dama dama) was investigated by feeding a diet of isogenic or genetically modified (GM) maize expressing Cry1Ab protein against the European corn borer (Ostrinia nubilalis). To study the degradability of ingested DNA, polymerase chain reaction (PCR) assays were introduced to detect fragments of the endogenous, highly abundant chloroplast-specific rubisco gene, the maize-specific zein gene and the recombinant cry1Ab gene. PCR analysis revealed that small chloroplast- and maize-specific DNA fragments were detectable in contents of rumen, abomasums, jejunum, caecum and colon and occasionally in visceral tissues. In contrast, no fragments of the recombinant cry1Ab gene were detectable in gastrointestinal (GI) contents. The Cry1Ab protein was analysed using an enzyme-linked immunosorbent assay (ELISA) and immunoblotting technique. Neither ELISA nor immunoblotting yielded positive signals of immunoactive Cry1Ab protein in GI contents and tissues of fallow deer fed with GM maize. In conclusion, after uptake of GM maize, neither cry1Ab-specific gene fragments nor Cry1Ab protein were detected in the GI tract of fallow deer, indicating complete digestion of the GM maize. Additional investigations on the germination capacity of conventional rapeseed and maize seed after ingestion by fallow deer and faecal excretion (endozoochory) were performed to draw conclusions regarding a potential spreading of germinable GM crop seed by deer. Germination tests revealed that germinable rapeseed kernels were detectable in faeces; in contrast, no intact maize seeds were found in faece

    Self-report of Cognition and Objective Test Performance in Posttraumatic Headache

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74675/1/j.1526-4610.1996.3605300.x.pd
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