153 research outputs found

    Free initial wave packets and the long-time behavior of the survival and nonescape probabilities

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    The behavior of both the survival S(t) and nonescape P(t) probabilities at long times for the one-dimensional free particle system is shown to be closely connected to that of the initial wave packet at small momentum. We prove that both S(t) and P(t) asymptotically exhibit the same power-law decrease at long times, when the initial wave packet in momentum representation behaves as O(1) or O(k) at small momentum. On the other hand, if the integer m becomes greater than 1, S(t) and P(t) decrease in different power-laws at long times.Comment: 4 pages, 3 figures, Title and organization changed, however the results not changed, To appear in Phys. Rev.

    Electronic correlation in the infrared optical properties of the quasi two dimensional κ\kappa-type BEDT-TTF dimer system

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    The polarized optical reflectance spectra of the quasi two dimensional organic correlated electron system κ\kappa-(BEDT-TTF)2_{2}Cu[N(CN)2_{2}]YY, Y=Y = Br and Cl are measured in the infrared region. The former shows the superconductivity at TcT_{\rm c} \simeq 11.6 K and the latter does the antiferromagnetic insulator transition at TNT_{\rm N} \simeq 28 K. Both the specific molecular vibration mode ν3(ag)\nu_{3}(a_{g}) of the BEDT-TTF molecule and the optical conductivity hump in the mid-infrared region change correlatively at TT^{*} \simeq 38 K of κ\kappa-(BEDT-TTF)2_{2}Cu[N(CN)2_{2}]Br, although no indication of TT^{*} but the insulating behaviour below TinsT_{\rm ins} \simeq 50-60 K are found in κ\kappa-(BEDT-TTF)2_{2}Cu[N(CN)2_{2}]Cl. The results suggest that the electron-molecular vibration coupling on the ν3(ag)\nu_{3}(a_{g}) mode becomes weak due to the enhancement of the itinerant nature of the carriers on the dimer of the BEDT-TTF molecules below TT^{*}, while it does strong below TinsT_{\rm ins} because of the localized carriers on the dimer. These changes are in agreement with the reduction and the enhancement of the mid-infrared conductivity hump below TT^{*} and TinsT_{\rm ins}, respectively, which originates from the transitions between the upper and lower Mott-Hubbard bands. The present observations demonstrate that two different metallic states of κ\kappa-(BEDT-TTF)2_{2}Cu[N(CN)2_{2}]Br are regarded as {\it a correlated good metal} below TT^{*} including the superconducting state and {\it a half filling bad metal} above TT^{*}. In contrast the insulating state of κ\kappa-(BEDT-TTF)2_{2}Cu[N(CN)2_{2}]Cl below TinsT_{\rm ins} is the Mott insulator.Comment: 8 pages, 7 figure

    Discovery of widespread transcription initiation at microsatellites predictable by sequence-based deep neural network

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    Using the Cap Analysis of Gene Expression (CAGE) technology, the FANTOM5 consortium provided one of the most comprehensive maps of transcription start sites (TSSs) in several species. Strikingly, ~72% of them could not be assigned to a specific gene and initiate at unconventional regions, outside promoters or enhancers. Here, we probe these unassigned TSSs and show that, in all species studied, a significant fraction of CAGE peaks initiate at microsatellites, also called short tandem repeats (STRs). To confirm this transcription, we develop Cap Trap RNA-seq, a technology which combines cap trapping and long read MinION sequencing. We train sequence-based deep learning models able to predict CAGE signal at STRs with high accuracy. These models unveil the importance of STR surrounding sequences not only to distinguish STR classes, but also to predict the level of transcription initiation. Importantly, genetic variants linked to human diseases are preferentially found at STRs with high transcription initiation level, supporting the biological and clinical relevance of transcription initiation at STRs. Together, our results extend the repertoire of non-coding transcription associated with DNA tandem repeats and complexify STR polymorphism

    A study of the evolution of the representational capabilities of process modeling grammars

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    A plethora of process modeling techniques has been proposed over the years. One way of evaluating and comparing the scope and completeness of techniques is by way of representational analysis. The purpose of this paper is to examine how process modeling techniques have developed over the last four decades. The basis of the comparison is the Bunge-Wand-Weber representation model, a benchmark used for the analysis of grammars that purport to model the real world and the interactions within it. This paper presents a comparison of representational analyses of several popular process modeling techniques and has two main outcomes. First, it provides insights, within the boundaries of a representational analysis, into the extent to which process modeling techniques have developed over time. Second, the findings also indicate areas in which the underlying theory seems to be over-engineered or lacking in specialization

    Influence of Cranberry Proanthocyanidins on Formation of Biofilms by Streptococcus mutans on Saliva-Coated Apatitic Surface and on Dental Caries Development in vivo

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    Cranberry crude extracts, in various vehicles, have shown inhibitory effects on the formation of oral biofilms in vitro. The presence of proanthocyanidins (PAC) in cranberry extracts has been linked to biological activities against specific virulence attributes of Streptococcus mutans, e.g. the inhibition of glucosyltransferase (Gtf) activity. The aim of the present study was to determine the influence of a highly purified and chemically defined cranberry PAC fraction on S. mutans biofilm formation on saliva-coated hydroxyapatite surface, and on dental caries development in Sprague-Dawley rats. In addition, we examined the ability of specific PAC (ranging from low-molecular-weight monomers and dimers to high-molecular-weight oligomers/polymers) to inhibit GtfB activity and glycolytic pH drop by S. mutans cells, in an attempt to identify specific bioactive compounds. Topical applications (60-second exposure, twice daily) with PAC (1.5 mg/ml) during biofilm formation resulted in less biomass and fewer insoluble polysaccharides than the biofilms treated with vehicle control had (10% ethanol, v/v; p < 0.05). The incidence of smooth-surface caries in rats was significantly reduced by PAC treatment (twice daily), and resulted in less severe carious lesions compared to the vehicle control group (p < 0.05); the animals treated with PAC also showed significantly less caries severity on sulcal surfaces (p < 0.05). Furthermore, specific A-type PAC oligomers (dimers to dodecamers; 0.1 mg/ml) effectively diminished the synthesis of insoluble glucans by GtfB adsorbed on a saliva-coated hydroxyapatite surface, and also affected bacterial glycolysis. Our data show that cranberry PAC reduced the formation of biofilms by S. mutans in vitro and dental caries development in vivo, which may be attributed to the presence of specific bioactive A-type dimers and oligomers
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