614 research outputs found

    Disorder effect on the localization/delocalization in incommensurate potential

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    The interplay between incommensurate (IC) and random potentials is studied in a two-dimensional symplectic model with the focus on localization/delocalization problem. With the IC potential only, there appear wavefunctions localized along the IC wavevector while extended perpendicular to it. Once the disorder potential is introduced, these turn into two-dimensional anisotropic metallic states beyond the scale of the elastic mean free path, and eventually becomes localized in both directions at a critical strength of the disorder. Implications of these results to the experimental observation of the IC-induced localization is discussed.Comment: 4 pages, 3 figures (7 files), RevTe

    New Supporting Evidence for the Overdensity of Galaxies around the Radio-Loud Quasar SDSS J0836+0054 at z =5.8

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    Recently, Zheng et al. (2005) found evidence for an overdensity of galaxies around a radio-loud quasar, SDSS J0836+0054, at z=5.8 (a five arcmin2^2 region). We have examined our deep optical imaging data (B, V, r', i', z', and NB816) taken with the Suprime-Cam on the Subaru Telescope. The NB816 narrow-band filter (lambda_c = 815 nm and Δλ=12\Delta\lambda = 12 nm) is suitable for searching for Lyα\alpha emitters at z≈5.7z\approx 5.7. We have found a new strong Lyα\alpha emitter at z≈5.7z \approx 5.7 close to object B identified by Zheng et al. Further, the non detection of the nine objects selected by Zheng et al. (2005) in our B, V, and r' images provides supporting evidence that they are high-z objects.Comment: 5 pages, 1 figure, accepted for PAS

    Strong Emission-Line Galaxies at Low Redshift in the Field around the Quasar SDSSp J104433.04-012502.2

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    We discuss observational properties of strong emission-line galaxies at low redshift found by our deep imaging survey for high-redshift Ly alpha emitters. In our surveys, we used the narrowband filter, NB816 (lambda_center=8150A with FWHM = 120A), and the intermediate-band filter, IA827 (lambda_center = 8270A with FWHM = 340A). In this survey, 62 NB816-excess (> 0.9 mag) and 21 IA827-excess (> 0.8 mag) objects were found. Among them, we found 20 NB816-excess and 4 IA827-excess Ly alpha emitter candidates. Therefore, it turns out that 42 NB816-excess and 17 IA827-excess objects are strong emission-line objects at lower redshift. Since 4 objects in the two low-z samples are common, the total number of strong low-z emitters is 55. Applying our photometric redshift technique, we identify 7 H alpha emitters at z~0.24, 20 H beta-[OIII] ones at z~0.65, and 11 [OII] ones at z~1.19. However, we cannot determine reliable photometric redshifts of the remaining 17 emitters. The distributions of their rest frame equivalent widths are consistently understood with recent studies of galaxy evolution from z~1 to z~0.Comment: 28 pages, 8 figures, PASJ, Vol. 58, No. 1, in pres

    A q-analog of the ADHMN construction and axisymmetric multi-instantons

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    In the preceding paper (Phys. Lett. B463 (1999) 257), the authors presented a q-analog of the ADHMN construction and obtained a family of anti-selfdual configurations with a parameter q for classical SU(2) Yang-Mills theory in four-dimensional Euclidean space. The family of solutions can be seen as a q-analog of the single BPS monopole preserving (anti-)selfduality. Further discussion is made on the relation to axisymmetric ansatz on anti-selfdual equation given by Witten in the late seventies. It is found that the q-exponential functions familiar in q-analysis appear as analytic functions categorizing the anti-selfdual configurations yielded by axisymmetric ansatz.Comment: 11pages, Latex2e, to appear in Journal of Physics A: Mathematical and General as a `Special Issue/Difference Equations

    Antifungal Activity of Endophytic Bacteria Associated with Sweet Sorghum (Sorghum bicolor)

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    The contribution of endophytic bacteria to the wellbeing of plants as biocontrol agents may be due to endophytic bacteria growing in the same niche as phytopathogens. This work was conducted to study the antagonistic activity of endophytic bacteria recovered from sweet sorghum against Sclerotium rolfsii, Fusarium solani, Fusarium oxysporum, Colletotrichum gloeosporioides in vitro and evaluate the mechanisms of these fungal inhibitions. We selected 78 endophytic bacteria from the stem and root of sweet sorghum plants. They were tested for antagonist activity by direct confrontation method. Antifungal compound production and lytic enzyme activity were examined to determine their mechanisms in inhibiting fungal pathogens. Antifungal compound production was checked by detecting the presence of NRPS and PKS genes. Lytic enzyme activity of the bacteria was evaluated by their ability to produce cellulase, chitinase, and protease. Selected bacteria were identified using molecular analysis based on the 16S rRNA gene. 14 out of the 78 tested isolates showed antagonistic activity and two were able to inhibit all four tested fungal strains. Four bacteria, designated as ACIL1, ACNM4, ACNM6, and ATNM4, produced natural products via NRPS pathway, but only one bacterial extract, designated as ACNM4, showed fungal inhibition. Ten isolates were able to produce hydrolytic enzymes. Endophytic bacteria identified as Burkholderia were revealed to have potential as a biocontrol agent

    Topological classification of black Hole: Generic Maxwell set and crease set of horizon

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    The crease set of an event horizon or a Cauchy horizon is an important object which determines qualitative properties of the horizon. In particular, it determines the possible topologies of the spatial sections of the horizon. By Fermat's principle in geometric optics, we relate the crease set and the Maxwell set of a smooth function in the context of singularity theory. We thereby give a classification of generic topological structure of the Maxwell sets and the generic topologies of the spatial section of the horizon.Comment: 22 pages, 6 figure

    Retrospective Analysis of Emergency Department Ultrasound for Acute Appendicitis

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    OBJECTIVES: To determine whether emergency physicians (EPs) who have skills in the other applications of ultrasound can apply these in appendicitis diagnosis. METHODS: EPs did not have focused training in bedside ultrasound for appendicitis. We identified patients receiving an ED bedside ultrasound evaluation for appendicitis from our ultrasound log. Criterion reference was radiology ultrasound (RUS), CT scan, or pathology report. RESULTS: We performed 155 ED ultrasounds for appendicitis. There were 27/155 cases where the ED ultrasound was true positive and agreed with pathology (sensitivity = 39%, 95% CI 28 – 52%). In 42/155 (27%) the ED ultrasound was non-diagnostic (false negative) with pathology positive. In 77 cases the ED ultrasound was true negative with non-visualization of the appendix in concert with non-visualization by RUS or CT scan (specificity = 90%, 95% CI 81-95%). In nine cases (6%), ED ultrasound was falsely positive, compared to CT scan with surgical consult. CONCLUSION: ED ultrasound by EPs prior to focused appendicitis ultrasound training is insufficiently accurate

    Diffuse Hard X-ray Sources Discovered with the ASCA Galactic Plane Survey

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    We found diffuse hard X-ray sources, G11.0+0.0, G25.5+0.0, and G26.6-0.1 in the ASCA Galactic plane survey data. The X-ray spectra are featureless with no emission line, and are fitted with both models of a thin thermal plasma in non-equilibrium ionization and a power-law function. The source distances are estimated to be 1-8 kpc, using the best-fit NH values on the assumption that the mean density in the line of sight is 1 H cm^-3. The source sizes and luminosities are then 4.5-27 pc and (0.8-23)x10^33 ergs/s. Although the source sizes are typical to supernova remnants (SNR) with young to intermediate ages, the X-ray luminosity, plasma temperature, and weak emission lines in the spectra are all unusual. This suggests that these objects are either shell-like SNRs dominated by X-ray synchrotron emission, like SN 1006, or, alternatively, plerionic SNRs. The total number of these classes of SNRs in our Galaxy is also estimated.Comment: 17 pages, 9 figures; to appear in Ap

    Effective mass staircase and the Fermi liquid parameters for the fractional quantum Hall composite fermions

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    Effective mass of the composite fermion in the fractional quantum Hall system, which is of purely interaction originated, is shown, from a numerical study, to exhibit a curious nonmonotonic behavior with a staircase correlated with the number (=2,4,...) of attached flux quanta. This is surprising since the usual composite-fermion picture predicts a smooth behavior. On top of that, significant interactions are shown to exist between composite fermions, where the excitation spectrum is accurately reproduced in terms of Landau's Fermi liquid picture with negative (i.e., Hund's type) orbital and spin exchange interactions.Comment: 4 pages, 3 figures, REVTe
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