2,293 research outputs found

    Expanded Quantum Cryptographic Entangling Probe

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    The paper [Howard E. Brandt, "Quantum Cryptographic Entangling Probe," Phys. Rev. A 71, 042312 (2005)] is generalized to include the full range of error rates for the projectively measured quantum cryptographic entangling probe.Comment: 4 page

    DOT tomography of the solar atmosphere. IV. Magnetic patches in internetwork areas

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    We use G-band and Ca II H image sequences from the Dutch Open Telescope (DOT) to study magnetic elements that appear as bright points in internetwork parts of the quiet solar photosphere and chromosphere. We find that many of these bright points appear recurrently with varying intensity and horizontal motion within longer-lived magnetic patches. We develop an algorithm for detection of the patches and find that all patches identified last much longer than the granulation. The patches outline cell patterns on mesogranular scales, indicating that magnetic flux tubes are advected by granular flows to mesogranular boundaries. Statistical analysis of the emergence and disappearance of the patches points to an average patch lifetime as long as 530+-50 min (about nine hours), which suggests that the magnetic elements constituting strong internetwork fields are not generated by a local turbulent dynamo.Comment: 8 pages, 6 figure

    The Sloan Digital Sky Survey Quasar Catalog IV. Fifth Data Release

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    We present the fourth edition of the Sloan Digital Sky Survey (SDSS) Quasar Catalog. The catalog contains 77,429 objects; this is an increase of over 30,000 entries since the previous edition. The catalog consists of the objects in the SDSS Fifth Data Release that have luminosities larger than M_i = -22.0 (in a cosmology with H_0 = 70 km/s/Mpc, Omega_M = 0.3, and Omega_Lambda = 0.7) have at least one emission line with FWHM larger than 1000 km/s, or have interesting/complex absorption features, are fainter than i=15.0, and have highly reliable redshifts. The area covered by the catalog is 5740 sq. deg. The quasar redshifts range from 0.08 to 5.41, with a median value of 1.48; the catalog includes 891 quasars at redshifts greater than four, of which 36 are at redshifts greater than five. Approximately half of the catalog quasars have i < 19; nearly all have i < 21. For each object the catalog presents positions accurate to better than 0.2 arcsec. rms per coordinate, five-band (ugriz) CCD-based photometry with typical accuracy of 0.03 mag, and information on the morphology and selection method. The catalog also contains basic radio, near-infrared, and X-ray emission properties of the quasars, when available, from other large-area surveys. The calibrated digital spectra cover the wavelength region 3800--9200A at a spectral resolution of ~2000. The spectra can be retrieved from the public database using the information provided in the catalog. The average SDSS colors of quasars as a function of redshift, derived from the catalog entries, are presented in tabular form. Approximately 96% of the objects in the catalog were discovered by the SDSS.Comment: 37 pages, Accepted for publication in A

    Lymphovascular and perineural invasion as selection criteria for adjuvant therapy in intrahepatic cholangiocarcinoma: a multi-institution analysis

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    AbstractObjectivesCriteria for the selection of patients for adjuvant chemotherapy in intrahepatic cholangiocarcinoma (IHCC) are lacking. Some authors advocate treating patients with lymph node (LN) involvement; however, nodal assessment is often inadequate or not performed. This study aimed to identify surrogate criteria based on characteristics of the primary tumour.MethodsA total of 58 patients who underwent resection for IHCC between January 2000 and January 2010 at any of three institutions were identified. Primary outcome was overall survival (OS).ResultsMedian OS was 23.0months. Median tumour size was 6.5cm and the median number of lesions was one. Overall, 16% of patients had positive margins, 38% had perineural invasion (PNI), 40% had lymphovascular invasion (LVI) and 22% had LN involvement. A median of two LNs were removed and a median of zero were positive. Lymph nodes were not sampled in 34% of patients. Lymphovascular and perineural invasion were associated with reduced OS [9.6months vs. 32.7months (P= 0.020) and 10.7months vs. 32.7months (P= 0.008), respectively]. Lymph node involvement indicated a trend towards reduced OS (10.7months vs. 30.0months; P= 0.063). The presence of either LVI or PNI in node-negative patients was associated with a reduction in OS similar to that in node-positive patients (12.1months vs. 10.7months; P= 0.541). After accounting for adverse tumour factors, only LVI and PNI remained associated with decreased OS on multivariate analysis (hazard ratio4.07, 95% confidence interval 1.60–10.40; P= 0.003).ConclusionsLymphovascular and perineural invasion are separately associated with a reduction in OS similar to that in patients with LN-positive disease. As nodal dissection is often not performed and the number of nodes retrieved is frequently inadequate, these tumour-specific factors should be considered as criteria for selection for adjuvant chemotherapy

    Directly Imaging Rocky Planets from the Ground

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    Over the past three decades instruments on the ground and in space have discovered thousands of planets outside the solar system. These observations have given rise to an astonishingly detailed picture of the demographics of short-period planets, but are incomplete at longer periods where both the sensitivity of transit surveys and radial velocity signals plummet. Even more glaring is that the spectra of planets discovered with these indirect methods are either inaccessible (radial velocity detections) or only available for a small subclass of transiting planets with thick, clear atmospheres. Direct detection can be used to discover and characterize the atmospheres of planets at intermediate and wide separations, including non-transiting exoplanets. Today, a small number of exoplanets have been directly imaged, but they represent only a rare class of young, self-luminous super-Jovian-mass objects orbiting tens to hundreds of AU from their host stars. Atmospheric characterization of planets in the <5 AU regime, where radial velocity (RV) surveys have revealed an abundance of other worlds, is technically feasible with 30-m class apertures in combination with an advanced AO system, coronagraph, and suite of spectrometers and imagers. There is a vast range of unexplored science accessible through astrometry, photometry, and spectroscopy of rocky planets, ice giants, and gas giants. In this whitepaper we will focus on one of the most ambitious science goals --- detecting for the first time habitable-zone rocky (<1.6 R_Earth) exoplanets in reflected light around nearby M-dwarfsComment: 8 pages, 1 figure, Astro2020 Science White Pape
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