11,144 research outputs found

    Use of Polymer Casts or Metal Particle Infusion of Ducts to Study Antigen Uptake in the Guinea Pig Mammary Gland

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    Microcorrosion casts were made of the duct system of guinea pig mammary glands by intramammary infusion of Mercox® polyester resin following involution of the glands after the first lactation. The acinar configuration of the involuted gland was apparent on examination of the casts by scanning electron microscopy (SEM). Surface features, which were readily identified as those of imprints of duct al epithelium, were visible at higher magnifications. The morphology of these casts corresponded to the patterns observed by SEM of ethanol cryofractured specimens of mammary tissue. Cryofractured specimens of guinea pig mammary glands were also examined by SEM following intramammary infusion of tantalum. Tantalum particles were observed within the lumina of many ducts. Large phagocytic cells within the lumina were shown to contain tantalum by using back scatter imaging in conjunction with secondary imaging

    Lattice-Based zk-SNARKs from Square Span Programs

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    Zero-knowledge SNARKs (zk-SNARKs) are non-interactive proof systems with short (i.e., independent of the size of the witness) and efficiently verifiable proofs. They elegantly resolve the juxtaposition of individual privacy and public trust, by providing an efficient way of demonstrating knowledge of secret information without actually revealing it. To this day, zk-SNARKs are widely deployed all over the planet and are used to keep alive a system worth billion of euros, namely the cryptocurrency Zcash. However, all current SNARKs implementations rely on so-called pre-quantum assumptions and, for this reason, are not expected to withstand cryptanalitic efforts over the next few decades. In this work, we introduce a new zk-SNARK that can be instantiated from lattice-based assumptions, and which is thus believed to be post-quantum secure. We provide a generalization in the spirit of Gennaro et al. (Eurocrypt'13) to the SNARK of Danezis et al. (Asiacrypt'14) that is based on Square Span Programs (SSP) and relies on weaker computational assumptions. We focus on designated-verifier proofs and propose a protocol in which a proof consists of just 5 LWE encodings. We provide a concrete choice of parameters, showing that our construction is practically instantiable

    QCD-based description of one-particle inclusive B decays

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    We discuss one-particle inclusive B decays in the limit of heavy b and c quarks. Using the large-N_C limit we factorize the non-leptonic matrix elements, and we employ a short distance expansion. Modeling the remaining nonperturbative matrix elements we obtain predictions for various decay channels and compare them with existing data.Comment: LaTeX, 22 pages, 6 figures (eps); analytical and numerical results unchanged, misrepresentation of experimental data in Fig. 5 corrected, final published versio

    Analysis of hadronic invariant mass spectrum in inclusive charmless semileptonic B decays

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    We make an analysis of the hadronic invariant mass spectrum in inclusive charmless semileptonic B meson decays in a QCD-based approach. The decay width is studied as a function of the invariant mass cut. We examine their sensitivities to the parameters of the theory. The theoretical uncertainties in the determination of Vub|V_{ub}| from the hadronic invariant mass spectrum are investigated. A strategy for improving the theoretical accuracy in the value of Vub|V_{ub}| is described.Comment: 13 pages, 5 Postscript figure

    Detection of water absorption in the day side atmosphere of HD 189733 b using ground-based high-resolution spectroscopy at 3.2 microns

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    We report a 4.8 sigma detection of water absorption features in the day side spectrum of the hot Jupiter HD 189733 b. We used high-resolution (R~100,000) spectra taken at 3.2 microns with CRIRES on the VLT to trace the radial-velocity shift of the water features in the planet's day side atmosphere during 5 h of its 2.2 d orbit as it approached secondary eclipse. Despite considerable telluric contamination in this wavelength regime, we detect the signal within our uncertainties at the expected combination of systemic velocity (Vsys=-3 +5-6 km/s) and planet orbital velocity (Kp=154 +14-10 km/s), and determine a H2O line contrast ratio of (1.3+/-0.2)x10^-3 with respect to the stellar continuum. We find no evidence of significant absorption or emission from other carbon-bearing molecules, such as methane, although we do note a marginal increase in the significance of our detection to 5.1 sigma with the inclusion of carbon dioxide in our template spectrum. This result demonstrates that ground-based, high-resolution spectroscopy is suited to finding not just simple molecules like CO, but also to more complex molecules like H2O even in highly telluric contaminated regions of the Earth's transmission spectrum. It is a powerful tool that can be used for conducting an immediate census of the carbon- and oxygen-bearing molecules in the atmospheres of giant planets, and will potentially allow the formation and migration history of these planets to be constrained by the measurement of their atmospheric C/O ratios.Comment: 5 pages, 4 figures, accepted for publication in MNRAS Letter

    New Approach for Measuring Vub|V_{ub}| at Future BB-Factories

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    It is suggested that the measurements of hadronic invariant mass (mXm_X) distributons in the inclusive BXc(u)lνB \rightarrow X_{c(u)} l \nu decays can be useful in extracting the CKM matrix element Vub|V_{ub}|. We investigated hadronic invariant mass distributions within the various theoretical models of HQET, FAC and chiral lagrangian as well as ACCMM model. It is also emphasized that the mXm_X distribution even at the region mX>mDm_{X} > m_{D} in the inclusive bub\rightarrow u are effetive in selecting the events, experimentally viable at the future asymmetric BB factories, with better theoretical understandings.Comment: 11 pages not including 1 figur

    Identification of Neutral B Mesons Using Correlated Hadrons

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    The identification of the flavor of a neutral BB meson can make use of hadrons produced nearby in phase space. Examples include the decay of ``BB^{**}'' resonances or the production of hadrons as a result of the fragmentation process. Some aspects of this method are discussed, including time-dependent effects in neutral BB decays to flavor states, to eigenstates of CP and to other states, and the effects of possible coherence between B0B^0 and B0\overline{B}^0 in the initial state. We study the behavior of the leading hadrons in bb-quark jets and the expected properties of BB^{**} resonances. These are extrapolated from the corresponding DD^{**} resonances, of whose properties we suggest further studies.Comment: To be submitted to Phys. Rev. D. 26 pages, LaTeX, figures not included (available upon request). Technion-PH-93-32 / EFI 93-4

    Effects of Possible ΔB=ΔQ\Delta B =- \Delta Q Transitions in Neutral BB Meson Decays}

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    We explore the possibility that the existing data on like-sign dileptons at the Υ(4S)\Upsilon (4S) resonance consist of events arising from Bd0Bˉd0B_{d}^0 -\bar B_{d}^0 mixing and also from ΔB=ΔQ\Delta B = - \Delta Q transitions. The consequences of these nonstandard transitions for certain time-asymmetries which are likely to be measured at the BB factories are studied.Comment: {\LARGE \bf 10 pages, no figures, process using latex, TIFR/TH/93-5
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