245 research outputs found

    Simplified numerical form of universal finite type invariant of Gauss words

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    In the present paper, we study the finite type invariants of Gauss words. In the Polyak algebra techniques, we reduce the determination of the group structure to transformation of a matrix into its Smith normal form and we give the simplified form of a universal finite type invariant by means of the isomorphism of this transformation. The advantage of this process is that we can implement it as a computer program. We obtain the universal finite type invariant of degree 4, 5, and 6 explicitly. Moreover, as an application, we give the complete classification of Gauss words of rank 4 and the partial classification of Gauss words of rank 5 where the distinction of only one pair remains.Comment: 12 pages, 3 table

    Flow dynamics and structure of solid pellets along the channel of a single screw extruder

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    Plasticating single screw extrusion involves the progressive compaction and heating of loose solid pellets that eventually melt, form a relatively homogenous stream and are subsequently pumped through a shaping tool. Traditional analyses of the solids conveying stage assume the sliding of an elastic solid plug due to differential wall friction coefficients. However, not only the corresponding predictions may fail considerably, but it is also well known that, at least in the initial screw turns, pellets are far from compact. This work follows previous efforts to model the flow of solids in the hopper and initial screw turns using the Discrete Element Method (DEM). The model considers the development of normal and tangential forces resulting from the inelastic collisions between the pellets and between them and the neighbouring metallic surfaces. As an example of the capability of the model to capture detailed features of granular flow, the effect of pellet size on flow is discussed.Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BPD/39381/2007

    Temporal-offset dual-comb vibrometer with picometer axial precision

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    We demonstrate a dual-comb vibrometer where the pulses of one frequency-comb are split into pulse pairs. We introduce a delay between the two pulses of each pulse pair in front of the sample, and after the corresponding two consecutive reflections at the vibrating sample surface, the initially introduced delay is cancelled by a modified Sagnac geometry. The remaining phase difference between the two pulses corresponds to the change in the axial position of the surface during the two consecutive reflections. The Sagnac geometry reduces the effect of phase jitter since both pulses propagate through nearly the same optical path (in opposite directions), and spurious signals are eliminated by time gating. We determine the amplitude of a surface vibration on a surface-acoustic-wave device with an axial precision of 4 pm. This technique enables highly accurate determination of extremely small displacements.Comment: 22 pages, 5 figure

    Strange filamentary structures ("fireballs") around a merger galaxy in the Coma cluster of galaxies

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    We found an unusual complex of narrow blue filaments, bright blue knots, and H-alpha emitting filaments and clouds, which morphologically resembled a complex of ``fireballs,'' extending up to 80 kpc south from an E+A galaxy RB199 in the Coma cluster. The galaxy has a highly disturbed morphology indicative of a galaxy--galaxy merger remnant. The narrow blue filaments extend in straight shapes toward the south from the galaxy, and several bright blue knots are located at the southern ends of the filaments. The Rc band absolute magnitudes, half light radii and estimated masses of the bright knots are -12 - -13 mag, 200 - 300 pc and 10^6-7 Msolar, respectively. Long, narrow H-alpha emitting filaments are connected at the south edge of the knots. The average color of the fireballs is B - Rc = 0.5, which is bluer than RB199 (B - R = 0.99), suggesting that most of the stars in the fireballs were formed within several times 10^8 yr. The narrow blue filaments exhibit almost no H-alpha emission. Strong H-alpha and UV emission appear in the bright knots. These characteristics indicate that star formation recently ceased in the blue filaments and now continues in the bright knots. The gas stripped by some mechanism from the disk of RB199 may be traveling in the intergalactic space, forming stars left along its trajectory. The most plausible fireball formation mechanism is ram pressure stripping by high-speed collision between the galaxy and the hot intra-cluster medium. The fireballs may be a snapshot of diffuse intra-cluster population formation, or halo star population formation in a cluster galaxy.Comment: 13 pages, 14 figures, submitted to Ap

    Modelling pellet flow in single extrusion with DEM

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    Plasticating single-screw extrusion involves the continuous conversion of loose solid pellets into a pressurized homogeneous melt that is pumped through a shaping tool. Traditional analyses of the solids conveying stage assume the movement of an elastic solid plug at a fixed speed. However, not only the corresponding predictions fail considerably, but it is also well known that, at least in the initial screw turns, the flow of loose individual pellets takes place. This study follows previous efforts to predict the characteristics of such a flow using the discrete element method. The model considers the development of normal and tangential forces resulting from the inelastic collisions between the pellets and between them and the neighbouring metallic surfaces. The algorithm proposed here is shown to be capable of capturing detailed features of the granular flow. The predictions of velocities in the cross- and down-channel directions and of the coordination number are in good agreement with equivalent reported results. The effect of pellet size on the flow features is also discussed

    Growth, strain, and spin-orbit torques in epitaxial Ni-Mn-Sb films sputtered on GaAs

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    We report current-induced spin torques in epitaxial NiMnSb films on a commercially available epiready GaAs substrate. The NiMnSb was grown by cosputtering from three targets using optimized parameters. The films were processed into microscale bars to perform current-induced spin-torque measurements. Magnetic dynamics were excited by microwave currents, and electric voltages along the bars were measured to analyze the symmetry of the current-induced torques. We found that the extracted symmetry of the spin torques matches those expected from spin-orbit interaction in a tetragonally distorted half-Heusler crystal. Both fieldlike and dampinglike torques are observed in all the samples characterized, and the efficiency of the current-induced torques is comparable to that of ferromagnetic metal/heavy-metal bilayers

    The Hyper Suprime-Cam Software Pipeline

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    In this paper, we describe the optical imaging data processing pipeline developed for the Subaru Telescope's Hyper Suprime-Cam (HSC) instrument. The HSC Pipeline builds on the prototype pipeline being developed by the Large Synoptic Survey Telescope's Data Management system, adding customizations for HSC, large-scale processing capabilities, and novel algorithms that have since been reincorporated into the LSST codebase. While designed primarily to reduce HSC Subaru Strategic Program (SSP) data, it is also the recommended pipeline for reducing general-observer HSC data. The HSC pipeline includes high level processing steps that generate coadded images and science-ready catalogs as well as low-level detrending and image characterizations.Comment: 39 pages, 21 figures, 2 tables. Submitted to Publications of the Astronomical Society of Japa

    Imiquimod for Cervical and Vaginal Intraepithelial Neoplasia: A Systematic Review and Meta-analysis.

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    OBJECTIVE To evaluate the treatment efficacy and the risk of adverse events of imiquimod for cervical intraepithelial neoplasia (CIN) and vaginal intraepithelial neoplasia (VAIN), compared with placebo or no intervention. DATA SOURCES We searched Cochrane, PubMed, ISRCTN registry, ClinicalTrials.gov, and the World Health Organization International Clinical Trials Registry Platform up to November 23, 2022. METHODS OF STUDY SELECTION We included randomized controlled trials and prospective nonrandomized studies with control arms that investigated the efficacy of imiquimod for histologically confirmed CIN or VAIN. The primary outcomes were histologic regression of the disease (primary efficacy outcome) and treatment discontinuation due to side effects (primary safety outcome). We estimated pooled odds ratios (ORs) of imiquimod, compared with placebo or no intervention. We also conducted a meta-analysis of the proportions of patients with adverse events in the imiquimod arms. TABULATION, INTEGRATION, AND RESULTS Four studies contributed to the pooled OR for the primary efficacy outcome. An additional four studies were available for meta-analyses of proportions in the imiquimod arm. Imiquimod was associated with increased probability of regression (pooled OR 4.05, 95% CI 2.08-7.89). Pooled OR for CIN in the three studies was 4.27 (95% CI 2.11-8.66); results of one study were available for VAIN (OR, 2.67, 95% CI 0.36-19.71). Pooled probability for primary safety outcome in the imiquimod arm was 0.07 (95% CI 0.03-0.14). The pooled probabilities (95% CI) of secondary outcomes were 0.51 (0.20-0.81) for fever, 0.53 (0.31-0.73) for arthralgia or myalgia, 0.31 (0.18-0.47) for abdominal pain, 0.28 (0.09-0.61) for abnormal vaginal discharge or genital bleeding, 0.48 (0.16-0.82) for vulvovaginal pain, and 0.02 (0.01-0.06) for vaginal ulceration. CONCLUSION Imiquimod was found to be effective for CIN, whereas data on VAIN were limited. Although local and systemic complications are common, treatment discontinuation is infrequent. Thus, imiquimod is potentially an alternative therapy to surgery for CIN. SYSTEMATIC REVIEW REGISTRATION PROSPERO, CRD42022377982

    Development and operational experience of magnetic horn system for T2K experiment

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    A magnetic horn system to be operated at a pulsed current of 320 kA and to survive high-power proton beam operation at 750 kW was developed for the T2K experiment. The first set of T2K magnetic horns was operated for over 12 million pulses during the four years of operation from 2010 to 2013, under a maximum beam power of 230 kW, and 6.63×10206.63\times10^{20} protons were exposed to the production target. No significant damage was observed throughout this period. This successful operation of the T2K magnetic horns led to the discovery of the νμ→νe\nu_{\mu}\rightarrow\nu_e oscillation phenomenon in 2013 by the T2K experiment. In this paper, details of the design, construction, and operation experience of the T2K magnetic horns are described.Comment: 22 pages, 40 figures, also submitted to Nuclear Instrument and Methods in Physics Research,

    Radiation resistance of praseodymium-doped aluminum lithium fluorophosphate scintillator glasses for laser fusion experiments

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    We report the gamma (γ)-ray radiation resistance of praseodymium (Pr3+)-doped aluminum lithium fluorophosphate scintillator glasses. For its assessment as a scintillator material for laser fusion experiments, a 20Al(PO3)3-80LiF-PrF3 (Pr3+-doped APLF) glass was irradiated with γ-rays from a cobalt-60 (60Co) source resulting in an absorbed dose of 5.2 kGy. Although γ-ray-irradiation results in increased absorption due to phosphorus-oxygen hole centers (POHCs) and PO32− electron centers (PO3 ECs), these radiation-induced defects do not modify the glass emission as both non-irradiated and γ-ray-irradiated glasses exhibit similar emission spectra and decay times under optical and X-ray excitation. The emission peaks observed also correspond to the different interconfigurational 4f5d → 4f2 and intraconfigurational 4f2 transitions of Pr3+ ions which are neither oxidized nor reduced by irradiation. Our results show that Pr3+-doped APLF glass still maintains its characteristic fast decay time and that γ-ray irradiation does not affect the glass scintillation mechanisms.Shinohara K., Empizo M.J.F., Cadatal-Raduban M., et al. Radiation resistance of praseodymium-doped aluminum lithium fluorophosphate scintillator glasses for laser fusion experiments. Japanese Journal of Applied Physics 62, 010613 (2023); https://doi.org/10.35848/1347-4065/aca0d4
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