326 research outputs found

    QCD sum rules for the anti-charmed pentaquark

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    We present a QCD sum rule analysis for the anti-charmed pentaquark state with and without strangeness. While the sum rules for most of the currents are either non-convergent or dominated by the DNDN continuum, the one for the non-strange pentaquark current composed of two diquarks and an antiquark, is convergent and has a structure consistent with a positive parity pentaquark state after subtracting out the DNDN continuum contribution. Arguments are presented on the similarity between the result of the present analysis and that based on the constituent quark models, which predict a more stable pentaquark states when the antiquark is heavy.Comment: 19 pages, 8 figures, REVTex, revised version,new figures added and references update

    Haptic Feedback Relocation from the Fingertips to the Wrist for Two-Finger Manipulation in Virtual Reality

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    Relocation of haptic feedback from the fingertips to the wrist has been considered as a way to enable haptic interaction with mixed reality virtual environments while leaving the fingers free for other tasks. We present a pair of wrist-worn tactile haptic devices and a virtual environment to study how various mappings between fingers and tactors affect task performance. The haptic feedback rendered to the wrist reflects the interaction forces occurring between a virtual object and virtual avatars controlled by the index finger and thumb. We performed a user study comparing four different finger-to-tactor haptic feedback mappings and one no-feedback condition as a control. We evaluated users' ability to perform a simple pick-and-place task via the metrics of task completion time, path length of the fingers and virtual cube, and magnitudes of normal and shear forces at the fingertips. We found that multiple mappings were effective, and there was a greater impact when visual cues were limited. We discuss the limitations of our approach and describe next steps toward multi-degree-of-freedom haptic rendering for wrist-worn devices to improve task performance in virtual environments.Comment: 6 pages, 9 figures, 1 table, submitted and accepted to the IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS) 2022 Conferenc

    CYTOGENETIC ASPECTS HIGHLIGHTED IN MERISTEMATIC TISSUES OF CUCUMBERS (CUCUMIS SATIVUS) UNDER ACTION OF COPPER SULPHATE

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    The frequent use of pesticides in agriculture, as well as alarming increase of pollution of the ecosystems, justify the assessment of the cytotoxicity of these polluting agents on plants. Copper sulphate is used for the control of downy mildew to vegetables, fruit trees and vines. From this point of view, it is very often used in cucumber crops to combat downy mildew produced by the fungus Pseudoperonospora cubensis. The purpose of research was to assess the influence of copper sulphate on cytological activity in radicular meristematic tissues to Cucumis sativus (cucumber), one of the most popular vegetables for its freshness. The study reveals the mitodepresive effect of copper sulphate as well as a direct correlation between its concentration and the frequency of cytogenetic changes (sticky chromosomes, vagrant chromosomes, micronucleus, C-mitosis) identified in the meristematic tissues of Cucumis sativus. This suggests caution in the excessive use of copper sulphate for plant protection and, in particular, strict adherence to treatment concentrations

    STUDIES ON SOME QUALITY COMPONENTS IN A LANDRACE COLLECTION OF CLIMBING BEANS (PHASEOLUS VULGARIS VAR. COMMUNIS)

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    The study aimed at evaluating a landraces collection of climbing beans regarding some characters that contribute to quality of grains or green pods. The biological material was formed of 56 landraces and 2 varieties of climbing beans from which the grains or green pods can be used in food. The landraces were collected from western and southwestern Romania. The experimentation was performed over three years in a collection-type experience, arranged in three repetitions. As elements of quality we determined: the percentage of husks from beans, boiling coefficient, the percentage of bean total protein, 1000 grain weight, the percentage of sugar in green pods. The experimental data were processed by analysis of variance and applying the t-test for determination of differences from the variety ‘Aurie de Bacau’ used as a control. The collection includes precious populations for all studied characters, but their number is reduced. For the percentage of grain husks and the protein content of grain, the most populations are below the control variety. For sugar percentage in green pod and the coefficient of boiling, the landraces are similar to control variety. In the collection, there are populations that can be processed by selection or can be used as parents in hybridization programs

    New-generation biocompatible Ti-based metallic glass ribbons for flexible implants

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    We introduce five new biocompatible Ti-based metallic glass (MG) compositions with different metalloid and soft metal content for a synergistic improvement in corrosion properties. Without any potentially harmful elements such as Cu, Ni or Be, these novel alloys can eliminate the risk of inflammatory reaction when utilized for permanent medical implants. Excluding Cu, Ni or Be, which are essential for Ti-based bulk MG production, on the other hand, confines the glass-forming ability of novel alloys to a moderate level. In this study, toxic-element free MG alloys with significant metalloid (Si–Ge–B, 15–18 at.%) and minor soft element (Sn, 2–5 at.%) additions are produced in ribbon form using conventional single-roller melt spinning technique. Their glass-forming abilities and their structural and thermal properties are comparatively investigated using X-ray diffraction (XRD), synchrotron XRD and differential scanning calorimetry. Their corrosion resistance is ascertained in a biological solution to analyze their biocorrosion properties and compare them with other Ti-based bulk MGs along with energy dispersive X-ray. Ti60Zr20Si8Ge7B3Sn2 and Ti50Zr30Si8Ge7B3Sn2 MG ribbons present a higher pitting potential and passivation domain compared with other Ti-based MG alloys tested in similar conditions. Human mesenchymal stem cell metabolic activity and cytocompatibility tests confirm their outstanding cytocompatibility, outperforming Ti-Al6-V4

    Boosting expensive synchronizing heuristics

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    For automata, synchronization, the problem of bringing an automaton to a particular state regardless of its initial state, is important. It has several applications in practice and is related to a fifty-year-old conjecture on the length of the shortest synchronizing word. Although using shorter words increases the effectiveness in practice, finding a shortest one (which is not necessarily unique) is NP-hard. For this reason, there exist various heuristics in the literature. However, high-quality heuristics such as SynchroP producing relatively shorter sequences are very expensive and can take hours when the automaton has tens of thousands of states. The SynchroP heuristic has been frequently used as a benchmark to evaluate the performance of the new heuristics. In this work, we first improve the runtime of SynchroP and its variants by using algorithmic techniques. We then focus on adapting SynchroP for many-core architectures, and overall, we obtain more than 1000× speedup on GPUs compared to naive sequential implementation that has been frequently used as a benchmark to evaluate new heuristics in the literature. We also propose two SynchroP variants and evaluate their performance

    Conceptfusion: A flexible scene classification framework

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    We introduce ConceptFusion, a method that aims high accuracy in categorizing large number of scenes, while keeping the model relatively simpler and efficient for scalability. The proposed method combines the advantages of both low-level representations and high-level semantic categories, and eliminates the distinctions between different levels through the definition of concepts. The proposed framework encodes the perspectives brought through different concepts by considering them in concept groups that are ensembled for the final decision. Experiments carried out on benchmark datasets show the effectiveness of incorporating concepts in different levels with different perspectives. © Springer International Publishing Switzerland 2015

    Soft Magnetic Properties and Electromagnetic Shielding Performance of Fe40Ni40B20 Microfibers

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    Fi(40)Ni(40)B(20) metallic glass is a key material among the many amorphous systems investigated thus far, owing to its high strength and appealing soft magnetic properties that make it suitable for use as transformer cores. In this study, Fi(40)Ni(40)B(20) microfibers are fabricated down to 5 mu m diameter. Three different melt-spinning wheel velocities: approximate to 51 m s(-1), approximate to 59 m s(-1), and approximate to 63 m s(-1) (MG1, MG2, MG3) are used. Their fully amorphous structure is confirmed using X-ray diffraction, and differential scanning calorimetry (DSC) traces reveal a larger relaxation profile for the higher-quenched microfiber. Vibrating sample magnetometer measurements showed a higher saturation magnetization of 136 emug(-1) for annealed metallic glass microfibers with a wheel velocity of 59.66 ms(-1). Cylindrical magnetic field shields are obtained by aligning and wrapping the fibers around a cast. The observed anisotropic static field shielding behavior is in accordance with the microfibers' anisotropic nature. Composite samples are also produced by embedding the microfibers in an epoxy matrix to investigate their electromagnetic properties at GHz frequencies. Inclusion of the microfibers increase the composite's attenuation constant by 20 to 25 times, making it an ideal candidate for applications in the communications frequency range
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