180 research outputs found

    Attribute-Based Signatures for Circuits with Optimal Parameter Size from Standard Assumptions

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    Attribute-based signatures (ABS) allow users to simultaneously sign messages and prove their possession of some attributes while hiding the attributes and revealing only the fact that they satisfy a public policy. In this paper, we propose a generic construction of ABS for circuits of unbounded depth and size with optimal parameter size, meaning that the lengths of public parameters, keys, and signatures are all constant. Our generic construction can be instantiated from various standard assumptions including LWE or DLIN. Only previous ABS construction with optimal parameter size necessitates succinct non-interactive argument of knowledge, which can be only constructed from non-standard assumptions. Our generic construction is based on RAM delegations, which intuitively allows us to compress the evaluation of a circuit when inputs are public. In high level, we find a way to compress the computation of the policy circuit on input a user attribute to achieve overall parameter size, while hiding the user policy at the same time

    Chlamydial Infection-Dependent Synthesis of Sphingomyelin as a Novel Anti-Chlamydial Target of Ceramide Mimetic Compounds

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    The obligate intracellular bacterium Chlamydia trachomatis is the major causative agent of bacterial sexually transmitted diseases worldwide. In infected cells, the ceramide transport protein (CERT) is recruited to inclusions, where C. trachomatis replicates using host-synthesized ceramide. The ceramide is converted to sphingomyelin (SM) by a chlamydial infection-dependent SM synthesis (cidSM-synthesis) pathway, which occurs even in the absence of the SM synthases (SMS)-1 and -2 of host cells. The ceramide mimetic compound (1R,3S)-HPA-12 and the nonmimetic compound E16A, both of which are potent inhibitors of CERT, repressed the proliferation of C. trachomatis in HeLa cells. Unexpectedly, (1R,3R)-HPA-12, a ceramide mimetic compound that lacks CERT inhibitory activity, also exhibited potent anti-chlamydial activity. Using endogenous SMS-knockout mutant HeLa cells, we revealed that (1R,3R)-HPA-12 mildly inhibited cidSM-synthesis. In addition, LC-MS analysis revealed that (1R,3R)-HPA-12 is converted to a phosphocholine-conjugated metabolite in an infection-dependent manner. Imaging analysis with a fluorescent analog of ceramide suggested that cidSM-synthesis occurs in the bacterial bodies and/or inclusions. Collectively, these results suggested that (1R,3R)-HPA-12 exerts its anti-chlamydia activity not only as an inhibitor of cidSM-synthesis, but also via putative toxic effects of its phosphocholine adduct, which is most likely produced by the cidSM-synthesis route

    Spinal Deformity and the Musculoskeletal Cohort Study of the General Older Population

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    Article信州医学雑誌 69(3) : 111-120(2021)departmental bulletin pape

    Time-resolved photoelectron angular distributions from nonadiabatically aligned CO2 molecules with SX-FEL at SACLA

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    Weperformed time-resolved photoelectron spectroscopy of valence orbitals of alignedCO2 molecules using the femtosecond soft x-ray free-electron laser and the synchronized near-infrared laser. By properly ordering the individual single-shot ion images, we successfully obtained the photoelectron angular distributions (PADs) of theCO2 molecules aligned in the laboratory frame (LF). The simulations using the dipole matrix elements due to the time dependent density functional theory calculations well reproduce the experimental PADs by considering the axis distributions of the molecules. The simulations further suggest that, when the degrees of alignment can be increased up to \ue1 cos2 q\uf1 > 0.8, themolecular geometries during photochemical reactions can be extracted fromthe measured LFPADs once the accurate matrix elements are given by the calculations

    Verification of the Effectiveness of University-Sponsored Internships

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    本研究の目的は,大学生を対象とした大学主催インターンシップの効果を学問・就職活動の方法が異なる文系・理系学生を軸に検証することである。大学教育と職業の接続の一つとしてインターンシップが拡充されているが,職業に関連した分野を学んでいる理系学生を対象としたインターンシップと一部を除き必ずしも職業に直結しない文系学生を対象としたインターンシップの効果が異なる結果となるのではないかと考えた。検証の結果,効果のひとつである就業観の醸成では,文系学生は肯定的に捉えている一方,理系学生は,否定的と異なる結果であった。「獲得能力」については,文系学生は肯定的,理系学生は否定的な評価となった。全般的に文系学生は,比較的肯定的な評価しているが,理系学生,一部そうではない認識をしていることが確認された。departmental bulletin pape

    Fully gapped pairing state in spin-triplet superconductor UTe₂

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    The recently discovered superconductor UTe₂ is a promising candidate for spin-triplet superconductors, but the symmetry of the superconducting order parameter remains highly controversial. Here, we determine the superconducting gap structure by the thermal conductivity of ultraclean UTe₂ single crystals. We find that the a-axis thermal conductivity divided by temperature κ/T in zero-temperature limit is vanishingly small for both magnetic field H‖a and H‖c axes up to H/Hc₂ ∼ 0.2, demonstrating the absence of nodes around the a axis contrary to the previous belief. The present results, combined with the reduction of nuclear magnetic resonance Knight shift, indicate that the superconducting order parameter belongs to the isotropic Au representation with a fully gapped pairing state, analogous to the B phase of superfluid ³He. These findings reveal that UTe₂ is likely to be a long-sought three-dimensional strong topological superconductor, hosting helical Majorana surface states on any crystal plane

    Astrometric VLBI observations of H2_2O masers in an extreme OH/IR star candidate NSV17351

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    Results of astrometric very long baseline interferometry (VLBI) observations towards an extreme OH/IR star candidate NSV17351 are presented. We used the VERA (VLBI Exploration of Radio Astrometry) VLBI array to observe 22\,GHz H2_2O masers of NSV17351. We derived an annual parallax of 0.247±\pm0.035 mas which corresponds to a distance of 4.05±\pm0.59 kpc. By averaging the proper motions of 15 maser spots, we obtained the systemic proper motion of NSV17351 to be (μαcosδ,μδ\mu_{\alpha}\cos{\delta}, \mu_{\delta})avg^{\mathrm{avg}} == (-1.19 ±\pm 0.11, 1.30 ±\pm 0.19) mas\,yr1^{-1}. The maser spots spread out over a region of 20 mas ×\times 30 mas, which can be converted to a spatial distribution of \sim80 au ×\times \sim120 au at the source distance. Internal motions of the maser spots suggest an outward moving maser region with respect to the estimated position of the central star. From single dish monitoring of the H2_2O maser emission, we estimate the pulsation period of NSV17351 to be 1122±\pm24 days. This is the first report of the periodic activity of NSV17351, indicating that NSV17351 could have a mass of \sim4\,M_{\odot}. We confirmed that the time variation of H2_2O masers can be used as a period estimator of variable OH/IR stars. Furthermore, by inspecting dozens of double-peaked H2_2O maser spectra from the last 40 years, we detected a long-term acceleration in the radial velocity of the circumstellar matter to be 0.17±0.030.17\pm0.03 km\,s1^{-1}\,yr1^{-1} Finally, we determined the position and kinematics of NSV17351 in the Milky Way Galaxy and found that NSV17351 is located in an interarm region between the Outer and Perseus arms. We note that astrometric VLBI observations towards extreme OH/IR stars are useful samples for studies of the Galactic dynamics.Comment: Published in the Publications of the Astronomical Society of Japa
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