38 research outputs found

    Threshold of Primordial Black Hole Formation in Nonspherical Collapse

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    We perform (3+1)-dimensional simulations of primordial black hole (PBH) formation starting from the spheroidal super-horizon perturbations. We investigate how the ellipticity (prolateness or oblateness) affects the threshold of PBH formation in terms of the peak amplitude of curvature perturbation. We find that, in the case of the radiation-dominated universe, the effect of ellipticity on the threshold is negligibly small for large amplitude of perturbations expected for PBH formation.Comment: Two-column, 5 pages, 8 figure

    Dark matter physics, flavor physics and LHC constraints in the dark matter model with a bottom partner

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    In the scenario that a dark matter (DM) is a weakly interacting massive particle, there are many possibilities of the interactions with the Standard Model (SM) particles to achieve the relic density of DM. In this paper, we consider one simple DM model where the DM candidate is a complex scalar and interacts with the SM particles via exchange of the Higgs particle and an extra quark, named bottom partner. The extra quark carries the same quantum number as the right-handed down-type quarks and has Yukawa couplings with the DM candidate and the right-handed down-type quarks. The Yukawa interactions are not only relevant to the thermal relic density of the DM, but also contribute to the flavor physics, such as the ΔF=2\Delta F=2 processes. In addition, the flavor alignment of the Yukawa couplings is related to the decay modes of the extra quark. Then, we can find the explicit correlations among the physical observables in DM physics, flavor physics and the signals at the LHC. Based on the numerical analyses of the thermal relic density, the direct detection of the DM and the current LHC bounds using the latest results, we survey our predictions for the ΔF=2\Delta F=2 processes. We investigate the perturbative bound on the Yukawa coupling, as well. Study of a fermionic DM model with extra scalar quarks is also given for comparison.Comment: 18 pages, 8 figures, 2 tables; some typos corrected, version published in JHE

    Dynamical Aspects of Large N Reduced Models

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    We study the large N reduced model of D-dimensional Yang-Mills theory with special attention to dynamical aspects related to the eigenvalues of the N by N matrices, which correspond to the space-time coordinates in the IIB matrix model. We first put an upper bound on the extent of space time by perturbative arguments. We perform a Monte Carlo simulation and show that the upper bound is actually saturated. The relation of our result to the SSB of the U(1)^D symmetry in the Eguchi-Kawai model is clarified. We define a quantity which represents the uncertainty of the space-time coordinates and show that it is of the same order as the extent of space time, which means that a classical space-time picture is maximally broken. We develop a 1/D expansion, which enables us to calculate correlation functions of the model analytically. The absence of an SSB of the Lorentz invariance is shown by the Monte Carlo simulation as well as by the 1/D expansion.Comment: 41 pages, LaTeX, 15 eps figures; comments added for the well-definedness of the models and for a related referenc

    Local Control of Squamous Cell Carcinoma of the Cervix Treated with CT-based Three-dimensional Image-Guided Brachytherapy with or without Central Shielding

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    The purposes of this retrospective study were to analyze local control of squamous cell carcinoma of the cervix treated with computed tomography (CT)-based image-guided brachytherapy (IGBT), as well as the factors affecting local control. A total of 39 patients were analyzed. The prescribed dose to the pelvis was 45-50 Gy with or without central shielding (CS). IGBT was delivered in 1-5 fractions. The total dose for high-risk clinical target volume (HR-CTV) was calculated as the biologically equivalent dose in 2-Gy fractions. The median follow-up period was 29.3 months. The 2-year overall survival and local control rates were 97% and 91%, respectively. In univariate analysis, the dose covering 90% of the HR-CTV (D90) and tumor size were found to be significant factors for local control. The cutoff values of tumor size and D90 for local control were 4.3 cm (area under the curve [AUC] 0.75) and 67.7 Gy (AUC 0.84) in the CS group and 5.3 cm (AUC 0.75) and 73.7 Gy (AUC 0.78) in the group without CS, respectively. However, though the local control of CT-based IGBT was favorable, the results suggested that the dose required for tumor control may differ depending on the presence of CS

    Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

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    A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

    Association between exposure to secondhand aerosol from heated tobacco products and respiratory symptoms among current non-smokers in Japan: a cross-sectional study

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    Objectives To investigate the association between secondhand-aerosol exposure from heated tobacco products (HTPs) and respiratory symptoms among current non-smokers.Design Cross-sectional study.Setting Internet survey conducted between 8 and 26 February 2021 in Japan.Participants Non-smoking respondents at the survey aged 15–80 years.Exposure Self-reported secondhand-aerosol exposure.Primary and secondary outcomes We defined asthma/asthma-like symptoms as a primary outcome and persistent cough as a secondary outcome. We examined the association between secondhand-aerosol exposure from HTPs and respiratory symptoms (asthma attacks/asthma-like symptoms and persistent cough). The prevalence ratio (PR) and 95% CI were calculated by using weighted, multivariable ‘modified’ Poisson regression models.Results Of the 18 839 current non-smokers, 9.8% (95% CI 8.2% to 11.7%) and 16.7% (95% CI 14.8% to 18.9%) of those who were exposed to secondhand aerosols reported asthma attacks/asthma-like symptoms and persistent cough, whereas 4.5% (95% CI 3.9% to 5.2%) and 9.6% (95% CI 8.4% to 11.0%) of those who were not, respectively. Secondhand-aerosol exposure was associated with respiratory symptoms (asthma attacks/asthma-like symptoms: PR 1.49, 95% CI 1.21 to 1.85; persistent cough: PR 1.44, 95% CI 1.21 to 1.72) after adjusting for covariates.Conclusion Secondhand-aerosol exposure from HTPs was associated with both asthma attacks/asthma-like symptoms and persistent cough. These results provide policymakers with meaningful information in the regulation of HTP use for the protection of current non-smokers

    Multiple neck operations in a patient with severe motor tics because of Tourette’s syndrome: a case report

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    Abstract Introduction In patients with Tourette’s syndrome who have severe motor tics, involuntary neck movements can enhance degenerative changes in the cervical spine, occasionally causing myelopathy. There have been a limited number of reports on surgical treatment for cervical myelopathy caused by Tourette’s syndrome, and a consensus for surgical treatment has not been fully established. To the best of our knowledge, this is the first report that describes a case of cervical myelopathy in a patient with Tourette’s syndrome with severe motor tics who has undergone multiple surgeries of the cervical spine. Case presentation A 44-year-old Asian man with severe motor tics due to Tourette’s syndrome presented with cervical myelopathy. Previously, he had undergone an anterior discectomy and spinal fusion with ceramics at the C3-C4 and C5-C6 levels, but required further surgery because of displacement of the ceramics. After the second operation, he developed compression myelopathy at the sandwiched (C4-C5) disc level, and had to undergo a C4-C5 anterior discectomy and spinal fusion, which was unsuccessful. As a salvage operation, we performed a C3-C7 decompression and spinal fusion from both the anterior and posterior approaches. By thorough postoperative external immobilization of his neck, our patient’s spinal fusion was successful and his neurological improvements were maintained for more than 10 years. Conclusions Patients with Tourette’s syndrome with cervical myelopathy are at risk of having multiple neck operations to correct their symptoms. Postoperative immobilization and the correct selection of surgical procedure are quite important for successful spinal fusion and for avoiding complications at adjacent levels in these patients.</p
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