233 research outputs found

    Four-neutrino analysis of 1.5km-baseline reactor antineutrino oscillations

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    The masses of sterile neutrinos are not yet known, and depending on the orders of magnitudes, their existence may explain reactor anomalies or the spectral shape of reactor neutrino events at 1.5km-baseline detector. Here, we present four-neutrino analysis of the results announced by RENO and Daya Bay, which performed the definitive measurements of θ13\theta_{13} based on the disappearance of reactor antineutrinos at km-order baselines. Our results using 3+1 scheme include the exclusion curve of Δm412\Delta m^2_{41} vs. θ14\theta_{14} and the adjustment of θ13\theta_{13} due to correlation with θ14\theta_{14}. The value of θ13\theta_{13} obtained by RENO and Daya Bay with a three-neutrino oscillation analysis is included in the 1σ1\sigma interval of θ13\theta_{13} allowed by our four-neutrino analysis.Comment: 14 pages, 7 figures. arXiv admin note: text overlap with arXiv:1303.617

    Light sterile neutrino and leptogenesis

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    We studied models of leptogenesis where three right-handed Majorana neutrinos are involved and the minimal-extended seesaw mechanism including an additional singlet field produces four light neutrinos. This study shows that the type of mass ordering and heavy Majorana scales can be determined by inputting the simplest orthogonal matrix into the Casas-Ibarra(CI) representation of seesaw. The CP asymmetry produced from the decays of heavy neutrinos and the dilution mass are predicted in terms of the mass and mixing elements of the fourth neutrino. Upon the choice of CI matrix, the existence of a light sterile neutrino is required to explain the high-energy lepton asymmetry in light of phenomenological measurements. Although there are several free parameters attributable to an additional neutrino, the model can be in part constrained by low-energy experiments such as sterile neutrino searches and neutrinoless double-beta decays, as well as the observed baryon asymmetry in the universe.Comment: 23 pages, 7 figure

    Conflict between the identification of cosmic neutrino source and the sensitivity to mixing angles in neutrino telescope

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    Neutrino fluxes at telescopes depend on both initial fluxes out of astronomical bursts and flavor mixing during their travel to the earth. However, since the information on the initial composition requires better precision in mixing angles and vice versa, the neutrino detection at telescopes for itself cannot provide solutions to the both problems. Thus, a probability to be measured at long baseline oscillation is considered as a complement to the telescope, and problems like source identification and parameter degeneracy are examined under a few assumptions.Comment: 17 pages with 7 figures, published versio

    ON DEVELOPMENT OF STATISTICAL LEARNING METHODS IN PRECISION MEDICINE

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    Precision medicine is an area that seeks to maximize clinical effectiveness by assigning treatment regimes tailored to individuals. In this dissertation, we present three topics that advance the methods and applications in the field of precision medicine.The first topic introduces a novel methodology termed random forest informed tree-based learning to discover underlying patient characteristics associated with differential improvement in knee osteoarthritis (OA) symptoms and to identify the individualized treatment regime (ITR) among three available treatments. The proposed algorithm suggests decision rules that divide participants into subgroups based on their characteristics. In our analysis, the estimated treatment rule yielded greater improvements in OA symptoms that could ultimately guide patients toward suitable treatment strategies.In the second topic, we propose a doubly robust estimator for patient-specific utilities and ITRs based on the inverse reinforcement framework from Luckett et al. (2021). This framework optimizes patient-utility for two outcomes by leveraging experts’ decisions on observational data. The suggested doubly robust estimator guarantees consistency even whenincorrect outcome models or incorrect propensity score models are applied, alleviating the need for exact formulation of the outcome model and improving the previous estimator. We also present asymptotic distributions for the estimators of boundary and utility functions using the newly developed indexed argmax theorem, which can be used for deriving weak convergence ofM-estimators with multiple layers.Lastly, we suggest an estimator for utilities when there are more than two treatments. Specifically, we utilize stabilized direct learning to estimate ITRs. Subsequently, we apply the inverse reinforcement framework once again to obtain an estimator for a composite outcome and the balance of the two outcomes. Also, the proposed estimator for utilities considers theheterogeneity in the variance of patients, leveraging the benefits of stabilized direct learning.Doctor of Philosoph

    A complex-angle rotation and geometric complementarity in fermion mixing

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    The mixing among flavors in quarks or leptons in terms of a single rotation angle is defined such that three flavor eigenvectors are transformed into three mass eigenvectors by a single rotation about a common axis. We propose that a geometric complementarity condition exists between the complex angle of quarks and that of leptons in C2\mathbb{C}^2 space. The complementarity constraint has its rise in quark-lepton unification and is reduced to the correlation among θ12,θ23,θ13\theta_{12}, \theta_{23}, \theta_{13} and the CP phase δ\delta. The CP phase turns out to have a non-trivial dependence on all the other angles. We will show that further precise measurements in real angles can narrow down the allowed region of δ\delta. In comparison with other complementarity schemes, this geometric one can avoid the problem of the θ13\theta_{13} exception and can naturally keep the lepton basis being independent of quark basis.Comment: 9 pages, 4 figures, APPC 10 Pohan

    l-Menthol attenuates the magnitude of cold-induced vasodilation on the extremities of young females

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    Abstract Background Menthol chemically triggers cold-sensitive receptors in the skin without conductive skin cooling. We investigated the effects of menthol-induced activation of cutaneous cold receptors on the cold-induced vasodilation (CIVD) of the finger. We hypothesized that the menthol application would attenuate typical CIVD responses. Methods 1.5% l-menthol was fully applied over the left hand and forearm, and then, the middle finger of the left hand was immersed into 4 °C water for 30 min. A trial consisted of 10-min rest followed by 30-min immersion and 20-min recovery in 28 °C air temperature with 20% relative humidity. Another trial without the menthol application was carried out as a control. Seventeen females (24.2 ± 2.6 years in age, 160.5 ± 5.1 cm in height, and 51.2 ± 5.7 kg in body weight) participated in the two trials. Results The results showed that the maximum and average temperatures of the finger during the water immersion were lower in the menthol application when compared to control (P < 0.05), whereas no significant differences appeared in the onset time of CIVD, the frequency of CIVD, and minimum finger temperature. These results imply that stronger stimulation of cold receptors without additional conductive skin cooling did not attenuate the triggering of CIVD responses but intensified vasoconstriction after the first occurrence of CIVD. Conclusion It is suggested that substantial and conductive heat loss through the skin along with activation of cold receptors may be required to retain rewarming at a certain level
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