168 research outputs found

    Measurements of neutrino oscillation parameters from the T2K experiment using 3.6×10213.6\times10^{21} protons on target

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    International audienceThe T2K experiment presents new measurements of neutrino oscillation parameters using 19.7(16.3)×102019.7(16.3)\times10^{20} protons on target (POT) in (anti-)neutrino mode at the far detector (FD). Compared to the previous analysis, an additional 4.7×10204.7\times10^{20} POT neutrino data was collected at the FD. Significant improvements were made to the analysis methodology, with the near-detector analysis introducing new selections and using more than double the data. Additionally, this is the first T2K oscillation analysis to use NA61/SHINE data on a replica of the T2K target to tune the neutrino flux model, and the neutrino interaction model was improved to include new nuclear effects and calculations. Frequentist and Bayesian analyses are presented, including results on sin2θ13\sin^2\theta_{13} and the impact of priors on the δCP\delta_\mathrm{CP} measurement. Both analyses prefer the normal mass ordering and upper octant of sin2θ23\sin^2\theta_{23} with a nearly maximally CP-violating phase. Assuming the normal ordering and using the constraint on sin2θ13\sin^2\theta_{13} from reactors, sin2θ23=0.5610.032+0.021\sin^2\theta_{23}=0.561^{+0.021}_{-0.032} using Feldman--Cousins corrected intervals, and Δm322=2.4940.058+0.041×103 eV2\Delta{}m^2_{32}=2.494_{-0.058}^{+0.041}\times10^{-3}~\mathrm{eV^2} using constant Δχ2\Delta\chi^{2} intervals. The CP-violating phase is constrained to δCP=1.970.70+0.97\delta_\mathrm{CP}=-1.97_{-0.70}^{+0.97} using Feldman--Cousins corrected intervals, and δCP=0,π\delta_\mathrm{CP}=0,\pi is excluded at more than 90% confidence level. A Jarlskog invariant of zero is excluded at more than 2σ2\sigma credible level using a flat prior in δCP\delta_\mathrm{CP}, and just below 2σ2\sigma using a flat prior in sinδCP\sin\delta_\mathrm{CP}. When the external constraint on sin2θ13\sin^2\theta_{13} is removed, sin2θ13=28.06.5+2.8×103\sin^2\theta_{13}=28.0^{+2.8}_{-6.5}\times10^{-3}, in agreement with measurements from reactor experiments. These results are consistent with previous T2K analyses

    Search for transient optical counterparts to high-energy IceCube neutrinos with Pan-STARRS1

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    In order to identify the sources of the observed diffuse high-energy neutrino flux, it is crucial to discover their electromagnetic counterparts. To increase the sensitivity of detecting counterparts of transient or variable sources by telescopes with a limited field of view, IceCube began releasing alerts for single high-energy (E-v > 60 TeV) neutrino detections with sky localisation regions of order 1 degrees radius in 2016. We used Pan-STARRS1 to follow-up five of these alerts during 2016-2017 to search for any optical transients that may be related to the neutrinos. Typically 10-20 faint m(ip1) less than or similar to 22.5 mag) extragalactic transients are found within the Pan-STARRS1 footprints and are generally consistent with being unrelated field supernovae (SNe) and AGN. We looked for unusual properties of the detected transients, such as temporal coincidence of explosion epoch with the IceCube timestamp, or other peculiar light curve and physical properties. We found only one transient that had properties worthy of a specific follow-up. In the Pan-STARRS1 imaging for IceCube-160427A (probability to be of astrophysical origin of similar to 50%), we found a SN PS16cgx, located at 10.0' from the nominal IceCube direction. Spectroscopic observations of PS16cgx showed that it was an H-poor SN at redshift z = 0.2895 +/- 0.0001. The spectra and light curve resemble some high-energy Type Ic SNe, raising the possibility of a jet driven SN with an explosion epoch temporally coincident with the neutrino detection. However, distinguishing Type Ia and Type Ic SNe at this redshift is notoriously difficult. Based on all available data we conclude that the transient is more likely to be a Type Ia with relatively weak Sin absorption and a fairly normal rest-frame r-band light curve. If, as predicted, there is no high-energy neutrino emission from Type Ia SNe, then PS16cgx must be a random coincidence, and unrelated to the IceCube-160427A. We find no other plausible optical transient for any of the five IceCube events observed down to a 5 sigma limiting magnitude of mip1 approximate to 22 mag, between 1 day and 25 days after detection

    A new integrated behavioural intervention for knee osteoarthritis: Development and pilot study

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    Background: Exercise-based approaches have been a cornerstone of physiotherapy management of knee osteoarthritis for many years. However, clinical effects are considered small to modest and the need for continued adherence identified as a barrier to clinical efficacy. While exercise-based approaches focus on muscle strengthening, biomechanical research has identified that people with knee osteoarthritis over activate their muscles during functional tasks. Therefore, we aimed to create a new behavioural intervention, which integrated psychologically informed practice with biofeedback training to reduce muscle overactivity, and which was suitable for delivery by a physiotherapist. Methods: Through literature review, we created a framework linking theory from pain science with emerging biomechanical concepts related to overactivity of the knee muscles. Using recognised behaviour change theory, we then mapped a set of intervention components which were iteratively developed through ongoing testing and consultation with patients and physiotherapists. Results: The underlying framework incorporated ideas related to central sensitisation, motor responses to pain and also focused on the idea that increased knee muscle overactivity could result from postural compensation. Building on these ideas, we created an intervention with five components: making sense of pain, general relaxation, postural deconstruction, responding differently to pain and functional muscle retraining. The intervention incorporated a range of animated instructional videos to communicate concepts related to pain and biomechanical theory and also used EMG biofeedback to facilitate visualization of muscle patterns. User feedback was positive with patients describing the intervention as enabling them to “create a new normal” and to be “in control of their own treatment.” Furthermore, large reductions in pain were observed from 11 patients who received a prototype version of the intervention. Conclusion: We have created a new intervention for knee osteoarthritis, designed to empower individuals with capability and motivation to change muscle activation patterns and beliefs associated with pain. We refer to this intervention as Cognitive Muscular Therapy. Preliminary feedback and clinical indications are positive, motivating future large-scale trials to understand potential efficacy. It is possible that this new approach could bring about improvements in the pain associated with knee osteoarthritis without the need for continued adherence to muscle strengthening programmes

    First T2K measurement of transverse kinematic imbalance in the muon-neutrino charged-current single-pi(+) production channel containing at least one proton

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    This paper reports the first T2K measurement of the transverse kinematic imbalance in the single- π + production channel of neutrino interactions. We measure the differential cross sections in the muon-neutrino charged-current interaction on hydrocarbon with a single π + and at least one proton in the final state, at the ND280 off axis near detector of the T2K experiment. The extracted cross sections are compared to the predictions from different neutrino-nucleus interaction event generators. Overall, the results show a preference for models that have a more realistic treatment of nuclear medium effects including the initial nuclear state and final-state interactions

    An early Oligocene age for the oldest known monkeys and rodents of South America

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    The Santa Rosa fossil locality in eastern Perú produced the first Paleogene vertebrate fauna from the Amazon Basin, including the oldest known monkeys from South America. This diverse paleofauna was originally assigned an Eocene age based largely on the stage of evolution of the site's caviomorph rodents and marsupials. Here, we present detrital zircon dates that indicate that the maximum composite age of Santa Rosa is 29.6 ± 0.08 Ma (Lower Oligocene), although several zircons from Santa Rosa date to the Upper Oligocene. The first appearance datum for Caviomorpha in South America is purported to be the CTA-27 site in the Contamana region of Perú, which is hypothesized to be ∼41 Ma (Middle Eocene) in age. However, the presence of the same caviomorph species and/or genera at both CTA-27 and at Santa Rosa is now difficult to reconcile with a >11-My age difference. To further test the Middle Eocene age estimate for CTA-27, we ran multiple Bayesian tip-dating analyses of Caviomorpha, treating the ages of all Paleogene species from Perú as unknown. These analyses produced mean age estimates for Santa Rosa that closely approximate the maximum 29.6 ± 0.08 Ma composite date provided by detrital zircons, but predict that CTA-27 is much younger than currently thought (∼30 Ma). We conclude that the ∼41 Ma age proposed for CTA-27 is incorrect, and that there are currently no compelling Eocene records of either rodents or primates in the known fossil record of South America

    Improved constraints on neutrino mixing from the T2K experiment with 3.13 x 10(21) protons on target

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    The T2K experiment reports updated measurements of neutrino and antineutrino oscillations using both appearance and disappearance channels. This result comes from an exposure of 14.9 ( 16.4 ) × 1 0 20 protons on target in neutrino (antineutrino) mode. Significant improvements have been made to the neutrino interaction model and far detector reconstruction. An extensive set of simulated data studies have also been performed to quantify the effect interaction model uncertainties have on the T2K oscillation parameter sensitivity. T2K performs multiple oscillation analyses that present both frequentist and Bayesian intervals for the Pontecorvo-Maki-Nakagawa-Sakata parameters. For fits including a constraint on sin 2 θ 13 from reactor data and assuming normal mass ordering T2K measures sin 2 θ 23 = 0.53 + 0.03 − 0.04 and Δ m 2 32 = ( 2.45 ± 0.07 ) × 10 − 3     eV 2   c − 4 . The Bayesian analyses show a weak preference for normal mass ordering (89% posterior probability) and the upper sin 2 θ 23 octant (80% posterior probability), with a uniform prior probability assumed in both cases. The T2K data exclude CP conservation in neutrino oscillations at the 2 σ level

    Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1.