Search for Periodic Time Variations of the Solar

We report a search for time variations of the solar ^{8}B neutrino flux using 5804 live days of Super-Kamiokande data collected between May 31, 1996, and May 30, 2018. Super-Kamiokande measured the precise time of each solar neutrino interaction over 22 calendar years to search for solar neutrino flux modulations with unprecedented precision. Periodic modulations are searched for in a dataset comprising five-day interval solar neutrino flux measurements with a maximum likelihood method. We also applied the Lomb-Scargle method to this dataset to compare it with previous reports. The only significant modulation found is due to the elliptic orbit of the Earth around the Sun. The observed modulation is consistent with astronomical data: we measured an eccentricity of (1.53±0.35)%, and a perihelion shift of (-1.5±13.5) days.

Search for Cosmic-Ray Boosted Sub-GeV Dark Matter Using Recoil Protons at Super-Kamiokande.

We report a search for cosmic-ray boosted dark matter with protons using the 0.37 megaton×years data collected at Super-Kamiokande experiment during the 1996-2018 period (SKI-IV phase). We searched for an excess of proton recoils above the atmospheric neutrino background from the vicinity of the Galactic Center. No such excess is observed, and limits are calculated for two reference models of dark matter with either a constant interaction cross section or through a scalar mediator. This is the first experimental search for boosted dark matter with hadrons using directional information. The results present the most stringent limits on cosmic-ray boosted dark matter and exclude the dark matter-nucleon elastic scattering cross section between 10^{-33}cm^{2} and 10^{-27}cm^{2} for dark matter mass from 1 MeV/c^{2} to 300 MeV/c^{2}.

Erratum: Search for Cosmic-Ray Boosted Sub-GeV Dark Matter Using Recoil Protons at Super-Kamiokande [Phys. Rev. Lett. 130, 031802 (2023)].

This corrects the article DOI: 10.1103/PhysRevLett.130.031802.

Search for Boosted Dark Matter Interacting with Electrons in Super-Kamiokande.

A search for boosted dark matter using 161.9 kt yr of Super-Kamiokande IV data is presented. We search for an excess of elastically scattered electrons above the atmospheric neutrino background, with a visible energy between 100 MeV and 1 TeV, pointing back to the Galactic center or the Sun. No such excess is observed. Limits on boosted dark matter event rates in multiple angular cones around the Galactic center and Sun are calculated. Limits are also calculated for a baseline model of boosted dark matter produced from cold dark matter annihilation or decay. This is the first experimental search for boosted dark matter from the Galactic center or the Sun interacting in a terrestrial detector.

Search for Nucleon and Dinucleon Decays with an Invisible Particle and a Charged Lepton in the Final State at the Super-Kamiokande Experiment.

Search results for nucleon decays p→e^{+}X, p→µ^{+}X, n→νγ (where X is an invisible, massless particle) as well as dinucleon decays np→e^{+}ν, np→µ^{+}ν, and np→τ^{+}ν in the Super-Kamiokande experiment are presented. Using single-ring data from an exposure of 273.4 kton·yr, a search for these decays yields a result consistent with no signal. Accordingly, lower limits on the partial lifetimes of τ_{p→e^{+}X}>7.9×10^{32} yr, τ_{p→µ^{+}X}>4.1×10^{32} yr, τ_{n→νγ}>5.5×10^{32} yr, τ_{np→e^{+}ν}>2.6×10^{32} yr, τ_{np→µ^{+}ν}>2.2×10^{32} yr, and τ_{np→τ^{+}ν}>2.9×10^{31} yr at a 90% confidence level are obtained. Some of these searches are novel.

Search for neutrinos from annihilation of captured low-mass dark matter particles in the sun by super-kamiokande.

Super-Kamiokande (SK) can search for weakly interacting massive particles (WIMPs) by detecting neutrinos produced from WIMP annihilations occurring inside the Sun. In this analysis, we include neutrino events with interaction vertices in the detector in addition to upward-going muons produced in the surrounding rock. Compared to the previous result, which used the upward-going muons only, the signal acceptances for light (few-GeV/c^{2}-200-GeV/c^{2}) WIMPs are significantly increased. We fit 3903 days of SK data to search for the contribution of neutrinos from WIMP annihilation in the Sun. We found no significant excess over expected atmospheric-neutrino background and the result is interpreted in terms of upper limits on WIMP-nucleon elastic scattering cross sections under different assumptions about the annihilation channel. We set the current best limits on the spin-dependent WIMP-proton cross section for WIMP masses below 200 GeV/c^{2} (at 10 GeV/c^{2}, 1.49×10^{-39} cm^{2} for χχ→bb[over ¯] and 1.31×10^{-40} cm^{2} for χχ→τ^{+}τ^{-} annihilation channels), also ruling out some fraction of WIMP candidates with spin-independent coupling in the few-GeV/c^{2} mass range.

Search for bosonic superweakly interacting massive dark matter particles with the XMASS-I detector.

Bosonic superweakly interacting massive particles (super-WIMPs) are a candidate for warm dark matter. With the absorption of such a boson by a xenon atom, these dark matter candidates would deposit an energy equivalent to their rest mass in the detector. This is the first direct detection experiment exploring the vector super-WIMPs in the mass range between 40 and 120 keV. With the use of 165.9 day of data, no significant excess above background was observed in the fiducial mass of 41 kg. The present limit for the vector super-WIMPs excludes the possibility that such particles constitute all of dark matter. The absence of a signal also provides the most stringent direct constraint on the coupling constant of pseudoscalar super-WIMPs to electrons. The unprecedented sensitivity was achieved exploiting the low background at a level 10(-4) kg-1 keVee-1 day-1 in the detector.

Search for trilepton nucleon decay via p→e+νν and p→µ+νν in the Super-Kamiokande experiment.

The trilepton nucleon decay modes p→e+νν and p→µ+νν violate |Δ(B-L)| by two units. Using data from a 273.4 kt yr exposure of Super-Kamiokande a search for these decays yields a fit consistent with no signal. Accordingly, lower limits on the partial lifetimes of τp→e+νν>1.7×10(32) years and τp→µ+νν>2.2×10(32) years at a 90% confidence level are obtained. These limits can constrain Grand Unified Theories which allow for such processes.

Search for nucleon decay via n→ν[over ¯]π0 and p→ν[over ¯]π+ in Super-Kamiokande.

We present the results of searches for nucleon decay via n→ν[over ¯]π0 and p→ν[over ¯]π+ using data from a combined 172.8 kt·yr exposure of Super-Kamiokande-I,-II, and-III. We set lower limits on the partial lifetime for each of these modes: τn→ν[over ¯]π0>1.1×10(33) years and τp→ν[over ¯]π+>3.9×10(32) years at a 90% confidence level.

First indication of terrestrial matter effects on solar neutrino oscillation.

We report an indication that the elastic scattering rate of solar B8 neutrinos with electrons in the Super-Kamiokande detector is larger when the neutrinos pass through Earth during nighttime. We determine the day-night asymmetry, defined as the difference of the average day rate and average night rate divided by the average of those two rates, to be [-3.2 ± 1.1(stat) ± 0.5(syst)]%, which deviates from zero by 2.7 σ. Since the elastic scattering process is mostly sensitive to electron-flavored solar neutrinos, a nonzero day-night asymmetry implies that the flavor oscillations of solar neutrinos are affected by the presence of matter within the neutrinos' flight path. Super-Kamiokande's day-night asymmetry is consistent with neutrino oscillations for 4 × 10(-5) eV(2) ≤ Δm 2(21) ≤ 7 × 10(-5) eV(2) and large mixing values of θ12, at the 68% C.L.

Search for dinucleon decay into kaons in Super-Kamiokande.

A search for the dinucleon decay pp → K+ K+ has been performed using 91.6 kton·yr data from Super-Kamiokande-I. This decay provides a sensitive probe of the R-parity-violating parameter λ112''. A boosted decision tree analysis found no signal candidates in the data. The expected background was 0.28±0.19 atmospheric neutrino induced events and the estimated signal detection efficiency was 12.6%±3.2%. A lower limit of 1.7×10(32) years has been placed on the partial lifetime of the decay O16 → C14K+ K+ at 90% C.L. A corresponding upper limit of 7.8×10(-9) has been placed on the parameter λ112''.

Evidence for the appearance of atmospheric tau neutrinos in super-Kamiokande.

Super-Kamiokande atmospheric neutrino data were fit with an unbinned maximum likelihood method to search for the appearance of tau leptons resulting from the interactions of oscillation-generated tau neutrinos in the detector. Relative to the expectation of unity, the tau normalization is found to be 1.42 ± 0.35(stat)(-0.12)(+0.14)(syst) excluding the no-tau-appearance hypothesis, for which the normalization would be zero, at the 3.8σ level. We estimate that 180.1 ± 44.3(stat)(-15.2)(+17.8) (syst) tau leptons were produced in the 22.5 kton fiducial volume of the detector by tau neutrinos during the 2806 day running period. In future analyses, this large sample of selected tau events will allow the study of charged current tau neutrino interaction physics with oscillation produced tau neutrinos.

Search for differences in oscillation parameters for atmospheric neutrinos and antineutrinos at Super-Kamiokande.

We present a search for differences in the oscillations of antineutrinos and neutrinos in the Super-Kamiokande-I, -II, and -III atmospheric neutrino sample. Under a two-flavor disappearance model with separate mixing parameters between neutrinos and antineutrinos, we find no evidence for a difference in oscillation parameters. Best-fit antineutrino mixing is found to be at (Δm2,sin2 2θ)=(2.0×10(-3) eV2, 1.0) and is consistent with the overall Super-K measurement.

Effectiveness of a comprehensive oral management protocol for the prevention of severe oral mucositis in patients receiving radiotherapy with or without chemotherapy for oral cancer: a multicentre, phase II, randomized controlled trial.

The aim of this phase II, multicentre, randomized controlled trial was to evaluate the effectiveness of a comprehensive oral management protocol for the prevention of severe oral mucositis in patients with oral cancer receiving radiotherapy alone or chemoradiotherapy. In total, 124 patients with oral cancer were enrolled from five institutions. Of these, 37 patients undergoing radiotherapy were randomly divided into an intervention group (n=18) and a control group (n=19). The remaining 87 patients, who were undergoing chemoradiotherapy, were also randomized into an intervention group (n=42) and a control group (n=45). During radiotherapy, patients in the control group received only oral care, while those in the intervention group additionally received spacers to cover the entire dentition, pilocarpine hydrochloride, and topical dexamethasone ointment for oral mucositis. The primary endpoint was the incidence of severe oral mucositis. The intervention was significantly associated with a decreased incidence of severe oral mucositis in patients receiving radiotherapy alone (P=0.046), but not in those receiving chemoradiotherapy (P=0.815). These findings suggest that an oral management protocol can prevent severe oral mucositis in patients with oral cancer undergoing radiotherapy without concurrent chemotherapy.

Injectable growth/differentiation factor-5-recombinant human collagen composite induces endochondral ossification via Sry-related HMG box 9 (Sox9)expression and angiogenesis in murine calvariae.

BACKGROUND AND OBJECTIVE: The types of collagens available today as biomaterials are purified from animal tissues. A major growing concern, however, is their safety, since there are risks of viral and prion contamination and of unknown and potentially zoonotic infectious diseases. The present study aimed to assess, using immunohistochemistry, the effects of recombinant human growth/differentiation factor-5 (rhGDF-5) combined with recombinant human collagen I (rhCI) on bone formation in murine calvariae. MATERIAL AND METHODS: Composite rhGDF-5-rhCI or rhCI alone was injected subcutaneously into murine calvariae. After 3, 7 or 14 days, tissues were examined radiologically, histologically and immunohistochemically. The production of vascular endothelial growth factor (VEGF) by primary osteoblasts, periosteal cells and connective tissue fibroblasts isolated enzymatically from neonatal murine calvariae was also assessed. RESULTS: A protrusion was observed on the calvariae at the site injected with rhGDF-5/rhCI composite. Its mineral density was shown to be different from that of the existing bone by two-dimensional microcomputed tomography. Type II collagen-positive staining was restricted to newly formed tissues. Thus, the newly formed tissues seemed to be bone- and cartilage-like tissues. A number of vessels with positively stained cells for Von Willebrand factor were detected in the newly formed tissues. The rhGDF-5 enhanced VEGF production in cultured connective tissue fibroblasts. Sry-related HMG box 9 (Sox9)-positive cells were detected in the hypertrophic periosteum, and penetrated into the newly formed tissues. CONCLUSIONS: These results suggest that rhCI seems to allow the release of rhGDF-5 and that rhGDF-5-rhCI composite induces endochondral ossification via Sox9 expression and angiogenesis in murine calvariae.

Correction osteotomy for malunion of the talar head: a case report.

Talar head fractures are rare injuries. We present a 26-year-old man with malunion of the talar head. The displaced fracture was initially neglected. The patient was treated with osteotomy and bone grafting to improve the congruity and movement of the talonavicular joint. Three months after surgery, he returned to his pre-injury activity level with no disability.

Pigmented villonodular synovitis of the elbow in a 6-year-old girl: a case report.

Pigmented villonodular synovitis of the elbow is rare and even rarer in children. We report a case of pigmented villonodular synovitis of the elbow in a 6-year-old girl who underwent total synovectomy after the diagnosis was confirmed by biopsy. The osteochondral defect at the olecranon was filled with calcium phosphate bone paste. Two years after surgery, neither recurrence nor joint degeneration was found.

Tarsal tunnel syndrome caused by a talocalcaneal joint amyloidoma in a long-term haemodialysis patient: a case report.

We present a case of tarsal tunnel syndrome caused by an amyloidoma arising from the talocalcaneal joint in a 64-year-old man with a long history of haemodialysis. He presented with numbness in the medial plantar area of the right foot without any antecedent trauma. The numbness was minimal at rest but gradually worsened, causing difficulty, when walking. Paraesthesia was present on the medial sole of the right foot. A positive Tinel-like sign was noted 2.5 cm below the medial malleolus. Magnetic resonance imaging demonstrated a round lesion, 1 cm in diameter, in the calcaneus, which was hypointense on T1-weighted images and hyperintense on T2-weighted images. In addition, a mass, 1 cm in diameter with a signal isointense to that of muscle was found adjacent to the talocalcaneal joint. The medial plantar nerve was decompressed after removing a solid, 1-cm diameter mass from the talocalcaneal joint. At 6 months post surgery, the numbness had completely resolved. No recurrence was observed at the 24-month follow-up.

Saddle embolism after corrective femoral osteotomy: a case report.

We present a case of recurrent saddle embolism 6 days and 9 days following corrective osteotomy of the left femur in a 64-year-old man with a history of atrial fibrillation. Although saddle embolism is a relatively rare event, orthopaedic surgeons should be aware of this condition.

Support for an explanation of the guidance effect in motor skill learning.

The authors investigated whether the knowledge of results (KR) schedule influences the extent to which intrinsic feedback is noticed and used. Fifty-six participants received KR that was either delayed over 2 trials (Delay-2) or provided directly after each trial (Delay-0) during 160 trials of an unfamiliar aiming task. No-KR retention tests were given after 80 trials and 1 min and 24 hr after the end of acquisition. After retention, all participants were questioned about their use of intrinsic feedback during practice and whether those sources changed as a function of practice. The Delay-2 group performed significantly less accurately on the 1st and last blocks of acquisition trials but showed a significantly smaller performance decline from acquisition to retention. Moreover, the Delay-2 group noticed and used a greater variety of intrinsic feedback sources and its members were more likely to report that their usage changed with practice.