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 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.

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.

[Clinical trial of fadrozole hydrochloride for postmenopausal patients with recurrent breast cancer].

Eleven recurrent postmenopausal breast cancer patients with osseous or lung metastases were received fadrozole hydrochloride at a dose of 1 mg twice a day for more than 8 weeks. The median disease-free interval of these 11 patients with metastasis was 74 months. Out of 11 evaluable cases, 2 PR, 6 long-NC and 3 PD were observed. The overall response rate was 18.2% and the long-NC rate was 54.5%. The average overall duration of responses and long-NC were 567 days and 573 days, respectively. There was no adverse drug reaction. A combination therapy with fadrozole hydrochloride 2 mg daily and cyclophosphamide 100 mg orally on days 1-14 was given to 14 postmenopausal patients with recurrent breast cancer. The median disease-free interval of these 14 patients with metastasis was 33 months. There were 2 CR, 3 PR, 4 long-NC, 2 NC and 3 PD. The overall response rate and long-NC rate were 35.8% and 28.6%, respectively. The average overall duration of responses and long-NC were 700 days and 443 days, respectively. The adverse drug reactions were anorexia (Grade 2) and neutropenia (Grade 1 and 2). These results suggested that a combination therapy with fadrozole hydrochloride and cyclophosphamide can be effective and contribute to survival time in the treatment of postmenopausal breast cancer.

[A case of acinar-islet cell tumor of the pancreas body].

Combined carcinoma of the pancreas is very rare. The case of pancreatic tumor featuring both acinar cell and islet cell tumors presented, may be only the fifth case of acinar-islet cell tumor in the world. A 34-year-old-woman visited our hospital complaining of weight loss (8 kg/6 months). A clearly demarcated pancreatic tumor was visualized by ultrasonography, body CT and MRI. Class 3 cells were extracted via ultrasonography guided fine-needle biopsy. Tumor was enucleated on October 5, 1988. Histologic appearance of the tumor by light microscopy was consistent with that of both acinar cell and islet cell tumors. Electron microscopy revealed two distinct populations of zymogen and neuroendocrine granules. The patient is doing well 1 year and 7 months postoperatively with no evidence of liver metastasis or recurrence. This case is significant in terms of the close histogenic relationship between pancreatic exocrine and endocrine components.

Translocation t(12;16)(q13;p11) in myxoid liposarcoma of a child and implication of the human int-1 gene in tumorigenesis.

Cytogenetic and gene analyses were performed in a child with myxoid liposarcoma (MLS). A reciprocal chromosome translocation t(12;16)(q13;p11) was found in the tumor cells. This result, combined with the previous reports of a similar translocation in adult MLS strongly suggests that this translocation may be a characteristic cytogenetic marker in MLS. The human int-1 gene has been reported to be located close to the 12q13 breakpoint associated with MLS. Therefore, we examined the rearrangement of the human int-1 gene by Southern blotting analysis. When genomic DNAs from the tumor cells were digested with KpnI, EcoRI and BamHI, no difference was seen compared to peripheral blood leukocytes (PBL) DNAs from a normal individual. However, with HindIII digestion there appeared a 3.1 kb fragment in tumor cell DNA as compared to a 2.8 kb fragment in DNAs prepared from normal PBL and the patient's PBL. These findings suggest that the int-1 gene may be implicated in tumorigenesis of MLS with t(12;16)(q13;p11).