Search for the Majorana Nature of Neutrinos in the Inverted Mass Ordering Region with KamLAND-Zen.

The KamLAND-Zen experiment has provided stringent constraints on the neutrinoless double-beta (0νßß) decay half-life in ^{136}Xe using a xenon-loaded liquid scintillator. We report an improved search using an upgraded detector with almost double the amount of xenon and an ultralow radioactivity container, corresponding to an exposure of 970 kg yr of ^{136}Xe. These new data provide valuable insight into backgrounds, especially from cosmic muon spallation of xenon, and have required the use of novel background rejection techniques. We obtain a lower limit for the 0νßß decay half-life of T_{1/2}^{0ν}>2.3×10^{26} yr at 90% C.L., corresponding to upper limits on the effective Majorana neutrino mass of 36-156 meV using commonly adopted nuclear matrix element calculations.

Precision Analysis of the

We present a precision analysis of the ^{136}Xe two-neutrino ßß electron spectrum above 0.8 MeV, based on high-statistics data obtained with the KamLAND-Zen experiment. An improved formalism for the two-neutrino ßß rate allows us to measure the ratio of the leading and subleading 2νßß nuclear matrix elements (NMEs), ξ_{31}^{2ν}=-0.26_{-0.25}^{+0.31}. Theoretical predictions from the nuclear shell model and the majority of the quasiparticle random-phase approximation (QRPA) calculations are consistent with the experimental limit. However, part of the ξ_{31}^{2ν} range allowed by the QRPA is excluded by the present measurement at the 90% confidence level. Our analysis reveals that predicted ξ_{31}^{2ν} values are sensitive to the quenching of NMEs and the competing contributions from low- and high-energy states in the intermediate nucleus. Because these aspects are also at play in neutrinoless ßß decay, ξ_{31}^{2ν} provides new insights toward reliable neutrinoless ßß NMEs.

VALIDATION OF MONTE CARLO DOSE CALCULATION FOR PAEDIATRIC CT EXAMINATIONS USING TUBE CURRENT MODULATION BASED ON IN-PHANTOM DOSIMETRY.

The aim of this study is to estimate tube current modulation (TCM) profiles in paediatric computed tomography (CT) examinations with a TCM scheme (Volume-EC) and evaluate the estimation accuracy of TCM profiles. Another aim is to validate organ doses calculated using Monte Carlo-based CT dosimetry software and estimated TCM profiles by comparing them with those measured using 5-year-old and 10-year-old anthropomorphic phantoms and radio-photoluminescence glass dosemeters. Dose calculations were performed by inputting detailed descriptions of a CT scanner, scan parameters and CT images of the phantoms into the software. Organ doses were evaluated from the calculated dose distribution images. Average relative differences (RDs) between the estimated and actual TCM profiles ranged from -3.6 to 5.6%. RDs between the calculated and measured organ doses ranged from -4.2 to 13.0% and -18.1 to 4.9% for 5-year-old and 10-year-old phantoms, respectively. These results validate dose calculations for paediatric CT scans using TCM.

Organ Dose Evaluations Based on Monte Carlo Simulation for CT Examinations Using Tube Current Modulation.

The aims of this study were to estimate tube current values for each X-ray projection angle used in adult chest computed tomography (CT) and abdomen-pelvis CT examinations with tube current modulation (TCM) and to validate organ doses determined using Monte Carlo (MC) simulations through comparisons with the doses measured using in-phantom dosimetry. For dose simulations, dose distribution images were obtained by inputting the geometry of a CT scanner, scan parameters including estimated TCM curves and CT images of an adult anthropomorphic phantom into MC simulation software. Organ doses were then determined from the dose distribution images. For dose measurements, organ doses were evaluated using radio-photoluminescence glass dosemeters located at various organ positions within the phantom. Relative differences between the simulated and measured organ doses were -2.5 to 11.0% and -1.5 to 10.5% for organs in chest and abdomen-pelvis CT scan ranges, respectively. Thus, the simulated and measured doses agreed well.

Publisher's Note: Search for Majorana Neutrinos Near the Inverted Mass Hierarchy Region with KamLAND-Zen [Phys. Rev. Lett. 117, 082503 (2016)].

This corrects the article DOI: 10.1103/PhysRevLett.117.082503.

Search for Majorana Neutrinos Near the Inverted Mass Hierarchy Region with KamLAND-Zen.

We present an improved search for neutrinoless double-beta (0νßß) decay of ^{136}Xe in the KamLAND-Zen experiment. Owing to purification of the xenon-loaded liquid scintillator, we achieved a significant reduction of the ^{110m}Ag contaminant identified in previous searches. Combining the results from the first and second phase, we obtain a lower limit for the 0νßß decay half-life of T_{1/2}^{0ν}>1.07×10^{26} yr at 90% C.L., an almost sixfold improvement over previous limits. Using commonly adopted nuclear matrix element calculations, the corresponding upper limits on the effective Majorana neutrino mass are in the range 61-165 meV. For the most optimistic nuclear matrix elements, this limit reaches the bottom of the quasidegenerate neutrino mass region.

DEVELOPMENT OF AGE-SPECIFIC JAPANESE PHYSICAL PHANTOMS FOR DOSE EVALUATION IN INFANT CT EXAMINATIONS.

Secondary to the previous development of age-specific Japanese head phantoms, the authors designed Japanese torso phantoms for dose assessment in infant computed tomography (CT) examinations and completed a Japanese 3-y-old head-torso phantom. For design of age-specific torso phantoms (0, 0.5, 1 and 3 y old), anatomical structures were measured from CT images of Japanese infant patients. From the CT morphometry, it was found that rib cages of Japanese infants were smaller than those in Europeans and Americans. Radiophotoluminescence glass dosemeters were used for dose measurement of a 3-y-old head-torso phantom. To examine the validity of the developed phantom, organ and effective doses by the in-phantom dosimetry system were compared with simulation values in a web-based CT dose calculation system (WAZA-ARI). The differences in doses between the two systems were <20 % at the doses of organs within scan regions and effective doses in head, chest and abdominopelvic CT examinations.

Optimised paediatric CT dose at a tertiary children's hospital in Japan: a 4-y single-centre analysis.

Since diagnostic reference levels (DRLs) for children are not currently established in Japan, the authors determined local DRLs for the full range of paediatric CT examinations in a single tertiary care children's hospital. A retrospective review of 4801 CT performance records for paediatric patients (<15 y old) who had undergone CT examinations from 2008 to 2011 was conducted. The most frequent examinations were of the head (52 %), followed by cardiac (15 %), temporal bone (9 %), abdomen (7 %), chest (6 %) and others (11 %). Approximately one-third of children received two or more CT scans. The authors' investigation showed that mean CTDIvol and DLP for head, chest and abdomen increased as a function of age. Benchmarking of the results showed that CTDIvol, DLP and effective dose for chest and abdomen examinations in this hospital were below average, whereas those for the head tended to be at or slightly above average of established DRL values from five countries. The results suggest that CT examinations as performed in a tertiary children's hospital in Japan are well optimised.

Enhancing a sedation score to include truly noxious stimulation: the Extended Observer's Assessment of Alertness and Sedation (EOAA/S).

BACKGROUND: Although the Modified Observer's Assessment of Alertness and Sedation (MOAA/S) is frequently used in sedation-related drug and device studies, a major shortcoming is that it does not differentiate between lighter and deeper levels of general anaesthesia because the only noxious stimulus of the MOAA/S is a trapezius squeeze. The primary aim of this investigation was to expand the MOAA/S score to include truly noxious stimulation, thereby extending the dynamic range of the assessment to include sedation states consistent with deeper levels of general anaesthesia. METHODS: Twenty healthy volunteers received target controlled infusions of fentanyl (target=0.8 ng ml(-1)) and propofol (starting at 0.5 µg ml(-1) and gradually increasing to 5 µg ml(-1)). At each propofol concentration, a MOAA/S score was obtained before and after tetanic electrical stimulation. The tetanic electrical stimulation current was gradually increased until the subject responded or until 50 mA was delivered without a response. A pharmacodynamic model was constructed to characterize the concentration-effect relationship between propofol and the MOAA/S scores. RESULTS: All subjects required a significantly higher propofol concentration to produce unresponsiveness to tetanic electrical stimulation at 50 mA compared with a standardized trapezius squeeze. The pharmacodynamic model adequately characterized the concentration-effect relationship. CONCLUSIONS: The Extended Observer's Assessment of Alertness and Sedation (or EOAA/S) extends the range of the widely used MOAA/S score to include truly noxious stimulation, thereby enabling the identification of drug-induced central nervous system depression representative of surgical anaesthesia.

Evaluation of organ doses in adult and paediatric CT examinations based on Monte Carlo simulations and in-phantom dosimetry.

The aim of this study was to validate the computed tomography dose index (CTDI) and organ doses evaluated by Monte Carlo simulations through comparisons with doses evaluated by in-phantom dosimetry. Organ doses were measured with radio-photoluminescence glass dosemeter (RGD) set at various organ positions within adult and 1-y-old anthropomorphic phantoms. For the dose simulations, the X-ray spectrum and bow-tie filter shape of a CT scanner were estimated and 3D voxelised data of the CTDI and anthropomorphic phantoms from the acquired CT images were derived. Organ dose simulations and measurements were performed with chest and abdomen-pelvis CT examination scan parameters. Relative differences between the simulated and measured doses were within 5 % for the volume CTDI and 13 % for organ doses for organs within the scan range in adult and paediatric CT examinations. The simulation results were considered to be in good agreement with the measured doses.

Development of age-specific Japanese head phantoms for dose evaluation in paediatric head CT examinations.

In this study, the authors developed age-specific physical head phantoms simulating the physique of Japanese children for dose evaluation in paediatric head computed tomography (CT) examinations. Anatomical structures at 99 places in 0-, 0.5-, 1- and 3-y-old Japanese patients were measured using DICOM viewer software from CT images, and the head phantom of each age was designed. For trial manufacture, a 3-y-old head phantom consisting of acrylic resin and gypsum was produced by machine processing. Radiation doses for the head phantom were measured with radiophotoluminescence glass dosemeters and Si-pin photodiode dosemeters. To investigate whether the phantom shape was suitable for dose evaluation, organ doses in the same scan protocol were compared between the 3-y-old head and commercially available anthropomorphic phantoms having approximately the same head size. The doses of organs in both phantoms were equivalent. The authors' designed paediatric head phantom will be useful for dose evaluation in paediatric head CT examinations.

Potential egg contamination by Salmonella enterica serovar Typhimurium definitive type 104 following experimental infection of pullets at the onset of lay.

The present study investigated the potential of Salmonella enterica serovar Typhimurium (Salmonella Typhimurium) definitive type 104 (DT104) to contaminate eggs in vivo. Of 10 strains of Salmonella Typhimurium DT104, none caused egg contamination when hens were inoculated orally. Three passages of the strains through recovery from the reproductive organs of intravenously infected laying hens resulted in no egg contamination after oral infection of the hens. Feed and water withdrawal for 24 h at 5 and 10 d after oral infection with Salmonella Typhimurium DT104 slightly decreased egg production but did not lead to egg contamination. Finally, oral infection of pullets at the onset of lay (approximately 50% of egg production) resulted in egg contamination (1.7%) in 2 wk. In conclusion, the Salmonella Typhimurium DT104 strains used in the present study have a low possibility of causing egg contamination; however, because infection at the onset of lay can cause egg contamination, the introduction of Salmonella Typhimurium DT104 into the layer houses should be prevented, especially when hens start laying eggs.

Successful non-T-cell-depleted nonmyeloablative hematopoietic stem cell transplantation (NST) from an HLA-haploidentical 2-loci-mismatched sibling in a heavily transfused patient with severe aplastic anemia based on the fetomaternal microchimerism.

A 37-year-old Japanese man with systemic hemochromatosis due to multiple transfusions was referred to us for the treatment of severe aplastic anemia (SAA), from which he had been suffering for 24 years. The patient had diabetes arising from the hemochromatosis, chronic anal fissures, and a kidney abscess due to neutropenia. He was treated with a nonmyeloablative preconditioning regimen followed by non-T-cell-depleted (non-TCD) allogeneic peripheral blood stem cell transplantation (PBSCT) from his human leukocyte antigen (HLA)-haploidentical 2-loci-mismatched sibling. Prompt engraftment of granulocytes and platelets was observed, and graft-versus-host disease was easy to control. Noninherited maternal antigens in the donor were confirmed prior to PBSCT, and they were also detected in small quantities in the recipient. This report describes the first successful nonmyeloablative hematopoietic stem cell transplant in a heavily transfused SAA patient from an HLA-haploidentical 2-loci-mismatched sibling donor. The result suggests that a long-term fetomaternal microchimerism-positive sibling can be a second-line donor if an alternative HLA-identical donor is not available.

Monitoring of T-cell repertoire was useful for predicting graft-versus-host disease prognosis in a patient with chronic myelogeneous leukemia after allogeneic bone marrow transplantation.

We analyzed 24 T-cell receptor (TCR)beta chain subfamilies (Vbeta) and the chimerism of a patient with chronic myelogeneous leukemia who underwent allogeneic bone marrow transplantation (allo-BMT). The patient developed liver dysfunction at day 19 leading to worsening of his condition. He died on day 91 of hepatic failure. Complete donor chimerism was observed after day 19. The average complexity score of TCR-Vbeta, which was low on day 19 (5.50), because much lower on day 82 (3.77). The average value of normal volunteers is 7.69. Neither immunosuppressive therapy nor antiviral therapy was effective to treat his hepatic dysfunction. A liver specimen at autopsy showed necrotic tissue with invasion of lymphocytes under the endothelial cells of the bile ducts. These findings suggest that the liver dysfunction was due to graft-versus-host disease (GVHD). Careful monitoring of chimerism and TCR-Vbeta complexity may help to predict the prognosis of GVHD after allogeneic BMT.

Possible efficacy of lamivudine treatment to prevent hepatitis B virus reactivation due to rituximab therapy in a patient with non-Hodgkin's lymphoma.

We used regimens containing rituximab in the treatment of five hepatitis B virus surface antibody (HBsAb)-positive patients with non-Hodgkin's lymphoma (NHL). Serum levels of HBsAb were obtained and analyzed in four of these patients. Two patients were HBs antigen (HBsAg) positive. One of these HBsAg-positive patients was treated with lamivudine because the patient developed fulminant hepatitis from hepatitis B virus (HBV) infection prior to chemotherapy. However, none of the other patients were administered lamivudine. An HBsAg-positive patient who did not receive lamivudine treatment later developed fulminant hepatitis. Another HBsAg-positive patient receiving lamivudine prophylaxis did not develop severe hepatitis arising from HBV. In the three patients not receiving lamivudine treatment, serum HBsAb titers decreased soon after the administration of rituximab. These results suggest that rituximab reduced the antibody titer for HBV, thus inducing an immunological environment leading to easy reactivation of HBV. Lamivudine prophylaxis was effective, at least when rituximab was given to an HBsAg-positive patient with non-Hodgkin's lymphoma.