Abstract
X-ray timing properties of the magnetar SGR 1900+14 were studied, using the data taken with Suzaku in 2009 and NuSTAR in 2016, for a time lapse of 114 and 242 ks, respectively. On both ...occasions, the object exhibited the characteristic two-component spectrum. The soft component, dominant in energies below ∼5 keV, showed a regular pulsation, with a period of
P
= 5.21006 s as determined with the Suzaku XIS, and
P
= 5.22669 with NuSTAR. However, in ≳ 6 keV where the hard component dominates, the pulsation became detectable with the Suzaku HXD and NuSTAR only after the data were corrected for periodic pulse-phase modulation, with a period of
T
= 40 − 44 ks and an amplitude of ≈1 s. Further correcting the two data sets for complex energy dependences in the phase modulation parameters, the hard X-ray pulsation became fully detectable, in 12–50 keV with the HXD and 6–60 keV with NuSTAR, using a common value of
T
= 40.5 ± 0.8 ks. Thus, SGR 1900+14 becomes a third example, after 4U 0142+61 and 1E 1547−5408, to show the hard X-ray pulse-phase modulation, and a second case of energy dependences in the modulation parameters. The neutron star in this system is inferred to perform free precession, as it is axially deformed by ≈
P
/
T
= 1.3 × 10
−4
, presumably due to ∼ 10
16
G toroidal magnetic fields. As a counterexample, the Suzaku data of the binary pulsar 4U 1626−67 were analyzed, but no similar effect was found. These results altogether argue against the accretion scenario for magnetars.
Abstract
Study question
Can the gas-liquid interface organ culture system that achieved in vitro spermatogenesis in mice also support in vitro spermatogenesis in human adult testis?
Summary answer
...Although the progression of spermatogenesis was not observed, germ cells were maintained without the degeneration of the architecture in both fresh and cryopreserved testicular tissues.
What is known already
Although the research on in vitro spermatogenesis have been conducted for 100 years, only the organ culture system using gas-liquid interface method achieved in vitro spermatogenesis in mice. It has not been verified whether this culture system can be applied to other mammals including humans and induce spermatogenesis.
Study design, size, duration
Testicular tissue was obtained from the transgender patients receiving sex reassignment surgery. Testicular specimens were either immediately processed for cultivation or cryopreserved, using a vitrification freezing protocol. Organ culture of testicular fragments was performed in three different media for a maximum period of 3 weeks to evaluate the short-term changes in the cultured tissues (viability, proliferation and maintenance of germ and somatic cells).
Participants/materials, setting, methods
Fresh and cryopreserved-thawed testis fragments (1–2 mm3) were cultured using the organ culture system in alpha-MEM with knock-out serum replacement (K group), alpha-MEM with lipid-rich BSA (A group) and DMEM with FBS (D group). Luteinizing hormone, follicle stimulating hormone and testosterone were supplemented. The number of germ cells (using DDX4), proliferative activity of germ cells (using EdU assay) and intratubular cell apoptosis (by TdT-mediated dUTP Nick End Labeling) were evaluated by immunohistochemical staining weekly.
Main results and the role of chance
The architecture of the seminiferous tubules was maintained until the second week of culture in both the fresh and the cryopreserved culture group. The number of DDX4-positive germ cells per seminiferous tubule in groups D, K, and A was 49 ± 24, 55 ± 21, 50 ± 26 cells/tubule in 1 day, 32 ± 13, 42 ± 7, 36 ± 21 cells/tubule in 1week, respectively. The numbers gradually decreased to 26 ± 8, 24 ± 6 and 27 ± 18 cells/tubule, in 2 weeks, respectively, with no difference among the groups. The number of intratubular EdU-positive cells of groups D, K, and A was 0.2 ± 0.2, 2.8 ± 2.1, 1.1 ± 0.8 cells/tubule at 1 day, 0.1 ± 0.2, 0.5 ± 0.6, 0.3 ± 0.6 cells/tubule at 1 week, respectively. The values were 0.01, 0.05, and 0.03 at 2 weeks. Thus, EdU-positive cells drastically decreased from the first week of culture. The number of DDX4-positive germ cells and the intratubular EdU-positive cells in the cryopreserved culture group was not different from that in the fresh culture group.
Limitations, reasons for caution
Current organ culture systems are incomplete, being unable to induce human in vitro spermatogenesis. Further research is needed to improve culture condition with the aim of producing fertile sperm of infertile adult male patients.
Wider implications of the findings: Our organ culture system could maintain testis structure and germ cells. By using the testis tissues of the transgender patients, which are available with their consent, we will promote the investigation of the culture condition necessary for germ cell proliferation and differentiation.
Trial registration number
Grant-in-Aid for Scientific Research on Innovative Areas 18H05546, Grant-in-Aid for Young Scientists (A) 17H05098 and Takeda Science Foundation
We report simulation results of photonuclear reactions in the atmosphere triggered by a downward terrestrial gamma ray flash in lightning. Possible channels of reactions in the atmosphere and their ...cross‐sections are verified with the ENDF/B‐VII.1 library. Monte Carlo simulations with two stages are then performed with the Geant4 framework. In the first stage, electrons following the relativistic runaway electron avalanche spectrum are produced in a mass model of the atmosphere, and production of photoneutrons and β+‐decay nuclei is calculated based on the nuclear data library. In total 1 × 1013 neutrons and 4 × 1012 β+‐decay nuclei are produced by 1018 energetic electrons above 1 MeV. In the second stage, propagation of the photoneutrons and positrons from the β+‐decay nuclei in the previous stage is calculated. As a result, we model on‐ground distributions of fluxes and energy spectra for neutrons, neutron‐related gamma rays, and annihilation ones. The simulation model is to be compared with photonuclear events detected in low‐charge‐center winter thunderstorms.
Plain Language Summary
Lightning discharges occasionally emit a powerful flash of gamma rays called terrestrial gamma ray flashes. Gamma rays in terrestrial gamma ray flashes have high energies enough to react with atmospheric nuclei such as nitrogen and oxygen. The nuclear reactions in the atmosphere produce neutrons and unstable isotopes that emit positrons. In this paper, we utilize a Monte Carlo simulation framework, calculate a series of reactions and processes in the atmosphere, and then construct a distribution model of neutrons, neutron‐related gamma rays, and positron‐related ones at ground level. The obtained model can be compared with recent observations of nuclear reactions during winter thunderstorms in Japan.
Key Points
Possible channels of atmospheric photonuclear reactions in lightning are surveyed from a nuclear‐reaction data library
Monte Carlo calculations are performed to simulate photoneutron and β+‐decay‐nuclide productions in the atmosphere
On‐ground distributions of fluxes and spectra for neutrons, neutron‐related gamma rays, and annihilation gamma rays are modeled
Background and purpose: Alogliptin, a highly selective dipeptidyl peptidase‐4 (DPP‐4) inhibitor, enhances incretin action and pioglitazone enhances hepatic and peripheral insulin actions. Here, we ...have evaluated the effects of combining these agents in diabetic mice.
Experimental approach: Effects of short‐term treatment with alogliptin alone (0.01%–0.1% in diet), and chronic combination treatment with alogliptin (0.03% in diet) and pioglitazone (0.0075% in diet) were evaluated in db/db mice exhibiting early stages of diabetes.
Key results: Alogliptin inhibited plasma DPP‐4 activity up to 84% and increased plasma active glucagon‐like peptide‐1 by 4.4‐ to 4.9‐fold. Unexpectedly, alogliptin alone lacked clear efficacy for improving glucose levels. However, alogliptin in combination with pioglitazone clearly enhanced the effects of pioglitazone alone. After 3–4 weeks of treatment, combination treatment increased plasma insulin by 3.8‐fold, decreased plasma glucagon by 41%, both of which were greater than each drug alone, and increased plasma adiponectin by 2.4‐fold. In addition, combination treatment decreased glycosylated haemoglobin by 2.2%, plasma glucose by 52%, plasma triglycerides by 77% and non‐esterified fatty acids by 48%, all of which were greater than each drug alone. Combination treatment also increased expression of insulin and pancreatic and duodenal homeobox 1 (PDX1), maintained normal β‐cell/α‐cell distribution in islets and restored pancreatic insulin content to levels comparable to non‐diabetic mice.
Conclusions and implications: These results indicate that combination treatment with alogliptin and pioglitazone at an early stage of diabetes improved metabolic profiles and indices that measure β‐cell function, and maintained islet structure in db/db mice, compared with either alogliptin or pioglitazone monotherapy.
We developed CdTe double-sided strip detectors (DSDs or cross strip detectors) and evaluated their spectral and imaging performance for hard X-rays and gamma-rays. Though the double-sided strip ...configuration is suitable for imagers with a fine position resolution and a large detection area, CdTe diode DSDs with indium (In) anodes have yet to be realized due to the difficulty posed by the segmented In anodes. CdTe diode devices with aluminum (Al) anodes were recently established, followed by a CdTe device in which the Al anodes could be segmented into strips. We developed CdTe double-sided strip devices having Pt cathode strips and Al anode strips, and assembled prototype CdTe DSDs. These prototypes have a strip pitch of 400 mum. Signals from the strips are processed with analog ASICs (application specific integrated circuits). We have successfully performed gamma-ray imaging spectroscopy with a position resolution of 400 mum. Energy resolution of 1.8 keV (FWHM: full width at half maximum) was obtained at 59.54 keV. Moreover, the possibility of improved spectral performance by utilizing the energy information of both side strips was demonstrated. We designed and fabricated a new analog ASIC, VA32TA6, for the readout of semiconductor detectors, which is also suitable for DSDs. A new feature of the ASIC is its internal ADC function. We confirmed this function and good noise performance that reaches an equivalent noise charge of 110 e - under the condition of 3-4 pF input capacitance.
During a winter thunderstorm on 6 February 2017 in Japan, photonuclear reactions such as 14N(γ, n)13N were triggered by a downward terrestrial gamma‐ray flash (TGF), as reported by Enoto et al. ...(2017, https://doi.org/10.1038/nature24630). In the present paper, we compare the observation with a simulation model of downward TGFs and subsequent photonuclear reactions constructed by the first paper of the series and Wada, Enoto, Nakazawa, et al. (2019, https://doi.org/10.1103/physrevlett.123.061103). The observation and model consist of three components: annihilation gamma rays from positrons produced by β+‐decay nuclei, deexcitation gamma rays originating from neutron captures, and radiation doses by TGF photons. Each component of the observation is reproduced by the simulation model, and we constrain a relation between the number of avalanche electrons and their production altitude of the downward TGF. The constraints by three components match within an order of magnitude. The downward TGF is estimated to comprise (0.5–2.5) × 1019 avalanche electrons above 1 MeV produced at an altitude of 1.4–2.7 km. Despite differences in altitude, direction, and season, downward TGFs in winter thunderstorms are thought to have the same mechanism of electron acceleration and multiplication in lightning as TGFs observed by in‐orbit satellites.
Plain Language Summary
Lightning flashes are sometimes accompanied by strong high‐energy emission called “terrestrial gamma‐ray flashes” (TGFs). The energy of gamma rays in TGFs is high enough to trigger nuclear reactions with atmospheric nuclei such as nitrogen and oxygen. The nuclear reactions produce neutrons and unstable isotopes that emit positrons. In the companion paper of this series, we calculated the nuclear reactions and propagation processes of their products such as positrons and neutrons and modeled their characteristics at ground level by simulations. In the present paper, the simulation model is compared with the actual observation of a TGF and nuclear reactions during winter thunderstorms in Japan. The model successfully reproduces the observation and estimate the production altitude the number of energetic electrons involved in the TGF.
Key Points
A simulation model of photonuclear reactions in lightning is compared with an observation during a winter thunderstorm reported by Enoto et al. (2017, https://doi.org/10.1038/nature24630)
Three detected signatures originating from positrons, neutrons, and TGF photons are reproduced by the simulation model
A downward TGF triggering photonuclear reactions comprised 1018 to 1019 avalanche electrons produced at 1.4–2.7 km above sea level
Bin mode estimation methods for Compton camera imaging Ikeda, S.; Odaka, H.; Uemura, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2014, Volume:
760
Journal Article
Peer reviewed
We study the image reconstruction problem of a Compton camera which consists of semiconductor detectors. The image reconstruction is formulated as a statistical estimation problem. We employ a ...bin-mode estimation (BME) and extend an existing framework to a Compton camera with multiple scatterers and absorbers. Two estimation algorithms are proposed: an accelerated EM algorithm for the maximum likelihood estimation (MLE) and a modified EM algorithm for the maximum a posteriori (MAP) estimation. Numerical simulations demonstrate the potential of the proposed methods.
Reactive oxygen species are involved in a diversity of biological phenomena such as inflammation, carcinogenesis, aging, and atherosclerosis. We and other investigators have shown that the level of ...8-hydroxy-2'-deoxyguanosine (8-OHdG), a marker for oxidative stress, is increased in either the urine or the mononuclear cells of the blood of type 2 diabetic patients. However, the association between type 2 diabetes and oxidative stress in the pancreatic beta-cells has not been previously described. We measured the levels of 8-OHdG and 4-hydroxy-2-nonenal (HNE)-modified proteins in the pancreatic beta-cells of GK rats, a model of nonobese type 2 diabetes. Quantitative immunohistochemical analyses with specific antibodies revealed higher levels of 8-OHdG and HNE-modified proteins in the pancreatic beta-cells of GK rats than in the control Wistar rats, with the levels increasing proportionally with age and fibrosis of the pancreatic islets. We further investigated whether the levels of 8-OHdG and HNE-modified proteins would be modified in the pancreatic beta-cells of GK rats fed with 30% sucrose solution or 50 ppm of voglibose (alpha-glucosidase inhibitor). In the GK rats, the levels of 8-OHdG and HNE-modified proteins, as well as islet fibrosis, were increased by sucrose treatment but reduced by voglibose treatment. These results indicate that the pancreatic beta-cells of GK rats are oxidatively stressed, and that chronic hyperglycemia might be responsible for the oxidative stress observed in the pancreatic beta-cells.
The Focusing Optics X-ray Solar Imager (FOXSI) is a NASA sounding rocket mission which will study particle acceleration and coronal heating on the Sun through high sensitivity observations in the ...hard X-ray energy band (5-15 keV). Combining high-resolution focusing X-ray optics and fine-pitch imaging sensors, FOXSI will achieve superior sensitivity; two orders of magnitude better than that of the RHESSI satellite. As the focal plane detector, a Double-sided Si Strip Detector (DSSD) with a front-end ASIC (Application Specific Integrated Circuit) will fulfill the scientific requirements of spatial and energy resolution, low energy threshold and time resolution. We have designed and fabricated a DSSD with a thickness of 500 μm and a dimension of 9.6 mm × 9.6 mm, containing 128 strips with a pitch of 75 μm, which corresponds to 8 arcsec at the focal length of 2 m. We also developed a low-noise ASIC specified to FOXSI. The detector was successfully operated in the laboratory at a temperature of -20°C and with an applied bias voltage of 300 V. Extremely good energy resolutions of 430 eV for the p-side and 1.6 keV for the n-side at a 14 keV line were achieved for the detector. We also demonstrated fine-pitch imaging successfully by obtaining a shadow image. Hence the implementation of scientific requirements was confirmed.
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