Natural plutonium from supernovaeThe rapid neutron capture process (r-process) produces many of the heavy chemical elements, but the astrophysical settings where it occurs remain unclear. Leading ...candidates are neutron star mergers and some types of supernovae. Wallner et al. analyzed the plutonium content of a deep-sea crust sample, identifying a few dozen atoms of the r-process isotope plutonium- 244 that were delivered to Earth within the past few million years. There was a simultaneous signal of iron-60, which is known to be produced in supernovae. Comparing the ratios of these isotopes constrains the relative contributions of supernovae and neutron star mergers to r-process nucleosynthesis.Science, this issue p. 742Half of the chemical elements heavier than iron are produced by the rapid neutron capture process (r-process). The sites and yields of this process are disputed, with candidates including some types of supernovae (SNe) and mergers of neutron stars. We search for two isotopic signatures in a sample of Pacific Ocean crust—iron-60 (60Fe) (half-life, 2.6 million years), which is predominantly produced in massive stars and ejected in supernova explosions, and plutonium-244 (244Pu) (half-life, 80.6 million years), which is produced solely in r-process events. We detect two distinct influxes of 60Fe to Earth in the last 10 million years and accompanying lower quantities of 244Pu. The 244Pu/60Fe influx ratios are similar for both events. The 244Pu influx is lower than expected if SNe dominate r-process nucleosynthesis, which implies some contribution from other sources.
•InGaAsSb-based Strain-compensated (SC) MQWs on InP substrates were grown by MOMBE.•XRD, PL, and STEM measurements were used to characterize quality of the SC-MQW.•Thickness modulation was suppressed ...by replacing InGaAs with InGaAsSb as the barrier.•Use of InGaAsSb instead of InGaAs as the well increased the band-gap wavelength.•Absorption coefficient of the SC-MQW was 7000 cm−1 at a wavelength of 2.1 μm.
We report on successful growth on InP substrates of InGaAsSb-based strain-compensated multiquantum-well (SC-MQW) structures with band-gap wavelengths longer than 2 μm. For SC-MQW samples with four quantum wells, the use of InGaAsSb instead of InGaAs as a barrier layer suppressed the thickness modulation significantly, and its use as a well layer increased the photoluminescence peak wavelength by more than 100 nm. The number of wells in the InGaAsSb/InGaAsSb SC-MQW could be increased from 4 to 30 by adjusting the net strain to be 0%. The absorption coefficient of the 30-period SC-MQW sample was approximately 7000 cm−1 at a wavelength of 2.1 μm.
Charge dynamics in a one-dimensional (1D) Mott insulator was investigated by fs pump-probe reflection spectroscopy on an organic charge-transfer compound, ...bis(ethylenedithio)tetrathiafulvalene-difluorotetracyanoquinodimethane (ET-F2TCNQ). The analyses of the transient reflectivity changes demonstrate that low-energy spectral weight induced by photocarrier doping is concentrated on a Drude component being independent of the doping density, and midgap state is never formed. Such phenomena can be explained by the concept of spin-charge separation characteristic of 1D correlated electron systems.
The purpose of this study was to investigate the prognostic value of prognostic nutritional index (PNI) in oral squamous cell carcinoma (OSCC) patients and to undertake a comparative evaluation of ...the prognostic value of comparing PNI, neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and lymphocyte-to-monocyte ratio (LMR) in terms of prognostic utility. A retrospective study was conducted involving 203 consecutive patients with OSCC who were treated with radical surgery with curative intent. The PNI and systemic inflammatory response were developed, and their prognostic utility was evaluated. Kaplan–Meier curve analysis and log-rank testing showed that PNI (P< 0.001), NLR (P=0.011), PLR (P=0.013), and LMR (P=0.014) were significantly associated with overall survival. Multivariate analysis identified PNI as an independent prognostic factor for OSCC patients (P=0.029). In time-dependent receiver operating characteristic curve analysis, PNI was continuously superior to that of NLR, PLR, and LMR. In conclusion, this study suggested that PNI offered an independent prognostic biomarker in OSCC patients undergoing radical surgery. However, this study was small and retrospective, thus further investigations are needed to clarify the utility of PNI for tailor-made treatments in clinical settings.
The authors report buried-heterostructure long-wavelength VCSELs with GaAs/AlGaAs metamorphic DBRs, which has a potential for low thermal resistance and operation in the single transverse mode with a ...large emission area. In spite of their being upside-up and unmounted, they achieve CW operation at 17°C, and VCSELs with a 15-µm mesa exhibit single-mode operation.
Ultrafast photoinduced transitions of a one-dimensional Mott insulator into two distinct electronic phases, metal and charge-density-wave (CDW) state, were achieved in a bromine-bridged Pd-chain ...compound Pd(en)2Br(C5-Y)2H2O (en=ethylenediamine and C5-Y=dialkylsulfosuccinate), by selecting the photon energy of a femtosecond excitation pulse. For the resonant excitation of the Mott-gap transition, excitonic states are generated and converted to one-dimensional CDW domains. For the higher-energy excitation, free electron and hole carriers are produced, giving rise to a transition of the Mott insulator to a metal. Such selectivity in photoconversions by the choice of initial photoexcited states opens a new possibility for the developments of advanced optical switching and memory functions.
Cosmogenic nuclides in tree rings and polar ice cores record the information of past cosmic ray intensities and solar activities. A large 14C increase over 10 years has been discovered around 5480 ...BCE. The 14C variations in this event differ from those of other short‐term cosmic ray events and typical grand solar minima. To elucidate the cause of the 14C increase around 5480 BCE, we measured the 10Be and 36Cl concentrations in the Antarctic Dome Fuji ice core at quasi‐annual and 4–5 years resolutions, respectively. Based on the combined 14C, 10Be, and 36Cl data, the 5480 BCE event was probably not caused by a solar proton event (SPE) or a gamma‐ray event, because the 36Cl concentration did not significantly increase as expected in these events. The incremented 10Be data were enhanced similarly to those of recent grand solar minima, but more rapidly increased (over ∼10 years). These results suggest that an unusual grand solar minimum occurred around 5480 BCE, characterized by a rapidly decreasing solar activity.
Key Points
New high‐resolution 10Be and 36Cl data for the 5480 BCE cosmic ray event were taken from the Antarctic Dome Fuji ice core
Measured 36Cl/10Be ratio was not suitable for either solar proton event or gamma‐ray event origins
The 5480 BCE event might refer to the unusual grand solar minimum which solar activity decreased rapidly in ∼10 years
Clozapine is more effective than other antipsychotics and is the only antipsychotic approved for treatment-resistant schizophrenia. The objective of this study is to reveal the effect of clozapine on ...employment using a bidirectional mirror-image model.
This design was a retrospective observational study that investigated the employment status of patients with treatment-resistant schizophrenia based on medical records. The bidirectional mirror-image model consisted of 1) switching from other antipsychotics to clozapine and 2) switching from clozapine to other antipsychotics. The observation period was 1 year for each pre- and post-clozapine initiation and discontinuation.
We included 36 patients in the bidirectional mirror-image model. The regular employment plus employment support rate was significantly higher in the clozapine phase than in the other antipsychotic phase in the bidirectional mirror-image model (30.6% vs 11.1%,
= 0.039). The days of regular employment plus employment support were also significantly longer in the clozapine phase (61.3 ± 106.2 vs 24.7 ± 82.7 days,
= 0.032). As per the unidirectional mirror-image model, switching to clozapine resulted in significantly higher regular employment plus employment support rates in the clozapine phase than those in the other antipsychotic phase (33.3% vs 10.0%,
= 0.039). Switching from clozapine to other antipsychotics did not exhibit significant differences in any outcomes.
The results suggest that clozapine is superior to other antipsychotics with respect to achieving employment in patients with treatment-resistant schizophrenia. However, biases specific to the mirror-image model need to be considered.
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