Mapping supernovae to their progenitors is fundamental to understanding the collapse of massive stars. We investigate the red supergiant problem, which concerns why red supergiants with masses ∼16–30 ...M⊙ have not been identified as progenitors of Type IIP supernovae, and the supernova rate problem, which concerns why the observed cosmic supernova rate is smaller than the observed cosmic star formation rate. We find key physics to solving these in the compactness parameter, which characterizes the density structure of the progenitor. If massive stars with compactness above ξ2.5 ∼ 0.2 fail to produce canonical supernovae, (i) stars in the mass range 16–30 M⊙ populate an island of stars that have high ξ2.5 and do not produce canonical supernovae, and (ii) the fraction of such stars is consistent with the missing fraction of supernovae relative to star formation. We support this scenario with a series of two- and three-dimensional radiation hydrodynamics core-collapse simulations. Using more than 300 progenitors covering initial masses 10.8–75 M⊙ and three initial metallicities, we show that high compactness is conducive to failed explosions. We then argue that a critical compactness of ∼0.2 as the divide between successful and failed explosions is consistent with state-of-the-art three-dimensional core-collapse simulations. Our study implies that numerical simulations of core collapse need not produce robust explosions in a significant fraction of compact massive star initial conditions.
Abstract
Coalescence of multiple magnetic islands is recognized as an effective process to energize particles during magnetic reconnection, while its energy conversion process still remains unclear. ...Here, a two-dimensional fully kinetic simulation of multiple island coalescence with a small reconnection guide field is studied. In the analysis of energy conversion within a magnetic island, the dot product of
V
e
·
j
×
B
=
w
1
is a useful quantity to compare with
j
·
E
=
w
2
, since the average work done by the Lorentz force on the circulating particles is negligible in the island and
w
2
−
w
1
=
j
·
E
+
V
e
×
B
=
j
·
E
′
=
w
3
. A bipolar pattern of
w
1
is found at a secondary island when the electrons are in circular motion inside the island. Significant energy dynamo (
w
3
< 0) resulting from
j
∥
E
∥
is found at the secondary island, which has not been reported before, where the parallel electric field
E
∥
is highly correlated with
w
3
. Moreover, significant energy dissipation (
w
3
> 0) due to
j
⊥
·
E
⊥
′
is seen in the merging region between two coalescing islands. Both types of energy conversions are accompanied by enhancements in
j
∥
and the parallel electron temperature
T
e
∥
. Three ion-scale magnetic islands (FR1, FR2, and FR3) observed by the Magnetospheric Multiscale spacecraft are compared favorably with the simulated signatures of energy dynamo and dissipation of an evolving secondary island. In particular, FR1 displayed a similar energy dynamo signature as that simulated in an early stage of the secondary island. FR2 and FR3 showed a dominant
j
⊥
·
E
⊥
′
energy conversion similar to that obtained in a later stage of the secondary island.
Gemcitabine plus cisplatin (GC) is the standard treatment of advanced biliary tract cancer (BTC); however, it causes nausea, vomiting, and anorexia, and requires hydration. Gemcitabine plus S-1 (GS) ...reportedly has equal to, or better, efficacy and an acceptable toxicity profile. We aimed to confirm the non-inferiority of GS to GC for patients with advanced/recurrent BTC in terms of overall survival (OS).
We undertook a phase III randomized trial in 33 institutions in Japan. Eligibility criteria included chemotherapy-naïve patients with recurrent or unresectable BTC, an Eastern Cooperative Oncology Group Performance Status of 0−1, and adequate organ function. The calculated sample size was 350 with a one-sided α of 5%, a power of 80%, and non-inferiority margin hazard ratio (HR) of 1.155. The primary end point was OS, while the secondary end points included progression-free survival (PFS), response rate (RR), adverse events (AEs), and clinically significant AEs defined as grade ≥2 fatigue, anorexia, nausea, vomiting, oral mucositis, or diarrhea.
Between May 2013 and March 2016, 354 patients were enrolled. GS was found to be non-inferior to GC median OS: 13.4months with GC and 15.1months with GS, HR, 0.945; 90% confidence interval (CI), 0.78–1.15; P=0.046 for non-inferiority. The median PFS was 5.8months with GC and 6.8months with GS (HR 0.86; 95% CI 0.70–1.07). The RR was 32.4% with GC and 29.8% with GS. Both treatments were generally well-tolerated. Clinically significant AEs were observed in 35.1% of patients in the GC arm and 29.9% in the GS arm.
GS, which does not require hydration, should be considered a new, convenient standard of care option for patients with advanced/recurrent BTC.
This trial has been registered with the UMIN Clinical Trials Registry (http://www.umin.ac.jp/ctr/index.htm), number UMIN000010667.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
We have developed a dedicated front-end electronics board for a high-pressure xenon gas time projection chamber for a neutrinoless double-beta decay search. The ionization signal is read out by ...detecting electroluminescence photons with silicon photomultipliers (SiPMs). The board reads out the signal from 56 SiPMs and records the waveforms at 5 MS/s with a wide dynamic range up to 4000 photons/200 ns. The SiPM bias voltages are provided by the board. Fine adjustment of the bias voltage for each channel is realized while keeping the dc coupling readout constant, which is indispensable for readout of microsecond-long pulses or at high rate environment. Additional analog-to-digital converters (ADCs) measure one photon-equivalent dark current for calibration and monitoring of the SiPM. The obtained performance satisfies the requirement for a neutrinoless double-beta decay search.
We investigate the accuracy with which the reconnection electric field EM can be determined from in situ plasma data. We study the magnetotail electron diffusion region observed by National ...Aeronautics and Space Administration's Magnetospheric Multiscale (MMS) on 11 July 2017 at 22:34 UT and focus on the very large errors in EM that result from errors in an LMN boundary normal coordinate system. We determine several LMN coordinates for this MMS event using several different methods. We use these M axes to estimate EM. We find some consensus that the reconnection rate was roughly EM = 3.2 ± 0.6 mV/m, which corresponds to a normalized reconnection rate of 0.18 ± 0.035. Minimum variance analysis of the electron velocity (MVA‐ve), MVA of E, minimization of Faraday residue, and an adjusted version of the maximum directional derivative of the magnetic field (MDD‐B) technique all produce reasonably similar coordinate axes. We use virtual MMS data from a particle‐in‐cell simulation of this event to estimate the errors in the coordinate axes and reconnection rate associated with MVA‐ve and MDD‐B. The L and M directions are most reliably determined by MVA‐ve when the spacecraft observes a clear electron jet reversal. When the magnetic field data have errors as small as 0.5% of the background field strength, the M direction obtained by MDD‐B technique may be off by as much as 35°. The normal direction is most accurately obtained by MDD‐B. Overall, we find that these techniques were able to identify EM from the virtual data within error bars ≥20%.
Key Points
The reconnection rate EM is estimated for one event using several techniques to find an M direction
The error bars in EM and the LMN coordinate directions are estimated from virtual data
The reconnection rate is likely EM = 3.2 mV/m ± 0.6 mV/m, which corresponds to a normalized rate of 0.18 ± 0.035
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
We present an improved search for neutrinoless double-beta (0νββ) 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 0νββ 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.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
Vasopressin has many physiological actions in addition to its well‐defined role in the control of fluid homeostasis and urine concentration. An increasing body of evidence suggests that the ...vasopressin–hydration axis plays a role in glucose homeostasis. This review summarizes the knowledge accumulated over the last decades about the influence of vasopressin in the short‐term regulation of glycaemia. It describes the possible role of this hormone through activation of V1a and V1b receptors on liver and pancreas functions and on the hypothalamic–pituitary–adrenal axis. Moreover, we report recent in vivo studies demonstrating the role of vasopressin in the long‐term regulation of glycaemia. Indeed, V1a‐ or double‐V1aV1b‐receptor knockout mice display significant changes in the glucose and lipid metabolism. In rats, sustained high V1aR activation increases basal glycaemia and aggravates glucose intolerance in obese rats. Finally, the translation from animal findings to human was evidenced by epidemiological and genetic studies that showed that high vasopressin level is a risk factor for hyperglycaemia, metabolic disorders and diabetes.
Content List ‐ Read more articles from the symposium: “Vasopressin: novel roles for an old hormone. Emerging therapies in cardiometabolic and renal diseases”.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Abstract
At the Earth's magnetopause, the Kelvin‐Helmholtz (KH) instability, driven by the persistent velocity shear between the magnetosheath and the magnetosphere, has been frequently observed ...during northward interplanetary magnetic field periods and considered as one of the most important candidates for transporting and mixing plasmas across the magnetopause. However, how this process interacts with magnetic field fluctuations, which persistently exist near the magnetopause, has been less discussed. Here we perform a series of 2‐D fully kinetic simulations of the KH instability at the magnetopause considering a power law spectrum of initial fluctuations in the magnetic field. The simulations demonstrate that when the amplitude level of the initial fluctuations is sufficiently large, the KH instability evolves faster, leading to a more efficient plasma mixing within the vortex layer. In addition, when the spectral index of the initial fluctuations is sufficiently small, the modes whose wavelength is longer than the theoretical fastest growing mode grow dominantly. The fluctuating magnetic field also results in the formation of the well‐matured turbulent spectrum with a −5/3 index within the vortex layer even in the early nonlinear growth phase of the KH instability. The obtained spectral features in the simulations are in reasonable agreement with the features in KH waves events at the magnetopause observed by the Magnetospheric Multiscale mission and conjunctively by the Geotail and Cluster spacecraft. These results indicate that the magnetic field fluctuations may really contribute to enhancing the wave activities especially for longer wavelength modes and the associated mixing at the magnetopause.
Key Points
The 2‐D fully kinetic simulations of magnetopause Kelvin‐Helmholtz instability initially imposing power law field fluctuations are performed
The growth of the instability especially for long wavelength modes is enhanced by the fluctuating field, leading to more efficient mixing
Spectral features obtained from the simulations are in reasonable agreement with past spacecraft observations at the Earth's magnetopause
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Summary
In a 4-year follow-up study that enrolled 1099 subjects aged ≥60 years, sarcopenia prevalence was estimated at 8.2%. Moreover, the presence of osteoporosis was significantly associated with ...short-term sarcopenia occurrence, but the reciprocal relationship was not observed, suggesting that osteoporosis would increase the risk of osteoporotic fracture and sarcopenia occurrence.
Introduction
The present 4-year follow-up study was performed to clarify the prevalence, incidence, and relationships between sarcopenia (SP) and osteoporosis (OP) in older Japanese men and women.
Methods
We enrolled 1099 participants (aged, ≥60 years; 377 men) from the second survey of the Research on Osteoarthritis/Osteoporosis against Disability (ROAD) study (2008–2010) and followed them up for 4 years. Handgrip strength, gait speed, skeletal muscle mass, and bone mineral density were assessed. SP was defined according to the Asian Working Group for Sarcopenia. OP was defined based on the World Health Organization criteria.
Results
SP prevalence was 8.2% (men, 8.5%; women, 8.0%) in the second survey. In those with SP, 57.8% (21.9%; 77.6%) had OP at the lumbar spine L2–4 and/or femoral neck. SP cumulative incidence was 2.0%/year (2.2%/year; 1.9%/year). Multivariate regression analysis revealed that OP was significantly associated with SP occurrence within 4 years (odds ratio, 2.99; 95% confidence interval, 1.46–6.12;
p
< 0.01), but the reciprocal relationship was not significantly observed (2.11; 0.59–7.59;
p
= 0.25).
Conclusions
OP might raise the short-term risk of SP incidence. Therefore, OP would not only increase the risk for osteoporotic fracture but may also increase the risk for SP occurrence.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Summary Objectives The purposes of this study were to investigate the prevalence and distribution of intervertebral disc degeneration (DD) over the entire spine using magnetic resonance imaging ...(MRI), and to examine the factors and symptoms potentially associated with DD. Design This study included 975 participants (324 men, mean age of 67.2 years; 651 women, mean age of 66.0 years) with an age range of 21–97 years in the Wakayama Spine Study. DD on MRI was classified into Pfirrmann's system (grades 4 and 5 indicating DD). We assessed the prevalence of DD at each level in the cervical, thoracic, and lumbar regions and the entire spine, and examined DD-associated factors and symptoms. Results The prevalence of DD over the entire spine was 71% in men and 77% in women aged <50 years, and >90% in both men and women aged >50 years. The prevalence of an intervertebral space with DD was highest at C5/6 (men: 51.5%, women: 46%), T6/7 (men: 32.4%, women: 37.7%), and L4/5 (men: 69.1%, women: 75.8%). Age and obesity were associated with the presence of DD in all regions. Low back pain was associated with the presence of DD in the lumbar region. Conclusion The current study established the baseline data of DD over the entire spine in a large population of elderly individuals. These data provide the foundation for elucidating the causes and mechanisms of DD.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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