414 research outputs found
The Initial mass function of the first stars inferred from extremely metal-poor stars
This is an author-created, un-copyedited version of an article published in The Astrophysical Journal. The Version of Record is available online at https://doi.org/10.3847/1538-4357/aab3de.We compare the elemental abundance patterns of ~200 extremely metal-poor (EMP; [Fe/H] < −3) stars to the supernova yields of metal-free stars, in order to obtain insights into the characteristic masses of the first (Population III or Pop III) stars in the universe. The supernova yields are prepared with nucleosynthesis calculations of metal-free stars with various initial masses (M = 13, 15, 25, 40 and 100 M ⊙) and explosion energies (E 51 = E/1051[erg] = 0.5–60), to include low-energy, normal-energy, and high-energy explosions. We adopt the mixing-fallback model, to take into account possible asymmetry in the supernova explosions, and the yields that best fit the observed abundance patterns of the EMP stars are searched by varying the model parameters. We find that the abundance patterns of the EMP stars are predominantly best-fitted by the supernova yields with initial masses M < 40 M ⊙, and that more than than half of the stars are best-fitted by the M = 25 M ⊙ hypernova (E 51 = 10) models. The results also indicate that the majority of the primordial supernovae have ejected 10−2–10−1 M ⊙ of 56Ni, leaving behind a compact remnant (either a neutron star or a black hole), with a mass in the range of ~1.5–5 M ⊙. These results suggest that the masses of the first stars responsible for the first metal enrichment are predominantly <40 M ⊙. This implies that the higher-mass first stars were either less abundant, directly collapsed into a black hole without ejecting heavy elements, or a supernova explosion of a higher-mass first star inhibits the formation of the next generation of low-mass stars at [Fe/H] < −3.Peer reviewedFinal Accepted Versio
Origin of the anomalous mass renormalization in metallic quantum well states of correlated oxide SrVO
angle-resolved photoemission spectroscopy (ARPES) has been
performed on SrVO ultrathin films, which show metallic quantum well (QW)
states, to unveil the origin of the anomalous mass enhancement in the QW
subbands. The line-shape analysis of the ARPES spectra reveals that the
strength of the electron correlation increases as the subband bottom energy
approaches the Fermi level. These results indicate that the anomalous
subband-dependent mass enhancement mainly arises from the quasi-one-dimensional
character of confined V states as a result of their orbital-selective
quantization.Comment: 6 pages, 3 figure
Emergence of quantum critical behavior in metallic quantum-well states of strongly correlated oxides
Controlling quantum critical phenomena in strongly correlated electron
systems, which emerge in the neighborhood of a quantum phase transition, is a
major challenge in modern condensed matter physics. Quantum critical phenomena
are generated from the delicate balance between long-range order and its
quantum fluctuation. So far, the nature of quantum phase transitions has been
investigated by changing a limited number of external parameters such as
pressure and magnetic field. We propose a new approach for investigating
quantum criticality by changing the strength of quantum fluctuation that is
controlled by the dimensional crossover in metallic quantum well (QW)
structures of strongly correlated oxides. With reducing layer thickness to the
critical thickness of metal-insulator transition, crossover from a Fermi liquid
to a non-Fermi liquid has clearly been observed in the metallic QW of SrVO
by \textit{in situ} angle-resolved photoemission spectroscopy. Non-Fermi liquid
behavior with the critical exponent is found to emerge in the
two-dimensional limit of the metallic QW states, indicating that a quantum
critical point exists in the neighborhood of the thickness-dependent Mott
transition. These results suggest that artificial QW structures provide a
unique platform for investigating novel quantum phenomena in strongly
correlated oxides in a controllable fashion.Comment: 6 pages, 3 figure
Machine learning detects multiplicity of the first stars in stellar archaeology data
In unveiling the nature of the first stars, the main astronomical clue is the
elemental compositions of the second generation of stars, observed as extremely
metal-poor (EMP) stars, in our Milky Way Galaxy. However, no observational
constraint was available on their multiplicity, which is crucial for
understanding early phases of galaxy formation. We develop a new data-driven
method to classify observed EMP stars into mono- or multi-enriched stars with
Support Vector Machines. We also use our own nucleosynthesis yields of
core-collapse supernovae with mixing-fallback that can explain many of observed
EMP stars. Our method predicts, for the first time, that of
462 analyzed EMP stars are classified as mono-enriched. This means that the
majority of EMP stars are likely multi-enriched, suggesting that the first
stars were born in small clusters. Lower metallicity stars are more likely to
be enriched by a single supernova, most of which have high carbon enhancement.
We also find that Fe, Mg. Ca, and C are the most informative elements for this
classification. In addition, oxygen is very informative despite its low
observability. Our data-driven method sheds a new light on solving the mystery
of the first stars from the complex data set of Galactic archaeology surveys.Comment: Accepted by ApJ, main results in Fig. 5, source code is available at
https://gitlab.com/thartwig/emu-
MEASUREMENT OF ANTIOXIDANT POWER OF MOUTHWASHES INDICATED IN STOMATITIS
ABSTRACTObjective: Hospital formulations containing allopurinol and rebamipide are used in the prophylactic and therapeutic management of stomatitis,owing to their antioxidant powers. The objective of this study was to measure the antioxidant powers of Zyloric® tablets (allopurinol), Mucosta®tablets (rebamipide), different hospital formulations indicated in the management of stomatitis (allopurinol and rebamipide mouthwashes), andAzulene® 0.4% for Gargle (sodium azulene sulfonate).Methods: We measured the antioxidant powers of Zyloric® and Mucosta® tablets, all hospital formulations indicated in the management of stomatitis(allopurinol and rebamipide mouthwashes), and the widely used Azulene® 0.4% for Gargle by employing the biological antioxidant potential test. Wecompared the efficacy of each of these drugs in the management of stomatitis.Results: Azulene® 0.4% for Gargle was found to have stronger antioxidant power than Zyloric® (100 mg) and Mucosta® (100 mg) tablets dissolved inwater. The antioxidant power of the solvent used in hospital formulations was similar to that of the prepared hospital formulation. Antioxidant powerof the drugs themselves was not observed in both the allopurinol and rebamipide mouthwashes.Conclusion: The antioxidant power of the drugs was not observed in both the allopurinol and rebamipide mouthwashes; therefore, hospitalformulations used as antioxidants were found to be less effective in the treatment of stomatitis. However, Azulene® 0.4% for Gargle was found to beuseful in the prophylactic and therapeutic management of stomatitis, owing to its antioxidant, and anti-inflammatory effects.Keywords: Stomatitis, Bone alkaline phosphatase-test, Allopurinol mouthwash, Rebamipide mouthwash, Azulene® 0.4% for Gargle, Antioxidant powe
Quantum computing quantum Monte Carlo with hybrid tensor network toward electronic structure calculations of large-scale molecular and solid systems
Quantum computers are expected to solve the problems for quantum chemistry
and materials science with higher accuracy than classical computers. Quantum
computing quantum Monte Carlo (QC-QMC) is a method that can be combined with
quantum algorithms such as variational quantum eigensolver (VQE) to obtain the
ground state with fewer quantum resources and higher accuracy than either VQE
or QMC alone. In this study, we propose an algorithm combining QC-QMC with
hybrid tensor network (HTN) to extend the applicability of QC-QMC for the
system beyond the size of a single quantum device, and we named the algorithm
HTN+QMC. For HTN with the structure of a two-layer quantum-quantum tree tensor,
the proposed algorithm for an -qubit reference wave function (trial
wave function) in QMC can be performed by using only a -qubit device
excluding ancilla qubits. Full configuration interaction QMC is adopted as an
example of QMC, and the proposed algorithm is applied to the Heisenberg chain
model, the graphite-based Hubbard model, the hydrogen plane model, and
MonoArylBiImidazole (MABI). The results show that the algorithm can achieve
energy accuracy several orders of magnitude higher than either VQE or QMC
alone. In addition, the energy accuracy of HTN+QMC is as same as QC-QMC when
the system is appropriately decomposed. These results pave the way to
electronic structure calculation for large systems with high accuracy on
current quantum devices.Comment: 27pages, 19 figures, 5 table
Balance Measures Derived from Insole Sensor Differentiate Prodromal Dementia with Lewy Bodies
Dementia with Lewy bodies is the second most common type of neurodegenerative
dementia, and identification at the prodromal stagei.e., mild cognitive
impairment due to Lewy bodies (MCI-LB)is important for providing appropriate
care. However, MCI-LB is often underrecognized because of its diversity in
clinical manifestations and similarities with other conditions such as mild
cognitive impairment due to Alzheimer's disease (MCI-AD). In this study, we
propose a machine learning-based automatic pipeline that helps identify MCI-LB
by exploiting balance measures acquired with an insole sensor during a 30-s
standing task. An experiment with 98 participants (14 MCI-LB, 38 MCI-AD, 46
cognitively normal) showed that the resultant models could discriminate MCI-LB
from the other groups with up to 78.0% accuracy (AUC: 0.681), which was 6.8%
better than the accuracy of a reference model based on demographic and clinical
neuropsychological measures. Our findings may open up a new approach for timely
identification of MCI-LB, enabling better care for patients
Mapping of panda plumage color locus on the microsatellite linkage map of the Japanese quail
BACKGROUND: Panda (s) is an autosomal recessive mutation, which displays overall white plumage color with spots of wild-type plumage in the Japanese quail (Coturnix japonica). In a previous study, the s locus was included in the same linkage group as serum albumin (Alb) and vitamin-D binding protein (GC) which are mapped on chicken (Gallus gallus) chromosome 4 (GGA4). In this study, we mapped the s locus on the microsatellite linkage map of the Japanese quail by linkage analysis. RESULTS: Segregation data on the s locus were obtained from three-generation families (n = 106). Two microsatellite markers derived from the Japanese quail chromosome 4 (CJA04) and three microsatellite markers derived from GGA4 were genotyped in the three-generation families. We mapped the s locus between GUJ0026 and ABR0544 on CJA04. By comparative mapping with chicken, this locus was mapped between 10.0 Mb and 14.5 Mb region on GGA4. In this region, the endothelin receptor B subtype 2 gene (EDNRB2), an avian-specific paralog of the mammalian endothelin receptor B gene (EDNRB), is located. Because EDNRB is responsible for aganglionic megacolon and spot coat color in mouse, rat and equine, EDNRB2 is suggested to be a candidate gene for the s locus. CONCLUSION: The s locus and the five microsatellite markers were mapped on CJA04 of the Japanese quail. EDNRB2 was suggested to be a candidate gene for the s locus
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