748 research outputs found
Machine learning with systematic density-functional theory calculations: Application to melting temperatures of single and binary component solids
A combination of systematic density functional theory (DFT) calculations and
machine learning techniques has a wide range of potential applications. This
study presents an application of the combination of systematic DFT calculations
and regression techniques to the prediction of the melting temperature for
single and binary compounds. Here we adopt the ordinary least-squares
regression (OLSR), partial least-squares regression (PLSR), support vector
regression (SVR) and Gaussian process regression (GPR). Among the four kinds of
regression techniques, the SVR provides the best prediction. In addition, the
inclusion of physical properties computed by the DFT calculation to a set of
predictor variables makes the prediction better. Finally, a simulation to find
the highest melting temperature toward the efficient materials design using
kriging is demonstrated. The kriging design finds the compound with the highest
melting temperature much faster than random designs. This result may stimulate
the application of kriging to efficient materials design for a broad range of
applications
Multi-messenger signals of long-term core-collapse supernova simulations : synergetic observation strategies
The next Galactic supernova is expected to bring great opportunities for the
direct detection of gravitational waves (GW), full flavor neutrinos, and
multi-wavelength photons. To maximize the science return from such a rare
event, it is essential to have established classes of possible situations and
preparations for appropriate observations. To this end, we use a long-term
numerical simulation of the core-collapse supernova (CCSN) of a 17 solar-mass
red supergiant progenitor to self-consistently model the multi-messenger
signals expected in GW, neutrino, and electromagnetic messengers. This
supernova model takes into account the formation and evolution of a
protoneutron star, neutrino-matter interaction, and neutrino transport, all
within a two-dimensional shock hydrodynamics simulation. With this, we
separately discuss three situations: (i) a CCSN at the Galactic Center, (ii) an
extremely nearby CCSN within hundreds of parsecs, and (iii) a CCSN in nearby
galaxies within several Mpc. These distance regimes necessitate different
strategies for synergistic observations. In a Galactic CCSN, neutrinos provide
strategic timing and pointing information. We explore how these in turn deliver
an improvement in the sensitivity of GW analyses and help to guarantee
observations of early electromagnetic signals. To facilitate the detection of
multi-messenger signals of CCSNe in extremely nearby and extragalactic
distances, we compile a list of nearby red supergiant candidates and a list of
nearby galaxies with their expected CCSN rates. By exploring the sequential
multi-messenger signals of a nearby CCSN, we discuss preparations for
maximizing successful studies of such an unprecedented stirring event.Comment: Link to the online material (lists of nearby RSG candidates and local
galaxies) is added, also available from
http://th.nao.ac.jp/MEMBER/nakamura/2016multi/index.htm
Effects of gelation concentration on cyclic deformation behavior of κ-carrageenan hydrogels
The aim of this study is to elucidate the relationship between the network structure of κ-carrageenan hydrogels and their mechanical properties. First κ-carrageenan hydrogels have been prepared at different gelation concentrations, and then the mechanical behavior during four cyclic deformations has been examined at the same κ-carrageenan concentration. Young's modulus is higher for the gel prepared at 5 gL⁻¹ (C05) compared to that for the gel prepared at 30 gL⁻¹ (C30). C30 shows almost linear relation between the stress and the strain like an ideal rubber, while a residual strain appears in each cyclic deformation for C05. The extent of the residual strain depends on the maximum strain and the deformation speed, indicating that C05 deforms plastically to some extent. The residual strain for C05 decreases gradually even after a cyclic deformation and disappears in the case of a small strain as if there were a memory of the structure. The effects of the gelation concentration on the mechanical properties have been explained based on the network structure specific to κ-carrageenan hydrogels. The higher modulus for C05 has been attributed to the higher helix content and the plastic deformation of C05 to the loosely-aggregated crosslinks
Beneficial Xultophy Treatment from Medical and Social Points of View
The case is a 65-year-old male who has been treated for Type 2 diabetes mellitus (T2DM) for 26 years. He has no previous history of cerebral vascular accident (CVA) or coronary heart disease (CHD). He has been treated on insulin therapy, and recently his glucose variability became worse due to the irregular lifestyle. Then, diabetic treatment was changed to Xultophy, which consists of insulin degludec and liraglutide. Providing 16 units of Xultophy brought him a satisfactory daily profile of blood glucose, which seemed to be lower doses compared with the ordinary standard amount. Treatment of Xultophy seems to be effective and some discussion would be described from several points of view
Study on acoustical physical constants of ZnO single crystal using the ultrasonic microspectroscopy technology
2008 IEEE International Ultrasonics Symposium Proceeding
Pre-DECIGO can get the smoking gun to decide the astrophysical or cosmological origin of GW150914-like binary black holes
Pre-DECIGO consists of three spacecraft arranged in an equilateral triangle
with 100km arm lengths orbiting 2000km above the surface of the earth. It is
hoped that the launch date will be in the late 2020s.
Pre-DECIGO has one clear target: binary black holes (BBHs) like GW150914 and
GW151226. Pre-DECIGO can detect BBH mergers up to
redshift . The cumulative event rate is in the Pop III origin model of BBHs like GW150914, and it
saturates at , while in the primordial BBH (PBBH) model, the
cumulative event rate is at
even if only of the dark matter consists of PBHs, and it is
still increasing at . In the Pop I/II model of BBHs, the cumulative event
rate is and it saturates at . We present the requirements on orbit accuracy, drag free techniques, laser
power, frequency stability, and interferometer test mass. For BBHs like
GW150914 at 1Gpc, SNR is achieved with the definition of Pre-DECIGO in
the Hz band. Pre-DECIGO can measure the mass spectrum and the
-dependence of the merger rate to distinguish various models of BBHs like
GW150914.
Pre-DECIGO can also predict the direction of BBHs at with an accuracy
of and a merging time accuracy of s at about a
day before the merger so that ground-based GW detectors further developed at
that time as well as electromagnetic follow-up observations can prepare for the
detection of merger in advance. For intermediate mass BBHs at a large redshift
, the QNM frequency after the merger can be within the Pre-DECIGO band
so that the ringing tail can also be detectable to confirm the Einstein theory
of general relativity with SNR.
[abridged]Comment: 17 pages, 10 figures, added some references, modifications to match
the published version in PTE
Intermediate-Mass-Elements in Young Supernova Remnants Reveal Neutron Star Kicks by Asymmetric Explosions
The birth properties of neutron stars yield important information on the
still debated physical processes that trigger the explosion and on intrinsic
neutron-star physics. These properties include the high space velocities of
young neutron stars with average values of several 100 km/s, whose underlying
"kick" mechanism is not finally clarified. There are two competing
possibilities that could accelerate NSs during their birth: anisotropic
ejection of either stellar debris or neutrinos. We here present new evidence
from X-ray measurements that chemical elements between silicon and calcium in
six young gaseous supernova remnants are preferentially expelled opposite to
the direction of neutron star motion. There is no correlation between the kick
velocities and magnetic field strengths of these neutron stars. Our results
support a hydrodynamic origin of neutron-star kicks connected to asymmetric
explosive mass ejection, and they conflict with neutron-star acceleration
scenarios that invoke anisotropic neutrino emission caused by particle and
nuclear physics in combination with very strong neutron-star magnetic fields.Comment: 24 pages, 12 figures, accepted for publication in The Astrophysical
Journa
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