Superconductivity is ubiquitous as evidenced by the observation in many crystals including carrier-doped oxides and diamond. Amorphous solids are no exception. However, it remains to be discovered in ...quasicrystals, in which atoms are ordered over long distances but not in a periodically repeating arrangement. Here we report electrical resistivity, magnetization, and specific-heat measurements of Al-Zn-Mg quasicrystal, presenting convincing evidence for the emergence of bulk superconductivity at a very low transition temperature of Formula: see text K. We also find superconductivity in its approximant crystals, structures that are periodic, but that are very similar to quasicrystals. These observations demonstrate that the effective interaction between electrons remains attractive under variation of the atomic arrangement from periodic to quasiperiodic one. The discovery of the superconducting quasicrystal, in which the fractal geometry interplays with superconductivity, opens the door to a new type of superconductivity, fractal superconductivity.
Summary
Using the nationwide health insurance claims database, we found that the age-standardized hip fracture incidence rates in Japan indicated significant increase in males but no significant ...change in females during 2012–2015. The fracture risk in subjects aged 75–84 years indicated decrease in females but no change in males.
Introduction
Nationwide registry data on hip fractures have not yet been established in Japan. Using the newly developed National Database of Health Insurance Claims (NDB), which covers the entire Japanese population, we investigated the incidence rates of hip fractures and the associated regional differences. We also assessed the frequency of osteoporosis prescriptions, bone turnover marker (BTM) level, and bone mineral density (BMD) measurements.
Methods
The annual numbers of hip fractures, osteoporosis prescriptions, and BTM level and BMD measurements by prefecture from 2012 to 2015 were obtained from NDB data. We calculated the standardized claims-data ratio (SCR) in each prefecture.
Results
The age-standardized incidence rates from 2012 to 2015 indicated no significant change in females and significant increase in males (
p
value for trend; 0.920, 0.002, respectively). The fracture risk decreased in females aged 75–84 years and indicated no increase in females aged 85–89 years during 2012–2015, while the fracture risk indicated no change in males aged 75–84 years and increased in males aged 85–89 years. The frequency of osteoporosis prescriptions, BTM level measurements, and BMD measurements in the general population in the corresponding period increased with statistical or marginal significance in females and males. West–east regional differences were observed in the incidence rates; the highest SCR values in the western prefectures were approximately double the lowest values in the eastern prefectures.
Conclusions
The age-standardized hip fracture incidence rates indicated no significant change in females and significant increase in males in Japan from 2012 to 2015.
•This paper reviews the development status of magnetic refrigeration system for hydrogen liquefaction.•FOM of magnetic refrigeration system for hydrogen liquefaction needs to be larger than 0.57 from ...a viewpoint of consuming energy.•A high efficient system with >80% liquefaction efficiency by using the heat pipe.•The AMR systems with the cooling temperature span of 12K for 1.8T of the magnetic field and 6s of the cycle were shown.•Efficiency of magnetic hydrogen liquefaction plant for 10kg/day is estimated to be 0.47 of FOM between 20K and 77K including LN2 work input.
This paper reviews the status of magnetic refrigeration system for hydrogen liquefaction. There is no doubt that hydrogen is one of most important energy sources in the near future. In particular, liquid hydrogen can be utilized for infrastructure construction consisting of storage and transportation. When we compare the consuming energy of hydrogen liquefaction with high pressurized hydrogen gas, FOM must be larger than 0.57 for hydrogen liquefaction. Thus, we need to develop a highly efficient liquefaction method. Magnetic refrigeration using the magneto-caloric effect has potential to realize not only the higher liquefaction efficiency >50%, but also to be environmentally friendly and cost effective. Our hydrogen magnetic refrigeration system consists of Carnot cycle for liquefaction stage and AMR (active magnetic regenerator) cycle for precooling stages. For the Carnot cycle, we develop the high efficient system with >80% liquefaction efficiency by using the heat pipe. For the AMR cycle, we studied two kinds of displacer systems, which transferred the working fluid. We confirmed the AMR effect with the cooling temperature span of 12K for 1.8T of the magnetic field and 6s of the cycle. By using the simulation, we estimate the efficiency of the hydrogen liquefaction plant for 10kg/day. A FOM of 0.47 is obtained for operation temperature between 20K and 77K including LN2 work input.
In this Letter, we report analyses of spatiotemporal dynamics of turbulence and structure in the limit-cycle oscillation (LCO) that precedes an L-to-H transition. Zonal flows are not observed during ...LCO, and the oscillation is the periodic generations or decays of barrier with edge-localized mean flow. Oscillatory Reynolds stress is found to be too small to accelerate the LCO flow, by considering the dielectric constant in magnetized toroidal plasmas. Propagation of changes of the density gradient and turbulence amplitude into the core is also observed.
The turbulent structure formation, where strongly-inhomogeneous turbulence and global electromagnetic fields are self-organized, is a fundamental mechanism that governs the evolution of ...high-temperature plasmas in the universe and laboratory (e.g., the generation of edge transport barrier (ETB) of the H-mode in the toroidal plasmas). The roles of inhomogeneities of radial electric field (Er) are known inevitable. In this mechanism, whether the first derivative of Er (shear) or the second derivative of Er (curvature) works most is decisive in determining the class of nontrivial solutions (which describe the barrier structure). Here we report the experimental identification of the essential role of the Er-curvature on the ETB formation, for the first time, based on the high-spatiotemporal resolution spectroscopic measurement. We found the decisive importance of Er-curvature on ETB formation during ELM-free phase, but there is only a low correlation with the Er-shear value at the peak of normalized ion temperature gradient. Furthermore, in the ELMing phase, the effect of curvature is also quantified in terms of the relationship between pedestal width and thickness of the layer of inhomogeneous Er. This is the fundamental basis to understand the structure of transport barriers in fusion plasmas.
Since 1995, more than 500 exoplanets have been detected using different techniques, of which 12 were detected with gravitational microlensing. Most of these are gravitationally bound to their host ...stars. There is some evidence of free-floating planetary-mass objects in young star-forming regions, but these objects are limited to massive objects of 3 to 15 Jupiter masses with large uncertainties in photometric mass estimates and their abundance. Here, we report the discovery of a population of unbound or distant Jupiter-mass objects, which are almost twice (1.8(+1.7)(-0.8)) as common as main-sequence stars, based on two years of gravitational microlensing survey observations towards the Galactic Bulge. These planetary-mass objects have no host stars that can be detected within about ten astronomical units by gravitational microlensing. However, a comparison with constraints from direct imaging suggests that most of these planetary-mass objects are not bound to any host star. An abrupt change in the mass function at about one Jupiter mass favours the idea that their formation process is different from that of stars and brown dwarfs. They may have formed in proto-planetary disks and subsequently scattered into unbound or very distant orbits.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A peaked ion temperature profile is observed inside the magnetic island during mode locking after the back transition from H mode to L mode in JT-60U. The thermal diffusivity evaluated inside the ...magnetic island is 0.1 m(2)/s, which is much smaller than that outside the magnetic island by an order of magnitude. The present experiment gives clear evidence that ion heat transport inside a magnetic island can bifurcate and the transport level can be suppressed to the very low level associated with the strong flow shear at the boundary.
This paper presents the experimental results of the (Bi,Pb)2Sr2Ca2Cu3O10 (BSCCO) coils impregnated with low-melting point metal, whose melting point is 60°C. The coils were layer-wound without ...turn-to-turn insulation, i.e., no-insulation (NI). We fabricated the coils with polycarbonate bobbin and casing and the coils with aluminum alloy bobbins and casing. The coils with polycarbonate bobbin and casings showed severe degradation after impregnation. The coils with aluminum alloy ones showed less degradation. A long decay time of the magnetic field during a sudden discharge was measured. The decay time was shortened to be 1/39 by an inter-layer insulation with polyimide sheet. Partial insulation, i.e., electrical insulation between adjacent layers, was effective in reducing this long time constant, even for a BSCCO NI coil.
Spatio-temporal structures of ion heat flux and radial electric field are investigated on JT-60U to understand a mechanism of the internal transport barrier (ITB) formation. Contrary to the ...conventional argument that the ITB formation is due to the E×B flow shear suppressions on turbulence, we observe that the E×B shearing rate during the ITB formation is not enough for turbulence suppressions with kρi ∼ 1. Another finding is that the ITB is formed simultaneously with abrupt decreases of ion heat flux in the global region (like the report in Neudatchine et al 1999 Plasma Phys. Control. Fusion 41 L39), and the gradient-flux relations are non-diffusively developed step by step. These observations suggest the importance of the change in the long-radial fluctuations, which is previously observed in JT-60U (Nazikian et al 2005 Phys. Rev. Lett. 94 135002). Therefore, the model of effects by non-uniformity of the radial electric field, under the condition where the scale separation is violated, is employed to explain such fluctuation quenching. Consistent results are obtained showing that the non-uniformity of the radial electric field effectively works on the fluctuations with long-radial wavelength and increases the temperature gradient. It seems natural that the suppression of the long-radial fluctuations drives the global transport improvement to form the ITB.
Abstract
Turbulent transport is undoubtedly important in magnetic confinement plasmas. It has been reported that a lot of transport dynamics are not satisfying the local diffusive models. Here, we ...report the quantitative measurement of electron heat flux associated with ballistic propagating long-range transport events, which is considered to be a component of avalanches. In addition, we show the first observations of the substantial impact of avalanche-driven transport on profile resilience (or profile stiffness) observed in JT-60U. We found that, in the channel of the electron heat flux, the ratio between the increment of the avalanche-driven component to that of the total plasma heating becomes dominant (∼80%) in the case of the high-heating limit. This suggests a possible role for avalanche-driven transport to induce profile resilience, which has been evidenced by flux-driven simulations.
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