•Wakefield acceleration of charged particles in the jets from an accreting blackhole.•Nearby starburst and Seyfert galaxies can accelerate protons to 1020 eV or above.•Three hot spot in the sky is ...predicted by the wakefield acceleration theory.•They also emit high energy gamma-rays from the electrons accelerated by the wakefield.
We consider that electromagnetic pulses produced in the jets of the innermost part of the accretion disk accelerate charged particles (protons, ions, electrons) to very high energies including energies above 1020 eV for the case of protons and nucleus and 1012-15 eV for electrons by electromagnetic wave-particle interaction. The episodic eruptive accretion in the disk by the magneto-rotational instability gives rise to strong electro-magnetic pulses, which act as the driver of the collective accelerating ponderomotive force. The accelerated hadrons (protons and nuclei) are released to the intergalactic space to be ultra-high energy cosmic rays. Some of them collide with the protons in the interstellar medium to produce secondary particles, such as neutrinos and gamma-ray photons. The high-energy electrons, on the other hand, emit photons in the collisions with electromagnetic disturbances to produce various non-thermal emissions (radio, IR, visible, UV, and gamma-rays) of active galactic nuclei. Applying the bow wakefield acceleration theory to eight galaxies (M82, NGC0253, NGC4945, NGC1068, NGC6814, Cen A, M87, and For A), we find two starburst galaxies (M82 and NGC0253), one Seyfert galaxy (NGC4945), and one radio galaxy (Cen A) are promising as UHECR (Ultra-High Energy Cosmic-ray) sources and can form hot spots around them. The sky map of these four galaxies is consistent to the arrival direction analysis of the UHECRs. In particular, M82 seams responsible to form the northern hot spot suggested by TA group.
Water transport must be efficiency controlled for the future sustainability of life. Various water transport systems using carbon nanotubes have been proposed in recent years. Although these systems ...are more permeable than aquaporins, their water transport is passive. In this study, we successfully demonstrate an active water pump driven by simple hydrophobic interaction through computer simulation. Even in the absence of a pressure- or density-gradient, the proposed pump can actively transport water molecules by alternately switching the hydrophobicity of the pump surface. The water transport rate can be easily controlled by varying the time interval of switching. The pump with optimized switching time exhibits prominent water permeance. The results obtained herein can be applied in various water transport technologies because of the simple mechanics. The proposed water pump has the potential to realize an effective device such as a low-energy artificial purification system.
The Earth was born as a dry planet without atmosphere and ocean components at 4.56 Ga,with subsequent secondary accretion of bio-elements,such as carbon（C）,hydrogen（H）,oxygen（O）,and nitrogen（N） which ...peaked at 4.37-4.20 Ga.This two-step formation model of the Earth we refer to as the advent of bio-elements model（ABEL Model） and the event of the advent of bio-elements（water component） as ABEL Bombardment.It is clear that the solid Earth originated from enstatite chondrite-like dry material based on the similarity in oxygen isotopic composition and among other isotopes.On the other hand,Earth＇s water derives primarily from carbonaceous chondrite material based on the hydrogen isotopic ratio.We present our ABEL model to explain this enigma between solid Earth and water,as well as secondary accretion of oxidizing bio-elements,which became a precursor to initiate metabolism to emerge life on a highly reductive planet.If ABEL Bombardment had not occurred,life never would have emerged on the Earth.Therefore,ABEL Bombardment is one of the most important events for this planet to evolve into a habitable planet.The chronology of ABEL Bombardment is informed through previous researches of the late heavy bombardment and the late veneer model.ABEL Bombardment is considered to have occurred during 4.37-4.20 Ga,which is the concept to redefine the standard late heavy bombardment and the late veneer models.Also,ABEL Bombardment is the trigger of the transition from stagnant lid tectonics to plate tectonics on this planet because of the injection of volatiles into the initial dry Earth.
Water droplets on rugged hydrophobic surfaces typically exhibit one of the following two states: (i) the Wenzel state Wenzel RN (1936) Ind Eng Chem 28:988-994 in which water droplets are in full ...contact with the rugged surface (referred as the wetted contact) or (ii) the Cassie state Cassie, ABD, Baxter S (1944) Trans Faraday Soc 40:546-551 in which water droplets are in contact with peaks of the rugged surface as well as the "air pockets" trapped between surface grooves (the composite contact). Here, we show large-scale molecular dynamics simulation of transition between Wenzel state and Cassie state of water droplets on a periodic nanopillared hydrophobic surface. Physical conditions that can strongly affect the transition include the height of nanopillars, the spacing between pillars, the intrinsic contact angle, and the impinging velocity of water nanodroplet ("raining" simulation). There exists a critical pillar height beyond which water droplets on the pillared surface can be either in the Wenzel state or in the Cassie state, depending on their initial location. The free-energy barrier separating the Wenzel and Cassie state was computed on the basis of a statistical-mechanics method and kinetic raining simulation. The barrier ranges from a few tenths of kBT₀ (where kB is the Boltzmann constant, and T₀ is the ambient temperature) for a rugged surface at the critical pillar height to almost equal to8 kBT₀ for the surface with pillar height greater than the length scale of water droplets. For a highly rugged surface, the barrier from the Wenzel-to-Cassie state is much higher than from Cassie-to-Wenzel state. Hence, once a droplet is trapped deeply inside the grooves, it would be much harder to relocate on top of high pillars.
•Alfven wave bursts emitted from accretion disk around a blackhole accelerate particles to ZeV.•The acceleration is collinear to the particle motion and does not suffer from the radiation ...loss.•Accelerated protons/nuclei become ultra high energy cosmic rays beyond 1020eV.•The system also accelerates electrons to emit gamma-rays in above 100GeV.•The theory explains the natures of gamma-ray and variability of blazars.
An accreting supermassive blackhole, the central engine of active galactic nucleus (AGN), is capable of exciting extreme amplitude Alfven waves whose wavelength (wave packet) size is characterized by its clumpiness. The pondermotive force and wakefield are driven by these Alfven waves propagating in the AGN (blazar) jet, and accelerate protons/nuclei to extreme energies beyond Zetta-electron volt (ZeV=1021eV). Such acceleration is prompt, localized, and does not suffer from the multiple scattering/bending enveloped in the Fermi acceleration that causes excessive synchrotron radiation loss beyond 1019eV. The production rate of ZeV cosmic rays is found to be consistent with the observed gamma-ray luminosity function of blazars and their time variabilities.
Abstract
Summary
: Similarity searches of amino acid sequences against the public metagenomic data can provide users insights about the function of sequences based on the environmental distribution ...of similar sequences. However, a considerable reduction in the amount of data or the accuracy of the result was necessary to conduct sequence similarity searches against public metagenomic data, because of the vast data size more than Terabytes. Here, we present an ultra-fast service for the highly accurate amino acid sequence similarity search, called PZLAST, which can search the user’s amino acid sequences to several Terabytes of public metagenomic sequences in ∼10–20 min. PZLAST accomplishes its search speed by using PEZY-SC2, which is a Multiple Instruction Multiple Data many-core processor. Results of PZLAST are summarized by the ontology-based environmental distribution of similar sequences. PZLAST can be used to predict the function of sequences and mine for homologs of functionally important gene sequences.
Availability and implementation
PZLAST is freely accessible at https://pzlast.riken.jp/meta without requiring registration.
Supplementary information
Supplementary data are available at Bioinformatics online.
The cerebellum is a part of the brain that plays essential roles in real-time motor learning and control and even cognitive functions. Thanks to the large amount of anatomical and physiological data, ...we implemented a spiking network model of the cerebellum on Shoubu, an energy-efficient supercomputer with 1280 PEZY-SC processors at RIKEN. Our artificial cerebellum consists of more than one billion neurons, which is comparable to the whole cerebellum of a cat. Using 1008 of 1280 processors on Shoubu, we achieved real-time simulation, that is, a computer simulation of the model for 1 s completes within 1 s of the real world with temporal resolution of 1 ms. Effective performance was estimated as 68 teraflops in single-precision floating points, suggesting 2.6% of peak performance. We expect that the artificial cerebellum will be applicable to various engineering applications, such as robotics and brain-style artificial intelligence.
•The new framework of planet formation for solar system.•Magneto-rotational instability (MRI) and porous aggregation are included.•Planets are formed at the outer and inner boundaries of the MRI ...suppressed region.•Icy planetesimals are formed at the outer boundary through gravitational Instability.•Rocky particles are accumulated at the inner boundary to form terrestrial planets.
The present paper is the first one of a series of papers that present the new united theory of planet formation, which includes magneto-rotational instability and porous aggregation of solid particles in an consistent way. We here describe the “tandem” planet formation regime, in which a solar system like planetary systems are likely to be produced.
We have obtained a steady-state, 1-D model of the accretion disk of a protostar taking into account the magneto-rotational instability (MRI) and and porous aggregation of solid particles. We find that the disk is divided into an outer turbulent region (OTR), a MRI suppressed region (MSR), and an inner turbulent region (ITR). The outer turbulent region is fully turbulent because of MRI. However, in the range, rout(=8−60 AU) from the central star, MRI is suppressed around the midplane of the gas disk and a quiet area without turbulence appears, because the degree of ionization of gas becomes low enough. The disk becomes fully turbulent again in the range rin(=0.2−1 AU), which is called the inner turbulent region, because the midplane temperature become high enough (>1000 K) due to gravitational energy release.
Planetesimals are formed through gravitational instability at the outer and inner MRI fronts (the boundaries between the MRI suppressed region (MSR) and the outer and inner turbuent regions) without particle enhancement in the original nebula composition, because of the radial concentration of the solid particles. At the outer MRI front, icy particles grow through low-velocity collisions into porous aggregates with low densities (down to ∼10−5gcm−3). They eventually undergo gravitational instability to form icy planetesimals.
On the other hand, rocky particles accumulate at the inner MRI front, since their drift velocities turn outward due to the local maximum in gas pressure. They undergo gravitational instability in a sub-disk of pebbles to form rocky planetesimals at the inner MRI front. They are likely to be volatile-free because of the high temperature (>1000 K) at this formation site. Such water-free rocky particles may explain the formation of enstatite chondrites, of which the Earth is likely to be primarily composed of. It is also consistent with the model in which the Earth was initially formed as a completely volatile-free planet. The water and other volatile elements came later through the accretion of icy particles by the occasional scatterings in the outer regions.
Our new proposed tandem planet formation regime shows that planetesimals are formed at two distinct sites (outer and inner edges of the MRI suppressed region). The former is likely to be the source of outer gas giants and the latter inner rocky planets. The tandem regime also explains the gap in the distribution of solid components (2–4 AU), which is necessary to form a “solar-system-like” planetary system, which has a relatively small Mars and a very small mass in the main asteroid belt.
We found that this tandem regime dose not take place when the vertical magnetic field of the disk five times weaker compared with that we assumed in the present paper, since the outer MRI front shift outward beyond 100 AU. This suggests that yet other regimes exists in our united theory. It may explain the variation observed in exsoplanetary systems by variations in magnetic field and probably angular momentum of the parent molecular cloud.
In recent years, many plans have arisen for building constellations in low Earth orbit, some of which have already provided commercial services. The number of satellites that form these ...constellations will exceed
10
4
, and a number of these could become space debris due to accidental failure, leading to serious problems for human activities in space. Laser ablation-induced propulsion achieved by remote irradiation from the service spacecraft has been proposed as one effective method to remove such space debris and it involves effectively generating a propulsion impulse from a laser. Because most of the high-power lasers currently utilized in space applications are Nd:YAG lasers, in this study, we evaluate the characteristics of second harmonic generation (SHG), which can be generated using nonlinear crystals. The momentum coupling coefficient may be dependent on the irradiated laser wave length which has a significant difference in the ablation process such as plasma generation and heating. These effects have been investigated using an impulse measurement instrumental setup with a KD*P nonlinear crystal. As an efficient impulse generation method, the irradiation of the fundamental and SHG beams of the Nd:YAG laser at the same point was found to be more effective than the fundamental beam with the same total energy. SHG does not require additional power-consuming equipment such as additional exciters or amplifiers, but requite temperature-controlled nonlinear crystals, and impulses can be increased with minimal additional power. It turned out to be advantageous for space applications, which will require minimum power operation . Additionally, we found an additional nonlinear laser-induced impulses through the interaction of the beams.
We have followed the evolution of multimass star clusters containing massive central black holes through collisional N-body simulations done on GRAPE6. Each cluster is composed of between 16,384 and ...131,072 stars together with a black hole with an initial mass of M sub(BH) = 1000 M sub( ). We follow the evolution of the clusters under the combined influence of two-body relaxation, stellar mass loss, and tidal disruption of stars by the massive central black hole. We find that the (three-dimensional) mass density profile follows a power-law distribution r 6 r super(-a) with slope a = 1.55 inside the sphere of influence of the central black hole. This leads to a constant-density profile of bright stars in projection, which makes it highly unlikely that core-collapse clusters contain intermediate-mass black holes (IMBHs). Instead, globular clusters containing massive central black holes can be fitted with standard King profiles. Because of energy generation in the cusp, star clusters with IMBHs expand. The cluster expansion is so strong that clusters that start very concentrated can end up among the least dense clusters. The amount of mass segregation in the core is also smaller compared to postcollapse clusters without IMBHs. Most stellar mass black holes with masses M sub(BH) > 5 M sub( )are lost from the clusters within a few gigayears through mutual encounters in the cusp around the IMBH. Black holes in star clusters disrupt mainly main-sequence stars and giants and no neutron stars. The disruption rates are too small to form an IMBH out of a M sub(BH) - 50 M sub( )progenitor black hole even if all material from disrupted stars is accreted onto the black hole, unless star clusters start with central densities significantly higher than what is seen in present-day globular clusters. We also discuss the possible detection mechanisms for IMBHs. Our simulations show that kinematical studies can reveal 1000 M sub( )IMBHs in the closest clusters. IMBHs in globular clusters are weak X-ray sources, since the tidal disruption rate of stars is low and the star closest to the IMBH is normally another black hole, which prevents other stars from undergoing stable mass transfer. For globular clusters, dynamical evolution can push compact stars near the IMBH to distances small enough that they become detectable sources of gravitational radiation. If 10% of all globular clusters contain IMBHs, extragalactic globular clusters could be one of the major sources of gravitational wave events for LISA.
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