Dust Coagulation Regulated by Turbulent Clustering in Protoplanetary Disks

The coagulation of dust particles is a key process in planetesimal formation. However, the radial drift and bouncing barriers are not completely resolved, especially for silicate dust. Since the collision velocities of dust particles are regulated by turbulence in a protoplanetary disk, turbulent clustering should be properly treated. To that end, direct numerical simulations (DNSs) of the Navier–Stokes equations are requisite. In a series of papers, Pan & Padoan used a DNS with Reynolds number Re ~ 1000. Here, we perform DNSs with up to Re = 16,100, which allow us to track the motion of particles with Stokes numbers of 0.01 lesssim St lesssim 0.2 in the inertial range. Through the DNSs, we confirm that the rms relative velocity of particle pairs is smaller by more than a factor of two, compared to that by Ormel & Cuzzi. The distributions of the radial relative velocities are highly non-Gaussian. The results are almost consistent with those by Pan & Padoan or Pan et al. at low Re. Also, we find that the sticking rates for equal-sized particles are much higher than those for different-sized particles. Even in the strong-turbulence case with α-viscosity of 10−2, the sticking rates are as high as gsim50% and the bouncing probabilities are as low as ~10% for equal-sized particles of St lesssim 0.01. Thus, turbulent clustering plays a significant role in the growth of centimeter-sized compact aggregates (pebbles) and also enhances the solid abundance, which may lead to the streaming instability in a disk

Mechanism of cell dissociation with trypsin and EDTA.

The mechanism of cell dissociation with trypsin and EDTA was examined. Cell dissociation was possible when trypsin and EDTA were given simultaneously, when trypsin was given after EDTA treatment, but not when trypsin was given before EDTA treatment.</p

Enhancement of low-frequency spin-orbit-torque ferromagnetic resonance signals by frequency tuning observed in Pt/Py, Pt/Co, and Pt/Fe bilayers

DC voltages via spin rectification effect (SRE), VDC, under microwave irradiation are investigated for three platinum (Pt)/ferromagnetic metal (FM) bilayer structures: Pt/Ni₈₀Fe₂₀, Pt/Co, and Pt/Fe. At the microwave frequency region lower than the resonant frequency, large VDC is obtained at zero DC magnetic field for all devices. In frequency dependence just around the resonant frequency, sharp rise and drop of magnitude in VDC are observed. These behaviors are well explained by the numerically calculated magnetic susceptibility. It is also found that the magnitude of VDC is strongly dependent on the slope of magnetoresistance spectrum. These findings lead to developments of sensitive detection technique for nano-scale magnetization switching

Deletion of Long Isoform of Eukaryotic Elongation Factor 1Bδ Leads to Audiogenic Seizures and Aversive Stimulus-Induced Long-Lasting Activity Suppression in Mice

Alternative splicing enables a gene to give rise to diverse protein products. The Eef1d gene produces two isoforms: a short isoform that encodes translation elongation factor 1Bδ (eEF1Bδ1), and a long isoform that encodes the heat shock-responsive transcription factor eEF1BδL. Previously, we found that eEF1BδL was a splice variant that was specific to the brain and testis, and the protein encoded is thought to have a function in the central nervous system. In this study, we generated knockout (KO) mice of C57BL/6J background that selectively lacked a specific exon in Eef1d for the long isoform. These KO mice lacked eEF1BδL, but not eEF1Bδ1, in the brain. Although the KO mice showed normal anxiety-related and learning behavior in behavioral tests, some showed severe seizures in response to loud sounds (90 dBA), an audiogenic seizures (AGS) response. Furthermore, after the KO mice had been subjected to the fear conditioning test, they showed remarkably decreased locomotor activity in their home cage and in the open-field and elevated plus-maze tests. After the fear conditioning test, a significant decrease in brain weight, atrophy of the hippocampus and midbrain, and reduced cortical layer thickness were observed in the KO mice. We also found a compensatory increase in the eEF1Bδ1 level and elevated protein synthesis with the induction of endoplasmic reticulum stress markers in these mice. Our results suggest that eEF1BδL has an important role in normal brain function especially when exposed to external stimuli

Primary culture of adult rat liver cells. III. Hormonal effects on cytological and biochemical properties of primary cultured cells.

The effect of various hormones on cytological and biochemical properties of cultured hepatic cells were investigated in order to obtain long-term survival of the hepatocytes with adult liver functions in primary culture. Insulin supplementation of the culture medium enhanced the attachemnt efficiency of cells in primary culture without affecting either maintenance of morphological characters of epithelial cells or retention of liver-specific functions in cultured cells. A combination of dexamethasone and insulin was apparently effective in stimulating the formation of a monolayer of polygonal cells with granular cytoplasm and in maintenance of liver-specific functions for relatively longer periods. Supplementation with either dexamethasone or hydrocortisone alone enhanced tyrosine aminotransferase activities in cultured cells for at least 4 days postinoculation. These steroid hormones also allowed growth of small epithelial cells with clear cytoplasm and maintenance of increased albumin production for 8 days after inoculation. The roles of these hormones in the primary culture of isolated hepatic cells are discussed in the present paper.</p

Observation of gigantic spin conversion anisotropy in bismuth

Whilst the g-factor can be anisotropic due to the spin-orbit interaction (SOI), its existence in solids cannot be simply asserted from a band structure, which hinders progress on studies from such the viewpoints. The g-factor in bismuth (Bi) is largely anisotropic; especially for holes at T-point, the g-factor perpendicular to the trigonal axis is negligibly small (< 0.112), whereas the g-factor along the trigonal axis is very large (62.7). We clarified in this work that the large g- factor anisotropy gives rise to the gigantic spin conversion anisotropy in Bi from experimental and theoretical approaches. Spin-torque ferromagnetic resonance was applied to estimate the spin conversion efficiency in rhombohedral (110) Bi to be 17%, which is unlike the negligibly small efficiency in Bi(111). Harmonic Hall measurements supports the large spin conversion efficiency in Bi(110). This is the first observation of gigantic spin conversion anisotropy as the clear manifestation of the g-factor anisotropy. Beyond the emblematic case of Bi, our study unveiled the significance of the g-factor anisotropy in condensed-matter physics and can pave a pathway toward establishing novel spin physics under g-factor control.Comment: 28 pages, 7 figure