The evolution of energy in flow driven by rising bubbles

We investigate by direct numerical simulations the flow that rising bubbles cause in an originally quiescent fluid. We employ the Eulerian-Lagrangian method with two-way coupling and periodic boundary conditions. In order to be able to treat up to 288000 bubbles, the following approximations and simplifications had to be introduced: (i) The bubbles were treated as point-particles, thus (ii) disregarding the near-field interactions among them, and (iii) effective force models for the lift and the drag forces were used. In particular, the lift coefficient was assumed to be 1/2, independent of the bubble Reynolds number and the local flow field. The results suggest that large scale motions are generated, owing to an inverse energy cascade from the small to the large scales. However, as the Taylor-Reynolds number is only in the range of 1, the corresponding scaling of the energy spectrum with an exponent of -5/3 cannot develop over a pronounced range. In the long term, the property of local energy transfer, characteristic of real turbulence, is lost and the input of energy equals the viscous dissipation at all scales. Due to the lack of strong vortices the bubbles spread rather uniformly in the flow. The mechanism for uniform spreading is as follows: Rising bubbles induce a velocity field behind them that acts on the following bubbles. Owing to the shear, those bubbles experience a lift force which make them spread to the left or right, thus preventing the formation of vertical bubble clusters and therefore of efficient forcing. Indeed, when the lift is artifically put to zero in the simulations, the flow is forced much more efficiently and a more pronounced energy accumulates at large scales is achieved.Comment: 9 pages, 7 figure

Lateness Gene Concerning Photosensitivity Increases Yield, by Applying Low to High Levels of Fertilization, in Rice, a Preliminary Report

Various genes controlling heading time have been reported in rice. An isogenic-line pair of late and early lines “L” and “E” were developed from progenies of the F1 of Suweon 258 × an isogenic line of IR36 carrying Ur1 gene. The lateness gene for photosensitivity that causes the difference between L and E was tentatively designated as “Ex(t)”, although it's chromosomal location is unknown. The present study was conducted to examine the effects of Ex(t) on yield and related traits in a paddy field in two years. Chemical fertilizers containing N, P2O5 and K2O were applied at the nitrogen levels of 4.00, 9.00 and 18.00 g/m2 in total, being denoted by "N4", "N9" and "N18", respectively, in 2014. L was later in 80%-heading by 18 or 19 days than E. Regarding total brown rice yield (g/m2), L and E were 635 and 577, 606 and 548, and 590 and 501, respectively, at N18, N9 and N4, indicating that Ex(t) increased this trait by 10 to 18%. Ex(t) increased yield of brown rice with thickness above 1.5mm (g/m2), by 9 to 15%. Ex(t) increased spikelet number per panicle by 16 to 22% and spikelet number per m2 by 11 to 18%. Thousand-grain weight (g) was 2 to 4% lower in L than in E. L was not significantly different from E in ripened-grain percentage. Hence, Ex(t) increased yield by increasing spikelet number per panicle. It is suggested that Ex(t) could be utilized to develop high yielding varieties for warmer districts of the temperate zone

Hes6 is required for the neurogenic activity of neurogenin and NeuroD.

In the embryonic neural plate, a subset of precursor cells with neurogenic potential differentiates into neurons. This process of primary neurogenesis requires both the specification of cells for neural differentiation, regulated by Notch signaling, and the activity of neurogenic transcription factors such as neurogenin and NeuroD which drive the program of neural gene expression. Here we study the role of Hes6, a member of the hairy enhancer of split family of transcription factors, in primary neurogenesis in Xenopus embryos. Hes6 is an atypical Hes gene in that it is not regulated by Notch signaling and promotes neural differentiation in mouse cell culture models. We show that depletion of Xenopus Hes6 (Xhes6) by morpholino antisense oligonucleotides results in a failure of neural differentiation, a phenotype rescued by both wild type Xhes6 and a Xhes6 mutant unable to bind DNA. However, an Xhes6 mutant that lacks the ability to bind Groucho/TLE transcriptional co-regulators is only partly able to rescue the phenotype. Further analysis reveals that Xhes6 is essential for the induction of neurons by both neurogenin and NeuroD, acting via at least two distinct mechanisms, the inhibition of antineurogenic Xhairy proteins and by interaction with Groucho/TLE family proteins. We conclude Xhes6 is essential for neurogenesis in vivo, acting via multiple mechanisms to relieve inhibition of proneural transcription factor activity within the neural plate

Long-term efficacy and safety of eculizumab in Japanese patients with generalized myasthenia gravis : a subgroup analysis of the REGAIN open-label extension study

The terminal complement inhibitor eculizumab was shown to improve myasthenia gravis-related symptoms in the 26-week, phase 3, randomized, double-blind, placebo-controlled REGAIN study (NCT01997229). In this 52-week sub-analysis of the open-label extension of REGAIN (NCT02301624), eculizumab's efficacy and safety were assessed in 11 Japanese and 88 Caucasian patients with anti-acetylcholine receptor antibody-positive refractory generalized myasthenia gravis. For patients who had received placebo during REGAIN, treatment with open-label eculizumab resulted in generally similar outcomes in the Japanese and Caucasian populations. Rapid improvements were maintained for 52 weeks, assessed by change in score from open-label extension baseline to week 52 (mean [standard error]) using the following scales (in Japanese and Caucasian patients, respectively): Myasthenia Gravis Activities of Daily Living (-2.4 [1.34] and - 3.3 [0.651); Quantitative Myasthenia Gravis (-2.9 [1.98] and - 4.3 [0.79]); Myasthenia Gravis Composite (-4.5 [2.63] and - 4.9 [1.19]); and Myasthenia Gravis Quality of Life 15-item questionnaire (-8.6 [5.68) and - 6.5 [1.93]). Overall, the safety of eculizumab was consistent with its known safety profile. In this interim sub-analysis, the efficacy and safety of eculizumab in Japanese and Caucasian patients were generally similar, and consistent with the overall REGAIN population

WHAM Observations of H-alpha Emission from High Velocity Clouds in the M, A, and C Complexes

The first observations of the recently completed Wisconsin H-Alpha Mapper (WHAM) facility include a study of emission lines from high velocity clouds in the M, A, and C complexes, with most of the observations on the M I cloud. We present results including clear detections of H-alpha emission from all three complexes with intensities ranging from 0.06 R to 0.20 R. In every observed direction where there is significant high velocity H I gas seen in the 21 cm line we have found associated ionized hydrogen emitting the H-alpha line. The velocities of the H-alpha and 21 cm emission are well correlated in every case except one, but the intensities are not correlated. There is some evidence that the ionized gas producing the H-alpha emission envelopes the 21 cm emitting neutral gas but the H-alpha "halo", if present, is not large. If the H-alpha emission arises from the photoionization of the H I clouds, then the implied Lyman continuum flux F_{LC} at the location of the clouds ranges from 1.3 to 4.2 x 10^5 photons cm^{-2} s^{-1}. If, on the other hand, the ionization is due to a shock arising from the collision of the high-velocity gas with an ambient medium in the halo, then the density of the pre-shocked gas can be constrained. We have also detected the [S II] 6716 angstrom line from the M I cloud and have evidence that the [S II] to H-alpha ratio varies with location on the cloud.Comment: 32 pages, 18 figures, to appear in ApJ (Sept. 10, 1998