3,669 research outputs found
Non-barotropic linear Rossby wave instability in three-dimensional disks
Astrophysical disks with localized radial structure, such as protoplanetary
disks containing dead zones or gaps due to disk-planet interaction, may be
subject to the non-axisymmetric Rossby wave instability (RWI) that lead to
vortex-formation. The linear instability has recently been demonstrated in
three-dimensional (3D) barotropic disks. It is the purpose of this study to
generalize the 3D linear problem to include an energy equation, thereby
accounting for baroclinity in three-dimensions. Linear stability calculations
are presented for radially structured, vertically stratified,
geometrically-thin disks with non-uniform entropy distribution in both
directions. Polytropic equilibria are considered but adiabatic perturbations
assumed. The unperturbed disk has a localized radial density bump making it
susceptible to the RWI. The linearized fluid equations are solved numerically
as a partial differential equation eigenvalue problem. Emphasis on the ease of
method implementation is given. It is found that when the polytropic index is
fixed and adiabatic index increased, non-uniform entropy has negligible effect
on the RWI growth rate, but pressure and density perturbation magnitudes near a
pressure enhancement increases away from the midplane. The associated
meridional flow is also qualitatively changed from homentropic calculations.
Meridional vortical motion is identified in the nonhomentropic linear solution,
as well as in a nonlinear global hydrodynamic simulation of the RWI in an
initially isothermal disk evolved adiabatically. Numerical results suggest
buoyancy forces play an important role in the internal flow of Rossby vortices.Comment: 16 pages, accepted by ApJ, substantial re-writes for improved
clarity, extended results analysi
Photochemical Characterization of a New Heliorhodopsin from the Gram-Negative Eubacterium Bellilinea caldifistulae (BcHeR) and Comparison with Heliorhodopsin-48C12
Many microorganisms express rhodopsins, pigmented membrane proteins capable of absorbing sunlight and harnessing that energy for important biological functions such as ATP synthesis and phototaxis. Microbial rhodopsins that have been discovered to date are categorized as type-1 rhodopsins. Interestingly, researchers have very recently unveiled a new microbial rhodopsin family named the heliorhodopsins, which are phylogenetically distant from type-1 rhodopsins. Among them, only heliorhodopsin-48C12 (HeR-48C12) from a Gram-positive eubacterium has been photochemically characterized [Pushkarev, A., et al. (2018) Nature 558, 595-599]. In this study, we photochemically characterize a purple-colored heliorhodopsin from Gram-negative eubacterium Bellilinea caldifistulae (BcHeR) as a second example and identify which properties are or are not conserved between BcHeR and HeR-48C12. A series of photochemical measurements revealed several conserved properties between them, including a visible absorption spectrum with a maximum at around 550 nm, the lack of ion-transport activity, and the existence of a second-order O-like intermediate during the photocycle that may activate an unidentified biological function. In contrast, as a property that is not conserved, although HeR-48C12 shows the light adaptation state of retinal, BcHeR showed the same retinal configuration under both dark- and light-adapted conditions. These comparisons of photochemical properties between BcHeR and HeR-48C12 are an important first step toward understanding the nature and functional role of heliorhodopsins
Behaviours of Bubbles in the Gas-Solid Fluidized-Beds
The size, shape and rising velocity of bubbles and also particle concentration in bubbles which appeared in the air-solid fluidized bed were investigated by photography, X-ray photograpy, X-ray cinematography and capacitance method. The results were that the bubbles had nearly the shape of spherical cap and there were few particles in the bubbles. Although the rising velocity of the bubble was affected largely by other bubbles, it was proportional to the square root of the vertical bubble length and the bubbles became large with the process of repetition of coalescence and redispersion
Pd-catalysed, Ag-assisted C2-H alkenylation of benzophospholes
A palladium-catalysed, silver-assisted regioselective C2-H alkenylation of benzophospholes with terminal alkenes has been developed. The palladium catalysis accommodates styrenes and electron-deficient alkenes including ester, ketone, nitrile, and phosphonate. Thus, this protocol enables the rapid construction of various benzophosphole-vinylene conjugations from the two simple C-H starting substrates. Optical properties of newly synthesized C2-alkenylated benzophospholes are also investigated.Tokura Y., Xu S., Kojima Y., et al. Pd-catalysed, Ag-assisted C2-H alkenylation of benzophospholes. Chemical Communications 58, 12208 (2022); https://doi.org/10.1039/D2CC04942B
Existence of two-channel Kondo regime for tunneling impurities with resonant scattering
Dynamical tunneling systems have been proposed earlier to display a
two-channel Kondo effect, the orbital index of the particle playing the role of
a pseudospin in the equivalent Kondo problem, and the spin being a silent
channel index. However, as shown recently by Aleiner et al. [Phys. Rev. Lett.
86, 2629 (2001)], the predicted two-channel Kondo behavior can never be
observed in the weak coupling regime, where the tunneling induced splitting of
the levels of the tunneling system always dominates the physics. Here we show
that the above scenario changes completely if the conduction electrons are
scattered by resonant scattering off the tunneling impurity; Then - as a
non-perturbative analysis reveals - the two-channel Kondo regime can easily be
reached.Comment: 10 PRB page
New Types of Specialists in Higher Education : From the Viewpoint of Policy, Market and Occupational Ability
高等教育改革において新しい役割を担う「専門職」の必要が生じている。本論ではそのうち,ファカルティ・ディベロッパー(FDer),キャリア支援担当者,インスティテューショナル・リサーチ(IR)担当者,リサーチ・アドミニストレーション(URA)担当者,産官学連携コーディネート担当者を取り上げる。これらの「専門職」は養成の制度化がいまだに不十分であって,他の隣接分野からの移動という事例も見られる。また,雇用のための予算が改革を推進するための時限付きの補助金であることが多いため,雇用期限が定められていたり,職位・給与が低位であったりするという特徴がある。The current higher education reforms in Japan have created a demand for new types of specialists who have had important roles in most universities since around 2000. This article focuses on Faculty Developers, Career Consultants, Institutional Researchers, University Research Administrators and Technology Licensing Managers among such new types of university-related jobs. Due to the lack of formal education systems to become one of these professionals, most of the candidates do not have enough knowledge and skills, and tend to come from related academic or business areas. When they are hired by universities, funds for their employment often come from government money budgeted for a time-limited and specific educational reform project. As a result, they tend to be hired for only a limited period of time, and/or their position and wage levels are usually lower than more traditional professions in universities
Morphology and melt rheology of nylon 11/clay nanocomposites
Nylon 11 (PA11)/clay nanocomposites have been prepared by melt-blending, followed by melt-extrusion through a capillary. Transmission electron microscopy shows that the exfoliated clay morphology is dominant for low nanofiller content, while the intercalated one is prevailing for high filler loading. Melt rheological properties of PA11 nanocomposites have been studied in both linear and nonlinear viscoelastic response regions. In the linear regime, the nanocomposites exhibit much higher storage modulus (G') and loss modulus (G'') values than neat PA11. The values of G' and G'' increase steadily with clay loading at low concentrations, while the G' and G'' for the sample with 5 wt % clay show an inverse dependence and lie between the modulus values of the samples with 1 and 2 wt % of clay. This is attributed to the alignment/orientation of nanoclay platelets in the intercalated nanocomposite induced by capillary extrusion. In the nonlinear regime, the nanocomposites show increased shear viscosities when compared with the neat resin. The dependence of the shear viscosity on clay loading has analogous trend to that of G' and G''. Finally, a comparison has been made between the complex and steady viscosities to verify the applicability of the empirical Cox-Merz rule
Small molecule induced reactivation of mutant p53 in cancer cells
The p53 cancer mutant Y220C is an excellent paradigm for rescuing the function of conformationally unstable p53 mutants because it has a unique surface crevice that can be targeted by small-molecule stabilizers. Here, we have identified a compound, PK7088, which is active in vitro: PK7088 bound to the mutant with a dissociation constant of 140 μM and raised its melting temperature, and we have determined the binding mode of a close structural analogue by X-ray crystallography. We showed that PK7088 is biologically active in cancer cells carrying the Y220C mutant by a battery of tests. PK7088 increased the amount of folded mutant protein with wild-type conformation, as monitored by immunofluorescence, and restored its transcriptional functions. It induced p53-Y220C-dependent growth inhibition, cell-cycle arrest and apoptosis. Most notably, PK7088 increased the expression levels of p21 and the proapoptotic NOXA protein. PK7088 worked synergistically with Nutlin-3 on up-regulating p21 expression, whereas Nutlin-3 on its own had no effect, consistent with its mechanism of action. PK7088 also restored non-transcriptional apoptotic functions of p53 by triggering nuclear export of BAX to the mitochondria. We suggest a set of criteria for assigning activation of p53
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