Turbulence characteristics of the B\"{o}dewadt layer in a large enclosed rotor-stator system

A three-dimensional (3D) direct numerical simulation is combined with a laboratory study to describe the turbulent flow in an enclosed annular rotor-stator cavity characterized by a large aspect ratio G=(b-a)/h=18.32 and a small radius ratio a/b=0.152, where a and b are the inner and outer radii of the rotating disk and h is the interdisk spacing. The rotation rate Omega under consideration is equivalent to the rotational Reynolds number Re=Omegab2/nu=9.5 x 104, where nu is the kinematic viscosity of the fluid. This corresponds to a value at which an experiment carried out at the laboratory has shown that the stator boundary layer is turbulent, whereas the rotor boundary layer is still laminar. Comparisons of the 3D computed solution with velocity measurements have given good agreement for the mean and turbulent fields. The results enhance evidence of weak turbulence at this Reynolds number, by comparing the turbulence properties with available data in the literature. An approximately self-similar boundary layer behavior is observed along the stator side. The reduction of the structural parameter a1 under the typical value 0.15 and the variation in the wall-normal direction of the different characteristic angles show that this boundary layer is three-dimensional. A quadrant analysis of conditionally averaged velocities is performed to identify the contributions of different events (ejections and sweeps) on the Reynolds shear stress producing vortical structures. The asymmetries observed in the conditionally averaged quadrant analysis are dominated by Reynolds stress-producing events in this B\"{o}dewadt layer. Moreover, case 1 vortices (with a positive wall induced velocity) are found to be the major source of generation of special strong events, in agreement with the conclusions of Lygren and Andersson.Comment: 16 page

Non-LTE line formation for Pr II and Pr III in A and Ap stars

Non-LTE line formation for Pr II and Pr III is considered through a range of effective temperatures between 7250 K and 9500 K. A comprehensive model atom for Pr II/III is based on the measured and the predicted energy levels, in total, 6708 levels of Pr II and Pr III. We describe calculations of the Pr II energy levels and oscillator strengths for the transitions in Pr II and Pr III. The influence of departures from LTE on Pr abundance determinations is evaluated. At Teff >= 8000 K departures from LTE lead to overionization of Pr II and to systematically depleted total absorption in the line and positive abundance corrections. At the lower temperatures, different lines of Pr II may be either weakened or amplified depending on the line strength. The non-LTE effects strengthen the Pr III lines and lead to negative abundance corrections. Non-LTE corrections grow with effective temperature for the Pr II lines, and, in contrast, they decline for the Pr III lines. The Pr II/III model atom is applied to determine the Pr abundance in the atmosphere of the roAp star HD 24712 from the lines of two ionization stages. In the chemically uniform atmosphere with [Pr/H] = 3, the departures from LTE may explain only small part (0.3 dex) of the difference between the LTE abundances derived from the Pr II and Pr III lines (2 dex). We find that the lines of both ionization stages are described for the vertical distribution of the praseodymium where the Pr enriched layer with [Pr/H] > 4 exists in the outer atmosphere at log tau_5000 < -4. The departures from LTE for Pr II/III are strong in the stratified atmosphere and have the opposite sign for the Pr II and Pr III lines. Using the revised partition function of Pr II and experimental transition probabilities, we determine the solar non-LTE abundance of Pr as log (Pr/H) = -11.15\pm0.08.Comment: 17 pages, 4 tables, 11 figures, accepted for publication in A&

The progestin receptor interactome in the female mouse hypothalamus: Interactions with synaptic proteins are isoform specific and ligand dependent

Progestins bind to the progestin receptor (PR) isoforms, PR-A and PR-B, in brain to influence development, female reproduction, anxiety, and stress. Hormone-activated PRs associate with multiple proteins to form functional complexes. In the present study, proteins from female mouse hypothalamus that associate with PR were isolated using affinity pull-down assays with glutathione S-transferase–tagged mouse PR-A and PR-B. Using complementary proteomics approaches, reverse phase protein array (RPPA) and mass spectrometry, we identified hypothalamic proteins that interact with PR in a ligand-dependent and isoform-specific manner and were confirmed by Western blot. Synaptic proteins, including synapsin-I and synapsin-II, interacted with agonist-bound PR isoforms, suggesting that both isoforms function in synaptic plasticity. In further support, synaptogyrin-III and synapsin-III associated with PR-A and PR-B, respectively. PR also interacted with kinases, including c-Src, mTOR, and MAPK1, confirming phosphorylation as an integral process in rapid effects of PR in the brain. Consistent with a role in transcriptional regulation, PR associated with transcription factors and coactivators in a ligand-specific and isoform-dependent manner. Interestingly, both PR isoforms associated with a key regulator of energy homeostasis, FoxO1, suggesting a novel role for PR in energy metabolism. Because many identified proteins in this PR interactome are synaptic proteins, we tested the hypothesis that progestins function in synaptic plasticity. Indeed, progesterone enhanced synaptic density, by increasing synapsin-I–positive synapses, in rat primary cortical neuronal cultures. This novel combination of RPPA and mass spectrometry allowed identification of PR action in synaptic remodeling and energy homeostasis and reveals unique roles for progestins in brain function and disease

Analytical shock solutions at large and small Prandtl number

Exact one-dimensional solutions to the equations of fluid dynamics are derived in the large-Pr and small-Pr limits (where Pr is the Prandtl number). The solutions are analogous to the Pr = 3/4 solution discovered by Becker and analytically capture the profile of shock fronts in ideal gases. The large-Pr solution is very similar to Becker's solution, differing only by a scale factor. The small-Pr solution is qualitatively different, with an embedded isothermal shock occurring above a critical Mach number. Solutions are derived for constant viscosity and conductivity as well as for the case in which conduction is provided by a radiation field. For a completely general density- and temperature-dependent viscosity and conductivity, the system of equations in all three limits can be reduced to quadrature. The maximum error in the analytical solutions when compared to a numerical integration of the finite-Pr equations is O(1/Pr) for large Pr and O(Pr) for small Pr.Comment: 11 pages, 6 figures. Accepted for publication in Journal of Fluid Mechanics Rapid

Genome-wide analyses of cassava Pathogenesis-related (PR) gene families reveal core transcriptome responses to whitefly infestation, salicylic acid and jasmonic acid.

BACKGROUND:Whiteflies are a threat to cassava (Manihot esculenta), an important staple food in many tropical/subtropical regions. Understanding the molecular mechanisms regulating cassava's responses against this pest is crucial for developing control strategies. Pathogenesis-related (PR) protein families are an integral part of plant immunity. With the availability of whole genome sequences, the annotation and expression programs of the full complement of PR genes in an organism can now be achieved. An understanding of the responses of the entire complement of PR genes during biotic stress and to the defense hormones, salicylic acid (SA) and jasmonic acid (JA), is lacking. Here, we analyze the responses of cassava PR genes to whiteflies, SA, JA, and other biotic aggressors. RESULTS:The cassava genome possesses 14 of the 17 plant PR families, with a total of 447 PR genes. A cassava PR gene nomenclature is proposed. Phylogenetic relatedness of cassava PR proteins to each other and to homologs in poplar, rice and Arabidopsis identified cassava-specific PR gene family expansions. The temporal programs of PR gene expression in response to the whitefly (Aleurotrachelus socialis) in four whitefly-susceptible cassava genotypes showed that 167 of the 447 PR genes were regulated after whitefly infestation. While the timing of PR gene expression varied, over 37% of whitefly-regulated PR genes were downregulated in all four genotypes. Notably, whitefly-responsive PR genes were largely coordinately regulated by SA and JA. The analysis of cassava PR gene expression in response to five other biotic stresses revealed a strong positive correlation between whitefly and Xanthomonas axonopodis and Cassava Brown Streak Virus responses and negative correlations between whitefly and Cassava Mosaic Virus responses. Finally, certain associations between PR genes in cassava expansions and response to biotic stresses were observed among PR families. CONCLUSIONS:This study represents the first genome-wide characterization of PR genes in cassava. PR gene responses to six biotic stresses and to SA and JA are demonstrably different to other angiosperms. We propose that our approach could be applied in other species to fully understand PR gene regulation by pathogens, pests and the canonical defense hormones SA and JA

On vv--domains and star operations

Let $\ast$ be a star operation on an integral domain $D$. Let \f(D) be the set of all nonzero finitely generated fractional ideals of $D$. Call $D$ a $\ast$--Pr\"ufer (respectively, $(\ast, v)$--Pr\"ufer) domain if $(FF^{-1})^{\ast}=D$ (respectively, $(F^vF^{-1})^{\ast}=D$) for all F\in \f(D). We establish that $\ast$--Pr\"ufer domains (and $(\ast, v)$--Pr\"ufer domains) for various star operations $\ast$ span a major portion of the known generalizations of Pr\"{u}fer domains inside the class of $v$--domains. We also use Theorem 6.6 of the Larsen and McCarthy book [Multiplicative Theory of Ideals, Academic Press, New York--London, 1971], which gives several equivalent conditions for an integral domain to be a Pr\"ufer domain, as a model, and we show which statements of that theorem on Pr\"ufer domains can be generalized in a natural way and proved for $\ast$--Pr\"ufer domains, and which cannot be. We also show that in a $\ast$--Pr\"ufer domain, each pair of $\ast$-invertible $\ast$-ideals admits a GCD in the set of $\ast$-invertible $\ast$-ideals, obtaining a remarkable generalization of a property holding for the "classical" class of Pr\"ufer $v$--multiplication domains. We also link $D$ being $\ast$--Pr\"ufer (or $(\ast, v)$--Pr\"ufer) with the group Inv$^{\ast}(D)$ of $\ast$-invertible $\ast$-ideals (under $\ast$-multiplication) being lattice-ordered

Nature of the low temperature ordering of Pr in PrBa_2Cu_3O_(6+x)

Theoretical model is presented to describe the anomalous ordered phase of Pr ions in PrBa_2Cu_3O_(6+x) below T_Pr = 12-17 K. The model considers the Pr multipole degrees of freedom and coupling between the Cu and Pr subsystems. We identify the symmetry allowed coupling of Cu and Pr ions and conclude that only an ab-plane Pr dipole ordering can explain the Cu spin rotation observed at T_Pr by neutron diffraction by Boothroyd et al. [A. T. Boothroyd et al., Phys. Rev. Lett. 78, 130 (1997)]. A substantial enhancement of the Pr ordering temperature is shown to arise from the Cu-Pr coupling which is the key for the anomalous magnetic behavior in PrBa_2Cu_3O_(6+x).Comment: 6 pages, 4 figure

Metal-insulator transition and the Pr3+^{3+}/Pr4+^{4+} valence shift in (Pr1−y_{1-y}Yy_{y})0.7_{0.7}Ca0.3_{0.3}CoO3_3

The magnetic, electric and thermal properties of the ($Ln_{1-y}$Y$_{y}$)$_{0.7}$Ca$_{0.3}$CoO$_3$ perovskites ($Ln$~=~Pr, Nd) were investigated down to very low temperatures. The main attention was given to a peculiar metal-insulator transition, which is observed in the praseodymium based samples with $y=0.075$ and 0.15 at $T_{M-I}=64$ and 132~K, respectively. The study suggests that the transition, reported originally in Pr$_{0.5}$Ca$_{0.5}$CoO$_3$, is not due to a mere change of cobalt ions from the intermediate- to the low-spin states, but is associated also with a significant electron transfer between Pr$^{3+}$ and Co$^{3+}$/Co$^{4+}$ sites, so that the praseodymium ions occur below $T_{M-I}$ in a mixed Pr$^{3+}$/Pr$^{4+}$ valence. The presence of Pr$^{4+}$ ions in the insulating phase of the yttrium doped samples (Pr$_{1-y}$Y$_{y}$)$_{0.7}$Ca$_{0.3}$CoO$_3$ is evidenced by Schottky peak originating in Zeeman splitting of the ground state Kramers doublet. The peak is absent in pure Pr$_{0.7}$Ca$_{0.3}$CoO$_3$ in which metallic phase, based solely on non-Kramers Pr$^{3+}$ ions, is retained down to the lowest temperature.Comment: 10 figure