1,065 research outputs found
To Duckweeds (\u3cem\u3eLandoltia punctata\u3c/em\u3e), Nanoparticulate Copper Oxide is More Inhibitory than the Soluble Copper in the Bulk Solution
CuO nanoparticles (CuO-NP) were synthesized in a hydrogen diffusion flame. Particle size and morphology were characterized using scanning mobility particle sizing, Brunauer–Emmett–Teller analysis, dynamic light scattering, and transmission electron microscopy. The solubility of CuO-NP varied with both pH and presence of other ions. CuO-NP and comparable doses of soluble Cu were applied to duckweeds, Landoltia punctata. Growth was inhibited 50% by either 0.6 mg L−1 soluble copper or by 1.0 mg L−1 CuO-NP that released only 0.16 mg L−1 soluble Cu into growth medium. A significant decrease of chlorophyll was observed in plants stressed by 1.0 mg L−1 CuO-NP, but not in the comparable 0.2 mg L−1 soluble Cu treatment. The Cu content of fronds exposed to CuO-NP is four times higher than in fronds exposed to an equivalent dose of soluble copper, and this is enough to explain the inhibitory effects on growth and chlorophyll content
L’endocardite à Bartonella en Tunisie: Particularités lésionnelles et évolutives
L'endocardite à Bartonalla est une infection ubiquitaire, son diagnostic est difficile vu qu'il s'agit souvent d'endocardite à hémoculture négative. Lebut de cette étude est d'analyser les particularités lésionnelles et évolutives de cette entité dans un pays du nord d'Afrique, la Tunisie et dedémontrer la gravité de cette infection. Nous avons étudié rétrospectivement les dossiers médicaux de 20 patients atteints d'endocardite à Bartonella, confirmée selon les critères de Dukes modifiés. L'âge moyen de nos patients était 37 ans avec une prédominance masculine (SR=3). Tous nos malades avaient un niveau socio-économique bas. Le motif essentiel de consultation était la dyspnée, 6 patients étaient admis dans un tableau d'insuffisance cardiaque congestive. Une prédilection des lésions au niveau de la valve aortique a été notée (14 cas). Quatorze patients avaient des végétations endocarditiques avec une taille qui dépasse 10 mm chez 8 malades. La majorité des patients (18 patients) présentaient une régurgitation valvulaire massive en rapport principalement avec des mutilations importantes (6 cas de ruptures de cordages mitraux, 2 cas de déchirures des sigmoïdes aortiques, un cas de perforation valvulaire aortique, un cas de désinsertion de prothèse mitrale). Quinze malades (3/4) avaient nécessité une chirurgie à la phase active de la maladie, l'indication majeure était l'insuffisance cardiaque. Une complication neurologique était notée chez 2 malades et une complication rénale chez 3 malades. Treize patients étaient guéris, 5 malades étaient décédés et 2 malades opérés ont présenté une réinfection à staphylococcus aureus et à candida albicans en postopératoire. L'endocardite à Bartonella est une infection grave. Cette Bactérie possède un potentiel destructif important. Le recours à la chirurgie est quasi constant. La morbi-mortalité est élevée. La recherche de cette bactérie devrait être alors systématique chez nos malades suspects d'endocardite d'autant plus que la bartonellose est endémique sur nos terres
Magnetisation studies in Co-Tb / Pt multilayers
We have studied the magnetization in Co86Tb14/Pt multilayers under fields up to 1.8 T and as at room temperature. As the do-Tb layer thickness (tCoTb) decreases below 200 Å the saturation magnetization magnetization (M) increases, the rectangularity of the M-H loops and the coercivity (Hc ) decrease. The effective anisotropy Keff of the multilayers was determined by a torque magnetometer. The product Keff×tCoTb shows a linear dependence with tCoTb as normally found for the superlatices yielding the bulk and surface anisotropies of 106 erg/cm3 and –0.2 erg/cm2 , respectively. These results are explained in terms of an interfacial Co-Pt layer. Keff and Hc are related by the equation Hc = α Keffn/M with the fitting parameters α and n.We have studied the magnetization in Co86Tb14/Pt multilayers under fields up to 1.8 T and as at room temperature. As the do-Tb layer thickness (tCoTb) decreases below 200 Å the saturation magnetization magnetization (M) increases, the rectangularity of the M-H loops and the coercivity (Hc ) decrease. The effective anisotropy Keff of the multilayers was determined by a torque magnetometer. The product Keff×tCoTb shows a linear dependence with tCoTb as normally found for the superlatices yielding the bulk and surface anisotropies of 106 erg/cm3 and –0.2 erg/cm2 , respectively. These results are explained in terms of an interfacial Co-Pt layer. Keff and Hc are related by the equation Hc = α Keffn/M with the fitting parameters α and n
Reliable Self-Deployment of Cloud Applications
International audienceCloud applications consist of a set of interconnected software elements distributed over several virtual machines, themselves hosted on remote physical servers. Most existing solutions for deploying such applications require human intervention to configure parts of the system, do not respect functional dependencies among elements that must be respected when starting them, and do not handle virtual machine failures that can occur when deploying an application. This paper presents a self-deployment protocol that was designed to automatically configure a set of software elements to be deployed on different virtual machines. This protocol works in a decentralized way, i.e., there is no need for a centralized server. It also starts the software elements in a certain order, respecting important architectural invariants. This protocol supports virtual machine and network failures, and always succeeds in deploying an application when faced with a finite number of failures. Designing such highly parallel management protocols is difficult, therefore formal modeling techniques and verification tools were used for validation purposes. The protocol was implemented in Java and was used to deploy industrial applications
Buffer breakdown in GaN-on-Si HEMTs: A comprehensive study based on a sequential growth experiment
Abstract The aim of this work is to investigate the breakdown mechanisms of the layers constituting the vertical buffer of GaN-on-Si HEMTs; in addition, for the first time we demonstrate that the breakdown field of the AlN nucleation layer grown on a silicon substrate is equal to 3.2 MV/cm and evaluate its temperature dependence. To this aim, three samples, obtained by stopping the epitaxial growth of a GaN on Silicon stack at different steps, are studied and compared: Si/AlN, Si/AlN/AlGaN, full vertical stack up to the Carbon doped buffer layer. The current-voltage (IV) characterizations performed at both room temperature and high temperature show that: (i) the defectiveness of the AlN nucleation layer is the root cause of the leakage through an AlN/Silicon junction, and causes the vertical I-V characteristics to have a high device-to-device variability; (ii) the first AlGaN layer grown over the AlN, beside improving the breakdown voltage of the whole structure, causes the leakage current to be more stable and uniform across the sample area; (iii) a thick strain-relief stack and a carbon-doped GaN buffer enhance the breakdown voltage up to more than 750 V at 170 °C, and guarantee a remarkably low device-to-device variability. Furthermore, a set of constant voltage stress on the Si/AlN sample demonstrate that the aluminum nitride layer shows a time dependent breakdown, with Weibull-distributed failures and a shape factor greater than 1, in line with the percolation model
Thromboxane Modulates Endothelial Permeability
The study tests the role of thromboxane in modulating microvascular
permeability in vitro. Cultured monolayers of bovine
aortic endothelial cells were challenged with the thromboxane (Tx)
mimic U46619. This led to disassembly of actin microfilaments, cell
rounding, border retraction and interendotheHal gap formation.
Pretreatment with the Tx receptor antagonist SQ 29,548 prevented the
Tx mimic-induced cytoskeletal changes. The Tx mimic also altered
endothelial cell barrier function. Increased permeability was
indicated by the increased passage of labelled albumin across
monolayers cultured on microcarriers, relative to untreated
endothelial cells (p < 0.05). Furthermore, electron microscopy
of endothelial cells cultured on the basement membrane of human
placental amnion indicated increased permeability based on wide,
interendotheHal gap formation and transit of the tracer horseradish
peroxidase. Quantification of interendothelial gaps revealed an
eleven-fold increase with the Tx mimic relative to untreated
endothial cells (p < 0.05) and prevention by pretreatment with
the Tx receptor antagonist (p < 0.05). These data indicate that
Tx directly modulates the permeability of endothelial cell in
vitro
Secondary ionization of pyrimidine nucleobases and their microhydrated derivatives in helium nanodroplets
Radiation damage in biological systems by ionizing radiation is predominantly
caused by secondary processes such as charge and energy transfer leading to the
breaking of bonds in DNA. Here, we study the fragmentation of cytosine (Cyt)
and thymine (Thy) molecules, clusters and microhydrated derivatives induced by
direct and indirect ionization initiated by extreme-ultraviolet (XUV)
irradiation. Photofragmentation mass spectra and photoelectron spectra of free
Cyt and Thy molecules are compared with mass and electron spectra of Cyt/Thy
clusters and microhydrated Cyt/Thy molecules formed by aggregation in
superfluid helium (He) nanodroplets. Penning ionization after resonant
excitation of the He droplets is generally found to cause less fragmentation
compared to direct photoionization and charge-transfer ionization after
photoionization of the He droplets. When Cyt/Thy molecules and oligomers are
complexed with water molecules, their fragmentation is efficiently suppressed.
However, a similar suppression of fragmentation is observed when homogeneous
Cyt/Thy clusters are formed in He nanodroplets, indicating a general trend.
Penning ionization electron spectra (PIES) of Cyt/Thy are broad and nearly
featureless but PIES of their microhydrated derivatives point at a sequential
ionization process ending in unfragmented microsolvated Cyt/Thy cations.Comment: 9 pages, 8 figure
Traveling waves for nonlinear Schr\"odinger equations with nonzero conditions at infinity, II
We prove the existence of nontrivial finite energy traveling waves for a
large class of nonlinear Schr\"odinger equations with nonzero conditions at
infinity (includindg the Gross-Pitaevskii and the so-called "cubic-quintic"
equations) in space dimension . We show that minimization of the
energy at fixed momentum can be used whenever the associated nonlinear
potential is nonnegative and it gives a set of orbitally stable traveling
waves, while minimization of the action at constant kinetic energy can be used
in all cases. We also explore the relationship between the families of
traveling waves obtained by different methods and we prove a sharp nonexistence
result for traveling waves with small energy.Comment: Final version, accepted for publication in the {\it Archive for
Rational Mechanics and Analysis.} The final publication is available at
Springer via http://dx.doi.org/10.1007/s00205-017-1131-
Representations of sport in the revolutionary socialist press in Britain, 1988–2012
This paper considers how sport presents a dualism to those on the far left of the political spectrum. A long-standing, passionate debate has existed on the contradictory role played by sport, polarised between those who reject it as a bourgeois capitalist plague and those who argue for its reclamation and reformation. A case study is offered of a political party that has consistently used revolutionary Marxism as the basis for its activity and how this party, the largest in Britain, addresses sport in its publications. The study draws on empirical data to illustrate this debate by reporting findings from three socialist publications. When sport did feature it was often in relation to high profile sporting events with a critical tone adopted and typically focused on issues of commodification, exploitation and alienation of athletes and supporters. However, readers’ letters, printed in the same publications, revealed how this interpretation was not universally accepted, thus illustrating the contradictory nature of sport for those on the far left
Order-of-magnitude speedup for steady states and traveling waves via Stokes preconditioning in Channelflow and Openpipeflow
Steady states and traveling waves play a fundamental role in understanding
hydrodynamic problems. Even when unstable, these states provide the
bifurcation-theoretic explanation for the origin of the observed states. In
turbulent wall-bounded shear flows, these states have been hypothesized to be
saddle points organizing the trajectories within a chaotic attractor. These
states must be computed with Newton's method or one of its generalizations,
since time-integration cannot converge to unstable equilibria. The bottleneck
is the solution of linear systems involving the Jacobian of the Navier-Stokes
or Boussinesq equations. Originally such computations were carried out by
constructing and directly inverting the Jacobian, but this is unfeasible for
the matrices arising from three-dimensional hydrodynamic configurations in
large domains. A popular method is to seek states that are invariant under
numerical time integration. Surprisingly, equilibria may also be found by
seeking flows that are invariant under a single very large Backwards-Euler
Forwards-Euler timestep. We show that this method, called Stokes
preconditioning, is 10 to 50 times faster at computing steady states in plane
Couette flow and traveling waves in pipe flow. Moreover, it can be carried out
using Channelflow (by Gibson) and Openpipeflow (by Willis) without any changes
to these popular spectral codes. We explain the convergence rate as a function
of the integration period and Reynolds number by computing the full spectra of
the operators corresponding to the Jacobians of both methods.Comment: in Computational Modelling of Bifurcations and Instabilities in Fluid
Dynamics, ed. Alexander Gelfgat (Springer, 2018
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