1,114 research outputs found
High-frequency antiplane wave propagation in ultra-thin films with nanostructures
AbstractUltrasonic wave propagation is one of powerful and popular methods for measuring mechanical properties of solids even at nano scales. The extraction of material constants from the measured wave data may not be accurate and reliable when waves of short wavelengths are used. The objective of this paper is to study the high-frequency antiplane wave propagation in ultra-thin films at nanoscale. A developed continuum microstructure theory will be used to capture the effect of nanostructures in ultra-thin films. This continuum theory is developed from assumed displacement fields for nanostructures. Local kinematic variables are introduced to express these local displacements and are subjected to internal continuity conditions. The accuracy of the theory is verified by comparing the results with those of the lattice model for the antiplane problem in an infinite elastic medium. Specifically, dispersion curves and corresponding displacement fields for antiplane wave propagation in the ultra-thin films are studied. The inadequacy of the conventional continuum theory is discussed
Stability of 1+1 dimensional causal relativistic viscous hydrodynamics
The stability of the 1+1 dimensional solution of Israel-Stewart theory is
investigated. Firstly, the evolution of the temperature and the ratio of the
bulk pressure over the equilibrium pressure of the background is explored. Then
the stability with linear perturbations is studied by using the Lyapunov direct
method. It shows that the shear viscosity may weaken the instability induced by
the large peak of bulk viscosity around the phase transition temperature .Comment: 18 pages, 4 figures, 1 table; to be published in Nuclear Physics
Heterogeneity of Radial Glia-Like Cells in the Adult Hippocampus.
Adult neurogenesis is tightly regulated by the neurogenic niche. Cellular contacts between niche cells and neural stem cells are hypothesized to regulate stem cell proliferation or lineage choice. However, the structure of adult neural stem cells and the contact they form with niche cells are poorly described. Here, we characterized the morphology of radial glia-like (RGL) cells, their molecular identity, proliferative activity, and fate determination in the adult mouse hippocampus. We found the coexistence of two morphotypes of cells with prototypical morphological characteristics of RGL stem cells: Type α cells, which represented 76% of all RGL cells, displayed a long primary process modestly branching into the molecular layer and type β cells, which represented 24% of all RGL cells, with a shorter radial process highly branching into the outer granule cell layer-inner molecular layer border. Stem cell markers were expressed in type α cells and coexpressed with astrocytic markers in type β cells. Consistently, in vivo lineage tracing indicated that type α cells can give rise to neurons, astrocytes, and type β cells, whereas type β cells do not proliferate. Our results reveal that the adult subgranular zone of the dentate gyrus harbors two functionally different RGL cells, which can be distinguished by simple morphological criteria, supporting a morphofunctional role of their thin cellular processes. Type β cells may represent an intermediate state in the transformation of type α, RGL stem cells, into astrocytes
Calculated phase diagrams, iron tolerance limits, and corrosion of Mg-Al alloys
The factors determining corrosion are reviewed in this paper, with an emphasis on iron tolerance limit and the production of high-purity castings. To understand the iron impurity tolerance limit, magnesium phase diagrams were calculated using the Pandat software package. Calculated phase diagrams can explain the iron tolerance limit and the production of high-purity castings by means of control of melt conditions; this is significant for the production of quality castings from recycled magnesium. Based on the new insight, the influence of the microstructure on corrosion of magnesium alloys is reviewed
Molecular velocity auto-correlation of simple liquids observed by NMR MGSE method
The velocity auto-correlation spectra of simple liquids obtained by the NMR
method of modulated gradient spin echo show features in the low frequency range
up to a few kHz, which can be explained reasonably well by a long
time tail decay only for non-polar liquid toluene, while the spectra of polar
liquids, such as ethanol, water and glycerol, are more congruent with the model
of diffusion of particles temporarily trapped in potential wells created by
their neighbors. As the method provides the spectrum averaged over ensemble of
particle trajectories, the initial non-exponential decay of spin echoes is
attributed to a spatial heterogeneity of molecular motion in a bulk of liquid,
reflected in distribution of the echo decays for short trajectories. While at
longer time intervals, and thus with longer trajectories, heterogeneity is
averaged out, giving rise to a spectrum which is explained as a combination of
molecular self-diffusion and eddy diffusion within the vortexes of hydrodynamic
fluctuations.Comment: 8 pages, 6 figur
The Efficacy, Safety, and Immunogenicity of Switching Between Reference Biopharmaceuticals and Biosimilars: A Systematic Review
To date, no consensus exists among stakeholders about the safety of switching between reference biological products (RPs) and biosimilars, which may have been curbing the implementation of biosimilars in clinical practice. This study synthesizes the available data on switching and assesses whether switching patients from a RP to its biosimilar or vice versa affects efficacy, safety, or immunogenicity outcomes. A total of 178 studies, in which switch outcomes from a RP to a biosimilar were reported, was identified. Data were derived from both randomized controlled trials and real-world evidence. Despite the limitations stemming from a lack of a robust design for most of the studies, the available switching data do not indicate that switching from a RP to a biosimilar is associated with any major efficacy, safety, or immunogenicity issues. Some open-label and observational studies reported increased discontinuation rates after switching, which were mainly attributed to nocebo effects. Involvement of the prescriber in any decision to switch should remain and attention should be paid to the mitigation of a potential nocebo effect
LEEM investigation of the faceting of the Pt covered W(111) surface
A low energy electron microscope (LEEM) has been used to investigate the faceting of W(111) as induced by Pt. The atomically rough W(111) surface, when fully covered with a monolayer film of Pt and annealed to temperatures higher than {approximately} 750 K, experiences a significant morphological restructuring: the initially planar surface undergoes a faceting transition and forms three-sided pyramids with {211} faces. The experiments demonstrate the capability of LEEM for imaging both the fully and partially faceted surface. In addition, we have observed the formation of the facets in real time, when Pt is dosed onto the heated surface. We find that the transition from planar surface, to partially faceted surface, and to fully faceted surface proceeds through the nucleation and growth of spatially separated faceted regions
Natural product proteomining, a quantitative proteomics platform, allows rapid discovery of biosynthetic gene clusters for different classes of natural products
Microbial Biotechnolog
Single-photon events in e^+ e^- collisions
We provide a detailed investigation of single-photon production processes in
collisions with missing momenta carried by neutrinos or neutralinos.
The transition amplitudes for both processes can be organized into a generic
simplified, factorized form; each neutral VA vector current of missing
energy carriers is factorized out and all the characteristics of the reaction
is solely included in the electron vector current. Firstly, we apply the
generic form to give a unified description of a single-photon production with a
Dirac-type or Majorana-type neutrino-pair and to confirm their identical
characteristics as suggested by the so-called Practical Dirac-Majorana
Confusion Theorem. Secondly, we show that the generic amplitude form is
maintained with the anomalous P- and C-invariant WW couplings in the
neutrino-associated process and it enables us to easily understand large
contributions of the anomalous WW couplings at higher energies and, in
particular, at the points away from the Z-resonance peak. Finally, the
neutralino-associated process, which receives modifications in both the
left-handed and right-handed electron currents due to the exchanges of the
left-handed and right-handed selectrons, can be differentiated from the
neutrino-associated ones through the left-right asymmetries and/or the circular
polarization of the outgoing photon.Comment: 20 pages, REVTeX, epsfig.sty, 7 figures (7 eps files
Partial Wave Analysis of
BES data on are presented. The
contribution peaks strongly near threshold. It is fitted with a
broad resonance with mass MeV, width MeV. A broad resonance peaking at 2020 MeV is also required
with width MeV. There is further evidence for a component
peaking at 2.55 GeV. The non- contribution is close to phase
space; it peaks at 2.6 GeV and is very different from .Comment: 15 pages, 6 figures, 1 table, Submitted to PL
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