1,215 research outputs found
Fine structure of the absorption cross-section of gases in the ultraviolet and an analysis of the ray system of the lunar crater tycho scientific report no. 3, sep. 1963 - apr. 1964
Fine structure of absorption cross-section of gases in ultraviolet and analysis of ray system of lunar crater Tych
Global axisymmetric Magnetorotational Instability with density gradients
We examine global incompressible axisymmetric perturbations of a
differentially rotating MHD plasma with radial density gradients. It is shown
that the standard magnetorotational instability, (MRI) criterion drawn from the
local dispersion relation is often misleading. If the equilibrium magnetic
field is either purely axial or purely toroidal, the problem reduces to finding
the global radial eigenvalues of an effective potential. The standard Keplerian
profile including the origin is mathematically ill-posed, and thus any solution
will depend strongly on the inner boundary. We find a class of unstable modes
localized by the form of the rotation and density profiles, with reduced
dependence on boundary conditions.Comment: 22 pages, 5 figure
Numerical study of Yang-Mills classical solutions on the twisted torus
We use the lattice cooling method to investigate the structure of some gauge
fixed SU(2) Yang-Mills classical solutions of the euclidean equations of motion
which are defined in the 3-torus with symmetric twisted boundary conditions.Comment: 20pp (fig.included
The Expected Perimeter in Eden and Related Growth Processes
Following Richardson and using results of Kesten on First-passage
percolation, we obtain an upper bound on the expected perimeter in an Eden
Growth Process. Using results of the author from a problem in Statistical
Mechanics, we show that the average perimeter of the lattice animals resulting
from a very natural family of "growth histories" does not obey a similar bound.Comment: 11 page
Matrix metalloproteinase-19 inhibits growth of endothelial cells by generating angiostatin-like fragments from plasminogen
<p>Abstract</p> <p>Background</p> <p>Angiogenesis is the process of forming new blood vessels from existing ones and requires degradation of the vascular basement membrane and remodeling of extracellular matrix (ECM) in order to allow endothelial cells to migrate and invade into the surrounding tissue. Matrix metalloproteinases (MMPs) are considered to play a central role in the remodeling of basement membranes and ECM. However, MMPs contribute to vascular remodeling not only by degrading ECM components. Specific MMPs enhance angiogenesis via several ways; they help pericytes to detach from vessels undergoing angiogenesis, release ECM-bound angiogenic growth factors, expose cryptic pro-angiogenic integrin binding sites in the ECM, generate promigratory ECM component fragments, and cleave endothelial cell-cell adhesions. MMPs can also negatively influence the angiogenic process through generating endogenous angiogenesis inhibitors by proteolytic cleavage. Angiostatin, a proteolytic fragment of plasminogen, is one of the most potent antagonists of angiogenesis that inhibits migration and proliferation of endothelial cells. Reports have shown that metalloelastase, pancreas elastase, plasmin reductase, and plasmin convert plasminogen to angiostatin.</p> <p>Results</p> <p>We report here that MMP-19 processes human plasminogen in a characteristic cleavage pattern to generate three angiostatin-like fragments with a molecular weight of 35, 38, and 42 kDa. These fragments released by MMP-19 significantly inhibited the proliferation of HMEC cells by 27% (p = 0.01) and reduced formation of capillary-like structures by 45% (p = 0.05) compared with control cells. As it is known that angiostatin blocks hepatocyte growth factor (HGF)-induced pro-angiogenic signaling in endothelial cells due to structural similarities to HGF, we have analyzed if the plasminogen fragments generated by MMP-19 interfere with this pathway. As it involves the activation of c-met, the receptor of HGF, we could show that MMP-19-dependent processing of plasminogen decreases the phosphorylation of c-met.</p> <p>Conclusion</p> <p>Altogether, MMP-19 exhibits an anti-angiogenic effect on endothelial cells via generation of angiostatin-like fragments.</p
Combined SEM-FIB-SPM-TOF-EDX-EBSD as a Multifunctional Tool
Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 - August 2, 201
Hot-dip-zinc-coating of prefabricated structural steel components
This JRC-Scientific and Technical Report gives information from pre-normative research for methods to prevent liquid metal assisted cracking of prefabricated structural components during zinc-coating in the liquid zinc melt, that may impair the structural safety of structures in which the components are built in.
This information provides a platform upon which further European design and product specifications can be developed. It may in particular affect the further developments of EN 1993, EN 1090, EN ISO 1461 and EN ISO 14713.
This report gives the state-of-the-art in understanding the mechanism of liquid metal assisted cracking in the zinc bath and methods and models that may be used to avoid it. It could be a basis to propose rules for the design of steel components intended to be hot-dip-zinc-coated in such a way that the design is consistent with execution rules for hot-dip-zinc-coating.
The workability of the rules proposed for all metal works and steel works that are fabricated under EN 1090 and galvanized according to the rules in this report is demonstrated by worked examples.JRC.DG.G.5-European laboratory for structural assessmen
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