Search results for "rigid"
showing 10 items of 188 documents
Failure of topological rigidity results for the measure contraction property
2014
We give two examples of metric measure spaces satisfying the measure contraction property MCP(K,N) but having different topological dimensions at different regions of the space. The first one satisfies MCP(0,3) and contains a subset isometric to $\mathbb{R}$, but does not topologically split. The second space satisfies MCP(2,3) and has diameter $\pi$, which is the maximal possible diameter for a space satisfying MCP(N-1,N), but is not a topological spherical suspension. The latter example gives an answer to a question by Ohta.
The method of moving planes: a quantitative approach
2018
We review classical results where the method of the moving planes has been used to prove symmetry properties for overdetermined PDE's boundary value problems (such as Serrin's overdetermined problem) and for rigidity problems in geometric analysis (like Alexandrov soap bubble Theorem), and we give an overview of some recent results related to quantitative studies of the method of moving planes, where quantitative approximate symmetry results are obtained.
Conformational behaviour of 2,2?-bipyrrole
1986
The rotational potential around the interannular bond in 2,2′-bipyrrole has been calculated making use of standard minimal STO-3G and split valence 4-31G basis sets. Geometrical optimization concerning the most significant interannular internal parameters has been performed with both basis sets. The trans conformer is predicted to be more stable than the cis. The minimal basis set predicts the existence of a cisoid-gauche minimum which after limited optimization becomes very shallow and it seems to be an artifact of the rigid rotor approximation. At 4-31G level, both the trans and cis conformers represent maxima in the potential curve and two gauche minima appear at θ=46.0° and θ=147.6°, th…
Familial mixed congenital myopathy with rigid spine phenotype
1997
We describe a father and daughter with a rigid spine syndrome and proximal myopathy. The index patient was a 42-year-old man, who died from respiratory failure after a lifelong, slowly progressive proximal myopathy and a rigid spine phenotype. This was morphologically characterized by cytoplasmic bodies, increased desmin, features of reducing-body myopathy, and sarcoplasmic and intranuclear tubulofilamentous inclusions. These cases are characterized by an early onset and possibly autosomal-dominant inheritance, with associated complex structural hallmarks of both desmin-related and inclusion body myopathies. Together they may be defined as a complex mixed congenital myopathy with a rigid sp…
Effect of cholesterol on the physical properties of pulmonary surfactant films: Atomic force measurements study
2006
International audience; Atomic force measurements were performed on supported pulmonary surfactant (PS) films to address the effect of cholesterol on the physical properties of lung surfactant films. We recently found that cholesterol in excess of a physiological proportion abolishes surfactant function, and is the reason that surfactant fails to lower the surface tension upon compression. In this study, we investigated how the loss of mechanical stability observed earlier is related to the local mechanical properties of the film by local force measurements. The presence of 20% of cholesterol in bovine lipid extract surfactant (BLES) resulted in a decrease of the observed adhesive interacti…
A novel bio-orthogonal cross-linker for improved protein/protein interaction analysis
2015
International audience; The variety of protein cross-linkers developed in recent years illustrates the current requirement for efficient reagents optimized for mass spectrometry (MS) analysis. To date, the most widely used strategy relies on commercial cross-linkers that bear an isotopically labeled tag and N-hydroxysuccinimid-ester (NHS-ester) moieties. Moreover, an enrichment step using liquid chromatography is usually performed after enzymatic digestion of the cross-linked proteins. Unfortunately, this approach suffers from several limitations. First, it requires large amounts of proteins. Second, NHS-ester cross-linkers are poorly efficient because of their fast hydrolysis in water. Fin…
Toward engineering efficient peptidomimetics. Screening conformational landscape of two modified dehydroaminoacids
2013
Effective peptidomimetics should posses structural rigidity and appropriate interaction pattern leading to potential spatial and electronic matching to the target receptor site. Rational design of such small bioactive molecules could push chemical synthesis and molecular modeling toward faster progress in medicinal chemistry. Conformational properties of N-t-butoxycarbonyl-glycine-(E/Z)-dehydrophenylalanine N′,N′-dimethylamides (Boc-Gly-(E/Z)-ΔPhe-NMe2) in chloroform were studied by NMR and IR spectroscopy. The experimental findings were supported by extensive calculations at DFT(B3LYP, M06-2X) and MP2 levels of theory and the β-turn tendency for both isomers of the studied dipeptide were d…
Attendibilità dei modelli per la valutazione dei moduli elastici delle murature suggeriti dalle norme tecniche
2012
In this paper the results of an experimental investigation aimed to the assessment of Young moduli, rigidity moduli and other mechanical properties for different types of masonry are shown. The mechanical characteristics predicted by models proposed by some technical codes were compared against experimental data. This study was motivated by the suggestion of the Masonry Standards Joint Committee's (MSJC) code that, while proposing the use of such models, acknowledges the lack of testing in support of their validation. The experimental investigation has included compressive tests on components (blocks and mortar), diagonal compressive tests and ordinary compressive tests (orthogonally to bed…
Rigidity of quasi-isometries for symmetric spaces and Euclidean buildings
1997
Abstract We study quasi-isometries between products of symmetric spaces and Euclidean buildings. The main results are that quasi-isometries preserve the product structure, and that in the irreducible higher rank case, quasi-isometries are at finite distance from homotheties.
Gas-filled recoil separator for studies of heavy elements
1995
Abstract A gas-filled recoil separator for the study of heavy elements has been constructed. The separator is of type QDQQ with the first, vertically focusing, quadrupole providing improved matching to the acceptance of the dipole magnet. The separator has been designed also for use in vacuum mode in which case a mass resolving power of ≈ 100 is estimated. The deflection angle is 25° and the radius of curvature is 1850 mm. Maximum beam rigidity is 2.2 T m. In the first experiments, new isotopes in the region Z = 85–90 have been synthesized.