Search results for "angle"

Spatial Search by Quantum Walk is Optimal for Almost all Graphs.

2015

The problem of finding a marked node in a graph can be solved by the spatial search algorithm based on continuous-time quantum walks (CTQW). However, this algorithm is known to run in optimal time only for a handful of graphs. In this work, we prove that for Erd\"os-Renyi random graphs, i.e.\ graphs of $n$ vertices where each edge exists with probability $p$, search by CTQW is \textit{almost surely} optimal as long as $p\geq \log^{3/2}(n)/n$. Consequently, we show that quantum spatial search is in fact optimal for \emph{almost all} graphs, meaning that the fraction of graphs of $n$ vertices for which this optimality holds tends to one in the asymptotic limit. We obtain this result by provin…

Investigation of heavy ion produced defect structures in insulators by small angle scattering

1985

Fast heavy ions produce stable defects in most dielectrica. As examples mica, Polyethylenterephtalat and Polystyrol were irradiated with Ar, Ni, Kr, Xe and U ions in an energy range from 0.5 up to 20 MeV/u. The resulting defects were investigated by neutron and x-ray small-angle scattering. The ion beam supplied by the UNILAC accelerator at GSI Darmstadt is characterized by its small emittance, the well defined mass, charge and energy of the ions and their stochastical distribution in the phase space. In scattering experiments the system of scattering centers created by these ions causes a scattered intensity distribution which strongly depends on the orientation of the sample with respect …

Analysis of small-angle scattering patterns from a commercial Al-Li alloy by means of a model incorporating a repulsive step potential

1992

Abstract Small-angle X-ray scattering measurements are reported for a commercial Al-8·49%Li-51% Cu (atomic composition) alloy solution treated at 520°C and thermally aged for several times at several temperatures. Data have been analysed by means of a model of ellipsoidal precipitate particles previously proposed by some of us and by a modification of this model where, in the interparticle interference term, allowance is made for interactions between the precipitate particles at longer range than previously. This was achieved by the introduction, in addition to the hard-sphere interaction potential, of a potential step. Our fits indicate that the precipitate particles interact through a rep…

A Rayleigh-Ritz approach for postbuckling analysis of variable angle tow composite stiffened panels

2018

Abstract A Rayleigh-Ritz solution approach for generally restrained multilayered variable angle tow stiffened plates in postbuckling regime is presented. The plate model is based on the first order shear deformation theory and accounts for geometrical nonlinearity through the von Karman’s assumptions. Stiffened plates are modelled as assembly of plate-like elements and penalty techniques are used to join the elements in the assembled structure and to apply the kinematical boundary conditions. General symmetric and unsymmetric stacking sequences are considered and Legendre orthogonal polynomials are employed to build the trial functions. A computer code was developed to implement the propose…

Kinetic evidence for the solubilization of pyridine-2-azo-p-dimethylaniline in alkanediyl-α,ω-bis(dimethylcetylammonium nitrate) surfactants. Role of…

2004

The incorporation of the bidentate ligand pyridine-2-azo-p-dimethylaniline (PADA) into micellar aggregates of the dimeric cationic surfactants propanediyl-, hexanediyl- and dodecanediyl-alpha,omega-bis(dimethylcetylammonium nitrate) (16-3-16,2NO(3)(-), 16-6-16,2NO(3)(-) and 16-12-16,2NO(3)(-), respectively) has been studied at 25 degreesC by examining the kinetics of the complexation reaction of the Ni(II) ion with this ligand. For comparison, cetyltrimethylammonium nitrate ( CTAN), which can be considered as the "monomeric'' surfactant of 16-3-16,2NO(3)(-), has also been used. The kinetic data have shown that, for 16-3-16,2NO(3)(-) and CTAN, at a surfactant concentration below the critical…

Magnetoelectrochemical modulation of pre-organization processes in a 4,4′-dinitrobiphenyl azacrown macrocyclic lactam

2004

A magnetoelectrochemical effect consisting on the modulation of the reaction rate of pre-organization reactions in a 4,4′-dinitrobiphenyl azacrown lactam is described. The electrochemical response of that compound in DMSO solution at microelectrodes consists in two successive dinitrobiphenyl-centred one-electron transfer processes at −0.9 and −1.6 V vs. AgCl/Ag involving the transition from the dihedral geometry of the neutral starting compound to the planar geometry of the final dianion, resulting in an overall ECE mechanism. In the presence of moderate (0.05–0.2 T) static magnetic fields, the second electron transfer process decreases significantly, the apparent rate constant of the dihed…

High-Generation Amphiphilic Janus-Dendrimers as Stabilizing Agents for Drug Suspensions

2018

Pharmaceutical nanosuspensions are formed when drug crystals are suspended in aqueous media in the presence of stabilizers. This technology offers a convenient way to enhance the dissolution of poorly water-soluble drug compounds. The stabilizers exert their action through electrostatic or steric interactions, however, the molecular requirements of stabilizing agents have not been studied extensively. Here, four structurally related amphiphilic Janus-dendrimers were synthesized and screened to determine the roles of different macromolecular domains on the stabilization of drug crystals. Physical interaction and nanomilling experiments have substantiated that Janus-dendrimers with fourth gen…

5,11,17,23-Tetranitro-25,26,27,28-tetrapentyloxycalix[4]arene

2005

The mol­ecule of the title compound, C48H60N4O12, is located on a crystallographic twofold rotation axis. It is found in the typical pinched cone conformation. The dihedral angles between the reference plane (defined by the C atoms of the methyl­ene bridges) and the benzene rings are 83.33 (6) and 141.61 (5)°.

Fast field cycling NMR relaxometry characterization of biochars obtained from an industrial thermochemical process

2012

Biochar has unique properties which make it a powerful tool to increase soil fertility and to contribute to the decrease of the amount of atmospheric carbon dioxide through the mechanisms of C sequestration in soils. Chemical and physical biochar characteristics depend upon the technique used for its production and the biomass nature. For this reason, biochar characterization is very important in order to address its use either for agricultural or environmental purposes. Three different biochars obtained from an industrial gasification process were selected in order to establish their chemical and physical peculiarities for a possible use in agronomical practices. They were obtained by char…

2014

Here we investigate the connection between topological order and the geometric entanglement, as measured by the logarithm of the overlap between a given state and its closest product state of blocks. We do this for a variety of topologically-ordered systems such as the toric code, double semion, color code, and quantum double models. As happens for the entanglement entropy, we find that for sufficiently large block sizes the geometric entanglement is, up to possible sub-leading corrections, the sum of two contributions: a bulk contribution obeying a boundary law times the number of blocks, and a contribution quantifying the underlying pattern of long-range entanglement of the topologically-…