Search results for "Weak"
showing 10 items of 1417 documents
Shedding Light on the Interactions of Hydrocarbon Ester Substituents upon Formation of Dimeric Titanium(IV) Triscatecholates in DMSO Solution
2020
Abstract The dissociation of hierarchically formed dimeric triple lithium bridged triscatecholate titanium(IV) helicates with hydrocarbyl esters as side groups is systematically investigated in DMSO. Primary alkyl, alkenyl, alkynyl as well as benzyl esters are studied in order to minimize steric effects close to the helicate core. The 1H NMR dimerization constants for the monomer–dimer equilibrium show some solvent dependent influence of the side chains on the dimer stability. In the dimer, the ability of the hydrocarbyl ester groups to aggregate minimizes their contacts with the solvent molecules. Due to this, most solvophobic alkyl groups show the highest dimerization tendency followed by…
Stochastic Differential Equations
2020
Stochastic differential equations describe the time evolution of certain continuous n-dimensional Markov processes. In contrast with classical differential equations, in addition to the derivative of the function, there is a term that describes the random fluctuations that are coded as an Ito integral with respect to a Brownian motion. Depending on how seriously we take the concrete Brownian motion as the driving force of the noise, we speak of strong and weak solutions. In the first section, we develop the theory of strong solutions under Lipschitz conditions for the coefficients. In the second section, we develop the so-called (local) martingale problem as a method of establishing weak so…
Alle Wege Führen Zum Text
2016
The intention of this chapter is to review the development of linguistic research during the twentieth century in Europe and the United States, in order to show that the genesis of text linguistics as a comprehensive theoretical framework was necessary, considering the events from a post-eventum perspective. Firstly, structural linguistics is presented as well as its main exponents; secondly, generative linguistics is discussed; thirdly, the genesis and the development of text linguistics is presented. Concerning the structural linguistics, the key issues investigated by 4 linguists (namely, de Saussure, Benveniste, Hjelmslev and Bloomfield) are summarized. Concerning the generative linguis…
Pattern formation driven by cross-diffusion
2009
In this work we are interested in describing the mechanism of pattern formation for a reaction-diffusion system with nonlinear diffusion terms (which take into account the self and the cross-diffusion effects). The reaction terms are chosen of the Lotka-Volterra type in the competitive interaction case. The cross-diffusion is proved to be the key mechanism of pattern formation via a linear stability analysis. A weakly nonlinear multiple scales analysis is carried out to predict the amplitude and the form of the pattern close to the bifurcation threshold. In particular, the Stuart-Landau equation which rules the evolution of the amplitude of the most unstable mode is found. In the subcritica…
Size dependence of the Josephson critical behavior in pyrolytic graphite TEM lamellae
2014
We have studied the transport characteristics of TEM lamellae of different widths obtained from a graphite sample with electrical contacts at the edges of the embedded interfaces. The temperature dependence of the resistance, as well as the current-voltage characteristics, are compatible with the existence of Josephson-coupled superconducting regions. The transition temperature at which the Josephson behavior sets in decreases with a decreasing interface width and vanishes for widths below 200 nm. This interface-size dependence provides an explanation for differences observed in the transport behavior of graphite-based samples with interfaces, and it appears to be related to the influence o…
Effects of Weak Links in the Nonlinear Microwave Response of MgB2 Superconductor
2006
We report experimental results of second-harmonic (SH) response at microwave frequency in several ceramic MgB2 samples, prepared by different methods. The SH signal has been investigated as a function of the temperature and DC magnetic field. The investigation has been carried out at low magnetic fields, where nonlinear processes arising from motion of Abrikosov fluxons are ineffective. We show that the low-temperature SH emission is ascribable to processes involving weak links. Comparison among the peculiarities of the SH signal radiated by the different samples shows that the presence of weak links strongly depends on the sample preparation method, as well as the purity and morphology of …
Quantum Nanoplasmonic : from dressed atom picture to superradiance
2019
Controlling quantum emitters (atoms, molecules, quantum dots, etc.), light, and its interactions is a key issue for implementing devices for information optical processing at the quantum level. For example, controlling dynamics of emitters coupled to a high-Q cavity can be achieved through cavity quantum electrodynamics (cQED). Plasmonic structures hybrid system are of growing interest in the quantum control at the nanoscale because of their capability to confine light beyond the diffraction limit. However, its application appears notoriously limited in practical situations due to the intrinsic presence of numerous and lossy modes, which complicates the description and the interpretation of…
Stefan-Boltzmann Radiation on Non-convex Surfaces
1997
We consider the stationary heat equation for a non-convex body with Stefan–Boltzmann radiation condition on the surface. The main virtue of the resulting problem is non-locality of the boundary condition. Moreover, the problem is non-linear and in the general case also non-coercive and non-monotone. We show that the boundary value problem has a maximum principle. Hence, we can prove the existence of a weak solution assuming the existence of upper and lower solutions. In the two dimensional case or when a part of the radiation can escape the system we obtain coercivity and stronger existence result. © 1997 by B.G. Teubner Stuttgart-John Wiley & Sons, Ltd.
A measurement of the antineutrino asymmetry B in free neutron decay
2005
Abstract We have measured the antineutrino asymmetry B in neutron beta decay, i.e., the correlation of the neutron spin and the antineutrino momentum, with a new method. Our result is B = 0.967 ± 0.006 stat ± 0.010 syst = 0.967 ± 0.012 . Statistical and systematic uncertainty can be considerably reduced in future experiments.
Discovering the Senses of an Ambiguous Word by Clustering its Local Contexts
2005
As has been shown recently, it is possible to automatically discover the senses of an ambiguous word by statistically analyzing its contextual behavior in a large text corpus. However, this kind of research is still at an early stage. The results need to be improved and there is considerable disagreement on methodological issues. For example, although most researchers use clustering approaches for word sense induction, it is not clear what statistical features the clustering should be based on. Whereas so far most researchers cluster global co-occurrence vectors that reflect the overall behavior of a word in a corpus, in this paper we argue that it is more appropriate to use local context v…