A space X is sequentially separable if there is a countable D ? X such that every point of X is the limit of a sequence of points from D. Neither “sequential + separable” nor “sequentially separable” implies the other. Some examples of this are presented and some conditions under which one of the two implies the other are discussed. A selective version of sequential separability is also considered. 相似文献
We show how some problems coming from different fields of applied sciences, such as physics, engineering, biology, admit a common variational formulation characterized by the competition of two energetic terms. We discuss related problems and techniques studied by the authors and collaborators in the recent past as well open problems and further possible research directions in these topics. 相似文献
This paper is concerned with functionals with free discontinuities, considered as depending on the set variable. A splitting operation divides the sets in which the functional takes low values in the union of a noise part and a macroscopic part. Then we show lower semicontinuity results on the limit of the macroscopic parts by Hausdorff distance, along minimizing sequences. 相似文献
The sensitivity of an interferometric gravitational wave (GW) antenna operating above a few hundred Hertz is shot-noise limited. Sub-shot-noise sensitivity can be achieved by superimposing squeezed light on the laser field. The benefits of this approach are reduced in nonideal interferometers having fringe visibility less than unity, as pointed out by Gea-Banacloche and Leuchs and recently discussed by Chickarmane. Here, we consider an interferometer described by a set of coefficients Vl(k), Vsq(k), Vlsq(k) depending on the misalignment, mismatching, and aberrations of the optical systems, as well as on the asymmetry of the beam splitter and the two-arm losses. Due to the presence of terms proportional to the product of laser times squeezed fields, we have taken into account the amplitude fluctuations of al. A simple model of the squeezed vacuum light, produced by a degenerate optical parametric oscillator (OPO), is used for calculating the dependence of the spectral density of the output of a GW antenna on the fluctuations of the OPO-cavity resonance frequency, the pump amplitude fluctuation, and the nonlinear-crystal-temperature drift. A set of figures ηsq± and rlsq±(2) are introduced for describing the effects of the amplitude fluctuations and the relative line width γla on the spectral density of the quadrature phase operator X = alasq+ h.c. 相似文献
The redox aptitude of a series of cobalt(III) or cobalt(I) sandwich complexes bearing a charge compensated dicarbollide ligand
([9-L-7,8-C2B9H10]−) as a constant unit and different counterparts (varying from classical [7,8-C2B9H11]2− to charge-compensated [9-L-7,8-C2B9H10]− dicarbollides, from cyclopentadienyl [C5R5]− (R = Me, H) to cyclobutadiene [C4Me4]0 ligands) has been studied. All the Co(III) complexes display the reversible sequence Co(III)/Co(II)/Co(I). In contrast, the
Co(I) complexes (namely, those capped by tetramethylcyclobutadiene) accede reversibly only to the Co(II) oxidation state,
the passage to Co(III) being irreversible. When possible, the Co(II) intermediates have been characterized by EPR spectroscopy.
The molecular structures of the monocation [Co(η-9-SMe2-7,8-C2B9H10)2]+ in its DD/LL and meso diastereomeric forms as well as that of heteroleptic (η-7,8-C2B9H11)Co(η-9-SMe2-7,8-C2B9H10) have been obtained by single-crystal diffraction.
Presented at the 3rd Chianti Electrochemistry Meetings July 3−9, 2004, Certosa di Pontignano, Italy 相似文献
In order to investigate the effect of sol-gel coatings on the mechanical behavior of a high strength glass substrate, HF etched glass rods were used.
Coatings with different compositions (SiO2, ZrO2 and 20%ZrO2---80%SiO2) and different thicknesses were produced to study the influence of these parameters on strength.
Functions of integral probability versus strength were used to analyze data.
Coated glass rods exhibit higher strength in comparison with uncoated control rods that have undergone the same treatment. It seems evident that there is an effect of composition on strengthening. SiO2 coated rods displayed higher strength.
A lowering in strength at thickness higher than 0.2 μ was observed, independently of composition.
The effect of a saturated Ca(OH)2 solution was also studied. 相似文献
By means of newly designed optical instrumentation, mainly based on the use of integrating spheres, the fundamental optical properties of photovoltaic materials and devices (solar cells, modules) have been investigated. Relevant results concerned the optical loss (reflectance) of devices and the transmittance of semitransparent materials, used in the window sheets, under both direct and diffuse light. All the developed techniques are non-destructive and allow the characterization of selected areas of the samples. The use, however, of automatic translation stages makes easy to perform an optical and, in some cases, electrical mapping of the entire sample. 相似文献
An Fe/Ni multilayer of overall FeNi3 composition, prepared by Joule effect deposition, has been irradiated with 200 keV krypton ions at a nominal dose of 5×1015ions/cm2 to induce mixing at the interface. Depth profiling AES, RBS, XRD (glancing angle) and CEMS have been used to characterize the samples before and after irradiation and also after subsequent mild annealing. In the final structure, we have recognized the presence of embryos of an ordered FeNi3 superlattice. 相似文献