Optimized Multimode Interference Fiber Based Refractometer in A Reflective Interrogation Scheme

A fiber based refractometer in a reflective interrogation scheme is investigated and optimized. A thin gold film was deposited on the tip of a coreless fiber section, which is spliced with a single mode fiber. The coreless fiber is a multimode waveguide, and the observed effects are due to multimode interference. To investigate and optimize the structure, the multimode part of the sensor is built with 3 different lengths: 58 mm, 29 mm and 17 mm. We use a broadband light source ranging from 1475 nm to 1650 nm and we test the sensors with liquids of varying refractive indices, from 1.333 to 1.438. Our results show that for a fixed wavelength, the sensor sensitivity is independent of the multimode fiber length, but we observed a sensitivity increase of approximately 0.7 nm/RIU for a one-nanometer increase in wavelength

Enhancing the Sensitivity of SMS Fiber Sensors by the Use of High Refractive Index Coatings

This paper presents a study on the behavior of single-mode/multimode/single-mode sensors with diamond-like carbon coating of high refractive index. Spectra and response for different values of the external medium refractive index are recorded and analyzed

Artistic work and structural organization of theater groups in Lisbon area. Five empirical standpoints to inform public policies.

Organizational structures in the cultural and creative sectors are being challenged by deep changes in the economic, cultural and governance frameworks in which they operate. These changes force them to assume increasingly differentiated strategies to face the challenges that thus emerge. This phenomenon increases the complexity of the analysis of the art worlds and it also brings new challenges to the conception of public policies for these sectors. This is particularly visible in the field of the performing arts; when we observe the evolution of organizational structures, the professional paths and individual careers, as well as when we witness the indecisions and dilemmas in contemporary public policies in those fields. Drawing from a theoretical discussion based on recent contributions of sociology and economics of the arts and culture, and departing from a typology previously suggested elsewhere by the authors, this paper offers an empirical standpoint towards five dimensions of theater groups’ work in order to extract conclusions that may inform public policy decisions: organizational structure, artistic work, art world commitment, economic structure and geographical scope.FC

Evolution of density perturbations in decaying vacuum cosmology: The case of non-zero perturbations in the cosmological term

We extend the results of a previous paper where a model of interacting dark energy, with a cosmological term decaying linearly with the Hubble parameter, is tested against the observed mass power spectrum. In spite of the agreement with observations of type Ia supernovas, baryonic acoustic oscillations and the cosmic microwave background, we had shown previously that no good concordance is achieved if we include the mass power spectrum. However, our analysis was based on the ad hoc assumption that the interacting cosmological term is strictly homogeneous. Now we perform a more complete analysis, by perturbing such a term. Although our conclusions are still based on a particular, scale invariant choice of the primordial spectrum of dark energy perturbations, we show that a cosmological term decaying linearly with the Hubble parameter is indeed disfavored as compared to the standard model.Comment: Version accepted for publication in Physical Review

Irreducible actions and compressible modules

Any finite set of linear operators on an algebra $A$ yields an operator algebra $B$ and a module structure on A, whose endomorphism ring is isomorphic to a subring $A^B$ of certain invariant elements of $A$. We show that if $A$ is a critically compressible left $B$-module, then the dimension of its self-injective hull $A$ over the ring of fractions of $A^B$ is bounded by the uniform dimension of $A$ and the number of linear operators generating $B$. This extends a known result on irreducible Hopf actions and applies in particular to weak Hopf action. Furthermore we prove necessary and sufficient conditions for an algebra A to be critically compressible in the case of group actions, group gradings and Lie actions

A typing error in Tokeshi's test of bimodality

Copyright © 2003 Blackwell Publishing“One way to describe patterns of species distribution is to plot the frequency histograms using species–range-size data (Gaston, 1994; Brown, 1995; Gaston & Blackburn, 2000). Usually the untransformed geographical ranges of species are distributed following a ‘hollow curve’, i.e. most species have narrow ranges and very few have widespread distributions. This highly ‘right-skewed’ curve has been regarded as unimodal (e.g. Gaston, 1994). In some cases, however, the species-range-size distribution shows a bimodal pattern (Hanski, 1982; Brown, 1984, 1995; Gaston, 1994; Gaston & Blackburn, 2000), in which to the left-hand mode is added a right hand mode generated by the widespread group of species that occur in almost all sampled sites. The ‘core-satellite species hypothesis’ (Hanski, 1982) and the ‘resource usage model’ (Brown, 1984, 1995) were proposed to explain the finding that a few species are regionally common (widespread) and locally abundant (the ‘core’ species in Hanski’s model; the generalists or broad-niched species in Brown’s model), while most species can be regarded as having smaller ranges and low local abundances (the ‘satellite’ species in Hanski’s model; the specialists or narrow-niched species in Brown’s model). […]