Fractional regression models for second stage DEA efficiency analyses

Data envelopment analysis (DEA) is commonly used to measure the relative efficiency of decision-making units. Often, in a second stage, a regression model is estimated to relate DEA efficiency scores to exogenous factors. In this paper, we argue that the traditional linear or tobit approaches to second-stage DEA analysis do not constitute a reasonable data-generating process for DEA scores. Under the assumption that DEA scores can be treated as descriptive measures of the relative performance of units in the sample, we show that using fractional regression models are the most natural way of modeling bounded, proportional response variables such as DEA scores. We also propose generalizations of these models and, given that DEA scores take frequently the value of unity, examine the use of two-part models in this framework. Several tests suitable for assessing the specification of each alternative model are also discussed.Second-stage DEA; Fractional data; Specification tests; One outcomes; Two-part models.

Valence quark and meson cloud contributions for the gamma* Lambda -> Lambda* and gamma* Sigma0 -> Lambda* reactions

We estimate the valence quark contributions for the gamma* Y -> Lambda* (Y=Lambda, Sigma0) electromagnetic transition form factors. We focus particularly on the case Lambda*=Lambda(1670) as an analog reaction with gamma* N -> N(1535). The results are compared with those obtained from chiral unitary model, where the Lambda* resonance is dynamically generated and thus the electromagnetic structure comes directly from the meson cloud excitation of the baryon ground states. The form factors for the case Y=Sigma0 in particular, depend crucially on the two real phase (sign) combination, a phase between the Lambda and Lambda* states, and the other, the phase between the Lambda and Sigma0 radial wave functions. Depending on the combination of these two phases, the form factors for the gamma* Sigma0 -> Lambda* reaction can be enhanced or suppressed. Therefore, there is a possibility to determine the phase combination by experiments.Comment: 17 pages, 7 figure

Octet baryon electromagnetic form factors in nuclear medium

We study the octet baryon electromagnetic form factors in nuclear matter using the covariant spectator quark model extended to the nuclear matter regime. The parameters of the model in vacuum are fixed by the study of the octet baryon electromagnetic form factors. In nuclear matter the changes in hadron properties are calculated by including the relevant hadron masses and the modification of the pion-baryon coupling constants calculated in the quark-meson coupling model. In nuclear matter the magnetic form factors of the octet baryons are enhanced in the low $Q^2$ region, while the electric form factors show a more rapid variation with $Q^2$. The results are compared with the modification of the bound proton electromagnetic form factors observed at Jefferson Lab. In addition, the corresponding changes for the bound neutron are predicted.Comment: Version accepted for publication in J.Phys. G. Few changes. 40 pages, 14 figures and 8 table

Studies of decolorization of azo dyes by ascomycete yeasts

Poster apresentado no Micro'2001, Póvoa de Varzim, 2001.Azo dyes are the most widely used colored materials in textile industries and its biodegradability is, therefore, an important issue in the biological treatment of dye-containing wastewater. However, these treatments are not totally effective in removing color of textile dye wastewater since dyes are typically resistant to oxidative degradation. Most biodegradation studies on azo dyes involve bacterial species, and anaerobic or microaerophylic conditions are usually refered to as being favorable to a reduction step producing colorless amines. Our group has succeeded in isolating a number of yeast species, which revealed an interesting potential in the color removal of azo dyes in aerated culture media. Three of these species (UM2, UM41 and UM45), where used in the present work. The tested dyes included several sulphonic and carboxylic monoazo dyes, and several reactive textile dyes. The results which will be described refer to (i) the conditions and time-course of the decolorization process, (ii) the optimization of the decolorization medium, aiming at the reduction in yeast extract concentration, (iii) the identification of dye reduction products formed in the course of the decolorization process and (iv) the effect of those reduction products on yeast specific growth rates.BIOEFTEX Project

Telecommuting potential analysis

Commuting is a problem for developed societies that translates into economic, social and environmental losses. This study is set to explore the potential of telecommuting. The empirical study started with interviews to build a survey that was answered by 126 Lisbon commuters. Results show interviewees perceived telecommuting consequences are in line with extant research and that attitudes towards telecommuting (productivity, and cost savings) are predictors of the intention to accept telecommuting offers. Likewise, professional tenure and work-to-home stress foster a more favourable attitude related to productivity / quality of working life while displacement mode (active) and home-to-work stress foster a more favourable attitude related with cost savings. The study concludes that there is considerable potential for telecommuting and that the process of implementing telecommuting as an HRM policy is doable based on the attitudes identified in the model developed.info:eu-repo/semantics/acceptedVersio

Identifying the Azobenzene/Aniline reaction intermediate on TiO2-(110) : a DFT Study

Density functional theory (DFT) calculations, both with and without dispersion corrections, have been performed to investigate the nature of the common surface reaction intermediate that has been shown to exist on TiO2(110) as a result of exposure to either azobenzene (C6H5N═NC6H5) or aniline (C6H5NH2). Our results confirm the results of a previous DFT study that dissociation of azobenzene into two adsorbed phenyl imide (C6H5N) fragments, as was originally proposed, is not energetically favorable. We also find that deprotonation of aniline to produce this surface species is even more strongly energetically disfavored. A range of alternative surface species has been considered, and while dissociation of azobenzene to form surface C6H4NH species is energetically favored, the same surface species cannot form from adsorbed aniline. On the contrary, adsorbed aniline is much the most stable surface species. Comparisons with experimental determinations of the local adsorption site, the Ti–N bond length, the molecular orientation, and the associated C 1s and N 1s photoelectron core level shifts are all consistent with the DFT results for adsorbed aniline and are inconsistent with other adsorbed species considered. Possible mechanisms for the hydrogenation of azobenzene required to produce this surface species are discussed

Taxonomia de Beania (Bryozoa, Flustrina) de Arraial do Cabo, Estado do Rio de Janeiro, Brasil

Five species of Beania Johnston, 1840 (Bryozoa: Flustrina) were previously reported from Brazil, but only one, identified incorrectly in the literature as B. intermedia (Hincks, 1881), was reported from Rio de Janeiro State. In this study, we describe three species of Beania from Arraial do Cabo, Rio de Janeiro State: Beania klugei Cook, 1968 (=B. intermedia sensu Marcus, 1937), Beania mirabilis Johnston, 1840, and Beania maxilladentata sp.nov. Beania mirabilis is a new record for Rio de Janeiro State. It is characterized by a long basal cauda, approximately as long as the rest of the autozooid, two pairs of oral spines, and usually five pairs of short marginal spines overarching the frontal membrane. Beania klugei is characterized by the absence of both oral and marginal spines, and by its large autozooids and small avicularia. Beania maxilladentata sp.nov. has autozooids with up to three pairs of marginal spines directed outwards; the distal end of the autozooid never overlaps the proximal end of the next zooid in series; and the avicularia are as long as wide, with mandibles with accessory tips. Our study raises the number of species of Beania known in Rio de Janeiro State from one to three, and along the Brazilian coast from five to six.Cinco espécies de Beania Johnston, 1840 (Bryozoa: Flustrina) são conhecidas do Brasil, mas somente uma, identificada incorretamente na literatura como B. intermedia (Hincks 1881), é conhecida do Estado do Rio de Janeiro. Neste estudo, descrevemos três espécies de Beania de Arraial do Cabo, Estado do Rio de Janeiro: Beania klugei Cook, 1968 (=B. intermedia sensu Marcus, 1937), Beania mirabilis Johnston, 1840 e Beania maxilladentata sp.nov. Beania mirabilis Johnston, 1840 é um novo registro para a costa do Rio de Janeiro; é caracterizada por apresentar uma longa cauda basal, aproximadamente tão longa quanto o resto do autozoóide, um par de espinhos orais e usualmente cinco pares de curtos espinhos marginais arqueados sobre a membrana frontal. Beania klugei é caracterizada pela ausência de espinhos orais e marginais, por seus autozoóides grandes e pequenas aviculárias. Beania maxilladentata sp.nov. é caracterizada por autozoóides com até três pares de espinhos marginais dirigidos para o exterior; a extremidade distal do autozoóide nunca recobre o autozoóide subseqüente; a aviculária é tão longa quanto larga e a mandíbula tem pontas acessórias. O número de espécies de Beania conhecidas aumentou de uma para três no Estado do Rio de Janeiro e de cinco para seis na costa brasileira

Hand-based multimodal identification system with secure biometric template storage

WOS:000304107200001This study proposes a biometric system for personal identification based on three biometric characteristics from the hand, namely: the palmprint, finger surfaces and hand geometry. A protection scheme is applied to the biometric template data to guarantee its revocability, security and diversity among different biometric systems. An error-correcting code (ECC), a cryptographic hash function (CHF) and a binarisation module are the core of the template protection scheme. Since the ECC and CHF operate on binary data, an additional feature binarisation step is required. This study proposes: (i) a novel identification architecture that uses hand geometry as a soft biometric to accelerate the identification process and ensure the system's scalability; and (ii) a new feature binarisation technique that guarantees that the Hamming distance between transformed binary features is proportional to the difference between their real values. The proposed system achieves promising recognition and speed performances on two publicly available hand image databases.info:eu-repo/semantics/acceptedVersio