The Phase Diagram of the U(2)×U(2)U(2)\times U(2) Sigma Model

We study the phase diagram of the $U(2) \times U(2)$ scalar model in $d=4$ dimensions. We find that the phase transition is of first order in most of the parameter space. The theory can still be relevant to continuum physics (as an effective theory) provided the transition is sufficiently weakly first order. This places restrictions on the allowed coupling constants.Comment: 3 pages (Latex), 2 eps figures, uses espcrc2.sty, epsf, talk given at LATTICE9

Master Formula Approach to Chiral Symmetry Breaking: Pi-Pi scattering

The master formula approach to chiral symmetry breaking is used to analyze the phase shifts for $\pi\pi$ scattering in the elastic region. The results are in excellent agreement with the data for the phase shifts up to the K-K bar threshold. Our analysis shows that the pi-pi data near threshold in the scalar channel favors a large quark condensate in the vacuum, i.e. \sim -(240 MeV)^3.Comment: 17 pages, LaTeX, 1 postscript file of 12 figures in addition. Equation 2 is changed, the rest is the sam

Dilepton and Photon Emission Rates from a Hadronic Gas III

We extend our early analyses of the dilepton and photon emission rates from a hadronic gas to account for strange mesons using a density expansion. The emission rates are reduced to vacuum correlation functions using three-flavor chiral reduction formulas, and the latters are assessed in terms of empirical data. Using a fire-ball, we compare our results to the low and intermediate mass dilepton data available from CERN. Our results suggest that a baryon free hadronic gas does not account for the excess of low mass dielectrons observed at CERES but do well in accounting for the intermediate dimuons at HELIOS. The same observations apply to the recent low and high $p_t$ dielectron rates from CERES.Comment: 12 pages LaTeX, 11 eps figure

Dilepton and Photon Emission Rates from a Hadronic Gas

We analyze the dilepton and photon emission rates from a hadronic gas using chiral reduction formulas and a virial expansion. The emission rates are reduced to pertinent vacuum correlation functions, most of which can be assessed from experiment. Our results indicate that in the low mass region, the dilepton and photon rates are enhanced compared to most of the calculations using chiral Lagrangians. The enhancement is further increased through a finite pion chemical potential. An estimate of the emission rates is also made using Haag's expansion for the electromagnetic current. The relevance of these results to dilepton and photon emission rates in heavy-ion collisions is discussed.Comment: 7 pages, LaTeX using revTeX, 6 figures imbedded in text. Figures slightly changed, text left unchange

Revisiting the security of speaker verification systems against imposture using synthetic speech

In this paper, we investigate imposture using synthetic speech. Although this problem was first examined over a decade ago, dramatic improvements in both speaker verification (SV) and speech synthesis have renewed interest in this problem. We use a HMM-based speech synthesizer which creates synthetic speech for a targeted speaker through adaptation of a background model. We use two SV systems: standard GMMUBM- based and a newer SVM-based. Our results show when the systems are tested with human speech, there are zero false acceptances and zero false rejections. However, when the systems are tested with synthesized speech, all claims for the targeted speaker are accepted while all other claims are rejected. We propose a two-step process for detection of synthesized speech in order to prevent this imposture. Overall, while SV systems have impressive accuracy, even with the proposed detector, high-quality synthetic speech will lead to an unacceptably high false acceptance rate

Modelagem difusa para suporte à decisão na descoberta de SNPs em sequências de cDNA.

Diferenças pontuais entre pares de bases de diferentes sequências alinhadas são o tipo mais comum de variabilidade genética. Tais diferenças, conhecidas como polimorfismos de base única (single nucleotide polymorphisms - SNPs), são importantes no estudo davariabilidade das espécies, pois podem provocar alterações funcionais ou fenotípicas, as quais podem implicar em consequências evolutivas ou bioquímicas nos indivíduos das espécies. A descoberta de SNPs por algoritmos computacionais é uma prática bastante difundida e o presente texto apresenta um modelo que se baseia em lógica difusa (fuzzy logic) para, a partir de resultados prévios, auxiliar na tomada de decisão, nos casos em que as informações preliminares sejam divergentes, assim como, na confirmação de informações coincidentes.SBIAgro 2009

Modelagem difusa para suporte à decisão na descoberta de SNPs em sequências de cDNA.

Diferenças pontuais entre pares de bases de diferentes sequências alinhadas são o tipo mais comum de variabilidade genética. Tais diferenças, conhecidas como polimorfismos de base única (single nucleotide polymorphisms – SNPs), são importantes no estudo davariabilidade das espécies, pois podem provocar alterações funcionais ou fenotípicas, as quais podem implicar em consequências evolutivas ou bioquímicas nos indivíduos das espécies. A descoberta de SNPs por algoritmos computacionais é uma prática bastante difundida e o presente texto apresenta um modelo que se baseia em lógica difusa (fuzzy logic) para, a partir de resultados prévios, auxiliar na tomada de decisão, nos casos em que as informações preliminares sejam divergentes, assim como, na confirmação de informações coincidentes