Oral lichen planus versus epithelial dysplasia: difficulties in diagnosis

O diagnóstico histopatológico do líquen plano bucal não é fácil, pois alguns casos de displasia epitelial podem apresentar características bastante semelhantes às do líquen plano. OBJETIVO: Comparar as alterações celulares sugestivas de malignidade presentes no líquen plano bucal com as da displasia epitelial. MATERIAL E MÉTODOS: Cortes histológicos de líquen plano bucal e displasia, corados com hematoxilina-eosina, foram analisados por meio da microscopia de luz. RESULTADOS: A análise de variância (alfa=5%) revelou haver diferença estatisticamente significante entre o número médio de alterações celulares no líquen plano bucal (5,83±1,61) e na displasia epitelial (4,46±1,26). O teste de qui-quadrado não mostrou diferença estatisticamente significante entre o líquen plano bucal e a displasia epitelial em relação às seguintes alterações celulares: aumento da relação núcleo/citoplasma, hipercromatismo nuclear, distribuição irregular da cromatina e núcleos aumentados (p>0,05). CONCLUSÃO: Algumas alterações celulares sugestivas de malignidade presentes no líquen plano bucal também podem ser encontradas na displasia epitelial, dificultando o seu diagnóstico e, consequentemente enfatizando a importância do acompanhamento a longo prazo dos pacientes com a doença.

Análise histoquímica foliar do amendoim: genótipos 'Tatu' e SO-909

Este trabalho teve por finalidade a análise histoquímica foliar de dois genótipos de amendoim (Arachis hypogaea L.), do tipo botânico Valência: SO-53 ('Tatu') e SO-909 (PI-259747), cuja literatura demonstra apresentarem respostas diferentes de resistência às principais moléstias fúngicas foliares do Brasil. Seções transversais das seguintes estruturas - pulvino, haste peciolar, raque, pulvínulo e folíolo - e seções paradérmicas de folíolos coletados em dois anos agrícolas consecutivos, foram analisadas quanto à presença de alcalóides, amido, calose, celulose pura, celulose com pectina, cera, cristais, cutina, lignina, mucilagem, óleo, resina, tanino e ureídeos (micrograma) por folíolo (grama). As diferenças qualitativas histoquímicas observadas nos diversos tecidos, como a freqüência de tanino, alcalóide, pectina e óleo, supostamente, podem ser responsáveis pela resistência ou suscetibilidade dos genótipos às moléstias fúngicas foliares. Para fins de caracterização, mostrou-se eficiente a avaliação de pureza de celulose.

ASPECTOS MORFOANATÔMICOS DE FRUTOS DE TOMATEIRO CULTIVAR ÂNGELA GIGANTE, SUBMETIDOS A TRATAMENTOS COM REGULADORES VEGETAIS

O presente trabalho teve como finalidade obter dados morfológicos de frutos de tomateiro, Lycopersicon esculentum Mill. `Ângela Gigante', submetidos à ação de reguladores vegetais, em dois ensaios que ocorreram em épocas distintas, em casa de vegetação. As mudas foram selecionadas e transplantadas para vasos com capacidade de 12 L de terra, contendo uma mistura de solo argiloso, areia, matéria orgânica e uma adubação mineral complementar de N, P, K. No segundo ensaio, após o transplante das mudas, além da adubação mineral complementar de N, P, K, efetuaram-se adubações adicionais (fertirrigação). em ambos os ensaios, quando as plantas atingiram quatro folhas definitivas, realizaram-se as pulverizações com giberelina, GA3 50 mg/L; ácido naftalenacético, NAA 100 mg/L; cloreto (2-cloroetil) trimetilamônio, CCC 1.500 mg/L e ácido succínico -2,2 dimetil-hidrazida, SADH 3.000 mg/L. em relação aos estudos anatômicos, observou-se que os tratamentos com retardadores vegetais (CCC e SADH) produziram frutos firmes, com formato tipo barril e ombros salientes; entretanto, em seção transversal, notou-se perda de viscosidade e atrofia de sementes, principalmente nos frutos de plantas tratadas com SADH. Os tratamentos com NAA e GA3 causaram eventual formação de frutos geminados. O tratamento com GA3 apresentou o parênquima do pericarpo com grãos de amido em processo de fragmentação, provavelmente em virtude de o GA3 acelerar a atividade da amilase, afetando o processo de maturação dos frutos e transformando o amido em açúcares. Notaram-se no mesocarpo células com grande quantidade de cristais de oxalato de cálcio sob a forma de areia cristalina. do tratamento com CCC resultaram frutos suculentos com células da placenta degeneradas, deixando livre grande quantidade de mucilagem. O pericarpo apresentou grande quantidade de grãos de amido composto em toda a extensão, provavelmente por haver um atraso no processo de maturação dos frutos.

SEMICLASSICAL ESTIMATE OF THE COULOMB-EXCITATION OF THE GIANT-DIPOLE RESONANCE IN PB-208

A semiclassical approach to study pure Coulomb excitation of Pb-208 giant dipole isovector resonance is examined. We consider medium energy projectiles and assume the target excitation to be described by a simple Goldhaber-Teller model. It is shown that the main features concerning the angular distribution are obtained in the angular range described by the model and an estimate is made of the pure Coulomb dipole contribution to the measured cross sections.

Positron-helium scattering at medium energies

We present results for medium-energy elastic, inelastic [transition to He(1s2(1)s), He(1s2(1)p), He(1s3(1)s), and He(1s3(1)p) states], capture [to Ps(1s), Ps(2s), and Ps(2p) states of the positronium (Ps) atom] and total cross sections of positron-helium scattering in the close coupling approach using realistic wave functions.

TRIPLE-VECTOR-BOSON PROCESSES IN GAMMA-GAMMA COLLIDERS

We study the production of three gauge bosons (W(+)W(-)Z(0) and W(+)W(-)gamma) at the next generation of linear e(+)e(-) colliders operating in the yy mode. We analyze the total cross sections as well as several kinematical distributions of the final state particles. We find out that a linear e(+)e(-) machine operating in the rr mode will produce 5-10 times more three-gauge-boson states compared to the standard e(+)e(-) mode at high energies.

Resonance in positron-helium scattering at medium energy

A narrow S-wave resonance has been found in the positron-helium system at about 30 eV, using the close-coupling approach, in excitation and rearrangement cross sections to He(1s2s), He(1s2p), Ps(1s) and Ps(2s) states by employing different combinations of the following basis functions: He(1s1s), He(1s2s), He(1s2p), Ps(1s) and Ps(2s), where Ps stands for the positronium atom.

Effect of the bound nucleon form factors on charged-current neutrino-nucleus scattering

We study the effect of bound nucleon form factors on charged-current neutrino-nucleus scattering. The bound nucleon form factors of the vector and axial-vector currents are calculated in the quark-meson coupling model. We compute the inclusive C-12(nu(mu),mu(-))X cross sections using a relativistic Fermi gas model with the calculated bound nucleon form factors. The effect of the bound nucleon form factors for this reaction is a reduction of similar to8% for the total cross section, relative to that calculated with the free nucleon form factors.

POSITRON-HELIUM SCATTERING IN THE CLOSE-COUPLING APPROACH

We present results for low-energy elastic S-, P-, and D-wave phase shifts, capture and total cross sections of positron-helium scattering with different basis sets in the close coupling approach using realistic wave functions for He(1s1s), He(1s2(1)s), He(1s2(1)p) and positronium (1s) states. A resonance is found in the S-wave capture cross section at 84 eV.

Positronium-alkali-ion scattering in the close-coupling approximation

We present results for low- and medium-energy elastic and capture cross sections for positronium-atom-alkali-ion scattering using the coupled static close-coupling approximation.

LAMINAR THERMALLY DEVELOPING FLOW INSIDE RIGHT-ANGULARLY TRIANGULAR DUCTS

An analytical approach based on the generalized integral transform technique is presented, for the solution of laminar forced convection within the thermal entry region of ducts with arbitrarily shaped cross-sections. The analysis is illustrated through consideration of a right triangular duct subjected to constant wall temperature boundary condition. Critical comparisons are made with results available in the literature, from direct numerical approaches. Numerical results for dimensionless average temperature and Nusselt numbers are presented for different apex angles.

DIFFRACTION AND THE GLUON MASS

We recently proposed a QCD Pomeron described by the exchange of two nonperturbative gluons characterized by a dynamically generated gluon mass. It is shown here that data on elastic scattering, exclusive rho production in deep inelastic scattering, and the J/psi-nucleon total cross section can be successfully described in terms of a single gluon mass m(g) congruent-to 0.37 GeV. We observe that the total cross sections of hadrons with small radii, such as J/psi, have a marked dependence on the effective gluon mass.

RELATING THE QCD POMERON TO AN EFFECTIVE GLUON MASS

We construct the Pomeron as an exchange of two nonperturbative gluons, where the nonperturbative gluon propagator is described by an approximate solution of the Schwinger-Dyson equation which contains a dynamically generated gluon mass. We compute the total and elastic differential (dsigma/dt) cross sections for pp scattering, obtaining agreement with the experimental data for a gluon mass m = 370 MeV for LAMBDA(QCD) = 300 MeV. In particular, the Pomeron effectively behaves like a photon-exchange diagram with a coupling determined by the glucon mass.

Positronium scattering from ions, atoms and molecules

Elastic and inelastic scattering of positronium (Ps) by H, He, He(+) and H(2) have been studied using coupled-channel calculations with a regularised nonlocal model exchange potential. Suitability and reliability of the theoretical scheme have been demonstrated by studying scattering cross-sections in various systems and also by addressing critical dynamic features like binding and resonances of Ps to open-shell-atoms. Results are found to be in good agreement with Variational predictions and experimental observations. (C) 2000 Elsevier B.V. Ltd. All rights reserved.

Spectroscopic properties of lead fluoroborate glasses doped with ytterbium

A new lead fluoroborate glass (PbO-PbF2-B2O3) doped with ytterbium (Yb:PbFB) is presented. Samples with different concentrations of Yb3+ were produced and had their emission cross-sections, fluorescence lifetimes and minimum pump intensities determined. They have high refractive index of 2.2 and a density of 4.4 g/cm(3). For a doping level of 1.153x10(20) ions/cm(3), the fluorescence lifetime, after excitation at 968 nm, is 0.81 ms, which is comparable to Yb:tellurite laser glass. Also, an emission band at 1022 nm is measured with emission cross-section of approximately 1.07x10(-20) cm(2) and fluorescence effective linewidth of 60 nm, which is comparable to Yb:phosphate laser glass. (C) 2001 Optical Society of America.