Dynamics of ultra-thin polystyrene with and without a (artificial) dead layer studied by resonance enhanced dynamic light scattering.

Using non-invasive, marker-free resonance enhanced dynamic light scattering, the dynamics of capillary waves on ultrathin polystyrene films' coupling to the viscoelastic and mechanical properties have been studied. The dynamics of ultrathin polymer films is still debated. In particular the question of what influence either the solid substrate and/or the fluid-gas interface has on the dynamics and the mechanical properties of films of glass forming liquids as polymers is in the focus of the present research. As a consequence, e.g., viscosity close to interfaces and thus the average viscosity of very thin films are prone to change. This study is focused on atactic, non-entangled polystyrene thin films on the gold surface. A slow dynamic mode was observed with Vogel-Fulcher-Tammann temperature dependence, slowing down with decreasing film thickness. We tentatively attribute this relaxation mode to overdamped capillary waves because of its temperature dependence and the dispersion with a wave vector which was found. No signs of a more mobile layer at the air/polymer interface or of a "dead layer" at the solid/polymer interface were found. Therefore we investigated the influence of an artificially created dead layer on the capillary wave dynamics by introducing covalently bound polystyrene polymer brushes as anchors. The dynamics was slowed down to a degree more than expected from theoretical work on the increase of density close to the solid liquid interface-instead of a "dead layer" of 2 nm, the interaction seems to extend more than 10 nm into the polymer.

Natural enamel caries: a comparative histological study on biochemical volumes.

This study aimed to test the hypothesis that organic volume is the main variable for explaining the optical properties and predictive degree of diffusion of enamel histological points at zones of natural enamel caries (NEC; surface layer, SL, n = 30, and body of the lesion, BL, n = 58) and normal enamel (NE, n = 131). Molars with either NEC or NE were quantitatively analyzed regarding the mineral, organic and water volumes (considered as effective pore volume), opacity (predicted in 94% of cases by water volume in NEC), and water volume more easily available for diffusion, αd (squared water volume divided by the nonmineral volume; related to permeability). NEC presented lower mineral volumes and higher organic volumes, effective pore volume and opacity than NE. External origin of organic volume in NEC was evidenced by an organic gradient decreasing from the surface inward (R2 = -0.7), which was not detected in teeth with NE only; αd values of the SL and NE were similar and both were lower (p < 0.0001) than that of the BL. Comparing the SL from both NEC and artificial enamel caries (AEC; published data; n = 71), with similar mineral volumes, against developing enamel (published data), AEC showed more effective pore volume (3 times higher), higher αd and opacity than NEC mainly due to differences in organic volumes. Our results reasonably matched widely known features of NEC histological zones, and confirmed the organic volume as the main variable for explaining optical properties and αd (related to permeability).

One- and two-photon quantum interferences in parametric four-wave mixing.

We report the observation of the interferometric response in parametric four-wave mixing in rubidium atoms excited by a pair of ultrashort pulses. For pulses with orthogonal polarizations and in the presence of the two-photon transition 5S-5D reveals a one-photon quantum interference, in contrast to the optical interference observed when the pulses have parallel polarization. For opposite circular polarizations no interference is observed in the fluorescence of the two-photon transition, in contrast to the one- and two-photon interferences exhibited in the nonlinear process.

Dental enamel birefringence for a wide mineral content range and for different immersion media's refractive indexes: an improved mathematical interpretation.

The aim of this study is to extend, for a larger range of mineral volume (V(1)) and different aqueous immersion media, the model for calculating the refractive index of the non-mineral phase of the human dental enamel proposed by Sousa et al. Published experimental birefringence data of carious and developing human enamel in air and aqueous immersion media with different refractive indexes were interpreted. For 48%

Penetrance of adrenocortical tumours associated with the germline TP53 R337H mutation.

BACKGROUND: An inherited germline P53 mutation has been identified in cases of childhood adrenocortical carcinoma (ACT), a neoplasm with a high incidence in southern Brazil. The penetrance of ACT in carriers of the point mutation, which encodes an arginine-to-histidine substitution at codon 337 of TP53 (R337H), has not been determined. OBJECTIVE: To investigate the penetrance of childhood ACT in carriers of the R337H TP53 mutation. METHODS: The family histories of 30 kindreds of 41 southern Brazilian children with ACT were obtained. A PCR based assay was used to detect this P53 mutation in a large number of relatives of children with ACT. In all, 927 individuals were tested for the mutation, 232 from the non-carrier and 695 (including the 40 probands) from the carrier parental lines. RESULTS: 40 children with ACT carried the TP53 R337H mutation; the remaining child with ACT was not tested. There was no evidence of Li-Fraumeni syndrome in any of the kindreds; however, seven met the criteria for Li-Fraumeni-like syndrome. The carrier parental line was identified in each kindred. Of the 695 individuals tested in the carrier parental line, 240 (34.5%) were positive for the mutation, while none of the 232 individuals in the other parental line carried the mutation. The penetrance of ACT was 9.9% (95% confidence interval, 8.7% to 11.1%). CONCLUSIONS: The TP53 R337H mutation dramatically increases predisposition to childhood ACT but not to other cancers, and explains the increased frequency of ACT observed in this geographic region.

Gastrointestinal parasitic worms in equines in the Paraíba Valley, State of São Paulo, Brazil.

Over a period of 12 years, from 1988 to 2000, a total of 20 individual equines (16 horses and 4 mules) were selected at random, from 10 municipalities in the Paraíba Valley, in the State of São Paulo, Brazil, and then subjected to necropsy for collection of gastrointestinal worms. Individual samples of 10% of the intestinal contents were also taken for counting and identifying the species present, and to establish the prevalence of worms in equine species in the Paraíba Valley. In the sample considered, the presence of parasites ranged from 155 to 1249 worms. Tapeworms (Cestoidea) were present in about 85% of the animals studied, and roundworms (Nematoda) in 100% of the individuals. All the tapeworms collected were of one single species, Anoplocephala perfoliata. In the case of the roundworms, the prevalence of individual species was: 100% for Cyathostomineae, 90% for Oxyuris equi, 70% for Strongylus vulgaris, 45% for S. edentatus, 15% for Strongylus equinus, 60% for Triodontophorus sp., 50% for Gyalocephalus capitatus, 15% for Oesophagodontus robustus and Craterostomum acuticaudatum, and 5% each for Parascaris equorum, Probstimayria vivipara, Habronema muscae, and Trichostrongylus axei. No specimens of flukes (Trematoda) were found in any of the animals studied.

[Visceral larva migrans: a mixed form of presentation in an adult. The clinical and laboratory aspects]. / Larva migrans visceral: forma mista de apresentação em adulto. Aspectos clínicos e laboratoriais.

We relate a case of an 18-year-old man, resident of Xapuri (state of Acre, Brazil), with a history of repeated episodes of meningoencephalitis (three in one year), each one was examined by a local doctor. In our service (Emílio Ribas Institute of Infectology) we observed a patient with polyjoint aches, radiological and bronchoscopic pulmonary alterations (without clinical features), meningeal and brain stem manifestations--with normal brain computed tomography and cerebrospinal fluid. Blood eosinophils and serological Toxocara canis test (ELISA) were greatly increased. With the hypothesis of Toxocariasis (visceral larva migrans) we administered thiabendazole that brought complete clinical and laboratory remission. Inspite of a new episode of headache with meningeal manifestation approximately one month later (treated with dexamethasone resulting in a full remission after three days) we have not found other manifestations in approximately three and a half years of ambulatory care.

Contribution of the Ogawa-Kudoh swab culture method to the diagnosis of pulmonary tuberculosis in Brazil.

OBJECTIVE: To analyse the contribution of the Ogawa-Kudoh (O-K) swab culture method to the diagnosis of pulmonary tuberculosis (PTB) in four different regions of Brazil. DESIGN: This study was carried out in two phases. Phase 1 was designed to compare the direct swab culture method (O-K) with the culture concentrated method (N-acetyl-L-cysteine-sodium hydroxide [NALC-NaOH]); for this purpose, 569 sputum samples were cultured by both methods. Phase 2 was carried out to assess the contribution of the O-K method to the diagnosis of PTB in four different regions in Brazil, based on the evaluation of 19,163 sputum samples. RESULTS: In the first phase of the study, O-K culture had a sensitivity of 94.8% and specificity of 99.8% in cases confirmed by NALC-NaOH/Löwenstein-Jensen (LJ) culture. In the second phase of the study, the overall contribution of O-K culture compared to acid-fast bacilli (AFB) examination (AFB-/culture+) to the diagnosis of PTB was 29.8%. CONCLUSION: O-K culture contributes significantly to the diagnosis of smear-negative PTB. Importantly, this method allows the recovery of clinical isolates in areas where use of the standard culture centrifuge is impossible, indicating that the O-K swab culture method should become a standard method for TB diagnosis in these regions.

Caracterização morfométrica de fêmeas, garanhões e castrados da raça Campolina baseada em índices / Morphometric characterization of Campolina mares, stallions and gelded horses using indexes

O presente estudo objetivou avaliar os índices morfométricos para garanhões, machos castrados e fêmeas da raça Campolina, bem como caracterizá-los morfologicamente. Para tanto, foram utilizadas as medidas lineares de 4.840 garanhões, 19.037 fêmeas e 1.371 machos castrados, obtidas no banco de dados do Serviço de Registro Genealógico da ABCCCampolina, com base nas quais nove índices morfométricos foram calculados utilizando-se seis medidas lineares. A análise de variância foi realizada para avaliar o efeito do sexo e da idade sobre os índices obtidos. Verificou-se que ambos os fatores influenciaram os índices morfométricos. Garanhões apresentaram peso calculado aproximado superior tanto às fêmeas quanto aos machos castrados. De acordo com o índice peitoral, todas as categorias foram classificadas como "longe do chão". Em relação aos valores médios dos índices corporal e dáctilo torácico, garanhões e castrados foram classificados como mediolíneos e eumétricos, respectivamente, enquanto as fêmeas foram classificadas como brevilíneas e hipométricas. Conclui-se que os machos castrados e os garanhões da raça Campolina enquadram-se no padrão da raça para animais tipo sela, mas as fêmeas não. Entretanto, os índices de compacidade 1 e 2 apresentam resultados contraditórios e precisam ser melhor avaliados para fins de uso em classificações. Para a maioria dos índices, os animais castrados apresentaram-se melhor proporcionados que as demais categorias.

The present study aimed to evaluate the morphometric indexes for Campolina stallions, gelded and mare horses, as well as morphologically characterizing them. For this purpose linear measurements from 4.840 stallions, 19.037 mares and 1371 gelded horses were used, obtained from ABCCCampolina's stud book database, from which nine morphometric indexes were calculated from six linear measurements. Analysis of variance was carried out to evaluate the effect of sex and age on the indexes obtained. We found that both factors influenced the morphometric index. Stallions have presented higher estimate body weight values than mares and gelded horses. According to the pectoral index values all categories were classified as far from the ground. According to body index and dactyl thoracic index average values, stallions and gelded horses were classified as medium lined and middleweight, respectively, once the mares were classified as more compact and overweight. It is concluded that Campolina stallions and gelded horses fall within the breed standard for saddle animals, but mares don't. However, the compact indexes 1 and 2 showed contradictory results and need to be better evaluated for its intended use in classifications. For most indexes gelded animals showed better proportion than the other categories.

A new approach for improving the birefringence analysis of dental enamel mineral content using polarizing microscopy.

The main problem in interpreting birefringence of dental enamel under polarizing microscopy is the lack of physical constants able to allow the Wiener equation to be applied directly to the composition of such tissue. The present study introduces a new approach to circumvent this constraint. Because the nonmineral phase of enamel is heterogeneous, its refractive index can be computed in terms of its components (namely, water, which is partially replaced by the immersion medium, and organic matter), thereby providing a more acceptable refractive index to be used in the Wiener equation. Furthermore, the enamel mineral volume is ordinarily calculated on the basis of the density 3.15 g cm(-3). The density 2.99 g cm(-3) has been, however, reported to be more accurate for enamel hydroxyapatite, so enamel mineral volumes from selected published data were converted using such a density. The birefringence of mature enamel computed by the Wiener equation, taking into account the above refinements, matched, for the first time, published experimental birefringence values. The theoretical water and organic contents were also consistent with published experimental data. Thus, a direct application of the Wiener equation to the enamel composition has now been achieved. It is speculated that quantitative data on the mineral, the water and the organic contents of mature dental enamel can be derived from interpretation of birefringence in two immersion media (obtained before and after extraction of the organic matter) with this new approach.

Influence of propagation and external phase in sequential two-photon absorption of femtosecond pulses.

We study the influence of shaping the phase of the optical field when time-delayed femtosecond pulse pairs excite a sequential two-photon transition in rubidium atoms. Propagation through this optically dense medium modifies the pulse profile. When an external phase is introduced into one of the pulses, partial cancellation of the two-photon absorption signal is observed for temporal delays much greater than the pulse duration. This behavior is qualitatively explained in terms of a negative group delay.

Quantum interference in atomic vapor observed by four-wave mixing with incoherent light.

Pairs of pulses from an incoherent source are used to investigate the time-resolved four-wave mixing response of atomic rubidium when a two-photon resonance is involved in the nonlinear process. By varying the relative polarization of the pulse pairs, we are able to select the quantum pathways and clearly distinguish optical and quantum interferences.

Temporal coherent control of a sequential transition in rubidium atoms.

An experimental investigation of the coherent interaction of femtosecond pulses with two resonant sequential transitions of Rb atoms is presented. Fluorescence from the atomic system exhibits beating at a frequency given by difference in the sequential atomic transitions. The results are interpreted in terms of quantum interference in the induced coherence and its interaction with the field that results from a cooperative emission process.

Detection of antiviral and antitumoral fractions of Chenopodium amaranticolor leaf extract.

Based on the fact that Chenopodium amaranticolor extracts showed inhibitory activity against tobacco mosaic virus (TMV) and Ehrlich tumour (EA), tests were carried out to investigate whether the antiviral and antitumoral activity were caused by the same compounds. When the extract was purified by CM Sephadex C-25 column, after precipitation with 90% ammonium sulphate, twenty active fractions against TMV and two pools of fractions active against EA were obtained. Only one fraction with high absorbance values at 260 and 280 nm was able to inhibit both TMV and EA. When the extract was purified by Bio Gel P-60 column two active fractions against TMV and EA were obtained, suggesting that they were contained in the 0.01 M fraction of the CM Sephadex column. It is suggested that C. amaranticolor leaf extract contained at least two protein-like substances manifesting antiviral and antitumoral activity.

Diode laser mode selection using a long external cavity.

We describe a simple and practical scheme to control the operation of a diode laser in a specific longitudinal mode through the use of a long external cavity. We show that for a fixed laser current and temperature, the laser can selectively oscillate in several different modes by controlling the external-cavity length. With a simultaneous sweep of the laser current and the cavity length, the laser frequency can be continuously scanned by more than 10 GHz. This laser system has been used successfully in a laser cooling experiment of neutral atoms.

Two- and four-beam magneto-optical trapping of neutral atoms.

We report the experimental realization of new stable three-dimensional schemes for trapping neutral cesium atoms in a vapor cell that use either two or four Gaussian laser beams. Probe-beam absorption is employed to characterize both types of trap, and densities of 2 x 10(8) and 1 x 10(10) cm(-3), respectively, are measured for the two-and four-beam traps. The two-beam trapping mechanism combines a longitudinal magneto-optical force with a transverse spontaneous radiation pressure force associated basically with the beam geometry. This theoretical analysis compares well with our experimental observations.

MYCN gene amplification. Identification of cell populations containing double minutes and homogeneously staining regions in neuroblastoma tumors.

Neuroblastoma is the second most common solid tumor occurring in children. Amplification of the MYCN oncogene is associated with poor prognosis. To identify neuroblastoma tumors with MYCN amplification, we studied the number of copies of MYCN in interphase cells by fluorescence in situ hybridization in 20 neuroblastoma patients. MYCN amplification appeared in 7 tumor specimens. Interphase and metaphase studies showed a tumor cell population with both forms of amplification, double minutes and homogeneously staining regions, in two patients. These patients showed a smaller tumor cell subpopulation with the presence of more than one homogeneously staining region, suggesting that gene amplification was undergoing karyotype evolution.

Aspectos do ciclo biologico do eurytrema coelomaticum (trematoda: dicrocoeliidae) no molusco bradybaena similaris (gastropoda) / Aspects of the life cucle of eurytrema coelomaticum (trematoda: dicrocoeliidae) no molusco bradybaena similaris (gastropoda)

The life of Eurytrema coelomaticum was studied in the snails Bradybaena similaris with the following objetive to analize the development and prevalence of the trematode within its intermediate hosts. The study was happened about laboratory and natural observations at two municipalities localized at Vale do Paraiba, SP, Brazil. The prevalence of E. coelomaticum in B. similaris at the properties surveyed ranged between 9.75 percent and 20.15 percent at Lorena and Pindamonhangaba, SP, respectively

A tecnica da palma aberta na contratura de Dupuytren. / Open palm technic in Dupuytren's contracture

Os autores relatam sua experiencia no tratamento de 16 maos com enfermidade de Dupuytren. Em todos foi utilizada a tecnica da palma aberta