General soliton matrices in the Riemann-Hilbert problem for integrable nonlinear equations

We derive the soliton matrices corresponding to an arbitrary number of higher-order normal zeros for the matrix Riemann-Hilbert problem of arbitrary matrix dimension, thus giving the complete solution to the problem of higher-order solitons. Our soliton matrices explicitly give all higher-order multisoliton solutions to the nonlinear partial differential equations integrable through the matrix Riemann-Hilbert problem. We have applied these general results to the three-wave interaction system, and derived new classes of higher-order soliton and two-soliton solutions, in complement to those from our previous publication [Stud. Appl. Math. 110, 297 (2003)], where only the elementary higher-order zeros were considered. The higher-order solitons corresponding to nonelementary zeros generically describe the simultaneous breakup of a pumping wave (u(3)) into the other two components (u(1) and u(2)) and merger of u(1) and u(2) waves into the pumping u(3) wave. The two-soliton solutions corresponding to two simple zeros generically describe the breakup of the pumping u(3) wave into the u(1) and u(2) components, and the reverse process. In the nongeneric cases, these two-soliton solutions could describe the elastic interaction of the u(1) and u(2) waves, thus reproducing previous results obtained by Zakharov and Manakov [Zh. Eksp. Teor. Fiz. 69, 1654 (1975)] and Kaup [Stud. Appl. Math. 55, 9 (1976)]. (C) 2003 American Institute of Physics.

The interaction between atoms of Au and Cu with clean Si(111) surface: A study combining synchrotron radiation grazing incidence X-ray fluorescence analysis and theoretical calculations

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Incidence of self-reported hearing loss and associated risk factors among the elderly in São Paulo, Brazil: the SABE survey

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The incidence of Shiga toxin-producing Escherichia coli in cattle with mastitis in Brazil

Aims: To determine the prevalence and molecular characteristics of Shiga toxin-producing Escherichia coli (STEC) isolates from bovine mastitic milk in Brazil.Methods and Results: A total of 2144 milk samples from dairy cattle showing mastitis were screened for the presence of E. coli. A total of 182 E. coli isolates were selected and examined. All were subjected to dot blot analysis using the CVD419 probe for the detection of the enterohaemolysin (hly) gene, and to a multiplex PCR for the detection of stx1, stx2 and eaeA genes. STEC were isolated from 22 (12.08%) milk samples. All the STEC isolates were tested for sensibility to 10 antimicrobials; the resistances most commonly observed were to cephalothin (86.3%), tetracycline (63.6%) and doxycycline (63.6%).Conclusion: STEC isolates were found in bovine mastitic milk in Brazil.Significance and Impact of the Study: STEC isolates from mastitic milk were potentially pathogenic for human in that they belonged to serogroups associated with diarrhoea and haemolytic-uraemic syndrome, some of them were stx2, eaeA and hly positive.

Radionuclides, heavy metals and fluorine incidence at Tapira phosphate rocks, Brazil, and their industrial (by) products

Inorganic phosphate fertilizers may contain radionuclides, heavy metals and fluorine. This paper presents the possible environmental hazards from Tapira phosphate rocks and their (by) products (Brazil) utilized as phosphate fertilizers. The activity concentration of U-238, U-234, Ra-226 and K-40 in Tapira phosphate rocks is within the world range for these rock types. The Th-232 activity concentration is higher than the mean reported in phosphate rocks. A value of 2184 nGy h(-1) was obtained for the exposure dose rate in Tapira phosphate deposit area, which is indicative of a high background radiation area. The flotation-separation process causes the incorporation of no more than 9%, 11 % and 24% of radionuclides, heavy metals and fluorine, respectively, into the phosphate concentrate. The radionuclides and heavy metals existing in phosphate fertilizers applied in Brazilian crops according to the recommended rates, do not raise their concentration in soils to harmful levels. (C) 2005 Elsevier Ltd. All rights reserved.

A method for evaluating Ra-228 in environmental matrices and its use at Pocos de Caldas plateau, Brazil

This work describes a methodology developed for performing the extraction, detection and quantification of Ra-228 in waters, suspended solids and sediments. The technique proved to be useful for analyzing samples from the hydrological environment of Morro do Ferro, Pocos de Caldas plateau, Brazil. The 228Ra activity in underground waters of 5 boreholes drilled in the area varied from 0.02 up to 14.5 Bq/l, whereas for the surficial waters the variation was from 0.04 to 0.51 Bq/l; for the suspended solids, the values ranged from 1.5 up to 419 Bq/g, whereas it was possible to find a value of 2.04 Bq/g for the sediments. These results show the applicability of the method for characterizing different matrices of environmental interest. (C) 2002 Elsevier B.V. Ltd. All rights reserved.

Grazing incidence X-ray diffraction and atomic force microscopy analysis of BaBi2Ta2O9 thin films

Thin films of BaBi2Ta2O9 (BBT) composition were prepared through the metal organic decomposition method. The crystallinity, phase formation, crystallite size and morphology of the thin films were measured as a function of the type of substrate, stoichiometry of solution and process variables such as thickness and temperature. The thin films were investigated by grazing incidence X-ray diffractometry and atomic force microscopy (AFM) techniques. For the sample without excess of bismuth, diffraction peaks other than that of the BBT phase were observed. A well crystallized BBT single phase was observed for films prepared from a solution with 10% excess of bismuth, deposited on Si/Pt substrate, with a thickness up to 150 nm and sintered at temperatures of 700 degreesC. The thin BBT phase films heat-treated at 600 degreesC presented a diffraction pattern characteristic of samples with lower degree of crystallinity whereas for the thin films heat-treated at 800 degreesC, we observed the presence of other phases than the BBT. For the thin film deposited on the Sin+ substrate, we observe that the peaks corresponding to the BBT phase are broader than that observed on the samples deposited on the Pt and Si/Pt substrates. No variation of average crystallite size was observed as the excess of Bi increased from 10 to 20%. AFM images for the samples showed that the increasing the amount of bismuth promotes grain growth. The average surface roughness measured was in the range of 16-22 nm showing that the bismuth amount had no or little effect on the roughness of films. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Immunoassays for pesticide analysis in environmental and food matrices

Immunochemical methods have increased considerably in the past years, and many examples of small and large scale studies have demonstrated the reliability of the immunotechniques for control and monitoring gf contaminant residues in different kinds of samples. Application of the immunoassay (IA) methods in pesticide residue control is an area with enormous potential for growth. The most extensively studied IA is the enzyme-linked absorbent assay (ELISA), but several other approaches, that include radioimmunoassay and immunoaffinity chromatography, have been also developed recently. In comparison with classical analytical methods, IA methods offer the possibility of highly sensitive, relatively vapid, and cost-effective measurements. This paper introduces the general IAs used until now, focusing on their use in pesticide analysis, and discussing briefly the effects of interferences from solvent residues or matrix components on the IA performance. Numerous immunochemical methods commonly used for pesticide determination in different samples such as food, crop and environmental samples are presented.

INCIDENCE OF MYCOBACTERIUM-TUBERCULOSIS AND OTHER MYCOBACTERIA ON PULMONARY INFECTIONS IN ARARAQUARA - SP, 1993

The incidence of tuberculosis and other infections by mycobacteria was analyzed in 559 patients admitted to the Tisiology Section of the Special Health Care Unit of Araraquara (SESA). Mycobacteria were isolated from 78 individuals out of this total. Among these patients, 15 were also HIV positive. The occurrence of isolated species was: M. tuberculosis: 69 patients; M. avium-intracellulare: 5 patients; M. fortuitum: 2 patients; M. chelonae: 1 patient; and M. simiae 1 patient. The latter was for the first time isolated from humans in Brazil. In most cases, non tubercular mycobacteria (NTM) were found in the HIV positive patients.

Comparison of different clean-up procedures for the determination of N-methylcarbamate insecticides in vegetable matrices by high-performance liquid chromatography with UV detection

Several clean-up procedures which included the use of glass chromatography columns (silica gel, alumina, Florisil, silanized Celite-charcoal), Sep-Pak cartridges and standard solutions were compared for the determination of the following N-methylcarbamate (NMC) insecticides: aldicarb, carbaryl, carbofuran, methomyl and propoxur. According to recovery results of the compounds after elution in a glass column, the most efficient systems employed 4.6% deactivated alumina and a silanized Celite-charcoal (4:1) as adsorbents, using dichloromethane-methanol (99:1) and toluene-acetonitrile (75:25) mixtures, respectively, as binary eluents. The recoveries of the compounds studied varied from 84 to 120%. Comparable recoveries (75-100%) for Sep-Pak cartridges in normal phase (NH2, CN) and reversed phase (C-8) were observed. Different temperatures were tested during the concentration step in a rotary evaporator, and we verified a strong influence of this parameter on the stability of some compounds, such as carbofuran and carbaryl. Recovery studies employing the best clean up procedures were performed at the Brazilian agricultural level in potato and carrot samples; Validation methodology of the US Food and Drug Administration was adapted for the N-methylcarbamate analysis. Their recoveries ranged between 79 and 93% with coefficients of variation of 2.3-8%. (C) 1998 Elsevier B.V. B.V.

POPULATION-BASED INCIDENCE OF IDDM IN THE STATE OF SAO-PAULO, BRAZIL

OBJECTIVE- To study the incidence of IDDM among children, infants to 14 yr of age, in the state of São Paulo, Brazil, 1987-1991.RESEARCH DESIGN AND METHODS - A prospective population-based register was established, using physician reports of newly diagnosed IDDM patients < 15 yr of age as the primary source of case identification and school surveys as the main secondary source. Data were collected according to the methods recommended by the Diabetes Epidemiology Research International group.RESULTS - Case ascertainment was estimated at 95.0, 92.8, and 98.8% complete for each of the three cities studied. The average annual IDDM incidence was 7.6/100,000 inhabitants (95% confidence interval, 5.6-9.7). We found a higher incidence rate in girls than boys.CONCLUSIONS - the incidence of childhood IDDM in a tropical region in South America (São Paulo, Brazil) is in the middle incidence range observed in developed countries throughout the world. Increased incidence of IDDM in girls compared with boys will be tested by the ongoing Brazilian incidence study being developed in 18 other centers across the country.