Pre-Hispanic ceramics analyzed using PIXE and radiographic techniques

Ceramics objects are the most common artifacts found during excavation of archaeological sites and often depicts cultural habits and manufacturing technologies of the culture. The determination of macroscopic and microscopic characteristics of the ceramic objects such as the ceramic porosity, addition of tempers in the clay, main chemical components and the trace elements present in the ceramic can reveal many aspects about the manufacturing processes used by the culture, its degree of development, the provenance of the raw materials and the exchange networks. Also the radiography can help to investigate the manufactured processes, the size of the tempers used and the conservation status of the artifacts. In this present work two non-destructive techniques, radiography and PIXE (Particle Induced X-ray Emission) were used to characterize one set of thirty-six pre-Hispanic ceramic pieces from the Chimu Culture conserved in the Museu de Arqueologia e Etnologia (MAE/USP). The PIXE analyses performed in the external beam setup at LAMFI (Laboratório de Análise de Materiais por Feixes Iônicos) allowed measure the principal chemical elements such as Al, Si, K, Ti, Fe and Ca, present in this group of pieces. X-ray imagings allowed identify the manufacture processes, the granularity of the tempers used, as well as the similarity and the differences between the pieces studied.     

On reactive routing protocols in ZigBee wireless sensor networks

ZigBee is the primary standard solution for wireless sensor networks, implementing the Ad hoc On‐Demand Distance Vector (AODV) protocol in the network layer and supported by the standard IEEE 802.15.4. This study is focused on mesh topologies and the critical problems encountered when AODV is executed in conjunction with the Carrier Sense Multiple Access with Collision Avoidance protocol. These problems are mainly related to the packet overhead required to carry out route creation. To perform preliminary experiments to be able to implement AODV in a real network, a new metric is proposed herein. This metric uses fuzzy logic to help in the decision‐making process. The objective of the fuzzy routine is to determine, during the route‐discovery process, the best node to forward request/reply packets, with the aim of reducing packet overhead and energy consumption. Moreover, minor changes are also added to the discovery procedure of AODV to improve the performance of the route‐creation process. This intelligent version of AODV has provided promising experimental results, greatly reducing the number of packets required, with the consequent energy saving while selecting the best nodes to be part of the routes.     

Serum bile acids and ursodeoxycholic acid treatment in cystic fibrosis-related liver disease

Increased circulating levels of hepatotoxic bile acids may contribute to the cholestasis characteristic of cystic fibrosis-related liver disease. The aims of this study were to compare serum bile acid profiles in patients with cystic fibrosis with and without liver disease, and to evaluate the effect of treatment with ursodeoxycholic acid, a non-hepatotoxic bile acid, on liver biochemistry and serum bile acids in patients with cystic fibrosis-related liver disease. Fasting and postprandial serum bile acid levels were analysed in 15 patients (nine males; median age 18 years) with cystic fibrosis-related liver disease and compared with serum bile acid levels in 18 cystic fibrosis patients (12 males; median age 22 years) without liver disease and 10 control subjects. Fasting and postprandial serum levels of primary and secondary serum bile acids were analysed using high-performance liquid chromatography. Liver biochemistry and serum bile acids were measured in six cystic fibrosis patients with liver disease before and 6 months after treatment with ursodeoxycholic acid 20 mg/kg/day and compared with six control patients with cystic fibrosis-related liver disease. Total fasting and postprandial serum bile acid levels were significantly (P < 0.01) elevated in patients with liver disease compared to those without liver disease and controls. The fasting glycine conjugates of cholic acid, chenodeoxycholic acid and deoxycholic acid, and the fasting and postprandial taurine conjugates of cholic acid and chenodeoxycholic acid were significantly (P < 0.05) elevated in liver disease patients compared to patients without liver disease and controls. After 6 months' treatment with ursodeoxycholic acid, although the serum was significantly saturated with ursodeoxycholic acid and significant improvements in liver biochemistry were observed in the treatment group, there was no significant reduction in the levels of individual serum bile acids. Although circulating levels of potentially hepatotoxic serum bile acids are elevated in patients with cystic fibrosis-related liver disease, improvements in liver biochemistry associated with ursodeoxycholic acid treatment cannot be attributed solely to alterations in levels of endogenous bile acids.     

A three-level converter and its applicationto power factor correction

The first part of this paper introduces a novel three-level dc-dc converter topology. It is shown that a floating capacitor connected across the clamping diodes of a conventional three-level converter enables phase-shift control while retaining zero voltage switching. Design constraints and experimental results are shown for a 6-kW, 100-kHz dc-dc prototype. The second part of the paper discusses the same three-level topology operated as a single-stage front-end converter. In this application, the converter realizes power factor correction and dc output voltage regulation. To ensure low harmonic distortion, the input currents are operated in discontinuous conduction mode, and the performance, including soft switching, is also verified on a 3-kW, 50-kHz ac-dc converter.     

A school-based schistosomiasis and intestinal helminthiasis control programme in Nigeria: acceptability to community members

In a population with high prevalences in schoolchildren of infection with hookworm (32.4%), Ascaris (22.9%) and Trichuris (2.5%), visible haematuria (17.9%), micro-haematuria (17%) and proteinuria (47.3%), the knowledge about transmission of schistosomiasis and acceptability of a school-based control programme were assessed. The community perceived schistosomiasis (80.6%) and intestinal helminthiasis (66.5%) as important health problems in school-age children and most people would prefer placement of the control programme in school because it would eliminate transportation cost to the health facility. They welcomed the idea of using teachers for detection of infection and drug administration. The health staff, on the other hand, were willing to work with teachers, but emphasized that teachers should be limited to organizational and supervisory roles while they do tests and administer the drug. This view was also shared by the officials in the state ministries of health and education.     

Full-wave analysis of a nonradiative dielectric waveguide with apseudochiral Ω-slab

This paper presents a new microwave device - a non-radiative dielectric (NRD) waveguide with a dielectric pseudochiral Ω-slab - the Ω-NRD waveguide. A rigorous full-wave analysis is presented and the modal equations for the longitudinal-section magnetic (LSM) and longitudinal-section electric (LSE) modes are derived. The dispersion curves and operational diagrams for the first hybrid LSM modes are presented. The effect of the pseudochiral Ω-medium is discussed. New interesting modal features are revealed, showing that the propagation characteristics may differ considerably from the common isotropic case     

Analysis of viral and cellular parameters which affect the fusion process of influenza viruses

In the present investigation we studied the fusogenic process developed by influenza A, B and C viruses on cell surfaces and different factors associated with virus and cell membrane structures. The biological activity of purified virus strains was evaluated in hemagglutination, sialidase and fusion assays. Hemolysis by influenza A, B and C viruses ranging from 77.4 to 97.2%, from 20.0 to 65.0% from 0.2 to 93.7% and from 9.0 to 76.1% was observed when human, chicken, rabbit and monkey erythrocytes, respectively, were tested at pH 5.5. At this pH, low hemolysis indexes for influenza A, B and C viruses were observed if horse erythrocytes were used as target cells for the fusion process, which could be explained by an inefficient receptor binding activity of influenza on N-glycolyl sialic acids. Differences in hemagglutinin receptor binding activity due to its specificity to N-acetyl or N-glycolyl cell surface oligosaccharides, density of these cellular receptors and level of negative charges on the cell surface may possibly explain these results, showing influence on the sialidase activity and the fusogenic process. Comparative analysis showed a lack of dependence between the sialidase and fusion activities developed by influenza B viruses. Influenza A viruses at low sialidase titers (< 2) also exhibited clearly low hemolysis at pH 5.5 (15.8%), while influenza B viruses with similarly low sialidase titers showed highly variable hemolysis indexes (0.2 to 78.0%). These results support the idea that different virus and cell-associated factors such as those presented above have a significant effect on the multifactorial fusion process.     

One of two NTP binding sites in poliovirus RNA polymerase required for RNA replication

The poliovirus RNA-dependent RNA polymerase (3Dpol) has been shown to contain two NTP binding sites by chemical cross-linking of oxidized nucleotide to the intact protein. Only one site (Lys-61) was shown to be essential for RNA chain elongation activity by purified enzyme; however, a full-length viral RNA, coding for an altered lysine residue (K276L) in the second site, generated virus with a minute plaque phenotype that rapidly reverted to a wild-type phenotype with Arg-276 replacing Leu-276 in 3D. Viruses with lysine to leucine substitutions in other positions of the second binding site of their polymerase proteins grew with wild-type phenotype. To test the significance of the second binding site, poliovirus 3Dpol was generated with lysine (wild-type), leucine, or arginine at residue 276 and tested for NTP cross-linking using 32P-oxidized GTP. Analysis of cyanogen bromide peptides of each 3D preparation showed that the second NTP binding site had severely reduced NTP binding in mu276(Leu) but not in the revertant mu276(Arg), despite the reported requirement for lysine in the cross-linking reaction. To eliminate the possibility that 32P-oxidized GTP cross-linked to Arg at residue 276, a model system was designed with unmodified amino acid or acetylated (alpha-amino) amino acid and 32P-oxidized GTP. Cross-linking to lysine, but not leucine or arginine, was observed thus eliminating the possibility that NTP could be cross-linked to residue 276 in 3D. We conclude that NTP binding at the second site in poliovirus 3D is at lysine residues at positions other than 276 (278 or 283), and nucleotide binding at these sites has no bearing on elongation activity or replication of the virus. Nucleotide binding only at the site including Lys-61 is essential for RNA replication.