The renewable energy market in Brazil: Current status and potential

Renewable energy offers a range of options with which to meet the growing demand for energy, particularly in the context of the pursuit (especially in developing countries) of economic development which takes into account social and environmental issues. Brazil has abundant natural sources of renewable energy, such as wind and solar power, hydraulic energy, small hydroelectric plants, ethanol and bio-diesel. These sources form part of the Brazilian strategy aimed at satisfying the demand for 6300 MW of fresh capacity per year arising out of projected economic growth of 5.1% per year over the next 10 years. Renewable energy sources currently provide 47.2% of the internal supply of primary energy in Brazil. Brazil has been pursuing a strategy of maintaining its renewable energy matrix and developing and providing incentives for further low carbon initiatives.In this study we set out an overview of the renewable energy options available in Brazil, their current status, the main positive results obtained to date and future potential. We describe the market for renewable energy in Brazil and examine specific public policies aimed at overcoming barriers to this market, thereby promoting its consolidation and expansion.     

Simulated annealing-based fitting of CAD models to point clouds of mechanical parts’ assemblies

Engineering with Computers - This paper introduces a new fitting approach to allow an efficient part-by-part reconstruction or update of editable CAD models fitting the point cloud of a digitized...     

Methotrexate in juvenile rheumatoid arthritis. Do the benefits outweigh the risks?

Juvenile rheumatoid arthritis (JRA) is a heterogeneous group of autoimmune diseases resulting in chronic idiopathic peripheral arthritis. The aetiology of JRA is unclear, and current pharmacotherapy is ameliorative rather than curative. Nonsteroidal anti-inflammatory drugs are given initially, but only one-third to one-fourth of patients are managed adequately with these agents. Advanced therapeutic drugs, frequently referred to as disease-modifying antirheumatic drugs or second-line agents, are given to the child with aggressive or resistant disease. Among these, the antimetabolite methotrexate has proven to be the most effective in alleviating articular disease manifestations and reducing laboratory parameters of inflammation. When given orally in low dosages (10 to 15 mg/m2/week), methotrexate is well tolerated, without evidence of substantial bone marrow suppression or severe hepatotoxicity. Extensive long term tolerability data are not yet available for children, but longitudinal studies in adult patients with rheumatoid arthritis suggest that the drug may be given safely for extended periods in many patients. Paediatric rheumatologists are beginning to give higher dosages of methotrexate (up to 1 mg/kg/week) parenterally with some success. The long term consequences of higher dose methotrexate in children are unknown. Methotrexate has now become, and will probably remain for some time, the drug of first choice for children with recalcitrant JRA.     

Early surgery in Duchenne muscular dystrophy. Experience at Istituto Ortopedico Rizzoli, Bologna, Italy

TIA is an important risk factor for ischemic stroke. Early diagnosis and management can result in a significant reduction in the risk of subsequent stroke. We report the case of a 54-year-old man who developed a 5-second episode of leg weakness and in whom a tight stenosis of the appropriate carotid artery was found. TIAs can sometimes be brief and have an atypical presentation, requiring a high level of suspicion for early diagnosis.     

Harmonic-loaded microwave power amplifiers: Nonlinear design procedure

A nonlinear design procedure for microwave power amplifiers is presented. The methodology makes use of a complete nonlinear model for the active device and an exact nonlinear analysis method. Suitable harmonic loading conditions for efficient power performance are imposed simultaneously and consistently with the analysis. The procedure is much faster than conventional repeated nonlinear analyses. © 1995 John Wiley & Sons, Inc.     

Hepatitis C virus infection in mixed cryoglobulinemia and B-cell non-Hodgkin's lymphoma: evidence for a pathogenetic role

We investigated the pathogenetic relevance of hepatitis C virus (HCV) infection in mixed cryoglobulinemia (MC) with or without complicating B-cell Non-Hodgkin's lymphoma (NHL) in comparison with other immunological and lymphoproliferative disorders. The following groups of patients were studied: A) 25 patients with MC in 7 cases evolved into B-cell NHL; B) 25 healthy subjects; C) 22 patients with different systemic immune diseases; D) 24 patients with chronic HCV infection without MC; E) 25 patients with B-cell idiopathic NHL. Methods used included: i) Polymerase chain reaction (PCR) for HCV RNA detection in serum and peripheral blood mononuclear cells (PBMC) (uncultured or mitogen-stimulated); ii) Branched DNA (b-DNA) for HCV RNA quantification; iii) HCV genotyping by genotype-specific primers localized in the core region and by hybridization of amplification products of the 5' untranslated region (5'UTR), obtained with universal primers, using genotype-specific probes. Serum anti-HCV and HCV RNA were detected in 88% and 73% of MC patients, respectively, and in a significantly lower percentage of healthy controls and patients with autoimmune diseases. HCV RNA concentration was significantly lower in supernatants than in corresponding whole sera (p < 0.001). Plus-strand HCV RNA was detected in 81% of peripheral blood mononuclear cell (PBMC) samples and minus-strand in the majority of fresh or mitogen stimulated cells. All MC patients with NHL had HCV RNA sequences in PBMC. HCV genotype 2a/III was detected in MC patients with a prevalence that was significantly higher than in HCV infected patients without MC. Surprisingly, HCV markers (anti-HCV and/or HCV RNA) were found in 32% of patients with idiopathic NHL. These data suggest that HCV infection is involved in the pathogenesis of MC through both direct participation in the immune complex related vasculitis and by triggering the lymphoproliferative disorder underlying the disease. This latter disorder seems to be related to HCV lymphotropism which could also be responsible for the evolution of MC to malignant lymphoma. This study also suggests that HCV infection may be involved in the pathogenesis of idiopathic B-cell NHL through a similar pathogenetic mechanism.     

Synthesis and characterisation of a nematic homo-polyurethane

The presence of hydrogen bonds in the chemical structure of polymers promotes and stabilises the crystalline phase. For liquid crystalline (LC) polymers, the side insertion of aliphatic units to the mesogenic unit is a suitable artifice to decrease the crystalline stability, without significantly affecting the stability of the LC phases. Here, we report on the synthesis of a LC homo-polyurethane with high hydrogen bond concentration along the chain and bearing an n-pentyl side-chain. Rheological behaviour, thermal analysis, and X-ray diffraction show that the stable LC phase is the nematic.     

Physical/electromagnetic pHEMT modeling

An effective technique, which is based only on geometrical and physical data, is presented for the analysis of high-frequency FETs. The intrinsic part of this electron device is described by a quasi-two-dimensional hydrodynamic transport model, coupled to a numerical electromagnetic field time domain solver in three dimensions that analyzes the passive part of the FET. Such an analysis is entirely performed in the time domain, thus allowing linear and nonlinear operations. The obtained data give insights to some parameters affecting the signal distribution through the entire device structure; a comprehensive discussion of these is given for a test device. In order to prove the validity of the approach, the bias-dependent small-signal analysis is compared with the corresponding measurements up to 50 GHz for two 0.3-/spl mu/m gate-length AlGaAs-InGaAs-GaAs pseudomorphic high electron-mobility transistors, each having two gate fingers of 25-/spl mu/m and 100-/spl mu/m width, at bias points ranging from Idss to the pinchoff regime. The accuracy and the efficiency of the approach make it suitable for device optimization.     

Equivalent circuit models for computer aided design of microstriprectangular structures

Microstrip rectangular structures are modeled in terms of equivalent circuits in order to overcome many of the drawbacks and limitations of previously proposed approaches and the poor accuracy still introduced by most of the presently available models. Through a successful electromagnetic approach, lumped element models for interacting and noninteracting step discontinuities have been created and tested. An alternative model is also proposed to account for shunt connected double and single stubs in cross and tee junction with the main line, respectively. The different models have been tested on the same structure to demonstrate their congruency     

A remote scanning Raman spectrometer for in situ measurements of works of art

In conservation science, one of the main concerns is to extract information from an artistic surface without damaging it. Raman spectroscopy has emerged in recent years as a reliable tool for the non-destructive analysis of a wide range of inorganic and organic materials in works of art and archaeological objects. Nevertheless, the technique is still mainly limited to the analysis of micro-samples taken from artistic surfaces. The development of an instrument able to perform non-contact analysis of an area of a few square centimeters aims to further increase the employment of this technique. This paper describes the development of a prototype Raman scanning spectrometer based on a diode laser, a 2D scanning mirror stage and a custom optical system, which can map a surface of 6 cm in diameter at a working distance of 20 cm. The device exhibits collecting optics with a depth of field close to 6 cm, which makes the Raman system suitable for the analysis of non-flat surfaces and three-dimensional objects. In addition, the overall dimensions and weight of the instrument have been limited in order to make the device transportable and, in principle, usable for in situ measurements. Details on the design of the device, with particular emphasis on the collecting optical system, and on results of the characterization tests carried out to assess its performances are reported. Finally, an example of an application involving the identification of pigments from a model painting is presented.