2,111 research outputs found
Bandwidth aspects in second generation current conveyors
This paper discusses bandwidth problems associated with second-generation current conveyors (CCII). In particular, our work is centered in high-capacitance applications, and has been oriented for wireless optical links and applied physics. We discuss techniques for improving bandwidth in these CCIIs, and develop a new CCII structure with larger bandwidth than traditional circuits. These circuits are then compared in terms of their noise and dynamic range characteristics. A test circuit was developed to verify these different bandwidth behaviors
Paper-based Mixed Reality Sketch Augmentation as a Conceptual Design Support Tool
This undergraduate student paper explores usage of mixed reality techniques as support tools for conceptual design. A proof-of-concept was developed to illustrate this principle. Using this as an example, a small group of designers was interviewed to determine their views on the use of this technology. These interviews are the main contribution of this paper. Several interesting applications were determined, suggesting possible usage in a wide range of domains. Paper-based sketching, mixed reality and sketch augmentation techniques complement each other, and the combination results in a highly intuitive interface
Stochastic Description of Agglomeration and Growth Processes in Glasses
We show how growth by agglomeration can be described by means of algebraic or
differential equations which determine the evolution of probabilities of
various local configurations. The minimal fluctuation condition is used to
define vitrification. Our methods have been successfully used for the
description of glass formation.Comment: 9 pages, 1 figure, LaTeX 2e, uses ws-ijmpb.cls ; submitted to
International Journal of Modern Physics
Spatially Variable Reaction In The Formation Of Anodically Grown Porous Silicon Structures
In porous silicon formations there is an increase of dissolution rate at the fluorine-covered sites of the silicon surface due to the presence of excess electrons coming from oxidation of molecular hydrogen at the passivated (hydrogen-covered) sites. The dissolution rate increase in the presence of excess charge at the fluorine-covered sites is experimentally measured and a theoretical investigation is carried out by a semiempirical Hartree-Fock calculation. This spatially variable dissolution generates the porous silicon surface. © 1995 American Institute of Physics.78159059
Camperdown Hemoglobin Associated With ÎČ° Thalassemia In A Brazilian Child
We report the coexistence of Hb Camperdown [ÎČ 104 (G6) Arg â Ser] and ÎČ°-thalassemia [ÎČ39 (Gln â stop codon)] in a nine-month-old Brazilian boy. He had a relatively more severe hypochromic and microcytic anemia in comparison to his mother's ÎČ-thalassemia trait. His Hb Camperdown heterozygous father was clinically and hematologically normal. To our knowledge, this is the first description of an association of ÎČ°-thalassemia with Hb Camperdown. Copyright by the Brazilian Society of Genetics.283394396AraĂșjo, A.S., Silva, W.A., Leao, S.A., Bandeira, F.C., Petrou, M., Modell, B., Zago, M.A., A different molecular pattern of ÎČ-thalassemia mutations in Northeast of Brazil (2003) Hemoglobin, 27, pp. 211-217Amone, A., X-ray diffraction study of binding of 2,3-diphosphoglycerate to human deoxyhemoglobin (1972) Nature, 237, pp. 146-149Bertuzzo, C.S., Sonati, M.F., Costa, F.F., Hematological phenotype and the type of ÎČ thalassemia mutation in Brazil (1997) Braz J Genet, 20, pp. 319-321Bianco, I., Graziani, B., Carboni, C., Genetic patterns in thalassemia intermedia (constitutional microcytic anemia). Familial hematological and biosynthetic studies (1977) Hum Hered, 27, pp. 257-272Blouquit, Y., Lacombe, C., Arous, N., Le Qurrec, A., Branconnier, F., Bonhomme, J., Soummer, A.M., Galacteros, F., Seven new cases of hemoglobin Camperdown alpha 2 beta 2 104 (G6) ARG â SER found in Malta, Sicily and Tunisia (1984) Hemoglobin, 8, pp. 613-619Chang, J.C., Kan, Y.W., ÎČ°-thalassemia, a nonsense mutation in man (1979) Proc Natl Acad Sci USA, 76, pp. 2886-2889Clarke, G.M., Higgins, T.N., Laboratory investigation of hemoglobinopathies and thalassemias: Review and update (2000) Clin Chem, 46, pp. 1284-1290Fonseca, S.F., Kerbauy, J., Escrivçao, C., Figueiredo, M.S., Cançado, R., Arruda, V.R., Saad, S.T.O., Costa, F.F., Genetic analysis of beta-thalassemia major and beta-thalassemia intermedia in Brazil (1998) Hemoglobin, 22, pp. 197-207Grignoli, C.R.E., Carvalho, M.H., Kimura, E.M., Sonati, M.F., Arruda, V.R., Saad, S.T.O., Costa, F.F., ÎČ°-thalassemia resulting from a novel mutation: ÎČ66/u â stop codon (2000) Eur J Haematol, 64, pp. 137-138Kimura, E.M., Grignoli, C.R.E., Pinheiro, V.R.P., Costa, F.F., Sonati, M.F., Thalassemia intermedia as a result of heterozygosis for ÎČ°-thallassemia and αααanti3.7/αα genotype in a Brazilian patient (2003) Braz J Med Biol Res, 36, pp. 699-701Kister, J., Barbadjian, J., Blouquit, Y., Bohn, B., Galacteros, F., Poyart, C., Inhibition of oxygen-linked anion binding in Hb Camperdown [α2ÎČ2 104 (G6) ARG â SER] (1989) Hemoglobin, 13, pp. 567-578Miranda, S.R.P., Kimura, E.M., Teixeira, R.C., Bertuzzo, C.S., Ramalho, A.A., Saad, S.T.O., Costa, F.F., Hb Camperdown [α2ÎČ2 104 (G6) ARG â SER] identified by DNA analysis in a Brazilian family (1996) Hemoglobin, 20, pp. 147-153Old, J.M., Screening arid genetic diagnosis of haemoglobin disorders (2003) Blood Rev, 17, pp. 43-53Olivieri, N.F., The ÎČ-thalassemias (1999) N Engl J Med, 341, pp. 99-109Thein, S.L., Genetic insights into the clinical diversity of beta thalassaemia (2004) Br J Haematol, 124, pp. 264-274Weatherall, D.J., Clegg, J.B., Inherited haemoglobin disorders: An increasing global health problem (2001) Bull World Health Organ, 79, pp. 704-712Wilkinson, T., Chua, C.G., Carrell, R.W., Robin, H., Exner, T., Lee, K.M., Kronenberg, H., Haemoglobin Camperdown ÎČ 104(G6) Arginine leads to serine (1975) Biochim Biophys Acta, 393, pp. 195-200Zago, M.A., Costa, F.F., Hereditary hemoglobin disorders in Brazil (1985) Trans R Soc Trop Med Hyg, 79, pp. 385-38
Tributyltin in crustacean tissues: Analytical performance and validation of method
The hermit crab Clibanarius vittatus is a typical organism from intertidal regions being considered as a good bioindicator of tributyltin presence at these environments. Thus this study presents the analytical performance and validation method for TBT quantification in tissues of C. vittatus by gas chromatography with pulsed flame photometric detector (GC-PFPD) after extraction with an apolar solvent (toluene) and Grignard derivatization. The limits of detection of the method (LOD) were 2.0 and 2.8 ng g -1 for TBT and DBT (dibutyltin), respectively, and its limits of quantification (LOQ) were 6.6 and 8.9 ng g-1 for TBT and DBT, respectively. The method was applied to samples from Santos Estuary, SĂŁo Paulo State, Brazil. TBT and DBT concentrations ranged from 26.7 to 175.0 ng g -1 and from 46.2 to 156.0 ng g -1, respectively. These concentrations are worrisome since toxic effects (such as endocrine disruption) have been reported for other organisms even under lower levels of registred at this study. © 2012 Sociedade Brasileira de QuĂmica
Enhancement of antibiotic activity by Cordia verbenacea DC
Escherichia coli is known to produce enterotoxins whose properties and its role in diarrheal disease has been extensively investigated. Some species of Staphylococcus are often recognized as etiological agents of many animal and human opportunistic infections. This study is the first test of change in resistance of antibiotic activity by Cordia verbenacea DC. against multiresistant strains of Escherichia coli and Staphylococcus aureus. In this study, the hexane and methanol extract of Cordia verbenacea DC. were tested for antibacterial activity alone and in combination with aminoglycosides against bacterial strains. The synergy of the methanolic and hexane were verified by microdilution method. A synergistic effect of both extracts combined with the aminoglycosides was demonstrated. It is therefore suggested that the extracts from Cordia verbenacea DC. could be used as a source of natural products derived from this plant with resistance-modifying antibacterial activity, providing a new weapon against the problem of bacterial resistance to antibiotics.Colegio de Farmacéuticos de la Provincia de Buenos Aire
Enhancement of antibiotic activity by Cordia verbenacea DC
Escherichia coli is known to produce enterotoxins whose properties and its role in diarrheal disease has been extensively investigated. Some species of Staphylococcus are often recognized as etiological agents of many animal and human opportunistic infections. This study is the first test of change in resistance of antibiotic activity by Cordia verbenacea DC. against multiresistant strains of Escherichia coli and Staphylococcus aureus. In this study, the hexane and methanol extract of Cordia verbenacea DC. were tested for antibacterial activity alone and in combination with aminoglycosides against bacterial strains. The synergy of the methanolic and hexane were verified by microdilution method. A synergistic effect of both extracts combined with the aminoglycosides was demonstrated. It is therefore suggested that the extracts from Cordia verbenacea DC. could be used as a source of natural products derived from this plant with resistance-modifying antibacterial activity, providing a new weapon against the problem of bacterial resistance to antibiotics.Colegio de Farmacéuticos de la Provincia de Buenos Aire
Frequency and damping of hydrodynamic modes in a trapped Bose-condensed gas
Recently it was shown that the Landau-Khalatnikov two-fluid hydrodynamics
describes the collision-dominated region of a trapped Bose condensate
interacting with a thermal cloud. We use these equations to discuss the low
frequency hydrodynamic collective modes in a trapped Bose gas at finite
temperatures. We derive a variational expressions based on these equations for
both the frequency and damping of collective modes. A new feature is our use of
frequency-dependent transport coefficients, which produce a natural cutoff by
eliminating the collisionless low-density tail of the thermal cloud. Above the
superfluid transition, our expression for the damping in trapped inhomogeneous
gases is analogous to the result first obtained by Landau and Lifshitz for
uniform classical fluids. We also use the moment method to discuss the
crossover from the collisionless to the hydrodynamic region. Recent data for
the monopole-quadrupole mode in the hydrodynamic region of a trapped gas of
metastable He is discussed. We also present calculations for the damping of
the analogous monopole-quadrupole condensate mode in the superfluid
phase.Comment: 22 pages, 10 figures, submitted to Physical Review
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