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Search Results: 1 - 10 of 704392 matches for " R?mulo D. A.;Suarez "
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Nanosized and reusable SiO2/ZrO2 catalyst for highly efficient biodiesel production by soybean transesterification
Faria, Elaine A.;Marques, Jéssica S.;Dias, Ingrid M.;Andrade, Rmulo D. A.;Suarez, Paulo A. Z.;Prado, Alexandre G. S.;
Journal of the Brazilian Chemical Society , 2009, DOI: 10.1590/S0103-50532009000900023
Abstract: nanosized sio2/zro2 catalyst with high surface area (131.50 ± 14 m2 g-1) was prepared by the sol-gel method. the material presented highly homogeneous particles with an average diameter of 250 nm according to sem images. it was applied in the transesterification of soybean oil for biodiesel production. the biodiesel conversion reached a yield of 96.2 ± 1.4 % after 3 h of transesterification reaction catalised by sio2/zro2 (sizr). the catalyst was recovered and reused six times, maintaining a catalytic efficiency of about 84.1 %.
Two-Dimensional Simulation of the Navier-Stokes Equations for Laminar and Turbulent Flow around a Heated Square Cylinder with Forced Convection  [PDF]
Rmulo D. C. Santos, Sílvio M. A. Gama, Ramiro G. R. Camacho
Applied Mathematics (AM) , 2018, DOI: 10.4236/am.2018.93023
Abstract:
Few studies jointly investigate thermal and turbulent effects. In general, these subjects are treated separately. The purpose of this paper is to use the Immersed Boundary Method (IBM) coupled with the Virtual Physical Model (VPM) to investigate incompressible two-dimensional Newtonian flow around a heated square cylinder at constant temperature on its surface with forced convection and turbulence. The VPM model dynamically evaluates the force that the fluid exerts on the immersed surface and the thermal exchange between both in the Reynolds numbers (Re) window 40 ≤ Re ≤ 5×103 . For simulations of turbulence the Smagorinsky and Spalart-Allmaras models are used. The first model uses the Large Eddy Simulation (LES) methodology and is based on the local equilibrium hypothesis for small scales associated with the Boussinesq hypothesis, such that the energy injected into the spectrum of the turbulence balances the energy dissipated by convective effects. The second model uses the concept Unsteady Reynolds Averaged Navier-Stokes Equations (URANS), with only one transport equation for turbulent viscosity, being calibrated in pressure gradient layers. The goal of this work is to analyse the combination of the heat-transfer phenomena with the turbulence for the thermo-fluid-structure interaction in a square cylinder. For this, it was developed a C/C++ code that requires low computational costs in regards to memory and computer facilities. It is observed that, with the increase of the Reynolds number, an increase of the drag coefficient occurs, as well as reinforces the influence of the pressure distribution downstream of the cylinder, which is strongly influenced by the formation and detachment of vortices on the upper and lower sides of the square cylinder.
Vouchers, choice, and public policy: An overview
Rómulo A. Chumacero,Ricardo D. Paredes
Estudios de Economia , 2012,
Abstract: El sistema de vouchers tiene como pilares fundamentales a la elección informada de los padres y la competencia que esta genera para promover mejoras en la calidad. Este documento resume la evidencia reciente en la materia y discute algunas de sus implicancias de política pública.
Characterizing income distribution for poverty and inequality analysis
Rómulo A. Chumacero,Ricardo D. Paredes
Estudios de Economia , 2005,
Abstract: Este trabajo es una caracterización empírica sistemática de la distribución de ingresos en Chile. Esta caracterización permite entender la aparente paradoja por la que coexisten resultados económicos exitosos y una desigual y persistente distribución. Una característica empírica de relevancia generalmente ignorada es la de segmentación. Como un ejemplo, el trabajo muestra los potenciales efectos de políticas que pretenden disminuir la desigualdad: una que pretende incrementar la cobertura educacional (asumiendo erróneamente una población homogénea) y otra que pretende reducir la brecha en calidad de la educación (asumiendo poblaciones heterogéneas).
School choice and information
Daniel Gómez,Rómulo A. Chumacero,Ricardo D. Paredes
Estudios de Economia , 2012,
Abstract: Uno de los pilares detrás del sistema chileno de vouchers es que la competencia entre escuelas por atraer alumnos debiera conducir a mejoras en la calidad de la educación. Encuestas a padres de familia indican que los padres desconocenel desempe o de las escuelas de sus hijos. Este trabajo muestra el efecto de la provisión de información en la selección de escuelas. Para ello, construimosuna base de datos que incluye medidas de distancia entre hogares y escuelas, junto con información del desempe o de las escuelas en pruebas estandarizadas para dos períodos (1996 y 2003). Mientras que en 1996 no existía información pública del desempe o de una escuela, en el a o 2003 sí la había. Concluimos que en ambos períodos el desempe o de los colegios es importante en la elección de escuelas, por lo que los padres se comportan como si conocieran esta información. De todos modos, hacer pública esta información hizo que este factor sea más relevante al momento de elegir escuelas.
Caracterización clínica y aspectos lesionales macro y microscópicos de la leucemia linfoblástica en salmones y truchas de cultivo
CUBILLOS,V.; SUAREZ,D.; ENRIQUEZ,R.; ALBERDI,A.; MONRAS,M.;
Archivos de medicina veterinaria , 2000, DOI: 10.4067/S0301-732X2000000200009
Abstract: in order to determine the types of gross and microscopic lesions in salmonid fish with lymphoblastic leukemia in the x region, the location and degree of severity amongst the different kinds of salmonids and the relationship with the presence of the microsporidium nucleospora salmonis, were analysed in 113 o. kisutch, 100 s. salar, 89 o. mykiss and 13 o. tshawytscha. furthermore, histologically positive samples to lymphoblastic leukemia, from kidney, spleen, liver, pancreas, piloric caeca, eye, ovary and heart samples were analysed. the histological study showed 5.7% of positive cases in fishes with lymphoblastic leukemia, characterised by edged location, dark skin, and pale gills. in the atlantic salmon (s. salar), the bilateral exophthalmos and the presence of haemorrhages in the base of fins were more emphasised,. internally, the fish showed rhinomegaly and pale liver. rainbow trout (o. mykiss) showed 40.0% of splenomegaly and the atlantic salmon (s. salar) showed a 33.3% of abnormal coloration in muscle and piloric caeca. the most affected organs with lymphoblastic leukemia in all the species under study were kidney, spleen and with kidney and spleen as the principal affected organs association. microscopically, all the kidneys showed lymphoblastic cells infiltration diagnosed in 62.5% of the analysed samples. the rainbow trout (o. mykiss) showed severe tubular necrotic alterations and in the atlantic salmon (s. salar), a marked inflammatory reaction was observed. liver, spleen, pancreas, piloric caeca, eye, ovary and heart were also affected by lymphoblastic cell infiltration, with cellular and nuclear pleomorphism. on the other hand, nucleospora salmonis was detected in renal and splenic tissue in the coho salmon (o. kisutch), and in the lymphoblastic cells of the atlantic salmon (s. salar)
Caracterización clínica y aspectos lesionales macro y microscópicos de la leucemia linfoblástica en salmones y truchas de cultivo Clinic and Pathologic Characterization of the Lymphoblastic Leukemia in Culture's salmonids
V. CUBILLOS,D. SUAREZ,R. ENRIQUEZ,A. ALBERDI
Archivos de medicina veterinaria , 2000,
Abstract: Con el propósito de determinar los tipos de lesiones macro y microscópicos presentes en Salmonídeos afectados de L. Linfoblástica en la X Región (Latitud 41o20′S - 43o 35′S), de igual forma su localización y grado de severidad entre las distintas especies y relacionarlas con la presencia del microsporideo Nucleospora salmonis, se analizaron 113 O. kisutch, 100 S. salar, 89 O. mykiss y 13 O. tshawytscha. Además, se estudiaron muestras de ri ón, bazo, hígado, páncreas y ciegos pilóricos histológicamente positivas a L. Linfoblástica. Histológicamente se determinó un 5,7% de casos positivos en peces clínicamente afectados de L. Linfoblástica, caracterizándose por presentar piel oscura, ubicación orillada y palidez branquial. En el salmón del atlántico (S. salar) destacó, además la exoftalmia bilateral y la presencia de hemorragias en la base de las aletas. Internamente, los peces presentaron renomegalia y palidez hepática. La trucha arco iris (O. mykiss) presentó un 40% de esplenomegalia y el salmón del atlántico (S. salar) un 33,3% de coloración anormal en músculo y ciegos pilóricos. Los órganos más afectados con L. Linfoblástica en todas las especies estudiadas fueron ri ón, bazo e hígado, siendo la principal asociación de órganos afectados la existente entre ri ón y bazo. Microscópicamente, todos los ri ones presentaron infiltrado linfoblástico, diagnosti-cándose 62,5% de positividad en las muestras analizadas. La trucha arco iris (O. mykiss) presentó severas alteraciones necróticas tubulares y en el salmón del atlántico (S. salar) se observó marcada reacción inflamatoria. Hígado, bazo, páncreas y ciegos pilóricos también se vieron afectados por infiltrado linfoblástico, el cual evidenció pleomorfismo celular y nuclear. Por otra parte, se detectó Nucleospora salmonis en tejido renal y esplénico en el salmón coho (O. kisutch) y el salmón del atlántico (S. salar) en linfoblastos In order to determine the types of gross and microscopic lesions in Salmonid fish with Lymphoblastic Leukemia in the X Region, the location and degree of severity amongst the different kinds of Salmonids and the relationship with the presence of the microsporidium Nucleospora salmonis, were analysed in 113 O. kisutch, 100 S. salar, 89 O. mykiss and 13 O. tshawytscha. Furthermore, histologically positive samples to Lymphoblastic Leukemia, from kidney, spleen, liver, pancreas, piloric caeca, eye, ovary and heart samples were analysed. The histological study showed 5.7% of positive cases in fishes with Lymphoblastic Leukemia, characterised by edged location, dark skin, and pale gills.
Multi-Beam RF Aperture Using Multiplierless FFT Approximation
D. Suarez,R. J. Cintra,F. M. Bayer,A. Sengupta,S. Kulasekera,A. Madanayake
Statistics , 2015, DOI: 10.1049/el.2014.3561
Abstract: Multiple independent radio frequency (RF) beams find applications in communications, radio astronomy, radar, and microwave imaging. An $N$-point FFT applied spatially across an array of receiver antennas provides $N$-independent RF beams at $\frac{N}{2}\log_2N$ multiplier complexity. Here, a low-complexity multiplierless approximation for the 8-point FFT is presented for RF beamforming, using only 26 additions. The algorithm provides eight beams that closely resemble the antenna array patterns of the traditional FFT-based beamformer albeit without using multipliers. The proposed FFT-like algorithm is useful for low-power RF multi-beam receivers; being synthesized in 45 nm CMOS technology at 1.1 V supply, and verified on-chip using a Xilinx Virtex-6 Lx240T FPGA device. The CMOS simulation and FPGA implementation indicate bandwidths of 588 MHz and 369 MHz, respectively, for each of the independent receive-mode RF beams.
Multi-beam 4 GHz Microwave Apertures Using Current-Mode DFT Approximation on 65 nm CMOS
V. Ariyarathna,S. Kulasekera,A. Madanayake,D. Suarez,R. J. Cintra,F. M. Bayer,L. Belostotski
Mathematics , 2015,
Abstract: A current-mode CMOS design is proposed for realizing receive mode multi-beams in the analog domain using a novel DFT approximation. High-bandwidth CMOS RF transistors are employed in low-voltage current mirrors to achieve bandwidths exceeding 4 GHz with good beam fidelity. Current mirrors realize the coefficients of the considered DFT approximation, which take simple values in $\{0, \pm1, \pm2\}$ only. This allows high bandwidths realizations using simple circuitry without needing phase-shifters or delays. The proposed design is used as a method to efficiently achieve spatial discrete Fourier transform operation across a ULA to obtain multiple simultaneous RF beams. An example using 1.2 V current-mode approximate DFT on 65 nm CMOS, with BSIM4 models from the RF kit, show potential operation up to 4 GHz with eight independent aperture beams.
Illegal Use of Clenbuterol in Cattle Production in México  [PDF]
Benjamin Valladares-Carranza, Rómulo Ba?uelos-Valenzuela, Silvia D. Pe?a-Betancourt, Valente Velázquez-Ordo?ez, Yadira Velázquez-Armenta, Alejandro Nava-Ocampo
Health (Health) , 2014, DOI: 10.4236/health.2014.68087
Abstract: Slaughtered cattle (n = 582) from México State were bled for a serological screening of clenbuterol residues, using a commercial enzyme-linked immunosorbent assay (ELISA). Clenbuterol residues were found in a total of 153/582 (26.2%) sera analysed. These results reinforced the assumption of the illegal use of clenbuterol in cattle production in México; therefore, routine screening examinations in slaughtered cattle were strongly advised considering the toxic potential for humans.
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