Exploring the potentialities of a new type of CFRP laminate for the simultaneous flexural and shear strengthening of RC beams: numerical research

This study aims to develop an innovative carbon fibre reinforced polymer (CFRP) laminate with a U configuration to address strengthening interventions, where the increment of both flexural and shear capacity of reinforced concrete (RC) elements is required. This strengthening solution combines the near surface mounted (NSM) and embedded through section (ETS) techniques in the same application, since these techniques have already evidenced high performance on flexural and shear strengthening of RC beams using FRP systems, respectively. In fact, the proposed hybrid technique aims to mobilize the advantages provided by these two strengthening techniques by using an innovative CFRP laminate. The strengthening efficacy of this new hybrid NSM/ETS technique was numerically assessed and compared to the corresponding efficiency of NSM and ETS techniques applied separately for the flexural and shear strengthening of RC beams, respectively. The numerical models are described and the main relevant results are presented and discussed.

Seasonal changes of leaf Nitrogen content in trees of Amazonian floodplains

In Amazonian floodplains the trees are exposed to extreme flooding of up to 230 days a year. Waterlogging of the roots and stems affects growth and metabolic activity of the trees. An increased leaf fall in the aquatic period and annual increment rings in the wood indicate periodical growth reductions. The present study aims at documenting seasonal changes of metabolism and vitality of adult trees in the annual cycle as expressed by changes of leaf nitrogen content. Leaves of six tree species common in floodplains in Central Amazonia and typical representants of different growth strategies were collected every month between May 1994 and June 1995 in the vicinity of Manaus, Brazil. Mean leaf nitrogen content varied between 1.3% and 3.2% in the non-flooded trees. Three species showed significantly lower Ν content in the flooded period (p=0.05, 0.001, 0.001), the difference ranging 20-25% lower than in the non-flooded period. Two species showed no significant difference while Nectandra amazonum showed 32% more Ν in the flooded season (p=0.001). Leaf nitrogen content was generally high when new leaves were flushed (in the flooded period) and decreased continuously thereafter in all species. Three species showed an additional peak of nitrogen during the first month of the terrestrial phase, in leaves which had flushed earlier, indicating that flooding may disturb nitrogen uptake.

Growth rate of a terra firme rain forest in Brazilian Amazonia over an eight-year period in response to logging

This paper deals with growth rates of trees > 5cm dbh over an eight-year period from 257 species at the Tapajós National Forest. The discussion is centred on the behaviour of the forest after logging. Permanent sample plots were established in 1981 and measured at the first time. The area was logged in 1982. Measurements after logging occurred in 1983, 1987 and 1989. Considering all species together, diameter increment was similar for both intensities of logging until five years after logging. Light-demanding species showed significantly higher growth rates than shade-tolerant species in the logged forest, with greater increment in the heavier treatment intensity. Commercial species also had higher growth rates in the heavier logged area, although those were significantly different only in the period from one to five years after logging. In the undisturbed forest, growth rates increased with increasing dbh size. At species level, growth rate varied between and within treatments, as well as between trees within species, depending mainly on degree of canopy opening. The logging favoured the growth of commercial species, chiefly the light-demanders. Therefore, if the same growth conditions continue being given, for example by silvicultural treatments, to those species of commercial interest, the forest would reach a stock available for harvesting around year 30 after logging. However, the high variation in increment rates indicates that an eight-year period is not sufficient to allow predictions on cutting cycles or polycyclic management systems for the study forest.

The morphology of the foregut of larvae and postlarva of Sesarma curacaoense De Man, 1892: a species with facultative lecithotrophy during larval development

Previous study on the resistance of larvae of Sesarma curacaoense submitted to starvation has revealed a facultative lecithotrophy during zoeal stages, but megalopa and first juvenile stages are exclusively feeding stages. In the present study, the gross morphology and fine structure of the foregut of S. curacaoense were investigated during larval, megalopa and first juvenile stages. The foregut of the zoea I show specific setae and a filter press apparently functional. The foregut undergoes changes in the zoea II (last larval stage) with increment of setae number, mainly on the cardiopyloric valve and complexity of the filter press. After metamorphosis to megalopa stage the foregut become rather complex, with a gastric mill supporting a medial and two lateral teeth well-developed. The foregut of the first juvenile is more specialized compared to the previous stage, showing similar characteristics of the decapod adults. These results provide further evidence of facultative lecithotrophic development in the larvae of S. curacaoense.

Thermal characterization of polyhydroxyalkanoates and poly(lactic acid) blends obtained by injection molding

In this work we present the thermal characterization of the full scope of polyhydroxyalcanoate and poly(lactic acid) blends obtain by injection molding. Blends of polyhydroxyalcanoate and poly(lactic acid) (PHA/PLA) were prepared in different compositions ranging from 0–100% in steps of 10%. The blends were injection molded and then characterized by differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and wide angle X-ray diffraction (WAXD). The increment of PHA fraction increased the degree of crystallinity of the blend and the miscibility of the base polymers as verified by the Fox model. The WAXD analysis indicates that the presence of PHA hindered the PLA crystallization. The crystallization evolution trough PHA weight fraction (wf) shows a phase inversion around 50-60%. SEM analyses confirmed that the miscibility of PHA/PLA blends increased with the incorporation of PHA and became total for values of PHA higher that 50%.

Short-term corneal changes with gas-permeable contact lens wear in keratoconus subjects: a comparison of two fitting approaches

Purpose: To evaluate changes in anterior corneal topography and higher-order aberrations (HOA) after 14-days of rigid gas-permeable (RGP) contact lens (CL) wear in keratoconus subjects comparing two different fitting approaches. Methods: Thirty-one keratoconus subjects (50 eyes) without previous history of CL wear were recruited for the study. Subjects were randomly fitted to either an apical-touch or three-pointtouch fitting approach. The lens’ back optic zone radius (BOZR) was 0.4 mm and 0.1 mm flatter than the first definite apical clearance lens, respectively. Differences between the baseline and post-CL wear for steepest, flattest and average corneal power (ACP) readings, central corneal astigmatism (CCA), maximum tangential curvature (KTag), anterior corneal surface asphericity, anterior corneal surface HOA and thinnest corneal thickness measured with Pentacam were compared. Results: A statistically significant flattening was found over time on the flattest and steepest simulated keratometry and ACP in apical-touch group (all p < 0.01). A statistically significant reduction in KTag was found in both groups after contact lens wear (all p < 0.05). Significant reduction was found over time in CCA (p = 0.001) and anterior corneal asphericity in both groups (p < 0.001). Thickness at the thinnest corneal point increased significantly after CL wear (p < 0.0001). Coma-like and total HOA root mean square (RMS) error were significantly reduced following CL wearing in both fitting approaches (all p < 0.05). Conclusion: Short-term rigid gas-permeable CL wear flattens the anterior cornea, increases the thinnest corneal thickness and reduces anterior surface HOA in keratoconus subjects. Apicaltouch was associated with greater corneal flattening in comparison to three-point-touch lens wear.

Evolution of the functional properties of titanium–silver thin films for biomedical applications: Influence of in-vacuum annealing

In this work, the thermal stability of TiAgx thin films, deposited by magnetron sputtering, was evaluated, envisaging their application in biomedical devices, namely as electrodes for biosignal acquisition. Based on the composition and microstructural characterization, a set of four representative TiAgx thin films was selected in order to infer whether they are thermally stable in terms of functional properties. In order to achieve this purpose, the structural and morphological evolution of the films with annealing temperature was correlated with their electrical, mechanical and thermal properties. Two distinct zones were identified and two samples from each zone were extensively analysed. In the first zone (zone I), Ti was the main component (Ti-rich zone) while in the second, zone II, the Ag content was more significant. The selected samples were annealed in vacuum at four different temperatures up to 500 oC. For the samples produced within zone I, small microstructural changes were observed due to the recrystallization of the Ti structure and grain size increment. Also, no significant changes were observed with annealing temperature regarding the f l ’ functional properties, being thermally stable up to 500 oC. For higher Ag contents (zone II) the energy supplied by thermal treatments was sufficient to activate the crystallization of Ti-Ag intermetallic phases. A strong increase of the grain size of these phases was also reported. The structural and morphological organization proved to be determinant for the physical responses of the TiAgx system. The hardness and Y g’s modulus were significantly improved with the formation of the intermetallic phases. The silver addition and annealing treatments also played an important role in the electrical conductivity of the films, which was once again improved by the formation of Ti-Ag phases. The thermal diffusivity of the films was practically unchanged with the heat-treatment. This set of results shows that this intermetallic-like thin film system has good thermal stability up to high temperatures (as high as 500 oC), which in case of the highest Ag content zone is particularly evident for electrical and mechanical properties, showing an important improvement. Hardness increases about three times, while resistivity values become half of those from the lowest Ag contents zone. These set of characteristics are consistent with the targeted applications, namely in terms of biomedical sensing devices.

A inflação pela imaginação: Estudo dos efeitos interferentes

Tese de Doutoramento em Psicologia (Especialidade de Psicologia Experimental e Ciências Cognitivas)

Implications of the Hemodynamic Optimization Approach Guided by Right Heart Catheterization in Patients with Severe Heart Failure

OBJECTIVE: To report the hemodynamic and functional responses obtained with clinical optimization guided by hemodynamic parameters in patients with severe and refractory heart failure. METHODS: Invasive hemodynamic monitoring using right heart catheterization aimed to reach low filling pressures and peripheral resistance. Frequent adjustments of intravenous diuretics and vasodilators were performed according to the hemodynamic measurements. RESULTS: We assessed 19 patients (age = 48±12 years and ejection fraction = 21±5%) with severe heart failure. The intravenous use of diuretics and vasodilators reduced by 12 mm Hg (relative reduction of 43%) pulmonary artery occlusion pressure (P<0.001), with a concomitant increment of 6 mL per beat in stroke volume (relative increment of 24%, P<0.001). We observed significant associations between pulmonary artery occlusion pressure and mean pulmonary artery pressure (r=0.76; P<0.001) and central venous pressure (r=0.63; P<0.001). After clinical optimization, improvement in functional class occurred (P< 0.001), with a tendency towards improvement in ejection fraction and no impairment to renal function. CONCLUSION: Optimization guided by hemodynamic parameters in patients with refractory heart failure provides a significant improvement in the hemodynamic profile with concomitant improvement in functional class. This study emphasizes that adjustments in blood volume result in imme-diate benefits for patients with severe heart failure.

Maneio do cão geriátrico nas 48 horas pós-cirúrgicas

Dissertação de Mestrado Integrado em Medicina Veterinária

Metabolismo de fosfolípidos, señal de calcio y sus implicancias en la diferenciación de Trypanosoma cruzi. Phospholipids metabolism, calcium signal and its implications in the differentiation of Trypanosoma cruzi.

Trypanosoma cruzi es un protozoo primitivo agente causal de la enfermedad de Chagas. La transmisión de esta enfermedad depende tanto del desarrollo y de la diferenciación del microorganismo en el intestino del vector. Las diferentes formas del parásito se han adaptado a una serie de condiciones impuestas por los distintos ambientes en donde debió habitar. Esta capacidad de sobrevivir a medios externos tan variados está dada por la diversidad en las vías de transducción de señales en el parásito. T. cruzi se multiplica y diferencia (metaciclogénesis) en el recto de los triatominos. A este nivel, los parásitos se enfrentan a un incremento en la osmolaridad causado por un elevado contenido de NaCl en la orina. En nuestro laboratorio se observó que diferentes estímulos son capaces de producir incrementos en los niveles de IP3 y de Ca2+ intracelular, consecuencia de la activación del ciclo del inositol fosfato, y activación de fosfolipasa D (PLD) y fosfatidilinositol 3 quinasa (PI3K). En un medio carente de Na+ los epimastigotes estimulados con carbacol, mostraron una señal de calcio disminuida mientras que la acumulación de IP3 no se modificó. Además, esta señal se incrementó en presencia de PMA, activador de proteína quinasa C, mientras que la acumulación de IP3 se anuló completamente. Estos resultados indujeron a pensar en un mecanismo alternativo y/o paralelo a IP3 en la liberación de Ca2+, en el cual la presencia de un intercambiador Na+/H+ favorecería la liberación del ion desde organelas acídicas. Es conocido que la señal de calcio es requerida para la metaciclogénesis, y que esta señal es independiente del Ca2+ extracelular (Lammel y col. 1996, Marchesini y col., 2002). De este modo se propone que "los epimastigotes de T. cruzi utilizan como elementos conservados a lo largo de la evolución a los elementos del ciclo del inositol fosfato, uno de los sistemas de transducción de señales más antiguo, para responder a estímulos que inducen la diferenciación del parásito". Por lo tanto, para el desarrollo de este proyecto se propone determinar la presencia de un RcIP3 en epimastigotes y conocer su compromiso en la liberación de Ca2+ desde reservorios intracelulares. Además, establecer si un intercambiador Na+/H+ en membrana de acidocalcisomas estaría relacionado con la señal de calcio intracelular y su posible regulación por proteina quinasa C y A (PKC y PKA, respectivamente). Por otro lado, para dilucidar la implicancia de estos mecanismos en el proceso de metaciclogénesis, se propone estudiar la activación del intercambiador Na+/H+ y la señal de calcio en condiciones de hiperosmolaridad, tal como ocurre en el recto del triatomino. Ademas, ya que el proceso de diferenciación involucra una reorganización de los microtubulos del citoesqueleto se pretende estudiar el compromiso del metabolismo de fosfolípidos y tubulina en procesos que contribuyen a la inducción de la metaciclogenesis. El alcance de los objetivos mencionados ayudará a dilucidar la presencia de componentes tales como RcIP3 y el intercambiador Na+/H+ involucrados en la señalización del ion bivalente. Por otro lado, se espera demostrar que los isotipos de tubulina encontrados en T. cruzi cambien en cantidad relativa y nivel de expresión cuando los epimastigotes sean estimulados con posibles inductores de la diferenciación. Además, se espera observar simultáneamente un aumento en la actividad de dos enzimas relacionadas con la reorganización de microtúbulos: PI-3K y PLD. En tal caso, y para comprobar su implicancia en el proceso, se espera que la inhibición de tales enzimas sea capaz de revertir el efecto producido por los estímulos. Como la PLC se expresa principalmente en las forma epimastigotes mas que en los tripomastigotes (forma infectiva), la señal de Ca2+ inducida por IP3 se relacionaría con la capacidad del parásito para responder a ciertos cambios de pH y osmolaridad que enfrenta el microorganismo en el tracto digestivo del insecto vector.

Auditoria contable en las pymes. Vinculación de la contabilidad de gestión y la contabilidad financiera en las pymes.

El presente proyecto es continuación del anterior que trataba de la elaboración de bases para la construcción de normas contables para PYMES. La temática si bien se refiere a PYMES, ciertos aspectos necesariamente son aplicables también a entes de mayor tamaño. Los temas a investigar son los siguientes: 1.- Auditoría contable para PYMES: Procedimientos adecuados para este tipo de entes, con un interrogante básico:¿deben existir?. 2.-Otras informaciones que la contabilidad puede brindar a los usuarios externos y también a los usuarios internos. En los últimos años se incrementó la separación entre la contabilidad llamada financiera y la contabilidad de gestión. Debe ser así?, no es posible pensar que la contabilidad de gestión puede brindar informaciones útiles también a los usuarios externos?. 3.-Actualmente existe una distorsión importante en los estados contables producto de la inflación y con especial problema en la inexistencia de índices confiables. Pero el problema del impacto de la inflación en las informaciones contables sigue existiendo. Nos proponemos investigar caminos alternativos sobre la base de la experiencia nacional e internacional.

PARTICIPACIÓN DEL SISTEMA SEROTONINÉRGICO CENTRAL EN LA REGULACIÓN DEL APETITO POR EL SODIO

Estudios previos del laboratorio han demostrado que la depleción de sodio inducida por diálisis peritoneal (DP) produce una rápida caída en la concentración de sodio del suero y del fluido cerebrospinal entre las 1-4hs después de la DP; sin embargo el apetito específico por el sodio (AS) aparece recién 20 hs después cuando se han recuperado los niveles normales de sodio extracelular quizás por medio de fuentes reservorias del cuerpo como hueso e higado. En nuestros trabajos además hemos identificado las distintas áreas y sistemas neuroquímicos involucrados tanto en la fase apetitiva (24hs después de la DP) como en la fase de saciedad del AS (luego del consumo de NaCl hipertónico inducido por DP). En estos estudios la depleción de sodio incrementó la actividad neuronal, evidenciada mediante la inmunoreactividad a Fos (ir-Fos), a lo largo de los órganos circunventriculares (OCVs) de la lamina terminalis (LT): órgano subfornical (SFO) y órgano vasculoso de la lamina terminalis, y diminuyó ir-Fos de las neuronas serotoninérgicas del núcleo del rafe dorsal (DRN), sugiriendo su participación en la génesis del AS. Por otro lado, durante la fase de saciedad la ir-Fos se incrementó dentro de áreas del tronco encefálico como el núcleo del tracto solitario, área postrema, núcleo parabraquial lateral (LPBN), neuronas serotoninérgicas del DRN y a lo largo de las células oxitocinérgicas hipotalámicas indicando su participación en la inhibición del AS. A pesar del conocimiento acumulado acerca de la regulación central del AS, hasta el momento, no se conocen cuales son los mecanismos, áreas y sistemas neuroquímicos involucrados en la disociación temporal existente entre la depleción de sodio y la aparición del AS. Numerosas líneas de evidencia sugieren que el AS es estimulado por la misma señal molecular que la sed hipovolemica, principalmente angiontensina II (ANGII), pero no se manifiesta porque es bloqueada por una señal inhibitoria dominante. Se sugiere que los efectos estimulatorios de ANGII sobre la ingesta de agua y sodio involucran la interacción con el circuito serotoninérgico (5HT) inhibitorio central. El circuito 5HT central que subyace a esta interacción incluye principalmente conexiones bidireccionales entre los OCVs de la LT donde se estimula la sed y AS y los somas 5HT del DRN y los terminales 5HT presentes en el LPBN donde se inhibiría el AS. Consistente con estos datos, la lesión del DRN y la inyección de antagonistas serotoninérgicos en el LPBN provocan un aumento significativo en el consumo de sodio inducido por distintos modelos experimentales.Nuestros resultados recientes indican que ya a las 2hs luego de la DP se incrementa la actividad de renina plasmática y a nivel central se observa una actividad tónica de las neuronas serotoninérgicas del DRN y la activación simultánea de los OCVs de la LT y de los núcleos de tronco encefálicos, estructuras previamente involucradas tanto en la fase apetitiva como de saciedad respectivamente. Con lo cual, es posible hipotetizar que el sistema 5HT a nivel del tronco (DRN, LPBN) estaría impidiendo el consumo de sodio estimulado por ANGII a las 2hs de la depleción de sodio corporal cuando se produce la caída en la natremia y en la volemia pero el AS no se manifiesta. De acuerdo con esto nos proponemos evaluar el efecto de una lesión transitoria y reversible del DRN, y el antagonismo del sistema 5HT a nivel del LPBN a las 2hs de realizada la DP sobre la ingesta de sodio. Además, se utilizará la técnica de registro electrofisiológico in vivo que nos permitirá estudiar la interconexión sináptica funcional entre el DRN y el SFO ante la infusión icv de ANGII. Esperamos observar un incremento en el consumo de sodio 2hs después de la DP, producido por el bloqueo transitorio o antagonismo del sistema serotoninérgico en el DRN o LPBN respectivamente. Además creemos posible que disminuya la actividad eléctrica de las neuronas 5HT del DRN que son moduladas por el SFO ante la inyección icv de AII.

Role of microRNAs 221/222 on Statin Induced Nitric Oxide Release in Human Endothelial Cells

Background: Nitric oxide (NO) has been largely associated with cardiovascular protection through improvement of endothelial function. Recently, new evidence about modulation of NO release by microRNAs (miRs) has been reported, which could be involved with statin-dependent pleiotropic effects, including anti-inflammatory properties related to vascular endothelium function. Objective: To evaluate the effects of cholesterol-lowering drugs including the inhibitors of cholesterol synthesis, atorvastatin and simvastatin, and the inhibitor of cholesterol absorption ezetimibe on NO release, NOS3 mRNA expression and miRs potentially involved in NO bioavailability. Methods: Human umbilical vein endothelial cells (HUVEC) were exposed to atorvastatin, simvastatin or ezetimibe (0 to 5.0 μM). Cells were submitted to total RNA extraction and relative quantification of NOS3 mRNA and miRs -221, -222 and -1303 by qPCR. NO release was measured in supernatants by ozone-chemiluminescence. Results: Both statins increased NO levels and NOS3 mRNA expression but no influence was observed for ezetimibe treatment. Atorvastatin, simvastatin and ezetimibe down-regulated the expression of miR-221, whereas miR-222 was reduced only after the atorvastatin treatment. The magnitude of the reduction of miR-221 and miR-222 after treatment with statins correlated with the increment in NOS3 mRNA levels. No influence was observed on the miR-1303 expression after treatments. Conclusion: NO release in endothelial cells is increased by statins but not by the inhibitor of cholesterol absorption, ezetimibe. Our results provide new evidence about the participation of regulatory miRs 221/222 on NO release induction mediated by statins. Although ezetimibe did not modulate NO levels, the down-regulation of miR-221 could involve potential effects on endothelial function.

Efficacy of Patient Selection for Diagnostic Coronary Angiography in Suspected Coronary Artery Disease

AbstractBackground:Guidelines recommend that in suspected stable coronary artery disease (CAD), a clinical (non-invasive) evaluation should be performed before coronary angiography.Objective:We assessed the efficacy of patient selection for coronary angiography in suspected stable CAD.Methods:We prospectively selected consecutive patients without known CAD, referred to a high-volume tertiary center. Demographic characteristics, risk factors, symptoms and non-invasive test results were correlated to the presence of obstructive CAD. We estimated the CAD probability based on available clinical data and the incremental diagnostic value of previous non-invasive tests.Results:A total of 830 patients were included; median age was 61 years, 49.3% were males, 81% had hypertension and 35.5% were diabetics. Non-invasive tests were performed in 64.8% of the patients. At coronary angiography, 23.8% of the patients had obstructive CAD. The independent predictors for obstructive CAD were: male gender (odds ratio [OR], 3.95; confidence interval [CI] 95%, 2.70 - 5.77), age (OR for 5 years increment, 1.15; CI 95%, 1.06 - 1.26), diabetes (OR, 2.01; CI 95%, 1.40 - 2.90), dyslipidemia (OR, 2.02; CI 95%, 1.32 - 3.07), typical angina (OR, 2.92; CI 95%, 1.77 - 4.83) and previous non-invasive test (OR 1.54; CI 95% 1.05 - 2.27).Conclusions:In this study, less than a quarter of the patients referred for coronary angiography with suspected CAD had the diagnosis confirmed. A better clinical and non-invasive assessment is necessary, to improve the efficacy of patient selection for coronary angiography.