Changes in pH at the dentin surface in roots obturated with calcium hydroxide pastes

The purpose of this study was to determine the pH, after defined periods of time, in cavities prepared in the facial surface of the cervical, middle, and apical regions of roots obturated with calcium hydroxide pastes. Root canal instrumentation was performed on 40 recently extracted, single-rooted human teeth. Cavities 1.5 mm in diameter and 0.75 mm in depth were prepared in the cervical, middle, and apical regions of the facial surface of each root. Teeth were randomly divided into four groups. One group was left unobturated and served as a control. The three remaining groups were obturated with either aqueous calcium hydroxide, calcium hydroxide mixed with camphorated monochlorophenol, or Pulpdent pastes. Access cavities and apical foramina were closed with Cavit. Each tooth was stored individually in a vial containing unbuffered isotonic saline. pH at the surface was measured in the cervical, middle, and apical cavities at 0 and 3, 7, 14, 21, 28, 45, 60, 90, and 120 days. Results indicate that hydroxyl ions derived from calcium hydroxide pastes diffused through root dentin at all regions over the experimental period of 120 days. The pattern of pH change at the tooth surface was similar in all regions of the root, regardless of the type of calcium hydroxide paste used. This was a rapid rise in pH from a control value of pH 7.6, to greater than pH 9.5 by 3 days, followed by a small decline to pH 9.0 over the next 18 days, before finally rising and remaining at, or above pH 10.0 for the remainder of the experimental period. Pulpdent paste in the apical region was the only exception in this pattern, producing a pH rise nearly one full unit below the other pastes, pH 9.3. These results indicate that, for all pastes tested, a high pH is maintained at the root surface for at least 120 days. Copyright © 1996 by The American Association of Endodontists.

Systematic vegetative anatomy and ensiform leaf development in Xyris (Xyridaceae)

Ensiform leaf development in monocotyledons follows a broadly similar sequence in a wide range of relatively unrelated taxa, indicating a plastic developmental pattern, possibly associated with stressed environmental conditions, since Xyris species tend to grow in relatively damp but nutrient-poor environments. The bifacial leaf sheath surrounds the apex and the subadjacent primordium. A conical unifacial leaf tip 'Vorlauferspitze' is established at an early stage, followed by extension growth in the region behind it, generating a unifacial ensiform blade. Root and rhizome structure are also described in a systematic context, particularly in comparison with related taxa in Xyridaceae and other commelinoid monocotyledons, although information on these structure is relatively sparse.

Influence of temperature and concentration on thermophysical properties of yellow mombin (Spondias mombin, L.)

Thermal conductivity, thermal diffusivity, and density of yellow mombin juice were determined at 8.8-49.4 °Brix and at temperature from 0.4 to 77.1 °C. Apparent viscosity was also measured between 7.8 and 30 °Brix and at temperature from 0 to 60 °C. Yellow mombin juice was produced from fruits of two different batches and the concentration process was performed using a roto evaporator or a rising film evaporator, single effect, with recirculation, under vacuum, to obtain concentrated juice. In order to obtain different concentrations, concentrated juice was diluted with distilled water. Multiple regression analysis was performed to fit thermal conductivity, thermal diffusivity and density experimental data obtaining a good fit. Arrhenius and power law relationships were proposed to fit apparent viscosity as a function of temperature and juice concentration at typical shear rates found during processing. The rheological parameters together with experimental values of pressure loss in tube flow were used to calculate friction factors, which were compared to those resulting from theoretical equation.

Uso da fitossociologia na avaliação da efetividade da restauração florestal em uma várzea degradada do rio Mogi Cuaçu, SP

This study objective was to evaluate the effective revegetation in a Mogi Guaçu River degraded floodplain area, located at Luiz Antonio municipality (21° 31' S e 47° 55' W), São Paulo State, Brazil. Two native riparian forest remnants (RIP1 and RIP2) and three 10-year-old reforested areas, planted of native species (R1, R2 and R3), were analyzed by using phytosociological describers of the arboreal stratum (trees with DBH ≥ 5 cm) as indicators. The arboreal stratum inventory was accomplished by 180 plots (10 × 10 m each), 60 representing every native forest and 20 for every reforested area. A total of 60 arboreal species was recorded, only six species (Cecropia hololeuca, Crotón urucurana, Genipa americana, Inga striata, Nectandra megapotamica e Peltophorum dubium) occurring in all the five studied areas. Seventeen species were common to both native forests, and nine species were recorded in all the reforested areas. Sebastlania commersonlana and Guarea macrophyllawere recorded in the native forests (RlP1 and RIP2), and Cecropia hololeuca, Croton urucurana and Inga striata occurring in all the reforested areas, were the species that best characterize the physiognomy of local diversity and were the most important among the studied species. The results showed that the rehabilitation of the areas made by the reforestation created conditions to implant forests with similar structures of the adjacent natural remainders. The reforestation with native species performed in the degraded floodplain of Mogi Guaçu River, initially with the predomination of invasive grasses, has been effective at the first stage of the ecological restoration process. The reforestation is making possible the natural regeneration of species from the adjacent remnants, what indicates that the similarity between planted forests and the native ones are rising through the time. The phytosociology, accomplished ten years after the planting date, is adequate to evaluate the effectiveness of the reforestation during the restoration process of degradated areas in the Mogi Guaçu floodplain.

Applying a genetic neuro-model reference adaptive controller in drilling optimization

Motivated by rising drilling operation costs, the oil industry has shown a trend toward real-time measurements and control. In this scenario, drilling control becomes a challenging problem for the industry, especially due to the difficulty associated with parameters modeling. One of the drillbit performance evaluators, the Rate Of Penetration (ROP), has been used as a drilling control parameter. However, relationships between operational variables affecting the ROP are complex and not easily modeled. This work presents a neuro-genetic adaptive controller to treat this problem. It is based on an auto-regressive with extra input signals, or ARX model and on a Genetic Algorithm (GA) to control the ROP. © [2006] IEEE.

A genetic neuro-model reference adaptive controller for petroleum wells drilling operations

Motivated by rising drilling operation costs, the oil industry has shown a trend towards real-time measurements and control. In this scenario, drilling control becomes a challenging problem for the industry, especially due to the difficulty associated to parameters modeling. One of the drill-bit performance evaluators, the Rate of Penetration (ROP), has been used in the literature as a drilling control parameter. However, the relationships between the operational variables affecting the ROP are complex and not easily modeled. This work presents a neuro-genetic adaptive controller to treat this problem. It is based on the Auto-Regressive with Extra Input Signals model, or ARX model, to accomplish the system identification and on a Genetic Algorithm (GA) to provide a robust control for the ROP. Results of simulations run over a real offshore oil field data, consisted of seven wells drilled with equal diameter bits, are provided. © 2006 IEEE.

Modelagem numérica da superfície na geração da planialtimetra segundo dados de quatro equipamentos topogríficos

The aim of this present work was to compare planialtimetric charts obtained from different risings using two different theodolite types, a total station, and a precision level, used as control. Using a total station, an area was marked with clear variations of relief, following a grid, with a distance of 20 meters among stakes. After that, the stakes were read by the total station and two theodolites of different precisions. The geometric leveling was done by a precision level. The data were input in the DataGeosis software and the numerical modelling of the land was made with mesh of maximum rigidity, generating planialtimetric representation for each rising. It was verified, through comparison of the four representations that little variations occur in relation to the control. The closest representation of the control was the planialtimetry based on the data from the total station, in which the representations obtained from the theodolites were identical among themselves. It was concluded that in the process of obtaining detailed planialtimetry of small areas, submitted to the grid, it was not necessary to use composed geometric leveling, reducing work to the exclusive use of a total station or conventional theodolite.

Preliminary Overview of the Economies of Latin America and the Caribbean 2006

Includes bibliography

Preliminary Overview of the Economies of Latin America and the Caribbean 2011

Incluye Bibliografía

Economic Survey of Latin America and the Caribbean 2010-2011: Internacional integration and macroeconomic policy challenges amid global economic turmoil

Includes bibliography

Economic survey of Latin America and the Caribbean 2012: policies for an adverse international economy

Includes bibliography

A comparative study of the damping oscillation function of TCSC and UPFC

The main objective of this work is to analyze the ability of FACTS devices like TCSC and UPFC to damp low frequency oscillations and a POD controller is also included. A comparative study of damping effect of those devices IS carried out. The Power Sensitivity Model (PSM) is used to the representation of the electric power system. Sensibility analysis using the residue method shows the best place for the installation of FACTS and the procedure to determine POD parameters. ©2008 IEEE.

Social Panorama of Latin America 2000-2001

Includes bibliography

Social Panorama of Latin America 2001-2002

Includes bibliography

Social Panorama of Latin America 2007

Includes bibliography