REALISTIC IVUS IMAGE GENERATION IN DIFFERENT INTRALUMINAL PRESSURES

Intravascular ultrasound (IVUS) phantoms are important to calibrate and evaluate many IVUS imaging processing tasks. However, phantom generation is never the primary focus of related works; hence, it cannot be well covered, and is usually based on more than one platform, which may not be accessible to investigators. Therefore, we present a framework for creating representative IVUS phantoms, for different intraluminal pressures, based on the finite element method and Field II. First, a coronary cross-section model is selected. Second, the coronary regions are identified to apply the properties. Third, the corresponding mesh is generated. Fourth, the intraluminal force is applied and the deformation computed. Finally, the speckle noise is incorporated. The framework was tested taking into account IVUS contrast, noise and strains. The outcomes are in line with related studies and expected values. Moreover, the framework toolbox is freely accessible and fully implemented in a single platform. (E-mail: fernando.okara@gmail.com) (c) 2012 World Federation for Ultrasound in Medicine & Biology.

Automatic lumen segmentation in IVOCT images using binary morphological reconstruction

Abstract Background Atherosclerosis causes millions of deaths, annually yielding billions in expenses round the world. Intravascular Optical Coherence Tomography (IVOCT) is a medical imaging modality, which displays high resolution images of coronary cross-section. Nonetheless, quantitative information can only be obtained with segmentation; consequently, more adequate diagnostics, therapies and interventions can be provided. Since it is a relatively new modality, many different segmentation methods, available in the literature for other modalities, could be successfully applied to IVOCT images, improving accuracies and uses. Method An automatic lumen segmentation approach, based on Wavelet Transform and Mathematical Morphology, is presented. The methodology is divided into three main parts. First, the preprocessing stage attenuates and enhances undesirable and important information, respectively. Second, in the feature extraction block, wavelet is associated with an adapted version of Otsu threshold; hence, tissue information is discriminated and binarized. Finally, binary morphological reconstruction improves the binary information and constructs the binary lumen object. Results The evaluation was carried out by segmenting 290 challenging images from human and pig coronaries, and rabbit iliac arteries; the outcomes were compared with the gold standards made by experts. The resultant accuracy was obtained: True Positive (%) = 99.29 ± 2.96, False Positive (%) = 3.69 ± 2.88, False Negative (%) = 0.71 ± 2.96, Max False Positive Distance (mm) = 0.1 ± 0.07, Max False Negative Distance (mm) = 0.06 ± 0.1. Conclusions In conclusion, by segmenting a number of IVOCT images with various features, the proposed technique showed to be robust and more accurate than published studies; in addition, the method is completely automatic, providing a new tool for IVOCT segmentation.

Application of Polysaccharide Hydrogels in Adsorption and Controlled-Extended Release of Fertilizers Processes

This article studied the applicability of poly(acrylamide) and methylcellulose (PAAm-MC) hydrogels as potential delivery vehicle for the controlled-extended release of ammonium sulfate (NH(4))(2)SO(4) and potassium phosphate (KH(2)PO(4)) fertilizers. PAAm-MC hydrogels with different acrylamide (AAm) and MC concentrations were prepared by a free radical polymerization method. The adsorption and desorption kinetics of fertilizers were determined using conductivity measurements based on previously built analytical curve. The addition of MC in the PAAm chains increased the quantities of (NH(4))(2)SO(4) and KH(2)PO(4) loaded and extended the time and quantities of fertilizers released. Coherently, both loading and releasing processes were strongly influenced by hydrophilic properties of hydrogels (AAm/MC mass proportion). The best sorption (124.0 mg KH(2)PO(4)/g hydrogel and 58.0 mg (NH(4))(2)SO(4)/g hydrogel) and desorption (54.9 mg KH(2)PO(4)/g hydrogel and 49.5 mg (NH(4))(2)SO(4)/g hydrogel) properties were observed for 6.0% AAm-1.0% MC hydrogels (AAm/MC mass proportion equal 6), indicating that these hydrogels are potentially viable to be used in controlled-extended release of fertilizers systems. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: 2291-2298, 2012

Introducing education for sustainable development in the undergraduate laboratory: quantitative analysis of bioethanol fuel and its blends with gasoline by using solvatochromic dyes

The concept of Education for Sustainable Development, ESD, has been introduced in a period where chemistry education is undergoing a major change, both in emphasis and methods of teaching. Studying an everyday problem, with an important socio-economic impact in the laboratory is a part of this approach. Presently, the students in many countries go to school in vehicles that run, at least partially, on biofuels; it is high time to let them test these fuels. The use of renewable fuels is not new: since 1931 the gasoline sold in Brazil contains 20 to 25 vol-% of bioethanol; this composition is being continually monitored. With ESD in mind, we have employed a constructivist approach in an undergraduate course, where UV-vis spectroscopy has been employed for the determination of the composition of two fuel blends, namely, bioethanol/water, and bioethanol/gasoline. The activities started by giving a three-part quiz. The first and second ones introduced the students to historical and practical aspects of the theme (biofuels). In the third part, we asked them to develop a UV-vis experiment for the determination of the composition of fuel blends. They have tested two approaches: (i) use of a solvatochromic dye, followed by determination of fuel composition from plots of the empirical fuel polarity versus its composition; (ii) use of an ethanol-soluble dye, followed by determination of the blend composition from a Beer's law plot; the former proved to be much more convenient. Their evaluation of the experiment was highly positive, because of the relevance of the problem; the (constructivist) approach employed, and the bright colors that the solvatochromic dye acquire in these fuel blends. Thus ESD can be fruitfully employed in order to motivate the students; make the laboratory "fun", and teach them theory (solvation). The experiments reported here can also be given to undergraduate students whose major is not chemistry (engineering, pharmacy, biology, etc.). They are low-cost and safe to be introduced at high-school level.

Development of site-specific sediment quality guidelines for North and South Atlantic littoral zones: Comparison against national and international sediment quality benchmarks

We aimed to develop site-specific sediment quality guidelines (SQGs) for two estuarine and port zones in Southeastern Brazil (Santos Estuarine System and Paranagua Estuarine System) and three in Southern Spain (Ria of Huelva, Bay of Cadiz, and Bay of Algeciras), and compare these values against national and traditionally used international benchmark values. Site-specific SQGs were derived based on sediment physical-chemical, toxicological, and benthic community data integrated through multivariate analysis. This technique allowed the identification of chemicals of concern and the establishment of effects range correlatively to individual concentrations of contaminants for each site of study. The results revealed that sediments from Santos channel, as well as inner portions of the SES, are considered highly polluted (exceeding SQGs-high) by metals, PAHs and PCBs. High pollution by PAHs and some metals was found in Sao Vicente channel. In PES, sediments from inner portions (proximities of the Ponta do Mix port`s terminal and the Port of Paranagua) are highly polluted by metals and PAHs, including one zone inside the limits of an environmental protection area. In Gulf of Cadiz, SQGs exceedences were found in Ria of Huelva (all analysed metals and PAHs), in the surroundings of the Port of CAdiz (Bay of CAdiz) (metals), and in Bay of Algeciras (Ni and PAHs). The site-specific SQGs derived in this study are more restricted than national SQGs applied in Brazil and Spain, as well as international guidelines. This finding confirms the importance of the development of site-specific SQGs to support the characterisation of sediments and dredged material. The use of the same methodology to derive SQGs in Brazilian and Spanish port zones confirmed the applicability of this technique with an international scope and provided a harmonised methodology for site-specific SQGs derivation. (C) 2009 Elsevier B.V. All rights reserved.

Reconnection current sheet structure in a turbulent medium

In the presence of turbulence, magnetic field lines lose their dynamical identity and particles entrained on field lines diffuse through space at a rate determined by the amplitude of the turbulence. In previous work (Lazarian and Vishniac, 1999; Kowal et al., 2009; Eyink et al., 2011) we showed that this leads to reconnection speeds which are independent of resistivity. In particular, in Kowal et al. (2009) we showed that numerical simulations were consistent with the predictions of this model. Here we examine the structure of the current sheet in simulations of turbulent reconnection. Laminar flows consistent with the Sweet-Parker reconnection model produce very thin and well ordered currents sheets. On the other hand, the simulations of Kowal et al. (2009) show a strongly disordered state even for relatively low levels of turbulence. Comparing data cubes with and without reconnection, we find that large scale field reversals are the cumulative effect of many individual eddies, each of which has magnetic properties which are not very different from turbulent eddies in a homogeneous background. This implies that the properties of stationary and homogeneous MHD turbulence are a reasonable guide to understanding turbulence during large scale magnetic reconnection events. In addition, dissipation and high energy particle acceleration during reconnection events take place over a macroscopic volume, rather than being confined to a narrow zone whose properties depend on microscopic transport coefficients.

Reconnection studies under different types of turbulence driving

We study a model of fast magnetic reconnection in the presence of weak turbulence proposed by Lazarian and Vishniac (1999) using three-dimensional direct numerical simulations. The model has been already successfully tested in Kowal et al. (2009) confirming the dependencies of the reconnection speed V-rec on the turbulence injection power P-inj and the injection scale l(inj) expressed by a constraint V-rec similar to P(inj)(1/2)l(inj)(3/4)and no observed dependency on Ohmic resistivity. In Kowal et al. (2009), in order to drive turbulence, we injected velocity fluctuations in Fourier space with frequencies concentrated around k(inj) = 1/l(inj), as described in Alvelius (1999). In this paper, we extend our previous studies by comparing fast magnetic reconnection under different mechanisms of turbulence injection by introducing a new way of turbulence driving. The new method injects velocity or magnetic eddies with a specified amplitude and scale in random locations directly in real space. We provide exact relations between the eddy parameters and turbulent power and injection scale. We performed simulations with new forcing in order to study turbulent power and injection scale dependencies. The results show no discrepancy between models with two different methods of turbulence driving exposing the same scalings in both cases. This is in agreement with the Lazarian and Vishniac (1999) predictions. In addition, we performed a series of models with varying viscosity nu. Although Lazarian and Vishniac (1999) do not provide any prediction for this dependence, we report a weak relation between the reconnection speed with viscosity, V-rec similar to nu(-1/4).

Engineering geological data in support of municipal land use planning-a case study in Analandia, southeast Brazil

This paper presents a method for transforming the information of an engineering geological map into useful information for non-specialists involved in land-use planning. The method consists of classifying the engineering geological units in terms of land use capability and identifying the legal and the geologic restrictions that apply in the study area. Both informations are then superimposed over the land use and a conflict areas map is created. The analysis of these data leads to the identification of existing and forthcoming land use conflicts and enables the proposal of planning measures on a regional and local scale. The map for the regional planning was compiled at a 1:50,000 scale and encompasses the whole municipal land area where uses are mainly rural. The map for the local planning was compiled at a 1:10,000 scale and encompasses the urban area. Most of the classification and operations on maps used spatial analyst tools available in the Geographical Information System. The regional studies showed that the greater part of Analandia's territory presents appropriate land uses. The local-scale studies indicate that the majority of the densely occupied urban areas are in suitable land. Although the situation is in general positive, municipal policies should address the identified and expected land use conflicts, so that it can be further improved.

Sciatic nerve regeneration in rats by a nerve conduit engineering with a membrane derived from natural latex

PURPOSE: To evaluate the capacity of natural latex membrane to accelerate and improve the regeneration quality of the of rat sciatic nerves. METHODS: Forty male adult Wistar rats were used, anesthetized and operated to cut the sciatic nerve and receive an autograft or a conduit made with a membrane derived from natural latex (Hevea brasiliensis). Four or eight weeks after surgery, to investigate motor nerve recovery, we analyzed the neurological function by walking pattern (footprints analysis and computerized treadmill), electrophysiological evaluation and histological analysis of regenerated nerve (autologous nerve graft or tissue cables between the nerve stumps), and anterior tibial and gastrocnemius muscles. RESULTS: All functional and morphological analysis showed that the rats transplanted with latex conduit had a better neurological recovery than those operated with autologous nerve: quality of footprints, performance on treadmill (p<0.01), electrophysiological response (p<0.05), and quality of histological aspects on neural regeneration. CONCLUSION: The data reported showed behavioral and functional recovery in rats implanted with latex conduit for sciatic nerve repair, supporting a complete morphological and physiological regeneration of the nerve.

Laboratory and in situ studies on a compacted clayey silt fill

This paper presents laboratory and in situ studies carried out on a 200 000 m(3) large clayey silt compacted embankment. Laboratory studies carried out on undeformed block samples included index tests, strength tests and water retention curves using the filter paper technique. Grain size analyses with and without a deflocculating agent clearly showed the existence of grain clusters, which appear to be naturally formed. Field instrumentation installed at depths from 0.25 m to 1.0 m included tensiometers, equitensiometers, time domain reflectometry and geothermometers. Pluviometer data from a nearby weather station are also used to analyse the field data. The ranges of water content and suction values were measured, both of which correlated well with the pluviometer data. The water retention curves including laboratory and field data showed a bimodal shape, consistent with the presence of microand macropores shown in the grain size analysis.

Flow Visualization with Quantified Spatial and Temporal Errors Using Edge Maps

Robust analysis of vector fields has been established as an important tool for deriving insights from the complex systems these fields model. Traditional analysis and visualization techniques rely primarily on computing streamlines through numerical integration. The inherent numerical errors of such approaches are usually ignored, leading to inconsistencies that cause unreliable visualizations and can ultimately prevent in-depth analysis. We propose a new representation for vector fields on surfaces that replaces numerical integration through triangles with maps from the triangle boundaries to themselves. This representation, called edge maps, permits a concise description of flow behaviors and is equivalent to computing all possible streamlines at a user defined error threshold. Independent of this error streamlines computed using edge maps are guaranteed to be consistent up to floating point precision, enabling the stable extraction of features such as the topological skeleton. Furthermore, our representation explicitly stores spatial and temporal errors which we use to produce more informative visualizations. This work describes the construction of edge maps, the error quantification, and a refinement procedure to adhere to a user defined error bound. Finally, we introduce new visualizations using the additional information provided by edge maps to indicate the uncertainty involved in computing streamlines and topological structures.

PBL and B-Learning for Civil Engineering Students in a Transportation Course

The results of a pedagogical strategy implemented at the University of Sao Paulo at Sao Carlos are presented and discussed. The initiative was conducted in a transportation course offered to Civil Engineering students. The approach is a combination of problem-based learning and project-based learning (PBL) and blended-learning (B-learning). Starting in 2006, a different problem was introduced every year. From 2009 on, however, the problem-based learning concept was expanded to project-based learning. The performance of the students was analyzed using the following elements: (1) grades in course activities; (2) answers from a questionnaire designed for course evaluation; and (3) cognitive maps made to assess the effects of PBL through the comparison of the responses provided by the students involved and those not involved in the experiment. The results showed positive aspects of the method, such as a strong involvement of several students with the subject. A gradual increase in the average scores obtained by the students in the project activities (from 6.77 in 2006 to 8.24 in 2009) was concomitant with a better evaluation of these activities and of the course as a whole (90 and 97% of options "Good" or "Very good" in 2009, respectively). A growing interest in the field of transportation engineering as an alternative for further studies was also noticed. DOI: 10.1061/(ASCE)EI.1943-5541.0000115. (C) 2012 American Society of Civil Engineers.

Pore size regulates cell and tissue interactions with PLGA-CaP scaffolds used for bone engineering

A common subject in bone tissue engineering is the need for porous scaffolds to support cell and tissue interactions aiming at repairing bone tissue. As poly(lactide-co-glycolide)calcium phosphate (PLGACaP) scaffolds can be manufactured with different pore sizes, the aim of this study was to evaluate the effect of pore diameter on osteoblastic cell responses and bone tissue formation. Scaffolds were prepared with 85% porosity, with pore diameters in the ranges 470590, 590850 and 8501200 mu m. Rat bone marrow stem cells differentiated into osteoblasts were cultured on the scaffolds for up to 10 days to evaluate cell growth, alkaline phosphatase (ALP) activity and the gene expression of the osteoblast markers RUNX2, OSX, COL, MSX2, ALP, OC and BSP by real-time PCR. Scaffolds were implanted in critical size rat calvarial defects for 2, 4, and 8 weeks for histomorphometric analysis. Cell growth and ALP activity were not affected by the pore size; however, there was an increase in the gene expression of osteoblastic markers with the increase in the pore sizes. At 2 weeks all scaffolds displayed a similar amount of bone and blood vessels formation. At 4 and 8 weeks much more bone formation and an increased number of blood vessels were observed in scaffolds with pores of 470590 mu m. These results show that PLGACaP is a promising biomaterial for bone engineering. However, ideally, combinations of larger (similar to 1000 mu m) and smaller (similar to 500 mu m) pores in a single scaffold would optimize cellular and tissue responses during bone healing. Copyright (C) 2011 John Wiley & Sons, Ltd.

Origin of Anomalous Activities for Electrocatalysts in Alkaline Electrolytes

Pt extended surfaces and nanoparticle electrodes are used to understand the origin of anomalous activities for electrocatalytic reactions in alkaline electrolytes as a function of cycling/time. Scanning tunneling microscopy (STM) of the surfaces before and after cycling in alkaline electrolytes was used to understand the morphology of the impurities and their impact on the catalytic sites. The nature of the contaminant species is identified as 3d-transition metal cations, and the formation of hydr(oxy)oxides of these elements is established as the main reason for the observed behavior. We find that, while for the oxygen reduction reaction (ORR) and the hydrogen oxidation reaction (HOR) the blocking of the sites by the undesired 3d-transition metal hydr(oxy)oxide species leads to deactivation of the reaction activities, the CO oxidation reaction and the hydrogen evolution reaction (HER) can have beneficial effects from the same impurities, the latter being dependent on the exact nature of the adsorbing species. These results show the significance of impurities present in real electrolytes and their impact on electrocatalysis.