Estimação em modelos de tempo de falha acelerado para dados de sobrevivência correlacionados

We presented in this work two methods of estimation for accelerated failure time models with random e_ects to process grouped survival data. The _rst method, which is implemented in software SAS, by NLMIXED procedure, uses an adapted Gauss-Hermite quadrature to determine marginalized likelihood. The second method, implemented in the free software R, is based on the method of penalized likelihood to estimate the parameters of the model. In the _rst case we describe the main theoretical aspects and, in the second, we briey presented the approach adopted with a simulation study to investigate the performance of the method. We realized implement the models using actual data on the time of operation of oil wells from the Potiguar Basin (RN / CE).

Análise de resíduos em modelos de tempo de falha acelerado com efeito aleatório

We present residual analysis techniques to assess the fit of correlated survival data by Accelerated Failure Time Models (AFTM) with random effects. We propose an imputation procedure for censored observations and consider three types of residuals to evaluate different model characteristics. We illustrate the proposal with the analysis of AFTM with random effects to a real data set involving times between failures of oil well equipment

Indicadores de cálcio e de voltagem codificados geneticamente na detecção de potenciais de ação e inputs sinápticos em cultura de neurônios hipocampais

Recently, genetically encoded optical indicators have emerged as noninvasive tools of high spatial and temporal resolution utilized to monitor the activity of individual neurons and specific neuronal populations. The increasing number of new optogenetic indicators, together with the absence of comparisons under identical conditions, has generated difficulty in choosing the most appropriate protein, depending on the experimental design. Therefore, the purpose of our study was to compare three recently developed reporter proteins: the calcium indicators GCaMP3 and R-GECO1, and the voltage indicator VSFP butterfly1.2. These probes were expressed in hippocampal neurons in culture, which were subjected to patchclamp recordings and optical imaging. The three groups (each one expressing a protein) exhibited similar values of membrane potential (in mV, GCaMP3: -56 ±8.0, R-GECO1: -57 ±2.5; VSFP: -60 ±3.9, p = 0.86); however, the group of neurons expressing VSFP showed a lower average of input resistance than the other groups (in Mohms, GCaMP3: 161 ±18.3; GECO1-R: 128 ±15.3; VSFP: 94 ±14.0, p = 0.02). Each neuron was submitted to current injections at different frequencies (10 Hz, 5 Hz, 3 Hz, 1.5 Hz, and 0.7 Hz) and their fluorescence responses were recorded in time. In our study, only 26.7% (4/15) of the neurons expressing VSFP showed detectable fluorescence signal in response to action potentials (APs). The average signal-to-noise ratio (SNR) obtained in response to five spikes (at 10 Hz) was small (1.3 ± 0.21), however the rapid kinetics of the VSFP allowed discrimination of APs as individual peaks, with detection of 53% of the evoked APs. Frequencies below 5 Hz and subthreshold signals were undetectable due to high noise. On the other hand, calcium indicators showed the greatest change in fluorescence following the same protocol (five APs at 10 Hz). Among the GCaMP3 expressing neurons, 80% (8/10) exhibited signal, with an average SNR value of 21 ±6.69 (soma), while for the R-GECO1 neurons, 50% (2/4) of the neurons had signal, with a mean SNR value of 52 ±19.7 (soma). For protocols at 10 Hz, 54% of the evoked APs were detected with GCaMP3 and 85% with R-GECO1. APs were detectable in all the analyzed frequencies and fluorescence signals were detected from subthreshold depolarizations as well. Because GCaMP3 is the most likely to yield fluorescence signal and with high SNR, some experiments were performed only with this probe. We demonstrate that GCaMP3 is effective in detecting synaptic inputs (involving Ca2+ influx), with high spatial and temporal resolution. Differences were also observed between the SNR values resulting from evoked APs, compared to spontaneous APs. In recordings of groups of cells, GCaMP3 showed clear discrimination between activated and silent cells, and reveals itself as a potential tool in studies of neuronal synchronization. Thus, our results indicate that the presently available calcium indicators allow detailed studies on neuronal communication, ranging from individual dendritic spines to the investigation of events of synchrony in neuronal networks genetically defined. In contrast, studies employing VSFPs represent a promising technology for monitoring neural activity and, although still to be improved, they may become more appropriate than calcium indicators, since neurons work on a time scale faster than events of calcium may foresee

Detecção de bactérias periodontopatogênicas cultiváveis e não cultiváveis em placas ateromatosas

Periodontal infections consist of a group of inflammatory conditions caused by microorganisms that colonize the tooth surface through the formation of dental biofilm. Chronic infections such as periodontitis have been associated to the development and progression of atherosclerosis. AIM: Detect cultivatable and non-cultivatable periodontopathogenic bacteria in atheromatous plaques; search for factors associated to the presence of these bacteria in the atheromatous plaques and characterize the presence of cultivatable and non-cultivatable bacteria in these plaques. METHODOLOGY: A cross-sectional study was performed with a sample of 30 patients diagnosed with atherosclerosis in the carotid, coronary or femoral arteries and surgically treated with angioplasty and stent implant, bypass or endarterectomy. The plaques were collected during surgery and analyzed using the PCR molecular technique for the presence of the DNA of the cultivatable bacteria Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis and Treponema denticola and of the non-cultivatable Synergistes phylotypes. The patients were examined in the infirmary, after the surgery, where they also responded to a questionnaire aimed at determining factors associated to the presence of periodontopathogenic bacteria in the atheromatous plaques. RESULTS: All patients with tooth (66,7%) possessed disease periodontal, being 95% severe and 65% widespread. No periodontopathogenic bacteria were found in the atheromatous plaques. However, four samples (13.3%) were positive for the presence of bacteria. Of these, three participants were dentate, being two carriers of widespread severe chronic periodontite and one of located severe chronic periodontitis. None of them told the accomplishment of procedures associated to possible bacteremia episodes, as treatment endodontic, extraction the last six months or some procedure surgical dental. CONCLUSION: The periodontopathogenic bacteria studied were not found in the atheromatous plaques, making it impossible to establish the prevalence of these pathogens or the factors associated to their presence in plaques, the detection of positive samples for bacteria suggests that other periodontal and non-periodontal pathogens be studied in an attempt at discovering the association or not between periodontal disease and/or others infections and atherosclerosis, from the presence of these bacteria in atheromas

Estudo da detecção do DNA do papiloma vírus humano (HPV) e da expressão imuno-histoquímica de proteína do ciclo celular no carcinoma epidermóide oral

Oral squamous cell carcinoma (OSCC) is the most common malignancy in oral cavity and human papillomavirus (HPV) may have an important role in its development. The aim of this experiment was to investigate the HPV DNA and viral types in 90 cases of OSCC. Moreover, a comparative analysis between the cases of OSSC with and without HPV DNA was performed by using cell cycle markers p21 and pRb in order to detect a possible correlation of these proteins and HPV infection. DNA was extracted from paraffin embedded tissue and amplified by PCR (polymerase chain reaction) with primers PCO3+ e PCO4+ for a fragment of human β-globin gene. After this procedure, PCR for HPV DNA detection was realized using a pair of generic primers GP5+ e GP6+. Immunohistochemical study was performed by streptoavidin-biotin technique and antibodies against p21 and pRb proteins were employed. Eighty-eight cases were positive for human β-globin gene and HPV DNA was found in 26 (29.5%) of then. It could not be detected significant correlation between HPV and age, sex and anatomical sites of the lesion. The most prevalent viral type was HPV 18 (80.8%). Regarding the immunohistochemical analysis, it was detected significant association between HPV presence and pRb immunoexpression (p=0,044), nevertheless, the same was not observed in relation to p21 protein (p =0,416). It can be concluded that the low detection of HPV DNA in OSCC by the present experiment suggests a possible role of the virus in the development and progression in just a subset of this disease

Detecção de cor e forma por Callithrix jacchus em cativeiro

Callithrix jacchus studies involving differences between the sexes regarding the performance on tasks food still offers room for the investigation of some factors, among them there is the differences in color vision, which can directly influence the detection of visual clues on food items. This study aimed to analyze the performance of C. jacchus in tasks involving detection of food items. Some factors were analyzed such as the differences in performance between the sexes and behavioral categories present during the task. There were no differences in performance between the animals in carrying out the task, for all situations presented, examining the behavioral categories observed. The fact of the task to be very simple might have influenced the results, and it was not possible to observe differences in performance. Males and females showed the same performance in all analyzed situations. The sex differences were not found possibly due to the influence of external factors, such as the structure of the experimental apparatus. The animals are more efficient in carrying out the task during the morning, in comparison to the afternoon. The light may have been one of the factors that influenced these results. Due to the influence of other factors that probably contributed to these results, we believe that different results can be found in future work

Detecção de predadores por dicromatas e tricromatas humanos e a sua implicação na evolução da visão de cores em primatas

Among placental mammals, primates are the only ones to present trichromatic color vision. However, the distribution of trichromacy among primates is not homogeneous: Old World primates shows an uniform trichromacy (with all individuals being trichromats) and New World primates exhibit a color vision polymorphism (with dichromatic males and dichromatic or trichromatic females). Visual ecology studies have investigated which selective pressures may have been responsible for the evolution of trichromacy in primates, diverging from the dichromat standard found in other mammals. Cues associated with foraging and the socio-reproductive status were analyzed, indicating a trichromatic advantage for the rapid detection of visually conspicuous objects against a green background. However, dichromats are characterized by an efficient capture of cryptic and camouflaged stimuli. These advantages regarding phenotype may be responsible for the maintenance of the visual polymorphism in New World primates and for the high incidence of color blindness in humans (standing around 8% in Caucasian men). An important factor that has not yet been experimentally taken into account is the predation risk and its effect on the evolution of trichromacy in primates. To answer this question, we prepared and edited pictures of animals with different coats: oncillas (Leopardus spp.), puma (Puma concolor) and ferret (Galictis cuja). The specimens were taxidermized and the photographs were taken in three different vegetation scenarios (dense forest, cerrado and grassland). The images of the predators were manipulated so that they fit into two categories of stimulus size (small or large). After color calibration and photo editing, these were presented to 40 humans (20 dichromats and 20 trichromats) by a computer program, which presented a set of four photos at a time (one picture containing the taxidermized animal amid the background vegetation and three depicting only the background vegetation) and recorded the response latency and success rate of the subjects. The results show a trichromatic advantage in detecting potential predators. The predator detection was influenced by the background, the predator species, the dimension of the stimulus and the observer s visual phenotype. As humans have a high rate of dyschromatopsias, when compared to wild Catarrhini or human tribal populations, it is possible that the increased rate of dichromats is a result of reduced pressure for rapid predator detection. Since our species came to live in more cohesive groups and resistant to attack by predators, with the advent of agriculture and the formation of villages, it is possible that the lower risk of predation has reduced the selection in favor of trichromats

Análise fractográfica do modo de falha de compósitos carbono/epóxi

A utilização de compósitos poliméricos na fabricação de aeronaves vem sendo cada vez mais intensa. em função disso, a possibilidade de ocorrer falhas em serviço de um componente fabricado em compósito polimérico torna-se cada vez maior. A análise de falhas de materiais compósitos ainda é um tema pouco explorado, principalmente no Brasil, porém vem tornando-se cada vez mais importante em apoio à área de prevenção e investigação de acidentes aeronáuticos. Este trabalho teve como objetivo a caracterização de fraturas em laminados unidirecionais de fibra de carbono de módulo intermediário com sistema de resina epóxi modificada, tipo 8552, em resistência ao cisalhamento interlaminar nas condições ambiente e saturado de umidade em câmara higrotérmica. A análise fractográfica no plano de falha dos laminados foi realizada por microscopias óptica e eletrônica de varredura. A comparação dos resultados mostrou que o condicionamento higrotérmico afetou significativamente a região de interface da resina sem alterar a adesão interfacial fibra/resina. Os aspectos de fratura presentes na região de resina, como cristas de galo e escarpas, e do reforço foram detalhados, podendo-se assim estabelecer a direção de propagação da trinca e caracterizar o modo de falha, por ser do tipo misto (arrancamento e cisalhamento simultaneamente).

Exames parasitológicos, imunoistoquímicos e histopatológicos para detecção de Leishmania chagasi em tecidos esplênicos de cães com leishmaniose visceral

O propósito do presente trabalho foi o estudo da Leishmaniose Visceral Canina - LVC por meio de métodos parasitológicos e imunoistoquímicos para a detecção de formas amastigotas de Leishmania (L.) chagasi em baço, além de descrever a histopatologia das lesões esplênicas em 34 cães, com diferentes manifestações clínicas da LVC, eutanasiados pelo Centro de Controle de Zoonoses de Ilha Solteira, SP. Esses animais foram examinados clinicamente antes da eutánásia e de acordo com os sinais clínicos da LVC, foram classificados em três grupos: assintomáticos (8 cães), oligossintomáticos (17 cães) e sintomáticos (9 cães). Após a realização desses exames, dos 34 cães, 22 (64,7%) estavam positivos e 12 (35,3%) negativos. Desses cães positivos, 1/22 (4,5%) era assintomático, 12/22 (54,5%) eram oligossintomáticos e 9/22 (40,1%) sintomáticos. Pela histopatologia, os cães, especialmente os sintomáticos apresentavam o baço com inflamação crônica e espessamento na região capsular e trabecular, além de extensa alteração morfológica na polpa vermelha e branca pela presença de grande quantidade de macrófagos repletos de amastigotas, pela reação granulomatosa inflamatória e pelas áreas hemorrágicas. Os exames histopatológicos e a detecção microscópica direta da L. (L.) chagasi revelaram que o baço é um órgão útil para auxiliar no diagnóstico da LVC. A coloração imunoistoquímica foi a que detectou o maior número de tecidos esplênicos positivos com amastigotas, além de elucidar os casos suspeitos pelos exames parasitológicos, principalmente, nos animais assintomáticos ou oligossintomáticos.

Detecção de metamidofós em solos por métodos ecotoxicológico e cromatografia líquida acoplada à espectrometria de massas sequencial (LC-MS/MS)

Soil contamination by pesticides is an environmental problem that needs to be monitored and avoided. However, the lack of fast, accurate and low cost analytical methods for discovering residual pesticide in complex matrices, such as soil, is a problem still unresolved. This problem needs to be solved before we are able to assess the quality of environmental samples. The intensive use of pesticides has increased since the 60s, because the dependence of their use, causing biological imbalances and promoting resistance and recurrence of high populations of pests and pathogens (upwelling). This has contributed to the appearance of new pests that were previously under natural control. To develop analytical methods that are able to quantify residues pesticide in complex environment. It is still a challenge for many laboratories. The integration of two analytical methods one ecotoxicological and another chemical demonstrates the potential for environmental analysis of methamidophos. The aim of this study was to evaluate an ecotoxicological method as "screening" analytical methamidophos in the soil and perform analytical confirmation in the samples of the concentration of the analyte by chemical method LC-MS/MS In this work we tested two soils: a clayey and sandy, both in contact with the kinetic methamidophos model followed pseudo-second order. The clay soil showed higher absorption of methamidophos and followed the Freundlich model, while the sandy, the Langmuir model. The chemical method was validated LC-MS/MS satisfactory, showing all parameters of linearity, range, precision, accuracy, and sensitivity adequate. In chronic ecotoxicological tests with C. dubia, the NOEC was 4.93 and 3.24 for ng L-1 of methamidophos to elutriate assays of sandy and clay soils, respectively. The method for ecotoxicological levels was more sensitive than LC-MS/MS detection of methamidophos, loamy and sandy soils. However, decreasing the concentration of the standard for analytical methamidophos and adjusting for the validation conditions chemical acquires a limit of quantification (LOQ) in ng L-1, consistent with the provisions of ecotoxicological test. The methods described should be used as an analytical tool for methamidophos in soil, and the ecotoxicological analysis can be used as a "screening" and LC-MS/MS as confirmatory analysis of the analyte molecule, confirming the objectives of this work

Detecção e recuperação de falhas para a máquina de redução de grafos PEWS-AM

Web services are software units that allow access to one or more resources, supporting the deployment of business processes in the Web. They use well-defined interfaces, using web standard protocols, making possible the communication between entities implemented on different platforms. Due to these features, Web services can be integrated as services compositions to form more robust loose coupling applications. Web services are subject to failures, unwanted situations that may compromise the business process partially or completely. Failures can occur both in the design of compositions as in the execution of compositions. As a result, it is essential to create mechanisms to make the implementation of service compositions more robust and to treat failures. Specifically, we propose the support for fault recovery in service compositions described in PEWS language and executed on PEWS-AM, an graph reduction machine. To support recovery failure on PEWS-AM, we extend the PEWS language specification and adapted the rules of translation and reduction of graphs for this machine. These contributions were made both in the model of abstract machine as at the implementation level

Sistema de aquisição de dados para estudos de transiente de pressão e detecção de vazamentos em oleodutos

In February 2011, the National Agency of Petroleum, Natural Gas and Biofuels (ANP) has published a new Technical Rules for Handling Land Pipeline Petroleum and Natural Gas Derivatives (RTDT). Among other things, the RTDT made compulsory the use of monitoring systems and leak detection in all onshore pipelines in the country. This document provides a study on the method for detection of transient pressure. The study was conducted on a industrial duct 16" diameter and 9.8 km long. The pipeline is fully pressurized and carries a multiphase mixture of crude oil, water and natural gas. For the study, was built an infrastructure for data acquisition and validation of detection algorithms. The system was designed with SCADA architecture. Piezoresistive sensors were installed at the ends of the duct and Digital Signal Processors (DSPs) were used for sampling, storage and processing of data. The study was based on simulations of leaks through valves and search for patterns that characterize the occurrence of such phenomena

Detecção e diagnóstico de falhas não-supervisionados baseados em estimativa de densidade recursiva e classificador fuzzy auto-evolutivo

In this work, we propose a two-stage algorithm for real-time fault detection and identification of industrial plants. Our proposal is based on the analysis of selected features using recursive density estimation and a new evolving classifier algorithm. More specifically, the proposed approach for the detection stage is based on the concept of density in the data space, which is not the same as probability density function, but is a very useful measure for abnormality/outliers detection. This density can be expressed by a Cauchy function and can be calculated recursively, which makes it memory and computational power efficient and, therefore, suitable for on-line applications. The identification/diagnosis stage is based on a self-developing (evolving) fuzzy rule-based classifier system proposed in this work, called AutoClass. An important property of AutoClass is that it can start learning from scratch". Not only do the fuzzy rules not need to be prespecified, but neither do the number of classes for AutoClass (the number may grow, with new class labels being added by the on-line learning process), in a fully unsupervised manner. In the event that an initial rule base exists, AutoClass can evolve/develop it further based on the newly arrived faulty state data. In order to validate our proposal, we present experimental results from a level control didactic process, where control and error signals are used as features for the fault detection and identification systems, but the approach is generic and the number of features can be significant due to the computationally lean methodology, since covariance or more complex calculations, as well as storage of old data, are not required. The obtained results are significantly better than the traditional approaches used for comparison

Predição em modelos de tempo de falha acelerado com efeito aleatório para avaliação de riscos de falha em poços petrolíferos

We considered prediction techniques based on models of accelerated failure time with random e ects for correlated survival data. Besides the bayesian approach through empirical Bayes estimator, we also discussed about the use of a classical predictor, the Empirical Best Linear Unbiased Predictor (EBLUP). In order to illustrate the use of these predictors, we considered applications on a real data set coming from the oil industry. More speci - cally, the data set involves the mean time between failure of petroleum-well equipments of the Bacia Potiguar. The goal of this study is to predict the risk/probability of failure in order to help a preventive maintenance program. The results show that both methods are suitable to predict future failures, providing good decisions in relation to employment and economy of resources for preventive maintenance.

Modelo de tempo de falha acelerado com fração de cura : uma abordagem unificada

In this work we study the accelerated failure-time generalized Gamma regression models with a unified approach. The models attempt to estimate simultaneously the effects of covariates on the acceleration/deceleration of the timing of a given event and the surviving fraction. The method is implemented in the free statistical software R. Finally the model is applied to a real dataset referring to the time until the return of the disease in patients diagnosed with breast cancer