Advancing aircraft engine RUL predictions: an interpretable integrated approach of feature engineering and aggregated feature importance.

In this study, we present a comprehensive approach for predicting the remaining useful life (RUL) of aircraft engines, incorporating advanced feature engineering, dimensionality reduction, feature selection techniques, and machine learning models. The process begins with a rolling time series window, followed by the extraction of a multitude of statistical features, and the application of principal component analysis for dimensionality reduction. We utilize a variety of feature selection methods, such as Genetic Algorithm, Recursive Feature Elimination, Least Absolute Shrinkage and Selection Operator Regression, and Feature Importances from a Random Forest model. As a significant contribution, we introduce the novel aggregated feature importances with cross-validation (AFICv) technique, which ranks features based on their mean importance. We establish a selection criterion that retains features with a cumulative mean sum equal to 70%, thereby reducing the complexity of machine learning models and enhancing their generalizability. Four machine learning regression models-Natural and Extreme Gradient Boosting, Random Forest, and Multi-Layer Perceptron-were employed to evaluate the effectiveness of the selected features. The performance of our proposed method is assessed by the evaluation metrics Root Mean Square Error (RMSE) and R2 Score, and also considered within-interval percentages and relative accuracy metrics. Importantly, a novel PCA interpretability was introduced to provide real-world context and enhance the utility of our findings for domain experts. Our results indicate that the proposed AFICv technique efficiently achieves competitive performance across the Commercial Modular Aero-Propulsion System Simulation (C-MAPSS) sub-datasets using a significantly smaller subset of features, thus contributing to a more effective and interpretable RUL prediction methodology for aircraft engines.

Pesquisa de anticorpos anti-endomísio no laboratório de imunopatologia da UFPR: dez anos de experiência na triagem de doença celíaca em pacientes, grupos de risco e populações / Antiendomysium antibodies evaluation in the laboratory of immunopathology of the UFPR: ten years of experience in the screening of celiac disease in patients, groups ato risk and in the general population

O laboratório de imunopatologia do Hospital de Clínicas da Universidade Federal do Paraná, através da pesquisa do anticorpo anti-endomísio (EmA-IgA), tem contribuído ao longo dos últimos dez anos com a triagem e diagnóstico diferencial da doença celíaca (DC) em pacientes, grupos de risco e populações do sul do Brasil. No presente estudo, tem-se uma síntese das investigações mais relevantes que foram realizadas e que possibilitaram diagnóstico da doença e no monitoramento da dieta isenta de glúten, assim como sua correlação com os anticorpos anti-transgluta-minase e o grau de lesão na mucosa intestinal. O EmA-IgA tem sido avaliado por imunofluorescência indireta, utilizando cordão umbilical humano como substrato, e conjugado fluorescente anti-IgA. O compilamento de dados dos estudos com familiares de celíacos (n=200), pacientes com síndrome de Down (n=150), diabetes mellitus (n=104), cardiomiopatias (n=74), artrite reumatóide (n=85), doadores de banco de sangue (n=2000) e indivíduos da população sadia (n=180), permitiu demonstrar significativa diferença na freqüência do EmA-IgA no grupo de familiares (p<0,001), pacientes síndrome de Down (p=0.0024) e diabetes mellitus (p<0.001), em relação à população sadia. Os dados obtidos nos últimos dez anos de pesquisa nessa área indicam os familiares de celíacos como ogrupo de maior risco ao desenvolvimento da doença, e ressaltam a importância de screenings periódicos para DC em pacientes com doenças autoimunes e/ou outras afecções.

Genetic variability of hepatitis A virus strain HAF-203 isolated in Brazil and expression of the VP1 gene in Escherichia coli.

The hepatitis A virus (HAV) HAF-203 strain was isolated from an acute case of HAV infection. The primary isolation of HAF-203 in Brazil and its adaptation to the FRhK-4 cell lineage allowed the production of large amounts of viral particles enabling molecular characterization of the first HAV isolate in Brazil. The aim of our study was to determine the nucleotide sequence of the HAF-203 strain genome, compare it to other HAV genomes and highlight its genetic variability. The complete nucleotide sequence of the HAF-203 strain (7472 nucleotides) was compared to those obtained earlier by others for other HAV isolates. These analyses revealed 19 HAF-specific nucleotide sequence differences with 10 amino acid substitutions. Most of the non-conservative changes were located at VP1, 2C, and 3D genes, but the 3B region was the most variable. The availability of HAF-203 complementary DNA was useful for the production of the recombinant VP1 protein, which is a major determinant of viral infectivity. This recombinant protein was shown by enzyme-linked immunoassay and blotting, to be immunogenic and resemble the native protein, therefore suggesting its value as a reagent for incorporation into diagnostic tests.

Genetic variability of hepatitis A virus strain HAF-203 isolated in Brazil and expression of the VP1 gene in Escherichia coli

The hepatitis A virus (HAV) HAF-203 strain was isolated from an acute case of HAV infection. The primary isolation of HAF-203 in Brazil and its adaptation to the FRhK-4 cell lineage allowed the production of large amounts of viral particles enabling molecular characterization of the first HAV isolate in Brazil. The aim of our study was to determine the nucleotide sequence of the HAF-203 strain genome, compare it to other HAV genomes and highlight its genetic variability. The complete nucleotide sequence of the HAF-203 strain (7472 nucleotides) was compared to those obtained earlier by others for other HAV isolates. These analyses revealed 19 HAF-specific nucleotide sequence differences with 10 amino acid substitutions. Most of the non-conservative changes were located at VP1, 2C, and 3D genes, but the 3B region was the most variable. The availability of HAF-203 complementary DNA was useful for the production of the recombinant VP1 protein, which is a major determinant of viral infectivity. This recombinant protein was shown by enzyme-linked immunoassay and blotting, to be immunogenic and resemble the native protein, therefore suggesting its value as a reagent for incorporation into diagnostic tests.

In situ hybridization of hepatitis C virus RNA in liver cells of an experimentally infected rhesus macaque.

The liver tissue of a rhesus macaque inoculated with hepatitis C virus (HCV) has been analyzed for the presence of HCV RNA using the technique of in situ hybridization, both at light and electron microscopy levels. The animal was inoculated by the intrasplenic route using a HCV infected autogenic hepatocyte transplant. The serum sample used to infect the hepatocyte cells was characterized by polymerase chain reaction technique and shown to be positive for HCV RNA, genotype 3 with 10(7) RNA copies/ml. In situ hybridization was performed using a complementary negative strand probe made with the specific primer. We were able to detect and localize viral RNA in altered membranes of the rough endoplasmic reticulum of infected liver cells, showing evidence of virus replication in vivo.

In situ hybridization of hepatitis C virus RNA in liver cells of an experimentally infected rhesus macaque

The liver tissue of a rhesus macaque inoculated with hepatitis C virus (HCV) has been analyzed for the presence of HCV RNA using the technique of in situ hybridization, both at light and electron microscopy levels. The animal was inoculated by the intrasplenic route using a HCV infected autogenic hepatocyte transplant. The serum sample used to infect the hepatocyte cells was characterized by polymerase chain reaction technique and shown to be positive for HCV RNA, genotype 3 with 10(7) RNA copies/ml. In situ hybridization was performed using a complementary negative strand probe made with the specific primer. We were able to detect and localize viral RNA in altered membranes of the rough endoplasmic reticulum of infected liver cells, showing evidence of virus replication in vivo.

Characterization of hepatitis A virus isolates from subgenotypes IA and IB in Rio de Janeiro, Brazil.

Hepatitis A virus (HAV) isolates from around the world have been classified into seven genotypes (I-VII). Most human strains belong to genotype I, which has been divided into two subgenotypes, A and B. South America has provided a small number of strains studied at the genome level. In the present study, IgM anti-HAV antibodies were detected in 116 out of 250 (46%) serum samples collected from consecutive patients with acute hepatitis referred to the Brazilian Reference Center for Viral Hepatitis, Rio de Janeiro. Viral RNA were extracted from all 250 samples and submitted to a reverse transcription-polymerase chain reaction (RT-PCR) assay designed to amplify a genome segment in the VP1/2A junction region. HAV RNA was detected in 54/116 (47%) and 17/134 (13%) IgM anti-HAV-positive and -negative sera, respectively. In addition, HAV RNA was detected in 17/35 (49%) IgM anti-HAV-positive sera that had been collected at a day care center where cases of acute hepatitis were being observed for 3 months. Nucleotide sequences (168 bp) of PCR products were determined for 30 HAV isolates. Phylogenetic analysis showed that 21 belonged to subgenotype IB, while 9 were of subgenotype IA. Interestingly, a concomitant circulation of isolates from subgenotypes IA and IB was observed in the day care center.

Studies on transmission of hepatitis A virus to squirrel monkeys.

Non-human primates have been playing an essential role in the study of hepatitis A virus (HAV) biology, pathogenesis and for testing candidate HAV vaccines. This study was to determine the suitability of squirrel monkeys (Saimiri sciureus) as animal model for HAV infection. Animals were inoculated, either intragastrically or intravenously, with a Brazilian HAV isolate (HAF-203). Alanine aminotransferase (ALT) and anti-HAV antibodies (IgM and total) were monitored. Feces were daily collected for HAV antigen and HAV RNA detection. Samples of liver tissue were obtained by biopsy before inoculation at peak ALT levels and/or when anti-HAV antibodies developed, and at necropsy for morphological examination. Monkeys inoculated by the intravenous route rapidly developed significant elevations of serum ALT, anti-HAV antibodies, and liver histologic changes, while the only evidence of HAV infection in intragastrically inoculated animals was the seroconversion. Moreover, squirrel monkeys excreted very low levels of HAV detectable in only few fecal samples after amplification by RT-PCR, different from humans and other non-human primate species that eliminate large quantities of virus during the late incubation period. The unusual onset of hepatitis A in experimentally infected squirrel monkeys represent an important obstacle for its use as animal model for the study of this viral infection. However, they can represent a valuable tool for the obtention of hyperimmune sera for HAV, in the view of the very high titer of anti-HAV developed (105) 24 days after a single intravenous inoculation.

Ocorrência de hepatites näo-A näo-B em unidade de hemodiálise / Occurrence of non-A non-B hepatitis in hemodyalisis unit

A monitorizaçäo mensal de alanina aminotransferase (ALT) sérica de pacientes em hemodiálise e os testes sorológicos para exclusöes de infecçöes por vírus da hepatite A (HAV), vírus da hepatie B (HBV), citomegalovirus (CMV) e vírus Epstein-Barr (EBV), permitiu-nos identificar 11 casos de hepatites näo-B em 111 indivíduos avaliados durante o período de 12 meses e acompanhados por 2 anos. Foram observados 3 padröes de atividade de ALT: elevaçäo em pico monofásico em 2, bifásico ou polifásico em 6 e em platô em 3 pacientes. Individuos com padräo monofásico exibiram os níveis amis elevados de ALT. Cinco pacientes apresentaram normalizaçäo bioquímica persistente 4,8 meses em média após o início da elevaçäo aguda e seis evoluíram com ascensäo crônica de ALT durante o período de estudo. A hepatite näo-A, näo-B foi, predominantemente, assintomática e anictérica, sempre antecedida por transfusöes sangüíneas e com maior incidência nos seis primeiros meses de terapia dialítica dos pacientes