Rethinking the applicability domain analysis in QSAR models.

Notwithstanding the wide adoption of the OECD principles (or best practices) for QSAR modeling, disparities between in silico predictions and experimental results are frequent, suggesting that model predictions are often too optimistic. Of these OECD principles, the applicability domain (AD) estimation has been recognized in several reports in the literature to be one of the most challenging, implying that the actual reliability measures of model predictions are often unreliable. Applying tree-based error analysis workflows on 5 QSAR models reported in the literature and available in the QsarDB repository, i.e., androgen receptor bioactivity (agonists, antagonists, and binders, respectively) and membrane permeability (highest membrane permeability and the intrinsic permeability), we demonstrate that predictions erroneously tagged as reliable (AD prediction errors) overwhelmingly correspond to instances in subspaces (cohorts) with the highest prediction error rates, highlighting the inhomogeneity of the AD space. In this sense, we call for more stringent AD analysis guidelines which require the incorporation of model error analysis schemes, to provide critical insight on the reliability of underlying AD algorithms. Additionally, any selected AD method should be rigorously validated to demonstrate its suitability for the model space over which it is applied. These steps will ultimately contribute to more accurate estimations of the reliability of model predictions. Finally, error analysis may also be useful in "rational" model refinement in that data expansion efforts and model retraining are focused on cohorts with the highest error rates.

Open-source navigation system for tracking dissociated parts with multi-registration.

PURPOSE: During reconstructive surgery, knee and hip replacements, and orthognathic surgery, small misalignments in the pose of prosthesis and bones can lead to severe complications. Hence, the translational and angular accuracies are critical. However, traditional image-based surgical navigation lacks orientation data between structures, and imageless systems are unsuitable for cases of deformed anatomy. We introduce an open-source navigation system using a multiple registration approach that can track instruments, implants, and bones to precisely guide the surgeon in emulating a preoperative plan. METHODS: We derived the analytical error of our method and designed a set of phantom experiments to measure its precision and accuracy. Additionally, we trained two classification models to predict the system reliability from fiducial points and surface matching registration data. Finally, to demonstrate the procedure feasibility, we conducted a complete workflow for a real clinical case of a patient with fibrous dysplasia and anatomical misalignment of the right femur using plastic bones. RESULTS: The system is able to track the dissociated fragments of the clinical case and average alignment errors in the anatomical phantoms of [Formula: see text]  mm and [Formula: see text]. While the fiducial-points registration showed satisfactory results given enough points and covered volume, we acknowledge that the surface refinement step is mandatory when attempting surface matching registrations. CONCLUSION: We believe that our device could bring significant advantages for the personalized treatment of complex surgical cases and that its multi-registration attribute is convenient for intraoperative registration loosening cases.

Error Analysis of Accelerometer- and Magnetometer-Based Stationary Alignment.

This paper revisits the stationary attitude initialization problem, i.e., the stationary alignment, of Attitude and Heading Reference Systems (AHRSs). A detailed and comprehensive error analysis is proposed for four of the most representative accelerometer- and magnetometer-based stationary attitude determination methods, namely, the Three-Axis Attitude Determination (TRIAD), the QUaternion ESTimator (QUEST), the Factored Quaternion Algorithm (FQA), and the Arc-TANgent (ATAN). For the purpose of the error analysis, constant biases in the accelerometer and magnetometer measurements are considered (encompassing, hence, the effect of hard-iron magnetism), in addition to systematic errors in the local gravity and Earth magnetic field models (flux density magnitude, declination angle, and inclination angle). The contributions of this paper are novel closed-form formulae for the residual errors (normality, orthogonality, and alignment errors) developed in the computed Direction Cosine Matrices (DCM). As a consequence, analytical insight is provided into the problem, allowing us to properly compare the performance of the investigated alignment formulations (in terms of ultimate accuracy), as well as to remove some misleading conclusions reported in previous works. The adequacy of the proposed error analysis is validated through simulation and experimental results.

Thin-layer convective drying behaviour of brazilian peppertree leaves / Secagem em camada delgada de folhas de aroeira

Studies on the drying kinetics of medicinal, aromatic and spice plants are a necessary step towards establishing the combination of drying parameters that would not qualitatively and quantitatively alter the quality of the fresh product. The purpose of this study was to investigate the drying kinetics of Brazilian peppertree (Schinus terebinthifolius) leaves and to verify whether the theoretical diffusion and the semi-empirical Lewis drying models were capable of accurately predicting the drying curves of the product at 35, 40, and 45°C, with a dry air mass flow rate of 0.731 kg s-1 m-2. Leaves were collected at 0800 h, 1200 h and 1700 h. The goodness of fit between experimental and predicted values was based on the correlation coefficient, root mean square error, mean absolute percentage error, mean bias error, and fit index. Residual plot analysis was also considered in the selection of the most effective drying model. Temperature had a pronounced effect on mass transfer and drying rate decreased continuously during the course of drying. Leaf collection time had little influence on the drying kinetics. Effective moisture diffusivity was found to increase with temperature. The results indicated that the Lewis model was considered a better predictor of the thin-layer drying behaviour of Brazilian peppertree leaves than the theoretical model based on Fick's second law of diffusion.

Estudos sobre a cinética da secagem de plantas medicinais, aromáticas e condimentares são necessários para o estabelecimento de parâmetros operacionais de secagem de forma a não alterar significativamente a qualidade e o perfil fitoquímico dessas plantas. O objetivo do presente trabalho foi investigar a cinética da secagem das folhas da aroeira-vermelha (Schinus terebinthifolius), além de verificar se o modelo teórico de difusão e o modelo semi-empírico de Lewis são capazes de predizer com acurácia as curvas de secagem do produto a 35, 40 e 45°C, com fluxo de ar seco de 0,731 kg s-1 m-2. As folhas foram coletadas às 8:00, 12:00 e 17:00 h. O grau de adequação dos valores obtidos pelas curvas de secagem àqueles obtidos experimentalmente foi avaliado empregando-se o coeficiente de determinação, a raiz do erro quadrático médio, o erro percentual absoluto médio, o viés médio e o índice de ajuste. A análise da dispersão dos resíduos também foi utilizada na escolha do modelo de predição mais efetivo. Observou-se que a temperatura tem efeito significativo na transferência de massa e a taxa de secagem diminuiu continuamente ao longo da secagem. O horário de coleta das folhas não teve influência significativa sobre a cinética da secagem. A difusividade efetiva da água aumentou com o aumento da temperatura. Os resultados evidenciaram que o modelo de Lewis descreve com maior grau de acurácia a secagem de folhas de aroeira-vermelha que o modelo teórico baseado na Segunda Lei de Difusão de Fick.

Evidências de validade por processo de resposta no Cloze / Validity evidence based on response process in the Cloze test

O objetivo deste estudo foi explorar as diferenças qualitativas nos erros apresentados em um Teste de Cloze nas pontuações extremas de crianças e encontrar evidências de validade por processo de resposta. Participaram 277 alunos matriculados nos 3º, 4º e 5º anos do ensino fundamental público do Estado de São Paulo. Para a coleta de dados, que ocorreu de forma coletiva, foi empregado o teste de Cloze estruturado de forma tradicional, na qual se omitem todos os quintos vocábulos do texto e no local coloca-se um traço de tamanho proporcional ao da palavra omitida, bem como a correção verbatim. Os resultados evidenciaram evidências de validade baseadas no processo de resposta, indicando também divergências nas respostas entre os alunos que pontuaram menos e aqueles que obtiveram maiores pontuações. A discussão dos dados aponta para algumas implicações acerca dos processos cognitivos envolvidos na emissão das respostas das crianças.(AU)

This study aims to explore the errors differences presented in a Cloze test of kids' extreme punctuations and find evidences of the validity for answer process. 277 students from third, fourth and fifth grades of public education of São Paulo participated on the survey. For data collection, which occurred collectively, it was held a traditional Cloze test that substitutes the fifth words for a dash of the same size of the word hidden, as well as verbatim correction. Results showed evidences of validity based on answer process, indicating answer divergences between students with high punctuation and low punctuation. Data discussion points some implications about cognitive process involved on the emission of kids' answers.(AU)

Statistical Aspects of Near-Infrared Spectroscopy for the Characterization of Errors and Model Building.

Due to the complex nature of near-infrared (NIR) spectra, it is usually very difficult to provide quantitative interpretations of spectral data. As a consequence, careful building and validation of calibration models are of fundamental importance prior to development of useful applications of NIR technologies. For this reason, this work presents a statistical study about the NIR spectroscopy, analyzing the NIR behavior when the experimental conditions are changed. Near-infrared spectra were measured at different temperatures and stirring velocities for systems containing a pure solvent and a suspension of polymer powder in order to perform the error analysis. Then, mixtures of xylene and toluene were analyzed through NIR at different temperatures and stirring velocities and the obtained data were used to build calibration models with multivariate techniques. The results showed that the precision of the NIR measurements depends on the analytical conditions and that unavoidable fluctuations of spectral data (or spectral data variability) are strongly correlated, leading to full covariance matrices of spectral fluctuations, which has been surprisingly neglected during quantitative analyses. In particular, modeling of the xylene/toluene NIR data performed with different multivariate techniques revealed that the principal directions are not preserved when the real covariance matrix of measurement errors is taken into account.

Drying of pineapple slices in natura and pre-osmodehydrated in inverted sugar / Secagem de fatias de abacaxi in natura e pré-desidratadas osmoticamente em açúcar invertido

This research describes the drying kinetics and compares the convective drying rates of in natura and osmodehydrated pineapple slices in inverted sugar. The effective moisture diffusivity during air drying was estimated using Fick's second law of diffusion. The suitability of a theoretical liquid-diffusion model and seven semi-theoretical mathematical models for use in describing the experimental drying curves was also evaluated. Goodness of fit between experimental and predicted values was based on the root mean square error, mean absolute percentage error, mean bias error, agreement index, residual plot analysis and the principle of parsimony. Osmotic dehydration was conducted in 155, 310, and 465 mL L-1 osmotic solutions, at 40 and 50 ºC for 2 h at 60 rpm. Convective drying was performed in a tray cabinet dryer using heated ambient air at 60 ºC and 1.15 m s-1. Osmotic pretreatment facilitated water removal during the first hours of drying, a trend that was reversed towards the end of the process for samples osmodehydrated at the highest solution concentration. The effect of the osmotic pretreatments on drying rate was negligible at 40 C, but at 50 C the rate of moisture removal was more intense for samples in natura and osmodehydrated at the lowest solution concentration. Effective moisture diffusivity increased with temperature and solution concentration. The single-exponential, three-parameter semi-theoretical drying model gave the best predictions of the drying curves of pineapple slices both in natura and pre-osmodehydrated in inverted sugar.

O trabalho descreve a cinética de secagem e compara as taxas de secagem por convecção de fatias de abacaxi in natura e pré-desidratadas osmoticamente em açúcar invertido. A difusividade efetiva da água no interior do produto durante a secagem foi calculada empregando-se a Segunda Lei de Fick. Avalia, também, o grau de adequação de um modelo teórico de difusão de liquido e de sete modelos semi-teóricos na descrição das curvas experimentais de secagem. A desidratação osmótica foi realizada empregando-se soluções a 155, 310 e 465 mL L-1, a 40 e 50 ºC, sob agitação a 60 rpm e tempo de imersão de 2 h. A secagem por convecção foi feita em secador do tipo gabinete com bandejas, com ar à 60 ºC e 1,15 m s-1. O grau de ajuste dos modelos foi avaliado por meio da raiz do erro quadrático médio, do erro percentual absoluto médio, do viés médio, do índice de ajuste, pela análise da dispersão de resíduos e aplicando-se o princípio da parcimônia. O pré-tratamento osmótico facilitou a remoção de água durante as primeiras horas de secagem, comportamento que se reverteu ao final do processo para amostras desidratadas na solução mais concentrada. O efeito do pré-tratamento osmótico sobre a taxa de secagem foi desprezível a 40 ºC, no entanto, a 50 ºC, a taxa de remoção de água foi mais intensa para amostras in natura e pré-desidratadas nas soluções de menor concentração. A difusividade efetiva aumentou em função de aumentos na temperatura e na concentração da solução. O modelo exponencial simples de três parâmetros foi o que melhor descreveu as curvas de secagem por convecção de fatias de abacaxi in natura e pré-desidratadas osmoticamente em açúcar invertido

Análise de erros e compreensão de textos: comparações entre diferentes situações de leitura / Error Analysis and Reading Comprehension: Comparisons Between Different Reading Situations

O presente estudo analisou os erros apresentados por crianças com dificuldades de compreensão de textos em duas situações de leitura. As crianças do Grupo 1 realizaram a leitura interrompida de uma história e as do Grupo 2 realizaram a leitura sem interrupção. Após a leitura, as crianças responderam perguntas sobre informações inferenciais. A análise das respostas permitiu identificar quatro tipos de erros referentes à maneira de integrar informações intra e extratextuais. Apesar dos erros serem estáveis em ambas as situações, a leitura interrompida propiciou tentativas de estabelecimento de inferências mais eficientes do que a leitura sem interrupções. Os resultados contribuem para um entendimento psicológico das dificuldades de compreensão textual no que concerne ao estabelecimento de inferências, podendo gerar implicações educacionais.

This study analyzed errors presented by children with difficulties in reading comprehension in two reading conditions. Children in Group 1 were asked to read a story with interruptions, and those in Group 2 had to read the same story without any interruptions whatsoever. After reading, the children answered questions about information of an inferential nature. Analysis of the answers led to the identification of four types of errors, regarding the way intra and extra-textual information is integrated. Although the errors were stable in both situations, the interrupted reading appears to favor attempts to establish inferences. The results contribute to a psychological understanding of the difficulties related to reading comprehension, specifically in the establishment of inferences, with possible educational implications.

Análise de erros e compreensão de textos: comparações entre diferentes situações de leitura / Error Analysis and Reading Comprehension: Comparisons Between Different Reading Situations

O presente estudo analisou os erros apresentados por crianças com dificuldades de compreensão de textos em duas situações de leitura. As crianças do Grupo 1 realizaram a leitura interrompida de uma história e as do Grupo 2 realizaram a leitura sem interrupção. Após a leitura, as crianças responderam perguntas sobre informações inferenciais. A análise das respostas permitiu identificar quatro tipos de erros referentes à maneira de integrar informações intra e extratextuais. Apesar dos erros serem estáveis em ambas as situações, a leitura interrompida propiciou tentativas de estabelecimento de inferências mais eficientes do que a leitura sem interrupções. Os resultados contribuem para um entendimento psicológico das dificuldades de compreensão textual no que concerne ao estabelecimento de inferências, podendo gerar implicações educacionais.(AU)

This study analyzed errors presented by children with difficulties in reading comprehension in two reading conditions. Children in Group 1 were asked to read a story with interruptions, and those in Group 2 had to read the same story without any interruptions whatsoever. After reading, the children answered questions about information of an inferential nature. Analysis of the answers led to the identification of four types of errors, regarding the way intra and extra-textual information is integrated. Although the errors were stable in both situations, the interrupted reading appears to favor attempts to establish inferences. The results contribute to a psychological understanding of the difficulties related to reading comprehension, specifically in the establishment of inferences, with possible educational implications.(AU)

SU-E-T-147: Film Dosimetry Verification for TSE Using An Epson Scanner.

PURPOSE: To commission and verify an Epson scanner for film dosimetry for total skin electron beam therapy (TSEB). METHODS: Use data from an IBA PPC40 parallel-plate ion chamber and Sun Nuclear QED skin diode detectors as standard; we have made comparisons to the film measurement using Kodak XV films. Hurter-Driffield (HD) curve are established for 6 MeV total skin electron beams at a source-to-surface distance (SSD) of 5 m. Also HD curves are built for 6 MeV at a 100 cm SSD. Dose profiles for a series of oblique incident large electron fields are measured using the film for approximately 80 cGy dose delivered at the peak. The film is then scanned using two scanners, an Epson expression 10000 XL and a Vidar VXR-16 Dosimetry Pro. The optimal scanning conditions (e.g., dot per pixel size, internal color correction scheme) are chosen for the Epson scanner. Matlab is then used to analyze the optical density (OD) of the scanned films. A transmission densitometer made by Tobias Associates transmission is used to analyze the films to give a classical standard. RESULTS: The analysis of the Epson scanner is presented in two forms: one with and one without the HD correction from the established HD curve. The error analysis gives an uncertainty of 5% without the HD correction. An improved result of approximately 3% is found when an HD correction is applied to the analysis. CONCLUSIONS: A simple Epson scanner satisfies the commissioning standards for TSEB when an HD curve correction is applied.