RESUMO

This study aimed to evaluate the reliability of an age estimation method based on the pulp/tooth area ratio by assessing intra- and inter-examiner agreement across five observers at different intervals. Using the same X-ray device and technical parameters, 96 digital periapical X-ray images of upper and lower canines were obtained from 28 deceased people in Central America, whose age at death ranged from 19 to 49 years. Excellent and good agreement of results were achieved, and there were no statistically significant differences. The R2 value for upper teeth (54.0%) was higher than the R2 value for lower teeth (45.7%). The highest intraclass correlation coefficient value was 0.995 (0.993-0.997) and the lowest 0.798 (0.545-0.895). Inter-examiner agreement was high with values of 0.975 (0.965-0.983) and 0.927 (0.879-0.955). This method is adequate for assessing age in missing and unidentified people, including victims of mass disasters.

RESUMO

The growing use of Unmanned Aerial Vehicles (UAVs) raises the need to improve their autonomous navigation capabilities. Visual odometry allows for dispensing positioning systems, such as GPS, especially on indoor flights. This paper reports an effort toward UAV autonomous navigation by proposing a translational velocity observer based on inertial and visual measurements for a quadrotor. The proposed observer complementarily fuses available measurements from different domains and is synthesized following the Immersion and Invariance observer design technique. A formal Lyapunov-based observer error convergence to zero is provided. The proposed observer algorithm is evaluated using numerical simulations in the Parrot Mambo Minidrone App from Simulink-Matlab.

RESUMO

INTRODUCTION: Despite being the most used exam today, few studies have evaluated the accuracy of findings on non-contrast magnetic resonance imaging (MRI). The primary objective of the study was to evaluate the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of non-contrast MRI findings in frozen shoulder, isolated and in combination. The secondary objectives were to define the interobserver and intraobserver agreement of the assessments and the odds ratio for frozen shoulder because of the various findings of MRI. METHODS: A retrospective diagnostic accuracy study comparing non-contrast MRI findings between the frozen shoulder group and the control group. Sensitivity, specificity, positive and negative predictive value, accuracy, odds ratio, interobserver and intraobserver agreement were calculated for each finding and their possible associations. RESULTS: The hyperintensity on capsule in the axillary recess presented 84% sensitivity, 94% specificity, and 89% accuracy. The obliteration of the subcoracoid fat triangle in the rotator interval had sensitivity 34%, specificity 82% and accuracy 58%. For coracohumeral ligament thickness ≥ 2 mm had specificity 66%, 48% specificity and 57% accuracy. Capsule thickness in the axillary recess ≥ 4 mm resulted in 54% sensitivity, 82% specificity, and 68% accuracy. Regarding interobserver agreement, only the posteroinferior and posterosuperior quadrants showed moderate results, and all the others showed strong reliability. The odds ratio for hyperintensity in the axillary recess was 82.3 for frozen shoulder. The association of these findings increased specificity (95%). CONCLUSION: The accuracy of non-contrast magnetic resonance imaging is high for diagnosing frozen shoulder, especially when evaluating the hyperintensity of the axillary recess. The exam has high reliability and reproducibility. The presence of an association of signs increases the specificity of the test. LEVEL OF EVIDENCE: Level III, study of diagnostic test.

Assuntos

RESUMO

O propósito deste artigo é refletir sobre os conceitos de transferência e contratransferência, articulando-os com a dimensão clínica do lugar do observador no trabalho em grupos terapêuticos. Inicialmente, será feito um percurso histórico sobre tais conceitos na psicanálise. Posteriormente, a noção de transferência será discutida como um vínculo que pode se manifestar pela via da expressão corporal e sensorialidade, enquanto a contratransferência será analisada a partir do campo da intersubjetividade. Esses aspectos serão ilustrados por duas vinhetas clínicas

This paper reflects on the concepts of transference and countertransference in articulation with the clinical dimension of the observer's place in therapeutic groups. After a brief historical overview of these concepts in psychoanalysis, the notion of transference is discussed as a link that can manifest itself via bodily and sensorially. Countertransference, in turn, will be analyzed based on intersubjectivity. These aspects will be illustrated by two clinical vignettes

Cet article reflète aux concepts de transfert et de contre-transfert en articulation avec la dimension clinique de la place de l'observateur dans les groupes thérapeutiques. D'après un aperçu historique de ces concepts en psychanalyse, on discute la notion de transfert en tant que lien qui peut se manifester par l'expression corporelle et la sensorialité. Le contre-transfert, à son tour, sera analysé à partir du domaine de l'intersubjectivité. Ces aspects seront illustrés par deux vignettes cliniques

El propósito de este artículo es reflexionar sobre los conceptos de transferencia y contratransferencia articulándolos con la dimensión clínica del lugar del observador en el trabajo con grupos terapéuticos. Inicialmente, se hará un recorrido histórico sobre tales conceptos en el psicoanálisis. Posteriormente, la noción de transferencia será discutida como vínculo que puede manifestarse por la expresión corporal y la sensorialidad, mientras que la contratransferencia será analizada a partir del campo de la intersubjetividad. Estos aspectos serán ilustrados por dos viñetas clínicas

Assuntos

RESUMO

Objective: To assess the reliability of phase-sensitive inversion recovery (PSIR) magnetic resonance imaging (MRI) and its accuracy for determining the topography of demyelinating cortical lesions in patients with multiple sclerosis (MS). Materials and Methods: This was a cross-sectional study conducted at a tertiary referral center for MS and other demyelinating disorders. We assessed the agreement among three raters for the detection and topographic classification of cortical lesions on fluid-attenuated inversion recovery (FLAIR) and PSIR sequences in patients with MS. Results: We recruited 71 patients with MS. The PSIR sequences detected 50% more lesions than did the FLAIR sequences. For detecting cortical lesions, the level of interrater agreement was satisfactory, with a mean free-response kappa (κFR) coefficient of 0.60, whereas the mean κFR for the topographic reclassification of the lesions was 0.57. On PSIR sequences, the raters reclassified 366 lesions (20% of the lesions detected on FLAIR sequences), with excellent interrater agreement. There was a significant correlation between the total number of lesions detected on PSIR sequences and the Expanded Disability Status Scale score (ρ = 0.35; p < 0.001). Conclusion: It seems that PSIR sequences perform better than do FLAIR sequences, with clinically satisfactory interrater agreement, for the detection and topographic classification of cortical lesions. In our sample of patients with MS, the PSIR MRI findings were significantly associated with the disability status, which could influence decisions regarding the treatment of such patients.

Objetivo: Avaliar a confiabilidade da sequência PSIR e sua precisão no diagnóstico topográfico de lesões corticais desmielinizantes em pacientes com esclerose múltipla (EM). Materiais e Métodos: Estudo transversal realizado em centro de referência terciário para EM e distúrbios desmielinizantes. Avaliamos a concordância entre três avaliadores na identificação e classificação topográfica de lesões corticais na ressonância magnética de pacientes com EM, utilizando as sequências FLAIR e PSIR. Resultados: Foram incluídos 71 pacientes com EM. Em PSIR detectou-se 1,5× mais lesões do que em FLAIR, com concordância satisfatória entre examinadores na identificação de lesões corticais, com coeficiente kappa de resposta livre (κFR) = 0,60, e na reclassificação topográfica das lesões, com κFR médio = 0,57. Os avaliadores reclassificaram 366 lesões em PSIR (20% das lesões detectadas em FLAIR), com excelente concordância. Houve correlação significativa do total de lesões detectadas em PSIR e o escore da escala de incapacidade EDSS (ρ = 0,35; p < 0,001). Conclusão: PSIR mostrou-se superior na detecção de lesões corticais e na classificação topográfica destas em comparação ao FLAIR, com concordâncias entre examinadores clinicamente satisfatórias. A associação significativa entre o número de lesões corticais em PSIR e o grau de incapacidade dos pacientes pode influenciar em decisões terapêuticas.

RESUMO

This paper is concerned with fault reconstruction based on sliding mode observers; its contribution is twofold: on the one hand, it develops a novel sliding mode observer whose nominal system is nonlinear, thus relaxing former limitations on the subject, namely, rank restrictions, linear outputs, and conservative bounds; on the other hand, based on the referred sliding mode observer, a novel robust fault reconstruction scheme is constructed which can solve a variety of problems that former methodologies cannot treat. Nonlinearities are cast as convex expressions, which enables obtaining design conditions in the form of linear matrix inequalities. Examples are provided to compare the proposal with former methodologies, thus highlighting the contributions.

RESUMO

Hemoglobin and hematocrit are parameters widely used. They can be obtained from an automated hematology analyzer or from an arterial blood gas analyzer. Its variability is shown in the article "Variability of hemoglobin and hematocrit determined in blood gas equipment." Clinical and statistical information requested is extended for a better understanding of the article and its conclusions. It is suggested to carry out an analysis of variability in parameters and laboratory equipment.

La hemoglobina y el hematocrito son parámetros de amplio uso. Pueden ser obtenidos de un analizador automatizado de hematología o de un analizador de gases arteriales. Su variabilidad se muestra en el artículo "Variabilidad de la hemoglobina y hematocrito determinados en equipo de gases sanguíneos". Se amplía la información clínica y estadística solicitada para la mejor comprensión del trabajo y sus conclusiones. Se sugiere hacer un análisis de variabilidad en parámetros y equipos de laboratorios.

Assuntos

RESUMO

BACKGROUND: The training needed for doing obstetric ultrasounds is rarely reported. The aim of this study was to determine whether the training of the ultrasonographer influences the prenatal diagnostic certainty of some congenital malformations. METHODS: We conducted a retrospective evaluation of antepartum sonographic findings of newborn infants found ultimately to have a congenital anomaly in a tertiary level pediatric reference center. Data were collected on admission for consecutive patients at a tertiary-level pediatric reference center. The mother´s pregnancy and birth demographic variables and those of the prenatal ultrasound (PUS) were analyzed and correlated with the final diagnosis. RESULTS: Sixty-seven neonates were included. All cases underwent PUS with a mean of 4.6. Prenatal diagnosis was established in 24 cases (35.8%). Thirteen surgical anomalies were detected, particularly anorectal malformation and gastroschisis. The accuracy of PUS was associated with the training of the physician performing the PUS, whereby PUS with the greatest accuracy were performed by gynecologists and maternal-fetal specialists against radiologists and general practitioners (p = 0.005). Patients without an accurate prenatal diagnosis had a greater risk of presenting comorbidities (relative risk [RR]: 1.65, p = < 0.001, 95% confidence interval [CI]: 1.299-2.106). CONCLUSIONS: In our setting, prenatal diagnosis of these malformations is directly determined by the training of the person performing the ultrasound.

INTRODUCCIÓN: Con poca frecuencia se ha reportado el entrenamiento necesario para realizar ultrasonido (US) obstétrico. El objetivo de este estudio fue determinar si el entrenamiento del ultrasonografista influye en la certeza del diagnóstico prenatal de algunas malformaciones congénitas. MÉTODOS: Se llevó a cabo una evaluación retrospectiva de los hallazgos ultrasonográficos prenatales de neonatos que tuvieron malformaciones congénitas en un hospital de referencia pediátrico de tercer nivel. Se realizó al ingreso de neonatos consecutivos en un hospital de referencia de tercer nivel. Se recolectaron y analizaron datos del embarazo y alumbramiento, así como los de los ultrasonidos prenatales (USP) correlacionando con el diagnóstico final. RESULTADOS: Se incluyeron 67 neonatos. Todos tuvieron USP con media de 4.6. Se realizó diagnóstico prenatal en 24 casos (35.8%). Se detectaron 13 malformaciones congénitas, predominando malformación anorectal gastrosquisis. La certeza del USP se asoció con el entrenamiento del individuo que realizó el US y la mayor certeza se encontró cuando lo realizaron ginecólogos y especialistas materno-fetales contra radiólogos y médicos generales (p = 0.005). Los pacientes sin diagnóstico prenatal certero tuvieron mayor riesgo de presentar comorbilidades (riesgo relativo [RR]: 1.65, p = < 0.001, 95% intervalo de confianza [CI]: 1.299-2.106). CONCLUSIONES: En nuestro medio, el diagnóstico prenatal de estas malformaciones está determinado directamente por el entrenamiento de la persona que realiza el ultrasonido.

Assuntos

RESUMO

Abstract Background: The training needed for doing obstetric ultrasounds is rarely reported. The aim of this study was to determine whether the training of the ultrasonographer influences the prenatal diagnostic certainty of some congenital malformations. Methods: We conducted a retrospective evaluation of antepartum sonographic findings of newborn infants found ultimately to have a congenital anomaly in a tertiary level pediatric reference center. Data were collected on admission for consecutive patients at a tertiary-level pediatric reference center. The mother´s pregnancy and birth demographic variables and those of the prenatal ultrasound (PUS) were analyzed and correlated with the final diagnosis. Results: Sixty-seven neonates were included. All cases underwent PUS with a mean of 4.6. Prenatal diagnosis was established in 24 cases (35.8%). Thirteen surgical anomalies were detected, particularly anorectal malformation and gastroschisis. The accuracy of PUS was associated with the training of the physician performing the PUS, whereby PUS with the greatest accuracy were performed by gynecologists and maternal-fetal specialists against radiologists and general practitioners (p = 0.005). Patients without an accurate prenatal diagnosis had a greater risk of presenting comorbidities (relative risk [RR]: 1.65, p = < 0.001, 95% confidence interval [CI]: 1.299-2.106). Conclusions: In our setting, prenatal diagnosis of these malformations is directly determined by the training of the person performing the ultrasound.

Resumen Introducción: Con poca frecuencia se ha reportado el entrenamiento necesario para realizar ultrasonido (US) obstétrico. El objetivo de este estudio fue determinar si el entrenamiento del ultrasonografista influye en la certeza del diagnóstico prenatal de algunas malformaciones congénitas. Métodos: Se llevó a cabo una evaluación retrospectiva de los hallazgos ultrasonográficos prenatales de neonatos que tuvieron malformaciones congénitas en un hospital de referencia pediátrico de tercer nivel. Se realizó al ingreso de neonatos consecutivos en un hospital de referencia de tercer nivel. Se recolectaron y analizaron datos del embarazo y alumbramiento, así como los de los ultrasonidos prenatales (USP) correlacionando con el diagnóstico final. Resultados: Se incluyeron 67 neonatos. Todos tuvieron USP con media de 4.6. Se realizó diagnóstico prenatal en 24 casos (35.8%). Se detectaron 13 malformaciones congénitas, predominando malformación anorectal gastrosquisis. La certeza del USP se asoció con el entrenamiento del individuo que realizó el US y la mayor certeza se encontró cuando lo realizaron ginecólogos y especialistas materno-fetales contra radiólogos y médicos generales (p = 0.005). Los pacientes sin diagnóstico prenatal certero tuvieron mayor riesgo de presentar comorbilidades (riesgo relativo [RR]: 1.65, p = < 0.001, 95% intervalo de confianza [CI]: 1.299-2.106). Conclusiones: En nuestro medio, el diagnóstico prenatal de estas malformaciones está determinado directamente por el entrenamiento de la persona que realiza el ultrasonido.

RESUMO

BACKGROUND: Pediatric hepatic steatosis is a global public health concern, as an increasing number of children are affected by this condition. Liver biopsy is the gold standard diagnostic method; however, this procedure is invasive. Magnetic resonance imaging (MRI)-derived proton density fat fraction has been accepted as an alternative to biopsy. However, this method is limited by cost and availability. Ultrasound (US) attenuation imaging is an upcoming tool for noninvasive quantitative assessment of hepatic steatosis in children. A limited number of publications have focused on US attenuation imaging and the stages of hepatic steatosis in children. OBJECTIVE: To analyze the usefulness of ultrasound attenuation imaging for the diagnosis and quantification of hepatic steatosis in children. MATERIAL AND METHODS: Between July and November 2021, 174 patients were included and divided into two groups: group 1, patients with risk factors for steatosis (n = 147), and group 2, patients without risk factors for steatosis (n = 27). In all cases, age, sex, weight, body mass index (BMI), and BMI percentile were determined. B-mode US (two observers) and US attenuation imaging with attenuation coefficient acquisition (two independent sessions, two different observers) were performed in both groups. Steatosis was classified into four grades (0: absent, 1: mild, 2: moderate and 3: severe) using B-mode US. Attenuation coefficient acquisition was correlated with steatosis score according to Spearman's correlation. Attenuation coefficient acquisition measurements' interobserver agreement was assessed using intraclass correlation coefficients (ICC). RESULTS: All attenuation coefficient acquisition measurements were satisfactory without technical failures. The median values for group 1 for the first session were 0.64 (0.57-0.69) dB/cm/MHz and 0.64 (0.60-0.70) dB/cm/MHz for the second session. The median values for group 2 for the first session were 0.54 (0.51-0.56) dB/cm/MHz and 0.54 (0.51-0.56) dB/cm/MHz for the second. The average attenuation coefficient acquisition was 0.65 (0.59-0.69) dB/cm/MHz for group 1 and 0.54 (0.52-0.56) dB/cm/MHz for group 2. There was excellent interobserver agreement at 0.94 (95% CI 0.92-0.96). There was substantial agreement between both observers (κ = 0.77, with a P < 0.001). There was a positive correlation between ultrasound attenuation imaging and B-mode scores for both observers (r = 0.87, P < 0.001 for observer 1; r = 0.86, P < 0.001 for observer 2). Attenuation coefficient acquisition median values were significantly different for each steatosis grade (P < 0.001). In the assessment of steatosis by B-mode US, the agreement between the two observers was moderate (κ = 0.49 and κ = 0.55, respectively, with a P < 0.001 in both cases). CONCLUSION: US attenuation imaging is a promising tool for the diagnosis and follow-up of pediatric steatosis, which provides a more repeatable form of classification, especially at low levels of steatosis detectable in B-mode US.

Assuntos

RESUMO

Interviewed health care workers to determine whether they had noticed a silent hand hygiene observer, thereby determining the legitimacy of the silent observers. Data supported the observers were typically unseen, and potential observer bias had a negligible role in hand hygiene compliance.

Assuntos

RESUMO

INTRODUCTION: The proprioception plays an important role in the stability of the shoulder joint. However, clinical practice lacks reliable and user-friendly tools. OBJECTIVES: To evaluate the intra- and inter-rater reliability of the Laser-Pointer assisted Angle Reproduction Test (LP-ART), to analyze the difference in proprioception between the symptomatic and asymptomatic shoulders, and to investigate if there is a correlation between the LP-ART and the pain intensity assessed by 11-point Numerical Rating Pain Scale (NRPS) and the level of shoulder disability and pain assessed by the Disability Index and Shoulder Pain (SPADI - BR). METHODS: Fifty patients (age = 56.2 ± 10.4 years) performed the LP-ART at 90° of shoulder flexion. RESULTS: The intra and interrater reliability of the LP-ART measurements was moderate (Intraclass Correlation Coefficient2,3 = 0.41 to 0.65) for both shoulders, symptomatic and asymptomatic. There was no difference in the absolute angular deviation between shoulders (mean difference of 0.4°, P = .581). The absolute angular deviation was not significantly correlated with the pain intensity (rs = 0.007, P = .962) and the SPADI - BR (rs = 0.022, P = .881). CONCLUSION: The LP-ART measurement showed moderate reliability in participants with subacromial pain syndrome. The active joint position sense was not different between symptomatic and asymptomatic shoulders, and there was no correlation between proprioception and the pain intensity and shoulder pain and disability level.

Assuntos

RESUMO

Abstract Objective: To assess the reliability of phase-sensitive inversion recovery (PSIR) magnetic resonance imaging (MRI) and its accuracy for determining the topography of demyelinating cortical lesions in patients with multiple sclerosis (MS). Materials and Methods: This was a cross-sectional study conducted at a tertiary referral center for MS and other demyelinating disorders. We assessed the agreement among three raters for the detection and topographic classification of cortical lesions on fluid-attenuated inversion recovery (FLAIR) and PSIR sequences in patients with MS. Results: We recruited 71 patients with MS. The PSIR sequences detected 50% more lesions than did the FLAIR sequences. For detecting cortical lesions, the level of interrater agreement was satisfactory, with a mean free-response kappa (κFR) coefficient of 0.60, whereas the mean κFR for the topographic reclassification of the lesions was 0.57. On PSIR sequences, the raters reclassified 366 lesions (20% of the lesions detected on FLAIR sequences), with excellent interrater agreement. There was a significant correlation between the total number of lesions detected on PSIR sequences and the Expanded Disability Status Scale score (ρ = 0.35; p < 0.001). Conclusion: It seems that PSIR sequences perform better than do FLAIR sequences, with clinically satisfactory interrater agreement, for the detection and topographic classification of cortical lesions. In our sample of patients with MS, the PSIR MRI findings were significantly associated with the disability status, which could influence decisions regarding the treatment of such patients.

Resumo Objetivo: Avaliar a confiabilidade da sequência PSIR e sua precisão no diagnóstico topográfico de lesões corticais desmielinizantes em pacientes com esclerose múltipla (EM). Materiais e Métodos: Estudo transversal realizado em centro de referência terciário para EM e distúrbios desmielinizantes. Avaliamos a concordância entre três avaliadores na identificação e classificação topográfica de lesões corticais na ressonância magnética de pacientes com EM, utilizando as sequências FLAIR e PSIR. Resultados: Foram incluídos 71 pacientes com EM. Em PSIR detectou-se 1,5× mais lesões do que em FLAIR, com concordância satisfatória entre examinadores na identificação de lesões corticais, com coeficiente kappa de resposta livre (κFR) = 0,60, e na reclassificação topográfica das lesões, com κFR médio = 0,57. Os avaliadores reclassificaram 366 lesões em PSIR (20% das lesões detectadas em FLAIR), com excelente concordância. Houve correlação significativa do total de lesões detectadas em PSIR e o escore da escala de incapacidade EDSS (ρ = 0,35; p < 0,001). Conclusão: PSIR mostrou-se superior na detecção de lesões corticais e na classificação topográfica destas em comparação ao FLAIR, com concordâncias entre examinadores clinicamente satisfatórias. A associação significativa entre o número de lesões corticais em PSIR e o grau de incapacidade dos pacientes pode influenciar em decisões terapêuticas.

RESUMO

Objective: Evaluating intra- and inter-observer agreement of the Neer, AO, and AO/OTA proximal humerus fractures classification systems in adults. Methods: In total, 100 X-rays of patients with proximal humerus fractures were selected according to the inclusion and exclusion criteria established in this study. They were evaluated by four evaluators with different levels of expertise. The evaluation was performed at two distinct moments, with an interval of 21 days between each analysis. Images were randomized for the second evaluation by a researcher who did not participate in the image selection process. A Fleiss Kappa test was performed to evaluate intra- and inter-observer agreement. Results: We observed a substantial agreement with k = 0.669, k = 0.715, and k = 0.780 for the Neer, AO, and AO/OTA classification systems, respectively. Conclusion: In the second evaluation, intra-observer agreement improved. In the first evaluation, we obtained values of k = 0.724, k = 0.490, and k = 0.599 for the evaluation of the Neer, AO, and AO/OTA classifications. In the second evaluation, the values k = 0.759, k = 0.772, and k = 0.858. Therefore, the evaluations went from moderate to substantial for the AO classification and from moderate to practically perfect for the AO/OTA classification. The level of inter-observer agreement was substantial (0.61-0.80), with k = 0.669, k = 0.715, and k = 0.780 for the Neer, AO, and AO/OTA classifications, respectively. Level of Evidence III, Cross-Sectional Observational Study.

Objetivo: Avaliar a concordância intra e interobservadores entre os sistemas de classificação Neer, AO e AO/OTA nas fraturas do úmero proximal de indivíduos adultos. Métodos: Após a aplicação dos critérios de inclusão e exclusão determinados para a realização deste trabalho, foram selecionadas 100 radiografias de pacientes com fratura do úmero proximal. Estas foram submetidas à avaliação de quatro examinadores com níveis diferentes de expertise. A avaliação foi realizada em dois momentos distintos, com intervalo de 21 dias entre cada análise. As imagens foram randomizadas para a segunda avaliação por um pesquisador que não participou da seleção de imagens. Foi aplicado o teste kappa de Fleiss para verificar a concordância intra e interobservador. Resultados: Na primeira avaliação obtivemos valores de k = 0,724, k = 0,490 e k = 0,599, enquanto na segunda avaliação, os valores k = 0,759, k = 0,772 e k = 0,858 para as avaliações de Neer, AO e AO/OTA, respectivamente. Isso indica que a concordância intraobservador melhorou na segunda avaliação. Conclusões: As avaliações passaram de moderada para substancial para a classificação AO e de moderada para praticamente perfeita para o sistema AO/OTA. O nível de concordância interobservadores foram considerados substanciais (0,61-0,80) com k = 0,669, k = 0,715 e k = 0,780 para as classificações de Neer, AO e AO/OTA, respectivamente. Nível de Evidência III, Estudo Transversal Observacional.

RESUMO

Unmanned aerial vehicle (UAV) autonomous navigation requires access to translational and rotational positions and velocities. Since there is no single sensor to measure all UAV states, it is necessary to fuse information from multiple sensors. This paper proposes a deterministic estimator to reconstruct the scale factor of the position determined by a simultaneous localization and mapping (SLAM) algorithm onboard a quadrotor UAV. The position scale factor is unknown when the SLAM algorithm relies on the information from a monocular camera. Only onboard sensor measurements can feed the estimator; thus, a deterministic observer is designed to rebuild the quadrotor translational velocity. The estimator and the observer are designed following the immersion and invariance method and use inertial and visual measurements. Lyapunov's arguments prove the asymptotic convergence of observer and estimator errors to zero. The proposed estimator's and observer's performance is validated through numerical simulations using a physics-based simulator.

RESUMO

Introducción: En 2013, desarrollamos una escala, para evaluar resúmenes de congresos de la Sociedad de Cirujanos de Chile (SOCICH). Objetivo: Determinar consistencia interna y confiabilidad interobservador de una escala para evaluar resúmenes de congresos. Material y Método: Estudio de confiabilidad. Doce cirujanos fueron capacitados de forma virtual durante 8 horas, para aplicar la escala. Una vez finalizado el entrenamiento, se les envió un cuestionario para evaluar contenidos de la capacitación, y varios resúmenescasos para ser evaluados con la escala antes señalada. Se aplicó estadística descriptiva, luego se estimó el grado de acuerdo entre observadores para cada ítem de la escala. Posteriormente, se evaluó el coeficiente de correlación (CCI), utilizando un modelo de dos factores mixtos en el que los efectos de los evaluadores son aleatorios y los ítems fijos; utilizando una definición de acuerdo absoluto. Además, se evaluó la consistencia interna de los ítems utilizando alfa de Cronbach, considerando intérvalos de confianza del 95% (IC 95%). Resultados: Luego de analizar las mediciones de los 9 ítems por los 12 observadores, se verificó que el CCI fue de 0,871; con un IC 95% de 0,700; 0,965. El valor de la consistencia interna fue de 0,7 considerando los 9 ítems, no se recomienda eliminar ningún ítem. Conclusión: La escala tiene buena confiabilidad interobservador y los ítems son consistentes entre sí; por lo que puede ser considerada como un instrumento confiable para la valoración de resúmenes de congresos.

Background: In 2013, we developed a scale to evaluate the abstracts of the congresses of the Society of Surgeons of Chile (SOCICH). Objective: To determine internal consistency and interobserver reliability of a scale to evaluate conference abstracts. Material and Methods: Reliability study. Twelve surgeons were trained virtually for 8 hours, to apply the scale. Once the training was finished, they were sent a questionnaire to evaluate the contents of the training, and several summaries-cases to be evaluated with the aforementioned scale. Descriptive statistics were applied, then the degree of agreement between observers was estimated for each item of the scale. Subsequently, intraclass correlation coefficient (ICC) was evaluated, using a mixed two-factor model where the effects of the evaluators are random and the items are fixed, using a definition of absolute agreement. In addition, the internal consistency of the items was evaluated using Cronbach's alpha, considering 95% confidence intervals (95% CI). Results: After analyzing the measurements of the 9 items by the 12 observers, it was verified that the ICC was 0.871; with a 95% CI of 0.700; 0.965. The internal consistency value was 0.7 considering the 9 items, it is not recommended to delete any item. Conclusions: The scale has good internal consistency and interobserver reliability. Therefore, it can be considered as reliable instrument to be used in the evaluation of abstracts for congresses.

Assuntos

RESUMO

The properties of the convergence region of the estimation error of a robust observer for second-order systems are determined, and a new algorithm is proposed for setting the observer parameters, considering persistent but bounded disturbances in the two observation error dynamics. The main contributions over closely related studies of the stability of state observers are: (i) the width of the convergence region of the observer error for the unknown state is expressed in terms of the interaction between the observer parameters and the disturbance terms of the observer error dynamics; (ii) it was found that this width has a minimum point and a vertical asymptote with respect to one of the observer parameters, and their coordinates were determined. In addition, the main advantages of the proposed algorithm over closely related algorithms are: (i) the definition of observer parameters is significantly simpler, as the fulfillment of Riccati equation conditions, solution of LMI constraints, and fulfillment of eigenvalue conditions are not required; (ii) unknown bounded terms are considered in the dynamics of the observer error for the known state. Finally, the algorithm is applied to a model of microalgae culture in a photobioreactor for the estimation of biomass growth rate and substrate uptake rate based on known concentrations of biomass and substrate.

Assuntos

RESUMO

Many systems with distributed dynamics are described by partial differential equations (PDEs). Coupled reaction-diffusion equations are a particular type of these systems. The measurement of the state over the entire spatial domain is usually required for their control. However, it is often impossible to obtain full state information with physical sensors only. For this problem, observers are developed to estimate the state based on boundary measurements. The method presented applies the so-called modulating function method, relying on an orthonormal function basis representation. Auxiliary systems are generated from the original system by applying modulating functions and formulating annihilation conditions. It is extended by a decoupling matrix step. The calculated kernels are utilized for modulating the input and output signals over a receding time window to obtain the coefficients for the basis expansion for the desired state estimation. The developed algorithm and its real-time functionality are verified via simulation of an example system related to the dynamics of chemical tubular reactors and compared to the conventional backstepping observer. The method achieves a successful state reconstruction of the system while mitigating white noise induced by the sensor. Ultimately, the modulating function approach represents a solution for the distributed state estimation problem without solving a PDE online.

Assuntos

RESUMO

Finding objects is essential for almost any daily-life visual task. Saliency models have been useful to predict fixation locations in natural images during a free-exploring task. However, it is still challenging to predict the sequence of fixations during visual search. Bayesian observer models are particularly suited for this task because they represent visual search as an active sampling process. Nevertheless, how they adapt to natural images remains largely unexplored. Here, we propose a unified Bayesian model for visual search guided by saliency maps as prior information. We validated our model with a visual search experiment in natural scenes. We showed that, although state-of-the-art saliency models performed well in predicting the first two fixations in a visual search task ( 90% of the performance achieved by humans), their performance degraded to chance afterward. Therefore, saliency maps alone could model bottom-up first impressions but they were not enough to explain scanpaths when top-down task information was critical. In contrast, our model led to human-like performance and scanpaths as revealed by: first, the agreement between targets found by the model and the humans on a trial-by-trial basis; and second, the scanpath similarity between the model and the humans, that makes the behavior of the model indistinguishable from that of humans. Altogether, the combination of deep neural networks based saliency models for image processing and a Bayesian framework for scanpath integration probes to be a powerful and flexible approach to model human behavior in natural scenarios.