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1.
Ciênc. rural (Online) ; 52(3): e20210213, 2022. tab, graf
Article in English | LILACS-Express | LILACSEXPRESS, LILACS, VETINDEX | ID: biblio-1339661

ABSTRACT

Sunflower produces achenes and oil of good quality, besides serving for production of silage, forage and biodiesel. Growth modeling allows knowing the growth pattern of the crop and optimizing the management. The research characterized the growth of the Rhino sunflower cultivar using the Logistic and Gompertz models and to make considerations regarding management based on critical points. The data used come from three uniformity trials with the Rhino confectionery sunflower cultivar carried out in the experimental area of the Federal University of Santa Maria - Campus Frederico Westphalen in the 2019/2020 agricultural harvest. In the first, second and third trials 14, 12 and 10 weekly height evaluations were performed on 10 plants, respectively. The data were adjusted for the thermal time accumulated. The parameters were estimated by ordinary least square's method using the Gauss-Newton algorithm. The fitting quality of the models to the data was measured by the adjusted coefficient of determination, Akaike information criterion, Bayesian information criterion, and through intrinsic and parametric nonlinearity. The inflection points (IP), maximum acceleration (MAP), maximum deceleration (MDP) and asymptotic deceleration (ADP) were determined. Statistical analyses were performed with Microsoft Office Excel® and R software. The models satisfactorily described the height growth curve of sunflower, providing parameters with practical interpretations. The Logistics model has the best fitting quality, being the most suitable for characterizing the growth curve. The estimated critical points provide important information for crop management. Weeds must be controlled until the MAP. Covered fertilizer applications must be carried out between the MAP and IP range. ADP is an indicator of maturity, after reaching this point, the plants can be harvested for the production of silage without loss of volume and quality.


O girassol produz aquênios e óleo de qualidade, além de servir para produção de silagem, forragem e biodiesel. A modelagem de crescimento permite conhecer o padrão de crescimento da cultura e otimizar o manejo. O objetivo deste trabalho foi caracterizar o crescimento da cultivar de girassol Rhino por meio dos modelos Logístico e Gompertz e fazer considerações a respeito do manejo com base em pontos críticos. Os dados utilizados são oriundos de três ensaios de uniformidade com a cultivar de girassol confeiteiro Rhino, conduzidos na área experimental da Universidade Federal de Santa Maria, Campus Frederico Westphalen, na safra 2019/2020. Foram realizadas 14, 12 e 10 avaliações semanais de altura em 10 plantas, respectivamente, no primeiro, segundo e terceiro ensaio. Os dados foram ajustados em função da soma térmica acumulada. Os parâmetros foram estimados por meio do método dos mínimos quadrados ordinários, usando o algoritmo de Gauss-Newton. A qualidade de ajuste dos modelos aos dados foi medida pelo coeficiente de determinação ajustado, critério de determinação de Akaike, critério bayesiano de informação, e por meio da não linearidade intrínseca e paramétrica. Foram determinados os pontos de inflexão (IP), máxima aceleração (MAP), máxima desaceleração (MDP) e desaceleração assintótica (ADP). As análises estatísticas foram realizadas com Microsoft Office Excel® e o software R. Os modelos descreveram de forma satisfatória a curva de crescimento da altura do girassol, fornecendo parâmetros com interpretações práticas. O modelo Logístico apresenta melhor qualidade de ajuste, sendo o mais adequado para caracterização da curva de crescimento. Os pontos críticos estimados fornecem informações importantes para o manejo da cultura. As plantas daninhas devem ser controladas até o MAP. As aplicações de fertilizantes em cobertura devem ser realizadas entre MAP e IP. O ADP é um indicador de maturidade, após atingir este ponto, as plantas podem ser colhidas para a produção de silagem sem perda de volume e qualidade.


Subject(s)
Nonlinear Dynamics , Helianthus/growth & development
2.
Rev. cuba. inform. méd ; 13(2): e459, 2021. graf
Article in Spanish | LILACS, CUMED | ID: biblio-1357287

ABSTRACT

La Teoría del Caos, considerada la tercera revolución de la física, se ha convertido en un método científico para abordar sistemas complejos que no pueden ser explicados por los recursos tradicionales de la ciencia. Su campo de aplicación es cada vez más amplio, porque el pensamiento complejo ha ofrecido solución a numerosos sistemas en la naturaleza, la biología y muy diversas esferas de la vida. El objetivo de este trabajo es ofrecer una panorámica general sobre el tema, desde una postura no estrictamente matemática. Se realizó una revisión en la literatura y se expone el conocimiento sedimentado en el tiempo, por los estudiosos y expertos en la materia. Se ofrece una visión general de la Teoría del Caos, las condiciones para su surgimiento, así como sus aspectos y propiedades generales expresadas en sus dos dimensiones: tiempo (sistemas dinámicos) y espacio (fractales). Se hacen explícitos en cada caso, los conceptos y definiciones necesarias para entender y hablar de Caos. En un segundo artículo se expondrán las principales aplicaciones de esta teoría en la medicina y en particular en el campo de las neurociencias. Para los profesionales del sector salud, resulta un reto necesario familiarizarse con este nuevo enfoque, entender su esencia, principios y conceptos, para adquirir una cultura del Caos(AU)


Chaos Theory, considered the third revolution in physics, has become a scientific method to address complex systems that cannot be explained by the traditional resources of science. Its field of application is increasingly wide, because complex thinking has offered solutions to numerous systems in nature, biology and very diverse spheres of life. The objective of this work is to offer a general overview of the subject, from a non-strictly mathematical position. A literature review was carried out and the knowledge settled over time, by scholars and experts in the field, is exposed. An overview of Chaos Theory is offered, the conditions for its emergence, as well as its aspects and general properties expressed in its two dimensions: time (dynamic systems) and space (fractals). The concepts and definitions necessary to understand and speak of Chaos are made explicit in each case. In a second article, the main applications of this theory in medicine and in particular in the field of neurosciences will be exposed. For professionals in the health sector, it is a necessary challenge to become familiar with this new approach, understand its essence, principles and concepts, to acquire a culture of Chaos(AU)


Subject(s)
Nonlinear Dynamics
3.
Rev. colomb. cardiol ; 28(2): 136-145, mar.-abr. 2021. tab, graf
Article in Spanish | LILACS, COLNAL | ID: biblio-1341275

ABSTRACT

Resumen Introducción: Los sistemas dinámicos, la entropía y la probabilidad han contribuido de forma significativa al desarrollo de nuevas metodologías que caracterizan al grado de complejidad de la dinámica cardíaca. Objetivo: Confirmar la aplicabilidad clínica de la metodología fundamentada en la teoría de los sistemas dinámicos, la probabilidad y la entropía para evaluar la dinámica cardíaca durante 18 horas. Material y métodos: Se tomaron 570 registros Holter normales en diferentes enfermedades. Para cada uno se construyó un atractor en un mapa de retardo y se evaluó la probabilidad de ocupación de pares ordenados de frecuencias cardíacas durante 18 horas, así como la entropía y sus proporciones. Se compararon las medidas obtenidas con los valores de normalidad y enfermedad establecidos previamente para obtener el diagnóstico matemático de cada Holter. Las conclusiones del Holter se revelaron luego de aplicar la metodología fisicomatemática para calcular sensibilidad, especificidad y coeficiente kappa respecto de la norma de referencia clínica. Resultados: Con las proporciones de la entropía de los atractores se diferenciaron dinámicas cardíacas agudas, crónicas, normales y la evolución entre estos estados con resultados de sensibilidad y especificidad del 100% con una concordancia entre la norma de referencia y el diagnóstico fisicomatemático evaluado con el coeficiente kappa de 1. Conclusiones: Este estudio confirma que la metodología aplicada logra diagnosticar objetivamente la dinámica cardíaca, ya que establece predicciones de estados de normalidad o del nivel de agravamiento de la dinámica, y evidencia la aplicabilidad de esta metodología, lo cual sugiere su potencial uso en el contexto clínico.


Abstract Introduction: Dynamic systems, entropy and probability have contributed significantly in the development of new methodologies that characterize the degree of complexity of cardiac dynamics. Objective: To confirm the clinical applicability of the methodology based on the theory of dynamic systems, probability and entropy to evaluate cardiac dynamics during 18 hours. Material and methods: 570 normal Holter records with different pathologies were taken. For each one an attractor was built on the delay map and the probability of occupation of ordered pairs of heart rates during 18 hours was evaluated, as well as the entropy and its proportions. The measurements obtained were compared with the values of normality and illness established previously to obtain the mathematical diagnosis of each Holter. The conclusions of the Holter were unblinded after having applied the physical-mathematical methodology to calculate sensitivity, specificity and Kappa coefficient with respect to the Gold-Standard. Results: With the proportions of the entropy of the attractors, acute, chronic, normal, and evolution cardiac dynamics were differentiated between these states. the application of the methodology showed a sensitivity and specificity of 100 %. The agreement between the Gold-Standard and the physical-mathematical diagnosis evaluated with the kappa coefficient was 1. Conclusions: This study confirms that the applied methodology manages to objectively diagnose cardiac dynamics, establishing predictions of normality states or the level of aggravation of the dynamics, evidencing the applicability of this methodology, suggesting its potential use in the clinical context.


Subject(s)
Humans , Male , Female , Nonlinear Dynamics , Probability , Electrocardiography, Ambulatory , Heart Rate
4.
Braz. j. med. biol. res ; 54(2): e10084, 2021. tab, graf
Article in English | ColecionaSUS, LILACS, ColecionaSUS | ID: biblio-1142577

ABSTRACT

The objective of this study was to investigate the impact of chronic obstructive pulmonary disease (COPD)-heart failure (HF) coexistence on linear and nonlinear dynamics of heart rate variability (HRV). Forty-one patients (14 with COPD-HF and 27 HF) were enrolled and underwent pulmonary function and echocardiography evaluation to confirm the clinical diagnosis. Heart rate (HR) and R-R intervals (iRR) were collected during active postural maneuver (APM) [supine (10 min) to orthostasis (10 min)], respiratory sinus arrhythmia maneuver (RSA-M) (4 min), and analysis of frequency domain, time domain, and nonlinear HRV. We found expected autonomic response during orthostatic changes with reduction of mean iRR, root mean square of successive differences between heart beats (RMSSD), RR tri index, and high-frequency [HF (nu)] and an increased mean HR, low-frequency [LF (nu)], and LF/HF (nu) compared with supine only in HF patients (P<0.05). Patients with COPD-HF coexistence did not respond to postural change. In addition, in the orthostatic position, higher HF nu and lower LF nu and LF/HF (nu) were observed in COPD-HF compared with HF patients. HF patients showed an opposite response during RSA-M, with increased sympathetic modulation (LF nu) and reduced parasympathetic modulation (HF nu) (P<0.05) compared with COPD-HF patients. COPD-HF directly influenced cardiac autonomic modulation during active postural change and controlled breathing, demonstrating an autonomic imbalance during sympathetic and parasympathetic maneuvers compared with isolated HF.


Subject(s)
Humans , Male , Female , Middle Aged , Aged , Pulmonary Disease, Chronic Obstructive/complications , Heart Failure/complications , Heart Rate , Stroke Volume , Ventricular Function, Left , Nonlinear Dynamics
5.
Article in Chinese | WPRIM | ID: wpr-879283

ABSTRACT

The use of non-invasive blood glucose detection techniques can help diabetic patients to alleviate the pain of intrusive detection, reduce the cost of detection, and achieve real-time monitoring and effective control of blood glucose. Given the existing limitations of the minimally invasive or invasive blood glucose detection methods, such as low detection accuracy, high cost and complex operation, and the laser source's wavelength and cost, this paper, based on the non-invasive blood glucose detector developed by the research group, designs a non-invasive blood glucose detection method. It is founded on dual-wavelength near-infrared light diffuse reflection by using the 1 550 nm near-infrared light as measuring light to collect blood glucose information and the 1 310 nm near-infrared light as reference light to remove the effects of water molecules in the blood. Fourteen volunteers were recruited for


Subject(s)
Blood Glucose , Diabetes Mellitus , Humans , Nonlinear Dynamics
6.
Article in English | WPRIM | ID: wpr-922203

ABSTRACT

BACKGROUND@#For the reason that many studies have been inconclusive on the effect of humidity on respiratory disease, we examined the association between absolute humidity and respiratory disease mortality and quantified the mortality burden due to non-optimal absolute humidity in Guangzhou, China.@*METHODS@#Daily respiratory disease mortality including total 42,440 deaths from 1 February 2013 to 31 December 2018 and meteorological data of the same period in Guangzhou City were collected. The distributed lag non-linear model was used to determine the optimal absolute humidity of death and discuss their non-linear lagged effects. Attributable fraction and population attributable mortality were calculated based on the optimal absolute humidity, defined as the minimum mortality absolute humidity.@*RESULTS@#The association between absolute humidity and total respiratory disease mortality showed an M-shaped non-linear curve. In total, 21.57% (95% CI 14.20 ~ 27.75%) of respiratory disease mortality (9154 deaths) was attributable to non-optimum absolute humidity. The attributable fractions due to high absolute humidity were 13.49% (95% CI 9.56 ~ 16.98%), while mortality burden of low absolute humidity were 8.08% (95% CI 0.89 ~ 13.93%), respectively. Extreme dry and moist absolute humidity accounted for total respiratory disease mortality fraction of 0.87% (95% CI - 0.09 ~ 1.58%) and 0.91% (95% CI 0.25 ~ 1.39%), respectively. There was no significant gender and age difference in the burden of attributable risk due to absolute humidity.@*CONCLUSIONS@#Our study showed that both high and low absolute humidity are responsible for considerable respiratory disease mortality burden, the component attributed to the high absolute humidity effect is greater. Our results may have important implications for the development of public health measures to reduce respiratory disease mortality.


Subject(s)
China/epidemiology , Cities/epidemiology , Climate , Humans , Humidity/adverse effects , Models, Theoretical , Nonlinear Dynamics , Respiratory Tract Diseases/mortality , Sensitivity and Specificity
7.
Article in Chinese | WPRIM | ID: wpr-921531

ABSTRACT

Objective To evaluate the influence of temperature on the outpatient visits for urticaria in Lanzhou City and its hysteresis and to find out the sensitive populations by sex and age stratification.Methods We collected the urticaria outpatient data in three grade A class three hospitals as well as the meteorological data and air pollutant data in Lanzhou from January 2011 to December 2017.The distributed lag non-linear model(DLNM)was employed to analyze the influence of daily mean temperature on the outpatient visits for urticaria.Stratification analysis was performed for different age groups(0-14,15-59,≥60 years)and different sex populations.Results Temperature had a non-linear relationship with the outpatient visits for urticaria,and there existed hysteresis.During the research period,the average daily outpatient visits for urticaria at the three hospitals in Lanzhou was 25,ranging from 1 to 76.With the rise in the daily mean temperature within 0-10 ℃,the risk of outpatient visits for urticaria first increased and then decreased.When the daily mean temperature was 2 ℃,hysteresis occurred on the 18th day,and the relative risk(


Subject(s)
Adolescent , Air Pollutants/analysis , Child , Child, Preschool , China/epidemiology , Female , Humans , Infant , Infant, Newborn , Middle Aged , Nonlinear Dynamics , Outpatients , Temperature , Urticaria/epidemiology
8.
Article in English | LILACS, BDENF | ID: biblio-1280469

ABSTRACT

Objective: to carry out a theoretical reflection on the Nursing Now Campaign and the experience of the unexpected irruptions facing the pandemic period. Method: a theoretical-reflective study, supported by the theoretical framework of complexity thinking. It aims at understanding the dialogic between the notions of order, disorder and organization, which translate the transition from simplification to complexity of the pandemic phenomenon and its relation to the theme of Nursing Now and Nursing in the future. Results: the universe of phenomena is simultaneously composed of order, disorder and organization. Reasserting the central role of Nursing in the health team, facing the irruptions and uncertainties caused by the current pandemic, implies the ability to dialog with disorder and raise a new and more complex global (re)organization of the being and doing Nursing. Conclusion: in addition to answers, theoretical reflection raises new questions and irruptions. The inseparability between the notions of order and disorder in the evolutionary dynamics of the Nursing system is conceived and the promotion of even more complex levels of organization, management and Nursing assistance to achieve universal access to health is advocated.


Objetivo: realizar reflexão teórica acerca da Campanha Nursing Now e a experiência das irrupções do inesperado face ao período pandêmico. Método: estudo teórico-reflexivo, apoiado no referencial teórico do pensamento da complexidade. Visa-se à compreensão da dialógica entre as noções de ordem, de desordem e de organização, as quais traduzem a passagem da simplificação à complexidade do fenômeno da pandemia e sua relação com a temática Nursing Now and Nursing in the future. Resultados: o universo dos fenômenos é tecido, simultaneamente, de ordem, de desordem e de organização. Reafirmar o papel central da Enfermagem na equipe de saúde, face às irrupções e incertezas provocadas pela pandemia em curso, implica capacidade de dialogar com a desordem e suscitar uma nova e mais complexa (re)organização global do ser e do fazer Enfermagem. Conclusão: a reflexão teórica suscita, além de respostas, novos questionamentos e novas irrupções. Concebe-se a inseparabilidade entre as noções de ordem e de desordem na dinâmica evolutiva do sistema de Enfermagem e defende-se a promoção de níveis de organização, gestão e assistência de Enfermagem ainda mais complexos para o alcance do acesso universal à saúde.


Objetivo: realizar una reflexión teórica sobre la Campaña Nursing Now y la experiencia de las irrupciones de lo inesperado ante el período pandémico. Método: estudio teórico-reflexivo, basado en el marco teórico del pensamiento complejo. Tiene como objetivo comprender la dialógica entre las nociones de orden, desorden y organización, que traducen la transición de la simplificación a la complejidad del fenómeno pandémico y su relación con el tema Nursing Now and Nursing in the future. Resultados: el universo de los fenómenos se entreteje, simultáneamente, de orden, desorden y organización. Reafirmar el papel central de la Enfermería en el equipo de salud, ante las irrupciones e incertidumbres provocadas por la pandemia actual, implica la capacidad de dialogar con el desorden y propiciar una nueva y más compleja (re)organización global del ser y hacer Enfermería. Conclusión: la reflexión teórica plantea, además de respuestas, nuevas interrogantes y nuevas irrupciones. Se concibe la inseparabilidad entre las nociones de orden y desorden en la dinámica evolutiva del sistema de Enfermería y se aboga por la promoción de niveles aún más complejos de organización, gestión y asistencia de Enfermería para lograr el acceso universal a la salud.


Subject(s)
Nursing , Nonlinear Dynamics , Coronavirus , Pandemics , Nursing Care
9.
Rev. Fac. Med. (Bogotá) ; 68(4): 577-585, oct.-dic. 2020. tab, graf
Article in Spanish | LILACS, COLNAL | ID: biblio-1149559

ABSTRACT

Resumen Introducción. La actividad cerebral, teniendo en cuenta su dinámica aperiódica, puede ser estudiada mediante funciones no lineales o sistemas caóticos. Objetivo. Estudiar las diferencias inter e intra-hemisféricas de la relación orden/caos en la actividad cerebral de la onda beta en estudiantes universitarios durante la resolución de un test de atención. Materiales y métodos. La muestra estuvo compuesta por 10 estudiantes universitarios de educación física, todos hombres, a quienes se les aplicó la prueba de atención de Toulouse-Piéron para registrar, mediante electroencefalograma, su actividad cerebral por 8 minutos durante la ejecución de la prueba. Para el registro de la actividad cerebral se usó el dispositivo Emotiv Epoc®. Resultados. Se observaron diferencias intra e inter-hemisfericas en la relación orden/caos entre los participantes en las regiones prefrontales, temporales y occipitales (p<0.05), así como diversas correlaciones entre estas regiones (r>0.600), las cuales variaron tanto entre los sujetos, como a nivel individual a medida que avanzaba la ejecución de la prueba. Conclusión. A medida que la ejecución de la prueba avanzaba, las asimetrías hemisféricas aumentaban, por lo que es posible concluir que la participación en procesos cognitivos continuos produce diferencias en la actividad cerebral; sin embargo, es necesario realizar estudios similares en muestras con diferentes características (diversos grupos etarios, mujeres, etc.) y donde se apliquen otras pruebas de atención para poder confirmar o contrastar los resultados aquí reportados.


Abstract Introduction: Considering its aperiodic dynamics, brain activity can be studied by means of non-linear functions or chaotic systems. Objective: To analyze the inter- and intra-hemispheric differences of the order/chaos relationship observed in the beta waves of university students during their participation in an attention test. Materials and methods: The sample was composed of 10 university physical education students, all males, who were administered the Toulouse-Piéron Concentrated Attention Test to record, by means of electroencephalogram, their brain activity for 8 minutes during the execution of the test. The Emotiv Epoc® device was used to record brain activity. Results: Intra- and inter-hemispheric differences were observed in the order/chaos relationship among the participants in the prefrontal, temporal and occipital regions (p<0.05), as well as various correlations between these regions (r>0.600), which varied both between participants and individually as the execution of the test progressed. Conclusion: As the test progressed, hemispheric asymmetries increased, which allows concluding that engaging in continuous cognitive processes causes brain activity differences. However, it is necessary to carry out similar studies in samples with different characteristics (different age groups, women, etc.) in which other attention tests are used to confirm or contrast the results reported here.


Subject(s)
Humans , Electroencephalography , Attention , Nonlinear Dynamics
10.
Arq. bras. med. vet. zootec. (Online) ; 72(5): 1778-1788, Sept.-Oct. 2020. tab, graf
Article in English | LILACS, VETINDEX | ID: biblio-1131564

ABSTRACT

Length growth as a function of time has a non-linear relationship, so nonlinear equations are recommended to represent this kind of curve. We used six nonlinear models to calculate the length gain of rainbow trout (Oncorhynchus mykiss) during the final grow-out phase of 98 days under three different feed types in triplicate groups. We fitted the von Bertalanffy, Gompertz, Logistic, Brody, Power Function, and Exponential equations to individual length-at-age data of 900 fish. Equations were fitted to the data based on the least square method using the Marquardt iterative algorithm. Accuracy of the fitted models was evaluated using a model performance metrics combining mean squared residuals (MSR), mean absolute error (MAE) and Akaike's Information Criterion corrected for small sample sizes (AICc). All models converged in all cases tested. Evaluation criteria for the Logistic model indicated the best overall fit (0.67 of combined metric MSR, MAE and AICc) under all different feeding types, followed by the Exponential model (0.185), and the von Bertalanffy and Brody model (0.074, respectively). Additionally, ∆AICc results identify the Logistic and Gompertz models as being substantially supported by the data in 100% of cases. The logistic model can be suggested for length growth prediction in aquaculture of rainbow trout.(AU)


O crescimento em comprimento em função do tempo tem uma relação não linear; por isso, funções não lineares são recomendáveis para descrever essa relação. Seis modelos não lineares foram usados para calcular o ganho em comprimento de truta-arco-íris (Oncorhynchus mykiss) durante 98 dias, na fase final da engorda, submetidas a três dietas diferentes em grupos triplicados. Foram ajustadas as equações de von Bertalanffy, Gompertz, logístico, Brody, função potencial e exponencial a dados individuais de comprimento-idade de 900 peixes. O ajuste foi feito pelo método dos mínimos quadrados, usando-se o algoritmo iterativo de Marquardt. A precisão do ajuste foi avaliada pelo uso de critérios combinados de ajuste: quadrado médio do resíduo (QMR), erro médio absoluto (EMA) e o critério de informação de Akaike corrigido para tamanhos amostrais pequenos (AICc). Todos os modelos atingiram a convergência para cada caso avaliado. Os critérios de avaliação do modelo logístico indicaram o melhor ajuste geral (0,67 vez dos critérios combinados MSR, MAE e AICc) para cada grupo de peixe avaliado, seguido pelo modelo exponencial (0,185) e os modelos von Bertalanffy e Brody, com 0,074, respectivamente. Similarmente, os resultados de ΔAICc identificaram-se ao modelo logístico e ao de Gompertz, com grande suporte das informações em 100% dos casos. Por fim, o modelo logístico pode ser sugerido na predição do crescimento em comprimento de truta-arco-íris cultivada.(AU)


Subject(s)
Animals , Oncorhynchus mykiss/growth & development , Nonlinear Dynamics , Aquaculture/methods , Logistic Models
11.
Rev. cuba. invest. bioméd ; 39(3): e626, jul.-set. 2020. tab, graf
Article in Spanish | LILACS, CUMED | ID: biblio-1138932

ABSTRACT

Introducción: El electroencefalograma permite registrar la actividad eléctrica cerebral en estado de reposo y durante la ejecución de tareas cognitivas. Objetivo: Evaluar si la actividad cerebral, analizada como dinámica no lineal, se mantiene estable durante diferentes ventanas temporales en una condición basal con ojos cerrados. Métodos: Se realizaron registros con electroencefalograma durante dos minutos a 14 estudiantes universitarios varones. Posteriormente, se compararon las medias de índices de Hurst (H) en ventanas temporales de 60, 30 y 10 segundos. Resultados: Las medias de los índices H son estables a través de diferentes ventanas temporales en las regiones prefrontales, temporales y occipitales. Conclusiones: Los registros de electroencefalograma en condiciones basales con los ojos cerrados son válidos para comparar protocolos experimentales de resolución de problemas cognitivos utilizando el exponente de Hurst en los sujetos de la muestra y en otros con características similares(AU)


Introduction: Electroencephalography makes it possible to record brain electrical activity at rest and during the performance of cognitive tasks. Objective: Determine whether brain activity analyzed as nonlinear dynamics remains stable during various time windows in basal, eyes closed conditions. Methods: Electroencephalographic records of 14 male university students were taken during two minutes. Hurst's index means (H) were then compared in time windows of 60, 30 and 10 seconds. Results: H index means are stable throughout the various time windows in the prefrontal, temporal and occipital regions. Conclusions: Electroencephalographic records in basal, eyes closed conditions are valid to compare experimental protocols for cognitive problem solving using the Hurst exponent in subjects from the sample as well as others of similar characteristics(AU)


Subject(s)
Humans , Male , Young Adult , Rest , Electroencephalography , Students , Nonlinear Dynamics
12.
Dental press j. orthod. (Impr.) ; 25(4): 44-50, July-Aug. 2020. tab, graf
Article in English | LILACS, BBO | ID: biblio-1133679

ABSTRACT

ABSTRACT Objective: To perform a numerical simulation using FEM to study the von Mises stresses on Mushroom archwires. Methods: Mushroom archwires made of titanium-molybdenum alloy with 0.017 x 0.025-in cross-section were used in this study. A YS of 1240 MPa and a Young's modulus of 69 GPa were adopted. The archwire was modeled in Autodesk Inventor software and its behavior was simulated using the finite element code Ansys Workbench (Swanson Analysis Systems, Houston, Pennsylvania, USA). A large displacement simulation was used for non-linear analysis. The archwires were deformed in their extremities with 0° and 45°, and activated by their vertical extremities separated at 4.0 or 5.0 mm. Results: Tensions revealed a maximum of 1158 MPa at the whole part of the loop at 5.0mm of activation, except in a very small area situated at the top of the loop, in which a maximum of 1324 Mpa was found. Conclusions: Mushroom loops are capable to produce tension levels in an elastic range and could be safely activated up to 5.0mm.


RESUMO Objetivo: Realizar uma simulação numérica, por meio do Método dos Elementos Finitos (MEF), para obter as tensões de von Mises em arcos Mushroom. Métodos: Foram usados arcos com geometria Mushroom de titânio-molibdênio, com secção transversal 0,017" x 0,025". Adotou-se valores de tensão de escoamento (σesc) de 1.240 MPa e módulo de elasticidade (E) de 69 GPa. O arco foi modelado por meio do software Autodesk Inventor, e seu desempenho foi simulado utilizando-se o software de elementos finitos Ansys Workbench (Swanson Analysis System, Houston, Pennsylvania, EUA). Para a simulação, foi considerada a análise para grandes deslocamentos. O arco foi conformado em suas extremidades considerando-se planos de 0° e 45°, pré-ativado em 2,5mm e ativado por meio de suas extremidades verticais, separadas 4,0 mm ou 5,0 mm. Resultados: As tensões revelaram um valor máximo de 1.158 MPa na maior parte da alça, aos 5,0 mm de ativação, com exceção de uma área muito pequena, com valor de 1.324 MPa, situada no topo da alça. Conclusões: Os arcos Mushroom são capazes de produzir níveis de tensão situados dentro da região elástica e poderiam ser ativados com segurança até os 5,0 mm de ativação.


Subject(s)
Titanium , Finite Element Analysis , Molybdenum , Nonlinear Dynamics
13.
Rev. salud pública ; 22(2): e387373, mar.-abr. 2020. tab, graf
Article in Spanish | LILACS | ID: biblio-1115878

ABSTRACT

RESUMEN Objetivo El trabajo tiene como objetivo analizar la dinámica del comportamiento de la COVID-19 en el Perú, estimar y evaluar el impacto de la política pública de supresión (cuarentena). Métodos El modelo epidemiológico SIR y la estimación con el método de Mínimos Cuadrados Ordinarios (MCO). Resultados Se encontró que el número básico de propagación (Ro) cayó de 6,0 a 3,2 habiéndose reducido en 54% por efecto de la estrategia de supresión, y dos meses después cayó a 1,7. Sin embargo, sigue siendo alto y evidencia que aún continúa en expansión el nivel de infectados, con los efectos sociales y económicos adversos que esta medida implica. Conclusión La COVID-19 es una enfermedad que crece exponencialmente, por lo cual, la política de salud basada en la estrategia de supresión ha permitido aplanar la curva de contagio, evitando el colapso del Sistema de Salud.(AU)


ABSTRACT Objective The objective of the study is to analyze the behavior dynamics of COVID-19 in Peru, estimate and evaluate the impact of the suppression public policy (quarantine). Methods The SIR epidemiological model and the estimation with the ordinary Least Squares (OLS) method. Results It was found that the basic number of propagation (Ro) fell from 6,0 to 3,2 having been reduced by 54% due to the suppression strategy; and two months later it falls to 1,7. However, it remains high and evidence that the level of those infected continues to expand with its adverse social and economic effects. Conclusion: COVID-19 is a disease that grows exponentially, and that the health policy based on the suppression strategy has allowed to flatten the contagion curve, thus avoiding the collapse of the Health System.(AU)


Subject(s)
Humans , Public Policy , Health Care Economics and Organizations , Quarantine/organization & administration , Coronavirus Infections/epidemiology , Peru/epidemiology , Health Profile , Nonlinear Dynamics
14.
Rev. cuba. inform. méd ; 11(2)jul.-dic. 2019. tab, graf
Article in English | LILACS, CUMED | ID: biblio-1093315

ABSTRACT

Background: Age-related changes in the vascular network have been widely documented, however, nonlinear identification has been poorly applied to the analysis of cardiovascular signals. Objective: To determine the impact of age on spectral components of Noise-free realizations (NFR) obtained from photoplethysmographic signals, summarized in the Kernel Complexity Regressive Index (KCRIndex). Methods: With 190 apparently healthy participants (9 to 89 years) from Orense, Spain, Photoplethysmographic signals were recorded during 5 minutes in supine position using Nellcor-395 pulse oximeter; signals were digitized at 1000 Hz, and furtherly submitted to nonlinear identification via a kernel nonlinear autoregressive estimator. KCRIndex is defined as the average of at least three negative slope values at the NFR log-log spectrum in the 9 to 25 Hz frequency region. Results: KCRIndex decreased with age in a linear fashion and did not differ between genders. The regression line obtained was KCRIndex=-0.025*age+6.868 (r=-0.751). Conclusions: KCRIndex, is strongly correlated with age, thus opening up new possibilities for cardiovascular exploration at primary health care settings and even on open field conditions(AU)


Antecedentes: los cambios relacionados con la edad en la red vascular se han documentado ampliamente, sin embargo, la identificación no lineal solo se ha aplicado de manera esporádica al análisis de las señales cardiovasculares. Objetivo: determinar los cambios con la edad en los componentes espectrales de las realizaciones sin ruido (NFR) obtenidas a partir de señales fotopletismográficas, resumidas en el índice regresivo de la complejidad por núcleos (KCRIndex). Métodos: Con 190 participantes aparentemente sanos (de 9 a 89 años) residentes en Orense, España, se registraron señales fotopletismográficas durante 5 minutos en posición supina usando un oxímetro de pulso Nellcor-395; las señales se digitalizaron a 1000 Hz, y se sometieron a identificación no lineal a través de un estimador autorregresivo no lineal por núcleos. El KCRIndex se define como el promedio de al menos tres valores de pendiente negativos en el espectro log-log de NFR en la región de frecuencia de 9 a 25 Hz. Resultados: KCRIndex disminuyó con la edad de forma lineal y no difirió entre géneros. La línea de regresión obtenida fue KCRIndex = -0.025 * edad + 6.868 (r = -0.751). Conclusiones: Este índice propuesto está fuertemente correlacionado con la edad, lo que abre nuevas posibilidades para la exploración cardiovascular en entornos de atención primaria de salud e incluso en condiciones de campo(AU)


Subject(s)
Photoplethysmography/methods , Nonlinear Dynamics , Age Distribution , Statistics, Nonparametric
15.
Rev. bras. cir. cardiovasc ; 34(5): 572-580, Sept.-Oct. 2019. tab, graf
Article in English | LILACS | ID: biblio-1042041

ABSTRACT

Abstract Objective: To characterize the behavior of cardiac autonomic modulation in individuals with different times after orthotopic heart transplantation (HTx) using symbolic dynamics analysis. Methods: Sixty patients were evaluated after HTx. We recorded their instantaneous R-R intervals (RRi) by cardiac monitor Polar® RS800CX™ (Polar Electro Oy, Kempele, Finland) for 10 minutes. The same sequence of RRi with 256 consecutive beats was used to perform spectral analysis and symbolic dynamics analysis. We used hierarchical clustering to form groups. One-way analysis of variance (ANOVA) (with Holm-Sidak method) or one-way Kruskal-Wallis test (with Dunn´s post-hoc test) was used to analyze the difference between groups. Linear correlation analysis between variables was performed using Pearson's or Spearman's tests. P-value < 0.05 was considered statistically significant. Results: The 0V% index increased, the 2UV% index and the normalized complexity index decreased with an increase of HTx postoperative time. There were a negative correlation between complexity indexes and 0V% and a positive correlation between complexity indexes and 2UV%. Conclusion: Symbolic dynamics indexes were able to show a specific cardiac autonomic modulation pattern for HTx recipients with different postoperative times.


Subject(s)
Humans , Male , Female , Adult , Middle Aged , Parasympathetic Nervous System/physiopathology , Sympathetic Nervous System/physiopathology , Heart Transplantation/rehabilitation , Nonlinear Dynamics , Heart/physiopathology , Postoperative Period , Reference Values , Time Factors , Linear Models , Cross-Sectional Studies , Retrospective Studies , Analysis of Variance , Statistics, Nonparametric , Entropy , Heart Rate/physiology
17.
Prensa méd. argent ; 105(3): 110-118, may 2019. tab, fig
Article in Spanish | LILACS, BINACIS | ID: biblio-1025204

ABSTRACT

Objetivo: Desarrollar una nueva metodología física y matemática para diagnosticar la dinámica cardíaca caótica fetal a partir de atractores de la frecuencia cardíaca. Metodología: Se realizó una inducción matemática con tres trazados de monitorias fetales; una reactiva sin dudas en su evaluación, una plana y una con pérdida aguda de bienestar fetal, para cada una de ellas se generó un atractor caótico a partir de las frecuencias cardíacas, se evaluaron los espacios de ocupación de cada atractor en dos rejillas, y se establacieron diferencias matemáticas entre trazados de monitorias reactivas y no reactivas. Posteriormente se analizaron otros 15 trazados de monitorias fetales, para refinar los parámetros diagnósticos. Resultados: Los espacios evaluados para los atractores de monitorias normales presentaron valores entre 53 y 117 para la rejilla más pequeña; mientras que las monitorias anormales presentaron valores menores a 41 y mayores a 123. Conclusiones: se desarrolló una nueva metodología de ayuda diagnóstica para evaluar la dinámica cardíaca caótica fetal, que diferencia normalidad de enfermedad de forma objetiva y reproducible (AU)


Objective: To develop a new physical and mathematical methodology to diagnose fetal chaotic cardiac dynamics from heart rate attractors. Methods: A mathematical induction was performed with three fetal monitoring tracings;one of them, reactive without doubt in its evaluation, other plane and other with acute loss of fetal well-being, for each of them a chaotic attractor was generated from the cardiac frequencies, the spaces of occupation of each attractor in two grids were evaluated, and mathematical differences were established between reactive and non-reactive monitorin tracings. A further 15 fetal monitoring tracings were then analyzed to refine the diagnostic parameters. Results: The spaces evaluated for the normal monitor attractors presented values between 53 and 177 for the smallest grid; while abnormal monitoring had values lower than 41 and greater than 12.3. conclusions: a new methodology of diagnostic aid was developed to evaluate fetal chaotic cardiac dynamics, which distinguishes normality of disease in an objective and reproductible way (AU)


Subject(s)
Humans , Female , Pregnancy , Prenatal Diagnosis , Nonlinear Dynamics , Fractals , Methodology , Fetal Monitoring
18.
Article in Korean | WPRIM | ID: wpr-764688

ABSTRACT

PURPOSE: This study used a system dynamics methodology to identify correlation and nonlinear feedback structures among factors affecting adolescent cyberbullying victims (CV) in Korea and to construct and verify a simulation model. METHODS: Factors affecting CV were identified by reviewing a theoretical background in existing literature and referencing various statistical data. Related variables were identified through content validity verification by an expert group, after which a causal loop diagram (CLD) was constructed based on the variables. A stock-flow diagram (SFD) using Vensim Professional 7.3 was used to establish a CV model. RESULTS: Based on the literature review and expert verification, 22 variables associated with CV were identified and the CLD was prepared. Next, a model was developed by converting the CLD to an SFD. The simulation results showed that the variables such as negative emotions, stress levels, high levels of conflict in schools, parental monitoring, and time spent using new media had the strongest effects on CV. The model's validity was verified using equation check, sensitivity analysis for time-step and simulation with 4 CV adolescent. CONCLUSION: The system dynamics model constructed in this study can be used to develop intervention strategies in schools that are focused on counseling that can prevent cyberbullying and assist in the victims' recovery by formulating a feedback structure and capturing the dynamic changes observed in CV. To prevent cyberbullying, it is necessary to develop more effective strategies such as prevention education, counseling and treatment that considers factors pertaining to the individual, family, school, and media.


Subject(s)
Adolescent , Bullying , Counseling , Education , Humans , Korea , Nonlinear Dynamics , Parents
19.
Article in English | WPRIM | ID: wpr-763689

ABSTRACT

Mitochondrial function is crucial for the maintenance of cellular homeostasis under physiological and stress conditions. Thus, chronic exposure to environmental chemicals that affect mitochondrial function can have harmful effects on humans. We argue that the concept of hormesis should be revisited to explain the non-linear responses to mitochondrial toxins at a low-dose range and develop practical methods to protect humans from the negative effects of mitochondrial toxins. Of the most concern to humans are lipophilic chemical mixtures and heavy metals, owing to their physical properties. Even though these chemicals tend to demonstrate no safe level in humans, a non-linear dose-response has been also observed. Stress response activation, i.e., hormesis, can explain this non-linearity. Recently, hormesis has reemerged as a unifying concept because diverse stressors can induce similar stress responses. Besides potentially harmful environmental chemicals, healthy lifestyle interventions such as exercise, calorie restriction (especially glucose), cognitive stimulation, and phytochemical intake also activate stress responses. This conceptual link can lead to the development of practical methods that counterbalance the harm of mitochondrial toxins. Unlike chemical hormesis with its safety issues, the activation of stress responses via lifestyle modification can be safely used to combat the negative effects of mitochondrial toxins.


Subject(s)
Dementia , Diabetes Mellitus, Type 2 , Environmental Exposure , Environmental Pollutants , Homeostasis , Hormesis , Humans , Life Style , Metals, Heavy , Mitochondria , Nonlinear Dynamics , Organic Chemicals
20.
Prensa méd. argent ; 104(7): 352-360, sep2018. tab, graf
Article in Spanish | LILACS, BINACIS | ID: biblio-1051025

ABSTRACT

Antecedentes: Con conceptos provenientes de la teoría de sistemas dinámicos y la geometría fractal, se ha logrado caracterizar el comportamiento de la dinámica cardíaca, dando resultados objetivos y estableciendo distinciones entre estados de normalidad y enfermedad. Objetivo: Aplicar una ley matemática exponencial de la dinámica cardíaca, inscrita en el contexto de los sistemas dinámicos y la geometría fractal, para evidenciar su utilidad diagnóstica en 16 horas. Materiales y métodos: Fueron empleados 200 Holters y registros electrocardiográficos continuos, entre normales y con diferentes alteraciones cardíacas. Se simuló una secuencia de frecuencias cardíacas en 16 y 21 horas, con la cual se construyó el atractor de cada dinámica. También se calculó la dimensión fractal y la ocupación de los atractores en el espacio fractal. Se estableció el diagnóstico físico-matemático en 16 y 21 horas y la subsecuente validación estadística. Resultados: Fueron obtenidos valores en la rejilla Kp entre 44 y 198 para estados patológicos y entre 221 y 377 para estados de normalidad en 16 horas, la sensibilidad y especificidad fue del 100% y el coeficiente Kappa de 1. Conclusión: Se logró diferenciar de manera adecuada estados normales de patológicos mediante la ley exponencial aplicada en registros de 16 horas


Background: With concepts derived from dynamical systems theory and fractal geometry, it has been possible to characterize the behavior of the cardiac dynamics, giving objective results and estabishing distinctions between states of normality and disease. Objective: To apply an exponential mathematical law of cardiac dynamics, inscribed in the context of dynamical systems and fractal geometry, to demonstrate its diagnostic utility in the context of a reduction in the evaluation time, originally of 21 hours. Materials and methods: There were used 200 Holters and cotinuous electrocardiographic records, between normal and with different cardiac alterations. A sequence of heart rates was simulated in 16 and 21 hours, with which the attractor of each dynamic was constructed. There were also calculated the fractal dimension and the occupation of the attractors in the fractal space. The physical-mathematical diagnosis was establishd at 16 and 21 hours, and the staqtistical validation was performed. Results: Values obtained in the Kp grid were between 44 y 198 for pathological sttes, and between 221 and 377 for normal states in 16 hours. The sensitivity and specificity was 100% and the Kappa coefficient was 1. Conclusion: It was possible to differentiate adequately normal states of pathological by means fo the exponential law applied in registers of 16 hours


Subject(s)
Humans , Adult , Middle Aged , Aged , Aged, 80 and over , Statistical Analysis , Electrocardiography, Ambulatory/statistics & numerical data , Nonlinear Dynamics , Fractals , Heart Rate Determination/methods , Heart Rate , Reference Standards
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