Flexible Force Sensor Based on a PVA/AgNWs Nanocomposite and Cellulose Acetate.

Nanocomposites are materials of special interest for the development of flexible electronic, optical, and mechanical devices in applications such as transparent conductive electrodes and flexible electronic sensors. These materials take advantage of the electrical, chemical, and mechanical properties of a polymeric matrix, especially in force sensors, as well as the properties of a conductive filler such as silver nanowires (AgNWs). In this work, the fabrication of a force sensor using AgNWs synthesized via the polyol chemical technique is presented. The nanowires were deposited via drop-casting in polyvinyl alcohol (PVA) to form the active (electrode) and resistive (nanocomposite) sensor films, with both films separated by a cellulose acetate substrate. The dimensions of the resulting sensor are 35 mm × 40 mm × 0.1 mm. The sensor shows an applied force ranging from 0 to 3.92 N, with a sensitivity of 0.039 N. The sensor stand-off resistance, exceeding 50 MΩ, indicates a good ability to detect changes in applied force without an external force. Additionally, studies revealed a response time of 10 ms, stabilization of 9 s, and a degree of hysteresis of 1.9%. The voltage response of the sensor under flexion at an angle of 85° was measured, demonstrating its functionality over a prolonged period. The fabricated sensor can be used in applications that require measuring pressure on irregular surfaces or systems with limited space, such as for estimating movement in robot joints.

Inhalable porous particles as dual micro-nano carriers demonstrating efficient lung drug delivery for treatment of tuberculosis.

Inhalation therapy treating severe infectious disease is among the more complex and emerging topics in controlled drug release. Micron-sized carriers are needed to deposit drugs into the lower airways, while nano-sized carriers are of preference for cell targeting. Here, we present a novel and versatile strategy using micron-sized spherical particles with an excellent aerodynamic profile that dissolve in the lung fluid to ultimately generate nanoparticles enabling to enhance both extra- and intra-cellular drug delivery (i.e., dual micro-nano inhalation strategy). The spherical particles are synthesised through the condensation of nano-sized amorphous silicon dioxide resulting in high surface area, disordered mesoporous silica particles (MSPs) with monodispersed size of 2.43 µm. Clofazimine (CLZ), a drug shown to be effective against multidrug-resistant tuberculosis, was encapsulated in the MSPs obtaining a dry powder formulation with high respirable fraction (F.P.F. <5 µm of 50%) without the need of additional excipients. DSC, XRPD, and Nitrogen adsorption-desorption indicate that the drug was fully amorphous when confined in the nano-sized pores (9-10 nm) of the MSPs (shelf-life of 20 months at 4 °C). Once deposited in the lung, the CLZ-MSPs exhibited a dual action. Firstly, the nanoconfinement within the MSPs enabled a drastic dissolution enhancement of CLZ in simulated lung fluid (i.e., 16-fold higher than the free drug), increasing mycobacterial killing than CLZ alone (p = 0.0262) and reaching concentrations above the minimum bactericidal concentration (MBC) against biofilms of M. tuberculosis (i.e., targeting extracellular bacteria). The released CLZ permeated but was highly retained in a Calu-3 respiratory epithelium model, suggesting a high local drug concentration within the lung tissue minimizing risk for systemic side effects. Secondly, the micron-sized drug carriers spontaneously dissolve in simulated lung fluid into nano-sized drug carriers (shown by Nano-FTIR), delivering high CLZ cargo inside macrophages and drastically decreasing the mycobacterial burden inside macrophages (i.e., targeting intracellular bacteria). Safety studies showed neither measurable toxicity on macrophages nor Calu-3 cells, nor impaired epithelial integrity. The dissolved MSPs also did not show haemolytic effect on human erythrocytes. In a nutshell, this study presents a low-cost, stable and non-invasive dried powder formulation based on a dual micro-nano carrier to efficiently deliver drug to the lungs overcoming technological and practical challenges for global healthcare.

Quantification of hCG Hormone Using Tapered Optical Fiber Decorated with Gold Nanoparticles.

In this study, a novel technique for the quantification of the human chorionic gonadotropin (hCG) hormone using localized surface plasmons and a tapered optical fiber decorated with gold nanoparticles (Au-NPs) is reported. The tapered optical fiber fabrication process involves stretching a single-mode optical fiber using the flame-brushing system. The waist of the tapered optical fiber reaches a diameter of 3 µm. Decoration of the taper is achieved through the photodeposition of 100 nm Au-NPs using the drop-casting technique and a radiation source emitting at 1550 nm. The presence of the hCG hormone in the sample solutions is verified by Fourier-transform infrared spectroscopy (FTIR), revealing the presence of bands related to functional groups, such as C=O (1630 cm-1), which are associated with proteins and lipids, components of the hCG hormone. Quantification tests for hormone concentrations were carried out by measuring the optical power response of the tapered optical fiber with Au-NPs under the influence of hCG hormone concentrations, ranging from 1 mIU/mL to 100,000 mIU/mL. In the waist of the tapered optical fiber, the evanescent field is amplified because of localized surface plasmons generated by the nanoparticles and the laser radiation through the optical fiber. Experimental results demonstrated a proportional relationship between measured radiation power and hCG concentration, with the optical power response decreasing from 4.45 mW down to 2.5 mW, as the hCG hormone concentration increased from 1 mIU/mL up to 100,000 mIU/mL. Furthermore, the spectral analysis demonstrated a spectral shift of 14.2 nm with the increment of the hCG hormone concentration. The measurement system exhibits promising potential as a sensor for applications in the biomedical and industrial fields.

A new buffering theory of social support and psychological stress.

A dynamical model linking stress, social support, and health has been recently proposed and numerically analyzed from a classical point of view of integer-order calculus. Although interesting observations have been obtained in this way, the present work conducts a fractional-order analysis of that model. Under a periodic forcing of an environmental stress variable, the perceived stress has been analyzed through bifurcation diagrams and two well-known metrics of entropy and complexity, such as spectral entropy and C0 complexity. The results obtained by numerical simulations have shown novel insights into how stress evolves with frequency and amplitude of the perturbation, as well as with initial conditions for the system variables. More precisely, it has been observed that stress can alternate between chaos, periodic oscillations, and stable behaviors as the fractional order varies. Moreover, the perturbation frequency has revealed a narrow interval for the chaotic oscillations, while its amplitude may present different values indicating a low sensitivity regarding chaos generation. Also, the perceived stress has been noted to be highly sensitive to initial conditions for the symptoms of stress-related ill-health and for the social support received from family and friends. This work opens new directions of research whereby fractional calculus might offer more insight into psychology, life sciences, mental disorders, and stress-free well-being.

Dual-Band CPW Graphene Antenna for Smart Cities and IoT Applications.

In this paper, a dual-band graphene coplanar waveguide antenna is designed for smart cities and internet of things applications. A graphene film is chosen as the conductive material for the radiation patches and ground plane with a thickness of 240 µm and an electric conductivity of 3.5 × 105 S/m. The dielectric is glass with a dielectric permittivity of 6 and a thickness of 2 mm. The implementation of the antenna on glass permits the integration of the antenna in smart cities and IoT applications. This antenna is based on two trapezoidal patches that generate the dual-band behavior. The overall dimensions of the antenna are 30 mm × 30 mm × 2 mm. The reflection coefficient, gain, and radiation patterns were measured and compared with the simulations. The antenna covers two frequency bands; the lower band covers the 2.45 GHz ISM band, and the upper band range covers from 4 to 7 GHz.

Prevalence of Dating Violence in Adolescents of Five Colombian Cities / Prevalencia de la Violencia en el Noviazgo en Adolescentes de Cinco Ciudades Colombianas

Abstract The aim of this study was to examine the prevalence and frequency of perpetration and victimization of different types of dating violence (DV), among adolescents from 13 to 19 years old in five capital cities of Colombia (Bogotá, Bucaramanga, Ibagué, Tunja, and Yopal), making comparisons by sex. The Spanish version of the Conflict in Adolescent Dating Relationships Inventory was used and various statistical analyses, including the one-way MANOVA, were performed. The results show a high prevalence of DV, particularly verbal/emotional and bi-directional (almost 90 % of the participants), pointing out that sex could have a statistically significant effect on the prevalence of the different types of DV, being higher the proportion of men who perpetrated sexual violence and higher the proportion of women who perpetrated verbal/emotional and physical violence. These results indicate the need to continue investigating the phenomenon in Colombia, to carry out different prevention campaigns that are sensitive to differences by sex in prevalence.

Resumen El objetivo de este estudio fue examinar la prevalencia y la frecuencia de la perpetración y la victimización de diferentes tipos de violencia en el noviazgo (VN), entre adolescentes de 13 a 19 anos de cinco ciudades capitales de Colombia (Bogotá, Bucaramanga, Ibagué, Tunja y Yopal), efec-tuándose comparaciones por sexo. Se utilizò la versión en espanol del Conflict in Adolescent Dating Relationships Inventory, implementándose varios análisis estadísticos, incluyendo el MANOVA unidireccional. Los resultados evidencian una alta prevalencia de VN, particularmente verbal/ emocional y bi-direccional (casi el 90 % de los participantes), senalando que el sexo podría tener un efecto estadísticamente significativo en las prevalencias de los diferentes tipos de VN, siendo mayor la proporciòn de hombres que ejercieron violencia sexual y mayor el de mujeres que ejercieron violencia verbal/emocional y física. Estos resultados evidencian la necesidad de seguir investigando el fenòmeno en Colombia, para así adelantar diferentes campanas de prevenciòn que sean sensibles a las diferencias por sexo en las prevalencias.

Measurement Invariance and Latent Mean Differences Between American, Spanish and Chinese Adolescents Using the Social Anxiety Scale for Adolescents (SAS-A).

BACKGROUND: Social anxiety is one of the most prevalent disorders among adolescents (Stein et al., 2017). The main aim of this study was to analyze the equivalence of scores on the Social Anxiety Scale for Adolescents (SAS-A) using structural equation modeling and identify differences in latent means of social anxiety in China, Spain, and the USA. METHOD: Random sampling was used to recruit participants, which included 536 Chinese (46% girls), 1,178 Spanish (55.3% girls) and 866 North American (55.1% girls) adolescents. The participants' ages ranged between 14 and 17 years old. RESULTS: The SAS-A three-factor correlated model of social anxiety remained invariant between the Spanish and North American adolescents, but results could not be replicated in the Chinese adolescents [M2 = ΔS-Bχ² (Δdf, p) = 4732.56 (36, < .01)]. Analyses of latent differences between Spain and the USA showed that Spanish adolescents had higher scores than North Americans for Fear of Negative Evaluation (TS = -9.630; d = .44) and for Social Avoidance and General Anxiety towards people (TS = -2.717; d = .12). CONCLUSIONS: The results are interpreted according to the cultural traits of individualism-collectivism and self-construal, and practical implications are discussed.

Measurement Invariance and Latent Mean Differences Between American, Spanish and Chinese Adolescents Using the Social AnxietyScale for Adolescents (SAS-A) / Análisis de Invarianza y Diferencias de Medias Latentes Entre Adolescentes Americanos, Españoles y Chinos Usando la Escala deAnsiedad Social para Adolescentes (SAS-A)

Background: Social anxiety is one of the most prevalent disorders amongadolescents (Stein et al., 2017). The main aim of this study was to analyzethe equivalence of scores on the Social Anxiety Scale for Adolescents(SAS-A) using structural equation modeling and identify differences inlatent means of social anxiety in China, Spain, and the USA. Method:Random sampling was used to recruit participants, which included 536Chinese (46% girls), 1,178 Spanish (55.3% girls) and 866 North American(55.1% girls) adolescents. The participants’ ages ranged between 14 and17 years old. Results: The SAS-A three-factor correlated model of socialanxiety remained invariant between the Spanish and North Americanadolescents, but results could not be replicated in the Chinese adolescents[M2 = ΔS-Bχ2 (Δdf, p) = 4732.56 (36, < .01)]. Analyses of latent differencesbetween Spain and the USA showed that Spanish adolescents had higherscores than North Americans for Fear of Negative Evaluation (TS = -9.630;d = .44) and for Social Avoidance and General Anxiety towards people(TS = -2.717; d = .12). Conclusions: The results are interpreted accordingto the cultural traits of individualism-collectivism and self-construal, andpractical implications are discussed.

Antecedentes: la ansiedadsocial es uno de los trastornos con mayor prevalencia en adolescentes(Stein et al., 2017). Así, el propósito principal de este estudio fue analizarla invarianza de la Escala de Ansiedad Social para Adolescentes (SAS-A) mediante un modelo de ecuaciones estructurales y examinar las diferenciasde medias latentes en ansiedad social en adolescentes de China, España y EE.UU. Método: los participantes se seleccionaron a través de muestreoaleatorio: 534 chinos (46% chicas), 1.178 españoles (55,3% chicas) y866 norteamericanos (55,1% chicas), con edades comprendidas entre los14 y 17 años. Resultados: las puntuaciones del modelo de tres factorescorrelacionados de ansiedad social de la SAS-A resultaron invariantesentre adolescentes españoles y norteamericanos, pero estos resultados nofueron replicados en adolescentes chinos [M2 = ΔS-Bχ2 (Δdf, p) = 4732.56(36, < .01)]. El análisis de medias latentes entre España y EE.UU. mostróque los adolescentes españoles manifestaban niveles más altos de Miedoante las evaluaciones negativas (TS = -9.630; d = .44) y Evitación social yansiedad general hacia las personas (TS = -2.717; d = .12).Conclusiones: estos hallazgos fueron interpretados atendiendo al de individualismo-colectivismo y las concepciones culturales de la propia persona, analizandosus implicaciones prácticas.

Gerbode defect or left ventricular to right atrial shunt. Case report and literature review / Defecto tipo Gerbode o comunicación entre el ventrículo izquierdo y la aurícula derecha. Reporte de un caso y revisión de la literatura

Gerbode defect is a communication from the left ventricle to right atrium and it could be categorized in congenital or acquired. It is a rare condition that can represent as much as 0.08% of all septal defects. Those acquired defects can be associated to endocarditis and after valvular surgery. The objective is to report a case of Gerbode atria-ventricular septal defect in Instituto Nacional de Cardiología Ignacio Chavez. The present case is about a 36 years old male patient with a typical presentation of mitral regurgitation, the echocardiogram reports a perforation in the anterior mitral leaflet and a Gerbode ventricular septal defect, that represents the heterogeneity of the clinical presentation of this pathology, also we show the findings in imaging studies that contributed to diagnosis and its surgical resolution. Gerbode defect is an uncommon pathology, many times associated to other cardiovascular entity, difficulting diagnose. It requires image studies and a complete presurgical evaluation in order to achieve opportune diagnosis.

El defecto tipo Gerbode es una comunicación del ventrículo izquierdo a la aurícula derecha, que puede clasificarse como congénita o adquirida. Es una condición rara que puede representar hasta el 0.08% de los defectos septales congénitos. Los defectos adquiridos pueden asociarse a endocarditis y presentarse también posterior a cambios valvulares. El objetivo es reportar un caso de comunicación interventricular de Gerbode en el Instituto Nacional de Cardiología. Paciente varón, de 36 años, con presentación clínica típica de insuficiencia mitral, ecocardiografía con hallazgo de rotura de la valva anterior de la válvula mitral y comunicación interventricular tipo Gerbode. Se ponen de manifiesto la heterogeneidad clínica con la que se presenta esta patología y los hallazgos de imagen que contribuyen al diagnóstico y su resolución quirúrgica. La comunicación interventricular tipo Gerbode es una patología infrecuente, muchas veces asociada a otra afección cardiovascular, lo que la hace de difícil diagnóstico. Se requieren estudios de imagen y una evaluación preoperatoria completa para su detección oportuna.

Síntomas psicopatológicos y emocionales asociados a malos tratos en parejas de adolescentes de Floridablanca, Colombia / Psychopathological and emotional symptoms associated with abuse in adolescent couples in Floridablanca, Colombia

Diversos estudios han demostrado que los malos tratos en el noviazgo son un problema de alta prevalencia que afecta a adolescentes de diferentes edades y diversos contextos socioculturales, comprometiendo su desarrollo integral y bienestar. El objetivo general de este estudio fue conocer los síntomas psicopatológicos y emocionales asociados a los malos tratos por parte de la pareja entre adolescentes de Floridablanca, Colombia. Los participantes fueron 261 estudiantes de dos colegios de Floridablanca con edades entre los 13 y 19 años (M = 15; DT = 1.80). Los instrumentos utilizados fueron la Conflict in Adolescent Dating Re-lationships Inventory (CADRI), versión española, y la Lista de Síntomas SCL-90-R. Se encontró, teniendo en cuenta la direccionalidad en la violencia de género en el noviazgo, una prevalencia general de un 94.2 % de los participantes. En cuanto al género, el 41 % de los hombres participó en alguno de estos roles (perpetración, victimización y violencia mutua), sin encontrarse diferencias estadísticamente significativas. Además, se hallaron correlaciones estadísticamente significativas entre la puntuación global de victimización y violencia mutua y las escalas del SCL90-R, además de los tres indicadores que reflejan aspectos diferenciales de los síntomas. Los hallazgos se discuten en relación con los desafíos de desarrollo que enfrentan los adolescentes

Several studies have shown that dating abuse is a highly prevalent problem that affects adolescents of different ages and diverse sociocultural contexts, compromising their comprehensive development and well-being. The general objective was to know the psychopathological and emotional symptoms associated with abuse by the couple among adolescents from Floridablanca, Colombia. The participants were 261 students from two Floridablanca schools aged between 13 and 19 years old (M = 15; SD = 1.80). The instruments used were the Conflict in Adolescent Dating Relationships Inventory (CADRI), Spanish version, and the List of Symptoms SCL-90-R. Taking into account the directionality in gender violence in courtship, a general prevalence of 94.2 % of the participants was found. Regarding gender, 41 % of the men participated in one of these roles (perpetration, victimization and mutual violence), with no statistically significant differences being found. In addition, statistically significant correlations were found between the global victimization and mutual violence score and the SCL90-R scales, in addition to the three indicators that reflect differential aspects of the symptoms. Findings are discussed in relation to developmental challenges faced by adolescents

Analysis of mental health in cyberbullying victims and perpetrators in Spanish and Colombian adolescents / Análisis de la salud mental en víctimas y agresores de cyberbullying en adolescentes españoles y colombianos

Abstract Introduction: Due to the advance of information and communication technologies, children may be exposed to the phenomenon known as cyberbullying. The abundant literature and existing research confirm the interest that the consequences of cyberbullying can provoke in the mental health of adolescents. The aims of this work were: (1) To compare the figures of the difficulties in mental health and cyberbullying in adolescents from Spain and Colombia, (2) To analyse the relationship between mental health and being a high degree cyber-perpetrator or cyber-victim owing to mobile phones and Internet, in both countries. Method: A cross-sectional study was employed, in which 1,080 students from Colombia (11 to 17 years old) and 430 students from Spain (12 to 17 years old) participated through the SDQ, CYBVYC and CYBAGRESS questionnaires. T student, correlations, and the Kruskal Wallis test were used. Results: Difficulties in Emotional symptoms, Conduct problems, Hyperactivity, Peer problems, and the Total difficulties scores were higher in Colombia than in Spain. Colombian adolescents scored higher in cyber-victimization (CYBVYC-Internet) and cyber-perpetration (CYBAGRESS) than Spanish adolescents. However, cyber-victimisation (CYBVYC-Mobile) by way of mobile phone was higher in Spain. Moreover, those who had serious victim and serious perpetrator profiles (scores equal to or higher than the 95th percentile in the CYBAGRESS and CYBVYC scales) presented higher difficulties in Emotional symptoms, Conduct problems, Hyperactivity, and Peer problems than those who were not classified as pertaining to those profiles, in both countries. A positive and direct correlation between difficulties in mental health, cyber-victimisation, and cyber-perpetration exist, regardless of Internet or mobile phone use. Conclusions: Results show how cyberbullying has similar effects on the mental health of Spanish and Colombian teenagers. Finally, there exists a relationship between being a cyberbullying victim or perpetrator and obtaining a higher total score in mental health difficulties among adolescents in both countries.

Resumen Introducción: Debido al avance de las nuevas tecnologías los menores pueden estar expuestos al fenómeno conocido como cyberbullying. La abundante literatura e investigaciones existentes constatan el interés que pueden provocar las consecuencias del cyberbullying en la salud mental de los adolescentes. Los objetivos del trabajo fueron: (1) Comparar la puntuación en dificultades en salud mental y cyberbullying en adolescentes de España y Colombia, (2) Analizar en ambos países la relación entre salud mental y aquellos perfiles clasificados como nivel severo de ciberacosador y cibervíctima, a través del móvil o internet. Método: Estudio transversal, en el que participaron 1080 estudiantes de Colombia (11 a 17 años) y 430 estudiantes de España (12 a 17 años) a través de los cuestionarios SDQ, CYBVYC y CYBAGRESS. Se utilizaron una T de student, correlaciones y la prueba de Kruskal Wallis. Resultados: Las puntuaciones en dificultades en Síntomas emocionales, Problemas de conducta, Hiperactividad, Problemas con compañeros y la Puntuación total de dificultades fueron mayores en Colombia que en España. Los adolescentes colombianos obtuvieron mayores puntaciones en cibervictimización (CYBVYC-internet) y ciberagresión (CYBAGRESS) que los adolescentes españoles. Sin embargo, las puntuaciones en cibervictimización a través del móvil (CYBVYC-móvil) fueron superiores en España. Por otro lado, en términos generales, aquellos adolescentes categorizados como ciberagresores o cibervíctimas severos (puntuaciones iguales o superiores al percentil 95) obtuvieron mayores puntuaciones en ambos países, en Síntomas emocionales, Problemas de conducta, Hiperactividad y Problemas con compañeros que aquellos que no fueron clasificados bajo esta consideración. Existe correlación positiva y directa entre la salud mental, cibervictimización y ciberagresión, independientemente de su realización por medio de internet o el teléfono móvil. Conclusiones: Existen resultados similares entre el ciberacoso y la salud mental en los adolescentes españoles y colombianos. Finalmente, existe una relación en ambos países entre ser víctima o acosador en ciberacoso y tener mayores dificultades en salud mental para ambos perfiles.

Violencia intragénero entre parejas homosexuales en universitarios de Bucaramanga, Colombia / Intra-gender violence in homosexual university students from Bucaramanga, Colombia

Resumen Introducción: Las investigaciones sobre violencia en la pareja se han centrado principalmente en el estudio de las parejas heterosexuales y son escasos los datos sobre la violencia de parejas del mismo sexo en el noviazgo. Objetivo: Analizar la violencia intragénero entre parejas homosexuales en universitarios de Bucaramanga. Materiales y métodos: Investigación cuantitativa con muestreo tipo bola de nieve mediante el cual se obtuvo una población de 132 participantes mayores de 18 años. Se aplicó el instrumento pre-validado Lista de Chequeo de Experiencias de Maltrato en la Pareja. Los datos se analizaron con el software SPSS, versión 23, mediante la prueba X 2 y ANOVA Unidireccional, considerando un α=0,05. Resultados: El 91,7% de los participantes fue violentado por lo menos con una de las conductas de estudio, la violencia predominante en las parejas fue la psicológica, seguida de la violencia emocional, la violencia física, la violencia sexual y, por último, la violencia económica. Se encontraron diferencias significativas para algunos ítems del instrumento entre hombres y mujeres. Conclusiones: La violencia psicológica tuvo mayor presencia en los participantes.

Abstract Introduction: Research on partner violence has mainly focused on studies of heterosexual couples, while data on same-sex dating violence are scarce. Objective: To analyze intra-gender violence in homosexual university couples in Bucaramanga. Materials and methods: A quantitative research with a snowball sampling approach was applied to obtain a population of 132 participants who were older than 18 years of age. The pre-validated instrument Check List for Partner Abuse Experience was used. Data were analyzed with SPSS software (version 23), using the X2 test and one-way ANOVA, considering an α=0.05. Results: 91.7% of participants experience violence with at least one of the studied behaviors. Psychological violence was the most predominant form in the studied couples, followed by emotional, physical, sexual, and economic violence. Significant differences between males and females were found for some items of the instrument. Conclusions: Psychological violence was the most frequent in the study's participants.

Stabilization and Synchronization of a Complex Hidden Attractor Chaotic System by Backstepping Technique.

In this paper, the stabilization and synchronization of a complex hidden chaotic attractor is shown. This article begins with the dynamic analysis of a complex Lorenz chaotic system considering the vector field properties of the analyzed system in the Cn domain. Then, considering first the original domain of attraction of the complex Lorenz chaotic system in the equilibrium point, by using the required set topology of this domain of attraction, one hidden chaotic attractor is found by finding the intersection of two sets in which two of the parameters, r and b, can be varied in order to find hidden chaotic attractors. Then, a backstepping controller is derived by selecting extra state variables and establishing the required Lyapunov functionals in a recursive methodology. For the control synchronization law, a similar procedure is implemented, but this time, taking into consideration the error variable which comprise the difference of the response system and drive system, to synchronize the response system with the original drive system which is the original complex Lorenz system.

Zaragoza technique of laparoscopic appendicectomy.

INTRODUCTION: Appendectomy is one of the most frequent emergency surgical procedures, currently with a preference for laparoscopic management worldwide. OBJECTIVE: To report a new laparoscopic appendectomy technique and its results. MATERIAL AND METHODS: Cohort study of patients with a diagnosis of appendicitis who are managed laparoscopically. In a total 1063 patients, 148 were operated on with the Zaragoza technique during the period from January 2002 to December 2018. The technique consists of making a window in the appendicular base between the meso and the appendicular wall, two prolene or silk sutures are placed, and the cecal appendix is cut between the two sutures, finally the mesoappendix is sectioned with a harmonic scalpel or bipolar clamp. RESULTS: From our results, we had 1.4% residual abscesses, 1.4% umbilical surgical wound infection and 0% mortality. DISCUSSION: Various laparoscopic management methods for appendectomy are reported in the literature, with a wide range in the results. We have obtained good results in patients subjected to our technique. CONCLUSIONS: The Zaragoza technique for laparoscopic appendectomy is an effective and safe option that prevents excessive manipulation of the inflamed appendix and is easily reproducible.

A fractional-order SIRD model with time-dependent memory indexes for encompassing the multi-fractional characteristics of the COVID-19.

COVID-19 is a novel coronavirus affecting all the world since December last year. Up to date, the spread of the outbreak continues to complicate our lives, and therefore, several research efforts from many scientific areas are proposed. Among them, mathematical models are an excellent way to understand and predict the epidemic outbreaks evolution to some extent. Due to the COVID-19 may be modeled as a non-Markovian process that follows power-law scaling features, we present a fractional-order SIRD (Susceptible-Infected-Recovered-Dead) model based on the Caputo derivative for incorporating the memory effects (long and short) in the outbreak progress. Additionally, we analyze the experimental time series of 23 countries using fractal formalism. Like previous works, we identify that the COVID-19 evolution shows various power-law exponents (no just a single one) and share some universality among geographical regions. Hence, we incorporate numerous memory indexes in the proposed model, i.e., distinct fractional-orders defined by a time-dependent function that permits us to set specific memory contributions during the evolution. This allows controlling the memory effects of more early states, e.g., before and after a quarantine decree, which could be less relevant than the contribution of more recent ones on the current state of the SIRD system. We also prove our model with Italy's real data from the Center for Systems Science and Engineering (CSSE) at Johns Hopkins University.

Nonlinear Dynamics and Entropy of Complex Systems with Hidden and Self-Excited Attractors II.

According to the pioneering work of Leonov and Kuznetsov [...].

Synchronization of a Non-Equilibrium Four-Dimensional Chaotic System Using a Disturbance-Observer-Based Adaptive Terminal Sliding Mode Control Method.

In this paper, dynamical behavior and synchronization of a non-equilibrium four-dimensional chaotic system are studied. The system only includes one constant term and has hidden attractors. Some dynamical features of the governing system, such as invariance and symmetry, the existence of attractors and dissipativity, chaotic flow with a plane of equilibria, and offset boosting of the chaotic attractor, are stated and discussed and a new disturbance-observer-based adaptive terminal sliding mode control (ATSMC) method with input saturation is proposed for the control and synchronization of the chaotic system. To deal with unexpected noises, an extended Kalman filter (EKF) is implemented along with the designed controller. Through the concept of Lyapunov stability, the proposed control technique guarantees the finite time convergence of the uncertain system in the presence of disturbances and control input limits. Furthermore, to decrease the chattering phenomena, a genetic algorithm is used to optimize the controller parameters. Finally, numerical simulations are presented to demonstrate the performance of the designed control scheme in the presence of noise, disturbances, and control input saturation.

Modification of the Logistic Map Using Fuzzy Numbers with Application to Pseudorandom Number Generation and Image Encryption.

A modification of the classic logistic map is proposed, using fuzzy triangular numbers. The resulting map is analysed through its Lyapunov exponent (LE) and bifurcation diagrams. It shows higher complexity compared to the classic logistic map and showcases phenomena, like antimonotonicity and crisis. The map is then applied to the problem of pseudo random bit generation, using a simple rule to generate the bit sequence. The resulting random bit generator (RBG) successfully passes the National Institute of Standards and Technology (NIST) statistical tests, and it is then successfully applied to the problem of image encryption.

Nonlinear Dynamics and Entropy of Complex Systems with Hidden and Self-Excited Attractors.

In the last few years, entropy has been a fundamental and essential concept in information theory [...].