Validación de instrumento para medir el nivel de conocimiento de estudiantes de posgrado y docentes universitarios sobre la ley de trabajo del cirujano dentista

Objective: To build and validate an instrument to measure the level of knowledge about the Law that regulates the work of the dental surgeon in the Peruvian territory (Law No. 27878) of postgraduate students and teachers of the Stomatology Career of the Scientific University of South. Peru. Material and methods: The sample consisted of 38 dental surgeons, participants in the postgraduate program (20) and professors (18) of the Stomatology Career at the Universidad Científica del Sur. A structured questionnaire of 15 questions was developed based on the articles of Law No. 27878. Results: It was approved by Expert Judgment and submitted to Aiken's V with an average result of 0.95. A moderate level of correlation was obtained through the Pearson Correlation Coefficient and a Cronbach's Alpha of 0.8. Through the Exploratory Factor Analysis, 3 dimensions were formed. Conclusions: The instrument was correctly validated through 4 validity　tests. The level of knowledge of postgraduate students and teachers was very good in 60.5%.Objetivo: Construir y validar un instrumento para medir el nivel de conocimiento de los　estudiantes de posgrado y docentes de la Carrera de Estomatología de la Universidad Científica del Sur sobre la Ley que regula el trabajo del cirujano dentista en el territorio peruano (Ley N.° 27878). Materiales y métodos: La muestra fue de 38 cirujanos dentistas, participantes del programa de posgrado (20) y profesores (18) de la Carrera de Estomatología de la Universidad Científica del Sur. Se elaboró un cuestionario estructurado de 15 preguntas con base en los artículos de la Ley N.° 27878. Resultados: Fue aprobado por juicio de expertos y sometido a la V de Aiken, con un resultado promedio de 0,95. Obtuvo un nivel de correlación moderado a través del coeficiente de　correlación de Pearson y un alfa de Cronbach de 0,8. A través del análisis factorial exploratorio, se conformaron 3 dimensiones. Conclusiones: El instrumento se validó correctamente a través de 4 pruebas de validez. El nivel de conocimiento de los estudiantes de posgrado y docentes fue muy bueno en un 60,5%

β-Ga₂O₃ nanowires for an ultraviolet light selective frequency photodetector

The behaviour of ß-Ga₂O₃ nanowires as photoconductive material in deep ultraviolet photodetectors to operate in the energy range 3.0-6.2 eV has been investigated. The nanowires were grown by a catalyst-free thermal evaporation method on gallium oxide substrates. Photocurrent measurements have been carried out on both undoped and Sn-doped Ga₂O₃ nanowires to evidence the influence of the dopant on the photodetector performances. The responsivity spectrum of single nanowires show maxima in the energy range 4.8-5.4 eV and a strong dependence on the pulse frequency of the excitation light has been observed for undoped nanowires. Our results show that the responsivity of beta- Ga₂O₃ nanowires can be controlled by tuning the chopper frequency of the excitation light and/ or by doping of the nanowires. Non-linear behavior in characteristic current-voltage curves has been observed for Ga₂O₃ : Sn nanowires. The mechanism leading to this behaviour has been discussed and related to space-charged-limited current effects. In addition, the responsivity achieved by doped nanowires at lower bias is higher than for undoped ones

Synergy between pyroelectric and photovoltaic effects for optoelectronic nanoparticle manipulation

© 2019 Optical Society of America. Users may use, reuse, and build upon the article, or use the article for text or data mining, so long as such uses are for non-commercial purposes and appropriate attribution is maintained. All other rights are reserved.The combined action of the pyroelectric (PY) and photovoltaic (PV) effects, exhibited by z-cut LiNbO3:Fe substrates, has been investigated for particle trapping and patterning applications. The novel hybrid procedure provides new possibilities and versatility to optoelectronic manipulation on LiNbO3 substrates. It has allowed obtaining periodic and arbitrary 2D patterns whose particle density distribution is correlated with the light intensity profile but can be tuned through ΔT according to the relative strength of the PV and PY effects. A relevant result is that the PY and PV contributions compete for a ΔT range of 1-20 °C, very accessible for experiments. Moreover, the synergy of the PY and PV has provided two additional remarkable applications: i) A method to measure the PV field, key magnitude for photovoltaic optoelectronic tweezers. Using this method, the minimum field needed to obtain a particle pattern has been determined, resulting relatively high, E~60 kV/cm, and so, requiring highly doped crystals when only using the PV effect. ii) An strategy combining the PY and PV to get particle patterning in samples inactive for PV trapping when the PV field value is under that thresholdMinisterio de Ciencia, Innovación y Universidades of Spain (MAT2014-57704-C3, MAT2017-83951-R); Universidad Politécnica de Madrid (RR01/2016

Análisis modal comparado entre modelos virtuales 2d y 3d aplicado a un Cube Sat

El siguiente trabajo presenta un análisis modal comparado entre modelos virtuales 2D y 3D, para validar la sistematización de una metodología de análisis completo de Ingeniería Asistida por Computadora, ejemplificada en la aplicación a un modelo de nano satélite tipo Cube Sat. Se detallan los requerimientos de las especificaciones técnicas, condiciones estructurales, cargas, restricciones y frecuencias de vibración, que sufre este satélite al momento de su despegue y durante su órbita. Posteriormente se aplica al Diseño Asistido por Computadora la solicitud del análisis de respuesta dinámica al modelo de su estructura principal simplificada, utilizando el Método de los Elementos Finitos. Las simulaciones incluyen el análisis dinámico de frecuencias naturales y modos de vibración libre. La comparación se lleva a cabo con las herramientas de un Sistema de Ingeniería Basada en el Conocimiento que permiten optimizar la elaboración de diseños mecánicos y reducir tiempos de solución ante nuevos retos de simulación

Ballistic Localization in Quasi-1D Waveguides with Rough Surfaces

Structure of eigenstates in a periodic quasi-1D waveguide with a rough surface is studied both analytically and numerically. We have found a large number of "regular" eigenstates for any high energy. They result in a very slow convergence to the classical limit in which the eigenstates are expected to be completely ergodic. As a consequence, localization properties of eigenstates originated from unperturbed transverse channels with low indexes, are strongly localized (delocalized) in the momentum (coordinate) representation. These eigenstates were found to have a quite unexpeted form that manifests a kind of "repulsion" from the rough surface. Our results indicate that standard statistical approaches for ballistic localization in such waveguides seem to be unappropriate.Comment: 5 pages, 4 figure

Direct observation of tunnelled intergrowth in SnO2/Ga2O3 complex nanowires

beta-Ga_2O_3 intergrowths have been revealed in the SnO_2 rutile structure when SnO_2/Ga_2O_3 complex nanostructures are grown by thermal evaporation with a catalyst-free basis method. The structure is formed by a Ga_2O_3 nanowire trunk, around which a rutile SnO_2 particle is formed with [001] aligned to the [010] Ga_2O_3 trunk axis. Inside the SnO_2 particle, beta-Ga_2O_3 units occur separated periodically by hexagonal tunnels in the (210) rutile plane. Orange (620 nm) optical emission from tin oxide, with a narrow linewidth indicating localised electronic states, may be associated with this beta-Ga_2O_3 intergrowth

Association between heavy metals and metalloids in topsoil and mental health in the adult population of Spain

Despite the biological plausibility of the association between heavy metal exposure and mental health disorders, epidemiological evidence remains scarce. The objective was to estimate the association between heavy metals and metalloids in soil and the prevalence of mental disorders in the adult population of Spain. Methods Individual data came from the Spanish National Health Survey 2011–2012, 18,073 individuals residing in 1772 census sections. Mental health was measured with the 12-item General Health Questionnaire. The concentration estimates of heavy metal and metalloid levels in topsoil (upper soil horizon) came from the Geochemical Atlas of Spain based on 13,317 soil samples. Levels of lead (Pb), arsenic (As), cadmium (Cd) and manganese (Mn) were estimated in each census section by “ordinary Kriging”. Odds ratios (OR) were calculated by multilevel logistic regression models. Results Compared with the lowest Pb concentration levels quartile, the OR for the second quartile was 1.29 (95%CI: 1.11–1.50), increasing progressively to 1.37 (95%CI: 1.17–1.60) and 1.51 (95%CI: 1.27–1.79) in the third and fourth quartiles, respectively. For As, the association was observed in the third and fourth quartiles: 1.21 (95%CI: 1.04–1.41) and 1.42 (95% CI: 1.21–1.65), respectively. Cd was associated also following a gradient from the second quartile: 1.34 (95%CI: 1.15–1.57) through the fourth: 1.84 (95%CI: 1.56–2.15). In contrast, Mn only showed a positive association at the second quartile. Additionally, individuals consuming vegetables > once a day the OR for the fourth quartile of Pb concentration, vs. the first, increased to 2.93 (95%CI: 1.97–4.36); similarly for As: 3.00 (95%CI: 2.08–4.31), and for Cd: 3.49 (95%CI: 2.33–5.22). Conclusions Living in areas with a higher concentration of heavy metals and metalloids in soil was associated with an increased probability of having a mental disorder. These relationships were strengthened in individuals reporting consuming vegetables > once a dayThis work was supported by the Institute of Health Carlos III, Ministry of Science Innovation and Universities [grant number PI15CIII/00034, PI14CIII/00065 and PI17CIII/00040