All-optical radiofrequency modulation of Anderson-localized modes

All-optical modulation of light relies on exploiting intrinsic material nonlinearities. However, this optical control is rather challenging due to the weak dependence of the refractive index and absorption coefficients on the concentration of free carriers in standard semiconductors. To overcome this limitation, resonant structures with high spatial and spectral confinement are carefully designed to enhance the stored electromagnetic energy, thereby requiring lower excitation power to achieve significant nonlinear effects. Small mode-volume and high quality (Q)-factor cavities also offer an efficient coherent control of the light field and the targeted optical properties. Here, we report on optical resonances reaching Q - 10^5 induced by disorder on novel photonic/phononic crystal waveguides. At relatively low excitation powers (below 1 mW), these cavities exhibit nonlinear effects leading to periodic (up to - 35 MHz) oscillations of their resonant wavelength. Our system represents a test-bed to study the interplay between structural complexity and material nonlinearities and their impact on localization phenomena and introduces a novel functionality to the toolset of disordered photonics

Ensayo Instagram

In the era of the Internet and large-scale communications, the applications and social networks that share images have become one of the main ways of interacting through the network of networks; This is how I will analyze from different points of view the perspective that I comment but in a specific social network, specialized in images, well at least that's how it was born in its beginnings, however it has become much more interactive since at present, not only they share photos and videos, but also you can even chat, something that could not be done in this specific social network; I mean Instagram

Percepción de los egresados sanmarquinos respecto de su formación pedagógica en el marco de la educación intercultural

The main objective of the study is to analyze the perceptions of the graduates of the Faculty of Education in the National University of San Marcos regarding their pedagogical training in the framework of intercultural education. Among the specific objectives, the study investigates about graduates’ perceptions on the contents taught and the methodologies used by their professors, also about their perceptions on their internship and student coexistence in a markedly heterogeneous academic and social context. The approach of the study is qualitative, and the main data collection technique is the semi-structured in-depth interview. A total of 10 informants who completed their studies in 2018 were interviewed. The interviews were conducted between 2019 and February 2020 (pre-pandemic). Among the main results, it is found that both the curricular programming and the methodologies used by professors do not consider nor include the principles of intercultural pedagogy. Among the conclusions, in the Faculty of Education of San Marcos rules a monocultural curriculum that reproduces the hegemonic model, even though the main characteristic of the student population is their cultural and linguistic diversity.El estudio desarrollado tiene como objetivo central analizar las percepciones de los egresados de la Facultad de Educación en la Universidad Nacional Mayor de San Marcos respecto de su formación pedagógica en el marco de la educación intercultural. Entre los objetivos específicos, el estudio indaga en torno a sus percepciones respecto de los contenidos impartidos y las metodologías empleadas por sus docentes, así como sobre sus prácticas preprofesionales y la convivencia estudiantil en un contexto académico y social marcadamente heterogéneo. El enfoque del estudio es cualitativo y la técnica principal de recolección de información es la entrevista semiestructurada y a profundidad. Se trabajó con un total de 10 informantes que culminaron sus estudios en el 2018. Las entrevistas se desarrollaron entre el 2019 y febrero del 2020 (prepandemia). Entre los principales resultados, se encuentra que tanto la programación curricular como las metodologías empleadas por los docentes no consideran ni incluyen los principios de la pedagogía intercultural. Entre las conclusiones, en la Facultad de Educación de San Marcos rige un currículum de corte monocultural y reproductor del modelo hegemónico, pese a que la característica principal de dicha población estudiantil es su diversidad cultural y lingüística. &nbsp

Ensayo Instagram

In the era of the Internet and large-scale communications, the applications and social networks that share images have become one of the main ways of interacting through the network of networks; This is how I will analyze from different points of view the perspective that I comment but in a specific social network, specialized in images, well at least that's how it was born in its beginnings, however it has become much more interactive since at present, not only they share photos and videos, but also you can even chat, something that could not be done in this specific social network; I mean Instagram

Probing the electron-phonon coupling in ozone-doped graphene by Raman spectroscopy

We have investigated the effects of ozone treatment on graphene by Raman scattering. Sequential ozone short-exposure cycles resulted in increasing the $p$ doping levels as inferred from the blue shift of the 2$D$ and $G$ peak frequencies, without introducing significant disorder. The two-phonon 2$D$ and 2$D'$ Raman peak intensities show a significant decrease, while, on the contrary, the one-phonon G Raman peak intensity remains constant for the whole exposure process. The former reflects the dynamics of the photoexcited electrons (holes) and, specifically, the increase of the electron-electron scattering rate with doping. From the ratio of 2$D$ to 2$D$ intensities, which remains constant with doping, we could extract the ratio of electron-phonon coupling parameters. This ratio is found independent on the number of layers up to ten layers. Moreover, the rate of decrease of 2$D$ and 2$D'$ intensities with doping was found to slowdown inversely proportional to the number of graphene layers, revealing the increase of the electron-electron collision probability

Mechanical oscillations in lasing microspheres

We investigate the feasibility of activating coherent mechanical oscillations in lasing microspheres by modulating the laser emission at a mechanical eigenfrequency. To this aim, 1.5% Nd3+:Barium-Titanium-Silicate microspheres with diameters around 50 {\mu}m were used as high quality factor (Q>10^6) whispering gallery mode lasing cavities. We have implemented a pump-and-probe technique in which the pump laser used to excite the Nd3+ ions is focused on a single microsphere with a microscope objective and a probe laser excites a specific optical mode with the evanescent field of a tapered fibre. The studied microspheres show monomode and multi-mode lasing action, which can be modulated in the best case up to 10 MHz. We have optically transduced thermally-activated mechanical eigenmodes appearing in the 50-70 MHz range, the frequency of which decreases with increasing the size of the microspheres. In a pump-and-probe configuration we observed modulation of the probe signal up to the maximum pump modulation frequency of our experimental setup, i.e., 20 MHz. This modulation decreases with frequency and is unrelated to lasing emission, pump scattering or thermal effects. We associate this effect to free-carrier-dispersion induced by multiphoton pump light absorption. On the other hand, we conclude that, in our current experimental conditions, it was not possible to resonantly excite the mechanical modes. Finally, we discuss on how to overcome these limitations by increasing the modulation frequency of the lasing emission and decreasing the frequency of the mechanical eigenmodes displaying a strong degree of optomechanical coupling.Comment: 17 pages, 5 figure

Semiconducting properties of layered cadmium sulphide-based hybrid nanocomposites

A series of hybrid cadmium salt/cationic surfactant layered nanocomposites containing different concentrations of cadmium sulphide was prepared by exchanging chloride by sulphide ions in the layered precursor CdXx(OH)y(CnTA)z in a solid phase/gas reaction, resulting in a series of layered species exhibiting stoichiometries corresponding to CdSvXx(OH)y(CnTA)z, constituted by two-dimensional CdCl2/CdS ultra-thin sheets sandwiched between two self-assembled surfactant layers. The electronic structure of CdS in the nanocomposite is similar to that of bulk, but showing the expected features of two-dimensional confinement of the semiconductor. The nanocomposite band gap is found to depend in a non-linear manner on both the length of the hydrocarbon chain of the surfactant and the concentration of the sulphide in the inorganic sheet. The products show photocatalytic activity at least similar and usually better than that of "bulk" CdS in a factor of two

Evaluación del uso del ND-YAG Láser para el Tratamiento de la Operación Capsular Posterior en Pacientes con Pseudofaquia

Antecedentes: Las cataratas son patologías de alta prevalencia en pacientes de más de 75 años. El tratamiento de esta anomalía frecuentemente se complica con el desarrollo de opacificación capsular posterior generalmente a los 5 años. No existe tratamiento clínico para esta alteración. Y actualmente es muy popular el uso del láser Nd-YAG para su resolución, lo que ha reemplazado prácticamente el uso de la cirugía con bisturí frío. A pesar de esto su uso ha sido cuestionado. En el hospital “Dr. Teodoro Maldonado Carbo” esta tecnología se viene empleando desde hace tiempo sin que se hayan reportado los resultados. Objetivos: Evaluar los resultados del manejo de la opacidficación capsular posterior en pacientes con pseudofaquia tratados con láser Nd-YAG en esta institución Método: Estudio observacional, tipo reporte de casos. Análisis Estadístico: Frecuencias simples, porcentajes, promedio y desviación estándar. Resultados: La edad promedio de los paciente incluidos en el estudio fue de 68 ± 13 años, mayoritariamente varones (3:2). La intervención se efectuó generalmente en el ojo izquierdo (54%). El 48% de estos pacientes tuvo patologías concomitantes no oftálmica, principalmente la HTA (35%). La presencia de patología oftálmica concomitante se informó en el 47% de los casos, con mayor frecuencia catarata (34%). La tasa de complicaciones fue del 2 x 100 casos. Los pacientes sin ninguna alteración mejoraron en el 100%, los pacientes con patología no oftálmica en el 75% y los pacientes con patología oftálmica en el 72%. Conclusiones: La utilización del láser Nd-YAG para el tratamiento de la OCP posterior a pseudofaquia es una intervención terapéutica altamente segura debido a que se relaciona con una tasa muy baja de complicaciones y una alta tasa de mejora visual

Perspectiva de g?nero: representa??es sociais sobre o homem no processo da gravidez e do nascimento

O processo da gravidez e do nascimento (PGN) ? ainda considerado como uma fun??o da mulher. Isso geralmente ? influenciado pelo determinismo biol?gico que permite ? mulher engravidar e ter filhos. Embora, ? indispens?vel reconhecer que esse processo, desde o seu inicio, tamb?m envolve diretamente ao homem. Mas, al?m do biol?gico, aquela assina??o feminina que se d? ao PGN, tem uma forte influ?ncia social, donde os estere?tipos de g?nero tradicionais cumprem um papel determinante. Neste sentido valorizando a import?ncia do envolvimento do homem no dito processo, foi realizada a presente pesquisa de abordagem qualitativa. O presente estudo teve por objetivo analisar as representa??es sociais sobre o homem no processo da gravidez e do nascimento do filho (a), considerando os personagens envolvidos: homem, mulher e profissional de sa?de. A pesquisa foi realizada na maternidade do Hospital Nossa Senhora da Sa?de da cidade de Diamantina. Foram realizadas entrevistas semiestruturadas nos 17 participantes, dos quais foram 5 mulheres/m?es, 5 homens/pa?s e 7 profissionais de sa?de; sendo esse n?mero definido em cada grupo por o crit?rio de satura??o. As entrevistas foram gravadas, transcritas e submetidas ? an?lise de conte?do, juntamente com os dados obtidos pela observa??o participante que foi a segunda t?cnica de recolec??o de dados. O analise de conte?do permitiu identificar quatro grandes categorias: Estere?tipos de g?nero, profissionais de sa?de e a participa??o do homem, fatores externos na participa??o do homem e benef?cios da participa??o do homem, no PGN respectivamente. Em sentido geral o PGN tem ainda a representa??o de ser de responsabilidade e participa??o basicamente feminina. Isso ? mais evidente em etapas relacionadas ao planejamento familiar e durante a gravidez, pois durante o parto e o nascimento percebe-se certa aproxima??o na participa??o do homem, mais enfatizando sua presencia como s?mbolo de companhia, fortaleza e seguran?a para a m?e. Evidencia-se que os estere?tipos de g?nero tradicionais, aqueles que refor?am a ideia de que o processo em quest?o ? de responsabilidade basicamente feminina e que desligam ao homem dos cuidados e da assist?ncia sanit?ria que envolve esse processo, est?o fortemente arraigados n?o s? nos homens, m?s tamb?m nas mulheres e nos mesmos profissionais de sa?de participantes, que ?s vezes refor?am esses estere?tipos no seu agir profissional. Um aspecto relevante que surgiu na presente pesquisa ? que o trabalho de parto e o parto s?o cen?rios de confronta??o, ambival?ncia e dualidade para os homens, pois convergem dois tipos de masculinidade. Assim por um lado ? um cen?rio que replica algumas caracter?sticas da masculinidade hegem?nica: o homem como s?mbolo de fortaleza e seguran?a. Por outro lado ? uma etapa muito sens?vel, que permite que os homens demostrem alguns sentimentos como medo, dor e inseguran?a, carater?sticas que v?o ? contra da masculinidade tradicional, mais que oferece uma janela de mudan?a da masculinidade hegem?nica fortemente mantida na sociedade. Nesse contexto, ? importante que os profissionais de sa?de, tornem-se agentes de mudan?a e promovam partos mais humanizados e acolhedores, considerando como ponto chave a perspectiva de g?nero nesse processo, mas tamb?m na sa?de sexual e reprodutiva em geral.Disserta??o (Mestrado Profissional) ? Programa de P?s-Gradua??o em Sa?de, Sociedade e Ambiente, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2017.The pregnancy and birth process (PBP) are still considered as women function. This generally is influenced by the biological determinism that has the woman during the pregnancy, of having children . Nevertheless, it is indispensable to admit that this process, from his beginning, also involves directly the man. But, besides the biological thing, the PBP has a strong social influence as famenine assignment, where the traditional gender stereotypes are still determinant. In this respect, valuing the importance of involving the man in this process, there was realized the present qualitative boarding investigation. The present study had as analyze the social representations of the man in the process of the pregnancy and the birth of his/her children, considering the prominent figures: man, woman and health professional. The investigation was realized in the Hospital Nossa Senhora da Sa?de in the city of Diamantina, Brazil. There were realized semistructured interviews in 17 participants, of which they were 5 women / mothers, 5 men / father and 7 health professionals; being this number defined by the saturation criterion. The interviews were recorded, transcribed and submitted to the analysis of content, nitedly with the information obtain edby the observation participant, who was the second technique of compilation of information. The analysis of contental lowed to identify four big categories: Gender Stereotypes, health professionals, external factors, and benefits of the men participation in the PBP respectively. In general sense the PBP it has still there presentation of being of feminine responsibility. This is more evident in stages related to the familiar planning during the pregnancy, so during the child birthand the birth certain men approximation is perceived, but emphasizing that presence as a symbol of company, strength and security for women. There is demonstrated that the traditional gender stereotypes, those that reinforce the idea of that the process in question is basically feminine responsibility and left men out of the care sand sanitary assistance involved in this process. These ideas are strongly deep-rooted not only in men, but also in women, and health professionals participants, who sometimes reinforce these stereotypes in their sanitary activity. One relevant aspect that emerged in the present investigation is that labor and delivery itself are scenarios of confrontation, ambivalence and duality for men, since two types of masculinity converge. Thus, on the one hand, it is a scenario that replicates some characteristics of hegemonic masculinity: man as a symbol of strength and security. On the other hand is a very sensitive stage, which allows men to show some feelings such as fear, pain, insecurity, characteristics that go against traditional masculinity, but offers a window of change of hegemonic masculinity that is Strongly maintained in society. In this context, it is important that health professionals become agents of change and promote more humanized and welcoming deliveries, considering as a key point the gender perspective in this process, as well as in sexual and reproductive health in general.El proceso del embarazo e del nacimiento (PEN) es considerado como funci?n de la mujer. Esto est? influenciado por el determinismo biol?gico que tiene la mujer del embarazo, de tener hijos. Pero, es indispensable reconocer que este proceso, desde su inicio, tambi?n involucra directamente al hombre. Adem?s de lo biol?gico, aquella asignaci?n femenina que se le da al PEN, tiene una fuerte influencia social, donde los estereotipos de g?nero tradicionales cumplen un papel determinante. En este sentido, valorando la importancia de involucrar al hombre en ese proceso, fue realizada la presente investigaci?n cualitativo. El estudio tuvo como objetivo analizar las representaciones sociales del hombre en el proceso del embarazo y el nacimiento del hijo(a), considerando a los personajes envueltos: hombre, mujer y profesional de salud. Se realizado en el Hospital Nossa Senhora da Sa?de en Diamantina. Fueron realizadas entrevistas semiestructuradas en los 17 participantes, de los cuales fueron madres, 5 padres y 7 profesionales de salud; siendo ese n?mero definido por el criterio de saturaci?n. Las entrevistas fueron grabadas, transcritas e sometidas al an?lisis de contenido, juntamente con los datos obtenidos por la observaci?n participante. El an?lisis de contenido permiti? identificar cuatro grandes categor?as: Estereotipos de g?nero, profesionales de salud, factores externos, e beneficios, de la participaci?n del hombre en el PEN respectivamente. En sentido general el PEN tiene a?n la representaci?n de ser de responsabilidad femenina. Esto es m?s evidente en etapas relacionadas a la planificaci?n familiar e durante el embarazo, pues durante el parto e el nacimiento se percibe cierta aproximaci?n en la participaci?n del hombre, pero enfatizando esa presencia como s?mbolo de compa??a, fortaleza e seguridad para la mujer. Se evidencia que los estereotipos de g?nero tradicional, aquellos que refuerzan la idea de que el proceso en cuesti?n es de responsabilidad b?sicamente femenina e que desligan al hombre de los cuidados e de la asistencia sanitaria que involucra ese proceso, est?n fuertemente arraigados no s?lo en los hombres, sino tambi?n en las mujeres, e, en los mismos profesionales de salud participantes, quienes a veces refuerzan esos estereotipos en su actividad sanitaria. Un aspecto relevante que surgi? en la presente investigaci?n es que el trabajo de parto y el parto en s?, son escenarios de confrontaci?n, ambivalencia e dualidad para los hombres, pues convergen dos tipos de masculinidad. As?, por un lado es un escenario que replica algunas caracter?sticas de la masculinidad hegem?nica: el hombre como s?mbolo de fortaleza e seguridad. Por otro lado es una etapa muy sensible, que permite que los hombres demuestren algunos sentimientos como el miedo, el dolor, la inseguridad, caracter?sticas que van en contra de la masculinidad tradicional, pero que ofrece una ventana de cambio de la masculinidad hegem?nica que es fuertemente mantenida en la sociedad. En este contexto, es importante que los profesionales de salud, se conviertan en agentes de cambio e promuevan partos m?s humanizados e acogedores, considerando como punto clave la perspectiva de g?nero en este proceso, as? como en la salud sexual y reproductiva en general