Semiclassical propagator of the Wigner function

Propagation of the Wigner function is studied on two levels of semiclassical propagation, one based on the van-Vleck propagator, the other on phase-space path integration. Leading quantum corrections to the classical Liouville propagator take the form of a time-dependent quantum spot. Its oscillatory structure depends on whether the underlying classical flow is elliptic or hyperbolic. It can be interpreted as the result of interference of a \emph{pair} of classical trajectories, indicating how quantum coherences are to be propagated semiclassically in phase space. The phase-space path-integral approach allows for a finer resolution of the quantum spot in terms of Airy functions.Comment: 4 pages, 3 figure

Transparent conducting oxides for active hybrid metamaterial devices

We present here a study of the combined nonlinear response of plasmonic antenna—transparent conducting oxide hybrids for activation of metamaterial devices. Nanoantenna layers consisting of randomly positioned gold nanodisk dimers are fabricated using hole-mask lithography. The nanoantenna layers are covered with a 20 nm thin layer of transparent conducting oxide (TCO). We investigate the response of atomic layer deposited aluminum-doped zinc oxide (AZO) next to indium–tin oxide (ITO) produced using sputter coating. We show that our results are in agreement with the hypothesis of fast electron-mediated cooling, facilitated by the Ohmic interface between the gold nanodisks and the TCO substrate, which appears a universal mechanism for providing a new hybrid functionality to active metamaterial device

Sharp values for the constants in the polynomial Bohnenblust-Hille inequality

In this paper we prove that the complex polynomial Bohnenblust-Hille constant for $2$-homogeneous polynomials in ${\mathbb C}^2$ is exactly $\sqrt[4]{\frac{3}{2}}$. We also give the exact value of the real polynomial Bohnenblust-Hille constant for $2$-homogeneous polynomials in ${\mathbb R}^2$. Finally, we provide lower estimates for the real polynomial Bohnenblust-Hille constant for polynomials in ${\mathbb R}^2$ of higher degrees.Comment: 16 page

Reproductive capacity of the red cusk-eel genypterus chilensis (Guichenot, 1848) in captivity

Indexación: Scopus.This work was supported by the FONDEF Project D06I 1024 “Development of technologies for the production of red cusk-eel fingerlings (Genypterus chilensis)”.Genypterus chilensis is a marine fish of high gastronomic demand, whose capture has declined in recent years due to overfishing. In the development of the farming technology, high mortalities were obtained during egg incubation. The objective of this study is to contribute to the knowledge of fecundity and eggs viability of G. chilensis in captivity. The spawns of G. chilensis were analyzed over a period of 2 years and 3 months. The total fecundity was estimated by counting the masses and eggs produced monthly throughout the period. The results confirm that G. chilensis is a partial spawner, since a female may more than two masses of eggs per day, due to a large amount of mass spawned per season (621 average). The total production of masses of the Farming Centre during the period was 2,290; of these, only 7% (166) corresponding to 15,330,517 eggs were incubated. Because of its high fecundity, G. chilensis produces numerous masses of eggs, of which only a small percentage reaches incubation, as well as it occurs in other marine fish. © 2018, Escuela de Ciencias del Mar. All rights reserved.https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-560X201800020048

Dynamics of glass-forming liquids. XVI. Observation of ultrastable glass transformation via dielectric spectroscopy

The transformation of vapor-deposited ultrastable glasses of indomethacin (IMC) into the supercooled liquid state near Tg is monitored by means of dielectric spectroscopy. Films with thickness between 400 and 800 nm are deposited on differential interdigitated electrode cells and their loss profiles are measured during isothermal annealing using a dual-channel impedance technique for frequencies between 0.03 and 100 Hz. All dielectric loss spectra observed during the transformation process can be explained by a volume fraction of the supercooled liquid that increases linearly with time. From the early stages of the transformation to the liquid that is formed via complete annealing of the ultrastable glass, the average dielectric relaxation time as well as the distribution of relaxation times of the liquid component are identical to those of the conventional liquid obtained by cooling the melt. The dependence of the transformation rate on the film thickness is consistent with a growth front mechanism for the direct conversion from the ultrastable glass to the equilibrium supercooled liquid. We conclude that the IMC liquid recovered from the ultrastable glass is structurally and dynamically identical to the conventional supercooled state

Single-site port robotic-assisted simple nephrectomy (LESS)

Indexación: Web of Science; ScieloIntroduction: Minimally invasive surgery in urology is rapidly advancing and Laparo-endoscopic single-site surgery (LESS) is not the exception. Such laparoscopic procedures are technically challenging and require an experienced laparoscopic surgeon due to the lack of port placement triangulation and instrument clashing. The benefit of the da Vinci surgical system has recently introduced to LESS. We present two cases of robotic LESS nephrectomy. Matherials and Methods: Two patients, a female of 23 years old, diagnosed with right renal atrophy secondary to chronic pyelonephritis and one male patient with diagnosis of left staghorn calculi and renal atrophy. Both underwent to a total nephrectomy assisted by the da Vinci S surgical system through a single port incision using the GelPoint® access system. Results: The first surgery was performed without incidents or conversion. The second patient required the installation of an additional robotic port for triangulation. The dock time and the mean operative time was 18 and 110 min. The mean estimated blood loss was 100 cc and the hospital stay was 27 hours. There were no complications. Conclusions: LESS robotic surgery is feasible using current robotic systems. However, there are several limitations. The design of specific technology for the use of the robot through single incision can solve this problem.Introducción: La cirugía mínimamente invasiva en urología avanza rápidamente y la cirugía laparo-endoscópica a través de puerto único (LESS) no es la excepción. Esta técnica por vía laparoscópica presenta mucha dificultad y requiere de un cirujano laparoscópico experimentado debido a la falta de triangulación y el cruce de los instrumentos. Los beneficios del sistema quirúrgico da Vinci® han sido introducidos recientemente en LESS. Presentamos dos casos de nefrectomía LESS asistida por robot. Materiales y Métodos: Dos pacientes, la primera de sexo femenino y 23 años de edad, con diagnóstico de atrofia renal secundaria a pielonefritis crónica derecha y un segundo paciente de sexo masculino con diagnóstico de litiasis coraliforme izquierda y atrofia renal. Ambos pacientes fueron sometidos a una nefrectomía total asistida por el sistema quirúrgico robótico da Vinci S a través de un puerto único utilizando el dispositivo de acceso GelPoint®. Resultados: La primera cirugía fue llevada a cabo sin incidentes, sin necesidad de conversión. En el segundo paciente fue necesaria la instalación de un puerto robótico adicional para triangulación. El tiempo de acoplamiento y operatorio promedio fue de 18 y 110 min. El sangrado promedio estimado fue de 100 cc y la estadía hospitalaria promedio de 27 horas. No hubo complicaciones. Conclusiones: La cirugía robótica LESS es posible de realizar utilizando los sistemas robóticos actuales. Sin embargo, existen diversas limitaciones. El diseño de tecnología específica para el uso del robot por puerto único podrá solucionar este problema.http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-40262011000500011&nrm=is

Burnout syndrome prevalence in veterinarians working in Chile

Burnout Syndrome is a psycho-emotional syndrome that affects workers in any activity or profession. In recent years, veterinarians have been described as one of the most affected professionals, which has motivated the development of this research. The primary objective of this work was to determine the prevalence of Burnout Syndrome in veterinarians working in Chile. We evaluated the possible correlation of Burnout Syndrome with socio-demographic variables. The Socio-Demographic Characterization Survey and the Maslach Burnout Syndrome Inventory-General Survey (MBI) were applied to 521 participants, who were contacted through the Veterinary Medical Association of Chile (COLMEVET) and social networks. Fisher and Chi-square statistical tests and correspondence analysis were used to determine the association among variables. The prevalence of Burnout Syndrome in Chilean veterinarians was 24% (124/521). There was statistical significance between Burnout Syndrome and the variables ‘years in employment’ and ‘monthly salary’. There is a high prevalence of Burnout Syndrome in veterinarians working in Chile that was related to the variables ‘years in employment’ and ‘monthly salary’. Prevention using psychological therapy could reduce the incidence of symptoms linked to adaptive difficulties, cognitive discrepancies, psychological discomfort, and emotional regulation, promoting health improvement and resistance to Burnout Syndrome in Chilean veterinarians. This research corresponds to the first exploratory study related to the subject in Chil

uma proposta de investigação

UIDB/05021/2020 UIDP/05021/2020A tecnologia confere potencial no âmbito educacional seja como meio, constituindo um veículo para a aprendizagem, ou como ferramenta, através da qual são disponibilizados conteúdos. É assim natural que, com a presença e o acesso mais amplo à tecnologia, o contexto educacional e as suas dimensões se vão transformando. Numa sociedade na qual um conjunto de atividades diárias são realizadas com recurso à tecnologia e à internet, aquelas que estão relacionadas com a educação não serão exceção, não sendo também exceção que expressões destas transformações sejam partilhadas nos media sociais. As plataformas digitais, nomeadamente os media sociais, têm constituído uma camada comunicacional através da qual reflexos de transformações e de dinâmicas são escutados, lidos, visualizados e passíveis de serem medidos. A tecnologia no contexto educacional é encarada como um possível objeto de estudo. Mais, o recurso à tecnologia para o investigar, surge como uma oportunidade para compreender o potencial e o alcance de novas soluções metodológicas. Neste capítulo, tomámos como objeto empírico o programa do Ministério da Educação português #EstudoEmCasa, lançado em 2020 como resposta à condição pandémica e à suspensão das aulas presenciais. Para compreender de que forma o #EstudoEmCasa é discutido e apropriado nas plataformas sociais, reunimos um conjunto de dados extraídos do Instagram, Twitter e YouTube. Os principais resultados apontam para uma resposta em paralelo às aulas televisionadas, numa espécie de segundo ecrã que gera debate em torno das temáticas, qualidade das aulas, descontextualização, humor e “memetização” do conteúdo do programa, mas também onde se partilham ambientes de estudo e os seus constituintes.publishersversionpublishe

Reacción del precio de las acciones a los cambios de estructura de capital en empresas chilenas: Examinando los efectos de la estructura de propiedad, oportunidades de crecimiento y leverage

We analyzed the effects of ownership structure, capital structure and growth opportunities on stock price reactions when companies issued debt or equity. Our results, based on event study methodology and IV regressions from a sample of 70 Chilean firms, indicate that controlling shareholder ownership has a negative effect on stock price reactions for debt issuances and a positive effect for equity issuance. These results indicate that debt issuances are a substitute for majority shareholder monitoring, and that equity issuances are associated with superior corporate performance. Equity issuances are a means for expropriating wealth from non-controlling shareholders. Debt and growth opportunities have a non-linear effect.En este artículo analizamos los efectos de la estructura de propiedad, estructura de capital y las oportunidades de crecimiento sobre la reacción del precio de las acciones cuando las empresas emiten deuda o capital. Nuestros resultados, basados en la metodología de análisis de eventos y regresiones IV sobre una muestra de 70 empresas chilenas, indican que la propiedad de los accionistas controladores tiene un efecto negativo en la reacción del precio de las acciones cuando las empresas emiten deuda y positivo cuando emiten acciones. Este resultado indica que las emisiones de deuda son un sustituto del control mayoritario de los accionistas y las emisiones de capital se asocian con un mayor desempeño corporativo. Las emisiones de capital son un medio para expropiar riqueza de los accionistas no controladores. Las oportunidades de deuda y crecimiento tienen un efecto no lineal

Reacción del precio de las acciones a los cambios de estructura de capital en empresas chilenas: Examinando los efectos de la estructura de propiedad, oportunidades de crecimiento y leverage

We analyzed the effects of ownership structure, capital structure and growth opportunities on stock price reactions when companies issued debt or equity.Our results, based on event study methodology and IV regressions from a sample of 70 Chilean firms, indicate that controlling shareholder ownership has a negative effect on stock price reactions for debt issuances and a positive effect for equity issuance. These results indicate that debt issuances are a substitute for majority shareholder monitoring, and that equity issuances are associated with superior corporate performance. Equity issuances are a means for expropriating wealth from non-controlling shareholders. Debt and growth opportunities have a non-linear effect.En este artículo analizamos los efectos de la estructura de propiedad, estructura de capital y las oportunidades de crecimiento sobre la reacción del precio delas acciones cuando las empresas emiten deuda o capital. Nuestros resultados, basados en la metodología de análisis de eventos y regresiones IV sobre unamuestra de 70 empresas chilenas, indican que la propiedad de los accionistas controladores tiene un efecto negativo en la reacción del precio de las acciones cuando las empresas emiten deuda y positivo cuando emiten acciones. Este resultado indica que las emisiones de deuda son un sustituto del control mayoritario de los accionistas y las emisiones de capital se asocian con un mayor desempeño corporativo. Las emisiones de capital son un medio para expropiar riqueza de los accionistas no controladores. Las oportunidades de deuda y crecimiento tienen un efecto no lineal