Electronic damage in quartz (c-SiO2) by MeV ion irradiations: Potentiality for optical waveguiding applications

The damage induced on quartz (c-SiO2) by heavy ions (F, O, Br) at MeV energies, where electronic stopping is dominant, has been investigated by RBS/C and optical methods. The two techniques indicate the formation of amorphous layers with an isotropic refractive index (n = 1.475) at fluences around 1014 cm−2 that are associated to electronic mechanisms. The kinetics of the process can be described as the superposition of linear (possibly initial Poisson curve) and sigmoidal (Avrami-type) contributions. The coexistence of the two kinetic regimes may be associated to the differential roles of the amorphous track cores and preamorphous halos. By using ions and energies whose maximum stopping power lies inside the crystal (O at 13 MeV, F at 15 MeV and F at 30 MeV) buried amorphous layer are formed and optical waveguides at the sample surface have been generated

Quality of sleep and academic performance in high school students

Indexación: Scopus.Background: Sleeping and studying are the day-to-day activities of a teenager attending school. Aim: To determine the quality of sleep and its relationship to the academic performance among students attending morning and afternoon shifts in a public high school. Material and Methods: Students of the first and second year of high school answered an interview about socio-demographic background, academic performance, student activities and subjective sleep quality; they were evaluated using the Pittsburgh Sleep Quality Index (PSQI). Results: The interview was answered by 322 first year students aged 15 ± 5 years attending the morning shift and 364 second year students, aged 16 ± 0.5 years, attending the afternoon shift. The components: sleep latency, habitual sleep efficiency, sleep disturbance, drug use and daytime dysfunction were similar and classified as good in both school shifts. The components subjective sleep quality and duration of sleep had higher scores among students of the morning shift. The mean grades during the first semester of the students attending morning and afternoon shifts were 5.9 and 5.8, respectively (of a scale from 1 to 7). Among students of both shifts, the PSQI scale was associated inversely and significantly with academic performance. Conclusions: A bad sleep quality influences academic performance in these students.https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0034-98872017000901106&lng=en&nrm=iso&tlng=e

Burnout Syndrome in Chilean Midwifery Students

Indexación: Scopus.The student Burnout Syndrome is a response to chronic and severe stress linked to the role of the students and their academic context. This study aims at determining the prevalence and severity of the student Burnout Syndrome on a sample of midwifery students and its associated factors. The study is observational, cross-sectional, and analytical, with a sample of 140 students of a Chilean university. The study variables were as follows: sociodemographic background, academic profile, student Burnout Syndrome scale, and behaviors in everyday psychosocial activities. The instrument for measuring the Burnout Syndrome was the Unidimensional Scale of Student Burnout. For the analysis, descriptive statistics were used, and the association of the independent over the dependent variables was assessed through linear regression. Of the third-year students, 77.2% had a moderate or deep burnout level, which increases to 91.8% in the fourth-year students. A significant and direct association was found between the syndrome and the career year. A significant association was also found between the Burnout Scale and the scale of psychosocial risk behavior. All the students present some degree of Burnout Syndrome, which is related to both their studies and psychosocial risks.https://journals.sagepub.com/doi/full/10.1177/215824402090209

Swift heavy ion damage to sodium chloride: synergy between excitation and thermal spikes

Systematic data on the effect of irradiation with swift ions (Zn at 735 MeV and Xe at 929 MeV) on NaCl single crystals have been analysed in terms of a synergetic two-spike approach (thermal and excitation spikes). The coupling of the two spikes, simultaneously generated by the irradiation, contributes to the operation of a non-radiative exciton decay model as proposed for purely ionization damage. Using this scheme, we have accounted for the π-emission yield of self-trapped excitons and its temperature dependence under ion-beam irradiation. Moreover, the initial production rates of F-centre growth have also been reasonably simulated for irradiation at low temperatures ( < 100 K), where colour centre annealing and aggregation can be neglected

Ingested insecticide to control Aedes aegypti: developing a novel dried attractive toxic sugar bait device for intra-domiciliary control

© 2020 The Author(s). Background: Illnesses transmitted by Aedes aegypti (Linnaeus, 1762) such as dengue, chikungunya and Zika comprise a considerable global burden; mosquito control is the primary public health tool to reduce disease transmission. Current interventions are inadequate and insecticide resistance threatens the effectiveness of these options. Dried attractive bait stations (DABS) are a novel mechanism to deliver insecticide to Ae. aegypti. The DABS are a high-contrast 28 inch2 surface coated with dried sugar-boric acid solution. Aedes aegypti are attracted to DABS by visual cues only, and the dried sugar solution elicits an ingestion response from Ae. aegypti landing on the surface. The study presents the development of the DABS and tests of their impact on Ae. aegypti mortality in the laboratory and a series of semi-field trials. Methods: We conducted multiple series of laboratory and semi-field trials to assess the survivability of Ae. aegypti mosquitoes exposed to the DABS. In the laboratory experiments, we assessed the lethality, the killing mechanism, and the shelf life of the device through controlled experiments. In the semi-field trials, we released laboratory-reared female Ae. aegypti into experimental houses typical of peri-urban tropical communities in South America in three trial series with six replicates each. Laboratory experiments were conducted in Quito, Ecuador, and semi-field experiments were conducted in Machala, Ecuador, an area with abundant wild populations of Ae. aegypti and endemic arboviral transmission. Results: In the laboratory, complete lethality was observed after 48 hours regardless of physiological status of the mosquito. The killing mechanism was determined to be through ingestion, as the boric acid disrupted the gut of the mosquito. In experimental houses, total mosquito mortality was greater in the treatment house for all series of experiments (P \u3c 0.0001). Conclusions: The DABS devices were effective at killing female Ae. aegypti under a variety of laboratory and semi-field conditions. DABS are a promising intervention for interdomiciliary control of Ae. aegypti and arboviral disease prevention.[Figure not available: see fulltext.

Diagnóstico del sector farmacéutico colombiano periodo 2000-2008

El grupo de investigación en perdurabilidad empresarial de la Facultad de Administración de la Universidad del Rosario tiene como propósito monitorear, investigar y difundir estudios que permitan generar conocimiento acerca de la perdurabilidad empresarial Colombiana. El tema de la permanencia de las empresas en el mercado es un asunto de preocupación, por los directores de empresas, que observan cómo discontinuidades presentes ponen a prueba su capacidad gerencial

Stopping power dependence of nitrogen sputtering yields in copper nitride films under swift-ion irradiation: Exciton model approach

Nitrogen sputtering yields as high as 104 atoms/ion, are obtained by irradiating N-rich-Cu3N films (N concentration: 33 ± 2 at.%) with Cu ions at energies in the range 10?42 MeV. The kinetics of N sputtering as a function of ion fluence is determined at several energies (stopping powers) for films deposited on both, glass and silicon substrates. The kinetic curves show that the amount of nitrogen release strongly increases with rising irradiation fluence up to reaching a saturation level at a low remaining nitrogen fraction (5?10%), in which no further nitrogen reduction is observed. The sputtering rate for nitrogen depletion is found to be independent of the substrate and to linearly increase with electronic stopping power (Se). A stopping power (Sth) threshold of ?3.5 keV/nm for nitrogen depletion has been estimated from extrapolation of the data. Experimental kinetic data have been analyzed within a bulk molecular recombination model. The microscopic mechanisms of the nitrogen depletion process are discussed in terms of a non-radiative exciton decay model. In particular, the estimated threshold is related to a minimum exciton density which is required to achieve efficient sputtering rates

Kinetics of color center formation in silica irradiated with swift heavy ions: Thresholding and formation efficiency

We have determined the cross-section σ for color center generation under single Br ion impacts on amorphous SiO2. The evolution of the cross-sections, σ(E) and σ(Se), show an initial flat stage that we associate to atomic collision mechanisms. Above a certain threshold value (Se > 2 keV/nm), roughly coinciding with that reported for the onset of macroscopic disorder (compaction), σ shows a marked increase due to electronic processes. In this regime, a energetic cost of around 7.5 keV is necessary to create a non bridging oxygen hole center-E′ (NBOHC/E′) pair, whatever the input energy. The data appear consistent with a non-radiative decay of self-trapped excitons

The effects of an appropriate behavior program on elementary school children social skills development in physical education

The purpose of this study was to see the effects of an appropriate behavior development program in relation to the improvement of fair play and social skills behaviors of elementary school children during the physical education class. The participants of this study were 204 students from 5th and 6th grade from seven different public schools in Castilla-La Mancha, Spain. Data was collected through a questionnaire to measure students' pre and post appropriate behaviors when winning, appropriate behaviors when loosing, appropriate behaviors during the game, fair play skills and social skills, during the physical education class. Results from this study revealed that participants improved their behaviors with the implementation of the intervention (appropriate behavior program), generating positive changes in students? attitudes and social skills during physical education class. In relation to children gender, girls had better scores than boys in relation to appropriate behaviors when losing. Further, when comparing students' age, those from 10 to 11 years old scored higher in fair play behaviors and social skills. In conclusion, the intervention program was effective to improve the behaviors of the school children, generating positive changes in their attitudes and social skills during physical education.Fil: Gil Madrona, Pedro. Universidad de Castilla-La Mancha; EspañaFil: Gutiérrez Marín, Eva Cristina. Universidad de Castilla-La Mancha; EspañaFil: Cupani, Marcos. Universidad Nacional de Córdoba. Instituto de Investigaciones Psicológicas. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Psicológicas; ArgentinaFil: Samalot Rivera, Amaury. State University of New York; Estados UnidosFil: Díaz Suárez, Arturo. Universidad de Murcia; EspañaFil: López Sánchez, Guillermo F.. Universidad de Murcia; Españ