The effects of lengthening the school day on female labor supply: Evidence from a quasi-experiment in Chile

In 1996, the Chilean government approved the extension of the school day, increasing the amount of time that students spend at school by 30%. Using data from the Chilean socio- economic household survey and administrative data from the Ministry of Education for 1990- 2006, we exploit the quasi-experimental nature of the reform’s implementation by time and region in order to identify the causal impact of the program on labor participation, employment and hours worked for women between 20 and 65 years old. The identification strategy relies on a fixed effect model of repeated cross-section. The results show a positive and significant effect on labor participation and female employment in all age groups and a negative and statistically significant effect on the number of hours worked. The main conclusion of this study is that the implicit childcare subsidy induced by the program had a positive and significant impact on the labor supply of women in Chile.Female labor supply; childcare; fertility; labor supply; Chile.

Sample size determination for estimating antibody seroconversion rate under stable malaria transmission intensity

Background In the last decade, several epidemiological studies have demonstrated the potential of using seroprevalence (SP) and seroconversion rate (SCR) as informative indicators of malaria burden in low transmission settings or in populations on the cusp of elimination. However, most of studies are designed to control ensuing statistical inference over parasite rates and not on these alternative malaria burden measures. SP is in essence a proportion and, thus, many methods exist for the respective sample size determination. In contrast, designing a study where SCR is the primary endpoint, is not an easy task because precision and statistical power are affected by the age distribution of a given population. Methods Two sample size calculators for SCR estimation are proposed. The first one consists of transforming the confidence interval for SP into the corresponding one for SCR given a known seroreversion rate (SRR). The second calculator extends the previous one to the most common situation where SRR is unknown. In this situation, data simulation was used together with linear regression in order to study the expected relationship between sample size and precision. Results The performance of the first sample size calculator was studied in terms of the coverage of the confidence intervals for SCR. The results pointed out to eventual problems of under or over coverage for sample sizes ≤250 in very low and high malaria transmission settings (SCR ≤ 0.0036 and SCR ≥ 0.29, respectively). The correct coverage was obtained for the remaining transmission intensities with sample sizes ≥ 50. Sample size determination was then carried out for cross-sectional surveys using realistic SCRs from past sero-epidemiological studies and typical age distributions from African and non-African populations. For SCR < 0.058, African studies require a larger sample size than their non-African counterparts in order to obtain the same precision. The opposite happens for the remaining transmission intensities. With respect to the second sample size calculator, simulation unravelled the likelihood of not having enough information to estimate SRR in low transmission settings (SCR ≤ 0.0108). In that case, the respective estimates tend to underestimate the true SCR. This problem is minimized by sample sizes of no less than 500 individuals. The sample sizes determined by this second method highlighted the prior expectation that, when SRR is not known, sample sizes are increased in relation to the situation of a known SRR. In contrast to the first sample size calculation, African studies would now require lesser individuals than their counterparts conducted elsewhere, irrespective of the transmission intensity. Conclusions Although the proposed sample size calculators can be instrumental to design future cross-sectional surveys, the choice of a particular sample size must be seen as a much broader exercise that involves weighting statistical precision with ethical issues, available human and economic resources, and possible time constraints. Moreover, if the sample size determination is carried out on varying transmission intensities, as done here, the respective sample sizes can also be used in studies comparing sites with different malaria transmission intensities. In conclusion, the proposed sample size calculators are a step towards the design of better sero-epidemiological studies. Their basic ideas show promise to be applied to the planning of alternative sampling schemes that may target or oversample specific age groups

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

Farmers’ perceptions towards production of Ojinegra lamb meat, an autochthonous sheep breed

Over the last two decades, in Spain there has been a growing interest in recovering and maintaining autochthonous livestock breeds. This has partly occurred because these breeds are considered essential to coping with changing socio-economic and environmental conditions. The aim of the present work is to analyze the perceptions of the farmers toward the production lamb meat from an autochthonous livestock breed in Spain. In addition, were explored the interrelationships between these perceptions and characteristics of farms as well as the farmers’ objectives. The information used was obtained from a sample of 34 lamb meat producers of an autochthone sheep breed originally from northeastern Spain. The statistical analysis performed was descriptive analysis, factor analysis and cluster analysis. The results show that breeders greatly value the positive effects of sheep breeding on rural development, which generate employment in disadvantaged areas. The cluster analysis reveals the existence of two groups of farmers with different perceptions. Moreover, results indicate that the positive perceptions of producers toward autochthonous breeds are closely related to the farmers’ objectives. Hence, public and private organization initiatives that seek to promote the development of a particular breed should account for livestock farm heterogeneity. En las dos últimas décadas se ha producido en España un creciente interés por recuperar y mantener razas de ganado autóctonas, en parte por considerarse esenciales en la adaptación a condiciones socio-económicas y ambientales cambiantes. El objetivo del trabajo es analizar las percepciones de un grupo de productores hacia la carne de cordero de una raza autóctona, relacionándolas con diferentes objetivos de los ganaderos y con características de sus explotaciones. La información empleada en el estudio se obtuvo a partir de entrevistas personales dirigidas a una muestra de 34 productores de ovino de la raza autóctona originaria del noreste de España. El análisis estadístico consistió en análisis descriptivo, factorial y cluster. Los resultados indican que los ganaderos valoran mucho el efecto positivo de la explotación de la raza sobre el desarrollo rural y la generación de empleo en zonas desfavorecidas. La segmentación realizada muestra la existencia de dos grupos de productores con percepciones diferentes hacia la raza. Además las percepciones positivas de los ganaderos hacia la raza autóctona, están muy relacionadas con los objetivos perseguidos por los ganaderos en su explotación. Es por ello que cualquier medida tomada por organizaciones públicas ó privadas que pretenda la promoción y fomento de una raza, debería tener en cuenta la heterogeneidad de las explotaciones

Milk consumption after exercise decreases electrolyte excretion.

La rehidratación es fundamental para la correcta recuperación posterior al ejercicio físico y el deporte. Las bebidas lácteas parecen ser una buena opción como bebidas rehidratantes después del ejercicio, pero aún los mecanismos no están completamente dilucidados. El presente estudio tiene por objetivo medir los efectos en la excreción de electrolitos en la orina al rehidratar con una bebida láctea baja en grasa o una bebida isotónica tras la realización de una sesión de ejercicio intermitente. 14 sujetos físicamente activos (23 ± 4 años), se dividieron en dos grupos: 1) rehidratación con bebida isotónica (ISO) y 2) rehidratación con bebida láctea baja en grasa (LBG). Se evaluó la gravedad específica de la orina (GEO), electrolitos (Na+ y K+) en orina y retención de fluidos, después del ejercicio y 4 horas posterior a la rehidratación. Se encontraron diferencias significativas en la GEO y en la excreción de K+ en el grupo LBG (p<0.005), ambos grupos muestran diferencias significativas en la excreción de Na+. Los resultados muestran que la rehidratación con bebida láctea mejora la GEO y disminuyen la excreción de K+ de forma más eficiente que la bebida isotónica posterior al ejercicioRehydration is essential for post-exercise and sport recovery. Milk seems to be a good option like sport drinks after exercise, yet the rehydration mechanisms are still not fully understood. The aim of this study was to measure the effect of drinking low-fat milk and an isotonic beverage after intermittent exercise on urine electrolytes. 14 physically active men (23 ± 4 y) were split into two groups: 1) rehydration with isotonic drink (ISO), and 2) rehydration with low-fat milk (LBG). Specific gravity (GEO) and electrolytes (Na+ and K+) were measured in urine before and after exercise with rehydration. Significant differences were found for the GEO and in K+ excretion in the LBG group (p <0.05). Both groups showed significant differences for Na+ excretion concentrations. We conclude that drinking low fat milk after exercise when compared to an isotonic drink, improves GEO and K excretio

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