El transporte terrestre

La actividad económica exige, para su eficiente desarrollo una infraestructura compleja cuyos componentes se hallan íntimamente relacionados entre sí. Los transportes, las comunicaciones, la energía y otros servicios y factores no menos esenciales, se han transformado, por esta razón, en motivo de constante preocupación dentro de lo que se refiere a la planificación. En los países en desarrollo, la carencia de una infraestructura idónea multiplica las dificultades que se debe afrontar para terminar con el estancamiento o aumentar el ritmo de crecimiento económico. En el Ecuador, como en todo país subdesarrollado, los problemas del transporte son especialmente graves, razón por la cual se ha considerado importante desarrollar un trabajo sobre el transporte terrestre

Prediseño y simulación de un sistema de inyección directa para un motor de combustión interna de dos tiempos

El presente artículo describe el procedimiento desarrollado para alcanzar una solución al problema del corto circuito de la mezcla fresca hacia el puerto de escape en los motores de combustión interna de dos tiempos. Se diseñó un sistema de inyección directa para este tipo de motores, el cual permite regular la composición de la mezcla aire-combustible y el momento del ingreso del combustible al cilindro. El diseño alcanzado elimina el problema y de esta forma posibilita una reducción en las emisiones contaminantes. Los parámetros iniciales como presiones, temperaturas y caudales en el motor, fueron determinados por medio de una simulación computacional empleando un modelo de flujo inestable unidimensional denominado GPB

Prediseño y simulación de un sistema de inyección directa para un motor de combustión interna de dos tiempos

El presente artículo describe el procedimiento desarrollado para alcanzar una solución al problema del corto circuito de la mezcla fresca hacia el puerto de escape en los motores de combustión interna de dos tiempos. Se diseñó un sistema de inyección directa para este tipo de motores, el cual permite regular la composición de la mezcla aire-combustible y el momento del ingreso del combustible al cilindro. El diseño alcanzado elimina el problema y de esta forma posibilita una reducción en las emisiones contaminantes. Los parámetros iniciales como presiones, temperaturas y caudales en el motor, fueron determinados por medio de una simulación computacional empleando un modelo de flujo inestable unidimensional denominado GPB

Shifts in food webs and niche stability shaped survivorship and extinction at the end-Cretaceous

It has long been debated why groups such as non-avian dinosaurs became extinct whereas mammals and other lineages survived the Cretaceous/Paleogene mass extinction 66 million years ago. We used Markov networks, ecological niche partitioning, and Earth System models to reconstruct North American food webs and simulate ecospace occupancy before and after the extinction event. We find a shift in latest Cretaceous dinosaur faunas, as medium-sized species counterbalanced a loss of megaherbivores, but dinosaur niches were otherwise stable and static, potentially contributing to their demise. Smaller vertebrates, including mammals, followed a consistent trajectory of increasing trophic impact and relaxation of niche limits beginning in the latest Cretaceous and continuing after the mass extinction. Mammals did not simply proliferate after the extinction event; rather, their earlier ecological diversification might have helped them survive

Seroprevalencia del virus de Lengua Azul en cabras (Capra hircus) de la Región Norte del Perú

Bluetongue is an endemic disease in tropical and subtropical regions and the virus that causes the disease is transmitted by mosquito vectors of the genus Culicoides. The aim of this study was to determine the seroprevalence of the Bluetongue virus (BTV) in goats from the departments of Tumbes, Piura, Lambayeque, Cajamarca and La Libertad (Peru). Blood samples (n=424) were collected from goats older than 6 months of age, without clinical signs of disease and reared in extensive production systems between June and October 2017. The sera were analysed with commercial ELISA competition kits to determine antibodies against BTV. A seroprevalence of 23.8% (95% CI 19.84-28.16) was found. The results by department indicate that 34.9% (81/232), 20.9% (13/62), 9.5% (4/42) and 6.0% (3/50) and 0% (0/38) of samples from Piura, Tumbes, Cajamarca. Lambayeque and La Libertad, respectively, had antibodies against BTV. The seropositivity showed a positive association (p<0.05) with the age of the goats and negative (p<0.05) with the altitude of rearing.Lengua Azul es una enfermedad endémica en regiones tropicales y subtropicales y el virus causante de la enfermedad es transmitido por mosquitos vectores del género Culicoides. El objetivo del presente estudio fue determinar la seroprevalencia del virus de Lengua azul (VLA) en cabras de los departamentos de Tumbes, Piura, Lambayeque, Cajamarca y La Libertad (Perú). Se colectaron muestras de sangre (n=424) entre junio a octubre de 2017 de cabras mayores a 6 meses de edad, sin signos clínicos de enfermedad y criadas en forma extensiva. Los sueros fueron analizados con kits comerciales de ELISA de competición para determinar anticuerpos contra VLA. Se encontró una seroprevalencia de 23.8% (IC 95% 19.84-28.16). Los resultados por departamento indican que 34.9% (81/232), 20.9% (13/62), 9.5% (4/42) y 6.0% (3/50) y 0% (0/38) de las cabras de Piura, Tumbes, Cajamarca. Lambayeque y La Libertad, respectivamente, tuvieron anticuerpos contra el VLA. La seropositividad al VLA mostró una asociación positiva (p<0.05) con la edad de las cabras y negativa (p<0.05) con la altitud (msnm) de crianza

Seroprevalencia del Virus de la Rinoneumonitis en Caballos (Equus caballus) del Perú

The aim of this study was to determine the seroprevalence of antibodies against Equine Herpes Virus type 1 (EHV-1) and Equine Herpes Virus type 4 (EHV-4), which causes rhinopneumonitis in horses. Blood samples (n=825) from Peruvian horses older than six months of age, both sexes, identified as racehorses, Peruvian Paso, equitation and criollo, in apparent healthy conditions, were collected for detection of neutralizing antibodies against EHV-1/EHV-4 by virus neutralization test. The 48.9 ± 5.3% (403/825) of the samples had antibodies against EHV-1/EHV-4. Antibody titers ranged from 2 to >256, where 58.5% ranged from 2 to 8, 29.5% from 16 to 64, and 11.9% from 128 to >256. The sex and region of the country did not represent a risk for presenting antibodies against EHV-1/EHV-4.El objetivo del presente estudio fue determinar la seroprevalencia del virus Herpes Equino tipo 1 o Herpes Equino tipo 4 (VHE-1/VHE-4), causante de la rinoneumonitis viral en caballos. Se recolectaron muestras de suero (n=825) de caballos mayores a seis meses de edad, entre machos y hembras, identificados como caballos de crianza familiar, de carrera, Peruano de Paso y de equitación, clínicamente normales, provenientes de varias regiones del Perú, para la detección de anticuerpos neutralizantes contra el VHE-1/VHE- 4 mediante la prueba de neutralización viral. El 48.9 ± 5.3% (403/825) de las muestras tuvieron anticuerpos contra el VHE-1/VHE-4. Los títulos de anticuerpos tuvieron un rango entre 2 a >256, siendo de 58.6% de títulos de 2 a 8, de 29.5% en títulos de 16 a 64, y de 11.9% en títulos de 128 a >256. La prueba de regresión logística indicó que las variables sexo y lugar de procedencia no constituyeron factores de riesgo para la presentación de anticuerpos contra el VHE-1/VHE-4

Magazine of the Faculty of Education. Volume 3 No. 4 May 1987

Con beneplácito entregamos en este cuarto número de la Revista de la Facultad de Educación Preescolar, el resultado de algunas de las actividades que nos hemos propuesto. En la sección Nuestra Facultad incluimos un resumen de la propuesta de rediseño curricular del Programa de Licenciatura en Educación Preescolar cuya implementación estamos iniciando, así como las colaboraciones de estudiantes y docentes.With pleasure we deliver in this fourth issue of the Magazine of the Faculty of Preschool Education, the result of some of the activities that we have proposed. In the Our Faculty section we include a summary of the proposal of curricular redesign of the Bachelor's Program in Preschool Education whose implementation we are beginning, as well as the collaborations of students and teachers.Modalidad Presencia

Global age-sex-specific fertility, mortality, healthy life expectancy (HALE), and population estimates in 204 countries and territories, 1950-2019 : a comprehensive demographic analysis for the Global Burden of Disease Study 2019

Background: Accurate and up-to-date assessment of demographic metrics is crucial for understanding a wide range of social, economic, and public health issues that affect populations worldwide. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 produced updated and comprehensive demographic assessments of the key indicators of fertility, mortality, migration, and population for 204 countries and territories and selected subnational locations from 1950 to 2019. Methods: 8078 country-years of vital registration and sample registration data, 938 surveys, 349 censuses, and 238 other sources were identified and used to estimate age-specific fertility. Spatiotemporal Gaussian process regression (ST-GPR) was used to generate age-specific fertility rates for 5-year age groups between ages 15 and 49 years. With extensions to age groups 10–14 and 50–54 years, the total fertility rate (TFR) was then aggregated using the estimated age-specific fertility between ages 10 and 54 years. 7417 sources were used for under-5 mortality estimation and 7355 for adult mortality. ST-GPR was used to synthesise data sources after correction for known biases. Adult mortality was measured as the probability of death between ages 15 and 60 years based on vital registration, sample registration, and sibling histories, and was also estimated using ST-GPR. HIV-free life tables were then estimated using estimates of under-5 and adult mortality rates using a relational model life table system created for GBD, which closely tracks observed age-specific mortality rates from complete vital registration when available. Independent estimates of HIV-specific mortality generated by an epidemiological analysis of HIV prevalence surveys and antenatal clinic serosurveillance and other sources were incorporated into the estimates in countries with large epidemics. Annual and single-year age estimates of net migration and population for each country and territory were generated using a Bayesian hierarchical cohort component model that analysed estimated age-specific fertility and mortality rates along with 1250 censuses and 747 population registry years. We classified location-years into seven categories on the basis of the natural rate of increase in population (calculated by subtracting the crude death rate from the crude birth rate) and the net migration rate. We computed healthy life expectancy (HALE) using years lived with disability (YLDs) per capita, life tables, and standard demographic methods. Uncertainty was propagated throughout the demographic estimation process, including fertility, mortality, and population, with 1000 draw-level estimates produced for each metric. Findings: The global TFR decreased from 2·72 (95% uncertainty interval [UI] 2·66–2·79) in 2000 to 2·31 (2·17–2·46) in 2019. Global annual livebirths increased from 134·5 million (131·5–137·8) in 2000 to a peak of 139·6 million (133·0–146·9) in 2016. Global livebirths then declined to 135·3 million (127·2–144·1) in 2019. Of the 204 countries and territories included in this study, in 2019, 102 had a TFR lower than 2·1, which is considered a good approximation of replacement-level fertility. All countries in sub-Saharan Africa had TFRs above replacement level in 2019 and accounted for 27·1% (95% UI 26·4–27·8) of global livebirths. Global life expectancy at birth increased from 67·2 years (95% UI 66·8–67·6) in 2000 to 73·5 years (72·8–74·3) in 2019. The total number of deaths increased from 50·7 million (49·5–51·9) in 2000 to 56·5 million (53·7–59·2) in 2019. Under-5 deaths declined from 9·6 million (9·1–10·3) in 2000 to 5·0 million (4·3–6·0) in 2019. Global population increased by 25·7%, from 6·2 billion (6·0–6·3) in 2000 to 7·7 billion (7·5–8·0) in 2019. In 2019, 34 countries had negative natural rates of increase; in 17 of these, the population declined because immigration was not sufficient to counteract the negative rate of decline. Globally, HALE increased from 58·6 years (56·1–60·8) in 2000 to 63·5 years (60·8–66·1) in 2019. HALE increased in 202 of 204 countries and territories between 2000 and 2019

Global, regional, and national disability-adjusted life-years (DALYs) for 359 diseases and injuries and healthy life expectancy (HALE) for 195 countries and territories, 1990-2017: a systematic analysis for the Global Burden of Disease Study 2017.

How long one lives, how many years of life are spent in good and poor health, and how the population's state of health and leading causes of disability change over time all have implications for policy, planning, and provision of services. We comparatively assessed the patterns and trends of healthy life expectancy (HALE), which quantifies the number of years of life expected to be lived in good health, and the complementary measure of disability-adjusted life-years (DALYs), a composite measure of disease burden capturing both premature mortality and prevalence and severity of ill health, for 359 diseases and injuries for 195 countries and territories over the past 28 years. Methods We used data for age-specific mortality rates, years of life lost (YLLs) due to premature mortality, and years lived with disability (YLDs) from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2017 to calculate HALE and DALYs from 1990 to 2017. We calculated HALE using age-specific mortality rates and YLDs per capita for each location, age, sex, and year. We calculated DALYs for 359 causes as the sum of YLLs and YLDs. We assessed how observed HALE and DALYs differed by country and sex from expected trends based on Socio-demographic Index (SDI). We also analysed HALE by decomposing years of life gained into years spent in good health and in poor health, between 1990 and 2017, and extra years lived by females compared with males. Findings Globally, from 1990 to 2017, life expectancy at birth increased by 7·4 years (95% uncertainty interval 7·1-7·8), from 65·6 years (65·3-65·8) in 1990 to 73·0 years (72·7-73·3) in 2017. The increase in years of life varied from 5·1 years (5·0-5·3) in high SDI countries to 12·0 years (11·3-12·8) in low SDI countries. Of the additional years of life expected at birth, 26·3% (20·1-33·1) were expected to be spent in poor health in high SDI countries compared with 11·7% (8·8-15·1) in low-middle SDI countries. HALE at birth increased by 6·3 years (5·9-6·7), from 57·0 years (54·6-59·1) in 1990 to 63·3 years (60·5-65·7) in 2017. The increase varied from 3·8 years (3·4-4·1) in high SDI countries to 10·5 years (9·8-11·2) in low SDI countries. Even larger variations in HALE than these were observed between countries, ranging from 1·0 year (0·4-1·7) in Saint Vincent and the Grenadines (62·4 years [59·9-64·7] in 1990 to 63·5 years [60·9-65·8] in 2017) to 23·7 years (21·9-25·6) in Eritrea (30·7 years [28·9-32·2] in 1990 to 54·4 years [51·5-57·1] in 2017). In most countries, the increase in HALE was smaller than the increase in overall life expectancy, indicating more years lived in poor health. In 180 of 195 countries and territories, females were expected to live longer than males in 2017, with extra years lived varying from 1·4 years (0·6-2·3) in Algeria to 11·9 years (10·9-12·9) in Ukraine. Of the extra years gained, the proportion spent in poor health varied largely across countries, with less than 20% of additional years spent in poor health in Bosnia and Herzegovina, Burundi, and Slovakia, whereas in Bahrain all the extra years were spent in poor health. In 2017, the highest estimate of HALE at birth was in Singapore for both females (75·8 years [72·4-78·7]) and males (72·6 years [69·8-75·0]) and the lowest estimates were in Central African Republic (47·0 years [43·7-50·2] for females and 42·8 years [40·1-45·6] for males). Globally, in 2017, the five leading causes of DALYs were neonatal disorders, ischaemic heart disease, stroke, lower respiratory infections, and chronic obstructive pulmonary disease. Between 1990 and 2017, age-standardised DALY rates decreased by 41·3% (38·8-43·5) for communicable diseases and by 49·8% (47·9-51·6) for neonatal disorders. For non-communicable diseases, global DALYs increased by 40·1% (36·8-43·0), although age-standardised DALY rates decreased by 18·1% (16·0-20·2)

Global burden of 369 diseases and injuries in 204 countries and territories, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019

Background: In an era of shifting global agendas and expanded emphasis on non-communicable diseases and injuries along with communicable diseases, sound evidence on trends by cause at the national level is essential. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) provides a systematic scientific assessment of published, publicly available, and contributed data on incidence, prevalence, and mortality for a mutually exclusive and collectively exhaustive list of diseases and injuries. Methods: GBD estimates incidence, prevalence, mortality, years of life lost (YLLs), years lived with disability (YLDs), and disability-adjusted life-years (DALYs) due to 369 diseases and injuries, for two sexes, and for 204 countries and territories. Input data were extracted from censuses, household surveys, civil registration and vital statistics, disease registries, health service use, air pollution monitors, satellite imaging, disease notifications, and other sources. Cause-specific death rates and cause fractions were calculated using the Cause of Death Ensemble model and spatiotemporal Gaussian process regression. Cause-specific deaths were adjusted to match the total all-cause deaths calculated as part of the GBD population, fertility, and mortality estimates. Deaths were multiplied by standard life expectancy at each age to calculate YLLs. A Bayesian meta-regression modelling tool, DisMod-MR 2.1, was used to ensure consistency between incidence, prevalence, remission, excess mortality, and cause-specific mortality for most causes. Prevalence estimates were multiplied by disability weights for mutually exclusive sequelae of diseases and injuries to calculate YLDs. We considered results in the context of the Socio-demographic Index (SDI), a composite indicator of income per capita, years of schooling, and fertility rate in females younger than 25 years. Uncertainty intervals (UIs) were generated for every metric using the 25th and 975th ordered 1000 draw values of the posterior distribution. Findings: Global health has steadily improved over the past 30 years as measured by age-standardised DALY rates. After taking into account population growth and ageing, the absolute number of DALYs has remained stable. Since 2010, the pace of decline in global age-standardised DALY rates has accelerated in age groups younger than 50 years compared with the 1990–2010 time period, with the greatest annualised rate of decline occurring in the 0–9-year age group. Six infectious diseases were among the top ten causes of DALYs in children younger than 10 years in 2019: lower respiratory infections (ranked second), diarrhoeal diseases (third), malaria (fifth), meningitis (sixth), whooping cough (ninth), and sexually transmitted infections (which, in this age group, is fully accounted for by congenital syphilis; ranked tenth). In adolescents aged 10–24 years, three injury causes were among the top causes of DALYs: road injuries (ranked first), self-harm (third), and interpersonal violence (fifth). Five of the causes that were in the top ten for ages 10–24 years were also in the top ten in the 25–49-year age group: road injuries (ranked first), HIV/AIDS (second), low back pain (fourth), headache disorders (fifth), and depressive disorders (sixth). In 2019, ischaemic heart disease and stroke were the top-ranked causes of DALYs in both the 50–74-year and 75-years-and-older age groups. Since 1990, there has been a marked shift towards a greater proportion of burden due to YLDs from non-communicable diseases and injuries. In 2019, there were 11 countries where non-communicable disease and injury YLDs constituted more than half of all disease burden. Decreases in age-standardised DALY rates have accelerated over the past decade in countries at the lower end of the SDI range, while improvements have started to stagnate or even reverse in countries with higher SDI. Interpretation: As disability becomes an increasingly large component of disease burden and a larger component of health expenditure, greater research and developm nt investment is needed to identify new, more effective intervention strategies. With a rapidly ageing global population, the demands on health services to deal with disabling outcomes, which increase with age, will require policy makers to anticipate these changes. The mix of universal and more geographically specific influences on health reinforces the need for regular reporting on population health in detail and by underlying cause to help decision makers to identify success stories of disease control to emulate, as well as opportunities to improve. Funding: Bill & Melinda Gates Foundation. © 2020 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 licens