Orbital decay in the classroom

The objective of this paper is to provide a pedagogical framework for the phenomenon of orbital decay of satellites in low Earth orbit. The dynamics of orbital decay are derived considering atmospheric drag as the only dissipative mechanism and using an educational approach suitable for undergraduate calculus-based physics and engineering courses. The resulting nonlinear first-order differential equation for the altitude as a function of time is solved numerically for the isothermal-barotropic atmospheric model with a fixed scale height. The model is validated using the uncontrolled reentry data of the Chinese space station Tiangong-1

Ocurrencia de cestodos anormales: hallazgo de Taenia multiceps trirradiado

Three atypical cestodes with abnormal morphology were found in a domestic dog. The cestodes had a scolex with six suction cups and a triradiate strobila. All parasites were gravid cestodes. In addition, the dog was infested with 324 normal cestodes. Both cestodes (normal and abnormal) were morphologically and molecularly identified as Taenia multiceps. The sequences of the cytochrome c oxidase subunit 1 gene of the triradiate cestode and normal cestodes were identical to each other and had more than 99% similarity with other published and recorded sequences for T. multiceps. These findings represent the first record of atypical cestodes and massive cestode infestation by T. multiceps in a dog from Peru.Tres cestodos atípicos con morfología anormal fueron hallados en un perro doméstico. Los cestodos tenían un escólex con seis ventosas y un estróbilo trirradiado. Todos los parásitos fueron cestodos grávidos. Además, el perro estaba infestado con 324 cestodos normales. Ambos cestodos (normales y anormales) fueron morfológica y molecularmente identificados como Taenia multiceps. Las secuencias del gen citocromo c oxidasa subunidad 1 del cestodo trirradiado y de los cestodos normales eran idénticas entre sí, y tenían más de 99% de similitud con otras secuencias publicadas y registradas para T. multiceps. Estos hallazgos representan el primer registro de cestodos atípicos e infestación masiva de cestodos por T. multiceps en un perro de Perú

Diagnóstico morfológico y molecular de Cyclocoelum mutabile (Trematoda: Cyclocoelidae) en el Perú

Cyclocoelum mutabile, un digeneo de la familia Cyclocoelidae, fue hallado parasitando los sacos aéreos de una polla de agua común (Gallinula chloropus), proveniente de alrededores del Refugio de Vida Silvestre Pantanos de villa, localizada en el distrito de Chorrillos en Lima, Perú. Un total de 7 parásitos fueron colectados e identificados por métodos morfológicos como C. mutabile. El diagnóstico fue confirmado por análisis molecular, amplificando los genes mitocondriales citocromo c oxidasa subunidad 1 (cox1) y deshidrogenasa NADH subunidad 1 (nad1). Las secuencias de nucleótidos de los aislados se compararon con secuencias previas de GenBank, y mostraron una similitud entre ellas (> 96%). Este hallazgo constituye el primer registro de C. mutabile para el Perú. Además, el trabajo realiza una breve descripción del parásito, así como la discusión de sus hospederos y distribución geográfica en Sudamérica

Morphological and molecular evidence of Oslerus osleri (Nematoda: Filaroididae) in the Andean fox (Lycalopex culpaeus)

Oslerus osleri is a cosmopolitan filaroid nematode that parasitizes the respiratory system of domestic and wild canids. Natural infection by O. osleri is reported in the Andean fox (Lycalopex culpaeus) in this study. Nematodes, enclosed in small and compact fibrous nodules of 1 to 5 mm in diameter, were found on the surface of the trachea near the bronchial bifurcation on four Andean foxes during necropsy (one from Cuzco, Peru and three from Northwestern Patagonia in Argentina). The nematodes were identified as O. osleri by morphological and molecular methods. Ribosomal and mitochondrial DNA analyses were performed amplifying the second internal transcribed spacer region (ITS-2), the partial cytochrome c oxidase 1 (cox1), and the large subunit of nuclear ribosomal RNA (LSU rRNA) genes. Sequences of the ITS-2 and LSU rRNA had a genetic variation of 1.5% and 1.0%, respectively, with previous sequences of O. osleri registered in Genbank. This is the first amplification of the cox1 gene of O. osleri and demonstrated an identity of 92% to Perostrongylus falciformis (KY365437), and 90% to Angiostrongylus cantonensis (KY779735) and Angiostrongylus costaricensis (AP017675).Fil: Gomez Puerta, Luis A.. Universidad Nacional Mayor de San Marcos; PerúFil: Flores, Verónica Roxana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Departamento de Zoología. Laboratorio de Parasitología; ArgentinaFil: Vega, Rocío Marisol. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Departamento de Zoología. Laboratorio de Parasitología; ArgentinaFil: Brugni, Norma Leonor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Departamento de Zoología. Laboratorio de Parasitología; ArgentinaFil: Viozzi, Gustavo Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Departamento de Zoología. Laboratorio de Parasitología; ArgentinaFil: Lopez Urbina, Maria T.. Universidad Nacional Mayor de San Marcos; PerúFil: Gonzalez, Armando E.. Universidad Nacional Mayor de San Marcos; Per

Infección natural por Fasciola hepatica en cérvidos del Perú

Natural infection by Fasciola hepatica is recorded in a white-tailed deer (Odocoileus virginianus) and a taruca (Hippocamelus antisensis), both from the department of Cusco. Animals were remitted to the Veterinary Institute (IVITA-Maranganí, FMV, UNMSM) by the authorities of the National Service of Flora and Fauna (SERFOR, Cusco Headquarters). Six trematodes were collected from the bile ducts during the necropsy of the animals, and they were preserved in 70% ethanol. Morphological analysis indicated that they correspond to F. hepatica. This was confirmed by analyzing of the mitochondrial DNA of the parasites by partially amplifying the cytochrome c oxidase subunit 1 (cox1) and the NADH dehydrogenase subunit 1 (nad1) genes. Analysis of these genes had an identity greater than 99% compared to genes from GenBank. The present study demonstrates the occurrence of F. hepatica in these cervids, thus adding two new definitive hosts for the parasite.En el presente trabajo se registra la infección natural por Fasciola hepaticaen un venado de cola blanca (Odocoileus virginianus) y en una taruca (Hippocamelus antisensis), ambos procedentes del departamento de Cusco. Los animales fueron remitidos al Instituto Veterinario (IVITA-Maranganí, FMV, UNMSM) por las autoridades del Servicio Nacional de Flora y Fauna (SERFOR, Sede Cusco). Durante la necropsia de los animales se colectaron seis trematodos de los conductos biliares, los cuales fueron preservados en etanol al 70%. Las observaciones morfológicas indicaron que se trataban de F. hepatica. Esto fue confirmado analizando el ADN mitocondrial de los parásitos amplificando parcialmente los genes citocromo c oxidasa subunidad 1 (cox1) y el NADH deshidrogenasa subunidad 1 (nad1). El análisis de estos genes tuvo una identidad mayor al 99% comparado con registros del banco de genes (GenBank). El presente estudio demuestra la presencia de F. hepatica en estos cérvidos, agregando así dos nuevos hospederos definitivos para el parásito

Venezuela's humanitarian crisis, resurgence of vector-borne diseases, and implications for spillover in the region.

In the past 5-10 years, Venezuela has faced a severe economic crisis, precipitated by political instability and declining oil revenue. Public health provision has been affected particularly. In this Review, we assess the impact of Venezuela's health-care crisis on vector-borne diseases, and the spillover into neighbouring countries. Between 2000 and 2015, Venezuela witnessed a 359% increase in malaria cases, followed by a 71% increase in 2017 (411 586 cases) compared with 2016 (240 613). Neighbouring countries, such as Brazil, have reported an escalating trend of imported malaria cases from Venezuela, from 1538 in 2014 to 3129 in 2017. In Venezuela, active Chagas disease transmission has been reported, with seroprevalence in children (<10 years), estimated to be as high as 12·5% in one community tested (n=64). Dengue incidence increased by more than four times between 1990 and 2016. The estimated incidence of chikungunya during its epidemic peak is 6975 cases per 100 000 people and that of Zika virus is 2057 cases per 100 000 people. The re-emergence of many vector-borne diseases represents a public health crisis in Venezuela and has the possibility of severely undermining regional disease elimination efforts. National, regional, and global authorities must take action to address these worsening epidemics and prevent their expansion beyond Venezuelan borders

Laparoscopy in management of appendicitis in high-, middle-, and low-income countries: a multicenter, prospective, cohort study.

BACKGROUND: Appendicitis is the most common abdominal surgical emergency worldwide. Differences between high- and low-income settings in the availability of laparoscopic appendectomy, alternative management choices, and outcomes are poorly described. The aim was to identify variation in surgical management and outcomes of appendicitis within low-, middle-, and high-Human Development Index (HDI) countries worldwide. METHODS: This is a multicenter, international prospective cohort study. Consecutive sampling of patients undergoing emergency appendectomy over 6 months was conducted. Follow-up lasted 30 days. RESULTS: 4546 patients from 52 countries underwent appendectomy (2499 high-, 1540 middle-, and 507 low-HDI groups). Surgical site infection (SSI) rates were higher in low-HDI (OR 2.57, 95% CI 1.33-4.99, p = 0.005) but not middle-HDI countries (OR 1.38, 95% CI 0.76-2.52, p = 0.291), compared with high-HDI countries after adjustment. A laparoscopic approach was common in high-HDI countries (1693/2499, 67.7%), but infrequent in low-HDI (41/507, 8.1%) and middle-HDI (132/1540, 8.6%) groups. After accounting for case-mix, laparoscopy was still associated with fewer overall complications (OR 0.55, 95% CI 0.42-0.71, p < 0.001) and SSIs (OR 0.22, 95% CI 0.14-0.33, p < 0.001). In propensity-score matched groups within low-/middle-HDI countries, laparoscopy was still associated with fewer overall complications (OR 0.23 95% CI 0.11-0.44) and SSI (OR 0.21 95% CI 0.09-0.45). CONCLUSION: A laparoscopic approach is associated with better outcomes and availability appears to differ by country HDI. Despite the profound clinical, operational, and financial barriers to its widespread introduction, laparoscopy could significantly improve outcomes for patients in low-resource environments. TRIAL REGISTRATION: NCT02179112

Pooled analysis of WHO Surgical Safety Checklist use and mortality after emergency laparotomy

Background The World Health Organization (WHO) Surgical Safety Checklist has fostered safe practice for 10 years, yet its place in emergency surgery has not been assessed on a global scale. The aim of this study was to evaluate reported checklist use in emergency settings and examine the relationship with perioperative mortality in patients who had emergency laparotomy. Methods In two multinational cohort studies, adults undergoing emergency laparotomy were compared with those having elective gastrointestinal surgery. Relationships between reported checklist use and mortality were determined using multivariable logistic regression and bootstrapped simulation. Results Of 12 296 patients included from 76 countries, 4843 underwent emergency laparotomy. After adjusting for patient and disease factors, checklist use before emergency laparotomy was more common in countries with a high Human Development Index (HDI) (2455 of 2741, 89.6 per cent) compared with that in countries with a middle (753 of 1242, 60.6 per cent; odds ratio (OR) 0.17, 95 per cent c.i. 0.14 to 0.21, P <0001) or low (363 of 860, 422 per cent; OR 008, 007 to 010, P <0.001) HDI. Checklist use was less common in elective surgery than for emergency laparotomy in high-HDI countries (risk difference -94 (95 per cent c.i. -11.9 to -6.9) per cent; P <0001), but the relationship was reversed in low-HDI countries (+121 (+7.0 to +173) per cent; P <0001). In multivariable models, checklist use was associated with a lower 30-day perioperative mortality (OR 0.60, 0.50 to 073; P <0.001). The greatest absolute benefit was seen for emergency surgery in low- and middle-HDI countries. Conclusion Checklist use in emergency laparotomy was associated with a significantly lower perioperative mortality rate. Checklist use in low-HDI countries was half that in high-HDI countries.Peer reviewe

Energy Transfer in Colloidal Photonic Crystals

nrpages: 127status: publishe

International Supply Chain Management-AN85-201801

International Supply Chain Management es un curso de la línea técnica de la carrera de Administración yNegocios Internacionales diseñado para capacitar a los estudiantes en temas relacionados a las actividades de lagestión logística de una empresa y el estudio de la metodología para la elección de una cadena óptima dedistribución física internacional