474 research outputs found
Self-Selection Patterns among Return Migrants: Mexico 1990-2010
This paper analyzes the self-selection patterns among Mexican return migrants during the period from 1990 to 2010. Using census data, we can identify return migrants who have lived in the United States within the previous 5 years but who currently live in Mexico. To calculate the selection patterns, we non parametrically estimate the counterfactual wages that the return migrants would have experienced had they never migrated by using the wage structure of non migrants. We find evidence that the selection patterns change over time toward negative selection. For example, in 1990, the wages that the male return migrants would have experienced had they not migrated was 6 percent larger than the wages of male non migrants. However, by 2010, the difference had declined to -14 percent. The increasing negativity of the degree of selection is robust to the analysis of specific subgroups: rural and urban, men and women, and states with high migration rates and low migration rates. Moreover, the negative selection results for the period from 2000 to 2010 are robust to the use of different surveys that define a return migrant by using distinct characteristics. Additionally, we observe that the wages of return migrants are larger than those that the migrants would have obtained had they not migrated. This finding shows that migration has a positive effect on the Mexican economy.Mexican migration, self-selection, return migration, wages
Provenance does matter: links between winter trophic segregation and the migratory origins of European robins
Amongst migratory species, it is common to find individuals from different populations or geographical origins sharing staging or wintering areas. Given their differing life histories, ecological theory would predict that the different groups of individuals should exhibit some level of niche segregation. This has rarely been investigated because of the difficulty in assigning migrating individuals to breeding areas. Here, we start by documenting a broad geographical gradient of hydrogen isotopes (δ2H) in robin Erithacus rubecula feathers across Europe. We then use δ2H, as well as wing-tip shape, as surrogates for broad migratory origin of birds wintering in Iberia, to investigate the ecological segregation of populations. Wintering robins of different sexes, ages and body sizes are known to segregate between habitats in Iberia. This has been attributed to the despotic exclusion of inferior competitors from the best patches by dominant individuals. We find no segregation between habitats in relation to δ2H in feathers, or to wing-tip shape, which suggests that no major asymmetries in competitive ability exist between migrant robins of different origins. Trophic level (inferred from nitrogen isotopes in blood) correlated both with δ2H in feathers and with wing-tip shape, showing that individuals from different geographic origins display a degree of ecological segregation in shared winter quarters. Isotopic mixing models indicate that wintering birds originating from more northerly populations consume more invertebrates. Our multi-scale study suggests that trophic-niche segregation may result from specializations (arising in the population-specific breeding areas) that are transported by the migrants into the shared wintering grounds
Near-Ground Wireless Coverage Design in Rural Environments
[EN] Due to the broad range of options that wireless systems offer, Wi-Fi products are increasingly being used in agriculture environments to improve farming practices and better control the output of the production. However, the foliage has proven to harm radio-frequency propagation as well as decreasing the coverage area of Wireless Sensor Networks (WSNs). Therefore, near-ground channel characterization can help in avoiding high antennas and vegetation. Nevertheless, theoretical models tend to fail when forecasting near-ground path losses. This paper aims at determining how the field components such as soil, grass and, trunks affect radio-links in near-ground scenarios. To do this, we measure the Received Signal Strength (RSSI), the Signal to Interference Ratio (SIR) and the Round-Trip Time (RTT) of a Wireless Local Area Network (WLAN), at different distances, and the results are compared with 3 prediction models: the Free-Space Propagation Model, Two-Ray Ground Reflection Model and, One-Slope Log-Normal Model. The experiment was carried out by collecting experimental data at two different locations, i.e., an orange tree plantation and a field without vegetation, taking measurements every meter. A comprehensive analysis of the influence of rural environments can help to obtain better near-ground WSN performance and coverage in precision agriculture.This work has been partially supported by European
Union through the ERANETMED project ERANETMED3-
227 SMARTWATIR, by the Ministerio de Ciencia,
Innovación y Universidades through the Ayudas para la
adquisición de equipamiento científico-técnico,
Subprograma estatal de infraestructuras de investigación y
equipamiento científico-técnico (plan Estatal I+D+i 2017-
2020) (project EQC2018-004988-P), by the Universidad de
Granada through the "Programa de Proyectos de
Investigación Precompetitivos para Jóvenes Investigadores.
Modalidad A jóvenes Doctores of "Plan Propio de
Investigación y Transferencia 2019" (PPJIA2019.10) and by
the Campus de Excelencia Internacional Global del Mar
(CEI·Mar) through the "Ayudas Proyectos Jóvenes
Investigadores CEI·Mar 2019" (Project CEIJ-020).Botella-Campos, M.; Jimenez, JM.; Sendra, S.; Lloret, J. (2020). Near-Ground Wireless Coverage Design in Rural Environments. IARIA XPS Press. 14-19. http://hdl.handle.net/10251/178039S141
Perioperative Complications in Plastic Surgery
Anesthetic complications in the perioperative period in plastic surgery are extremely rare, although they can be catastrophic and sometimes fatal. The proper selection and correct preoperative assessment of patients are the key to stay away from unwanted events. Preanesthesia evaluation is mandatory in each patient and must include clinical history, complete physical examination, and routine and special laboratory tests in patients with associated pathologies. Anesthetic management is based on these results, type of surgery, experience of the anesthesiologist, and the operating environment. The anesthetic technique can be local, regional, or general with standard noninvasive monitoring. It is recommended that an anesthesiologist be present in all plastic surgery procedures. Complications are usually the result of moving away from the guidelines already established for an excellent practice or the result of sentinel events rather than human errors. Pulmonary embolism is probably the most feared complication, with soft tissue infections being the most frequent complication in plastic surgery. Less common complications include arrhythmias, overhydration, allergies, bleeding, skin necrosis, dehiscence of wounds, brain damage, and dead. Anesthesiologists, surgeons, nurses, and all personnel involved in the care of these patients must work as a team of highly qualified and updated professionals
Parasitic wasp responses to symbiont-based defense in aphids
BACKGROUND: Recent findings indicate that several insect lineages receive protection against particular natural enemies through infection with heritable symbionts, but little is yet known about whether enemies are able to discriminate and respond to symbiont-based defense. The pea aphid, Acyrthosiphon pisum, receives protection against the parasitic wasp, Aphidius ervi, when infected with the bacterial symbiont Hamiltonella defensa and its associated bacteriophage APSE (Acyrthosiphon pisum secondary endosymbiont). Internally developing parasitoid wasps, such as A. ervi, use maternal and embryonic factors to create an environment suitable for developing wasps. If more than one parasitoid egg is deposited into a single aphid host (superparasitism), then additional complements of these factors may contribute to the successful development of the single parasitoid that emerges. RESULTS: We performed experiments to determine if superparasitism is a tactic allowing wasps to overcome symbiont-mediated defense. We found that the deposition of two eggs into symbiont-protected aphids significantly increased rates of successful parasitism relative to singly parasitized aphids. We then conducted behavioral assays to determine whether A. ervi selectively superparasitizes H. defensa-infected aphids. In choice tests, we found that A. ervi tends to deposit a single egg in uninfected aphids, but two or more eggs in H. defensa-infected aphids, indicating that oviposition choices may be largely determined by infection status. Finally, we identified differences in the quantity of the trans-β-farnesene, the major component of aphid alarm pheromone, between H. defensa-infected and uninfected aphids, which may form the basis for discrimination. CONCLUSIONS: Here we show that the parasitic wasp A. ervi discriminates among symbiont-infected and uninfected aphids, and changes its oviposition behavior in a way that increases the likelihood of overcoming symbiont-based defense. More generally, our results indicate that natural enemies are not passive victims of defensive symbionts, and that an evolutionary arms race between A. pisum and the parasitoid A. ervi may be mediated by a bacterial symbiosis
Development of a Roadmap for the Implementation of a Sustainable Mobility Action Plan in University Campuses of Emerging Countries
Universities are centers of knowledge and their Campuses are like small cities, thus making them the ideal place to develop, apply and evaluate policies and tools for innovative mobility solutions that can subsequently be extended to other contexts. A review of mobility measures in different European Universities has revealed that many of them apply policies to promote sustainable mobility, but there is a significant lack of standardized mobility plans and roadmaps for their successful implementation. The objective of the present work is to develop a successful roadmap, which is necessary for the smooth implementation of a mobility plan, as it has been found through a thorough review of good practices in Universities. Within this framework, a customizable standardized Roadmap design is proposed, which consists of two documents: a tactical document that provides a global and sequential vision of the entire plan, and an operational document that details the actions for each strategic line. This roadmap is accompanied by a catalog of objectives, measures, and cost and impact indicators. We consider this design instructive for universities because of its universal characteristics in Emerging Countries. To ensure this, it is necessary to apply this roadmap and carry out the corresponding evaluation
Prevalencia de secuelas en pacientes con diabetes mellitus tipo 2 sobrevivientes al COVID-19
Objective: To assess whether there is an association between the prevalence of sequelae due to COVID-19 and type 2 diabetes mellitus. Material and methods: Cross-sectional analytical design. A structured questionnaire, validated by experts, was applied by telephone to patients who had been discharged for at least three months, and clinical data was obtained from their medical records. An informed consent was applied. Results: 52% were male (p=0,5); the median age was 57 years (IQR: 21), and the time between discharge and interview was 9 months. The severity of COVID-19 was: moderate 51%, severe 38%, critical 9%; diabetics 23,75% (p<0,05). An association was found between general sequelae and diabetes (OR=3,04, CI95%: 1,51-6,13, p: 0,001, RPa: 2,4), followed by cardiovascular sequelae (OR=2,91, CI95%: 1,57-5,38, p: 0,000, RPa: 2,1). Of the 57 diabetics, 85,9% had sequelae due to COVID-19; and of the 183 non-diabetics, 68,3% (p: 0,009, OR: 2,84, 95% CI: 1,26-6,38, PRc: 2,32). Conclusions: The prevalence of sequelae due to COVID-19 was higher in diabetic patients than in non-diabetic patients; the most frequent type of sequelae was fatigue.Objetivo: Evaluar si existe asociación entre la prevalencia de secuelas por COVID-19 y diabetes mellitus tipo 2. Material y métodos: Diseño analítico trasversal. Se aplicó por teléfono un cuestionario estructurado, validado por expertos, a pacientes con al menos tres meses de alta y se obtuvieron datos clínicos de sus historias clínicas. Se aplicó un consentimiento informado. Resultados: El 52% fueron varones (p=0,5); la mediana de edad 57 años(RIC:21), y el tiempo entre alta y entrevista fue 9 meses. La severidad de COVID-19 fue: moderado 51%, grave 38%, critico 9%; diabéticos 23,75% (p<0,05). Se halló asociación entre secuelas generales y diabetes (OR=3,04, IC95%: 1,51-6,13, p:0,001, RPa:2,4), seguida por secuelas cardiovasculares (OR=2,91, IC95%: 1,57-5,38, p:0,000, RPa:2,1). De los 57 diabéticos, 85,9% hicieron secuelas por COVID-19; y de los 183 no diabéticos, el 68,3% (p: 0,009, OR:2,84, IC95%:1,26-6,38, RPc:2,32). Conclusiones: La prevalencia de secuelas por COVID-19 fue mayor en pacientes diabéticos que en los no diabéticos; el tipo de secuelas más frecuente fue fatiga
- …