Abstract: The cerambycid insect Xylotrechus arvicola is considered a pest that affects the wood of the grapevine (Vitis vinifera) in the major wine areas of the Iberian Peninsula. The larva of this insect perforates the grapevine wood, resulting in structural and biomechanical failure of the vine plants. Vine samples from wood damaged by X. arvicola larvae were picked up from different vineyards and grape varieties. Compressive and flexural tests were performed in order to assess the mechanical behaviour of the wood samples. Total length of the cracks in wood samples (TLCWS) that appeared on the surface of the grapevine wood samples after the mechanical tests was measured. Compressive strength (CS) and flexural strength (FS) decreased with the increase of the cross-sectional area (CSA) of both branches and trunks, regardless of damage condition or water content. Moreover, the resistance was lower in damaged wood. In addition, this was verified through the linear regression coefficients of the interaction CS x CSA and FS x CSA. TLCWS in branches and trunks of damaged samples was greater that in undamaged samples. Also, TLCWS within the same damage condition and part of the plant was higher in dry samples than in fresh samples. The damaged wood would show a higher vulnerability to common mechanical stress suffered by the grapevines in the field including heavy winds, fruit overweight or harvesting machines shaking (when mechanically collected). Larvae of this insect altered the mechanical behaviour of the trunk and branches of grapevine wood. The mechanical strength of wood was more negatively affected when the CSA of the branches and trunks increased. Longer TLCWS was found in affected wood.

Abstract Objective: To identify preoperative risk factors associated with major complications in patients with xanthogranulomatous pyelonephritis undergoing total nephrectomy. Method: Retrospective analysis of patient's charts with xanthogranulomatous pyelonephritis who underwent nephrectomy. Risk factors included for analysis were gender, body mass index, Charlson comorbidity index, American Society of Anesthesiologists physical status classification, Malek's stage, leukocyte count and creatinine levels. Postoperative complications were stratified in minor and major according to Clavien-Dindo's classification. Univariate and bivariate analysis using Fisher's exact test, Pearson's chi-squared and odds ratio (OR) was performed. Results: 72 patients were analyzed, 83% women, mean age of 50 years, 58.3% positive urine cultures and 66% kidney stones. Major complications were present in 32% of cases, and 15% were admitted to the intensive care unit. Elevated creatinine (OR: 3.8; 95% confidence interval [95%CI]: 1.1-13; p = 0.02) and Malek's stage II to III (OR: 4.5; 95%CI: 1.2-17.5; p = 0.02) were associated with major complications. Conclusion: The Malek Stage and elevated creatinine increases the risk of major complications in patients undergoing nephrectomy due to xanthogranulomatous pyelonephritis.

Resumen Objetivo: Identificar factores de riesgo asociados a complicaciones mayores en pacientes con pielonefritis xantogranulomatosa sometidos a nefrectomía. Método: Análisis retrospectivo de expedientes clínicos de pacientes con pielonefritis xantogranulomatosa sometidos a nefrectomía. Se analizaron el sexo, el índice de masa corporal, el índice de comorbilidad de Charlson, la clasificación del estado físico de la American Society of Anesthesiologists, la etapa de Malek, el conteo leucocitario y los valores de creatinina. Las complicaciones se estratificaron en menores y mayores según la clasificación de Clavien-Dindo. Se realizó análisis univariado y bivariado usando las pruebas exacta de Fisher y ji al cuadrado de Pearson, y se establecieron medidas de riesgo utilizando la odds ratio (OR). Resultados: Se analizaron 72 pacientes con una edad media de 50 años, el 83% mujeres, el 58.3% con urocultivo positivo y el 66% con litiasis renal. El 32% tuvieron alguna complicación mayor y el 15% requirieron admisión a la unidad de cuidados intensivos. Los valores elevados de creatinina (OR: 3.8; intervalo de confianza del 95% [IC95%]: 1.1-13; p = 0.02) y la etapa Malek II-III (OR: 4.5; IC95%: 1.2-17.5; p = 0.02) se asociaron con complicaciones mayores. Conclusión: El estadio de Malek y los valores elevados de creatinina incrementan el riesgo de desarrollar complicaciones mayores en los pacientes con pielonefritis xantogranulomatosa sometidos a nefrectomía.

RESUMEN En el presente artículo nos proponemos analizar la filosofía de la religión y la crítica que se hace a esta, tomando como anclaje los planteamientos de Ludwig Feuerbach, como primer gran exponente del ateísmo moderno. Para ello, partiremos de una serie de pensadores que se pueden considerar como precedentes de las ideas del autor alemán, llegando después a los planteamientos feuerbachianos y acabando en una valoración de los filósofos que, tras él, han construido una filosofía crítica de la religión y la teología, poniendo en conexión las innovaciones que Feuerbach llevó a cabo en disciplinas como la filosofía, la teología o la antropología, con cuestiones de candente actualidad, defendiendo lo pertinente de este pensamiento, aun encontrándonos a un siglo y medio de distancia de la muerte de su autor.

ABSTRACT The aim of this article is to analyze the religion philosophy and its critic, based on Ludwig Feuerbach principles as one of the greatest exponents of modern atheism. It will start from some thinkers that could be considered as Ludwig predecessors, going through Feuerbachian considerations to finish with a valuation of those philosophers who have built a new critic philosophy of the religion and theology, relating some Feuerbach innovations in this fields with highly topical matters, proving the actual relevance of his thinking despite the fact that it has been a century and a half since his death.

Abstract: Xylotrechus arvicola is an insect pest on Vitis vinifera in the main wine-producing regions of Spain. X. arvicola larvae bore inside grapevine wood, which cause structural damages in the plants´ biomechanical properties. Grapevine wood affected and unaffected by larvae, were collected from vineyards. Compression and flexural tests were used to quantify biomechanical wood properties. Affected wood broke more quickly and endured a lower supported force than unaffected wood in both varieties and moisture states. Tempranillo was the most resistant variety on trunks, while Cabernet-Sauvignon was the most resistant variety on branches, where all infested varieties showed a lower rate of bending. Grapevine wood affected by X. arvicola larvae shows an important decrease in its resistance in both moisture states - dry and wet wood - and it is observed due to the faster break in time and a lower supported force. These damages give the affected wood greater sensitivity to external mechanical factors in the vineyards, such as strong winds, harvest weight and the vibration exerted by harvesting machines. The aspect of stress-time curves in all cases follow similar patterns, so in future studies might be possible to stablish relationships between both wet and dry samples and different infestation levels.

Abstract The importance of leadership for student learning is undeniable, but studies warn of a global crisis in the recruitment and retention of principals due to the complexities associated with this position. In Chile, principal selection favors the recruitment of external candidates over internal promotion, which entails difficulties derived from the insertion into a new school culture. This article introduces an alternative perspective and, through a qualitative case study, analyzes the trajectory of 10 municipal school principals selected through Senior Public Management (ADP) after a process of internal promotion. Findings are organized using the framework proposed by Moorosi (2010): Anticipation, future principals are identified early, exercise leadership informally and access professional learning opportunities; Acquisition, future principals access formal leadership positions, developing professional knowledge and increasing their visibility with the school community; and Performance, principals face the transition to office and must manage relationships with other relevant actors. Based on these findings, five lessons are discussed for a strategy of internal promotion of future school leaders that can complement external recruitment for a future principal career in Chile.

Resumen La relevancia del liderazgo para el mejoramiento del aprendizaje de los estudiantes es innegable, pero los estudios advierten de una crisis global en el reclutamiento y retención de directores debido a las complejidades asociadas al cargo. En Chile, la selección directiva favorece el reclutamiento de candidatos externos por sobre la promoción interna, lo que conlleva dificultades derivadas de la inserción en una cultura escolar nueva, en un contexto de alta rotación directiva. Este artículo presenta una mirada alternativa y, a través de un estudio de casos cualitativo, analiza la trayectoria de 10 directores de establecimientos municipales elegidos por Alta Dirección Pública (ADP), luego de un proceso de promoción interna. Los resultados se organizan utilizando el marco propuesto por Moorosi (2010): Anticipación, los futuros directores son identificados tempranamente, ejercen liderazgo de manera informal y acceden a oportunidades de aprendizaje profesional; Adquisición, los futuros directores acceden a puestos de liderazgo formal, desarrollando conocimientos profesionales y aumentando su visibilidad frente a la comunidad escolar; y Desempeño, los directores enfrentan la transición al cargo y deben manejar las relaciones con otros actores relevantes. A partir de estos hallazgos, se discuten cinco lecciones acerca de la promoción interna de líderes escolares de modo que complemente el reclutamiento externo en una futura carrera directiva en Chile.

Abstract It is often unclear to the clinical investigator whether observational studies should be submitted to a research ethics committee (REC), mostly because, in general, no active or additional interventions are performed. Moreover, obtaining an informed consent under these circumstances may be challenging, either because these are very large epidemiological registries, or the subject may no longer be alive, is too ill to consent, or is impossible to contact after being discharged. Although observational studies do not involve interventions, they entail ethical concerns, including threats such as breaches in confidentiality and autonomy, and respect for basic rights of the research subjects according to the good clinical practices. In this context, in addition to their main function as evaluators from an ethical, methodological, and regulatory point of view, the RECs serve as mediators between the research subjects, looking after their basic rights, and the investigator or institution, safeguarding them from both legal and unethical perils that the investigation could engage, by ensuring that all procedures are performed following the international standards of care for research. The aim of this manuscript is to provide information on each type of study and its risks, along with actions to prevent such risks, and the function of RECs in each type of study.

Resumo Objetivo: Analisar os fundamentos, o prognóstico e o estabelecimento da terapia de oxigenação por membrana extracorpórea ECMO neonatal-pediátrica em países da América Latina com recursos limitados. Fontes: A base de dados PubMed foi explorada de 1985 até hoje, selecionamos os principais periódicos da América Latina e relatos da Organização de Suporte de Vida Extracorpóreo. Resumo dos achados: A oxigenação por membrana extracorpórea proporciona “tempo” para descanso pulmonar e cardíaco e para recuperação. Ela é usada no campo neonatal-pediátrico como terapia de resgate, com mais de 1.300 pacientes com insuficiência respiratória e cerca de 1.000 pacientes com cardiopatias por ano. Os melhores resultados de sobrevida de curto e longo prazo são de pacientes com doenças respiratórias isoladas, o que estabelece uma terapia padrão em centros de encaminhamento para pacientes de alto risco. O primeiro programa de oxigenação por membrana extracorpórea neonatal/pediátrico na América Latina foi estabelecido no Chile em 2003, que também foi o primeiro programa na América Latina a se afiliar à Organização de Suporte de Vida Extracorpóreo. Novos programas de oxigenação por membrana extracorpórea foram desenvolvidos nos últimos anos em centros de encaminhamento em Argentina, Colômbia, Brasil, México, Peru, Costa Rica e Chile, que atualmente fundam a seção da América Latina da Organização de Suporte de Vida Extracorpóreo. Conclusões: Os melhores resultados de sobrevida de curto e longo prazo são de pacientes com doenças respiratórias isoladas. Atualmente, a terapia de oxigenação por membrana extracorpórea é uma terapia padrão em alguns centros de encaminhamento da América Latina. Esperamos que esses novos centros de oxigenação por membrana extracorpórea tenham um impacto positivo sobre a sobrevida de neonatos e crianças com insuficiência respiratória ou cardíaca e que estejam disponíveis para um número cada vez maior de pacientes de nossa região no futuro próximo.

Abstract Objective: To review the principles of neonatal-pediatric extracorporeal membrane oxygenation therapy, prognosis, and its establishment in limited resource-limited countries in Latino America. Sources: The PubMed database was explored from 1985 up to the present, selecting from highly-indexed and leading Latin American journals, and Extracorporeal Life Support Organization reports. Summary of the findings: Extracorporeal membrane oxygenation provides “time” for pulmonary and cardiac rest and for recovery. It is used in the neonatal-pediatric field as a rescue therapy for more than 1300 patients with respiratory failure and around 1000 patients with cardiac diseases per year. The best results in short- and long-term survival are among patients with isolated respiratory diseases, currently established as a standard therapy in referral centers for high-risk patients. The first neonatal/pediatric extracorporeal membrane oxygenation Program in Latin America was established in Chile in 2003, which was also the first program in Latin America to affiliate with the Extracorporeal Life Support Organization. New extracorporeal membrane oxygenation programs have been developed in recent years in referral centers in Argentina, Colombia, Brazil, Mexico, Perú, Costa Rica, and Chile, which are currently funding the Latin American Extracorporeal Life Support Organization chapter. Conclusions: The best results in short- and long-term survival are in patients with isolated respiratory diseases. Today extracorporeal membrane oxygenation therapy is a standard therapy in some Latin American referral centers. It is hoped that these new extracorporeal membrane oxygenation centers will have a positive impact on the survival of newborns and children with respiratory or cardiac failure, and that they will be available for an increasing number of patients from this region in the near future.

This is an updated review of screening, early diagnosis and treatment of hepatocellular carcinoma, focusing on the advancements occurred in the last years and highlighting the challenges in clinical research. Hepatocellular carcinoma (HCC) is nowadays the sixth most frequent cancer worldwide with up to 740,000 new cases diagnosed each year, and it is the third most prevalent cause of cancer-related-death worldwide (1). This neoplasm usually appears linked to an underlying liver disease, being one of the most relevant causes of death in patients diagnosed of liver cirrhosis (2,3). In the last years, important advancements in terms of diagnosis, staging and treatment of HCC, improving the management and outcome of the disease, have been made (4-7). Despite the fact that these improvements have absolutely changed natural history of HCC, there are several areas that still need further advancements. The aim of this document is to discuss some controversial aspects, which in our opinion constitute real challenges in clinical research of HCC.

Esta es una revisión actualizada de los distintos aspectos de cribado, diagnóstico precoz y tratamiento del carcinoma hepatocelular destacando especialmente los cambios sucedidos en los últimos dos años y las áreas de mejora que requieren trabajos de investigación clínica. El carcinoma hepatocelular (CHC) constituye actualmente el sexto cáncer más frecuente, con más de 740.000 casos diagnosticados anualmente, y la tercera causa de muerte por neoplasia a nivel mundial (1). Esta neoplasia aparece frecuentemente asociada a la presencia de una enfermedad hepática, siendo una de las principales causas de muerte en los pacientes afectos de cirrosis hepática (2,3). En los últimos años han aparecido novedades importantes en el diagnóstico, estadiaje y tratamiento del CHC que han permitido una mejora en el manejo de esta enfermedad (4-7). A pesar de que estos avances han cambiado completamente la historia natural del CHC, existen aún muchas áreas en las que se precisan avances para poder mejorar. El objetivo de este documento es discutir algunos aspectos controvertidos que a nuestro juicio constituyen retos en la investigación clínica del CHC.

In Chile, as in many South American countries, AASHTO-93 is the current official method for the design of asphalt pavements. The method gives an estimated number of 80 kN standard axle loads (W18) that the pavement can withstand for a certain serviceability. A safety factor is then applied to W18 to take into account the confidence level and the estimated variance of the inputs used in the method, whereby the magnitude of the structure’s life cycle is estimated. Normally, data used in the AASHTO-93 method are assumed to be deterministic, disregarding their random nature. This paper presents a probabilistic assessment of the AASHTO-93 pavement design method under Chilean conditions, which provides a set of probability density functions (PDFs) that allow a probabilistic estimation of the pavement life cycle in terms of the value W18. To achieve the goal, we developed a simulation model based on a sample of 13 groups of roads located throughout Chile.

En Chile, como en muchos países de Suramérica, AASHTO 93 es el método oficial para el diseño de pavimentos asfálticos. El método entrega un número estimado de ejes equivalentes estándar de 80 kN que el pavimento puede soportar hasta alcanzar un cierto valor de serviciabilidad. Un factor de seguridad es luego aplicado al número estimado de ejes equivalente tomando en cuenta el nivel de confianza y la varianza estimada de los datos de entrada utilizados en el método, con lo cuál se estima la magnitud del ciclo de vida de la estructura. Normalmente, los datos utilizados en el método AASHTO 93 son asumidos como valores deterministas, sin tomar en cuenta su naturaleza aleatoria. Este trabajo presenta una evaluación probabilística del método de diseño AASHTO 93 de pavimentos bajo condiciones chilenas, el cuáll proporciona un conjunto de funciones de densidad de probabilidad, que permiten realizar la estimación probabilística del ciclo de vida del pavimento en términos del valor del número de ejes equivalente. Para alcanzar el objetivo se desarrollo un modelo de simulación a partir de una muestra de 13 grupos de carreteras ubicados a largo de Chile.

El síndrome de Burnout (SB) constituye un tipo de estrés laboral que se observa en profesionales de la salud que mantienen contacto directo y constante con otras personas. El objetivo del estudio fue determinarla prevalencia del síndrome de Burnout en residentes y médicos especialistas del servicio de anestesiología de la Ciudad Hospitalaria “Dr. Enrique Tejera”, periodo enero-julio 2015; distribuirlos según edad, cargo, centro de trabajo, años laborales; determinar su situación emocional según el agotamiento emocional, despersonalización y realización personal; además, diagnosticar el nivel de estrés laboral de los mismos. Se realizó una investigación de tipo descriptivo, con diseño de campo y transversal, cuya muestra estuvo constituida por la totalidad de la población, 64 médicos entre especialistas y residentes, previa firma de un consentimiento informado. Se utilizó el cuestionario de Maslach Burnout Inventory, para indagar la presencia del SB. Los resultados arrojaron la presencia de SB en un 64,1% de los médicos encuestados, siendo mayor en los residentes 73,3%, hubo predominio del género femenino 62,5%; en lo referente a cansancio emocional 34,4%, despersonalización 39,1% y falta de realización personal 81,2%. Se concluyó que el SB es prevalente en las tres cuartas partes de los médicos, que además tenían 32 años o menos, seis de cada diez eran mujeres y poco más de la mitad eran médicos residentes, demostrándose la necesidad de mejorar las condiciones de trabajo del servicio de anestesiología.

Burnout syndrome (BS) is a kind of occupational stress that is observed in health professionals who maintain direct and constant contact with others. The aim of the study wasdetermine the prevalence of Burnout syndrome in residents and medical service specialists of anesthesiology at the City Hospital “Dr. Enrique Tejera”, period January-July 2015; distribuit them according to age, office, workplace, working years; also the emotional situation as emotional exhaustion, depersonalization and personal accomplishment was determined, besides the level of work stress of them was diagnosed. It was made a descriptive, with field design and transversal research, whose sample consisted of the entire population, 64 medical specialists and residents, after signing an informed consent. The Maslach Burnout Inventory questionnaire was used to investigate the presence of BS. The results showed the presence of BS in 64.1% of the surveyed physicians, being higher in residents with 73.3%, there was predominance of female 62.5%; in terms of emotional exhaustion 34.4 %, depersonalization 39.1% and lack of personal fulfillment 81.2%. It was concluded that BS is prevalent in the three quarters of doctors, who also had 32 years or less, six out of ten were women and just over half were resident physicians, demonstrating the need for better working conditions of anesthesiology service.

The following paper presents the results of a research aimed to firstly assess how the cultural capital of students obtained in their last year of high school influences their aspirations to attend a selective university and their degree of achievement. An original questionnaire was applied to 1054 students in 23 different educational establishments of Concepcion Metropolitan Area. The analysis shows a persistent influence of cultural capital on aspirations and their subsequent realization even after incorporating variables related to the student academic achievement. Furthermore, this study confirms a strong influence of the school socioeconomic composition even after taking into account the student academic level and their family cultural capital. Finally, it shows that strategies adopted by students to facilitate their entering into university, as attending courses to prepare entrance exams, strongly affect aspirations and completion of university studies. Inequality in access is considerably influenced by objective structural factors but also by the rational choice strategies undertaken by students.

Este artículo investiga, en primer lugar, la influencia del capital cultural sobre las aspiraciones a estudiar en una universidad selectiva y la concreción de estas por parte de los alumnos, a partir del análisis de un cuestionario original aplicado a 1.054 alumnos de cuarto año de enseñanza media en 23 colegios científico-humanistas del Gran Concepción. Se comprueba que existe, aun después de incorporar variables relativas al rendimiento académico del alumno, una persistencia de la influencia del capital cultural sobre las aspiraciones y su concreción. Por otro lado, el estudio confirma la gran influencia de la composición socioeconómica del colegio, incluso después de haber tomado en consideración el nivel académico de los alumnos y el capital cultural familiar. Finalmente, se demuestra que la adopción por parte de los alumnos de estrategias racionales que favorezcan la transición hacia la universidad, como la asistencia a un preuniversitario, incide notablemente en las aspiraciones y concreción de estudios universitarios. La marcada desigualdad en el acceso a la universidad se ve influenciada por factores estructurales objetivos, pero también por estrategias de elección racional asumidas por los actores involucrados.

P.M. Cañon, A.S. González, J.A. Alcalde, and E. Bordeu. 2014. Red wine phenolic composition: the effects of summer pruning and cluster thinning. Cien. Inv. Agr. 41(2): 235-248. The quality of red wine is directly associated with its phenolic composition, which can be controlled using several viticultural techniques that affect the vegetative/productive balance of the plants, such as summer pruning and cluster thinning. However, these techniques may also involve high costs and production losses. This study aimed to evaluate the effects of summer pruning and cluster thinning on the phenolic compositions of grapes and wine over three consecutive seasons. The treatments included long (120 cm shoot length) and short (60 cm shoot length) summer pruning and 50% cluster thinning with control treatments conducted in vineyards with cvs. Cabernet-Sauvignon and Carmenere and located in a warm area (Cachapoal, Chile) and cvs. Cabernet-Sauvignon and Pinot Noir located in a cold area (Casablanca, Chile). These treatments generated differences in the microclimatic conditions (radiation and temperature) and the vegetative/productive balance of the plants. Depending on whether the grapevine vigor was high or low, short summer pruning increased or decreased the phenolic composition. The effects of cluster thinning varied according to the natural productivity of each season, increasing the phenolic composition when the natural yields were high and producing no significant effects when they were low. The decision to make these viticultural practices to improve the phenolic composition of the wine depends on the seasonal vineyard vigor and potential productivity. Thus, measures are only applied when a severe imbalance in the vegetative/productive equilibrium occurs or when the microclimatic conditions of the vineyard must be improved.

P.M. Cañón, A.S. González, J.A. Alcalde y E. Bordeu. 2014. Composición fenólica del vino tinto: efecto de chapoda de brotes y raleo de racimos. Cien. Inv. Agr. 41(2): 235-248. La calidad del vino tinto está directamente relacionada con su composición fenólica, la cual puede ser manejada en el viñedo mediante técnicas vitícolas que afectan el equilibrio vegetativo-productivo de las plantas, pero que a la vez pueden implicar elevados costos y pérdidas de producción. Este estudio tuvo como objetivo evaluar en tres temporadas consecutivas, el efecto de las técnicas vitícolas de chapoda de brotes y raleo de racimos, sobre la composición fenólica de las uvas y el vino, bajo las condiciones vitícolas de Chile. Se aplicaron tratamientos de chapodas cortas (brotes de 60 cm) y largas (brotes de 120 cm) y raleo del 50% de los racimos y sin raleo, en viñedos de las variedades Cabernet-Sauvignon y Carmenere ubicados en una localidad cálida (Cachapoal, Chile), así como Cabernet-Sauvignon y Pinot noir ubicados en una localidad fría (Casablanca, Chile). Estos tratamientos generaron diferencias en las condiciones microclimáticas (radiación y temperatura) y en el equilibrio vegetativo/productivo de las plantas. Dependiendo si el vigor del viñedo era alto o bajo, la chapoda corta generó incrementos o disminuciones en la composición fenólica. El efecto del raleo de racimos sobre la composición fenólica se mostró dependiente de la productividad natural de cada temporada, presentando incrementos cuando los rendimientos eran altos y ausencia de efectos significativos cuando estos eran bajos. La decisión vitícola de realizar estas prácticas vitícolas con el fin mejorar la composición fenólica del vino dependerá del vigor y la productividad potencial que presente el viñedo en cada temporada, justificándose su aplicación solo cuando existan fuertes desbalances en el equilibrio vegetativo-productivo, o cuando se requiera mejorar las condiciones microclimáticas de las vides.

The purpose of this research was to achieve an advanced rheoiogicai characterization and classification for a set of modified and non-modified asphaltic bitumens currently employed in Chile. Six asphaltic bitumens were employed, which are locally produced by three asphalt manufacturer companies. Each company provided a traditional bitumen and a modified bitumen. The three traditional bitumens were classified as CA 24 and, SBS-modified bitumens were classified as 60-80. Rheological characterization tests were carried out by employing a dynamic shear rheometer and a bending beam rheometer on bitumens under original condition; primary ageing (RTFOT) and secondary ageing (PAV). Consequently, performance level, creep and recovery tests, master curves and Black's diagrams were determined for each bitumens. Besides, diverse and complete traditional tests were performed to the whole set of bitumens, in accordance to the aforementioned ageing levels. The rheological characterization enabled the determination of bitumen essential properties at high temperatures, intermediate temperatures and low temperatures. These properties together with an adequate cUmatologicaHy zoning of Chile could be employed to elaborate an updated specification for bitumens in our country. It was also demonstrated that traditional tests are only useful if they are carried out under the following conditions: high temperatures, intermediate temperatures, low temperatures, original binder, primary aged binder (RTFOT) and secondary aged binder (PAV). Only by executing tests under the aforementioned conditions, it is actually possible to achieve information and results comparable to the ones provided by Superpave.

El objetivo de esta investigación fue obtener una caracterización reológica y clasificación avanzada para un grupo de betunes asfálticos modificados y sin modificar utilizados actualmente en Chile. Estudiando seis betunes asfálticos, provenientes de tres empresas asfalteras del medio nacional. Cada empresa aportó con un betún tradicional y un betún modificado. Los tres betunes tradicionales clasificados como CA 24 y los tres modificados clasificados como 60-80 modificados con SBS. Se realizó la caracterización reológica utilizando un reómetro de corte dinámico y un reómetro de viga en flexión, para los betunes en estado original, envejecimiento primario (RTFOT) y envejecimiento secundario (PAV). Determinando para cada uno la clasificación por grado de desempeño, ensayo de fluencia y recuperación (creep and recovery), curvas maestras y diagramas de Black. Se realizó además una completa batería de ensayos tradicionales al total de los betunes asfálticos, para los tres niveles de envejecimiento mencionados. La caracterización reológica permitió determinar las propiedades fundamentales de los betunes a temperaturas altas, temperaturas intermedias y bajas temperaturas. Estas propiedades en conjunto con una adecuada zonificación climatológica de Chile, podrían ser utilizadas para confeccionar una especificación de betunes moderna para nuestro país.También se demostró que para que los ensayos tradicionales tengan alguna utilidad, deben ser realizados para las siguientes condiciones: altas temperaturas, temperaturas intermedias, bajas temperaturas, ligante original, ligante con envejecimiento primario (RTFOT) y ligante con envejecimiento secundario (PAV). Solamente cuando se realizan ensayos para todas las condiciones anteriores, es posible encontrar información y resultados que son comparables a los de Superpave.

Background: Treatment of children with Escherichia coli O157:H7 enterocolitis could be related with risk of Hemolytic-Uremic Syndrome (HUS). The proscription of antibiotics use until cultures ruled out this infection has been proposed (Wong et al.). This concept became generalized causing dilemma in clinical decisions and research. The objective of this study was to review the evidence related with this topic. Methods: A 1999-2011 literature review of studies related with E.coli O157:H7, antibiotics and HUS in children. Results: We found one randomized controlled trial, three cohort studies, one case-control and one meta-analysis with pediatric data on the topic. After methodological and metrical analysis, five studies showed opposite results as compared toWong et al. All had statistical power enough to detect Wong's association but did not happen. Wong's study had no statistical power to detect risk ratios ≤ 11. Conclusion: These results are neither reproducible nor generalizable, consequently clinical decisions should be solved following local epidemiology.

Antecedentes: El tratamiento de niños con enterocolitis por Escherichia coli O157:H7 estaría relacionado con alto riesgo de síndrome hemolítico-urémico (SHU). Se propuso la proscripción del uso de antimicrobianos hasta que los cultivos descartasen esta etiología (Wong y cols.). Este concepto se generalizó, causando dilemas para las decisiones clínicas y la investigación. El objetivo de este estudio fue revisar la evidencia relacionada con este tema. Métodos: Se realizó una búsqueda en la literatura 1999-2011de estudios relacionados con Escherichia coli 0157:H7, antimicrobianos, SHU y niños. Resultados: Encontramos un ensayo clínico controlado, tres estudios de cohortes, un caso-control con datos de niños y un meta-análisis. Al análisis metodológico y métrico, cinco estudios obtuvieron resultados opuestos al de Wong y cols. Todos tenían poder estadístico suficiente para detectar la medida de asociación de Wong y cols., pero ello no ocurrió. El estudio de Wong y cols. no tenía tal poder para detectar razones de riesgo ≤ 11. Conclusión: Los resultados de Wong y cols.no son reproducibles ni generalizables, por lo que las decisiones clínicas debieran resolverse según la epidemiología local, sin restricciones.