3,995 research outputs found

    Regional and international market integration of a small open economy

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    This paper studies the relationship between a set of commodity prices in a small open economy like Uruguay and the corresponding international and regional prices. The empirical methodology used is the multivariate cointegration procedure based on maximum likelihood methods introduced by Johansen (1988) as well as estimations of half-life persistence indicators. In the case of cereals, the evidence suggests strong market integration between domestic and regional markets and, to some extent, also to international markets. Therefore, directly or indirectly, domestic prices are connected with the efficient price signal. Results for beef indicate strong market integration between the domestic market and the regional market, which is not so well connected with international markets. Thus, domestic price appears to be linked to a regional price that is not linked to the efficient price signal.commodity prices, law of one price, market integration, cointegration

    Ressenyes

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    Obra ressenyada: Jeremy MUNDAY, Introducing Translation Studies. Londres y Nueva York: Routledge, 2000

    Analysis of the coating integrityduring a coronary stent deployment

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    Las afecciones cardiovasculares constituyen en la actualidad una causa frecuente de muerte. Una de estas afecciones es la ateroesclerosis, la cual provoca la reducción de la luz arterial. En aras de solucionar tal afección se han desarrollado varios tratamientos, ganando terreno la Angioplastia Coronaria Transluminar Percutánea (PTCA) con colocación de estent. En la actualidad muchos de estos dispositivos son recubiertos para aumentar la biocompatibilidad y disminuir los riesgos de reestenosis. Dado la posibilidad de fallas o roturas de los recubrimientos y los riesgos asociados a estas, es de gran importancia el estudio del comportamiento de la unión estentrecubrimiento durante la fase de expansión del estent. En esta investigación se estudia la posible ocurrencia de delaminación del recubrimiento durante la expansión de un estent y la influencia de parámetros como el espesor y el material del mismo. El estudio parte de la obtención de un modelo geométrico de una celda del estent Sirius Carbostent para su posterior procesamiento por el Método de Elementos Finitos. La simulación por tal método, se desarrolló, aplicando restricciones al movimiento de forma tal que la celda modelada simule su comportamiento durante la expansión de un estent. Considerando estos aspectos fue posible evaluar la integridad del recubrimiento. Con los modelos desarrollados se logró predecir la ocurrencia de delaminación durante la expansión del estent y se determinó que al aumentar el espesor del recubrimiento aumenta el riesgo de ocurrencia de la misma. Se obtuvo además una ecuación general que permite determinar el esfuerzo máximo de contacto para celdas en forma de U.The cardiovascular diseases constitute one of the main causes of death worldwide. One of the main diseases is atherosclerosis, which causes narrowing of the arterial lumen. In order to solve this condition, several treatments have been developed, and Percutaneous Transluminal Coronary Angioplasty (PTCA) with the placement of stent have gained relevancy. Many of these devices are currently coated to increase the biocompatibility and to decrease the restenosis risks. The biomechanical studies of the stent-coating interface behavior are necessary given the associated risks to possibility of failures or breakages of the coating during stent deployment. In this study the possible occurrence of coating delamination during stent deployment and the influence of parameters as the thickness and material were studied. The study starts by obtaining a geometric model of a stent unit of the Sirius Carbostent stent for the further processing by the Finite Element Method. The simulation was developed by applying restrictions so that the modeled stent hinge simulates his behavior during stent deployment. Considering these aspects it was possible to evaluation the coating integrity. With this model it was possible to predict the occurrence of delamination during stent deployment and to determine that the delamination risks increases with increasing the coating thickness. Finally, it was obtained a general function that allows to determine the maximal contact stress for a stent hinge with an U shape.Peer Reviewe

    Differences in kicking velocity and kicking deficit in young elite soccer players

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    El objetivo de este estudio fue examinar la evolución del rendimiento máximo de golpeo de balón a lo largo de la edad en futbolistas jóvenes de élite. Un total de 175 fueron divididos en 11 grupos edad (U-9 hasta U-19), además del equipo filial del club (U-23). Se registró la velocidad máxima de golpeo con la pierna dominante y no dominante mediante radar. El déficit de golpeo fue calculado para comparar el rendimiento entre ambas piernas. La velocidad máxima de golpeo aumenta progresivamente de forma significativa desde U-9 hasta U-16 con la pierna dominante y hasta U-18 con la no dominante, y sigue aumentando de forma no significativa hasta U-23. La etapa con mayor incremento de la velocidad de golpeo fue entre U-13 y U-16. Existe un déficit de golpeo con la pierna no dominante y sus valores permanecen estables (9.43%-18.18%) sin cambios significativos desde U-9 hasta U-23The purpose of this current study was to examine the age-related differences in kicking performance with both legs in 175 youth soccer players. Players from the development programme of a professional club were grouped according to their respective under-age team (U-9 to U-18), in addition to the club’s second team (U-23). Maximal kicking velocity with the preferred and non-preferred leg was recorded using a Doppler radar gun. Kicking deficit was calculated to compare side-to-side performance. Maximal kicking velocity improved progressively from the U-9 to U-16 age groups for the preferred leg and from U-16 to U-18 for the non-preferred leg, and continued to improve moderately but non-statistically significant until U-23. The stage of greatest kicking velocity development was between 13 and 16 years of age. There is a kicking deficit with the non-preferred leg and its values remain steady (9.43%-18.18%) without significant changes in players from U-9 to U-23 categorie

    Synthesis, characterization, bioactivity and biocompatibility of nanostructured materials based on the wollastonite-poly(ethylmethacrylate-co-vinylpyrrolidone) system

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    Composite materials are very promising biomaterials for hard tissue augmentation. The approach assayed in this work involves the manufacturing of a composite made of a bioactive ceramic, natural wollastonite (W) and a nanostructured copolymer of ethylmethacrylate (EMA) and vinylpyrrolidone (VP) to yield a bioresorbable and biocompatible VP–EMA copolymer. A bulk polymerization was induced thermally at 508C, using 1 wt % azobis(isobutyronitrile) (AIBN) as free-radical initiator. Structural characterization, compressive strength, flexural strength (FS), degradation, bioactivity, and biocompatibility were evaluated in specimens with a 60/40 VP/EMA ratio and ceramic content in the range 0–60%. A good integration between phases was achieved. Greater compression and FS, in comparison with the pure copolymer specimens was obtained only when the ceramic load got up to 60% of the total weight. The soaking in NaCl solution resulted in the initial swelling of the specimens tested. The maximum swelling was reached after 2–3 h of immersion and it was significantly greater for lower ceramic loads. This result makes the polymer component the main responsible for the interactions with the media. After soaking in SBF, microdomains segregation can be observed in the polymer component that can be related with a dramatic difference in the reactivity of both monomers in free radical polymerization, whereas the formation of an apatite-like layer on the W surfaces can be observed. Biocompatibility in vitro studies showed the absence of cytotoxicity of all formulations. The cells were able to adhere on the polystyrene negative control and on specimens containing 60 wt % wollastonite forming a monolayer and showing a normal morphology. However, a low cellular growth was observed. 2008 Wiley Periodicals, Inc. J Biomed Mater Res 88A: 53–64, 2009Peer reviewe

    On the bulk modulus and natural frequency of fullerene and nanotube carbon structures obtained with a beam based method

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    In this work, the natural frequency of vibration and Bulk modulus under hydrostatic pressure conditions of carbon nanotubes and fullerenes are investigated. For this purpose, three-dimensional finite element modelling is used in order to evaluate the vibration characteristics and radial stiffness for different nanotube and fullerene sizes. The atomistic method implemented in this work is based on the notion that nanotubes, or fullerenes, are geometrical frame-like structures where the primary bonds between two neighbouring atoms act like load-bearing beam members, whereas an individual atom acts as the joint of the related load-bearing system. The current numerical simulations results are compared with data reported by other authors, highlighting the greater simplicity and the lower computational cost of the model implemented in this work compared to other molecular dynamics models, maintaining accuracy in the results provided.The authors are indebted to the Ministerio de Economía y Competitividad de España (Projects DPI2011-24068 and DPI2011-23191) for the financial support.Publicad

    MetodologĂ­a de investigaciĂłn de los yacimientos de pizarras para cubiertas

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    [Resumen] Se exponen .las bases metodológicas autores aplican a la investigación y de yacimientos de pizarras para cubiertas, tanto de su propia experiencia como de bibliografía disponible sobre el tema. Los factores que controlan la calidad de los yacimientos de dicha materia prima son de tres tipos: Litoestratigráficos, estructurales y metamórficos. Ellos se reflejan en una serie de parámetros que son los que habitua1ment e s e evalúan en e1 campo. La investigación utiliza técnicas geológicas básicas, adaptadas a las peculiaridades de la pizarra. Aquélla se lleva a cabo en tres fases. De cada una de las fases se presentan ejemplos. Se apuntan también algunas nuevas técnicas de investigación tomadas de la bibliografía, que podrían ser de aplicación en este campo.[Résumé] Il s'exposent les bases méthodologiques que 1es auteur s app1i quen t á 1I investigation et évaluation de gisements des ardoises pour couvertures, prisses autant de sa propre expérience que de la maigre bibliographie disponible sur le sujeto Les facteurs que controlent la qualité des gisements de la materie prime sont trois types: Litoestratiphiques, estructurales et metamórphiques. lIs se réfléchent sur une serp€ de parámetres que sont ceux que normalement s'evaluent sur le champ. L' investigation utilise les téc niques básiques, adaptées aux peculiarités de Celle-lá se mene á bien en trois phases. une des phases on presenten des exemples. On remarque aussi quelques nouvelles técniques 'investigation cherchées sur la bibliographie, qu'il pouvaient etre d'aplication sur ce champ

    Paraganglioma of Prostatic Origin

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    Introduction Paragangliomas are usually benign tumors arising from chromaffin cells located outside the adrenal gland. Prostatic paraganglioma is an unusual entity in adult patients, with only 10 cases reported in the medical literature. Case Report A 34-year-old male with a history of chronic prostatitis consulted for perineal pain. On digital rectal examination the prostate was enlarged and firm, without nodules. The PSA level was 0.8 ng/mL and the catecholamines in the urine were elevated. On ultrasound a retrovesical 9 cm mass of undetermined origin measuring was present. A PET-CT scan showed a pelvic lesion measuring 9 cm with moderate increase in glucidic metabolism localized in the area of the prostate. A biopsy of the prostate revealed a neuroendocrine tumor, possibly a prostatic paraganglioma. A body scintigraphy with MIBG I-123 ruled out the presence of metastases or multifocal tumor. A radical prostatectomy with excision of the pelvic mass was performed under adrenergic blockade. One year after surgery the patient is asymptomatic and disease free. Discussion/Conclusions Prostatic paraganglioma is a rare, usually benign tumor, which should be considered in the differential diagnosis of prostate tumors in young males. Its diagnosis is based on the determination of catecholamine in blood and 24-hour urine and in imaging studies principally scintigraphy with MIBG I-123. Diagnostic confirmation is by histopathological study. The treatment consists of radical resection under adrenergic blockade and volume expansion. Given the limited number of cases reported, it is difficult to establish prognostic factors. Malignancy is defined by clinical criteria, and requires life long follow-up

    Comparative Analysis of Turbulence Models for Thermal-Hydraulic Simulations in Aqueous Homogeneous Reactors

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    This article presents a comparative study of various turbulence models applied in the context of thermal-hydraulic simulations for liquid fuel reactors, specifically Aqueous Homogeneous Reactors (AHR) using Computational Fluid Dynamics. The objective was to assess the suitability of the turbulence models by comparing their results with data obtained from Large Eddy Simulation (LES). For that purpose, was compared the flow behavior predicted using the k-ε, SST, GEKO, DES, SBES, and LES turbulence models. The calculations were carried out in a simplified computational model derived from a pre-existing three-dimensional AHR conceptual design. By utilizing this simplified model, the study aimed to focus on the computational differences between the turbulence models, while minimizing the influence of other factors. The calculation results revealed that the k-ε model exhibited significant discrepancies with the LES, with relative differences for the fuel solution maximum temperature reaching up to 75 %. Among the remaining RANS models, the Shear Stress Transport (SST) model demonstrated the best compromise between accuracy and computational efficiency, with differences below 5 % and requiring only 1/5th of the time, compared to the LES model.  The Scale-Resolving Simulation (SRS) models,DES and SBES, provided a more comprehensive description of flow behavior and results closer to LES, albeit with higher computational demands. Between these two models, only the DES model exhibited relative differences below or equal to     1 % compared to the LES model for the studied thermohydraulic parameters
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