One-Dimensional Mathematical Model for Kayak Propulsion

[EN] The displacement of a sprint kayak can be described by a one-dimensional mathematical model, which, in its simplest case, is analogous to the free-fall problem with quadratic drag and constant propulsion. To describe realistic cases, it is necessary to introduce a propulsion capable of reproducing the characteristics of the kayak stroke, including periodicity, average force and effects of stroke frequency, among others. Addressing the problem in terms of a Fourier series allows us to separate the equation into two parts, one of which is equivalent to the constant propulsion case and results in an asymptotic expression, while the second accounts for the periodic contributions. This approach allows us to solve several cases of interest: to propose a quadrature rule for the asymptotic part that allows fast estimations; to compare results with the literature; and finally to propose a general mathematical method for this problem which could help to understand some key strategies in the kayak race.S

Aplicaciones del Álgebra Lineal: prácticas de Matlab.

[ES] Colección de problemas resueltos y enunciados usados en las prácticas de Matlab de la asignatura de Álgebra Lineal de los grados de Ingeniería Forestal e Ingeniería Geomática de la Universidad de León

Estudio mediante dinámica molecular del efecto de la radiación e isótopos de H en diamante para su aplicación en fusión

Las recientes mejoras en la síntesis de Diamante artificial han logrado cristales de mayor tamaño, propiedades optimizadas y en muchos casos superiores a sus variantes naturales. Con ello, los cristales sintéticos de Diamante, pasan a ser una alternativa seria en aplicaciones de Fusión Nuclear. Algunas de las propiedades deseables para dichas aplicaciones son especialmente notables en Diamante, entre otras su conductividad térmica o su amplio rango de transparencia electromagnética. Sin embargo, el conocimiento acumulado acerca de su comportamiento bajo radiación, o más concretamente bajo las condiciones radiactivas de Fusión, es todavía limitado. En aplicaciones de Fusión nuclear, es imprescindible conocer el efecto de la radiación neutrónica y la interacción del material con Hidrógeno, sus isótopos y otros elementos ligeros propios de los plasmas de Fusión. No nos consta una bibliografía extensa acerca del daño por radiación en Diamante, existen estudios poco concluyentes acerca de la energía umbral de desplazamiento, se ha estudiado la grafitización o amorfización y tópicos tales como la implantación o el daño por bombardeo electrónico, iónico o gamma, pero no se han encontrado trabajos previos a esta tesis en cascadas de desplazamientos 1 y, como veremos, apenas unos pocos trabajos utilizan la técnica de la Dinámica Molecular en estudios de daño por radiación en este material. La interacción del Hidrógeno en la red de Diamante sí ha sido extensamente estudiada, se conocen multitud de líneas de absorción relacionadas con su presencia, se ha estudiado su difusión mediante técnicas experimentales y existen descripciones atomísticas de los sitios de equilibrio en la red de Diamante, aislado o formando parte de agregados..

La tecnología NFC y sus aplicaciones en un entorno universitario

Near Field Communication (NFC) es una tecnología basada en identificación por radiofrecuencia que permite la comunicación inalámbrica entre dispositivos, intercambiando información a gran velocidad, lo que abre un amplio abanico de aplicaciones atractivas para el usuario, (por ejemplo, pagos de compras, acceso a contenidos, comunicación peer to peer, etc). NFC entró con fuerza en la industria de las comunicaciones móviles hace unos años y, aunque parecía ser una alternativa seria a Bluetooth e IrDa, muy pocos fabricantes fueron los que se lanzaron al mercado de NFC, lo que provocó que dicha tecnología no terminara de despegar. Este año, la multinacional Nokia ha anunciado que a partir del 2011 todos sus Smartphones contarán con soporte NFC. Esta noticia ha disparado de nuevo el interés por NFC y sus múltiples aplicaciones. En este artículo se presenta un estudio de la tecnología NFC, sus fundamentos, principales características y aplicaciones. Además se describen las líneas actuales de trabajo del Grupo de Ingeniería Telemática en el ámbito de las comunicaciones NFC, que se centran en la implementación de NFC en entornos universitarios.Programa de Ayudas a Grupos de Excelencia de la Región de Murcia, Fundación Séneca, Agencia de Ciencia y Tecnología de la región de Murcia (Plan Regional de Ciencia y Tecnología 2007/2010

Registros inusuales de aves en la hoya de Loja, Andes sur del Ecuador

Presentamos datos actualizados sobre la distribución de 20 especies de aves del Ecuador, 16 de estas registradas por primera ocasión dentro de la hoya de Loja, valle inter-Andino del sur del país: Podilymbus podiceps, Phalacrocorax brasilianus, Butorides striata, Bubulcus ibis, Ardea alba, Chondrohierax uncinatus, Rupornis magnirostris, Gallinula galeata, Megascops roboratus, Megaceryle torquata, Aulacorhynchus prasinus, Forpus coelestis, Psittacara erythrogenys, Grallaria guatimalensis, Pitangus sulphuratus, Pachyramphus homochrous, Turdus reevei, Sporophila corvina, Rhynchospiza stolzmanni, y Cardellina canadensis. Únicamente P. brasilianus, B. striata, B. ibis y G. galeata han sido registradas previamente en el área de estudio, sin embargo, para estas especies se presentan nuevas localidades de registro, todas asociadas a pequeñas lagunas existentes alrededor de la ciudad de Loja. Esta información permite incrementar el conocimiento sobre la distribución geográfica y altitudinal de estas aves en el sur de Ecuador

Conversion from immediate-release tacrolimus to prolonged-release tacrolimus in stable heart transplant patients: a retrospective study

[Abstract] Background Lifelong adherence with post-transplant immunosuppression is challenging, with nonadherence associated with greater acute rejection (AR) risk. Methods This retrospective study evaluated conversion from immediate-release tacrolimus (IRT) to prolonged-release tacrolimus (PRT), between January 2008 and December 2012 in stable adult heart transplant recipients. Cumulative incidence rate (IR) of AR and infection pre- and postconversion, safety, tacrolimus dose and trough levels, concomitant immunosuppression, and PRT discontinuation were analyzed (intention-to-treat population). Results Overall, 467 patients (mean age, 59.3 [SD, 13.3] years) converted to PRT at 5.1 (SD, 4.9) years post transplant and were followed for 3.4 (SD, 1.5) years. During the 6 months post conversion, 5 patients (1.1%; 95% CI, 0.35%–2.48%) had an AR episode and IR was 2.2/100 patient-years (95% CI, 0.91–5.26). Incidence of rejection preconversion varied by time from transplant to conversion. Infection IR was similar post- and preconversion (9.2/100 patient-years [95% CI, 7.4–11.3] vs 10.6/100 patient-years [95% CI, 8.8–12.3], respectively; P = .20). Safety variables remained similar post conversion. The IR of mortality/graft loss was 2.3/100 patient-years (95% CI, 1.7–3.1). Conclusions Conversion from IRT to PRT in heart transplant recipients in Spain was associated with no new safety concerns and appropriate immunosuppressive effectiveness

Influence of Gender in Advanced Heart Failure Therapies and Outcome Following Transplantation

Biological differences between males and females change the course of different diseases and affect therapeutic measures' responses. Heart failure is not an exception to these differences. Women account for a minority of patients on the waiting list for heart transplantation or other advanced heart failure therapies. The reason for this under-representation is unknown. Men have a worse cardiovascular risk profile and suffer more often from ischemic heart disease. Conversely, transplanted women are younger and more frequently have non-ischemic cardiac disorders. Women's poorer survival on the waiting list for heart transplantation has been previously described, but this trend has been corrected in recent years. The use of ventricular assist devices in women is progressively increasing, with comparable results than in men. The indication rate for a heart transplant in women (number of women on the waiting list for millions of habitants) has remained unchanged over the past 25 years. Long-term results of heart transplants are equal for both men and women. We have analyzed the data of a national registry of heart transplant patients to look for possible future directions for a more in-depth study of sex differences in this area. We have analyzed 1-year outcomes of heart transplant recipients. We found similar results in men and women and no sex-related interactions with any of the factors related to survival or differences in death causes between men and women. We should keep trying to approach sex differences in prospective studies to confirm if they deserve a different approach, which is not supported by current evidence

Preoperative toxoplasma gondii serostatus does not affect long-term survival of cardiac transplant recipients: analysis of the Spanish Heart Transplantation Registry

[Abstract] Background. It's unclear whether pre-transplant T. gondii seropositivity is associated with impaired survival in heart transplant recipients. Objectives. To test the above-mentioned hypothesis in the Spanish Heart Transplantation Registry. Methods. Post-transplant outcomes of 4048 patients aged > 16 years who underwent first, single-organ heart transplantation in 17 Spanish institutions from 1984 to 2014 were studied. Long-term post-transplant survival and survival free of cardiac death or retransplantation of 2434 (60%) T. gondii seropositive recipients and 1614 (40%) T. gondii seronegative recipients were compared. Results. T. gondii seropositive recipients were older, had higher body mass index, and presented higher prevalence of hypertension, hypercholesterolemia, COPD and Cytomegalovirus seropositivity than T. gondii seronegative recipients. In univariable analysis, pre-transplant T. gondii seropositivity was associated with increased post-transplant all-cause mortality (non-adjusted HR 1.15; 95% CI 1.04–1.26). However, this effect was no longer statistically significant after multivariable adjustment by recipient's age and sex (adjusted HR 1.01, 95% CI 0.92–1.11). Extended multivariable adjustment by other potential confounders showed similar results (adjusted HR 0.99, 95% CI 0.89–1.11). T. gondii seropositivity had no significant effect on the composite outcome cardiac death or retransplantation (non-adjusted HR 1.08, 95% CI 0.95–1.24, p = 0.235). The distribution of the causes of death was comparable in T. gondii seropositive and T. gondii seronegative recipients. No statistically significant impact of donor's T. gondii serostatus or donor-recipient T. gondii serostatus matching on post-transplant survival was observed. Conclusions. Our analysis did not show a significant independent effect of preoperative T. gondii serostatus on long-term outcomes after heart transplantation

Morbid liver manifestations are intrinsically bound to metabolic syndrome and nutrient intake based on a machine-learning cluster analysis

Metabolic syndrome (MetS) is one of the most important medical problems around the world. Identification of patient ' s singular characteristic could help to reduce the clinical impact and facilitate individualized management. This study aimed to categorize MetS patients using phenotypical and clinical variables habitually collected during health check-ups of individuals considered to have high cardiovascular risk. The selected markers to categorize MetS participants included anthropometric variables as well as clinical data, biochemical parameters and prescribed pharmacological treatment. An exploratory factor analysis was carried out with a subsequent hierarchical cluster analysis using the z-scores from factor analysis. The first step identified three different factors. The first was determined by hypercholesterolemia and associated treatments, the second factor exhibited glycemic disorders and accompanying treatments and the third factor was characterized by hepatic enzymes. Subsequently four clusters of patients were identified, where cluster 1 was characterized by glucose disorders and treatments, cluster 2 presented mild MetS, cluster 3 presented exacerbated levels of hepatic enzymes and cluster 4 highlighted cholesterol and its associated treatments Interestingly, the liver status related cluster was characterized by higher protein consumption and cluster 4 with low polyunsaturated fatty acid intake. This research emphasized the potential clinical relevance of hepatic impairments in addition to MetS traditional characterization for precision and personalized management of MetS patients

Role of NAFLD on the Health Related QoL Response to Lifestyle in Patients With Metabolic Syndrome: The PREDIMED Plus Cohort

ObjectiveTo evaluate the effect of Non-alcoholic fatty liver disease (NAFLD) status in the impact of lifestyle over Health-related quality of life (HRQoL) in patients with metabolic syndrome (MetS). MethodsBaseline and 1 year follow up data from the PREDIMED-plus cohort (men and women, 55-75 years old with overweight/obesity and MetS) were studied. Adherence to an energy-restricted Mediterranean Diet (er-MeDiet) and Physical Activity (PA) were assessed with a validated screeners. Hepatic steatosis index (HSI) was implemented to evaluate NAFLD while the SF-36 questionnaire provided HRQoL evaluation. Statistical analyses were performed to evaluate the influence of baseline NAFLD on HRQoL as affected by lifestyle during 1 year of follow up. ResultsData from 5205 patients with mean age of 65 years and a 48% of female participants. Adjusted linear multivariate mixed regression models showed that patients with lower probability of NAFLD (HSI < 36 points) were more responsive to er-MeDiet (beta 0.64 vs beta 0.05 per er-MeDiet adherence point, p< 0.01) and PA (beta 0.05 vs beta 0.01 per MET-h/week, p = 0.001) than those with high probability for NAFLD in terms Physical SF-36 summary in the 1 year follow up. 10 points of er-MeDiet adherence and 50 MET-h/week were thresholds for a beneficial effect of lifestyle on HRQoL physical domain in patients with lower probability of NAFLD. ConclusionThe evaluation of NAFLD by the HSI index in patients with MetS might identify subjects with different prospective sensitivity to lifestyle changes in terms of physical HRQoL (http://www.isrctn.com/ISRCTN89898870)