1,343 research outputs found

    LRD spectral analysis of multifractional functional time series on manifolds

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    This paper introduces the statistical analysis of Jacobi frequency varying Long Range Dependence (LRD) functional time series in connected and compact two-point homogeneous spaces. The convergence to zero, in the Hilbert-Schmidt operator norm, of the integrated bias of the periodogram operator is proved under alternative conditions to the ones considered in Ruiz-Medina (2022). Under this setting of conditions, weak-consistency of the minimum contrast parameter estimator of the LRD operator holds. The case where the projected manifold process can display Short Range Dependence (SRD) and LRD at different manifold scales is also analyzed. The estimation of the spectral density operator is addressed in this case. The performance of both estimation procedures is illustrated in the simulation study undertaken within the families of multifractionally integrated spherical functional autoregressive-moving average (SPHARMA) processes.Comment: 34 pages; 19 Figure

    Nanociència : l'important no rau en la noblesa

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    La nanociència avança dia a dia en el que és el seu camp amb més projecció: les nanopartícules metàl·liques (NPMs). Les excepcionals propietats físico-químiques que les caracteritzen fan possible les seves aplicacions electroquímiques. Aquestes però, poden veure's afectades degut a la tendència de les NPMs a agregar-se, perdent així, la seva forma original. Estabilitzant-les en matrius polimèriques, no només s'ha aconseguit controlar les seves mides i velocitat de creixement, sinó que també poden ser emmagatzemades en forma sòlida i líquida, gràcies a la solubilitat dels polímers. Aquestes aplicacions electroquímiques, tal i com s'explica en el següent article, es basen en l'ús de metalls nobles (partícules monometàl·liques), la qual cosa encareix molt el procés. D'aquí que un dels objectius sigui decréixer la quantitat d'aquests metalls -sense perdre la seva capacitat electrocatalítica- i preparar nanopartícules del tipus nucli-embolcall (bimetàl·liques). Aquestes posseeixen un nucli de metall econòmic recobert per un altre de noble, i han demostrat ser més estables en quant a mida i forma, a més de presentar una activitat electrocatalítica superior.La nanociencia avanza día a día en el que es su campo con más proyección: las nanopartículas metálicas (NPMs). Las excepcionales propiedades físico-químicas que las caracterizan hacen posible sus aplicaciones electroquímicas. Éstas, sin embargo, pueden verse afectadas debido a la tendencia de las NPMs a agregarse, perdiendo, así, su forma original. Estabilizándolas en matrices poliméricas, no sólo se ha conseguido controlar su tamaño y velocidad de crecimiento, sino que también pueden ser almacenadas en forma sólida y líquida, gracias a la solubilidad de los polímeros. Estas aplicaciones electroquímicas, tal como se explica en el siguiente artículo, se basan en el uso de metales nobles (partículas monometálicas), lo que encarece mucho el proceso. De aquí que uno de los objetivos sea disminuir la cantidad de estos metales -sin perder su capacidad electrocatalítica- y preparar nanopartículas del tipo núcleo-envoltorio (bimetálicas). Éstas poseen un núcleo de metal económico recubierto por otro que es noble, y han demostrado ser más estables en cuanto a tamaño y forma, además de presentar una actividad electrocatalítica superior, siempre y cuando se mantenga la misma cantidad de metal noble.The field of metallic nanoparticles (MNP), one of the nanoscience fields with most projection, advances daily. The exceptional characteristic physical and chemical properties of these particles make it possible to use them in electrochemical applications. However, this can be affected by the tendency of MNPs to group together and thus lose their original form. By stabilising the particles in polymeric matrices it is possible not only to control their size and speed of growth, but to store them in solid and liquid forms due to the solubility of polymers. As explained in the following article, noble metals (monometallic particles) are used in electrochemical applications, which make the process extremely expensive. The objective therefore is to reduce the quantity of noble metal used -without compromising electrocatalytic capacity -and add core-shell (bimetallic) nanoparticles. These possess a more economical metal core covered by a noble metal shell. They have been proved to be more stable in both size and shape, and display greater electrocatalytic activity

    Evolution of residual stresses induced by machining in a Nickel based alloy under static loading at room temperature

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    Tensile residual stresses are very often generated on the surface when machining nickel alloys. In order to determine their influence on the final mechanical behaviour of the component residual stress stability should be considered. In the present work the evolution of residual stresses induced by machining in Inconel 718 under static loading at room temperature has been studied. An Inconel 718 disc has been face turned and specimens for tensile tests have been extracted from the disc. Then surface residual stresses have been measured by X-ray diffraction for initial state and different loading levels. Finally, a finite element model has been fitted to experimental results and the study has been extended for more loading conditions. For the studied case, it has been observed that tensile residual stresses remain stable when applying elastic loads but they increase at higher loads close to the yield stress of the material

    Prevalencia de hipotensión ortostática en ancianos hipertensos tratados en atención primaria

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    ObjetivoConocer la prevalencia de hipotensión ortostática (HO) y los factores asociados en ancianos hipertensos tratados en atención primaria (AP).DiseñoEstudio descriptivo, transversal.EmplazamientoCentro de Salud La Marina (centro urbano en Santander).PacientesUna muestra aleatoria de 295 pacientes de 65 o más años atendidos regularmente por presentar hipertensión arterial (HTA).Mediciones y resultados principalesSe han obtenido cifras de presión arterial (PA) en sedestación y en bipedestación. La definición de HO utilizada ha sido: disminución de 20 mmHg o más en la PA sistólica (PAS) o de 10 mmHg o más en la PA diastólica (PAD), tras 1 o 5 minutos de bipedestación. También se han recogido datos sobre enfermedades asociadas, síntomas en bipedestación, medicación utilizada, hábitos de los pacientes y resultados de otras exploraciones clínicas. La prevalencia global encontrada de HO fue del 14,6%. La prevalencia de HO sistólica tras un minuto (HO-S1) y tras 5 minutos (HO-S5) de bipedestación ha sido del 5,8% en ambas, y la de HO diastólica del 5,1% tras un minuto (HO-D1) y del 4,1% tras 5 minutos (HO-D5) de bipedestación. En el análisis de regresión logística se encontró una asociación entre la existencia de HO global y la mayor elevación de la PA sistólica inicial, la presencia de síntomas de intolerancia ortostática (aunque sólo un 25,6% de los pacientes con HO presentaba síntomas) y el hábito tabáquico. Asimismo, se encontró una asociación con el uso de bloqueadores beta y antagonistas del calcio (diferentes de las dihidropiridinas) y la existencia de HO al minuto de bipedestación, y entre el consumo de tabaco y la HO a los 5 minutos de bipedestación.ConclusionesLa prevalencia detectada es alta y justifica la búsqueda sistemática de HO en los pacientes ancianos que son tratados de HTA en AP. La existencia de síntomas con el ortostatismo se relaciona con una mayor prevalencia de HO, pero sólo los presentó uno de cada 4 pacientes con HO. El consumo de tabaco podría estar relacionado con la presencia de HO, así como el uso de bloqueadores beta y antagonistas del calcio (diferentes de las dihidropiridinas).ObjectiveTo find the prevalence of orthostatic hypotension (OH) and associated factors in elderly hypertensive patients in a primary care setting.DesignDescriptive cross-sectional study.SettingLa Marina Health Centre (an urban centre in Santander).PatientsA random sample of 295 patients aged 65 years or older regularly assisted from hypertension.Measurements and main resultsMeasurements of sitting and standing blood pressure were obtained. Orthostatic hypotension was defined as 20 mmHg or greater decrease in systolic or 10 mmHg or greater decrease in diastolic blood pressure after 1-minute or 5-minute standing. Associated diseases, symptoms upon standing, medication use, habits and other clinical assessments were also recorded. The prevalence of OH was 14.6%. The prevalence of systolic OH after 1-minute (OH-S1) and after 5-minute (OH-S5) standing was 5.8% in both, and the diastolic OH was 5.1% after 1-minute (OH-D1) and 4.1% after 5-minute (OH-D5) standing. By logistic regression analysis, association between higher level of systolic blood pressure and global OH was found, also with the presence of orthostatic intolerance symptoms (although only 25.6% of the patients with OH showed symptoms) and smoking. Beta-blockers and calcium channel blockers (different from dihydropyridines) use was associated with OH after 1-minute standing and smoking with OH after 5-minute standing.ConclusionsThe detected prevalence is high and justifies the case finding of OH in elderly hypertensive patients in primary care. The symptoms of orthostatic intolerance are correlated with OH, but only 1 out of 4 patients showed symptoms. Smoking could be related with OH, so beta-blockers and calcium channel blockers (different from dihydropyridines) use

    Specific Parameter-Free Global Optimization to Speed Up Setting and Avoid Factors Interactions

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    Meta-heuristics utilizing numerous parameters are more complicated than meta-heuristics with a couple of parameters for various reasons. In essence, the effort expected to tune the strategy-particular parameters is far more prominent as the quantity of parameters increases and furthermore, complex algorithms are liable for the presence of further parameter interactions. Jaya meta-heuristic does not involve any strategy-specific parameters and is a one-stage technique. It has demonstrated its effectiveness compared to major types of meta-heuristics and it introduces various points of interest, such as its easy deployment and set-up in industrial applications and its low complexity to be studied. In this work, a new meta-heuristic, Enhanced Jaya (EJaya) is proposed to overcome the inconsistency of Jaya in diverse situations, introducing coherent attraction and repulsion movements and restrained intensity for flight. Comparative results of EJaya in a set of benchmark problems including statistical tests show that it is feasible to increase the accuracy, scalability and exploitation capability of Jaya while keeping its specific parameter-free feature. EJaya is especially suitable for a priori undefined characteristics optimization functions or applications where the set-up time of the optimization process is critical and parameters tuning and interactions must be avoided

    APE Results of Hadron Masses in Full QCD Simulations

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    We present numerical results obtained in full QCD with 2 flavors of Wilson fermions. We discuss the relation between the phase of Polyakov loops and the {\bf sea} quarks boundary conditions. We report preliminary results about the HMC autocorrelation of the hadronic masses, on a 163×3216^3 \times 32 lattice volume, at β=5.55\beta=5.55 with ksea=0.1570k_{sea}=0.1570.Comment: 3 pages, compressed ps-file (uufiles), Contribution to Lattice 9

    Glycogen synthase in mantle tissue of Mytilus galloprovincialis Lamarck, 1819

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    Glycogen synthase (GS) from Mytilus galloprovincialis Lamarck, 1819 mantle tissue is primarily in G6P-dependent form, whose activity is four times that of the G6P-independent form. Both forms present higher activity to pH: 7, but the D-form mantains 60 % of its maximum activity at extreme pH values, whereas that of the I-form drops to 25 %. The optimum temperature is 30-35 ºC for both forms, but the I-form is more stable between 30 and 40 ºC. Kinetic data on both enzymatic forms indicate the existence of cooperative effects with regard to the substrate and effector. The I-form affinity constant for the substrate UDPG is 1.9-2.3 mM and that of the D-form is 0.9-1.3 mM. Moreover, the D-form shows an activation constant for the efector G6P of 5.2-5.6 mM.La enzima glucógeno sintasa del tejido del manto de Mytilus galloprovincialis Lamarck, 1819 se encuentra principalmente en su forma dependiente (D) de G6P, con una actividad cuatro veces mayor que la forma independiente (I) de G6P. Ambas formas presentan la mayor actividad a pH:7, pero la forma D mantiene el 60 % de su actividad a valores extremos de pH, donde la forma I disminuye la suya al 25 %. La temperatura óptima está entre 30 y 35 ºC en ambos casos, pero la forma I es más estable entre 30 y 40 ºC. Los datos cinéticos de ambas formas enzimáticas indican la existencia de efectos cooperativos respecto al sustrato y el efector. La constante de afinidad de la forma I para el sustrato UDPG es 1,9-2,3 mM y la de la D es 0,9-1,3 mM. La forma D muestra, además, una constante de activación de 5,2-5,6 mM para el efector G6P.Instituto Español de Oceanografí
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