Barquero-Perez O.,Rey Juan Carlos University |
Figuera C.,Rey Juan Carlos University |
Goya-Esteban R.,Rey Juan Carlos University |
Mora-Jimenez I.,Rey Juan Carlos University |
And 10 more authors.
IEEE Transactions on Biomedical Engineering | Year: 2017
Objective: Heart rate turbulence (HRT) has been successfully explored for cardiac risk stratification. While HRT is known to be influenced by the heart rate (HR) and the coupling interval (CI), nonconcordant results have been reported on how the CI influences HRT. The purpose of this study is to investigate HRT changes in terms of CI and HR by means of an especially designed protocol. Methods: A dataset was acquired from 11 patients with structurally normal hearts for which CI was altered by different pacing trains and HR by isoproterenol during electrophysiological study (EPS). The protocol was designed so that, first, the effect of HR changes on HRT and, second, the combined effect of HR and CI could be explored. As a complement to the EPS dataset, a database of 24-h Holters from 61 acute myocardial infarction (AMI) patients was studied for the purpose of assessing risk. Data analysis was performed by using different nonlinear ridge regression models, and the relevance of model variables was assessed using resampling methods. The EPS subjects, with and without isoproterenol, were analyzed separately. Results: The proposed nonlinear regression models were found to account for the influence of HR and CI on HRT, both in patients undergoing EPS without isoproterenol and in low-risk AMI patients, whereas this influence was absent in high-risk AMI patients. Moreover, model coefficients related to CI were not statistically significant, p > 0.05, on EPS subjects with isoproterenol. Conclusion: The observed relationship between CI and HRT, being in agreement with the baroreflex hypothesis, was statistically significant (p < 0.05), when decoupling the effect of HR and normalizing the CI by the HR. Significance: The results of this study can help to provide new risk indicators that take into account physiological influence on HRT, as well as to model how this influence changes in different cardiac conditions. © 2016 IEEE.
Mendiola J.,University of Murcia |
Moreno J.M.,Technical University of Cartagena |
Roca M.,University of Murcia |
Vergara-Jurez N.,Technical University of Cartagena |
And 9 more authors.
Environmental Health: A Global Access Science Source | Year: 2011
Background: Animal studies have shown the reproductive toxicity of a number of heavy metals. Very few human observational studies have analyzed the relationship between male reproductive function and heavy metal concentrations in diverse biological fluids. Methods. The current study assessed the associations between seminal and hormonal parameters and the concentration of the 3 most frequent heavy metal toxicants (lead, cadmium and mercury) in three different body fluids. Sixty one men attending infertility clinics that participated in a case-control study to explore the role of environmental toxins and lifestyles on male infertility were analyzed. Concentration of lead, cadmium and mercury were measured in blood and seminal plasma and whole blood using anodic stripping voltammetry and atomic absorption spectrophotometry. Serum samples were analyzed for follicle-stimulating hormone, luteinizing hormone and testosterone. Semen analyses were performed according to World Health Organization criteria. Mann-Whitney test and Spearman's rank correlations were used for unadjusted analyses. Multiple linear regression models were performed controlling for age, body mass index and number of cigarettes per day. Results: There were no significant differences between cases and controls in the concentrations of heavy metals in any of the three body fluids. In multivariate analyses using all subjects no significant associations were found between serum hormone levels and metal concentrations. However there was a significant positive association between the percentage of immotile sperms and seminal plasma levels of lead and cadmium. Conclusions: Our results suggest that the presence of lead and cadmium in the reproductive tract of men may be related to a moderate alteration of their seminal parameters. © 2011 Mendiola et al; licensee BioMed Central Ltd.
Martinez-Rach M.O.,University Miguel Hernández |
De Silva D.,University of Surrey |
Fernando A.,University of Surrey |
Arachchi H.K.,University of Surrey |
And 2 more authors.
Digest of Technical Papers - IEEE International Conference on Consumer Electronics | Year: 2012
Depth maps, which aid the virtual view generation process in Depth Image Based Rendering (DIBR) applications in 3D video, are generally piecewise smooth images with sharp depth discontinuities. Compression artifacts that occur along the depth discontinuities often lead to poor quality of generated virtual views. In line with the importance of depth discontinuities towards view generation, we propose a non-uniform quantization method for wavelet based encoding of depth maps. Average rendering quality improvements of up to 0.8dB could be achieved. © 2012 IEEE.
Serracn J.R.,Technological University of Panama |
Puglisi L.J.,Technical University of Madrid |
Saltaren R.,Technical University of Madrid |
Ejarque G.,Technical University of Madrid |
And 2 more authors.
Robotics and Autonomous Systems | Year: 2012
This paper presents the development of a new parallel robot designed for helping with bone milling surgeries. The robot is a small modular wrist with 2 active degrees of freedom, and it is proposed to be used as an orientation device located at the end of a robotic arm designed for bone milling processes. A generic 2UP̄S-1S kinematic geometry is proposed for this device. This first article shows the developments on the workspace optimization and the analysis of the force field required to complete a reconstruction of the inferior jawbone. The singularities of the mechanism are analyzed, and the actuator selection is justified with the torque requirements and the study of the force space. The results obtained by the simulations allow building a first prototype using linear motors. Bone milling experiment video is shown as additional material. © 2012 Elsevier B.V. All rights reserved.
Zamora B.,Technical University of Cartagena |
Kaisere A.S.,Technical University of Cartagena |
Kling U.,Technical University of Cartagena |
Lucas M.,Miguel Hernndez University |
Ruiz J.,Miguel Hernndez University
Journal of Fluids Engineering, Transactions of the ASME | Year: 2011
This work presents an uncertainty study in the numerical simulation of the air-water droplet motion through three types of drift eliminators using the grid convergence index (GCI) method. The analysis of independence of the results with respect to the fineness of mesh is developed with special emphasis on the influence of the nondimensional sub-layer scaled distance. The coefficient of pressure drop and the droplet collection efficiency are numerically calculated. It may be concluded that using the GCI method leads to reliable numerical results, but it is also necessary to establish a sufficiently fine mesh near the walls. © 2011 American Society of Mechanical Engineers.