Persona: Rodríguez Pérez, Daniel
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drodriguez@ccia.uned.es
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0000-0001-5811-4172
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Rodríguez Pérez
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Daniel
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Publicación Colaboraciones en Física : luz e imagen médica : tomografía óptica(Universidad Nacional de Educación a Distancia (España). Facultad de Ciencias, 2010-01-01) Sotolongo, Óscar; Vaquero, Juan José; Antoranz Callejo, José Carlos; Rodríguez Pérez, DanielPublicación How Far Can We Classify Macroalgae Remotely? An Example Using a New Spectral Library of Species from the South West Atlantic (Argentine Patagonia)(MDPI, 2020-11-26) Olmedo Masat, Olga Magalí; Raffo, María Paula; Rodríguez Pérez, Daniel; Arijón, Marianela; Sánchez Carnero, NoelaMacroalgae have attracted the interest of remote sensing as targets to study coastal marine ecosystems because of their key ecological role. The goal of this paper is to analyze a new spectral library, including 28 macroalgae from the South-West Atlantic coast, in order to assess its use in hyperspectral remote sensing. The library includes species collected in the Atlantic Patagonian coast (Argentina) with representatives of brown, red, and green algae, being 22 of the species included in a spectral library for the first time. The spectra of these main groups are described, and the intraspecific variability is also assessed, considering kelp differentiated tissues and depth range, discussing them from the point of view of their effects on spectral features. A classification and an independent component analysis using the spectral range and simulated bands of two state-of-the-art drone-borne hyperspectral sensors were performed. The results show spectral features and clusters identifying further algae taxonomic groups, showing the potential applications of this spectral library for drone-based mapping of this ecological and economical asset of our coastal marine ecosystems.Publicación Validation of noninvasive indices of right ventricular diastolic function. Simultaneous echocardiography and pressure-volume catheterization studies(Springer, 2025-07-09) Pérez del Villar, Candelas; Prieto Arévalo, Raquel; García Carreño, Jorge; Martínez-Legazpi Aguilo, Pablo; Rodríguez Pérez, Daniel; Benito, Yolanda; Delgado Montero, Antonia; Antoranz Callejo, José Carlos; Desco Menéndez, Mª del Mar; Herrera Flores, Cristian; Corisco Beltrán, Rafael; Fernández Avilés, Francisco; Bermejo, Javier; Instituto de Salud Carlos III; Gerencia Regional de Salud de Castilla y León; EU – European Regional Development Fund; Instituto de Investigación Sanitaria Gregorio MarañonBackground The reliability of the recommended echocardiographic methods for assessing RV diastolic function has been questioned. We aimed to validate noninvasive indices of RV diastolic function, derived from tricuspid Doppler and myocardial deformation metrics, against intrinsic diastolic chamber properties and filling pressures. Methods We obtained simultaneous high-fidelity pressure-volume loops and echocardiographic data in separate animal and clinical settings: (1) a porcine model of acute hemodynamic interventions (n = 13), and (2) patients with Fallot tetralogy and pulmonary hypertension (n = 9). These designs allow for within- and between-subject validation. From the PV loops data, we obtained the reference values of RV stiffness (S+), elastic recoil (S−) and relaxation (τ) constants, as well as the contribution of passive properties to instantaneous diastolic pressures. Results In the animal setting, only the tricuspid E/A ratio and e’ velocity weakly correlated with S+ (Rrm:0.36 and 0.28 respectively, p < 0.01 for both). In the clinical group, no correlation was found between the echocardiographic indices and the intrinsic diastolic properties. Isovolumic relaxation time and early diastolic global strain-rate (GSR) correlated with mean right atrial pressure (RAP) (Spearman r: -0.73 and 0.85, respectively, p < 0.05 for both). E/e’ and E/GSR ratio were not associated with RAP. Tricuspid e’ and GSR negatively correlated with passive pressure component (only due to) at valve opening (Rrm -0.27 and − 0.33, respectively, p < 0.01 for both). Conclusions Recommended echocardiographic indices of RV diastolic function do not reflect intrinsic RV diastolic properties. Therefore, the application of these indices for inferring RV diastolic function and filling pressures is limited.Publicación Fast and low-cost method for VBES bathymetry generation in coastal areas(Elsevier, 2012-12-01) Sánchez Carnero, Noela; Aceña, Sara; Rodríguez Pérez, Daniel; Couñago, Elena; Fraile, Pablo; Freire, JuanSea floor topography is key information in coastal area management. Nowadays, LiDAR and multibeam technologies provide accurate bathymetries in those areas; however these methodologies are yet too expensive for small customers (fishermen associations, small research groups) willing to keep a periodic surveillance of environmental resources. In this paper, we analyse a simple methodology for vertical beam echosounder (VBES) bathymetric data acquisition and postprocessing, using low-cost means and free customizable tools such as ECOSONS and gvSIG (that is compared with industry standard ArcGIS). Echosounder data was filtered, resampled and, interpolated (using kriging or radial basis functions). Moreover, the presented methodology includes two data correction processes: Monte Carlo simulation, used to reduce GPS errors, and manually applied bathymetric line transformations, both improving the obtained results. As an example, we present the bathymetry of the Ría de Cedeira (Galicia, NW Spain), a good testbed area for coastal bathymetry methodologies given its extension and rich topography. The statistical analysis, performed by direct ground-truthing, rendered an upper bound of 1.7 m error, at 95% confidence level, and 0.7 m r.m.s. (cross-validation provided 30 cm and 25 cm, respectively). The methodology presented is fast and easy to implement, accurate outside transects (accuracy can be estimated), and can be used as a low-cost periodical monitoring method.Publicación Exploiting oceanographic satellite data to study the small scale coastal dynamics in a NE Atlantic open embayment(Elsevier, 2011-03-22) Sánchez Carnero, Noela; Couñago, Elena; Rodríguez Pérez, Daniel; Freire, JuanAn approach to the processing and analysis of oceanographic satellite data is presented suitable for its use in coastal areas. Satellite images of a small (300 km2) open embayment in the NW of the Iberian Peninsula (Seno de Corcubión) are used to study a decade of time series of three important oceanographic variables: sea surface temperature (SST), chlorophyll a concentration ([Chlo]) and turbidity (K490). Their interannual and seasonal trends, together with the regional variability, are assessed using a Generalized Linear Model (GLM). We identify seasonal upwelling–downwelling processes, on top of interannual trends that show that coastal dynamics is not directly driven by the oceanic trend. To study spatial patterns the study area was divided in subareas; these subareas show significant differences among them in seasonal as well as in interannual scales. Using this information, some oceanographic hypotheses were tested based on the statistical significance of the variable residual dependencies: a possible relationship between SST and turbidity (found to be not significant in the study area), and the presence of short-term upwelling events reported by other researchers in this geographical region (not found statistically significant either). A database and an oceanographic atlas summarizing all the information used in the analyses have been generated and can be freely visualized online and downloaded.Publicación Using vertical Sidescan Sonar as a tool for seagrass cartography(Elsevier, 2012-12-10) Sánchez Carnero, Noela; Rodríguez Pérez, Daniel; Couñago, Elena; Aceña, Sara; Freire, JuanAn acoustic method, a vertically oriented Sidescan Sonar (SSSv), is used to detect and map Posidonia oceanica meadows in the bay of Agua Amarga (SE of the Mediterranean coast of Spain). Sidescan sonar, among other active hydroacoustic techniques, has shown its ability to detect, map and monitor seagrass based on its acoustic backscatter; however, some limitations linked to its power based approach have been reported in the literature. Our method is based on the SSSv measurement of canopy height distribution, making the most use of the SSSv acoustic data and using existing algorithms as statistical mapping methods. The results show a spatially coherent and statistically consistent classification. The comparison with groundtruthing is difficult due to the steep variations in the seafloor cover found in the area of interest, nevertheless the validation is successful (proving low-order discrimination) in a zone with a large range of depth variations (0−25 m).Publicación Congresos, seminarios, reuniones científicas y cursos de verano: I Jornada de Física Médica de la UNED(Universidad Nacional de Educación a Distancia (España). Facultad de Ciencias, 2017-01-01) Rodríguez Pérez, DanielPublicación A sea bottom classification of the Robredo area in the 2 northern San Jorge Gulf (Argentina)(Springer, 2021-02-02) Sánzhez Carnero, Noela; Rodríguez Pérez, DanielBenthic habitats are primarily determined by the nature of the substrate (i.e., the type of sediment or rock) and by the bathymetry (e.g., light availability, current, or waves exposition) both determining the viability of infaunal organisms. In this sense multibeam (MB) echosounders provide more data about the sea bottom than any other acoustic technique. During the 2014 Argentine-Canadian survey of the RV Coriolis II in the Gulf of San Jorge, MB data were acquired in the area of Robredo, west of the Marine Protected Area (MPA) Parque Interjurisdiccional Marino Costero Patagonia Austral (PIMCPA, Patagonia, Argentine). Acoustic data were affected by acquisition artifacts, so an ad hoc algorithm was required to restore the data. Moreover, during the survey, dredge samples were also acquired where acoustic data suggested changes in substrate properties, and two later scientific surveys acquired video transects of the sea bottom that allowed also a basic classification. A non-supervised classification of the seabed was performed, using a subsampling and voting algorithm, with the acoustic and bathymetric data. The final classification is in agreement with groundtruthing (dredge samples and video transects), showing that bottom structure complexity leads to a meaningful picture of the sea bottom classes in the area. Our results reveal that Robredo has two subareas, one with a fine substrate (west) and another with a coarse substrate (east), the latter being also characterized by outcropping rock formations of marked relief. Despite the small spatial coverage of the survey, the resulting sea bottom classification presented in this paper has described, for the first time, some important features of the benthic geohabitats in the PIMCPA.Publicación Uncritical polarized groups: The impact of spreading fake news as fact in social networks(Elsevier, 2020-12) San Martín, Jesús; Drubi Vega, Fátima; Rodríguez Pérez, Daniel; Ministerio de Ciencia, Innovación y Universidades (España)The spread of ideas in online social networks is a crucial phenomenon to understand nowadays the proliferation of fake news and their impact in democracies. This makes necessary to use models that mimic the circulation of rumors. The law of large numbers as well as the probability distribution of contact groups allow us to construct a model with a minimum number of hypotheses. Moreover, we can analyze with this model the presence of very polarized groups of individuals (humans or bots) who spread a rumor as soon as they know about it. Given only the initial number of individuals who know any news, in a population connected by an instant messaging application, we first deduce from our model a simple function of time to study the rumor propagation. We then prove that the polarized groups can be detected and quantified from empirical data. Finally, we also predict the time required by any rumor to reach a fixed percentage of the populationPublicación A pulse-length correction to improve energy-based seabed classification in coastal areas(Elsevier, 2014-01-25) Rodríguez Pérez, Daniel; Sánchez Carnero, Noela; Freire, JuanSea bottom classification using echosounders is an active field of research, where many different methods (to define echo features or perform their statistical classification) have been proposed and tested. Here we propose a new echo correction method suitable for use in coastal waters, where large relative depth variations occur. The idea is based on scaling the pulse length with depth as suggested by Pouliquen (Preston et al., 2004. Proceedings of the Seventh European Conference on Underwater Acoustics, ECUA 2004), but instead of in real time, in postprocessing. We investigate, in particular, the benefits of this correction for a classification based on the energy integrals of first and second return echoes, relying on the correction to find an optimal definition for those energy integrals. The method is tested in a coastal area survey with substrates varying over small scales (less than 200 m) and with large relative changes in water depth (5–40 m and slopes of up to 0.2). We show that the unsupervised classification bears a good agreement with divers groundtruthing (85% agreement with a Cohen׳s kappa, κ=0.74 for a 4-class map) and with previous knowledge of the study area.