A Simple RVoG Test for PolInSAR Data

In this paper, we present a simple algorithm for assessing the validity of the RVoG model for PolInSAR-based inversion techniques. This approach makes use of two important features characterizing a homogeneous random volume over a ground surface, i.e., the independence on polarization states of wave propagation through the volume and the structure of the polarimetric interferometric coherency matrix. These two features have led to two different methods proposed in the literature for retrieving the topographic phase within natural covers, i.e., the well-known line fitting procedure and the observation of the (1, 2) element of the polarimetric interferometric coherency matrix. We show that differences between outputs from both approaches can be interpreted in terms of the PolInSAR modeling based on the Freeman-Durden concept, and this leads to the definition of a RVoG/non-RVoG test. The algorithm is tested with both indoor and airborne data over agricultural and tropical forest areas.

3D model reconstruction using neural gas accelerated on GPU

In this work, we propose the use of the neural gas (NG), a neural network that uses an unsupervised Competitive Hebbian Learning (CHL) rule, to develop a reverse engineering process. This is a simple and accurate method to reconstruct objects from point clouds obtained from multiple overlapping views using low-cost sensors. In contrast to other methods that may need several stages that include downsampling, noise filtering and many other tasks, the NG automatically obtains the 3D model of the scanned objects. To demonstrate the validity of our proposal we tested our method with several models and performed a study of the neural network parameterization computing the quality of representation and also comparing results with other neural methods like growing neural gas and Kohonen maps or classical methods like Voxel Grid. We also reconstructed models acquired by low cost sensors that can be used in virtual and augmented reality environments for redesign or manipulation purposes. Since the NG algorithm has a strong computational cost we propose its acceleration. We have redesigned and implemented the NG learning algorithm to fit it onto Graphics Processing Units using CUDA. A speed-up of 180× faster is obtained compared to the sequential CPU version.

Dynamical Approach for Real-Time Monitoring of Agricultural Crops

In this paper, a novel approach for exploiting multitemporal remote sensing data focused on real-time monitoring of agricultural crops is presented. The methodology is defined in a dynamical system context using state-space techniques, which enables the possibility of merging past temporal information with an update for each new acquisition. The dynamic system context allows us to exploit classical tools in this domain to perform the estimation of relevant variables. A general methodology is proposed, and a particular instance is defined in this study based on polarimetric radar data to track the phenological stages of a set of crops. A model generation from empirical data through principal component analysis is presented, and an extended Kalman filter is adapted to perform phenological stage estimation. Results employing quad-pol Radarsat-2 data over three different cereals are analyzed. The potential of this methodology to retrieve vegetation variables in real time is shown.

Influence of Incidence Angle on the Coherent Copolar Polarimetric Response of Rice at X-Band

The coherent nature of the acquisition by TerraSAR-X of both copolar channels (HH and VV) enables the generation of many different polarimetric observables with physical interpretation, as have recently been used for monitoring rice fields. In this letter, the influence of incidence angle upon these polarimetric observables is analyzed by comparing three stacks of images that were acquired simultaneously at different incidence angles (22°, 30°, and 40°) during a whole cultivation campaign. We show that the response of observables related to dominance (entropy, ratios of components) and type of scattering mechanisms (alpha angles) is not greatly influenced by incidence angle at some stages: early and advanced vegetative phases, and maturation. Moreover, the acquisition geometry drives the sensitivity to the presence of the initial stems and tillers, being detected earlier at shallower angles. This analysis is a necessary step before studying potential methodologies for combining different orbits and beams for reducing the time between acquisitions for monitoring purposes.

Capacitación turística en comunidades indígenas. Un caso de Investigación Acción Participativa (IAP)

La literatura académica subraya la importancia de involucrar a la comunidad en los procesos de capacitación turística. Sin embargo, apenas hay reflexiones sobre cómo diseñar e implementar la formación en áreas rurales y remotas. En este trabajo se exponen las cuatro fases de un ciclo de Investigación Acción Participativa (IAP), desarrollada en la Selva Lacandona de México con la colaboración de los grupos originarios lacandones y ch’oles. El objetivo de estudio fue la capacitación humana en las áreas de sistemas turísticos, interpretación del patrimonio natural y cultural, y creación de producto. Todo ello complementado con una capacitación específica para mujeres y jóvenes, grupos tradicionalmente relegados en estas comunidades. El relato de las distintas fases de la IAP nos muestra cómo el conocimiento ancestral es la base para una capacitación turística sólida. La involucración de jóvenes estudiantes en los procesos de formación en comunidades, los formatos adaptados a los contextos locales, y los ejercicios de reciprocidad científica, sirven además para la revitalización cultural, el refuerzo de la autoestima y el desarrollo endógeno de los pueblos indígenas.

Latent tuberculosis infection : a diagnostic challenge : Tuberculin skin testing versus interferon-γ release assays

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014

From the initial interest in ‘Why do people often communicate in very "strange" ways on Social Media?’ to a research project on CMC

This presentation is about the inside story of the PhD project El malagueño real, mental y virtual. Configuración de los significados sociales de una variedad urbana in Hispanic Linguistics. That is, the production and perception of the Spanish spoken in the city of Malaga and used on the social network sites Facebook and Tuenti by users from Malaga is analysed. Actually, the southern Spanish variety in question is quite distinct from the national standard in terms of its phonetic features, its prestige, and the attitudes to it. Thus, the project started with the initial interest in «Why do people often communicate in very “strange” ways on social media» which then slightly changed to the final research interest in «What do the different non-standard variants mean in virtual (and real) malagueño?». This long – sometimes hazardous, yet mostly fun – process is exposed in more detail by looking at the research questions, the methods and results. Lastly, the presentation concludes with some lessons learnt and an outlook on possibilities and necessities for further investigation.

Benchmarking analogue models of brittle thrust wedges

We performed a quantitative comparison of brittle thrust wedge experiments to evaluate the variability among analogue models and to appraise the reproducibility and limits of model interpretation. Fifteen analogue modeling laboratories participated in this benchmark initiative. Each laboratory received a shipment of the same type of quartz and corundum sand and all laboratories adhered to a stringent model building protocol and used the same type of foil to cover base and sidewalls of the sandbox. Sieve structure, sifting height, filling rate, and details on off-scraping of excess sand followed prescribed procedures. Our analogue benchmark shows that even for simple plane-strain experiments with prescribed stringent model construction techniques, quantitative model results show variability, most notably for surface slope, thrust spacing and number of forward and backthrusts. One of the sources of the variability in model results is related to slight variations in how sand is deposited in the sandbox. Small changes in sifting height, sifting rate, and scraping will result in slightly heterogeneous material bulk densities, which will affect the mechanical properties of the sand, and will result in lateral and vertical differences in peak and boundary friction angles, as well as cohesion values once the model is constructed. Initial variations in basal friction are inferred to play the most important role in causing model variability. Our comparison shows that the human factor plays a decisive role, and even when one modeler repeats the same experiment, quantitative model results still show variability. Our observations highlight the limits of up-scaling quantitative analogue model results to nature or for making comparisons with numerical models. The frictional behavior of sand is highly sensitive to small variations in material state or experimental set-up, and hence, it will remain difficult to scale quantitative results such as number of thrusts, thrust spacing, and pop-up width from model to nature.

Point clouds of measurements in the Dechen Cave near Iserlohn, Germany

Modeling natural phenomena from 3D information enhances our understanding of the environment. Dense 3D point clouds are increasingly used as highly detailed input datasets. In addition to the capturing techniques of point clouds with LiDAR, low-cost sensors have been released in the last few years providing access to new research fields and facilitating 3D data acquisition for a broader range of applications. This letter presents an analysis of different speleothem features using 3D point clouds acquired with the gaming device Microsoft® Kinect. We compare the Kinect sensor with terrestrial LiDAR reference measurements using the KinFu pipeline for capturing complete 3D objects (< 4m**3). The results demonstrate the suitability of the Kinect to capture flowstone walls and to derive morphometric parameters of cave features. Although the chosen capturing strategy (KinFu) reveals a high correlation (R2=0.92) of stalagmite morphometry along the vertical object axis, a systematic overestimation (22% for radii and 44% for volume) is found. The comparison of flowstone wall datasets predominantly shows low differences (mean of 1 mm with 7 mm standard deviation) of the order of the Kinect depth precision. For both objects the major differences occur at strongly varying and curved surface structures (e.g. with fine concave parts).

Circulars.

Contains notes from the biological, chemical, geological and physical laboratories, etc.

Breath-alcohol testing: disposable breath tester. Part I. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Breath-collection device for delayed breath-alcohol analysis. Part 2. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

International archives of photogrammetry.

Volumes consist of proceedings, reports, and/or reprints of papers of the International Congress of Photogrammetry, or papers from various other congresses and symposia sponsored by the International Society for Photogrammetry.

Technical report[s]

Contract no DA-44-009 Eng. 2435, Department of the Army Project no. 8-35-11-101.

Proceedings of a symposium on preliminary results from the September 1979 Researcher/Pierce IXTOC-I cruise : Key Biscayne, Florida, June 9-10, 1980.

"December 1980."