A reduced-complexity and asymptotically efficient time-delay estimator

This paper considers the problem of estimating the time delays of multiple replicas of a known signal received by an array of antennas. Under the assumptions that the noise and co-channel interference (CCI) are spatially colored Gaussian processes and that the spatial signatures are arbitrary, the maximum likelihood (ML) solution to the general time delay estimation problem is derived. The resulting criterion for the delays yields consistent and asymptotically efficient estimates. However, the criterion is highly non-linear, and not conducive to simple minimization procedures. We propose a new cost function that is shown to provide asymptotically efficient delay estimates. We also outline a heuristic way of deriving this cost function. The form of this new estimator lends itself to minimization by the computationally attractive iterative quadratic maximum likelihood (IQML) algorithm. The existence of simple yet accurate initialization schemes based on ESPRIT and identity weightings makes the approach viable for practical implementation.Peer ReviewedPostprint (published version

Las autoridades del 'Diccionario enciclopédico hispano-americano de literatura, ciencias y artes' (1887-1898) de la Editorial Montaner y Simón

En el siglo XIX se produce la aparición del diccionario enciclopédico. Aunque es posible encontrar ciertos rasgos de este nuevo género lexicográfico en otras obras, su fundador fue el 'Diccionario nacional' (1846) de Ramón Joaquín Domínguez. Con posterioridad se publicaron otros repertorios que siguen los pasos de Domínguez, como el 'Diccionario enciclopédico de la lengua española' (1853-1855) de los editores Gaspar y Roig. Este género gozó de gran aceptación entre el público; así lo ponen de manifiesto las diecisiete ediciones del diccionario de Domínguez y las quince del editado por Gaspar y Roig. A fines de siglo ven la luz otros dos diccionarios enciclopédicos, uno de ellos dirigido por Zerolo, Toro e Isaza, de 1895, y otro publicado por la casa Montaner y Simón. Esta última obra, denominada 'Diccionario enciclopédico hispano-americano de literatura, ciencias y artes', se publicó entre 1887 y 1898. Su aparición no solo supuso (según Manuel Seco) el golpe de muerte de los diccionarios de Domínguez y de Gaspar y Roig y el inicio de una nueva etapa para este tipo de obra lexicográfica, sino que retomó un principio metodológico abandonado hacía mucho tiempo: la práctica de la cita textual. Pues bien, el propósito que persigue este estudio es mostrar el lugar que ocupa el 'Diccionario enciclopédico hispano-americano' en la Historia de la Lexicografía Española, centrándonos, en esta ocasión, en una de sus características, a nuestro juicio, más importante, la aportación de autoridades en determinados artículos como garantes de sus acepciones. The nineteenth century witnesses the birth of a new type of lexicographical work: the encyclopaedic dictionary. Although it is possible to find some characteristics of this new genre in other works, the starting point was the 'Diccionario nacional' (1846-1847) by Ramón Joaquín Domínguez, whose pattern was later followed by other works, such as the 'Diccionario enciclopédico de la lengua española' (1853-1855) by Gaspar and Roig. The publication of seventeen editions of Domínguez’s dictionary and fifteen of Gaspar and Roig’s proves the success of this kind of work. By the end of the nineteenth century, other two encyclopaedic dictionaries were published: one by Zerolo, Toro and Isaza (1895); and the other one,'Diccionario enciclopédico hispano-americano de literatura, ciencias y artes' (1887- 1898), by the publishing house Montaner and Simón. According to Manuel Seco, the publication of the latter meant not only the death blow of Domínguez’s and Gaspar and Roig’s dictionaries and the beginning of a new stage for this kind of lexicographical work, but also the return to a methodological principle neglected long ago, that is, the use of textual quotations. This article, thus, attempts to show the significance of the 'Diccionario enciclopédico hispano-americano de literatura, ciencias y artes' in the History of Spanish Lexicography, highlighting what is, in our opinion, its most important contribution: the use of authorities as guarantors of the meanings of some entries

Detection of enteric parasite DNA in household and bed dust samples: potential for infection transmission.

BACKGROUND: Enteric parasites are transmitted in households but few studies have sampled inside households for parasites and none have used sensitive molecular methods. METHODS: We collected bed and living room dust samples from households of children participating in a clinical trial of anthelmintic treatment in rural coastal Ecuador. Dust was examined for presence of DNA specific for 11 enteric parasites (Ascaris lumbricoides, Trichuris trichiura, Ancylostoma duodenale, Necator americanus, Strongyloides stercoralis, Toxocara canis and T. cati, Giardia lamblia, Blastocystis hominis, Cryptosporidium spp., and Entamoeba histolytica) by quantitative PCR (qPCR). RESULTS: Of the 38 households sampled, 37 had positive dust for at least one parasite and up to 8 parasites were detected in single samples. Positivity was greatest for B. hominis (79% of household samples) indicating a high level of environmental fecal contamination. Dust positivity rates for individual pathogens were: S. stercoralis (52%), A. lumbricoides (39%), G. lamblia (39%), Toxocara spp. (42%), hookworm (18%) and T. trichiura (8%). DNA for Cryptosporidium spp. and E. histolytica was not detected. Bed dust was more frequently positive than floor samples for all parasites detected. Positivity for A. lumbricoides DNA in bed (adjusted OR: 10.0, 95% CI: 2.0-50.1) but not floor dust (adjusted OR: 3.6, 95% CI: 0.3-37.9) was significantly associated with active infections in children. CONCLUSIONS: To our knowledge, this is the first use of qPCR on environmental samples to detect a wide range of enteric pathogen DNA. Our results indicate widespread contamination of households with parasite DNA and raise the possibility that beds, under conditions of overcrowding in a humid tropical setting, may be a source of transmission

Detecting photon-photon scattering in vacuum at exawatt lasers

In a recent paper, we have shown that the QED nonlinear corrections imply a phase correction to the linear evolution of crossing electromagnetic waves in vacuum. Here, we provide a more complete analysis, including a full numerical solution of the QED nonlinear wave equations for short-distance propagation in a symmetric configuration. The excellent agreement of such a solution with the result that we obtain using our perturbatively-motivated Variational Approach is then used to justify an analytical approximation that can be applied in a more general case. This allows us to find the most promising configuration for the search of photon-photon scattering in optics experiments. In particular, we show that our previous requirement of phase coherence between the two crossing beams can be released. We then propose a very simple experiment that can be performed at future exawatt laser facilities, such as ELI, by bombarding a low power laser beam with the exawatt bump.Comment: 8 pages, 6 figure

5G mmwave positioning for vehicular networks

5G technologies present a new paradigm to provide connectivity to vehicles, in support of high data-rate services, complementing existing inter-vehicle communication standards based on IEEE 802.11p. As we argue, the specific signal characteristics of 5G communication turn out to be highly conducive for vehicle positioning. Hence, 5G can work in synergy with existing on-vehicle positioning and mapping systems to provide redundancy for certain applications, in particular automated driving. This article provides an overview of the evolution of cellular positioning and discusses the key properties of 5G as they relate to vehicular positioning. Open research challenges are presented

NLM at ImageCLEF 2017 caption task

This paper describes the participation of the U.S. National Library of Medicine (NLM) in the ImageCLEF 2017 caption task. We proposed different machine learning methods using training subsets that we selected from the provided data as well as retrieval methods using external data. For the concept detection subtask, we used Convolutional Neural Networks (CNNs) and Binary Relevance using decision trees for multi-label classification. We also proposed a retrieval-based approach using Open-i image search engine and MetaMapLite to recognize relevant terms and associated Concept Unique Identifiers (CUIs). For the caption prediction subtask, we used the recognized CUIs and the UMLS to generate the captions. We also applied Open-i to retrieve similar images and their captions. We submitted ten runs for the concept detection subtask and six runs for the caption prediction subtask. CNNs provided good results with regards to the size of the selected subsets and the limited number of CUIs used for training. Using the CUIs recognized by the CNNs, our UMLS-based method for caption prediction obtained good results with 0.2247 mean BLUE score. In both subtasks, the best results were achieved using retrieval-based approaches outperforming all submitted runs by all the participants with 0.1718 mean F1 score in the concept detection subtask and 0.5634 mean BLUE score in the caption prediction subtask

Integration of airborne and ground observations of nitryl chloride in the Seoul metropolitan area and the implications on regional oxidation capacity during KORUS-AQ 2016

Nitryl chloride (ClNO2) is a radical reservoir species that releases chlorine radicals upon photolysis. An integrated analysis of the impact of ClNO2 on regional photochemistry in the Seoul metropolitan area (SMA) during the Korea-United States Air Quality Study (KORUS-AQ) 2016 field campaign is presented. Comprehensive multiplatform observations were conducted aboard the NASA DC-8 and at two ground sites (Olympic Park, OP; Taehwa Research Forest, TRF), representing an urbanized area and a forested suburban region, respectively. Positive correlations between daytime Cl2 and ClNO2 were observed at both sites, the slope of which was dependent on O3 levels. The possible mechanisms are explored through box model simulations constrained with observations. The overall diurnal variations in ClNO2 at both sites appeared similar but the nighttime variations were systematically different. For about half of the observation days at the OP site the level of ClNO2 increased at sunset but rapidly decreased at around midnight. On the other hand, high levels were observed throughout the night at the TRF site. Significant levels of ClNO2 were observed at both sites for 4-5 h after sunrise. Airborne observations, box model calculations, and back-trajectory analysis consistently show that these high levels of ClNO2 in the morning are likely from vertical or horizontal transport of air masses from the west. Box model results show that chlorine-radical-initiated chemistry can impact the regional photochemistry by elevating net chemical production rates of ozone by 25% in the morning

A robotized dumper for debris removal in tunnels under construction

Tunnels in construction exhibit many challenges for automation. In this work we address the robotization of a conventional dumper for debris removal during the construction of tunnels, in the framework of a technological transfer project. The goal is to convert a dumper into an autonomous vehicle capable of planning, navigate and localize itself. Planning and navigation techniques have been adapted to the special kinodynamic characteristics of the vehicle. The difficulties for having a precise continuous localization in this kind of scenarios, due to the irregularities of the terrain, the changing illumination and the own scenario, have driven to develop hybrid localization techniques to integrate continuous and discrete information, coming from the navigation sensors, some semantic geometric features, and the signal strength propagation in tunnel scenarios. Simulation and real-world experiments are described, and some preliminary results are discussed