1,720,973 research outputs found
Spatio-temporal analysis of intense convective storms tracks in a densely urbanized Italian Basin
Full text linkIntense convective storms usually produce large rainfall volumes in short time periods, increasing the risk of floods and causing damages to population, buildings, and infrastructures. In this paper, we propose a framework to couple visual and statistical analyses of convective thunderstorms at the basin scale, considering both the spatial and temporal dimensions of the process. The dataset analyzed in this paper contains intense convective events that occurred in seven years (2012-2018) in the Seveso-Olona-Lambro basin (North of Italy). The data has been acquired by MeteoSwiss using the Thunderstorm Radar Tracking (TRT) algorithm. The results show that the most favorable conditions for the formation of convective events occur in the early afternoon and during summertime, confirming the key role of the temperature in atmospheric convection. The orography emerged as a driver for convection, which takes place more frequently in mountain areas. The storm paths analysis shows that the predominant direction is from South-West to North-East. Considering storm duration, long-lasting events reach higher values of radar reflectivity and cover more extended areas than short-lasting ones. The results obtained can be exploited for many practical applications including nowcasting, alert systems, and sensors deployment
Precipitable Water Vapor Content from GNSS/GPS: Validation Against Radiometric Retrievals, Atmospheric Sounding and ECMWF Model Outputs over a Test Area in Milan
No full textThe availability of atmospheric water vapor content observations, with high temporal and spatial resolution, proved to have a high impact in the prediction of heavy rain events obtained from numerical weather prediction models. Several techniques can be applied to derive such observations. Some of them are well consolidated, some others are still under development. The focus of this work is to provide a statistical assessment of the consistency between four different techniques for water vapor monitoring, and specifically for precipitable water vapor (PWV) retrieval: radiometer-derived, European Centre for Medium-Range Weather Forecasts (ECMWF) meteorological model derived, GNSS-derived and atmospheric sounding derived PWV. An overview of the data processing needed to estimate such parameter in the four cases is given to highlight how the corresponding PWV is related to the actual atmospheric water vapor content. Time series of PWV obtained with the different methods are compared for a case study in Milan, over a period of one year (March 1st, 2018–February 11th, 2019). A four-channel Ka-band/W-band radiometer located in the main campus of Politecnico di Milano is employed in association with a GNSS dual-frequency receiver (MILA), part of a regional network and installed in the same campus, 280 m far from the radiometer. GNSS data are processed by the goGPS software, applying a precise point positioning strategy. A comparison with atmospheric sounding (Milano-Linate station, located at about 6 km from the GNSS receiver), as well as with PWV derived from the ECWMF model (operational products), is also given. Results show a good agreement between the outputs of the four different data sources confirming GNSS as a valid alternative to the well consolidated techniques and opening the way to its synergistic use with co-located radiometers
Increased secretion of the amino-terminal fragment of amyloid precursor protein in rat brain of animals characterized by a constitutive upregulation of protein kinase C. J. Neurochem. 68, 2523-2529, 1997
No full textUnderstanding Severe Weather Events at Airport Spatial Scale
No full textSevere weather events locally developing in a short time range are one of the major risks for aviation safety. Nowcasting and understanding the initiation of storm cells is still a challenging topic for meteorology and atmospheric physics. We combined the use of weather radar, weather stations and ground-based GNSS receivers to characterize the severe convection development at airport spatial scale over Milan. In this work, we show the analysis of a case study and a statistical analysis based on 40 randomly selected severe weather events. The results highlight a typical trend of the GNSS signal and low-level wind convergence, revealing the cell development. This is the starting point to develop a nowcasting algorithm based on neural network initialized with a dense network of GNSS receivers and lightning detectors that we are building in the area
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Structural health monitoring of bridges based on GNSS
No full textThis paper presents an overview of Global Navigation Satellite System (GNSS) technology for Structural Health Monitoring (SHM) of bridges. Peculiarities and requirements related to GNSS technology, installation features, data management, signal processing and significance of the results to ultimately support life-cycle frameworks for optimal management of critical bridge assets are discussed. A case study of GNSS-based SHM of an existing bridge is also presented. The investigated bridge is part of a group of pilot bridges equipped with different SHM systems within a project for risk-based bridge management and monitoring at regional scale. Results of the GNSS-based SHM of the bridge, with emphasis on data processing and correlation analysis, are presented for a monitoring time interval of about two years
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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