1,721,041 research outputs found
Geo-archaeological study of the territory of Burnum’s Roman site (Croatia) through LANDSAT multi-temporal satellite images and high resolution GeoEye
Full text linkThe object area of the study was analysed with a geographical and geo-archaeological approach, integrating the data by using geomatic techniques (Satellite Remote Sensing and Geographical Information System). The processing of the data of the high resolution Satellite images allowed us to discover that in the karst environment, like the one in which Burnum was established, the areas with a higher humidity and vegetation concentration are the results of the anthropic action due to frequentation in the Roman Age. The infrastructure and buildings, the earth moving conducted to raise the original natural surface levels, and the subsequent collapse of buildings during the stage when the site was abandoned, determined the formation of a significant substrate in the area. Thanks to the results of the surveys and data, the positive responses of the image analysis through the Band Ratio and the enhancement procedures highlighted the differences in the soil’s patterns/weaving. This method of investigation, the results of which will be verified by carrying out targeted surveys, suggests the presence of residential infrastructure (canabae) in the area surrounding the Roman site and especially along the main roads. Therefore, the archaeological site of Burnum, today corresponding to approximately 8 ha, could be doubled, adding even further to the importance of the role that the city had in this part of the Roman province of Dalmatia
Active tectonics in northern Victoria Land (Antarctica) inferred from the integration of GPS data and geologic setting
No full textA semipermanent Global Positioning System (GPS) network of 30 vertices known as
the Victoria Land Network for Deformation Control (VLNDEF) was set up in the Austral
summer of 1998 in northern Victoria Land (NVL), including Terra Nova Bay (TNB),
Antarctica. The locations were selected according to the known Cenozoic fault framework,
which is characterized by a system of NW‐SE regional faults with right‐lateral, strike‐slip
kinematics. The TNB1 permanent GPS station is within the VLNDEF, and following
its installation on a bedrock monument in October 1998, it has been recording almost
continuously. The GPS network has been surveyed routinely every two summers, using
high‐quality, dual‐frequency GPS receivers. In this study we present the results of a
distributed session approach applied to the processing of the GPS data of the VLNDEF.
An improved reference frame definition was implemented, including a new Euler pole,
to compute the Antarctic intraplate residual velocities. The projection of the residual
velocities on the main faults in NVL show present‐day activities for some faults, including
the Tucker, Leap Year, Lanterman, Aviator, and David faults, with right‐lateral strike‐slip
kinematics and local extensional and compressional components. This active fault
pattern divides NVL into eight rigid blocks, each characterized by its relative movements
and rigid rotations. These show velocities of up to several millimeters per year, which
are comparable to those predicted by plate tectonic theory at active plate margins
Sea Tide Analysis Derived by PPP Kinematic GPS Data Acquired at David-Drygalski Floating Ice Tongue (Antarctica)
Full text linkOne of the most important ice-stream of the Victoria Land (VL) is the David Glacier, which produces 100 km long floating sea-ward ice tongues in the Ross Sea, the Drygalski Ice Tongue (DIT). The ice-tongue slides down into the sea increasing its velocity rates and together with ice-stream movement sometime produce characteristic ice-quakes. This paper shows the effects of the sea tidal variation on both horizontal and vertical components of movement at a portion of DIT. Ocean tide is usually modelled by a series of harmonic coefficients (amplitude and phase), which are estimated through several systems of measurement. For the study area, these data are made available by the Antarctic Tide Gauge (ATG) database. Moreover, tidal data recorded by a multiparameter underwater tide gauge, which was installed at Mario Zucchelli Station (MZS), the Italian Antarctic Base, in February 2006, are being processed again. The kinematic Precise Point Positioning (PPP) processing was adopted for the analysis of 24 days of acquisition performed with a GPS receiver located in the initial part of DIT, about 46 km seaward from the Ice Fault David Cauldron. The analysis of harmonic tidal components has shown that PPP solutions show correct values of diurnal and semi-diurnal tidal components and therefore can provide valuable information in the coastal area covered by ice tongues
Sea Tide Influence on Ice Flow of David Drygalski’s Ice Tongue Inferred from Geodetic GNSS Observations and SAR Offset Tracking Analysis
Full text linkDavid Glacier and Drygalski Ice Tongue are massive glaciers in Victoria Land, Antarctica. The ice from the East Antarctic Ice Sheet is drained through the former, and then discharged into the western Ross Sea through the latter. David Drygalski is the largest outlet glacier in Northern Victoria Land, floating kilometers out to sea. The floating and grounded part of the David Glacier are the main focus of this article. During the XXI Italian Antarctic Expedition (2005-2006), within the framework of the National Antarctic Research Programme (PNRA), two GNSS stations were installed at different points: the first close to the grounding line of David Glacier, and the second approximately 40 km downstream of the first one. Simultaneous data logging was performed by both GNSS stations for 24 days. In the latest data processing, the kinematic PPP technique was adopted to evaluate the dominant diurnal components and the very small semi-diurnal variations in ice motion induced by the ocean tide and the mean ice flow rates of both GNSS stations. Comparison of the GNSS time series with predicted ocean tide calculated from harmonic coefficients of the nearest tide gauge stations, installed at Cape Roberts and Mario Zucchelli Station, highlight different local response of the glacier to ocean tide, with a minor amplitude of vertical motion at a point partially anchored at the bedrock close to the grounding line. During low tide, the velocity of the ice flow reaches its daily maximum, in accordance with the direction of seawater outflow from the fjord into the ocean, while the greatest daily tidal excursion generates an increase in the horizontal ice flow velocity. With the aim to extend the analysis in spatial terms, five COSMO-SkyMED Stripmap scenes were processed. The comparison of the co-registered offset tracking rates, obtained from SAR images, with the GNSS estimation shows good agreement
Turning on Organic Radical Emitters
No full textRadical emitters have attracted considerable interest because of their potential to surpass the limitations of singlet emitters due to spin statistics, thereby revolutionizing organic LEDs. Utilizing the well-known Pariser-Parr-Pople (PPP) model for correlated electrons in pi-conjugated systems, we perform extended configuration interaction with single, double, and triple excitations (XCISDT) to explore the photophysics of various phenalenyl radicals differently decorated with nitrogen atoms. By introducing the PPP particle-hole difference operator and connecting it to DFT calculations, we offer a new tool for predicting highly emissive organic radicals using ground-state quantum chemistry methods
Attività solare, effetti ionosferici e servizi NRTK: quali connessioni?
No full textL’attività solare si trova in un periodo di rapida crescita all’interno
di un ciclo periodico della durata di 11 anni. Il campo magnetico
terrestre ne è influenzato e con esso l’equilibrio dello strato superiore
dell’atmosfera terrestre, la ionosfera, dove la propagazione dei segnali
GNSS subisce i ben noti fenomeni di rifrazione. Considerato l’ulteriore
incremento di attività solare fino ai massimi previsti per 2013, ci saranno ripercussioni sulle prestazioni dei servizi NRTK
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
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