5,777 research outputs found

    Streaming H.264 scalable video over data distribution service in a wireless environment

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    The Data Distribution Service (DDS) middleware is enjoying a rapid adoption in high-performance, mission-critical networks. At the same time, the H.264 Scalable Video Coding (SVC) has been recently standardized and it is deemed to be an effective solution for video streaming over a channel with time-varying bandwidth, like the wireless one. In these conditions, it is critical to adapt the video bit-rate to the actual wireless capacity, and bit-rate adaptation is extremely simple for a H.264 SVC video. In this paper we devise, evaluate and demonstrate a technique for streaming H.264 SVC video over a DDS middleware. The contribution is threefold: i) we design a structure of the DDS data-unit able to carry H.264 SVC video-units; ii) we devise a receiver-driven rate-control mechanism based on our DDS data-unit and exploiting specific DDS functionality; iii) we implement and show the effectiveness of our mechanism in an 802.11 wireless scenario, comparing our proposal with other solution

    Improved techniques in data analysis and interpretation of potential fields: examples of application in volcanic and seismically active areas

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    Geopotential data may be interpreted by many different techniques, depending on the nature of the mathematical equations correlating specific unknown ground parameters to the measured data set. The investigation based on the study of the gravity and magnetic anomaly fields represents one of the most important geophysical approaches in the earth sciences. It has now evolved aimed both at improving of known methods and testing other new and reliable techniques. This paper outlines a general framework for several applications of recent techniques in the study of the potential methods for the earth sciences. Most of them are here described and significant case histories are shown to illustrate their reliability on active seismic and volcanic areas

    2D Continuous Wavelet Transform of potential fields due to extended source distributions

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    AbstractWe analyse the real Continuous Wavelet Transform 2D (CWT2D) of potential fields for the investigation of potential field singularities. We focus our attention to extended geological sources, in order to verify the reliability of this method with realistic fields. 3D space-scale representation (3D Scalogram) related to synthetic models were generated, showing the Wavelet Transform Modulus Maxima (WTMM) at each scale. The WTMM are related to the shape of the source, so defining some sort of source boundary analysis through the CWT. Wavelets of different order may help to gain resolution and define source features. Selecting a range of scales where the sources behave as if they are approximately isolated, the depth to the source may be estimated basing on the property that the lines joining the modulus maxima of the wavelet coefficients at different scales (WTMML) intersect each other at the edges of the causative body. Therefore, it is possible to manage the information contained in the wavelet transform of fields related to extended sources. In the real case of the anomaly gravity map of the Vesuvius area (Italy), we estimated the depth of the Mesozoic carbonate basement in the Pompei Basin. We showed also how the WTMML information can be integrated to that of another multiscale method, the Depth from Extreme Points (DEXP) transformation, which is also related to the source density distribution of a given region

    Bouguer gravity field of the Tuscan Archipelago (central Italy)

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    In this paper, we present a new Bouguer gravity map of the Northern Tuscan offshore (central Italy), based on original gravity data acquired on the islands of the Tuscan Archipelago. Our dataset integrates 274 unpublished gravity field measurements with 126 available marine gravity data of the northern Tyrrhenian Sea. The Bouguer anomaly map shows a westward and southward increase of the regional gravity field associated with the uplift of the Moho boundary from central Apennines towards the Tyrrhenian Sea. At a local scale, several Bouguer anomalies are well associated with the igneous plutons of the Elba, Montecristo and Capraia islands, as a result of a deep density contrast between the granitoid intrusive rocks and the embedding metamorphic basement. The presented Bouguer anomaly map represents a useful tool for future studies of the complex geological and geodynamical setting of the Tuscan Archipelago and of the buried and deep igneous structures

    Konsep Pengelolaan Perikanan Tangkap Cakalang (Katsuwonus Pelamis) Di Kawasan Teluk Bone Dalam Perspektif Keberlanjutan

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    Fisheries management ideally could prevent the occurrence of overfishing which nowadays has occurred globally, including in Indonesia. On the basis of fishing status and biology of skipjack tuna, as well as analysis of relationship between sea surface temperature and chlorophyll-a with skipjack tuna catches, the fisheries management should implement zoning regulation. The north zone was suggested to be prioritized as a conservation area for protecting skipjack juvenile (< 46,5 cm FL) from fishing activity. The middle and south zones were suggested to be fishing area where sustainable fishing is applied. The Application of these regulations has an implication on total allowable catches from Bone Bay. The number has lower value than the previous MSY and F-opt values. Number of skipjack tuna which was allowed to be caught in the north zone is 573 ton yr -1 , in the middle zone was 5,820 ton yr and in the south zone was 2,210 ton yr -1 . Overall, the value of allowed number of skipjack tuna catches in Bone Bay was estimated to be 8,600 ton yr effort per year is equivalent with 5,376 operational trips from pole and line boats. -1 with fishing-

    A review of the gravity and magnetic studies in the Tyrrhenian Basin and its volcanic districts

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    Since the Sixties, the turning point marked by the Plate Tectonics global theory has provided new ideas for the interpretation of the complex geodynamic evolution of the Mediterranean area. The renewed interest that followed gave a strong impulse to the geological and geophysical investigations of the Mediterranean area and, more specifically, of the Tyrrhenian Basin. Therefore, large scale geophysical surveys and oceanographic cruises were carried out until the end of the Eighties to fill the gap of geophysical information existing in the area until then. Afterwards, short scale surveys were prevalent to improve the detail of the information in areas of geodynamic interest. The gathered data sets allowed new models to be formulated, improving the knowledge of the crustal and lithospheric structure of the Tyrrhenian Basin (and surrounding areas) and the reconstruction of its complex geodynamic evolution. In this frame, the contribution of gravity and magnetic investigations has been unquestionable and deserves a wide-ranging review both on large and small scale. The main features of the potential fields resulting from these surveys will be described and the interpretative models suggested by several authors will be summarized

    The Artemidorus Papyrus: Solving An Ancient Puzzle with Radiocarbon and Ion Beam Analysis Measurements

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    Ancient papyrus manuscripts are one of the most fascinating sources for reconstructing not only ancient life habits but also past literature. Recently, an amazing document has come to the fore due to the heated debates it raised: the so-called Artemidorus papyrus. It is a very long scroll (about 2.5 m) composed of several fragments of different sizes, with inscriptions and drawings on both sides. On the recto of the document, a text about geography and some drawings of heads, feet, and hands are present, while on the verso there are many sketches of animals, both real and fantastic. Its importance in classical studies comes from the fact that some scholars claim that it is the first known transcription of a relatively large fragment by the Greek geographer Artemidorus. However, other scholars think that the papyrus is a fake, drawn in the 19th century AD by a well-known forger. In order to overcome all possible ambiguities, the papyrus has been studied not only on the basis of historical and paleographic criteria but also by scientific techniques. We have contributed to the knowledge about the papyrus by radiocarbon dating the document and by analyzing the composition of the ink using ion beam analysis (IBA). Results are compatible with the scroll being an ancient manuscript: accelerator mass spectrometry (AMS) 14C measurements have dated the papyrus to a period between the 1st century BC and 1st century AD, while IBA measurements have pointed out the use of an organic (carbon-based) ink, which was typical of ancient Roman and Greek times. Details of the measurements are presented to emphasize the importance of combining AMS and IBA results

    Adjustment to COVID-19 Lockdown Among Italian University Students: The Role of Concerns, Change in Peer and Family Relationships and in Learning Skills, Emotional, and Academic Self-Efficacy on Depressive Symptoms

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    In Italy strict containment measures against COVID-19 pandemic were implemented from March to May 2020 with home confinement and schools and universities closed. Students shifted to remote learning, experienced a forced isolation from peers and an increased sharing of time and spaces with the family. The influence of these aspects on the psychological adjustment of university students is largely unexplored. This paper was aimed at investigating the role of some correlates of depressive symptoms specific to the lockdown condition experienced by young university students, namely contagion concern, perceived worsening of family, and peer relationships and perceived worsening of learning skills. Moreover, the possible mediating effects of emotional and academic self-efficacy in these relationships were examined. Data were collected from 296 Italian university students (aged 18–25 years; 83% female students) through an online survey by means of a snowball sampling methodology in May 2020. Significant depressive symptoms were reported by 67% of participants. Contagion concerns were related to depressive symptoms through the mediating effect of emotional self-efficacy. Worsening of learning skills was related to depressive symptoms through the mediating effect of academic self-efficacy. Depressive symptoms were directly related to worsening of family relationships but unrelated to worsening of peer relationships. Results are discussed in relation to the need of preventive interventions for this specific population in view of academic activities planning in the post-COVID 19 period
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