12,842 research outputs found
Wide binary stars in the Galactic field : a statistical approach
No full textThis thesis focuses on the statistical properties of wide binary (WB) star systems in the Galactic field. With projected separations larger than 200 AU and, consequently, having very low binding energies, WB are sensitive probes of the Galactic gravitational potential making them an interesting tool to constrain the dark matter (DM) content in the Milky Way Galaxy. For the present study we select a homogeneous sample covering about 675 square degrees in the direction of the Northern Galactic Pole. It contains nearly 670000 main sequence stars with apparent magnitudes between 15 and 20.5 mag and spectral classes later than G5. The data were taken from the Sloan Digital Sky Survey. We construct the two-point correlation function (2PCF) for angular separations between 2 and 30 arcseconds. The resulting clustering signal is modelled by means of the Wasserman-Weinberg technique. We show that the distribution of semi-major axis is consistent with the canonical …pik law and infer that about 10% of all stars in the solar neighbourhood belong to a WB system. The 2PCF method is, however, seriously limited by the noise from optical pairs, especially for the widest systems, which would provide the most stringent constraints of the DM's nature. To reduce the noise from optical pairs and to increase the sensitivity of the analysis at larger separations, we include distance information from photometric parallaxes. Introducing a novel weighting procedure based on the binding probability of a double star, we infer the distribution of colours and mass ratios, which were carefully corrected for observational selection effects. About 4000 WBs were taken into account statistically, whose components have masses between 0.2 and 0.85 solar masses. We find that the WB colour distribution is in accord with the colour distribution of single field stars. However, pairs with a mass difference exceeding 0.5 solar masses seem to be systematically underrepresented as compared to a random pairing of field stars. Our results are broadly in agreement with prior studies but a direct comparison is often difficult or even impossible. We compiled a 'ranked list' of WB candidates that will prove to be useful for follow-up studies. Due to lack of information about the relative velocities of the pairs, the limitation concerning the widest pairs could not be entirely overcome. A further drawback of our approach is clearly the need for a sophisticated modelling to allow for selection effects. The method, however, successfully circumvents the limitations of studies based on proper motions. The novel procedure presented in this thesis can therefore be regarded as complementary to common proper motion studies, and constitutes a viable approach to study the statistical properties of WBs in the Galactic field
Wenn es regnet: Den Regentropfen auf der Spur
No full textDas Dossier unterstützt bei der Planung und Umsetzung von thematischen Unterrichtssequenzen für den Kindergarten und die Basisstufe, die unkompliziert auch für die 1./2. Klasse adaptiert werden können. Die praxiserprobten Spiel- und Lernumgebungen bieten entwicklungsorientierte Zugänge zu den Kompetenzen aus dem Fachbereich NMG (Lehrplan 21) und zeigen Verbindungen zu anderen Fachbereichen auf. Bausteine: So ein Regenwetter! - Regen bewusst wahrnehmen und erkennen; Jede Menge Regentropfen - Messen, wie viel es regnet; Grosse Pfützen, kleine Pfützen - Untersuchen wohin das Regenwasser verschwindet; Woher kommt der Regen? - Verstehen wie Regen entsteht; Alles wasserdicht? - Herausfinden, was vor Regen schützt; Kostbares Nass - Regenwasser sammeln und nutzen
MABS validation through repeated execution and data mining analysis
No full textAgent Based Modelling is the most interesting and advanced approach for simulating a complex system: in a social context, the single parts and the whole are often very hard to describe in detail. Besides, there are agent based formalisms which allow to study the emergency of social behaviour with the creation and study of models, known as artificial societies. Thanks to the ever increasing computational power, it's been possible to use such models to create software, based on intelligent agents, which aggregate behaviour is complex and difficult to predict, and can be used in open and distributed systems. Data mining is born in the last decades in order to help users in finding useful knowledge from the otherwise overwhelming amount of data available nowadays from the web and the data collected every day by companies. Data Mining techniques can therefore be the keystone to reveal non-trivial knowledge expressed by the initial assumption used to build the micro-level of the model and the structure of the society of agents that emerged from the simulation
The changing morphology of the Volturno delta (northern Campania, Italy): geological architecture and human influence
No full textThe present geomorphology of the Volturno River delta system (northern Campania, southern Italy) is largely a product of complex, long-lived relationships between geological evolution and human impacts.
In order to assess the main drivers of the changed landscape in the last centuries, a multidisciplinary study was carried out by combining geological and historical data. The study was based on geological and geophysical data, including about 1800 stratigraphic well logs to reconstruct the stratigraphic architecture of the delta plain and ca. 180 km of very high resolution single channel reflection profiles to image the stratigraphic pattern of the continental shelf and the offshore delta (Buffardi et al., 2021). Cartographic sources from the last 150 years were acquired, georeferenced and managed into a GIS environment, to support geomorphological interpretation. Bathymetric data acquired in 1887 and in 1987 were compared to extract seafloor changes in the delta offshore. Land use changes were also assessed since the 1957 up to present (Donadio et al., 2017; Ruberti et al., 2017; Ruberti and Vigliotti, 2017).
The Volturno delta is characterized by a micro-tidal regime and moderate-to-high wave energy. The Holocene reconstruction of the Volturno coastal plain evolution evidenced the control of climatic changes (and consequently sediment supply and global eustatic variations) on the depositional history. Similarly to other Italian delta plains, 6.5 ky cal BP a coastal progradational phase established, allowing the formation of a wave-dominated delta system, with flanking strandplains forming beach-dune ridges partially enclosing lagoonal-marshy areas. Beach and lagoonal environments persisted along the present coastal zone up to the Roman age.
The present landscape appears largely inherited by the past MIS5 and LGM landscapes. A progressive increment of anthropic forcing took place after 2000 yr BP but the strongest modifications of the landscape occurred since the end of the XVII century, when, during the Spanish vice-kingdom, it was subjected to major land reclamation aimed at elevating the land surface by filling the low lands with earth material settled by rivers' water that were diverted, canalized and branched into diversion canals reaching the inner parts of the sedimentation tanks. Progradation of the delta ended during the early-middle XIX century. A peak of major alterations of the deltaic environment, and retreat of the coastline was attained between the 1960s and the 1990s. It is evident that the transformations of the landscape that have taken place over the last millennium are largely caused by anthropogenic impacts (i.e. reclamation, development of drainage network, land use changes). The sediment input of the river to the Tyrrhenian Sea sharply decreased, thus resulting in a dramatic change of the deltaic morphology and significant coastal land loss. The coastal zone, considered as a dissipative-type shoreline, evolved to an irreversible non-dissipative inshore profile characterized by mean erosional rates of 5m/yr along the beaches and 24 m/yr on the delta mouth. The river delta changed from a cuspate, wave-dominate delta to arcuate and eventually delta-estuary type
Facades of the Libreria di San Marco in Venice, The: An Interpretation of the Design Process
No full text"A new work in which I propose an interpretation of the design process Sansovino used to create the magnificent facades of the Libreria di San Marco in Venice, a masterpiece of Renaissance architecture." Sent to Marquand librarian by author Dec. 202
Art without an Author: Vasari’s Lives and Michelangelo’s Death
No full textMonografia sulla rappresentazione di Michelangelo nelle due edizioni delle Vite, sulla storia del libro e la questione della sua paternitàBook dedicated to the representation of Michelangelo in Vasari's Lives of the Artists, to the history of the book, and to the problem of its authorshi
Depositional architectures and facies distribution in turbiditic sandstone channel-fills. A case-study from the Gorgoglione Flysch Formation (Basilicata, Southern Italy)
No full textTurbidite channels are among the most important deep-water hydrocarbon reservoirs currently being explored. Recent advances in the understanding of these depositional systems result from significant improvements in modern 3-D seismic imaging, showing their three-dimensional stratal complexity and architectures at multiple scales. However, lateral and vertical variability of reservoir properties are associated with differences in the nature of channel fill and their stacking patterns, which commonly are at scales below the resolution of even high resolution 3-D seismic datasets. For this reason, outcrop studies are powerful tools to investigate the properties of channel-fill deposits and improve the characterization of channel systems.
A field-based study is presented from a key stratigraphic interval of the Gorgoglione Flysch Fm, a Miocene turbiditic succession exposed within a piggy-back basin in the Southern Apenninic Chain of Italy. This formation includes 10-to-60-m-thick amalgamated sandbodies, systematically offset-stacked to form channel complexes that are laterally associated with heterolithic overbank deposits. There is an upward evolution from these laterally-migrating amalgamated channelized sedimentary bodies into isolated sand-filled channels, 4-to-35 m thick, displaying considerable lateral thickness variability. Systematic bed-scale stratigraphic measurements on the sandbodies reveal a recurring motif of three main coarse-grained facies forming a distinctive channel-fill facies association. The basal LC1 lithofacies consists of pebble- to cobble-sized conglomerate within a poorly-sorted, very coarse-grained sandstone matrix, interpreted as a channel-base lag resulting from the bypassing of high-density turbidity currents, characterizing the earlier phases of the channel formation. LC1 lithofacies is commonly overlain by LC2 lithofacies, composed of normally-graded, coarse-to medium-grained sandstones, predominantly structureless or plane-parallel laminated. This lithofacies has been interpreted as the sedimentary product of collapsing, sand-rich high-density turbidity currents during the backfilling stage. LC3 lithofacies is dominant towards the top of the sandbodies; it is characterized by multiple sets of 3D dune-scale cross stratification in medium- to coarse-grained sandstones, whose deposition is related to the influence of persistent energetic traction currents at the end of turbiditic events that reworked the topmost part of the channel-fills. Geometry, continuity, and distribution of sandstone facies at the scale of channel-fills, combined with palaeoflow analysis, provide insights for the identification of the different parts of the channels (axis / off-axis / margin) and locally the characterization of the degree of sinuosity. The detailed description and interpretation of these deposits can help to better understand the processes involved in the evolution of turbiditic channels for an accurate characterization of deep-water reservoirs
Unterrichtsvideos in der Schweizer Lehrpersonenbildung
No full textDie Arbeit mit videografierten Unterrichtssequenzen ist zu einem bedeutsamen Instrument in der Aus- und Weiterbildung von Lehrpersonen geworden. Doch was heisst es, Videos für die Hochschullehre zu erstellen, Unterricht mit unterschiedlichen videografischen Technologien zu erfassen? Welche Chancen und Herausforderungen bietet der Einsatz von Videos für den Aufbau beruflicher Kompetenzen?
Der vorliegende Sammelband vereinigt Beiträge, die diese Fragen im Kontext der schweizerischen Aus- und Weiterbildung von Lehrpersonen aller Schulstufen untersuchen
Videobasierte Fallarbeit zur formativen Beurteilung im Bildnerischen Gestalten
No full textDieser Beitrag untersucht die Förderung professioneller Kompetenz zur formativen Beurteilung im Bildnerischen Gestalten von Studierenden der Pädagogischen Hochschule Bern. Dafür wurde eine Gruppe, die sich mit videobasierter Fallarbeit befasste, mit einer zweiten Gruppe ohne Fallarbeit verglichen. Die Ergebnisse zeigen, dass die videobasierte Fallarbeit als hilfreiche Methode für den Transfer von Theorie in die Unterrichtspraxis empfunden wurde. Studierende, die mit dieser fallbasierten Methode arbeiteten, setzten formative Beurteilungen im Fachpraktikum spezifischer und strukturierter um und nutzten kompetenzorientierte Rückmeldungen effektiver. Dies spricht für praxisnahe Lehr-Lern-Settings in der Lehrpersonenausbildung
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