1,721,027 research outputs found
Field observations of sand-mixing depths on steep beaches
No full textA series of field studies were carried out on three Portuguese beaches (Garrao, Faro and Culatara) to assess sand-mixing depths under a range of wave heights (0.34-0.80 m), wave periods (5.1-7.0 s) and mean grain sizes (0.26 and 0.38 mm). All the studied beaches had a reflective profile with a steep upper foreshore (tanβ of 0.10-0.14) and a more gentle low-tide terrace. In all experiments, plunging waves were breaking on the beach face. The study has identified a linear correlation between significant wave height at breaking (H(b)), and average sand-mixing depth (Z(m)), whereby Z(m) = 0.27 H(m). The empirical relationship is ten times larger than a previous one proposed by other authors working on gentle-slope dissipative beaches, and confirms previous findings on similar reflective beaches carried out in the USA. It was also confirmed that Z(m) is related to wave period, but does not seem to be a function of mean sand size
Studi di morfodinamica sedimentaria su spiagge: strumentazioni, processi fisici e stato delle conoscenze attuali
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Longshore Sand Transport: a Comparison between Field Observations and Predictions of Numerical Models and Implication for Coastal Erosion Studies
No full textStudy on longshore sand transpor
Fluorescent sands for measurements of longshore transport rates: a case study from Praia de Faro in southern Portugal
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Anthropogenic impacts on Iberoamerican coastal areas: Historical processes, present challenges, and consequences for coastal zone management
Full text linkThe coastal zone in Portugal, Spain, Brazil and Argentina is declared as a common resource. However, since the touristic boom started in the 1960s, these countries have not considered adequately the available management instruments due to the rapid demand for seaside spaces, the interest to improve rapidly the national economy, and the limitations of the scientific knowledge about the impacts on the natural systems. The environmental consequences of anthropogenically-triggered processes in Latin America occurred somewhat later than in southern Europe, but similar errors were repeated. The investors demanded rapid benefits, without care for social development or environmental protection, and disregarding scientific knowledge. As in other coastal areas of the world, there are strong concerns about the consequences of climate change and sea-level variations on these coasts, especially in areas of extensive urban development.Fil: Alveirinho Dias, Joao. Universidade do Algarve; PortugalFil: Cearreta, Alejandro. Universidad del País Vasco; EspañaFil: Isla, Federico Ignacio. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Geología de Costas y del Cuaternario. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto de Geología de Costas y del Cuaternario; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Michaelovitch de Mahiques, Michel. Universidade de Sao Paulo; Brasi
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
Seismic stacking pattern of the Faro-Albufeira contourite system (Gulf of Cadiz): a Quaternary record of paleoceanographic and tectonic influences
No full text.A Quaternary stratigraphic stacking pattern on the Faro-Albufeira drift system has been determined by analysing a dense network of high-resolution single-channel seismic reflection profiles. In the northern sector of the system an upslope migrating depositional sequence (elongate separated mounded drift) parallel to the margin has been observed associated with a flanking boundary channel (Alvarez Cabral moat) that depicts the zone of Mediterranean Outflow Water (MOW) acceleration and/or focussing. A consequent erosion along the right hand border and deposition on the left hand flank is produced in this sector. The sheeted aggrading drift is the basinward prolongation of the elongate separated mounded drift, and developed where the MOW is more widely spread out. The overall sheeted contourite system is separated into two sectors due to the Diego Cao deep. This is a recent erosional deep that has steep erosional walls cut into Quaternary sediments. Two major high-order depositional sequences have been recognised in the Quaternary sedimentary record, Q-I and Q-II, composed of eight minor high-order depositional sequences (from A to H). The same trend in every major and minor depositional sequence is observed, especially in the elongate mounded drift within Q-II formed of: A) Transparent units at the base; B) Smooth, parallel reflectors of moderate-high amplitude units in the upper part; and C) An erosional continuous surface of high amplitude on the top of reflective units. This cyclicity in the acoustic response most likely represents cyclic lithological changes showing coarsening- upward sequences. A total of ten minor units has been distinguished within Q-II where the more representative facies in volume are always the more reflective and are prograding upslope with respect to the transparent ones. There is an important change in the overall architectural stacking of the mounded contourite deposits from a more aggrading depositional sequence (Q-I) to a clear progradational body (Q-II). We suggest that Q-I and Q-II constitute high-order depositional sequences related to a 3rd-order cycle at 800 ky separated by the most prominent sea-level fall at the Mid Pleistocene Revolution (MPR), 900–920 ky ago. In more detail the major high-order depositional sequences (from A to H) can be associated with asymmetric 4th-order climatic and sea-level cycles. In the middle slope, the contourite system has a syn-tectonic development with diapiric intrusions and the Guadalquivir Bank uplift. This syn-tectonic evolution affected the overall southern sheeted drift from the A to F depositional sequences, but G and H are not affected. These last two depositional sequences are less affected by these structures with an aggrading stacking pattern that overlaps the older depositional sequences of the Guadalquivir Bank uplift and diapiric intrusions.<br/
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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