1,720,988 research outputs found
2.2 L’approccio morfologico-sedimentario nello studio della dinamica fluviale
No full textViene illustrata una metodologia di indagine ed analisi dei sistemi fluviali basata su un approccio morfologico-sedimentario, cioè sul rilevamento puntuale dei caratteri geomorfologici e sedimentari degli alvei fluviali e della loro pianura alluvionale. L'obiettivo consiste nell'individuazione dei processi di dinamica fluviale in atto e della tendenza evolutiva del sistema; tale "conoscenza" costituisce la base imprescindibile per la definizione dei corretti criteri di intervento e di gestione del sistema fluviale, finalizzati, da una parte, all'utilizzazione sostenibile della risorsa, dall'altra alla mitigazione del rischio geologico-idraulico. Sono infine riportati alcuni casi di studio
Il sorting verticale dei sedimenti: implementazione in GRASS GIS di un modello di predizione e test sperimentali.
No full textLandslide dams indotte da debris flows nella Cordillera Oriental delle Ande (Argentina nord-occidentale).
No full textLa "Quebrada de Humahuaca". Aspetti geomorfologici di un bacino di ambiente andino
No full textSono descritti nella nota i principali elementi geologici e geomorfologici di un bacino, situato nelle Ande Argentine, la Quebrada de Humahuaca, che rappresenta la porzione di monte di un bacino idrografico più ampio, quello del Rio Grande de Jujuy. L'influenza degli elementi litologici e strutturali sulle forme del rilievo si accompagna a un forte condizionamento climatico (di tipo sub-arido). Il risultato è che i processi di movimenti di massa, del tipo colate detritiche, che si verificano in concomitanza con i rari, anche se concentrati, eventi pluviometrici, rappresentano uno dei più importanti processi morfogenetici, determinando anche la presenza di condizioni di rischio per le infrastrutture ivi esistenti (Ferrocarril G.ral Belgrano e Ruta Panamericana) che costituiscono le uniche vie di collegamento terrestre con la vicina Bolivia
A GRASS GIS application for vertical sorting of sediments analysis in River Dynamics
No full textThe extreme versatility in different research fields of GRASS GIS is well known. A tool for the vertical sorting of sediments in river dynamics analysis is illustrated in this work. In particular, a GRASS GIS python module has been written which implements a forecasting sorting model by Blom & Parker (2006) to analyze river bed composition’s evolution in depth in terms of grain size. The module takes a DEM and information relative to the bed load transport composition as input. It works in two different and consecutive phases: the first one uses the GRASS capabilities in analyzing geometrical features of the river bed along a chosen river reach, the second phase is the "numerical" one and implements the forecasting model itself, then executes statistical analyses and draws graphs, by the means of matplotlib library. Moreover, a specific procedure for the import of a laser scanner cloud of points is implemented, in case the raster DEM map is not available. At the moment, the module has been applied using flumes data from Saint Anthony Falls Laboratory (Minneapolis, MN) and some first results have been obtained, but the "testing" phase on other flume’s data is still in progress. Moreover the module has been written for GRASS 65 on a Ubuntu Linux machine, even if the debugging of a GRASS 64, Windows version, is also in progress. The final aim of this work is the application of the model on natural rivers, but there are still some drawbacks. First of all the need of a high resolution DEM in input, secondly the number and type of data in input (for example the bed load composition in volume fraction per each size considered) which is not easily obtainable, so the best solution is represented by testing the model on a well instrumented river reach to export in future the forecasting method to un-instrumented reaches
Esperienze di rilevamento e determinazione dei caratteri granulometrici di alvei ghiaiosi.
No full textIl presente studio analizza e mette a confronto alcuni metodi di campionamennto tradizionale dei sedimenti d'alveo, applicati nell'ambito di una campagna di rilevamento geomorfologico-sedimentario del torrente Virginio presso Baccaiano, nel comune di Montespertoli (FI). Viene, inoltre, introdotto un metodo sperimentale di acquisizione ed elaborazione di immagini digitali per l'analisi delle granulometrie a video. Tale valutazione, effettuata tramite l'ausilio di metodi quantitativi riportati in letteratura, ha evidenziato che la tecnica di campionamento tramite griglia (grid by number) può essere considerata una valida alternativa al metodo volumetrico, soprattutto se applicata ad alvei ghiaiosi, analoghi al torrente Virginio, caratterizzati da depositi alquanto grossolani. Infatti il grid by number, oltre a presentare evidenti vantaggi dal punto di vista pratico, è meno soggetto a problemi inerenti la significatività del campionamento che possono rendere estremamente difficoltoso il metodo volumetrico. Il metodo fotografico, sebbene necessiti di essere testato ulteriormente, ha fornito risultati molto incoraggianti. Pertanto è possibile ipotizzare un suo utilizzo per tutti quei casi in cui le risorse a disposizione non consentono di effettuare costose e lunghe campagne di campionamento "hand sampling"
Characterization of Upper Limb Motor Dysfunctions in Spinocerebellar Ataxia 38: Kinematic Analysis of the “Hand-to-Mouth” Task
No full textIndividuals affected by spinocerebellar ataxia 38 (SCA 38) progressively lose the ability to efficiently perform important activities of daily living involving the use of upper limbs, like personal care and feeding. However, it is important to note that data on the extent of upper limb motor dysfunction in SCAs are generally limited, and specifically, no information is currently available for SCA38-particularly in the context of performing functional tasks. To partly fill this gap, in this study we analyze the kinematic features of the Hand-to-Mouth task in 7 individuals with SCA 38 and an equally sized group matched for age and sex using an optical motion capture system, by analyzing performance, stability and smoothness parameters based on the 3D hand trajectory. The results show that, in comparison with unaffected individuals, those with SCA 38 required longer time to complete the task, especially during the going phase towards the mouth, perform more adjustment in proximity of the target and their movement results more fragmented and less smooth. Such findings provide new and relevant insights regarding the upper limb residual functions under 'real-life' conditions in SCA 38, and represent a complementary tool to the usual clinical assessment to support better monitoring the disease progression as well as the design of specific tailored therapeutic interventions
The fluvial dynamics of the Arno River - 4. Map of the morphological-sedimentary and human characteristics of the Arno river bed and alluvial plain (Table 7 “MONTEVARCHI”).
No full textThe results of a survey of the morphological-sedimentary and human characteristics of the Arno River bed and plain of the upper Valdarno, including the confluence of the Ambra Creek and St. Giovanni Valdarno, are reported by means of a thematic map at 1:10,000 scale. In this stretch, the river flows in an almost straight line with alternate side bars, within a plain having an average width of 1 to 2 kilometers. The present planimetric form of the river bed derives from the number of training works and canalisations undertaken in this section from the beginning of the 17th century, and which have caused, as the most visible consequence on the morphology of the course, a noticeable reduction in the width of the bankfull channel (from 300-500 metres to the present 150 metres), and the disappearance of interlacement, which was very frequent before 1700. During recent decades, the morphological and sedimentary characteristics of the river have been strongly influenced by intense gravel extraction, and by the construction of the artificial lakes of Levane and La Penna immediately upstream. These factors have certainly influenced the sedimentary equilibrium of the river, causing or encouraging erosive phenomena: the river is affected by a notable lowering of its bed, while the planimetric activity is very limited since there is hardly an erosion of the banks. The sedimentary bodies have a low mobility and a tendency to remain "suspended" with respect to the present level of the low waters. The sedimentary characteristics of the river bed are also considered in this paper and are graphically documented: the river is gravelly, with the average diameter of the material being between -3 and -6 phi. The bank protection works grant the river bed an elevated planimetric stability. On the other hand, the lowering process of the bed has made consolidation work on existing bridges necessary. The construction of a dam by E.N.E.L. has contributed to an altimetric fixation of the river bed bottom. The main aquifers present in the alluvial plain are distributed in correspondance to the coarse flood material, especially along the ancient river bed. Usually, the groundwater is affected by a field of motion which converges towards the river and which seems to be fed by them, except for local and temporary inversions of the groundwater-river relationships, especially in those areas with a greater water withdrawal. As far as the risk of flooding is concerned, this paper is limited to reporting the situation after the flood of November 4, 1966 (the maximum flow was reached in Montevarchi: 2,580 m^3/sec). On this occasion however, the tributaries caused the most damage. The flooded area of 1966 can only give us an indication of the areas which are more at risk of flooding should the same conditions repeat themselves, even if one must consider that some of the tributaries have undergone works of reinforcement, bridling and raising of the embankments. Only a few points of localised flooding have remained more or less unchanged, for example around bridges
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
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