1,721,500 research outputs found
L’analisi statistica bivariata in ambiente GIS: un esempio applicato alla valutazione della suscettibilità da frana
No full textValutare la probabilità di accadimento dei
movimenti di massa e gli effetti che ne conseguono, significa,
in termini tecnico-scientifici, stimarne il grado
di suscettibilità, pericolosità e rischio per una determinata
area. Il riconoscimento e la perimetrazione delle
aree a differente grado di pericolosità, quando siano il
risultato dei tradizionali metodi di osservazione e di fotointerpretazione,
possono contenere una percentuale
d’errore variabile e talvolta consistente (fino all’80%).
Questo rende le carte tematiche, derivanti dalle consuete
tecniche di rilevamento, estremamente soggettive e non
sempre attendibili. La crescente diffusione dei Sistemi
Informativi Geografici (GIS) e delle immagini satellitari,
ha fornito la possibilità di utilizzare nuovi strumenti,
validi sia per il riconoscimento delle forme, che per la
perimetrazione, attraverso modelli di analisi spaziale,
delle aree soggette a specifici processi morfogenetici.
Il lavoro presenta un esempio di valutazione della
suscettibilità da frana applicato al bacino del T. Assino
(Umbria) attraverso un modello di analisi statistica bivariata.
La carta finale di sintesi è il risultato di complesse
operazioni di acquisizione, pre-elaborazione e analisi dei
dati territoriali sintetizzabili come di seguito:
1) implementazione di un DBR (Database Relazionale)
dei fattori della franosità dell’area: geologia, uso del suolo,
caratteristiche morfometriche e morfologiche significative;
2) analisi di un DEM (Digital Elevation Model) a 90 m di
risoluzione derivato da dati SAR per l’elaborazione degli attributi topografici primari e secondari selezionati;
3) individuazione di unità omogenee (UCU);
4) determinazione e successiva digitalizzazione in ambiente GIS delle aree in dissesto per comprendere i rapporti spaziali e causativi tra frequenza e distribuzione per ogni fattore predisponente;
5) operazioni di overlay dei fattori pesati, per la realizzazione di una cartografia di sintesi con la perimetrazione di aree a grado di pericolosità crescente
A morphometric model of lung mechanics for time-domain analysis of alveolar pressures during mechanical ventilation
No full textIn this study we propose, and implement in the time domain, an anatomically consistent model of the respiratory system in critical care conditions that allows us to evaluate the impact of different ventilator strategies as well as of constrictive pathologies on the time course of acinar pressures and flows. We discuss the simplifications of the original Horsfield structure (Horsfield, K., et al. Models of the human bronchial tree. J. Appl. Physiol. 31:207-217, 1971), which were needed to enable the model implementation. The model has a binary tree structure including large airways represented as a combination of wall compliance and laminar resistance, small airways that have the same arrangement but can be heterogeneously constricted, and alveolar compartments that are viscoelastic second-order models to represent the stress adaptation behavior of lung tissue. We have described patient-ventilator interactions modeling the ventilator and the endotracheal tube. In conclusion this model makes it possible to investigate realistically the effect of homogeneous versus heterogeneous constrictive pathologies and the impact of different ventilatory patterns on pressure and flow distribution at the acinar level in the mechanically ventilated patient
The subcutaneous route to insulin-dependent diabetes therapy
No full textDiscusses closed-loop and partially closed-loop control strategies for insulin delivery and measuring glucose concentration. The authors review the subcutaneous closed- and partially closed-loop strategies that have been proposed and tested in recent years for insulin-dependent diabetes therapy. Focus is on control, modeling, and information technology aspects, and future directions of research are also outlined. This survey complements earlier reviews concerning control approaches and application of computers in diabetes car
Models of subcutaneous insulin kinetics. A critical review
No full textSubcutaneous insulin kinetics is a complex process whose quantitation is needed for a reliable glycemic control in the conventional therapy of insulin-dependent diabetes. The major difficulties in modeling include accounting for the distribution in the subcutaneous depot and transport to plasma. A single model describing in detail the various processes for all the commercially available insulin preparations is not available. Several models however have been proposed which vary in the degree of complexity. Virtually all of them handle the regular insulin preparation while a few handle the intermediate acting and the novel insulin analogues. In this paper we critically review these models
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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