1,721,007 research outputs found
Estimation of railway projects duration at initiating phase: a statistic approach
No full textIn Large Transportation Projects (LTPs) estimation of duration provided in tender and initiating phase are often contradicted in executing phase, due to a mix of technical and contractual problems arising during the project execution. This paper present a research that apply a statistic approach to this problem and, determining the key features of a LTP and a set of hi storic data coming from the railway field, present a quantitative solution. The first part of the paper makes an analysis of existing literature on this topic, then the methodology is discussed. In the second part, a statistical model is presented, to show how the set of identified relevant variables are used to estimate the duration according to project features avoiding other goals such as political goals of cutting the project duration. In fact, the common sense of technical advisers is that the duration of a project is often given by non -technical goals, but the drivers are more referred to a specific deadline such as elections or large public events (World Cups, Universal Exposition etc.), asking to cut and cut time and, as a result, projects become more expensive, hard to manage, and face technical problems in the operating phase. In the third part, this method is calibrated on a set of input coming from real railway LTPs of the last ten years. The aim of this paper is to let the decision makers know that, given a new project, the past experience says that it will have a given duration according to its features, and to ask for a shorter project duration would be risky and cause project failure, or let the project cost rise. It also allow to define a guideline to determine which contractual form is the best according to t he project
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
FORECASTING THE SUCCESS OF HYPERLOOP TECHNOLOGY ON ITALIAN ROUTES: A BROAD FEASIBILITY STUDY
No full textLarge Infrastructure Projects, also referred as Large Engineering Projects
(or LEPs), are always controversial due to the fact that standard cost-benefit
analysis and other economic evaluations are often negative due to their high implementation
cost and their high level of risk related the uncertainty and innovation
they bring with them.
Anyway, in the last decades, the investment on LEPs in increasing all over the
world (Flyvjierg, B., 2014), and the construction of LEPs is still considered a basic
leverage to increase the wealth of nations. The topic is particularly relevant at EU
level. In fact the decision-making process on which infrastructure (LEP) should be
funded and which not by the public sector has been criticized by new “sovranist”
political parties. For example, studies both in favor and against the funding of the
same infrastructure have been published by different academics, even belonging to
the same institution (Ponti, M. et al., 2019) (Cantarella G.E., et al., 2019).
In the last few months there is a lot of discussion in Italy about the feasibility of an
Hyperloop, that is a “Hyperloop is a sealed tube or system of tubes through which
a pod may travel free of air resistance or friction conveying people or objects at
high speed while being very efficient, thereby drastically reducing travel times over
medium-range distances” (Opgenoord, Max M.J., 2019). In particular, six possible
route have been drafted, e.g. Milan-Rome, Milan Cadorna Station-Milan Malpensa
Airport, Verona-Trieste and others.
The Authors want to evaluate the economic feasibility of that revolutionary transpiration
mode, applying a broad approach, according both the indications of the
European Commission's Guide to Cost-Benefit Analysis of Investment Projects
(2014), including both ordinary costs and benefits, and evaluation also the innovation
benefits that such transportation mode, if implemented, will bring: evaluating
such a transportation mode as, for example, an ordinary high speed train mode,
won’t be correct, because implementing it will cause innovation in several technologic
fields and in the transportation sector as a whole, and these benefits must be
encompassed in the analysis. In addition, the authors will evaluate other success
criteria such as the one indicated by Atkinson, R. (1999), i.e. “stakeholder benefits
against which projects can be assessed”. Including the approach by Turner and
Zolin (2012) of taking into account multiple perspectives by multiple stakeholders
over multiple time frames: In Large Engineering Projects “How different stakeholders
perceive success can change with time, and so the project manager needs
leading performance indicators that go beyond the traditional triple constraint to forecast how key stakeholders will perceive success months or even years later”
(Turner and Zolin, 2012).
This research has the aim of carrying out a preliminary technical-economic feasibility
study of a potential Hyperloop line connecting the cities of Rome and Milan,
chosen as they are poles of attraction and generators of transportation demand.
The main objective is not to analyze the validity of the technology used as to assess
the feasibility and sustainability of such a project.
The first section briefly describes the history and technology, the main characteristics
and limitations of these vehicles. The second section presents a transportation
study of the potential demand through surveys that will make it possible to identify
users' preferences, assessing the transportation demand and the willingness to
pay of potential users. In the third and fourth sections a financial and economic
analysis is performed, presenting assumptions and limitations that this research
necessarily has, due to the lack of information on several areas. In the last section
before conclusions, some consideration is made about the possible social impact on
potential stakeholders involvement, presenting also preliminary feedback from interviews
to industrial stakeholder that are considering their involvement in a hyperloop
venture in Italy. In the last section, the Authors make a balance of their
findings and outline the further development of the research on this topic
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
The C-terminal domain of apolipoprotein A-I is involved in ABCA1-driven phospholipid and cholesterol efflux
No full textABCA1, a member of the ATP-binding cassette family, mediates the efflux of cellular lipids to free apolipoproteins, mainly apoA-I. The role of the C-terminal domain of apoA-I in this process has been evaluated by measuring the efflux capacity of a truncated form (apoA-I-(1-192)) versus intact apoA-I in different cellular models. In stimulated J774 macrophages, cholesterol efflux to apoA-I-(1-192) was remarkably lower than that to the intact apoA-I. The truncated apoA-I, lacking an important lipid-binding domain, was also significantly less efficient in removing phospholipids from stimulated macrophages. No difference was detected with stimulated Tangier fibroblasts that do not express functional ABCA1 The C-terminal domain of apoA-I is clearly involved in ABCA1-driven lipid efflux. Independent of the interaction with the cell surface, it may be the decreased ability of the truncated apoA-I to recruit membrane phospholipids that impairs its capacity to promote cell cholesterol efflux. (C) 2002 Elsevier Science (USA). All rights reserved
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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