1,720,981 research outputs found
Repeated and Dynamic loading
No full textThe response of deep foundations to repeated dynamic loading has been a subject of considerable interest in recent years
in relation to the seismic design of important structures such as nucIear power plants, offshore structures and vibrating
machines, etc,
In spite of significant efforts on the part of theoretical and experimental researchers and the avai!ability of powerful
computers, because ofthe complex interaction effects in the superstructure-foundation-soi! system, and - more importantly
- the inelastic nature of the soil behaviour, exact solutions to the problem are stilI not available.
In current practice the engineer is necessarily faced with simplified, uncoupled, iterative procedures valid for specific
cases; the choice of a methodology associated with the definition of relevant soil properties is stilI fundamentaly empirica!.
The review ancl discussion of possible theoretical approaches are here mainly oriented toward their applicability and
shortcomings in light of the more recent experimental and theoretical developments.
Basic aspects related to geotechnical investigations and the cletennination of soil properties are pointecl out, as well as
the mai n factors that govern important phenomena such as clegraclation of soi! characteristics due to cycIic loacling ancl
clepenclence of stiffness ancl strength on rate of loading.
Advantages associated with the use centrifuge ancl full scale moclels both for research ancl for practical applications are
inclicatecl, especially in presence ofvery complex nonlinear boundary problems such as those representecl by large pile group
foundations
Five Years of Experience Using Palatal Mini-Implants for Orthodontic Anchorage
No full textPurpose: The authors review 5 years of clinical experience using Straumann Orthosystem (Straumann, Basel, Switzerland) palatal mini-implants for orthodontic anchorage, describe clinical procedures, and give statistical results.Materials and Methods: Diagnostic planning, surgical phase, and clinical procedure are described. The diagnostic planning was performed on lateral cephalogram, in 13 cases; in I case, with an ectopically included upper canine, a computed tomography was requested. The Straumann Orthosystem kit includes a pure titanium implant with the heating cap, and a set of burs and instruments for the surgical insertion and removal. The sample comprised 14 adult patients (2 males and 12 females) requiring fixed orthodontic appliance for Class H malocclusion. Because of critical anchorage conditions they had received a palatal mini-implant as absolute anchorage during orthodontic treatment: 9 implants of 6.0 mm and 7 implants of 4.0 mm were positioned, primarily using a 2.5 mm transmucosal neck length. The orthodontic phase always started after 13 weeks of the insertion, in order to ensure osteointegration.Results: In all cases, neither a perforation of the nasal cavity nor other surgical complication occurred. All implants have been successfully osteointegrated, except for I which has been lost for critical hygiene conditions. Two implants needed to be replaced because of tongue forces, which had been determined to interfere with the osteointegration immediately after surgery; this inconvenience was afterwards solved by the use of a resin splint.Conclusions: Palatal mini-implants revealed to be clinically easy to use and proved to be an efficient auxiliary device in orthodontics when absolute anchorage is needed. (c) 2007 American Association of Oral and Maxillofacial Surgeons
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
- …
