1,721,007 research outputs found
An Algebraic Characterization of O-Minimal and Weakly O-Minimal MV-Chains
No full textWe present an algebraic characterization of both o-minimal and weakly o-minimal
MV-chains by showing that a linearly ordered MV-algebra is (1) o-minimal if and only if it
is finite or divisible, and (2) weakly o-minimal if and only if its first-order theory admits
quantifier elimination in a suitable language if and only if Rad(A) is a divisible monoid
and A/Rad(A) is either finite or divisible
Quantifier elimination and other model-theoretic properties of BL-algebras
No full textThis work presents a model-theoretic approach to the study of first-order theories of classes of BL-chains. Among other facts, we present several classes of BL-algebras, generating the whole variety of BL-algebras, whose first-order theory has quantifier elimination. Model-completeness and decision problems are also investigated. Then we investigate classes of BL-algebras having (or not having) the amalgamation property or the joint embedding property and we relate the above properties to the existence of ultrahomogeneous models
Applicazione della tecnica perfusione MRI nella valutazione del grado di malignità dei gliomi cerebrali
No full textIn the cerebral gliomas clinical practice, correct grading is really important. Establishing the correct lesion’s malignancy
degree has relevant clinical implications, in terms of outcome and therapeutic strategies.
Histopathologicalogical evaluation of cerebral gliomas sometime is difficult because of the impossibility of surgery
or sampling mistakes, and imaging study with Magnetic Resonance provides morphological important information,
but not so reliable for malignancy. During last years, there has been a considerable development of advanced RM techniques, which completes anatomy information, providing precious indications about the functionality
of the investigated lesions. Perfusion represents the direct measure of the microvascularization of a tissue
and can be used as a marker of imaging to estimate the tumor angiogenesis and the degree of malignancy.
Our work aimed at evaluating the role of MR perfusion in establishing the correct grade of cerebral gliomas: we
analysed perfusion maps of 22 patients affected by low grade or high grade gliomas, with or without histological
confirmation, and after that we compared among tumor degrees II, III, IV and between simplified grade (low grade
gliomas and high grade gliomas) with the main parameters of perfusion CBV (Cerbral Blood Volume) e CBF (Cerebral
Blood Flow). A positive correlation has been found out between the two parameters and between the parameters
and the cancer degree and this means that the bigger the degree of malignancy, the greater the perfusion is. This
agrees with the histological datum that shows that the more consistent the vascularization, the more malignant the
lesion is. It has been possible distinguishing between high grade gliomas and low grade gliomas throw the perfusion
parameters, but it has not been possible to make a distinction between II/III and III/IV, because of the low
number of patients suffering from grade III gliomas. Therefore, perfusion MR study might represent a useful instrument
for the differential diagnosis between HGG and LGG, with relevant implications in the follow-up too. It’s
still necessary to evaluate the discriminating power of the technique in the intermediate grade tumor
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
Telomeric nucleosomes are intrinsically mobile
No full textNucleosomes are no longer considered only static basic units that package eukaryotic DNA but they emerge as dynamic players in all chromosomal processes. Regulatory proteins can gain access to recognition sequences hidden by the histone octamer through the action of ATP-dependent chromatin remodeling complexes that cause nucleosome sliding. In addition, it is known that nucleosomes are able to spontaneously reposition along the DNA due to intrinsic dynamic properties, but it is not clear yet to what extent sequence-dependent dynamic properties contribute to nucleosome repositioning. Here, we study mobility of nucleosomes formed on telomeric sequences as a function of temperature and ionic strength. We find that telomeric nucleosomes are highly intrinsically mobile under physiological conditions, whereas nucleosomes formed on an average DNA sequence mostly remain in the initial position. This indicates that DNA sequence affects not only the thermodynamic stability and the positioning of nucleosomes but also their dynamic properties. Moreover, our findings suggest that the high mobility of telomeric nucleosomes may be relevant to the dynamics of telomeric chromatin. (C) 2007 Elsevier Ltd. All rights reserved
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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