1,720,984 research outputs found
Leontief meets Markov: Sectoral vulnerabilities through circular connectivity
Full text linkEconomists have been aware of the mapping between an Input-Output (I-O, hereinafter) table and the adjacency matrix of a weighted digraph for several decades (Solow, Econometrica 20(1):29–46, 1952). An I-O table may be interpreted as a network in which edges measure money flows to purchase inputs that go into production, whilst vertices represent economic industries. However, only recently the language and concepts of complex networks (Newman 2010) have been more intensively applied to the study of interindustry relations (McNerney et al. Physica A Stat Mech Appl, 392(24):6427–6441, 2013). The aim of this paper is to study sectoral vulnerabilities in I-O networks, by connecting the formal structure of a closed I-O model (Leontief, Rev Econ Stat, 19(3):109–132, 1937) to the constituent elements of an ergodic, regular Markov chain (Kemeny and Snell 1976) and its chance process specification as a random walk on a graph. We provide an economic interpretation to a local, sector-specific vulnerability index based on mean first passage times, computed by means of the Moore-Penrose inverse of the asymmetric graph Laplacian (Boley et al. Linear Algebra Appl, 435(2):224–242, 2011). Traversing from the most central to the most peripheral sector of the economy in 60 countries between 2005 and 2015, we uncover cross-country salient roles for certain industries, pervasive features of structural change and (dis)similarities between national economies, in terms of their sectoral vulnerabilities
Are there any relationships between osteoporosis and atherosclerosis in postmenopausal women?
No full textThe DECUS (Distance Education Catholic University System) Project: An on line Mathematics Course
No full textExtending assortativity: An application to weighted social networks
No full textAssortativity by degree for complex networks is quantified by the Newman coefficient, and it describes a tendency for nodes to be connected to others with a similar degree. A generalization of the assortativity index has been proposed in the literature for undirected and unweighted networks, analysing the correlation between vertices that are not necessarily adjacent, but connected through paths, shortest paths and random walks. The aim of this study is to define a new class of higher-order assortativity measures for weighted networks. The effectiveness of these measures is evident in social networks, where both weights and connections are significant. Applications to Facebook and co-authorship networks are provided, analysing the assortativity beyond the nearest neighbours
Kirchhoffian indices for weighted digraphs
Full text linkThe resistance indices, namely the Kirchhoff index and its generalisations, have undergone intense critical scrutiny in recent years. Based on random walks, we derive three Kirchhoffian indices for strongly connected and weighted digraphs. These indices are expressed in terms of (i) hitting times and (ii) the trace and eigenvalues of suitable matrices associated to the graph, namely the asymmetric Laplacian, the diagonally scaled Laplacian and their Moore–Penrose inverses. The appropriateness of the generalised Kirchhoff index as a measure of network robustness is discussed, providing an alternative interpretation which is supported by an empirical application to the World Trade Network
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
Inflammatory cytokines in fracture healing: involvement and analysis
Full text linkIntroductionThe importance of the interplay of both skeletal and immune systems is reflected by the emerging interdisciplinary research field, called osteoimmunology, focused on common aspects of osteology and immunology.
Many segnaling molecules, such as transcription factors, membrane receptors, IL-6 and TNF-α, are involved in the bone remodelling.
The purpose of this study was to evaluate markers of bone metabolism and cytokines in patients with fragility fractures compared to osteoporotic patients.
Materials and methods We enrolled 37 subjects with a femoral neck fracture and 47osteoporotic outpatients .
Blood samples are drawing 24h before and after surgery (Group A) and at the first examination for outpatients (Group B). All the patients underwent DEXA examination (T-score <-2.5) to measure BMD. For bone metabolism were measured Ca, P, vitamin D, PTH, CTX, ALP and osteocalcin using ECL technology (Modular E, Roche, Basel, Switzerland). IL-1, IL-6, TNF-α and IL-10 concentrations were evaluated by ELISA assay (R&D Systems, Inc. Minneapolis, USA). Statistical analysis were performed using t-test.
Results Statistical differences were observed in vitamin D, PTH and CTX concentrations. Group A showed a decrease in Vitamin D (p<0.001) whereas PTH and CTX were increase (p≤ 0.001).
About cytokine concentrations Group A (before surgery) showed a significant increase in IL-6, TNF-α and IL-10 (respectively p<0.0001, p<0.0001 and p=0.01) respect Group B.
The different implant used lead to a change, IL-6 and IL-10 increased after surgery in intramedullary nail patients Vs prosthesis, significant difference were respectively p<0.001 and p<0.05.
Discussion The inflammatory mediators are involved not only in several aspects of physiological bone remodeling but also in pathological bone disorders. The higher cytokines levels observed in fractured patients suggest an inflammatory condition which lead to bone weakness, this hypothesis may be supported by the results obtained in Vitamin D, PTH and CTX (1).
The results obtained in surgery treatment with prosthesis give a reduction in systemic cytokines concentrations. Inflammatory cytokines could be used to identify high-risk fracture patients, further study need to confirm their role in fracture healing.
1)Lacativa PG, Farias ML. Osteoporosis and inflammation. Arq Bras Endocrinol Metabol. 2010 Mar;54(2):123-32
2) Pacifici R. The immune system and bone. Arch Biochem Biophys. 2010 Jun 1
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