125,404 research outputs found
Quantum Eberlein compactifications and invariant means
No full textWe propose a definition of a "-Eberlein" algebra, which is a weak form of a -bialgebra with a sort of "unitary generator". Our definition is motivated to ensure that commutative examples arise exactly from semigroups of contractions on a Hilbert space, as extensively studied recently by Spronk and Stokke. The terminology arises as the Eberlein algebra, the uniform closure of the Fourier-Stieltjes algebra , has character space , which is the semigroup compactification given by considering all semigroups of contractions on a Hilbert space which contain a dense homomorphic image of . We carry out a similar construction for locally compact quantum groups, leading to a maximal -Eberlein compactification. We show that -Eberlein algebras always admit invariant means, and we apply this to prove various "splitting" results, showing how the -Eberlein compactification splits as the quantum Bohr compactification and elements which are annihilated by the mean. This holds for matrix coefficients, but for Kac algebras, we show it also holds at the algebra level, generalising (in a semigroup-free way) results of Godement
On pricing risky loans and collateralized fund obligations
No full textLoan spreads are analyzed for two types of loans. The first type takes losses at maturity only; the second follows the formulation of collateralized fund obligations, with losses registered over the lifetime of the contract. In both cases, the implementation requires the choice of a process for the underlying asset value and the identification of the parameters. The parameters of the process are inferred from the option volatility surface by treating equity options as compound options with equity itself being viewed as an option on the asset value with a strike set at the debt level following Merton. Using data on the stock of General Motors during 2002-3, we show that the use of spectrally negative Lévy processes is capable of delivering realistic spreads without inflating debt levels, deflating debt maturities or deviating from the estimated probability laws
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Quantum Eberlein compactifications and invariant means
No full textWe propose a definition of a "C∗-Eberlein" algebra, which is a weak form of a C∗-bialgebra with a sort of "unitary generator". Our definition is motivated to ensure that commutative examples arise exactly from semigroups of contractions on a Hilbert space, as extensively studied recently by Spronk and Stokke. The terminology arises as the Eberlein algebra, the uniform closure of the Fourier-Stieltjes algebra B(G), has character space GE, which is the semigroup compactification given by considering all semigroups of contractions on a Hilbert space which contain a dense homomorphic image of G. We carry out a similar construction for locally compact quantum groups, leading to a maximal C∗-Eberlein compactification. We show that C∗-Eberlein algebras always admit invariant means, and we apply this to prove various "splitting" results, showing how the C∗-Eberlein compactification splits as the quantum Bohr compactification and elements which are annihilated by the mean. This holds for matrix coefficients, but for Kac algebras, we show it also holds at the algebra level, generalising (in a semigroup-free way) results of Godement
Dispelling the Myths Behind First-author Citation Counts
No full textWe 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
Structure of the Eberlein compactification of locally compact Heisenberg type group ZxTxT
No full textGiven a locally compact group G, the Eberlein compactification G(e) is the spectrum of the uniform closure of the Fourier-Stieltjes algebra B(G). Hence, it is the semigroup compactification related to the unitary representations of G. G(e) is a semitopological semigroup compactification and thus a quotient of the weakly almost periodic compactification of G. In this paper we aim to study the Eberlein compactification of the group ZxTxT equipped with Heisenberg type multiplication. First, we will see that transitivity properties of the action of ZxT on the central subgroup T force some aspects of the structure of (ZxTxT) to be quite simple. On the other hand, we will observe that the Eberlein compactification of the direct product group ZxT is large with a complicated structure, and can be realized as a quotient of the Eberlein compactification (ZxTxT)(e)
Reply to Eberlein et al.
No full textWe thank Eberlein et al. [1] for their interest in our article [2]. The purpose of our study [2] was not to show that oversized grafts are associated with more perioperative complications and worse outcome compared with standard lung transplantation. In our experience, oversized lung grafts can potentially lead to atelec-tasis and impaired airway clearance, which leads to a more complicated postoperative course [3]. Optimal size matching is therefore very important. For optimal size matching, different methods have been proposed, such as donor-recipient differ-ence or ratio of body weight and height [4, 5]. In addition, chest circumference and chest x-ray vertical and transverse dimensions have been used [4]. Others have used donor and recipient total lung capacity (TLC) [4, 5]. Interestingly, a recent US study showed that overall post-transplant survival or lung func-tion after standard lung transplantation was unaffected b
Pragmatic Case Studies as a Source of Unity in Applied Psychology
No full textTo unify or not to unify applied psychology: that is the question. In this article we review pendulum swings in the historical efforts to answer this question—from a comprehensive, positivist, “top-down,” deductive yes between the 1930s and the early 60s, to a postmodern no since then. A rationale and proposal for a limited, “bottom-up,” inductive yes in applied psychology is then presented, employing a case-based paradigm that integrates both positivist and postmodern themes and components. This paradigm is labeled “pragmatic psychology” and, its specific use of case studies, the “Pragmatic Case Study Method” (“PCS Method”). We call for the creation of peer-reviewed journal-databases of pragmatic case studies as a foundational source of unifying applied knowledge in our discipline. As one example, the potential of the PCS Method for unifying different angles of theoretical regard is illustrated in an area of applied psychology, psychotherapy, via the case of Mrs. B. The article then turns to the broader historical and epistemological arguments for the unifying nature of the PCS Method in both applied and basic psychology.Peer reviewe
Dr. Edwin Wright Collection: Author Unknown
No full textNotes - The author relates several short stories about his neighbours including Alex McDonell, homesteading and life around Meanook and Athabasca (1 page
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe 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
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