187,201 research outputs found
Monetary policy and the banking sector in Turkey
No full textWe find that monetary policy influenced Turkish bank lending between 1991 and 2007 through the money and bank lending channels. While capital and GDP growth have positive and significant long-run effects on bank loan growth, inflation, bank size and efficiency are not significant determinants. The latter is despite our finding that all Turkish banks' efficiency improved over the period. Domestic banks are unexpectedly found to be more efficient than foreign banks. With no evident dynamics or fixed-effects in loan growth we prefer the pooled-OLS estimator. We caution against assuming fixed-effects and dynamics are present as this may adversely affect inference. © 2013 Elsevier B.V
ON RAY SHOOTING IN CONVEX POLYTOPES
No full textLet P be a convex polytope with n facets in the Euclidean space of a (small) fixed dimension d. We consider the membership problem for P (given a query point, decide whether it lies in P) and the ray shooting problem in P (given a query ray originating inside P, determine the first facet of P hit by it). It was shown in [AM2] that a data structure for the membership problem satisfying certain mild assumptions can also be used for the ray shooting problem, with a logarithmic overhead in query time, Here we show that some specific data structures for the membership problem can be used for ray shooting in a more direct way, reducing the overhead in the query time and eliminating the use of parametric search. We also describe an improved static solution for the membership problem, approaching the conjectured lower bounds more tightly
Higher-order Erdos-Szekeres theorems
No full textLet P = (p1, p2,..., p N) be a sequence of points in the plane, where p i = (x i, y i) and x1 < x2 < ⋯ < x N. A famous 1935 Erdos-Szekeres theorem asserts that every such P contains a monotone subsequence S of ⌈N⌉ points. Another, equally famous theorem from the same paper implies that every such P contains a convex or concave subsequence of Ω (log N) points. Monotonicity is a property determined by pairs of points, and convexity concerns triples of points. We propose a generalization making both of these theorems members of an infinite family of Ramsey-type results. First we define a (k + 1) -tuple K ⊆ P to be positive if it lies on the graph of a function whose kth derivative is everywhere nonnegative, and similarly for a negative(k + 1) -tuple. Then we say that S ⊆ P is k th-order monotone if its (k + 1) -tuples are all positive or all negative. We investigate a quantitative bound for the corresponding Ramsey-type result (i.e., how large kth-order monotone subsequence can be guaranteed in every N-point P). We obtain an Ω (log (k -1) N) lower bound ((k - 1) -times iterated logarithm). This is based on a quantitative Ramsey-type theorem for transitive colorings of the complete (k + 1) -uniform hypergraph (these were recently considered by Pach, Fox, Sudakov, and Suk). For k = 3, we construct a geometric example providing an O (log log N) upper bound, tight up to a multiplicative constant. As a consequence, we obtain similar upper bounds for a Ramsey-type theorem for order-type homogeneous subsets in R3, as well as for a Ramsey-type theorem for hyperplanes in R4 recently used by Dujmović and Langerman. © 2013 Elsevier Ltd
Theoretical and Practical Considerations of Spatially Offset Raman Spectroscopy (SORS) and Micro-SORS
No full textSpatially offset Raman spectroscopy (SORS) is typically used to non-invasively investigate stratified samples that possess features on a millimeter scale, whereas micro-SORS usually deals with micrometer-thick layered samples. However, there are many instances where these boundaries are intertwined, sometimes indicating the possibility of using both techniques as well as circumstances that present mutual exclusion to their applicability. The aim of this study is to establish an application protocol that provides better insight into their suitability for deployment in various scenarios. The differences and similarities between the two approaches are investigated highlighting their strengths and limitations considering both theoretical and practical aspects. Diverse available parameters entail prospects and restrictions of both techniques and give rise to specific instrumental effects, namely, the overlap between the collection and excitation areas, the percentage of collected area for a given spatial offset, and the accuracy in the definition of the spatial offset (spread effect). These aspects are studied and exemplified on mockup samples relevant to the field of cultural heritage. The samples are characterized by high compositional complexity comprising features ranging from micrometer to millimeter scales. The conclusions reached are also relevant to other scientific areas such as biomedical, forensic, or energy harvest
Financial centres' competitiveness and economic convergence: Evidence from the European Union regions
No full textThis study analyses the gaps in financial centres' competitiveness and their impact on regional economic convergence in 23 European Union Member States during the period of the Global Financial Crisis. In particular, we explore the economic convergence and divergence patterns among regions from two different perspectives across the selected European Union Member States and within each country. From a methodological viewpoint, we apply a fully non-parametric framework to the club convergence model and address the endogeneity problem between financial centres' competitiveness and regional economic convergence. Our results show that the large and internationally-oriented financial centres experienced a diverging trend in terms of the competitiveness of financial centres' business environment during the peak of the crisis. We also find evidence that the convergence of financial centres reduces regional economic inequalities between the regions where financial centres are located. In contrast, the increase in the competitiveness of financial centres only serves to widen existing inequalities at the national level. Finally, we examine and discuss the impact of competitiveness drivers of financial centres on the convergence pattern of European Union regions.</p
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Non-destructive analysis of concentration profiles in turbid media using micro-spatially offset Raman spectroscopy: A physical model
No full textWe introduce an analytical physical description of micro-spatially offset
Raman spectroscopy (micro-SORS) experiments in turbid samples with a spe-
cial emphasis on its use for studying the penetration depth of chemical species
(agents) into a matrix. Such samples exhibit varying concentration gradients
with depth and reflect typical situations encountered in Cultural Heritage
framework. The experiments aim at yielding the variations (trends) of the
Raman intensity ratio of the agent and matrix marker bands, H Xð Þ, with
increasing micro-SORS defocusing distance Xð Þ. The physical model shows
that H Xð Þ can be expressed as a function of the concentration profiles of the
analytes. The analysis makes use of Monte Carlo simulation results of the
propagation of photons in turbid media. Despite the introduced approxima-
tions, the obtained formulas provide an insightful tool that allows justifying
the observed trends and facilitates the interpretation of micro-SORS data and
systematic comparison among different samples. Basic comparison with
previously published experimental micro-SORS data indicates good consis-
tency. The obtained relationships could also be useful for a semi-quantitative
estimate of concentration profiles in unknown sample
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
Nucleon spin structure studies in Drell–Yan process at COMPASS
No full textThe nucleon structure is presently described by Transverse Momentum Dependent (TMD) Parton Distribution Functions (PDFs), which generalise the collinear PDFs, adding partonic spin and transverse momentum degrees of freedom. The recent HERMES and COMPASS data on hadron production in deep inelastic scattering (SIDIS) of leptons off transversely polarised nucleons have provided a decisive validation of this framework. Nevertheless, the TMD PDFs should be studied in complementary reactions, like pp hard scattering and Drell-Yan processes. In particular the Sivers TMD PDF, which encodes the correlation between the nucleon spin and quark transverse momentum and appears in the Sivers Transverse Spin Asymmetry (TSA), is expected to have opposite sign in DY and SIDIS. In 2015 COMPASS measured for the first time the Drell-Yan reaction pi- p↑ → mu- mu X to test this prediction and the results have been recently published. The main topic of the thesis is the first measurement of the TSAs weighted with the dimuon transverse momentum in this data. These asymmetries complement the conventional TSAs and their advantage is that they do not contain convolutions over intrinsic transverse momenta. My analysis work is described in detail and the results are compared with calculations based on the extraction of the Sivers function from the recently measured weighted Sivers asymmetry in SIDIS. The thesis also contains a theoretical introduction, the description of the apparatus focused on the polarised target and its monitoring system to which I contributed. Finally, a chapter dedicated to the first original analysis in my PhD, the measurement of a Sivers-like asymmetry in the J/psit production in SIDIS, which is related to the gluon Sivers function, is included as well
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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