267,395 research outputs found
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
B-c meson production at the Tevatron revisited
No full text[[abstract]]CDF recently measured the quantity sigma(B-c(+))/sigma(B+) BR(B-c(+)-->J/psi l(+) upsilon)/BR(B+-->J/psi K+), from which we determine the ratio sigma(B+)/sigma((b) over bar) to be (2.08(-0.95)(+1.06)) X 10(-3). In this note, we show that the ratio sigma(B-c(+))/sigma((b) over bar) obtained by dividing the sigma(B-c(+)) by the leading order sigma((b) over bar) is consistent with this derived CDF measurement. We calculate the cross section sigma(B-c(+)) using the perturbative QCD fragmentation functions of Braaten, Cheung, and Yuan and the corresponding induced gluon fragmentation functions, with the charm-quark mass m(c) as a parameter. We also estimate the parameter m(c) from the CDF data and then predict the production rate at RunII.[[fileno]]2010134010034[[department]]物理
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
A systematic approach to atomicity decomposition in Event-B
No full textEvent-B is a state-based formal method that supports a refinement process in which an abstract model is elaborated towards an implementation in a step-wise manner. One weakness of Event-B is that control flow between events is typically modelled implicitly via variables and event guards. While this fits well with Event-B refinement, it can make models involving sequencing of events more difficult to specify and understand than if control flow was explicitly specified. New events may be introduced in Event-B refinement and these are often used to decompose the atomicity of an abstract event into a series of steps. A second weakness of Event-B is that there is no explicit link between such new events that represent a step in the decomposition of atomicity and the abstract event to which they contribute. To address these weaknesses, atomicity decomposition diagrams support the explicit modelling of control flow and refinement relationships for new events. In previous work, the atomicity decomposition approach has been evaluated manually in the development of two large case studies, a multi media protocol and a spacecraft sub-system. The evaluation results helped us to develop a systematic definition of the atomicity decomposition approach, and to develop a tool supporting the approach. In this paper we outline this systematic definition of the approach, the tool that supports it and evaluate the contribution that the tool makes
Branching fraction and CP asymmetry of the decays B+→K0Sπ+ and B+→K0SK+
No full textAn analysis of B+ → K0
Sπ+ and B+ → K0
S K+ decays is performed with the LHCb experiment. The pp
collision data used correspond to integrated luminosities of 1 fb−1 and 2 fb−1 collected at centre-ofmass
energies of
√
s = 7 TeV and
√
s = 8 TeV, respectively. The ratio of branching fractions and the
direct CP asymmetries are measured to be B(B+ → K0
S K+
)/B(B+ → K0
Sπ+
) = 0.064 ± 0.009 (stat.) ±
0.004 (syst.), ACP(B+ → K0
Sπ+
) = −0.022 ± 0.025 (stat.) ± 0.010 (syst.) and ACP(B+ → K0
S K+
) =
−0.21 ± 0.14 (stat.) ± 0.01 (syst.). The data sample taken at
√
s = 7 TeV is used to search for
B+
c
→ K0
S K+ decays and results in the upper limit ( fc · B(B+
c
→ K0
S K+
))/( fu · B(B+ → K0
Sπ+
)) <
5.8 × 10−2 at 90% confidence level, where fc and fu denote the hadronisation fractions of a ¯b
quark
into a B+
c or a B+ meson, respectively
Supplementary Table S3. Orthologous gene identification by blastp in B. deweyae B1 of the 24 most studied virulence factors reported by Nicholas Cheung et al. in 2020.
No full textSupplementary Table S3. Orthologous gene identification by blastp in B. deweyae B1 of the 24 most studied virulence factors reported by Nicholas Cheung et al. in 2020
Nitric oxide mediates the neuroproliferative effect of Neuropeptide Y
No full textNeuropeptide Y (NPY) is widely expressed in both the central and peripheral nervous system and has an important role in the regulation of adult hippocampal neurogenesis by mediating the proliferation of neural precursor cells in both health and disease. The mechanisms underlying this neuroproliferative effect of NPY, however, are unknown. The aim of this project was to investigate these cellular pathways and the possible involvement of nitric oxide (NO) in NPY-mediated neuroproliferation using postnatal rat hippocampal cultures in vitro. NPY was found to have a purely proliferative effect on hippocampal neural precursor cells. The role of NO was explored by inhibiting the NO synthesising enzyme, nitric oxide synthase (NOS), which abolished the proliferative effect of NPY and supported the involvement of NO in NPY-mediated proliferation. Pharmacological analyses using subtype-selective inhibitors suggested that the neuronal isoform of NOS is the sole NOS subtype involved, which was expressed by both nestin+ precursors and class III ?-tubulin+ neurons, the cell types previously shown to be responsive to NPY. The involvement of NO was further verified through loading hippocampal cells with an NO indicator, diaminofluorescein diacetate, where an increase in NO/N2O3 production was observed in nestin+ precursors and class III ?-tubulin+ neurons in response to NPY treatment. The downstream signalling pathways coupling NPY-mediated NO synthesis to cell proliferation were identified, through the use of selective pharmacological agonists and antagonists, as soluble guanylate cyclase, cGMP-dependent protein kinase (PKG) and the extracellular signal-regulated kinases (ERK) 1/2. By assessing levels of NPY-mediated ERK 1/2 phosphorylation in response to NOS inhibition, it was found that ERK 1/2 activation was mediated only via NOS/NO mechanisms. This proliferative cGMP-PKG-ERK 1/2 signalling cascade appears to be mediated by intracellularly released NO, while on the other hand, the addition of extracellular NO through the application of NO donors exerted an inhibitory effect on neural precursor cell proliferation. In addition to demonstrating the dual nature of NO, this is the first time that the signalling mechanisms underlying the proliferative effect of NPY on neural precursor cells have been described. Understanding the mechanisms underlying the proliferation of neural precursor cells will ultimately be beneficial by allowing the development of novel therapeutic interventions for promoting hippocampal neurogenesis.To analyse the role of NO in the NPY-mediated neuroproliferation of hippocampal cells in three-dimensional (3D) cultures, Laponite, a novel synthetic silica hydrogel, was used. Culture medium-based Laponite hydrogels were developed before cell viability within the hydrogels were assessed by culturing hippocampal monolayers under gel cover. Hydrogel cover, however, resulted in cell behaviour reminiscent of preservation/fixation as monolayers showed no spatial or morphological changes over time, with one possible explanation being the high gel osmolarity. Although attempts at cell seeding showed more positive results, with cells adhering to a low heavy metal content variation of the hydrogel, determination of cell viability remained a problem due to prominent dye-gel binding. Although the rheological properties of Laponite make its use attractive, the biocompatibility of the hydrogels with hippocampal cells still require further optimisation if they are to be used as cell culture matrices
City, Amenities, and Welfare
No full textThis chapter reviews the mechanisms through which amenities alter patterns of mobility and spatial distribution of population, and summarizes the role of amenities in urban development and on the inequality of labor welfare. The theoretical frameworks in the literature have gradually relaxed the assumption of frictionless spatial equilibrium, and papers can be categorized based on the endogeneity or exogeneity of amenities and the spatial scale of the research. A simple benchmark model and its extensions are used to illustrate how changes in amenities affect endogenous variables such as wages and rents, and drive the spatial sorting of labor. In this process, the endogenous amenities themselves are also subject to changes in the structure of the local labor force and the size of the regional population. Empirical evidence indicates that high levels of endogenous amenity can enhance the overall welfare of labor, but, under different conditions, they may amplify or diminish the inequality of welfare among heterogeneous labor groups, leading to uncertain changes in overall welfare that need to be assessed on a case-by-case basis. Therefore, amenities are a powerful tool for the government to regulate disparities in labor welfare. Additionally, the presence of amenities is a key factor leading to an inefficient spatial sorting of labor, which can be improved upon through specific policies
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