130,411 research outputs found
Trimpi Perturbations from Large Ionisation Enhancement Patches
No full textA number of increasingly sophisticated and realistic models have been developed in order to investigate the interaction between sub-ionospherically propagating VLF waves and regions of enhanced electron density in the D-region caused by lightning induced electron precipitation (LIEs). These LIEs can result in phase and amplitude perturbations on received VLF signals that are referred to as Trimpis. It is important, for comparison with experimentally observed Trimpi effects, that the spatial extent of the D-region electron density perturbation is modeled accurately. Here, it is argued that most previous modeling has used patch sizes that are typically up to 100 km in both latitudinal and longitudinal extent, which are generally smaller than those that actually occur for real lightning induced electron precipitation events. It would also appear that maximum ?Ne values assumed have often been too large and patches have been incorrectly modeled as circular rather than elliptical in horizontal extent. Consequently, in the present work, Trimpi perturbations are determined for LIEs with smaller maximum ?Ne, larger spatial extent and elliptical shape. Calculations of VLF Trimpis have been made as a function of the horizontal coordinates of the LIE centre, over the whole rectangular corridor linking transmitter and receiver. The Trimpi modelling program is fully 3D, and takes account of modal mixing at the LIE. The underlying theory assumes weak Born scattering, but the code calculates a non-Born skin depth attenuation function for the LIE in question. The LIE is modelled as an electron density enhancement with a Gaussian profile in all coordinates. Results for a large elliptical LIE ~ 200 x 600 kms show that significant Trimpis, ~-0.4dB in amplitude and ~+4 degrees in phase are predicted, using modest maximum ?Ne values ~ 1.5 el/cc. Such an electron density enhancement is well within the range that would be expected to result from experimentally observed fluxes of electron precipitation following wave particle interactions with whistler-mode waves. This shows the continued viability of the original explanation of whistler-induced electron precipitation as the mechanism for the “Classical Trimpi”
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
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
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Relationship between daily and day-to-day glycemic variability and increased oxidative stress in type 2 diabetes
No full textAbstractAimsTo determine the association of daily and day-to-day glucose variability with oxidative stress.MethodsThis was a cross-sectional analysis of 68 patients with type 2 diabetes mellitus (T2DM) over 72h of continuous glucose monitoring. Fasting plasma glucose (FPG) and hemoglobin A1c (HbA1c) were measured before breakfast on day 1. Glucose variability, mean glucose level (MGL), mean amplitude of glycemic excursions (MAGE), mean of daily differences (MODD) in glucose levels and area under the postprandial plasma glucose curve (AUCPP) were measured on days 2 and 3. Plasma oxidant capacity against N,N-diethylparaphenylenediamine was measured with the diacron-reactive oxygen metabolites (d-ROMs) test on day 1.ResultsOverall, 66.2% males with the mean age of 63.2±12.6years, diabetes duration of 12.9±10.4years, and HbA1c level of 8.1±1.6% (65±17mmol/mol) were included. MGL (r=0.330), HbA1c (r=0.326), MAGE (r=0.565), MODD (r=0.488), and AUCPP (r=0.254) exhibited significant correlations with d-ROMs and not FPG; these correlations remained significant after adjustment for clinical factors (sex, age, duration of diabetes, smoking habit, insulin use, statin use, angiotensin II receptor blocker use, BMI, LDL-C, HDL-C, TG, eGFR, and systolic blood pressure) (R2=0.268, R2=0.268, R2=0.417, R2=0.314, and R2=0.347, respectively). MAGE was significantly correlated with MODD (r=0.708) and MAGE and MODD were independently correlated with d-ROMs by multivariate analysis.ConclusionsTherefore, oxidative stress is associated with daily and day-to-day glucose variability in patients with T2DM
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
Scholarly Communication and Publishing Lunch and Learn Talk #11: The ULS Open Access Author Fee Fund
No full textAt the May 2014 talk, you will learn about the ULS Open Access Author Fee Fund--what it is, why we do it, how it works, and how the program is going so far
Darstellungen regulärer Bäume und wilde Unterkategorien von verallgemeinerten Kronecker-Köchern
No full textLet , be an algebraically closed field of characteristic and be a -elementary abelian group of rank .
It is well known that the category of finite dimensional -modules \modd kE_r is of wild type, whenever or and .
Therefore subclasses with more restrictive properties have been studied. In 2008 Carlson, Friedlander and Suslin introduced the subclass of modules
of constant rank and modules with even more restrictive properties, called equal images property and equal kernels property.
In her PhD thesis Worch uses a faithful exact functor \fF_{n} \colon \modd B(n,r) \to \modd kE_r from the module category of the generalized Beilinson algebra on vertices
into the module category of the group algebra to define the equal images and equal kernels property in the framework of the Beilinson algebra.
We follow this approach in the special case and , i.e. is the generalized Kronecker \cK_r = k\Gamma_r algebra with arrows.
Inspired by recent work of Carlson, Friedlander and Pevtsova concerning modules , we introduce the notions of modules with constant -radical rank and modules with constant
-socle rank for \cK_r and .
We study subcategories given by modules with the equal -radical property and the equal -socle property.
Utilizing the Simplification method due to Ringel, we prove that these subcategories in \modd \cK_r are of wild type. Then we use the functor \fF_{2} \colon \modd \cK_r \to \modd kE_r to transfer our results to \modd kE_r.
This thesis is also motivated by the aim to give new insights into the wild category \modd \cK_r
The R&D Tax Incentives
No full textThis article sets out some background information and reflections of the author on the R&D tax incentive schemes included in the Common Corporate Tax Base (CCTB) Proposal. In particular the author analyzes the stimulus to private R&D through ad hoc tax incentives included in the CCTB Proposal and dives into the actual provisions included in the Proposal highlighting the most relevant issues connected with their design and interpretation. Moreover, the author explores the interaction between the CCTB Proposal and the granting by Member States of domestic R&D tax incentives
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