130,864 research outputs found
Search for excited electrons and muons in √s=8 TeV proton–proton collisions with the ATLAS detector
No full textThe ATLAS detector at the Large Hadron Collider is used to search for excited electrons and excited muons in the channel pp → ℓℓ* → ℓℓγ, assuming that excited leptons are produced via contact interactions. The analysis is based on 13 fb[superscript −1] of pp collisions at a centre-of-mass energy of 8 TeV. No evidence for excited leptons is found, and a limit is set at the 95% credibility level on the cross section times branching ratio as a function of the excited-lepton mass m[subscript ℓ*]. For m[subscript ℓ*] ≥ 0.8 TeV, the respective upper limits on σB(ℓ* → ℓγ) are 0.75 and 0.90 fb for the e* and μ* searches. Limits on σB are converted into lower bounds on the compositeness scale Λ. In the special case where Λ = m[subscript ℓ*], excited-electron and excited-muon masses below 2.2 TeV are excluded.United States. Dept. of EnergyNational Science Foundation (U.S.)Brookhaven National Laborator
Hydrogen Sulfide as a Toxic Product in the Small-Large Intestine Axis and its Role in IBD Development
No full textThe small-large intestine axis in hydrogen sulfide accumulation and testing of sulfate and lactate in the gut-gut axis of the intestinal environment has not been well described. Sulfate reducing bacteria (SRB) of the Desulfovibrio genus reduce sulfate to hydrogen sulfide and can be involved in ulcerative colitis development. The background of the research was to find correlations between hydrogen sulfide production under the effect of an electron acceptor (sulfate) and donor (lactate) at different concentrations and Desulfovibrio piger Vib-7 growth, as well as their dissimilatory sulfate reduction in the intestinal small-large intestinal environment. METHODS: Microbiological, biochemical, and biophysical methods, and statistical processing of the results (principal component and cross-correlation analyses) were used. RESULTS: D. piger Vib-7 showed increased intensity of bacterial growth and hydrogen sulfide production under the following concentrations of sulfate and lactate: 17.4 mM and 35.6 mM, respectively. The study showed in what kind of intestinal environment D. piger Vib-7 grows at the highest level and produces the highest amount of hydrogen sulfide. CONCLUSIONS: The optimum intestinal environment of D. piger Vib-7 can serve as a good indicator of the occurrence of inflammatory bowel diseases; meaning that these findings can be broadly used in medicine practice dealing with the monitoring and diagnosis of intestinal ailments
Does selection for gamete dispersal and capture lead to a sex difference in clump water holding capacity?
No full textFor methods please see:Moore, J. D., L. M. Kollar, and D. N. McLetchie. Does selection for gamete dispersal and capture
lead to a sex difference in clump water- holding
capacity? American Journal of Botany. in press.</div
Sampling Delay and Backlash in Balancing Systems
No full textA mechanical model of a digital balancing system is constructed and its stability analysis is presented. This model considers experimental problems like backlash and sampling delay. The conditions of existence of stable stationary and periodic solutions are determined for the case of the system without delay. Phase diagrams and bifurcation diagrams are revealed after simulations and bifurcation analysis. Adding sampling delay to the system, the stability conditions are changed and above a critical value of the delay, the balancing is impossible. The stability conditions and the stability chart are determined again and the critical sampling delay is calculated versus the parameters describing the system
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
Vibration of Bundled Conductors Following Ice Shedding
No full textThe dynamic behavior of bundled conductors following ice shedding from one subconductor is examined numerically using the finite-element method. An existing model of ice shedding from a single conductor is improved by developing a model of spacers which connect subconductors in the span. The resulting system makes it possible to simulate vibrations following ice shedding from one span of an overhead transmission line with twin, triple, or quad bundles. Vibration characteristics are evaluated as the following parameters are varied: thickness of shed ice, distance between adjacent spacers, and number of subconductors in the bundle. Simulation results will provide information on how the amplitude of vibration and the transient dynamic forces change with the application of spacers. The maximum jump height of the ice-shedding cable, the maximum drop of the loaded cable, and the maximum cable tension are approximated as power functions of ice thickness and the distance between adjacent spacers
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
Toward a script theory of guidance in computer-supported collaborative learning
No full textThis article presents an outline of a script theory of guidance for computer-supported collaborative learning (CSCL). With its four types of components of internal and external scripts (play, scene, role, and scriptlet) and seven principles, this theory addresses the question how CSCL practices are shaped by dynamically re-configured internal collaboration scripts of the participating learners. Furthermore, it explains how internal collaboration scripts develop through participation in CSCL practices. It emphasizes the importance of active application of subject matter knowledge in CSCL practices, and it prioritizes transactive over non-transactive forms of knowledge application in order to facilitate learning. Further, the theory explains how external collaboration scripts modify CSCL practices and how they influence the development of internal collaboration scripts. The principles specify an optimal scaffolding level for external collaboration scripts and allow for the formulation of hypotheses about the fading of external collaboration scripts. Finally, the article points towards conceptual challenges and future research questions
"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.
Posible declinación poblacional de la mariposa Papilio polyxenes americus Kollar (Lepidoptera: Papilionidae) en el valle intra-andino de Mérida, Venezuela
No full textOrellana A, Erazo M. 2002. Possible population decline of the
swallowtail Papilio polyxenes americus Kollar (Lepidoptera:
Papilionidae) in the intra-Andean valley of Mérida, Venezuela.
Entomotropica 17(2):189-190. Since the second half of the 90's, the
swallowtail butterfly, Papilio polyxenes americus Kollar, 1859, a
formerly common species, has become scarce or may even be disappearing
from the Chama river basin of Andean Mérida, Venezuela. No
concrete explanations are given for the fact, but it is presumed that
it may be linked to human activities, especially the use of pesticides
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