132,784 research outputs found
Quantum state protection using all-optical feedback
Get PDFAn all-optical feedback scheme in which the output of a cavity mode is used
to influence the dynamics of another cavity mode is considered. We show that
under ideal conditions, perfect preservation against decoherence of a generic
quantum state of the source mode can be achieved.Comment: 10 pages, 4 figures, to appear in the Dan Walls Memorial Volume,
edited by H. Carmichael, R. Glauber, and M. Scully, to be published by
Springe
Professional sports economics and competitive balance. Limits of a very used approach: "noll-Scully measure of Competitive Balance"
Get PDFL'équilibre compétitif constitue un concept fondateur de l'économie du sport professionnel. Il postule un lien central entre l'incertitude du résultat et la demande du public. La mesure la plus utilisée dans la littérature est l'approche « Noll-Scully ». Elle confronte l'écart dans le classement des équipes entre le réel observé et le théorique idéal compte tenu du nombre de matchs. L'objet de cette contribution est de discuter la pertinence de l'approche. Après un aperçu de la littérature, la 2e partie aborde les points d'achoppement que sont son objectif (intégrer l'influence du nombre de matchs) et sa formulation (incorporer une valeur théorique idéale). L'article oriente ensuite la discussion sur une mesure alternative susceptible d'éviter les lacunes de l'approche « Noll-Scully »
Marginal revenue product and salaries: Moneyball redux
Get PDFScully (1974) used a two equation regression model to estimate a baseball player’s salary to compare to the actual salary the player earned in order to determine if a player is paid his net marginal revenue product. We replicate the spirit of that paper, but introduce several useful innovations to estimate net marginal revenue products for a large sample of free-agent baseball players. Our results suggest that the highest paid free agents are overpaid, while all other free agents are underpaid or paid appropriately. We found no evidence for the notion that some clubs may be more adept at finding “bargain” free agents.net marginal revenue product; free agents; baseball
Searching for traces of Planck-scale physics with high energy neutrinos
No full textHigh-energy cosmic neutrino observations provide a sensitive test of Lorentz invariance violation (LIV), which may be a consequence of quantum gravity theories. We consider a class of nonrenormalizable, Lorentz invariance violating operators that arise in an effective field theory (EFT) description of Lorentz invariance violation in the neutrino sector inspired by Planck-scale physics and quantum gravity models. We assume a conservative generic scenario for the redshift distribution of extragalactic neutrino sources and employ Monte Carlo techniques to describe superluminal neutrino propagation, treating kinematically allowed energy losses of superluminal neutrinos caused by both vacuum pair emission (VPE) and neutrino splitting. We consider EFTs with both nonrenormalizable CPT -odd and nonrenormalizable CPT -even operator dominance. We then compare the spectra derived using our Monte Carlo calculations in both cases with the spectrum observed by IceCube in order to determine the implications of our results regarding Planck-scale physics. We find that if the dropoff in the neutrino flux above similar to 2 PeV is caused by Planck-scale physics, rather than by a limiting energy in the source emission, a potentially significant pileup effect would be produced just below the dropoff energy in the case of CPT -even operator dominance. However, such a clear dropoff effect would not be observed if the CPT -odd, CPT -violating term dominates
MeSH term explosion and author rank improve expert recommendations
Get PDFInformation 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
Get PDFThe 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
Polyphenols, oral health and disease: A review
No full textObjective: Polyphenols (PPs) are reactive metabolites abundant in plant-derived foods, particularly fruits, seeds and leaves. In the tissues of the digestive tract, particularly the oral mucosa, active PPs reach the highest concentration. Although excessively high and monotonic intake may be toxic (such an effect is countered by salivary proline-rich proteins), PPs exert preventive activity against infectious and degenerative diseases and may also help prevent oral diseases, via mechanisms like antioxidant activity and neutralisation/modulation of human/bacterial/viral proteins/enzymes. This review seeks to investigate the preventive PP activity against oral diseases. Methods: Studies published during the last 15 years were searched using MEDLINE, PUBMED, EMBASE. The quality of evidence was rated using the three-point scale used by the US Preventive Services Task Force to assess the merits of preventive measures. Results: Consistent, well-designed, epidemiological, animal and in vitro studies directly and indirectly support the preventive PP effect against oral cancer with good evidence. Consistent studies showing that PPs inactivate periodontal pathogens and increase antioxidant capacity of oral fluids, suggest a preventive effect against periodontal disease with fair evidence. Animal and in vitro studies showing that PPs decrease mutans streptococci virulence and dental plaque accumulation, suggest a preventive effect against dental caries with fair evidence. Meta-analysing clinical trials on subjects refraining from oral hygiene, PP-containing mouthrinses decrease mutans streptococci level by almost 50% and Plaque Index score. Conclusions: Regular and frequent PP intake may help protect against oral cancer, while human studies are needed to confirm the promising preventive activity against periodontal disease and caries. (D 2009 Elsevier Ltd. All rights reserved
Motors and Impossible Firing Patterns in the Parallel Chip-Firing Game
No full textThe parallel chip-firing game is an automaton on graphs in which vertices “fire” chips to their neighbors. This simple model contains much emergent complexity and has many connections to different areas of mathematics. In this work, we study firing sequences, which describe each vertex's interaction with its neighbors in this game. First, we introduce the concepts of motors and motorized games. Motors both generalize the game and allow us to isolate local behavior of the (ordinary) game. We study the effects of motors connected to a tree and show that motorized games can be transformed into ordinary games if the motor's firing sequence occurs in some ordinary game. Then, we completely characterize the periodic firing sequences that can occur in an ordinary game, which have a surprisingly simple combinatorial description
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
Get PDFBoth 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.
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