44,175 research outputs found
NLO Leptoquark Production and Decay: The Narrow-Width Approximation and Beyond
We study the leptoquark model of Buchm\"uller, R\"uckl and Wyler, focusing on
a particular type of scalar () and vector () leptoquark. The primary
aim is to perform the calculations for leptoquark production and decay at
next-to-leading order (NLO) to establish the importance of the NLO
contributions and, in particular, to determine how effective the
narrow-width-approximation (NWA) is at NLO. For both the scalar and vector
leptoquarks it is found that the NLO contributions are large, with the larger
corrections occurring for the case vector leptoquarks. For the scalar
leptoquark it is found that the NWA provides a good approximation for
determining the resonant peak, however the NWA is not as effective for the
vector leptoquark. For both the scalar and vector leptoquarks there are large
contributions away from the resonant peak, which are missing from the NWA
results, and these make a significant difference to the total cross-section.Comment: 22 pages, 17 figure
CO adsorption on (111) and (100) surfaces of the Pt sub 3 Ti alloy. Evidence for parallel binding and strong activation of CO
The CO adsorption on a 40 atom cluster model of the (111) surface and a 36 atom cluster model of the (100) surface of the Pt3Ti alloy was studied. Parallel binding to high coordinate sites associated with Ti and low CO bond scission barriers are predicted for both surfaces. The binding of CO to Pt sites occurs in an upright orientation. These orientations are a consequence of the nature of the CO pi donation interactions with the surface. On the Ti sites the orbitals donate to the nearly empty Ti 3d band and the antibonding counterpart orbitals are empty. On the Pt sites, however, they are in the filled Pt 5d region of the alloy band, which causes CO to bond in a vertical orientation by 5 delta donation from the carbon end
Kelly Betting Can Be Too Conservative
Kelly betting is a prescription for optimal resource allocation among a set
of gambles which are typically repeated in an independent and identically
distributed manner. In this setting, there is a large body of literature which
includes arguments that the theory often leads to bets which are "too
aggressive" with respect to various risk metrics. To remedy this problem, many
papers include prescriptions for scaling down the bet size. Such schemes are
referred to as Fractional Kelly Betting. In this paper, we take the opposite
tack. That is, we show that in many cases, the theoretical Kelly-based results
may lead to bets which are "too conservative" rather than too aggressive. To
make this argument, we consider a random vector X with its assumed probability
distribution and draw m samples to obtain an empirically-derived counterpart
Xhat. Subsequently, we derive and compare the resulting Kelly bets for both X
and Xhat with consideration of sample size m as part of the analysis. This
leads to identification of many cases which have the following salient feature:
The resulting bet size using the true theoretical distribution for X is much
smaller than that for Xhat. If instead the bet is based on empirical data,
"golden" opportunities are identified which are essentially rejected when the
purely theoretical model is used. To formalize these ideas, we provide a result
which we call the Restricted Betting Theorem. An extreme case of the theorem is
obtained when X has unbounded support. In this situation, using X, the Kelly
theory can lead to no betting at all.Comment: Accepted in 2016 IEEE 55th Conference on Decision and Control (CDC
Sensitivity of the photo-physical properties of organometallic complexes to small chemical changes
We investigate an effective model Hamiltonian for organometallic complexes
that are widely used in optoelectronic devices. The two most important
parameters in the model are , the effective exchange interaction between the
and orbitals of the ligands, and , the renormalized
energy gap between the highest occupied orbitals on the metal and on the
ligand. We find that the degree of metal-to-ligand charge transfer (MLCT)
character of the lowest triplet state is strongly dependent on the ratio
. is purely a property of the complex and can be
changed significantly by even small variations in the complex's chemistry, such
as replacing substituents on the ligands. We find that that small changes in
can cause large changes in the properties of the complex,
including the lifetime of the triplet state and the probability of injected
charges (electrons and holes) forming triplet excitations. These results give
some insight into the observed large changes in the photophysical properties of
organometallic complexes caused by small changes in the ligands.Comment: Accepted for publication in J. Chem. Phys. 14 pages, 9 figures,
Supplementary Info: 15 pages, 17 figure
Increasing levels of the endocannabinoid 2-AG is neuroprotective in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine mouse model of Parkinson's disease
Date of Acceptance: 28/07/2015 The authors are grateful to the staff of the Medical Research Facility for their help with the animal care. This work was supported by the NHS Endowment fund 09/03 and the Wellcome Trust (WT080782MF). We thank Merck & Co. Inc., Rathway NJ, USA for the supply of DFU.Peer reviewedPublisher PD
Effects of deleting cannabinoid receptor-2 on mechanical and material properties of cortical and trabecular bone
Acknowledgements We thank Dr J.S. Gregory for assistance with Image J and Mr K. Mackenzie for assistance with Micro-CT analysis. Funding ABK was funded by a University of Aberdeen, Institute of Medical Sciences studentship and the Overseas Research Students Awards Scheme.Peer reviewedPublisher PD
Mechanical and material properties of cortical and trabecular bone from cannabinoid receptor-1-null (Cnr1-/-) mice
Funding ABK was funded by a studentship from the University of Aberdeen, Institute of Medical Sciences, and the Overseas Research Students Awards Scheme Acknowledgments We are grateful to Dr J.S. Gregory for assistance with Image J and Mr K. Mackenzie for assistance with Micro-CT analysis.Peer reviewedPostprin
Comparison of research framing preferences and information use of state legislators and advocates involved in cancer control, United States, 2012–2013
INTRODUCTION: Evidence-based policy plays an important role in prevention of cancer and other chronic diseases. The needs of actors involved in policy decision-making should inform knowledge translation strategies. This study examines the differences between state legislators and advocates in how they seek and use information and what their preferences are for how research information is framed. METHODS: We conducted a cross-sectional comparison of survey responses by US advocates (n = 77) and state legislators (n = 265) working on issues related to cancer control. RESULTS: Advocates differed significantly from legislators on all demographic characteristics. Advocates reported seeking and using information more frequently than legislators, though legislators used legislative research bureaus more often (0.45 point difference, P = .004). Both legislators and advocates prioritized the presentation and timeliness of research information similarly but reported different preferences for source (information bias, information relevance, delivery of information by trusted person) of research information. Several differences between advocates and legislators were modified by participant age. CONCLUSION: Our study provides insights for development of knowledge translation strategies to enhance evidence-based policy making for cancer control that are tailored to state-level legislators and advocates. Additional research efforts should evaluate the effectiveness of such knowledge translation strategies, particularly among advocates
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