6,643 research outputs found
Estimating an NBA player's impact on his team's chances of winning
Traditional NBA player evaluation metrics are based on scoring differential
or some pace-adjusted linear combination of box score statistics like points,
rebounds, assists, etc. These measures treat performances with the outcome of
the game still in question (e.g. tie score with five minutes left) in exactly
the same way as they treat performances with the outcome virtually decided
(e.g. when one team leads by 30 points with one minute left). Because they
ignore the context in which players perform, these measures can result in
misleading estimates of how players help their teams win. We instead use a win
probability framework for evaluating the impact NBA players have on their
teams' chances of winning. We propose a Bayesian linear regression model to
estimate an individual player's impact, after controlling for the other players
on the court. We introduce several posterior summaries to derive rank-orderings
of players within their team and across the league. This allows us to identify
highly paid players with low impact relative to their teammates, as well as
players whose high impact is not captured by existing metrics.Comment: To appear in the Journal of Quantitative Analysis of Spor
A Separate Higgs?
We investigate the possibility of a multi-Higgs doublet model where the
lightest neutral Higgs boson () decouples from the fermion sector. We are
partially motivated by the four events with
\,GeV recently observed by the L3 collaboration,
which could be a signal for .
Collider signatures for the additional physical Higgs bosons present in such
models are discussed.Comment: 8 pages (plus 2 figures, available by request), latex,
ANL-HEP-PR-92-10
Prospects for Direct CP Violaton in Exclusive and Inclusive Charmless B decays
Within the Standard Model, CP rate asymmetries for could
reach 10%. With strong final state phases, they could go up to 20--30%, even
for mode which would have opposite sign. We can account for
, and rate data with new physics enhanced
color dipole coupling and destructive interference. Asymmetries could reach
40--60% for and modes and are all of the same sign. We are
unable to account for rate. Our inclusive study supports our
exclusive results.Comment: Minor changes, correct a small bug in Fig. 1(b). Version to appear in
Phys. Rev. Let
Optimizing enzymatic catalysts for rapid turnover of substrates with low enzyme sequestration
Enzymes are central to both metabolism and information processing in cells. In both cases, an enzyme’s ability to accelerate a reaction without being consumed in the reaction is crucial. Nevertheless, enzymes are transiently sequestered when they bind to their substrates; this sequestration limits activity and potentially compromises information processing and signal transduction. In this article, we analyse the mechanism of enzyme–substrate catalysis from the perspective of minimizing the load on the enzymes through sequestration, while maintaining at least a minimum reaction flux. In particular, we ask: which binding free energies of the enzyme–substrate and enzyme–product reaction intermediates minimize the fraction of enzymes sequestered in complexes, while sustaining a certain minimal flux? Under reasonable biophysical assumptions, we find that the optimal design will saturate the bound on the minimal flux and reflects a basic trade-off in catalytic operation. If both binding free energies are too high, there is low sequestration, but the effective progress of the reaction is hampered. If both binding free energies are too low, there is high sequestration, and the reaction flux may also be suppressed in extreme cases. The optimal binding free energies are therefore neither too high nor too low, but in fact moderate. Moreover, the optimal difference in substrate and product binding free energies, which contributes to the thermodynamic driving force of the reaction, is in general strongly constrained by the intrinsic free-energy difference between products and reactants. Both the strategies of using a negative binding free-energy difference to drive the catalyst-bound reaction forward and of using a positive binding free-energy difference to enhance detachment of the product are limited in their efficacy
Left-Right Symmetry and Supersymmetric Unification
The existence of an SU(3) X SU(2)_L X SU(2)_R X U(1) gauge symmetry with g_L
= g_R at the TeV energy scale is shown to be consistent with supersymmetric
SO(10) grand unification at around 1O^{16} GeV if certain new particles are
assumed. The additional imposition of a discrete Z_2 symmetry leads to a
generalized definition of R parity as well as highly suppressed Majorana
neutrino masses. Another model based on SO(10) X SO(10) is also discussed.Comment: 11 pages, 2 figures not included, UCRHEP-T124, Apr 199
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The effect of inclination and stand-off on the dynamic response of beams impacted by slugs of a granular material
The dynamic response of end-clamped sandwich and monolithic beams to impact by highvelocity
tungsten carbide (WC) particle columns (slugs) has been measured with the aim of
developing an understanding of the interaction of ejecta from a shallow-buried explosion with
structures. The monolithic beams were made from stainless steel, while the sandwich beams
of equal areal mass comprised stainless steel face sheets and an aluminium honeycomb core.
High-speed imaging was used to measure the transient transverse deflection of the beams, to
record the dynamic modes of deformation, and to observe the flow of the WC particles upon
impact. The experiments show that sandwich beams deflect less than the monolithic beams
both in normal and inclined impact situations. Moreover, the deflections of all beams in the
inclined orientation were less than their respective deflections in the normal orientation at the
same slug velocity. Intriguingly, the ratio of the deflection of the sandwich to monolithic
beams remains approximately constant with increasing slug velocity for inclined impact but
increases for normal impact; i.e. inclined sandwich beams retain their advantage over
monolithic beams with increasing slug velocity. Dynamic force measurements reveal that (i)
the momentum transferred from the impacting slug to both monolithic and sandwich beams is
the same, and (ii) the interaction between the impacting particles and the dynamic
deformation of the inclined monolithic and sandwich beams results in a momentum transfer
into these beams that is equal to or greater than the momentum of the slug. These
experimental findings demonstrate that contrary to intuition and widespread belief, the
performance enhancement obtained from employing beam inclination is not due to a
reduction in transferred momentum. Finally, we show that increasing the stand-off distance
decreases beam deflections. This is because the slugs lengthen as they traverse towards their
target and thus the duration of loading is extended with increasing stand-off. However,
combining increased stand-off with sandwich construction does not yield the synergistic
benefits of sandwich construction combined with beam inclination.The work was supported by the Office of Naval Research Grant N00014-09-1-0573 (Program
manager, Dr. David Shifler) and the Defense Advanced Projects Agency under grant number
W91CRB-11-1-0005 (Program manager, Dr. J. Goldwasser).This is the accepted manuscript. The final version is available from Elsevier at http://www.sciencedirect.com/science/article/pii/S0020768314004466
Spin Effects in the Local Density of States of GaAs
We present spin-resolved measurements of the local density of states in Si
doped GaAs. Both spin components exhibit strong mesoscopic fluctuations. In the
magnetic quantum limit, the main features of the spin-up and spin-down
components of the local density of states are found to be identical apart from
Zeeman splitting. Based on this observation, we introduce a mesoscopic method
to measure the -factor in a material where macroscopic methods are severely
restricted by disorder. Differences between the spin-up and spin-down
components are discussed in terms of spin relaxation due to spin-orbit
coupling.Comment: 4 pages and 5 figure
CP Violation in a Multi-Higgs Doublet Model
We study CP violation in a multi-Higgs doublet model based on a horizontal symmetry. We consider two mechanisms for CP violation in this
model: a) CP violation due to complex Yukawa couplings; and b) CP violation due
to scalar-pseudoscalar mixings. We find that the predictions for
, CP violation in B decays and the electric dipole moments
of neutron and electron are different between these two mechanisms. These
predictions are also dramatically different from the minimal Standard Model
predictions.Comment: 17 pages + one figure, Revtex. Talk presented by Deshpande at the
Conference WHEPP-3, December 199
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