885 research outputs found
Chimney Foundation on Drilled Piers
This paper describes the design and compares predicted performance to actual responses of a drilled pier foundation supporting a 305m high chimney. The purpose was to evaluate laboratory and empirical side friction and end bearing criteria used in the pier design. Based on results of a subsurface exploration program, and consideration of vibration effects on nearby structures, a foundation system was designed consisting of 38 drilled piers capped with a concrete mat. The piers had an average diameter of 1.37m in soil and 1.22m in rock. The average length of pier was 15.63m including a rock socket 2.44m deep. Each pier was designed to support a maximum compressional load of 1,362 tons. The side friction and end bearing capacity was analyzed from data accumulated under construction and service conditions. A comparison of this analysis with criteria suggested by others indicated compliance with accepted design standards
Low-Dimensional Long-Range Topological Charge Structure in the QCD Vacuum
While sign-coherent 4-dimensional structures cannot dominate topological
charge fluctuations in the QCD vacuum at all scales due to reflection
positivity, it is possible that enhanced coherence exists over extended
space-time regions of lower dimension. Using the overlap Dirac operator to
calculate topological charge density, we present evidence for such structure in
pure-glue SU(3) lattice gauge theory. It is found that a typical equilibrium
configuration is dominated by two oppositely-charged sign-coherent connected
structures (``sheets'') covering about 80% of space-time. Each sheet is built
from elementary 3-d cubes connected through 2-d faces, and approximates a
low-dimensional curved manifold (or possibly a fractal structure) embedded in
the 4-d space. At the heart of the sheet is a ``skeleton'' formed by about 18%
of the most intense space-time points organized into a global long-range
structure, involving connected parts spreading over maximal possible distances.
We find that the skeleton is locally 1-dimensional and propose that its
geometrical properties might be relevant for understanding the possible role of
topological charge fluctuations in the physics of chiral symmetry breaking.Comment: 4 pages RevTeX, 4 figures; v2: 6 pages, 5 figures, more explanations
provided, figure and references added, published versio
Quantum Dynamics of a Hydrogen Molecule Confined in a Cylindrical Potential
We study the coupled rotation-vibration levels of a hydrogen molecule in a
confining potential with cylindrical symmetry. We include the coupling between
rotations and translations and show how this interaction is essential to obtain
the correct degeneracies of the energy level scheme. We applied our formalism
to study the dynamics of H molecules inside a "smooth" carbon nanotube as
a function of tube radius. The results are obtained both by numerical solution
of the ()-component radial Schrodinger equation and by developing an
effective Hamiltonian to describe the splitting of a manifold of states of
fixed angular momentum and number of phonons, . For nanotube radius
smaller than \AA, the confining potential has a parabolic shape
and the results can be understood in terms of a simple toy model. For larger
radius, the potential has the "Mexican hat" shape and therefore the H
molecule is off-centered, yielding radial and tangential translational dynamics
in addition to rotational dynamics of H molecule which we also describe
by a simple model. Finally, we make several predictions for the the neutron
scattering observation of various transitions between these levels.Comment: 36 pages, 8 figures, submitted to Phys. Rev. B on 12 December 200
Measurement of the branching ratio of the decay
From the 2002 data taking with a neutral kaon beam extracted from the
CERN-SPS, the NA48/1 experiment observed 97 candidates with a background contamination of events.
From this sample, the BR() is measured to be
First Observation and Measurement of the Decay K+- -> pi+- e+ e- gamma
Using the full data set of the NA48/2 experiment, the decay K+- -> pi+- e+ e-
gamma is observed for the first time, selecting 120 candidates with 7.3 +- 1.7
estimated background events. With K+- -> pi+- pi0D as normalisation channel,
the branching ratio is determined in a model-independent way to be Br(K+- ->
pi+- e+ e- gamma, m_eegamma > 260 MeV/c^2) = (1.19 +- 0.12_stat +- 0.04_syst) x
10^-8. This measured value and the spectrum of the e+ e- gamma invariant mass
allow a comparison with predictions of Chiral Perturbation Theory.Comment: 13 pages, 3 figures. Accepted for publication in Phys.Lett.
Observation of the rare decay K_S -> pi^0mu^+mu^-
A search for the decay K_S -> pi^0mu^+mu^- has been made by the NA48/1
Collaboration at the CERN SPS accelerator. The data were collected during 2002
with a high-intensity K_S beam. Six events were found with a background
expectation of 0.22^+0.18_-0.11 event. Using a vector matrix element and unit
form factor, the measured branching ratio is B(K_S ->
pi^0mu^+mu^-)=[2.9^+1.5_-1.2(stat)+/-0.2(syst)]x10^{-9}.Comment: 19 pages, 8 figures, 4 tables. To be published in Physics Letters
Empirical parameterization of the K+- -> pi+- pi0 pi0 decay Dalitz plot
As first observed by the NA48/2 experiment at the CERN SPS, the \p0p0
invariant mass (M00) distribution from \kcnn decay shows a cusp-like anomaly
at M00=2m+, where m+ is the charged pion mass. An analysis to extract the pi pi
scattering lengths in the isospin I=0 and I=2 states, a0 and a2, respectively,
has been recently reported. In the present work the Dalitz plot of this decay
is fitted to a new empirical parameterization suitable for practical purposes,
such as Monte Carlo simulations of K+- -> pi+- pi0 pi0 decays.Comment: 9 pages, 3 figures
Overview of the Proton-coupled MCT (SLC16A) Family of Transporters: Characterization, Function and Role in the Transport of the Drug of Abuse γ-Hydroxybutyric Acid
The transport of monocarboxylates, such as lactate and pyruvate, is mediated by the SLC16A family of proton-linked membrane transport proteins known as monocarboxylate transporters (MCTs). Fourteen MCT-related genes have been identified in mammals and of these seven MCTs have been functionally characterized. Despite their sequence homology, only MCT1–4 have been demonstrated to be proton-dependent transporters of monocarboxylic acids. MCT6, MCT8 and MCT10 have been demonstrated to transport diuretics, thyroid hormones and aromatic amino acids, respectively. MCT1–4 vary in their regulation, tissue distribution and substrate/inhibitor specificity with MCT1 being the most extensively characterized isoform. Emerging evidence suggests that in addition to endogenous substrates, MCTs are involved in the transport of pharmaceutical agents, including γ-hydroxybuytrate (GHB), 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase inhibitors (statins), salicylic acid, and bumetanide. MCTs are expressed in a wide range of tissues including the liver, intestine, kidney and brain, and as such they have the potential to impact a number of processes contributing to the disposition of xenobiotic substrates. GHB has been extensively studied as a pharmaceutical substrate of MCTs; the renal clearance of GHB is dose-dependent with saturation of MCT-mediated reabsorption at high doses. Concomitant administration of GHB and l-lactate to rats results in an approximately two-fold increase in GHB renal clearance suggesting that inhibition of MCT1-mediated reabsorption of GHB may be an effective strategy for increasing renal and total GHB elimination in overdose situations. Further studies are required to more clearly define the role of MCTs on drug disposition and the potential for MCT-mediated detoxification strategies in GHB overdose
First observation and branching fraction and decay parameter measurements of the weak radiative decay Xi0 --> Lambda e+e-
The weak radiative decay Xi0 --> Lambda e+e- has been detected for the first
time. We find 412 candidates in the signal region, with an estimated background
of 15 +/- 5 events. We determine the branching fraction B(Xi0 --> Lambda e+e-)
= [7.6 +/- 0.4(stat) +/- 0.4(syst) +/- 0.2(norm)] x 10^{-6}, consistent with an
internal bremsstrahlung process, and the decay asymmetry parameter
alpha_{XiLambdaee} = -0.8 +/- 0.2, consistent with that of Xi0 --> Lambda
gamma. The charge conjugate reaction Xi0_bar --> Lambda_bar e+e- has also been
observed.Comment: 20 pages, 5 figures, 4 tables; revised: 19 pages, 4 figures, 4
tables, after reviewers' comments: 1 figure removed, 1 figure corrected,
minor editorial changes; to be published in Phys. Lett.
Search for direct CP-violation in K+- --> pi+-pi0pi0 decays
A search for direct CP-violation in K+- --> pi+-pi0pi0 decays based on 47.14
million events has been performed by the NA48/2 experiment at the CERN SPS. The
asymmetry in the Dalitz plot linear slopes A_g=(g^+ - g^-)/(g^+ + g^-) is
measured to be A_g=(1.8 +- 2.6).10^{-4}. The design of the experiment and the
method of analysis provide good control of instrumental charge asymmetries in
this measurement. The precision of the result is limited by statistics and is
almost one order of magnitude better than that of previous measurements by
other experiments.Comment: 14 page
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