3,034 research outputs found
Database Marketing: A Potent Tool for Hospitality Marketers
Nearly every industry, including hospitality, has adopted database marketing techniques. Why have they become so popular and what advantages do they offer for hospitality companies? The authors examine these issues
Sum Rules for Magnetic Moments and Polarizabilities in QED and Chiral Effective-Field Theory
We elaborate on a recently proposed extension of the Gerasimov-Drell-Hearn
(GDH) sum rule which is achieved by taking derivatives with respect to the
anomalous magnetic moment. The new sum rule features a {\it linear} relation
between the anomalous magnetic moment and the dispersion integral over a
cross-section quantity. We find some analogy of the linearized form of the GDH
sum rule with the `sideways dispersion relations'. As an example, we apply the
linear sum rule to reproduce the famous Schwinger's correction to the magnetic
moment in QED from a tree-level cross-section calculation and outline the
procedure for computing the two-loop correction from a one-loop cross-section
calculation. The polarizabilities of the electron in QED are considered as well
by using the other forward-Compton-scattering sum rules. We also employ the sum
rules to study the magnetic moment and polarizabilities of the nucleon in a
relativistic chiral EFT framework. In particular we investigate the chiral
extrapolation of these quantities.Comment: 24 pages, 7 figures; several additions, published versio
Double radiative pion capture on hydrogen and deuterium and the nucleon's pion cloud
We report measurements of double radiative capture in pionic hydrogen and
pionic deuterium. The measurements were performed with the RMC spectrometer at
the TRIUMF cyclotron by recording photon pairs from pion stops in liquid
hydrogen and deuterium targets. We obtained absolute branching ratios of for hydrogen and for deuterium, and
relative branching ratios of double radiative capture to single radiative
capture of for hydrogen
and for
deuterium. For hydrogen, the measured branching ratio and photon energy-angle
distributions are in fair agreement with a reaction mechanism involving the
annihilation of the incident on the cloud of the target proton.
For deuterium, the measured branching ratio and energy-angle distributions are
qualitatively consistent with simple arguments for the expected role of the
spectator neutron. A comparison between our hydrogen and deuterium data and
earlier beryllium and carbon data reveals substantial changes in the relative
branching ratios and the energy-angle distributions and is in agreement with
the expected evolution of the reaction dynamics from an annihilation process in
S-state capture to a bremsstrahlung process in P-state capture. Lastly, we
comment on the relevance of the double radiative process to the investigation
of the charged pion polarizability and the in-medium pion field.Comment: 44 pages, 7 tables, 13 figures, submitted to Phys. Rev.
Asymptomatic Deep Venous Thrombosis is Associated with a Low Risk of Post-thrombotic Syndrome
AbstractPost-thrombotic syndrome (PTS) is a well-recognized condition that develops after symptomatic deep venous thrombosis, but the clinical significance and late complications of asymptomatic deep venous thrombosis (ADVT) are unclear.ObjectiveTo determine whether ADVT following minor surgery affects venous function and contributes to the later development of PTS.Patients/methodsThe study included 83 patients operated on for Achilles tendon rupture; 38 patients with postoperative ADVT and 45 patients without (control group). The follow-up examinations five years after the operation comprised computerised strain-gauge plethysmography, colour duplex ultrasonography, clinical scoring of venous disease, and quality of life (QOL).ResultsVillalta scores, CEAP classification and QOL did not differ between groups. PTS (=Villalta score≥5) was found in three ADVT patients (8%) and in two controls (4%). Ultrasonography revealed post-thrombotic changes in 55% of ADVT patients and in none of the controls. Deep venous reflux occurred in 22 ADVT patients and in three controls (P<0.001). There was no difference between groups in plethysmographic variables, demonstrating that the ultrasonographic abnormalities were of negligible haemodynamic significance.ConclusionsPTS is not a common sequel to ADVT after minor surgery. Although more than 50% of patients with ADVT developed post-thrombotic changes according to ultrasound, these changes did not result in haemodynamically significant venous dysfunction
Q^2 Evolution of Generalized Baldin Sum Rule for the Proton
The generalized Baldin sum rule for virtual photon scattering, the
unpolarized analogy of the generalized Gerasimov-Drell-Hearn integral, provides
an important way to investigate the transition between perturbative QCD and
hadronic descriptions of nucleon structure. This sum rule requires integration
of the nucleon structure function F_1, which until recently had not been
measured at low Q^2 and large x, i.e. in the nucleon resonance region. This
work uses new data from inclusive electron-proton scattering in the resonance
region obtained at Jefferson Lab, in combination with SLAC deep inelastic
scattering data, to present first precision measurements of the generalized
Baldin integral for the proton in the Q^2 range of 0.3 to 4.0 GeV^2.Comment: 4 pages, 3 figures, one table; text added, one figure replace
A multifractal zeta function for cookie cutter sets
Starting with the work of Lapidus and van Frankenhuysen a number of papers
have introduced zeta functions as a way of capturing multifractal information.
In this paper we propose a new multifractal zeta function and show that under
certain conditions the abscissa of convergence yields the Hausdorff
multifractal spectrum for a class of measures
Survey of charge symmetry breaking operators for dd -> alpha pi0
The charge-symmetry-breaking amplitudes for the recently observed d d ->
alpha pi0 reaction are investigated. Chiral perturbation theory is used to
classify and identify the leading-order terms. Specific forms of the related
one- and two-body tree level diagrams are derived. As a first step toward a
full calculation, a few tree-level two-body diagrams are evaluated at each
considered order, using a simplified set of d and alpha wave functions and a
plane-wave approximation for the initial dd state. The leading-order
pion-exchange term is shown to be suppressed in this model because of poor
overlap of the initial and final states. The higher-order one-body and
short-range (heavy-meson-exchange) amplitudes provide better matching between
the initial and final states and therefore contribute significantly and
coherently to the cross section. The consequences this might have for a full
calculation, with realistic wave functions and a more complete set of
amplitudes, are discussed.Comment: REVTeX 4, 35 pages, 8 eps figures, submitted to PR
Coulomb-hadron phase factor and spin phenomena in a wide region of transfer momenta
The Coulomb-hadron interference effects are examined at small and large .
The methods for the definition of spin-dependent parts of hadron scattering
amplitude are presented. The additional contributions to analyzing power
and the double spin correlation parameter owing to the
electromagnetic-hadron interference are determined in the diffraction dip
domain of high-energy elastic hadron scattering.Comment: 9 pages, LaTeX, 4 figure
Impact of saturation on spin effects in proton-proton scattering
For pomerons described by a sum of two simple-pole terms, a soft and a hard
pomeron, the unitarity bounds from saturation in impact-parameter space are
examined. We consider the effect of these bounds on observables linked with
polarisation, such as the analyzing power in elastic proton-proton scattering,
for LHC energies. We obtain the s and t dependence of the Coulomb-nuclear
interference at small momentum transfer, and show that the effect of the hard
pomeron may be observed at the LHC.Comment: 8 pages, 2 figures, presented by O.V.S. at the Advanced Studies
Institute "Symetries and Spin" (SPIN-Praha-2004), Prague, July 5 - July 10,
200
- …