120 research outputs found
An Exploratory Study of User Perceptions of Payment Methods in the UK and the US
This paper presents the design and the results of a
cross-cultural study of user perceptions and attitudes toward electronic payment methods. We conduct a series of semi-structured interviews involving forty participants (20 in London, UK, and 20 in Manhattan, KS, USA) to explore how individuals use the mechanisms available to them within their routine payment and banking activities. We also study their comprehension of payment processes, the perceived effort and impact of using different methods, as well as direct or indirect recollections of (suspected or actual) fraud and related interactions with banks and retailers. By comparing UK and US participants, we also elicit commonalities and differences that may help better understand, if not predict, attitudes of US customers once technologies like Chip-and-PIN are rolled out – for instance, several US participants were confused by how to use it, while UK participants found it convenient. Our results show that purchasing habits as well as the availability of rewards schemes are primary criteria influencing choices relating to payment technologies, and that inconsistencies, glitches, and other difficulties with newer technologies generate frustration sometimes leading to complete avoidance of new payment methods
Hadron Production via e+e- Collisions with Initial State Radiation
A novel method of studying e+e- annihilation into hadrons using initial state
radiation at e+e- colliders is described. After brief history of the method,
its theoretical foundations are considered. Numerous experiments in which
exclusive cross sections of e+e- annihilation into hadrons below the
center-of-mass energy of 5 GeV have been measured are presented. Some
applications of the results obtained to fundamental tests of the Standard Model
are listed.Comment: 50 pages, 88 figures, accepted for publication in Rev. Mod. Phy
A constraint on antigravity of antimatter from precision spectroscopy of simple atoms
Consideration of antigravity for antiparticles is an attractive target for
various experimental projects. There are a number of theoretical arguments
against it but it is not quite clear what kind of experimental data and
theoretical suggestions are involved. In this paper we present straightforward
arguments against a possibility of antigravity based on a few simple
theoretical suggestions and some experimental data. The data are: astrophysical
data on rotation of the Solar System in respect to the center of our galaxy and
precision spectroscopy data on hydrogen and positronium. The theoretical
suggestions for the case of absence of the gravitational field are: equality of
electron and positron mass and equality of proton and positron charge. We also
assume that QED is correct at the level of accuracy where it is clearly
confirmed experimentally
Formalism for dilepton production via virtual photon bremsstrahlung in hadronic reactions
We derive a set of new formulas for various distributions in dilepton
production via virtual photon bremsstrahlung from pseudoscalar mesons and
unpolarized spin-one-half fermions. These formulas correspond to the leading
and sub-leading terms in the Low-Burnett-Kroll expansion for real photon
bremsstrahlung. The relation of our leading-term formulas to previous works is
also shown. Existing formulas are examined in the light of Lorentz covariance
and gauge invariance. Numerical comparison is made in a simple example, where
an "exact" formula and real photon data exist. The results reveal large
discrepancies among different bremsstrahlung formulas. Of all the leading-term
bremsstrahlung formulas, the one derived in this work agrees best with the
exact formula. The issues of M_T-scaling and event generators are also
addressed.Comment: 37 pages, RevTeX, epsf.sty, 10 embedded figure
Pion and Kaon Vector Form Factors
We develop a unitarity approach to consider the final state interaction
corrections to the tree level graphs calculated from Chiral Perturbation Theory
() allowing the inclusion of explicit resonance fields. The method is
discussed considering the coupled channel pion and kaon vector form factors.
These form factors are then matched with the one loop results. A very
good description of experimental data is accomplished for the vector form
factors and for the P-wave phase shifts up to
GeV, beyond which multiparticle states play a non negligible role. In
particular the low and resonance energy regions are discussed in detail and for
the former a comparison with one and two loop is made showing a
remarkable coincidence with the two loop results.Comment: 20 pages, 7 figs, to appear in Phys. Rev.
Use of submicron vaterite particles serves as an effective delivery vehicle to the respiratory portion of the lung
© 2018 Gusliakova, Atochina-Vasserman, Sindeeva, Sindeev, Pinyaev, Pyataev, Revin, Sukhorukov, Gorin and Gow. Nano- and microencapsulation has proven to be a useful technique for the construction of drug delivery vehicles for use in vascular medicine. However, the possibility of using these techniques within the lung as an inhalation delivery mechanism has not been previously considered. A critical element of particle delivery to the lung is the degree of penetrance that can be achieved with respect to the airway tree. In this study we examined the effectiveness of near infrared (NIR) dye (Cy7) labeled calcium carbonate (vaterite) particles of 3.15, 1.35, and 0.65 μm diameter in reaching the respiratory portion of the lung. First of all, it was shown that, interaction vaterite particles and the components of the pulmonary surfactant occurs a very strong retardation of the recrystallization and dissolution of the particles, which can subsequently be used to create systems with a prolonging release of bioactive substances after the particles penetrate the distal sections of the lungs. Submicro- and microparticles, coated with Cy7 labeled albumin as a model compound, were delivered to mouse lungs via tracheostomy with subsequent imaging performed 24, 48, and 72 h after delivery by in vivo fluorescence. 20 min post administration particles of all three sizes were visible in the lung, with the deepest penetrance observed with 0.65 μm particles. In vivo biodistribution was confirmed by fluorescence tomography imaging of excised organs post 72 h. Laser scanning confocal microscopy shows 0.65 μm particles reaching the alveolar space. The delivery of fluorophore to the blood was assessed using Cy7 labeled 0.65 μm particles. Cy7 labeled 0.65 μm particles efficiently delivered fluorescent material to the blood with a peak 3 h after particle administration. The pharmacokinetics of NIR fluorescence dye will be shown. These studies establish that by using 0.65 μm particles loaded with Cy7 we can efficiently access the respiratory portion of the lung, which represents a potentially efficient delivery mechanism for both the lung and the vasculature
Hadronic Structure in the Decay
We report on a study of the invariant mass spectrum of the hadronic system in
the decay tau- -> pi- pi0 nu_tau. This study was performed with data obtained
with the CLEO II detector operating at the CESR e+ e- collider. We present fits
to phenomenological models in which resonance parameters associated with the
rho(770) and rho(1450) mesons are determined. The pi- pi0 spectral function
inferred from the invariant mass spectrum is compared with data on e+ e- -> pi+
pi- as a test of the Conserved Vector Current theorem. We also discuss the
implications of our data with regard to estimates of the hadronic contribution
to the muon anomalous magnetic moment.Comment: 39 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLN
Study of the process in the energy region 400<\sqrt[]{s}<1000 MeV
The cross section of the process e^+e^-\to \pi^+\pi^- was measured in the SND
experiment at the VEPP-2M collider in the energy region 400<\sqrt[]{s}<1000
MeV. This measurement was based on about 12.4 \times 10^6 selected collinear
events, which include 7.4\times 10^6 e^+e^-\to e^+e^-, 4.5\times 10^6
e^+e^-\to\pi^+\pi^- and 0.5\times 10^6 e^+e^-\to\mu^+\mu^- selected events. The
systematic uncertainty of the cross section determination is 1.3 %. The
\rho-meson parameters were determined: m_\rho=774.9\pm 0.4\pm 0.5 MeV,
\Gamma_\rho=146.5\pm 0.8\pm 1.5 MeV, \sigma(\rho\to\pi^+\pi^-)=1220\pm 7\pm 16
nb as well as the parameters of the G-parity suppressed decay
\omega\to\pi^+\pi^-: \sigma(\omega\to\pi^+\pi^-)=29.9\pm 1.4\pm 1.0 nb and
\phi_{\rho\omega} = 113.5\pm 1.3\pm 1.7 degree.Comment: 30 pages REVTEX and 31 figure
The Physics of Hadronic Tau Decays
Hadronic tau decays represent a clean laboratory for the precise study of
quantum chromodynamics (QCD). Observables (sum rules) based on the spectral
functions of hadronic tau decays can be related to QCD quark-level calculations
to determine fundamental quantities like the strong coupling constant,
parameters of the chiral Lagrangian, |V_us|, the mass of the strange quark, and
to simultaneously test the concept of quark-hadron duality. Using the best
available measurements and a revisited analysis of the theoretical framework,
the value alpha_s(m_tau) = 0.345 +- 0.004[exp] +- 0.009[theo] is obtained.
Taken together with the determination of alpha_s(m_Z) from the global
electroweak fit, this result leads to the most accurate test of asymptotic
freedom: the value of the logarithmic slope of 1/alpha_s(s) is found to agree
with QCD at a precision of 4%. In another approach, the tau spectral functions
can be used to determine hadronic quantities that, due to the nonperturbative
nature of long-distance QCD, cannot be computed from first principles. An
example for this is the contribution from hadronic vacuum polarization to
loop-dominated processes like the anomalous magnetic moment of the muon. This
article reviews the measurements of nonstrange and strange tau spectral
functions and their phenomenological applications.Comment: 89 pages, 32 figures; final version accepted for publication by
Reviews of Modern Physic
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