804 research outputs found
Absence of static phase separation in the high-Tc cuprate
We use 89Y NMR in in order to evaluate with high
sensitivity the distribution of hole content p in the CuO2 planes. For y=1 and
y=0.6, this hole doping distribution is found narrow with a full width at half
maximum smaller than Delta p=0.025. This rules out any large static phase
separation between underdoped and optimally doped regions in contrast with the
one observed by STM in Bi2212 and by NQR in LaSrCuO. This establishes that
static electronic phase separation is not a generic feature of the cuprates.Comment: published in Phys.Rev.Lett. 89, 157002 (2002) (only minor changes as
compared to previous version) Article of 4 pages + 3 figure
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Changes in aroma and sensory profile of food ingredients smoked in the presence of a zeolite filter
During smoking, formation of desirable smoky compounds and carcinogenic polycyclic aromatic hydrocarbons (PAH) are inextricably linked. We have previously developed a zeolite filter technology (PureSmoke Technology or PST) that reduces the PAH content of a smoke stream, particularly reducing the concentration of benzo[a]pyrene, a known carcinogen, by up to 93%. The aim of this work was to determine whether there were changes in the volatile and sensory profiles of ingredients smoked using PST compared to the traditional smoking process (Trad). Smoked tomato flakes (either PST or Trad) were added to either low-fat or full-fat cream cheese for sensory profiling and consumer preference tests, and volatile analysis was carried out using solid phase microextraction (SPME) followed by gas chromatography-mass spectrometry (GC-MS). The sensory analysis showed a significant decrease (p < 0.01) in bitterness when the PST was employed and a significant decrease in overall smoky aroma and flavor (p < 0.001), which resulted in an increase in the perception of cheesy aroma and flavor. This was consistent with a decrease in many of the smoky aroma compounds, particularly the guaiacols. However, consumer preference tests showed that there was no adverse effect on the flavor of the products, and there was even a tendency for the PST product to be preferred to the Trad product (p = 0.096). The smoke compounds were quantitated and compared in smoked tomato paste. Odor activity values (OAVs) calculated from the literature thresholds suggested that guaiacol and 4-alk(en)yl-substituted guaiacols are likely to be among the most highly odor-active compounds in these smoked ingredients
Dynamical Processing of Geophysical Signatures based on SPOT-5 Remote Sensing Imagery
An intelligent post-processing computational paradigm based on the use of dynamical filtering techniques modified to enhance the quality of reconstruction of geophysical signatures based on Spot-5 imagery is proposed. As a matter of particular study, a robust algorithm is reported for the analysis of the dynamic behavior of geophysical indexes extracted from the real-world remotely sensed scenes. The simulation results verify the efficiency of the approach as required for decision support in resources management
Teleparallel Spin Connection
A new expression for the spin connection of teleparallel gravity is proposed,
given by minus the contorsion tensor plus a zero connection. The corresponding
minimal coupling is covariant under local Lorentz transformation, and
equivalent to the minimal coupling prescription of general relativity. With
this coupling prescription, therefore, teleparallel gravity turns out to be
fully equivalent to general relativity, even in the presence of spinor fields.Comment: 2 pages, RevTeX, to appear in Phys. Rev D (Brief Report
Energy of general 4-dimensional stationary axisymmetric spacetime in the teleparallel geometry
The field equation with the cosmological constant term is derived and the
energy of the general 4-dimensional stationary axisymmetric spacetime is
studied in the context of the hamiltonian formulation of the teleparallel
equivalent of general relativity (TEGR). We find that, by means of the integral
form of the constraints equations of the formalism naturally without any
restriction on the metric parameters, the energy for the asymptotically flat/de
Sitter/Anti-de Sitter stationary spacetimes in the Boyer-Lindquist coordinate
can be expressed as . It is surprised to learn that the
energy expression is relevant to the metric components ,
and only. As examples, by using this formula
we calculate the energies of the Kerr-Newman (KN), Kerr-Newman Anti-de Sitter
(KN-AdS), Kaluza-Klein, and Cveti\v{c}-Youm spacetimes.Comment: 12 page
The longitudinal structure function F_L: perturbative QCD and k_T-factorization versus experimental data at fixed W
We use results for the structure functions for a gluon target having
nonzero transverse momentum square at order , obtained in our
previous paper, to compare with recent H1 experimental data for at fixwd
W values and with collinear GRV predictions at LO and NLO approximation.Comment: 10 pages, 4 figure
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Can automobile insurance telematics predict the risk of near-miss events?
Telematics data from usage-based motor insurance provide valuable information âincluding vehicle usage, attitude towards speeding, time and proportion of urban/non-urban driving âthat can be used for rate making. Additional information on acceleration, braking and cornering can likewise be usefully employed to identify near-miss events, a concept taken from aviation that denotes a situation that may have resulted in an accident. We analyze near-miss events from a sample of driversin order to identify the risk factors associated with a higher risk of near-miss occurrence. Our empirical application witha pilot sample of real usage-based insurance data reveals that certain factors are associated with a higher expected number of near-miss events, but that the association differs depending on the type of near-miss. We conclude that night time driving is associated with a lower risk of cornering events, urban driving increases the risk of braking events and speeding is associated with acceleration events. These results are relevant for the insurance industry in order to implement dynamic risk monitoring through telematics, as well as preventive actions
Quantum effective actions from nonperturbative worldline dynamics
We demonstrate the feasibility of a nonperturbative analysis of quantum field
theory in the worldline formalism with the help of an efficient numerical
algorithm. In particular, we compute the effective action for a
super-renormalizable field theory with cubic scalar interaction in four
dimensions in quenched approximation (small- expansion) to all orders in
the coupling. We observe that nonperturbative effects exert a strong influence
on the infrared behavior, rendering the massless limit well defined in contrast
to the perturbative expectation. Our numerical method is based on a direct use
of probability distributions for worldline ensembles, preserves all Euclidean
spacetime symmetries, and thus represents a new nonperturbative tool for an
investigation of continuum quantum field theory.Comment: 33 pages, 10 figure
Gravitational Energy-Momentum Density in Teleparallel Gravity
In the context of a gauge theory for the translation group, a conserved
energy-momentum gauge current for the gravitational field is obtained. It is a
true spacetime and gauge tensor, and transforms covariantly under global
Lorentz transformations. By rewriting the gauge gravitational field equation in
a purely spacetime form, it becomes the teleparallel equivalent of Einstein's
equation, and the gauge current reduces to the M{\o}ller's canonical
energy-momentum density of the gravitational field.Comment: RevTeX, 4 pages, no figures, to appear in Phys. Rev. Let
Exchange Interaction and in Alkaline-earth-metal-oxide-based DMS without Magnetic Impurities: First Principle Pseudo-SIC and Monte Carlo Calculation
The prospects of half-metallic ferromagnetism being induced by the
incorporation of C atoms into alkaline-earth-metal-oxides are investigated by
the first principle calculation. The origin of the ferromagnetism is discussed
through the calculation of the electronic structure and exchange coupling
constant by using the pseudo-potential-like self-interaction-corrected local
spin density method. The Curie temperature () is also predicted by
employing the Monte Carlo simulation. It is shown that by taking the electron
self-interaction into account, the half-metallic ferromagnetism induced by C in
the host materials is more stabilized in comparison with the standard LDA case,
and the C's electron states in the bandgap become more localized resulting
in the predominance of the short-ranged exchange interaction. While the
ferromagnetism in MgOC is stabilized due to the exchange
interaction of the -nearest neighbor pairs and might be suppressed by the
anti-ferromagnetic super-exchange interaction at higher , the ferromagnetism
in CaOC, SrOC, and BaOC is stabilized by
both the - and -nearest neighbor pairs, and monotonously
increases with the C concentration.Comment: 5 pages, 5 figure
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