10,439 research outputs found
Surface electrical properties experiment. Part 2: Theory of radio-frequency interferometry in geophysical subsurface probing
The radiation fields due to a horizontal electric dipole laid on the surface of a stratified medium were calculated using a geometrical optics approximation, a modal approach, and direct numerical integration. The solutions were obtained from the reflection coefficient formulation and written in integral forms. The calculated interference patterns are compared in terms of the usefulness of the methods used to obtain them. Scattering effects are also discussed and all numerical results for anisotropic and isotropic cases are presented
Tm3+/Ho3+ codoped tellurite fiber laser
Continuous-wave and Q-switched lasing from a Tm 3+ /Ho 3+ codoped tellurite fiber is reported. An Yb 3+ /Er 3+ -doped silica fiber laser operating at 1.6Ī¼m was used as an in-band pump source, exciting the Tm 3+ ions into the F 4 3 level. Energy is then nonradiatively transferred to the upper laser level, the I 7 5 state of Ho 3+ . The laser transition is from the I 7 5 level to the I 8 5 level, and the resulting emission is at 2.1Ī¼m . For continuous wave operation, the slope efficiency was 62% and the threshold 0.1W ; the maximum output demonstrated was 0.16W . Mechanical Q switching resulted in a pulse of 0.65Ī¼J energy and 160ns duration at a repetition rate of 19.4kHz
Heavy Domain Wall Fermions: The RBC and UKQCD charm physics program
We review the domain wall charm physics program of the RBC and UKQCD
collaborations based on simulations including ensembles with physical pion
mass. We summarise our current set-up and present a status update on the decay
constants , , the charm quark mass, heavy-light and heavy-strange
bag parameters and the ratio .Comment: 8 pagers, 4 figures, conference proceedings for Lattice2017 submitted
to EPJ Web of Conference
Osteoblast interactions within a biomimetic apatite microenvironment.
Numerous reports have shown that accelerated apatites can mediate osteoblastic differentiation in vitro and bone formation in vivo. However, how cells interact within the apatite microenvironment remains largely unclear, despite the vast literature available today. In response, this study evaluates the in vitro interactions of a well-characterized osteoblast cell line (MC3T3-E1) with the apatite microenvironment. Specifically, cell attachment, spreading, and viability were evaluated in the presence and absence of serum proteins. Proteins were found to be critical in the mediation of cell-apatite interactions, as adherence of MC3T3-E1 cells to apatite surfaces without protein coatings resulted in significant levels of cell death within 24Ā h in serum-free media. In the absence of protein-apatite interaction, cell viability could be "rescued" upon treatment of MC3T3-E1 cells with inhibitors to phosphate (PO(4) (3-)) transport, suggesting that PO(4) (3-) uptake may play a role in viability. In contrast, rescue was not observed upon treatment with calcium (Ca(2+)) channel inhibitors. Interestingly, a rapid "pull-down" of extracellular Ca(2+) and PO(4) (3-) ions onto the apatite surface could be measured upon the incubation of apatites with Ī±-MEM, suggesting that cells may be subject to changing levels of Ca(2+) and PO(4) (3-) within their microenvironment. Therefore, the biomimetic apatite surface may significantly alter the microenvironment of adherent osteoblasts and, as such, be capable of affecting both cell survival and differentiation
Quantum theory of optical temporal phase and instantaneous frequency. II. Continuous time limit and state-variable approach to phase-locked loop design
We consider the continuous-time version of our recently proposed quantum
theory of optical temporal phase and instantaneous frequency [Tsang, Shapiro,
and Lloyd, Phys. Rev. A 78, 053820 (2008)]. Using a state-variable approach to
estimation, we design homodyne phase-locked loops that can measure the temporal
phase with quantum-limited accuracy. We show that post-processing can further
improve the estimation performance, if delay is allowed in the estimation. We
also investigate the fundamental uncertainties in the simultaneous estimation
of harmonic-oscillator position and momentum via continuous optical phase
measurements from the classical estimation theory perspective. In the case of
delayed estimation, we find that the inferred uncertainty product can drop
below that allowed by the Heisenberg uncertainty relation. Although this result
seems counter-intuitive, we argue that it does not violate any basic principle
of quantum mechanics.Comment: 11 pages, 6 figures, v2: accepted by PR
Temperature determination from the lattice gas model
Determination of temperature from experimental data has become important in
searches for critical phenomena in heavy ion collisions. Widely used methods
are ratios of isotopes (which rely on chemical and thermal equilibrium),
population ratios of excited states etc. Using the lattice gas model we propose
a new observable: where is the charge multiplicity and
is the charge of the fragmenting system. We show that the reduced multiplicity
is a good measure of the average temperature of the fragmenting system.Comment: 11 pages, 2 ps file
Probing nuclear symmetry energy with the sub-threshold pion production
Within the framework of semiclassical Boltzmann-Uehling-Uhlenbeck (BUU)
transport model, we investigated the effects of symmetry energy on the
sub-threshold pion using the isospin MDI interaction with the stiff and soft
symmetry energies in the central collision of Ca + Ca at the
incident beam energies of 100, 150, 200, 250 and 300 MeV/nucleon, respectively.
We find that the ratio of of sub-threshold charged pion
production is greatly sensitive to the symmetry energy, particularly around 100
MeV/nucleon energies. Large sensitivity of sub-threshold charged pion
production to nuclear symmetry energy may reduce uncertainties of probing
nuclear symmetry energy via heavy-ion collision.Comment: 5 pages, 5 figures, typo corrections, submitted to Chinese Physics
Letter
An exploratory study of heavy domain wall fermions on the lattice
We report on an exploratory study of domain wall fermions (DWF) as a lattice
regularisation for heavy quarks. Within the framework of quenched QCD with the
tree-level improved Symanzik gauge action we identify the DWF parameters which
minimise discretisation effects. We find the corresponding effective 4
overlap operator to be exponentially local, independent of the quark mass. We
determine a maximum bare heavy quark mass of , below which the
approximate chiral symmetry and O(a)-improvement of DWF are sustained. This
threshold appears to be largely independent of the lattice spacing. Based on
these findings, we carried out a detailed scaling study for the heavy-strange
meson dispersion relation and decay constant on four ensembles with lattice
spacings in the range . We observe very mild
scaling towards the continuum limit. Our findings establish a sound basis for
heavy DWF in dynamical simulations of lattice QCD with relevance to Standard
Model phenomenology.Comment: 23 pages, 8 figure
Appendix to theory of radio-frequency interferometry in geophysical subsurface probing, numerical results
A series of interference and radiation patterns are presented for radio interferometry in subsurface probing. The interference patterns are due both to a vertical magnetic dipole and to a horizontal electric dipole. Mode solutions are also presented for layer thickness equal to 1 wavelength, as well as for thin layers
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