3,307 research outputs found
High precision U-Pb zircon ages for Mesozoic igneous rocks from Hong Kong
Sixteen new high precision U–Pb zircon ages are reported from Jurassic and Early Cretaceous silicic volcanic and plutonic rocks of HongKong. When combined with the existing age dataset, the new ages constrain more tightly the timing of major periods of volcanism and plutonism at 162.6 ± 4.5 Ma, 146.7 ± 1.1 Ma, 143.0 ± 1.0 Ma and 140.8 ± 0.6 Ma. However, two ages of 151.9 ± 0.2 Ma and 148.1 ± 0.2 Ma, from eastern New Territories and southern HongKong indicate additional and therefore more continuous, albeit pulsed, magmatic activity than previously thought
Smooth vortex precession in superfluid 4He
We have measured a precessing superfluid vortex line, stretched from a wire
to the wall of a cylindrical cell. By contrast to previous experiments with a
similar geometry, the motion along the wall is smooth. The key difference is
probably that our wire is substantially off center. We verify several numerical
predictions about the motion, including an asymmetry in the precession
signature, the behavior of pinning events, and the temperature dependence of
the precession.Comment: 8 pages, 8 figure
Guidelines for the use of cell lines in biomedical research
Cell-line misidentification and contamination with microorganisms, such as mycoplasma, together with instability, both genetic and phenotypic, are among the problems that continue to affect cell culture. Many of these problems are avoidable with the necessary foresight, and these Guidelines have been prepared to provide those new to the field and others engaged in teaching and instruction with the information necessary to increase their awareness of the problems and to enable them to deal with them effectively. The Guidelines cover areas such as development, acquisition, authentication, cryopreservation, transfer of cell lines between laboratories, microbial contamination, characterisation, instability and misidentification. Advice is also given on complying with current legal and ethical requirements when deriving cell lines from human and animal tissues, the selection and maintenance of equipment and how to deal with problems that may arise
Crossing Statistic: Bayesian interpretation, model selection and resolving dark energy parametrization problem
By introducing Crossing functions and hyper-parameters I show that the
Bayesian interpretation of the Crossing Statistics [1] can be used trivially
for the purpose of model selection among cosmological models. In this approach
to falsify a cosmological model there is no need to compare it with other
models or assume any particular form of parametrization for the cosmological
quantities like luminosity distance, Hubble parameter or equation of state of
dark energy. Instead, hyper-parameters of Crossing functions perform as
discriminators between correct and wrong models. Using this approach one can
falsify any assumed cosmological model without putting priors on the underlying
actual model of the universe and its parameters, hence the issue of dark energy
parametrization is resolved. It will be also shown that the sensitivity of the
method to the intrinsic dispersion of the data is small that is another
important characteristic of the method in testing cosmological models dealing
with data with high uncertainties.Comment: 14 pages, 4 figures, discussions extended, 1 figure and two
references added, main results unchanged, matches the final version to be
published in JCA
The Evolution and Long-Term Results of Laparoscopic Antireflux Surgery for the Treatment of Gastroesophageal Reflux Disease
When carefully performed, laparoscopic antireflux surgery is an effective, durable procedure for the control of gastroesophageal reflux disease
Thermodynamics of an interacting trapped Bose-Einstein gas in the classical field approximation
We present a convenient technique describing the condensate in dynamical
equilibrium with the thermal cloud, at temperatures close to the critical one.
We show that the whole isolated system may be viewed as a single classical
field undergoing nonlinear dynamics leading to a steady state. In our procedure
it is the observation process and the finite detection time that allow for
splitting the system into the condensate and the thermal cloud.Comment: 4 pages, 4 eps figures, final versio
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