48,925 research outputs found
Oocyte cryopreservation as an adjunct to the assisted reproductive technologies
The document attached has been archived with permission from the editor of the Medical Journal of Australia. An external link to the publisher’s copy is included. See page 2 of PDF for this item.Keith L Harrison, Michelle T Lane, Jeremy C Osborn, Christine A Kirby, Regan Jeffrey, John H Esler and David Mollo
Towards Meson Spectroscopy Instead of Bump Hunting
Mesonic resonances are generally observed in data as narrow, moderately
broad, or wide peaks in scattering or production processes. In the eyes of
nearly all experimentalists, any suchlike bump is a true resonance as soon as
its statistical significance exceeds certain minimal values. However, this
simple point of view ignores possible effects from competing hadronic channels
and the opening of the corresponding thresholds. On the other hand, most
theoretical hadron-model builders consider mesons merely bound states of a
quark and an antiquark, or of more exotic combinations sometimes involving
valence gluons as well. Also the latter description is much too naive, since
considerable mass shifts or even the dynamical generation of extra states due
to unquenching are equally ignored.
In the present paper, a largely empirical yet very successful approach to
meson spectroscopy is revisited, in which all the above phenomena can be
accounted for non-perturbatively, with concrete examples of some enigmatic
mesonic states described in detail. First, the X(4260) charmonium enhancement
is argued to be a non-resonant structure resulting from depletion effects due
to competing channels and resonances. Then, the X(3872) charmonium-like meson
is described as a unitarised state. Also, the
unusual pattern of masses and widths of the open-charm axial-vector mesons
, , , and is shown to follow
from highly non-perturbative coupled-channel and mixing effects. Finally, first
indications of a very light scalar boson are presented, on the basis of
published BABAR data.Comment: Invited seminar given by G. Rupp at the International School of
Nuclear Physics, 33rd course: "From Quarks and Gluons to Hadrons and Nuclei",
Erice, Sicily, Italy, 16 - 24 September 2011; 7 pages, 5 figures (9 plots),
style of Progress in Particle and Nuclear Physic
Adaptive Gaussian Markov Random Fields with Applications in Human Brain Mapping
Functional magnetic resonance imaging (fMRI) has become the standard technology in human brain mapping. Analyses of the massive spatio-temporal fMRI data sets often focus on parametric or nonparametric modeling of the temporal component, while spatial smoothing is based on Gaussian kernels or random fields. A weakness of Gaussian spatial smoothing is underestimation of activation peaks or blurring of high-curvature transitions between activated and non-activated brain regions. In this paper, we introduce a class of inhomogeneous Markov random fields (MRF) with spatially adaptive interaction weights in a space-varying coefficient model for fMRI data. For given weights, the random field is conditionally Gaussian, but marginally it is non-Gaussian. Fully Bayesian inference, including estimation of weights and variance parameters, is carried out through efficient MCMC simulation. An application to fMRI data from a visual stimulation experiment demonstrates the performance of our approach in comparison to Gaussian and robustified non-Gaussian Markov random field models
Hoag's Object: Evidence for Cold Accretion onto an Elliptical Galaxy
(Abridged) We present new photometric and spectroscopic observations of the
famous Hoag's Object, a peculiar ring galaxy with a central roundish core. The
nature of Hoag's Object is still under controversial discussion. Previous
studies demonstrated that a major accretion event that took place at least 2-3
Gyr ago can account for the observational evidence. However, the role of
internal nonlinear mechanisms in forming the outer ring was not yet completely
ruled out. These new data, together with HI and optical information from the
literature, are used to demonstrate that Hoag's Object is a relatively isolated
system surrounded by a luminous quasi-spiral pattern and a massive, low-density
HI disc. The main stellar body is an old, mildly triaxial elliptical galaxy
with very high angular momentum. We review previous formation scenarios of
Hoag's Object in light of the new data and conclude that the peculiar
morphology could not represent a late phase in barred early-type galaxies
evolution. In addition, no observational evidence supports late merging events
in the evolution of the galaxy, although further tests are required before
safely dismissing this idea. We propose a new scenario where the elliptical
core formed in the early Universe with the HI disc forming shortly after the
core by prolonged "cold" accretion of primordial gas from the intergalactic
medium. The low gas density does not allow intense star formation to occur
everywhere in the disc, but only along a tightly wound spiral pattern of
enhanced density induced by the triaxial gravitational potential.Comment: 18 pages, 12 figures. MNRAS in press, minor changes to match
published versio
Book Review: \u3ci\u3eRitual Participation and Interreligious Dialogue: Boundaries, Transgressions and Innovations\u3c/i\u3e
Book review of Ritual Participation and Interreligious Dialogue: Boundaries, Transgressions and Innovations. Edited by Marianne Moyaert and Joris Geldhof. London and New York: Bloomsbury, 2015. ix + 262 pages
Finite-element analysis on cantilever beams coated with magnetostrictive material
The main focus of this paper is to highlight some of the key criteria in successful utilization of magnetostrictive materials within a cantilever based microelectromechanical system (MEMS). The behavior of coated cantilever beams is complex and many authors have offered solutions using analytical techniques. In this study, the FEMLAB finite-element multiphysics package was used to incorporate the full magnetostrictive strain tensor and couple it with partial differential equations from structural mechanics to solve simple cantilever systems. A wide range of geometries and material properties were solved to study the effects on cantilever deflection and the system resonance frequencies. The latter were found by the use of an eigen-frequency solver. The models have been tailored for comparison with other such data within the field and results also go beyond previous work
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