326 research outputs found
Effective theory of the Delta(1232) in Compton scattering off the nucleon
We formulate a new power-counting scheme for a chiral effective field theory
of nucleons, pions, and Deltas. This extends chiral perturbation theory into
the Delta-resonance region. We calculate nucleon Compton scattering up to
next-to-leading order in this theory. The resultant description of existing
p cross section data is very good for photon energies up to about 300
MeV. We also find reasonable numbers for the spin-independent polarizabilities
and .Comment: 29 pp, 9 figs. Minor revisions. To be published in PR
Multi-Periodic Oscillations in Cepheids and RR Lyrae-Type Stars
Classical Cepheids and RR Lyrae-type stars are usually considered to be
textbook examples of purely radial, strictly periodic pulsators. Not all the
variables, however, conform to this simple picture. In this review I discuss
different forms of multi-periodicity observed in Cepheids and RR Lyrae stars,
including Blazhko effect and various types of radial and nonradial multi-mode
oscillations.Comment: Proceedings of the 20th Stellar Pulsation Conference Series: "Impact
of new instrumentation & new insights in stellar pulsations", 5-9 September
2011, Granada, Spai
Toward an internally consistent astronomical distance scale
Accurate astronomical distance determination is crucial for all fields in
astrophysics, from Galactic to cosmological scales. Despite, or perhaps because
of, significant efforts to determine accurate distances, using a wide range of
methods, tracers, and techniques, an internally consistent astronomical
distance framework has not yet been established. We review current efforts to
homogenize the Local Group's distance framework, with particular emphasis on
the potential of RR Lyrae stars as distance indicators, and attempt to extend
this in an internally consistent manner to cosmological distances. Calibration
based on Type Ia supernovae and distance determinations based on gravitational
lensing represent particularly promising approaches. We provide a positive
outlook to improvements to the status quo expected from future surveys,
missions, and facilities. Astronomical distance determination has clearly
reached maturity and near-consistency.Comment: Review article, 59 pages (4 figures); Space Science Reviews, in press
(chapter 8 of a special collection resulting from the May 2016 ISSI-BJ
workshop on Astronomical Distance Determination in the Space Age
Measurement of the B0-anti-B0-Oscillation Frequency with Inclusive Dilepton Events
The - oscillation frequency has been measured with a sample of
23 million \B\bar B pairs collected with the BABAR detector at the PEP-II
asymmetric B Factory at SLAC. In this sample, we select events in which both B
mesons decay semileptonically and use the charge of the leptons to identify the
flavor of each B meson. A simultaneous fit to the decay time difference
distributions for opposite- and same-sign dilepton events gives ps.Comment: 7 pages, 1 figure, submitted to Physical Review Letter
Comunidades de morcegos em hábitats de uma Mata Amazônica remanescente na Ilha de São Luís, Maranhão
Mechanical performance and healing patterns of the novel sirolimus-eluting bioresorbable Fantom scaffold: 6-month and 9-month follow-up by optical coherence tomography in the FANTOM II study
Objectives We aimed to evaluate the mechanical properties
and healing patterns 6 and 9 months after implantation of the
sirolimus-eluting Fantom bioresorbable scaffold (BRS).
Background The Fantom BRS (Reva Medical, San Diego,
USA) has differentiating properties including radiopacity,
strut thickness of 125 µm, high expansion capacity and
has demonstrated favourable mid-term clinical and
angiographic outcomes.
Methods and results FANTOM II was a prospective,
single arm study with implantation of the Fantom BRS
in 240 patients with stable angina pectoris. Guidance by
optical coherence tomography (OCT) was encouraged and
was repeated at 6-month (cohort A) or 9-month follow-up
(cohort B). Matched baseline and follow-up OCT recordings
were available in 152 patients. In-scaffold mean lumen
area in cohort A was 6.8±1.7mm2
and 5.7±1.4mm2
at baseline and follow-up (p<0.0001) and was
7.2±1.6mm2
and 5.6±1.4mm2
in cohort B (p<0.0001).
Mean scaffold area remained stable from 7.1±1.5mm2
at baseline to 7.2±1.4mm2
at 6 months (p=0.12), and
from 7.4±1.5mm2
to 7.3±1.4mm2
at 9 months. Strut
malapposition was median 0.8 (IQR 0.0;3.5)% and 1.8 (IQR
0.3;6.0)% at baseline and was 0.0 (IQR 0.0;0.0)% in both
groups at 6-month and 9-month follow-up. Strut tissue
coverage was 98.1 (IQR 95.9;99.4)% at 6 months and
98.9 (IQR 98.3;100.0)% at 9 months.
Conclusions The novel Fantom BRS had favourable
healing patterns at 6-month and 9-month follow-up as
malapposition was effectively resolved and strut coverage
was almost complete. The scaffold remained stable
through follow-up with no signs of systematic late recoil
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