14,011 research outputs found
Weak Wave Turbulence Scaling Theory for Diffusion and Relative Diffusion in Turbulent Surface Waves
We examine the applicability of the weak wave turbulence theory in explaining
experimental scaling results obtained for the diffusion and relative diffusion
of particles moving on turbulent surface waves. For capillary waves our
theoretical results are shown to be in good agreement with experimental
results, where a distinct crossover in diffusive behavior is observed at the
driving frequency. For gravity waves our results are discussed in the light of
ocean wave studies.Comment: 5 pages; for related work visit http://www.imedea.uib.es/~victo
Root to Kellerer
We revisit Kellerer's Theorem, that is, we show that for a family of real
probability distributions which increases in convex
order there exists a Markov martingale s.t.\ .
To establish the result, we observe that the set of martingale measures with
given marginals carries a natural compact Polish topology. Based on a
particular property of the martingale coupling associated to Root's embedding
this allows for a relatively concise proof of Kellerer's theorem.
We emphasize that many of our arguments are borrowed from Kellerer
\cite{Ke72}, Lowther \cite{Lo07}, and Hirsch-Roynette-Profeta-Yor
\cite{HiPr11,HiRo12}.Comment: 8 pages, 1 figur
Stable States of Biological Organisms
A novel model of biological organisms is advanced, treating an organism as a
self-consistent system subject to a pathogen flux. The principal novelty of the
model is that it describes not some parts, but a biological organism as a
whole. The organism is modeled by a five-dimensional dynamical system. The
organism homeostasis is described by the evolution equations for five
interacting components: healthy cells, ill cells, innate immune cells, specific
immune cells, and pathogens. The stability analysis demonstrates that, in a
wide domain of the parameter space, the system exhibits robust structural
stability. There always exist four stable stationary solutions characterizing
four qualitatively differing states of the organism: alive state, boundary
state, critical state, and dead state.Comment: Latex file, 12 pages, 4 figure
What are women's mode of birth preferences and why? A systematic scoping review.
BACKGROUND:The optimal caesarean section rate is estimated to be between 10-15%; however, it is much higher in high and many middle-income countries and continues to be lower in some middle and low-income countries. While a range of factors influence caesarean section rates, women's mode of birth preferences also play a role. The aim of this study was to map the literature in relation to women's mode of birth preferences, and identify underlying reasons for, and factors associated with, these preferences. METHOD:Using a scoping review methodology, quantitative and qualitative evidence was systematically considered. To identify studies, PubMed, Maternity and Infant Care, MEDLINE, and Web of Science were searched for the period from 2008 to 2018, and reference lists of included studies were examined. FINDINGS:A total of 65 studies were included. While the majority of women prefer a vaginal birth, between 5-20% in high-income countries and 1.4 to 50% in low-middle-income countries prefer a caesarean section. The six main reasons or factors associated with a mode of birth preference were: (1) perceptions of safety; (2) fear of pain; (3) previous birth experience; (4) encouragement and dissuasion from health professionals; (5) social and cultural influences; and (6) access to information and educational levels. CONCLUSION:To help ensure women receive the required care that is aligned with their preferences, processes of shared decision-making should be implemented. Shared decision-making has the potential to reduce the rate of unnecessary interventions, and also improve the willingness of women to accept a medically-indicated caesarean section in low-income countries
What are women's mode of birth preferences and why? A systematic scoping review
Background: The optimal caesarean section rate is estimated to be between 10–15%; however, it is much higher in high and many middle-income countries and continues to be lower in some middle and low-income countries. While a range of factors influence caesarean section rates, women's mode of birth preferences also play a role. The aim of this study was to map the literature in relation to women's mode of birth preferences, and identify underlying reasons for, and factors associated with, these preferences. Method: Using a scoping review methodology, quantitative and qualitative evidence was systematically considered. To identify studies, PubMed, Maternity and Infant Care, MEDLINE, and Web of Science were searched for the period from 2008 to 2018, and reference lists of included studies were examined. Findings: A total of 65 studies were included. While the majority of women prefer a vaginal birth, between 5–20% in high-income countries and 1.4 to 50% in low-middle-income countries prefer a caesarean section. The six main reasons or factors associated with a mode of birth preference were: (1) perceptions of safety; (2) fear of pain; (3) previous birth experience; (4) encouragement and dissuasion from health professionals; (5) social and cultural influences; and (6) access to information and educational levels. Conclusion: To help ensure women receive the required care that is aligned with their preferences, processes of shared decision-making should be implemented. Shared decision-making has the potential to reduce the rate of unnecessary interventions, and also improve the willingness of women to accept a medically-indicated caesarean section in low-income countries
Improved Orbital Parameters And Transit Monitoring For HD 156846b
HD 156846b is a Jovian planet in a highly eccentric orbit (e = 0.85) with a period of 359.55 days. The pericenter passage at a distance of 0.16 AU is nearly aligned to our line of sight, offering an enhanced transit probability of 5.4% and a potentially rich probe of the dynamics of a cool planetary atmosphere impulsively heated during close approach to a bright star (V = 6.5). We present new radial velocity (RV) and photometric measurements of this star as part of the Transit Ephemeris Refinement and Monitoring Survey. The RV measurements from the Keck-High Resolution Echelle Spectrometer reduce the predicted transit time uncertainty to 20 minutes, an order of magnitude improvement over the ephemeris from the discovery paper. We photometrically monitored a predicted transit window under relatively poor photometric conditions, from which our non-detection does not rule out a transiting geometry. We also present photometry that demonstrates stability at the millimagnitude level over its rotational timescale
The ground state of the Lithium atom in strong magnetic fields
The ground and some excited states of the Li atom in external uniform
magnetic fields are calculated by means of our 2D mesh Hartree-Fock method for
field strengths ranging from zero up to 2.35 10^8 T. With increasing field
strength the ground state undergoes two transitions involving three different
electronic configurations: for weak fields the ground state configuration
arises from the field-free 1s^22s configuration, for intermediate fields from
the 1s^22p_{-1} configuration and in high fields the 1s2p_{-1}3d_{-2}
electronic configuration is responsible for the properties of the atom. The
transition field strengths are determined. Calculations on the ground state of
the Li+ ion allow us to describe the field-dependent ionization energy of the
Li atom. Some general arguments on the ground states of multi-electron atoms in
strong magnetic fields are provided.Comment: 11 pages, 6 figures, submitted to Physical Review
Fractional Superstrings with Space-Time Critical Dimensions Four and Six
We propose possible new string theories based on local world-sheet symmetries
corresponding to extensions of the Virasoro algebra by fractional spin
currents. They have critical central charges and Minkowski
space-time dimensions for an integer. We present evidence
for their existence by constructing modular invariant partition functions and
the massless particle spectra. The dimension and strings have
space-time supersymmetry.Comment: 9 page
The ground state of the carbon atom in strong magnetic fields
The ground and a few excited states of the carbon atom in external uniform
magnetic fields are calculated by means of our 2D mesh Hartree-Fock method for
field strengths ranging from zero up to 2.35 10^9 T. With increasing field
strength the ground state undergoes six transitions involving seven different
electronic configurations which belong to three groups with different spin
projections S_z=-1,-2,-3. For weak fields the ground state configuration arises
from the field-free 1s^2 2s^2 2p_0 2p_{-1}, S_z=-1 configuration. With
increasing field strength the ground state involves the four S_z=-2
configurations 1s^22s2p_0 2p_{-1}2p_{+1}, 1s^22s2p_0 2p_{-1}3d_{-2}, 1s^22p_0
2p_{-1}3d_{-2}4f_{-3} and 1s^22p_{-1}3d_{-2}4f_{-3}5g_{-4}, followed by the two
fully spin polarized S_z=-3 configurations 1s2p_02p_{-1}3d_{-2}4f_{-3}5g_{-4}
and 1s2p_{-1}3d_{-2}4f_{-3}5g_{-4}6h_{-5}. The last configuration forms the
ground state of the carbon atom in the high field regime \gamma>18.664. The
above series of ground state configurations is extracted from the results of
numerical calculations for more than twenty electronic configurations selected
due to some general energetical arguments.Comment: 6 figures,acc. Phys.Rev.
Electromagnetic dipole moments of charged baryons with bent crystals at the LHC
We propose a unique program of measurements of electric and magnetic dipole
moments of charm, beauty and strange charged baryons at the LHC, based on the
phenomenon of spin precession of channeled particles in bent crystals. Studies
of crystal channeling and spin precession of positively- and negatively-charged
particles are presented, along with feasibility studies and expected
sensitivities for the proposed experiment using a layout based on the LHCb
detector.Comment: 19 pages, 13 figure
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