4,011 research outputs found
Thermionic research and development program Final report
Rhenium electrode material investigation and performance studies of low temperature cesium vapor thermionic converter
The psychological impact of stillbirth on women: a systematic review.
This systematic review explored the psychological impact of stillbirth (from
20 weeks gestation) on mothers. A search was conducted in the National
Library for Health and Web of Science, Cochrane Review, and Google
Scholar. A secondary search based on results from the preliminary search was
undertaken. A systematic search identified 26 articles (8 qualitative, 18
quantitative studies), which met criteria and were reviewed according to
guidelines. The findings revealed that stillbirth is a distressing experience that
can result in high levels of psychological symptoms including anxiety,
depression, distress, and negative well-being. Symptoms appear to be highest
in the first few months post loss although there is evidence to suggest that for
some, symptoms may persist up to 3 years. The long-lasting impact of
stillbirth on women was echoed in the qualitative research. Risk factors for
higher levels of anxious and depressive symptoms included higher parity at
the time of loss and not being married. Social support in particular was
identified to be beneficial for women post loss. Longitudinal studies utilizing
designs which permit causality to be determined are required to explore the
specific experience of stillbirth. Further exploration of risk and protective
factors, cultural beliefs, and the impact on partner relationships is needed.
Clinical implications of the findings are discussed in light of current guidance
Can we use medical examiners' records for suicide surveillance and prevention research in Nova Scotia?
Introduction: Medical examiners' records can contribute to our understanding of the extent of suicide in a population, as well as associated sociodemographic and other factors
Family food environments of 5-6 year-old-children: does socioeconomic status make a difference?
Analytical Estimate of the Critical Velocity for Vortex Pair Creation in Trapped Bose Condensates
We use a modified Thomas-Fermi approximation to estimate analytically the
critical velocity for the formation of vortices in harmonically trapped BEC. We
compare this analytical estimate to numerical calculations and to recent
experiments on trapped alkali condensates.Comment: 12 page
A simple scheme for allocating capital in a foreign exchange proprietary trading firm
We present a model of capital allocation in a foreign exchange proprietary trading firm. The owner allocates capital to individual traders, who operate within strict risk limits. Traders specialize in individual currencies, but are given discretion over their choice of trading rule. The owner provides the simple formula that determines position sizes – a formula that does not require estimation of the firm-level covariance matrix. We provide supporting empirical evidence of excess risk-adjusted returns to the firm-level portfolio, and we discuss a modification of the model in which the owner dictates the choice of trading rule
Concentration Dependence of the Effective Mass of He-3 Atoms in He-3/He-4 Mixtures
Recent measurements by Yorozu et al. (S. Yorozu, H. Fukuyama, and H.
Ishimoto, Phys. Rev. B 48, 9660 (1993)) as well as by Simons and Mueller (R.
Simons and R. M. Mueller, Czhechoslowak Journal of Physics Suppl. 46, 201
(1976)) have determined the effective mass of He-3 atoms in a He-3/He-4 mixture
with great accuracy. We here report theoretical calculations for the dependence
of that effective mass on the He-3 concentration. Using correlated basis
functions perturbation theory to infinite order to compute effective
interactions in the appropriate channels, we obtain good agreement between
theory and experiment.Comment: 4 pages, 1 figur
Optical properties of carbon nanofiber photonic crystals
Carbon nanofibers (CNF) are used as components of planar photonic crystals.
Square and rectangular lattices and random patterns of vertically aligned CNF
were fabricated and their properties studied using ellipsometry. We show that
detailed information such as symmetry directions and the band structure of
these novel materials can be extracted from considerations of the polarization
state in the specular beam. The refractive index of the individual nanofibers
was found to be n_CNF = 4.1.Comment: 10 pages, 4 figure
Single Particle and Fermi Liquid Properties of He-3/--He-4 Mixtures: A Microscopic Analysis
We calculate microscopically the properties of the dilute He-3 component in a
He-3/--He-4 mixture. These depend on both, the dominant interaction between the
impurity atom and the background, and the Fermi liquid contribution due to the
interaction between the constituents of the He-3 component. We first calculate
the dynamic structure function of a He-3 impurity atom moving in He-3. From
that we obtain the excitation spectrum and the momentum dependent effective
mass. The pole strength of this excitation mode is strongly reduced from the
free particle value in agreement with experiments; part of the strength is
distributed over high frequency excitations. Above k > 1.7^{-1}$ the
motion of the impurity is damped due to the decay into a roton and a low energy
impurity mode. Next we determine the Fermi--Liquid interaction between He-4
atoms and calculate the pressure-- and concentration dependence of the
effective mass, magnetic susceptibility, and the He-3--He-3 scattering phase
shifts. The calculations are based on a dynamic theory that uses, as input,
effective interactions provided by the Fermi hypernetted--chain theory. The
relationship between both theories is discussed. Our theoretical effective
masses agree well with recent measurements by Yorozu et al. (Phys. Rev. B 48,
9660 (1993)) as well as those by R. Simons and R. M. Mueller (Czekoslowak
Journal of Physics Suppl. 46, 201 (1996)), but our analysis suggests a new
extrapolation to the zero-concentration limit. With that effective mass we also
find a good agreement with the measured Landau parameter F_0^a.Comment: 47 pages, 15 figure
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