2,813 research outputs found
Public health training in Europe. Development of European masters degrees in public health.
BACKGROUND: Changing political and economic relations in Europe mean that there are new challenges for public health and public health training. There have been several attempts to develop training at the master's level in public health which is focused on meeting the new needs. These have failed due to being too inflexible to allow participation by schools of public health. METHODS: A project funded by the European Union involving public health trainers has developed a new approach which allows participating schools to retain their national differences and work within local rules and traditions, but which aims to introduce the European dimension into public health training. This paper reports the conclusions of this project. CONCLUSIONS: A network of schools wishing to develop European Master's degrees is being established and other schools offering good quality programmes will be able to join
Quantum statistics of interacting dimer spin systems
The compound TlCuCl3 represents a model system of dimerized quantum spins with strong interdimer interactions. We investigate the triplet dispersion as a function of temperature by inelastic neutron scattering experiments on single crystals. By comparison with a number of theoretical approaches we demonstrate that the description of Troyer, Tsunetsugu, and Wurtz [Phys. Rev. B 50, 13 515 (1994)] provides an appropriate quantum statistical model for dimer spin systems at finite temperatures, where many-body correlations become particularly important
The Effects of Negative Legacies on the Adjustment of Parentally Bereaved Children and Adolescents
This is a report of a qualitative analysis of a sample of bereaved families in which one parent died and in which children scored in the clinical range on the Child Behavior Check List. The purpose of this analysis was to learn more about the lives of these children. They were considered to be at risk of developing emotional and behavioral problems associated with the death. We discovered that many of these “high risk” children had a continuing bond with the deceased that was primarily negative and troubling for them in contrast to a comparison group of children not at risk from the same study. Five types of legacies, not mutually exclusive, were identified: health related, role related, personal qualities, legacy of blame, and an emotional legacy. Coping behavior on the part of the surviving parent seemed to make a difference in whether or not a legacy was experienced as negative
Magnetic properties of (VO)_2P_2O_7: two-plane structure and spin-phonon interactions
Detailed experiments on single-crystal (VO)_2P_2O_7 continue to reveal new
and unexpected features. We show that a model composed of two, independent
planes of spin chains with frustrated magnetic coupling is consistent with
nuclear magnetic resonance and inelastic neutron scattering measurements. The
pivotal role of PO_4 groups in mediating intrachain exchange interactions
explains both the presence of two chain types and their extreme sensitivity to
certain lattice vibrations, which results in the strong magnetoelastic coupling
observed by light scattering. We compute the respective modifications of the
spin and phonon dynamics due to this coupling, and illustrate their observable
consequences on the phonon frequencies, magnon dispersions, static
susceptibility and specific heat.Comment: 10 pages, 9 figure
Calculation of some determinants using the s-shifted factorial
Several determinants with gamma functions as elements are evaluated. This
kind of determinants are encountered in the computation of the probability
density of the determinant of random matrices. The s-shifted factorial is
defined as a generalization for non-negative integers of the power function,
the rising factorial (or Pochammer's symbol) and the falling factorial. It is a
special case of polynomial sequence of the binomial type studied in
combinatorics theory. In terms of the gamma function, an extension is defined
for negative integers and even complex values. Properties, mainly composition
laws and binomial formulae, are given. They are used to evaluate families of
generalized Vandermonde determinants with s-shifted factorials as elements,
instead of power functions.Comment: 25 pages; added section 5 for some examples of application
Free Thermal Convection Driven by Nonlocal Effects
We report and explain a convective phenomenon observed in molecular dynamics
simulations that cannot be classified either as a hydrodynamics instability nor
as a macroscopically forced convection. Two complementary arguments show that
the velocity field by a thermalizing wall is proportional to the ratio between
the heat flux and the pressure. This prediction is quantitatively corroborated
by our simulations.Comment: RevTex, figures is eps, submited for publicatio
Block orthogonal polynomials: I. Definition and properties
Constrained orthogonal polynomials have been recently introduced in the study
of the Hohenberg-Kohn functional to provide basis functions satisfying particle
number conservation for an expansion of the particle density. More generally,
we define block orthogonal (BO) polynomials which are orthogonal, with respect
to a first Euclidean scalar product, to a given -dimensional subspace of polynomials associated with the constraints. In addition, they are
mutually orthogonal with respect to a second Euclidean scalar product. We
recast the determination of these polynomials into a general problem of finding
particular orthogonal bases in an Euclidean vector space endowed with distinct
scalar products. An explicit two step Gram-Schmidt orthogonalization (G-SO)
procedure to determine these bases is given. By definition, the standard block
orthogonal (SBO) polynomials are associated with a choice of equal
to the subspace of polynomials of degree less than . We investigate their
properties, emphasizing similarities to and differences from the standard
orthogonal polynomials. Applications to classical orthogonal polynomials will
be given in forthcoming papers.Comment: This is a reduced version of the initial manuscript, the number of
pages being reduced from 34 to 2
Buoyant-thermocapillary instabilities of differentially heated liquid layers
URL: http://www-spht.cea.fr/articles/T95/103 Instabilités d'écoulements thermocapillaires en présence de gravitéInternational audienceThe stability of buoyant-thermocapillary-driven flows in a fluid layer subjected to a horizontal temperature gradient is analysed. Our purpose is the modelization of recent experimental results obtained for a fluid of Prandtl number Pr=7, by Daviaud and Vince [Phys. Rev. E, 4432 (1993)] who observed a transition between traveling waves and stationary rolls when the height of fluid is increased. Our model takes into account several effects which were examined separately in previous studies. The relative importance of buoyancy and thermocapillarity is controlled by the ratio W of Marangoni number to Rayleigh number. The fluid layer is bounded below by a rigid plane whose temperature varies linearly along the direction of the thermal gradient. A Biot number is introduced to describe heat transfer at the top free surface. Our stability analysis establishes the existence of a transition between stationary and oscillatory modes when W exceeds a value which is function of the Biot number. Moreover, two types of oscillatory modes have been identified which differ by the range of variation of their critical parameters (wave number, frequency, angle of propagation) versus W
Local spin fluctuations in iron-based superconductors: 77Se and 87Rb NMR measurements of Tl0.47Rb0.34Fe1.63Se2
We report nuclear magnetic resonance (NMR) studies of the intercalated iron
selenide superconductor (Tl, Rb)FeSe ( K).
Single-crystal measurements up to 480 K on both Se and Rb nuclei
show a superconducting phase with no magnetic order. The Knight shifts and
relaxation rates increase very strongly with temperature above ,
before flattening at 400 K. The quadratic -dependence and perfect
proportionality of both and data demonstrate their origin in
paramagnetic moments. A minimal model for this pseudogap-like response is not a
missing density of states but two additive contributions from the itinerant
electronic and local magnetic components, a framework unifying the and
data in many iron-based superconductors
Magnetic Properties of (VO)_2P_2O_7 from Frustrated Interchain Coupling
Neutron-scattering experiments on (VO)_2P_2O_7 reveal both a gapped magnon
dispersion and an unexpected, low-lying second mode. The proximity and
intensity of these modes suggest a frustrated coupling between the alternating
spin chains. We deduce the minimal model containing such a frustration, and
show that it gives an excellent account of the magnon dispersion, static
susceptibility and electron spin resonance absorption. We consider two-magnon
states which bind due to frustration, and demonstrate that these may provide a
consistent explanation for the second mode.Comment: RevTeX, 5 pages, 6 figures, compressed from first versio
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