29 research outputs found
Mass hierarchy, mass gap and corrections to Newton's law on thick branes with Poincare symmetry
We consider a scalar thick brane configuration arising in a 5D theory of
gravity coupled to a self-interacting scalar field in a Riemannian manifold. We
start from known classical solutions of the corresponding field equations and
elaborate on the physics of the transverse traceless modes of linear
fluctuations of the classical background, which obey a Schroedinger-like
equation. We further consider two special cases in which this equation can be
solved analytically for any massive mode with m^2>0, in contrast with numerical
approaches, allowing us to study in closed form the massive spectrum of
Kaluza-Klein (KK) excitations and to compute the corrections to Newton's law in
the thin brane limit. In the first case we consider a solution with a mass gap
in the spectrum of KK fluctuations with two bound states - the massless 4D
graviton free of tachyonic instabilities and a massive KK excitation - as well
as a tower of continuous massive KK modes which obey a Legendre equation. The
mass gap is defined by the inverse of the brane thickness, allowing us to get
rid of the potentially dangerous multiplicity of arbitrarily light KK modes. It
is shown that due to this lucky circumstance, the solution of the mass
hierarchy problem is much simpler and transparent than in the (thin)
Randall-Sundrum (RS) two-brane configuration. In the second case we present a
smooth version of the RS model with a single massless bound state, which
accounts for the 4D graviton, and a sector of continuous fluctuation modes with
no mass gap, which obey a confluent Heun equation in the Ince limit. (The
latter seems to have physical applications for the first time within braneworld
models). For this solution the mass hierarchy problem is solved as in the
Lykken-Randall model and the model is completely free of naked singularities.Comment: 25 pages in latex, no figures, content changed, corrections to
Newton's law included for smooth version of RS model and an author adde
Measurement of Family-centered care perception and parental stress in a neonatal unit
ABSTRACT Objective: to evaluate the effects of the implementation of the Patient and Family-Centered Care Model on parents and healthcare perceptions and parental stress. Method: a quasi-experimental study developed in a neonatal unit of a university hospital in the municipality of SĂŁo Paulo, Brazil, with the implementation of this model of care. Data collection were performed by two sample groups, one using non-equivalent groups of parents, and another using equivalent groups of healthcare professionals. The instruments Perceptions of Family-Centered Care-Parent Brazilian Version, Perceptions of Family-Centered Care-Staff Brazilian Version and Parental Stress Scale: Neonatal Intensive Care Unit, were applied to 132 parents of newborns hospitalized and to 57 professionals. Results: there was a statistically significant improvement in the perceptions of the parents in most items assessed (p ≤0,05) and for the staff in relation to the family welcome in the neonatal unit (p = 0.041) and to the comprehension of the family's experience with the infant´s hospitalization (p = 0,050). There was a reduction in the average scores of parental stress, with a greater decrease in the Alteration in Parental Role from 4,2 to 3,8 (p = 0,048). Conclusion: the interventions improved the perceptions of parents and healthcare team related to patient and family-centered care and contributed to reducing parental stress