25,528 research outputs found
Review Of Interventions For Parental Depression From Toddlerhood To Adolescence
Because of the recurrent course, significant burden, and intergenerational impact of depression, there is a great need for interventions for depressed parents and their children. This article reviews eight interventions that 1) aim to impact the functioning and well-being of 18-month to 18-year old children of depressed parents and 2) have been evaluated in controlled studies. The interventions are described and the empirical evidence of their efficacy is reviewed and critiqued. Existing research points to several promising intervention strategies, such as psychoeducation about parental depression, addressing parenting in adult depression treatment, promoting positive parent-child interactions, and teaching coping skills to children. Common limitations of the research in this area are small sample sizes, homogenous samples, and lack of replication. Implementation problems within the mental healthcare system are highlighted. Multi-component interventions seem to be a promising approach to address the complex impact parental depression has on children and the parent-child relationship. This review illustrates the need for more research on intervention models that can be implemented with children at various developmental levels
A sensitive infrared imaging up converter and spatial coherence of atmospheric propagation
An infrared imaging technique based on the nonlinear interaction known as upconversion was used to obtain images of several astronomical objects in the 10 micrometer spectral region, and to demonstrate quantitatively the sharper images allowed for wavelengths beyond the visible region. The deleterious effects of atmospheric inhomogeneities on telescope resolution were studied in the infrared region using the technique developed. The low quantum efficiency of the device employed severely limited its usefulness as an astronomical detector
Dynamic method to distinguish between left- and right-handed chiral molecules
We study quantum systems with broken symmetry that can be modelled as cyclic
three-level atoms with coexisting one- and two-photon transitions. They can be
selectively optically excited to any state. As an example, we show that left-
and right-handed chiral molecules starting in the same initial states can
evolve into different final states by a purely dynamic transfer process. That
means, left- and right-handed molecules can be distinguished purely
dynamically.Comment: 4 pages, submitted to Phys. Rev.
Two-peaked and flat-top perfect bright solitons in epsilon-near-zero nonlinear metamaterials: novel Kerr self-trapping mechanisms
We analytically investigate transverse magnetic (TM) spatial bright solitons,
as exact solutions of Maxwell's equations, propagating through nonlinear
metamaterials whose linear dielectric permittivity is very close to zero and
whose effective nonlinear Kerr parameters can be tailored to achieve values not
available in standard materials. Exploiting the fact that, in the considered
medium, linear and nonlinear polarization can be comparable at feasible and
realistic optical intensities, we identify two novel self-trapping mechanisms
able to support two-peaked and flat-top solitons, respectively. Specifically,
these two novel mechanisms are based on the occurrence of critical points at
which the effective nonlinear permittivity vanishes, the two mechanisms
differing in the way the compensation between linear and nonlinear polarization
is achieved through the non-standard values of the nonlinear parameters.Comment: 7 pages, 4 figure
Flow pattern transition accompanied with sudden growth of flow resistance in two-dimensional curvilinear viscoelastic flows
We find three types of steady solutions and remarkable flow pattern
transitions between them in a two-dimensional wavy-walled channel for low to
moderate Reynolds (Re) and Weissenberg (Wi) numbers using direct numerical
simulations with spectral element method. The solutions are called
"convective", "transition", and "elastic" in ascending order of Wi. In the
convective region in the Re-Wi parameter space, the convective effect and the
pressure gradient balance on average. As Wi increases, the elastic effect
becomes suddenly comparable and the first transition sets in. Through the
transition, a separation vortex disappears and a jet flow induced close to the
wall by the viscoelasticity moves into the bulk; The viscous drag significantly
drops and the elastic wall friction rises sharply. This transition is caused by
an elastic force in the streamwise direction due to the competition of the
convective and elastic effects. In the transition region, the convective and
elastic effects balance. When the elastic effect dominates the convective
effect, the second transition occurs but it is relatively moderate. The second
one seems to be governed by so-called Weissenberg effect. These transitions are
not sensitive to driving forces. By the scaling analysis, it is shown that the
stress component is proportional to the Reynolds number on the boundary of the
first transition in the Re-Wi space. This scaling coincides well with the
numerical result.Comment: 33pages, 23figures, submitted to Physical Review
Coherent Backscattering of Light with Nonlinear Atomic Scatterers
We study coherent backscattering of a monochromatic laser by a dilute gas of
cold two-level atoms in the weakly nonlinear regime. The nonlinear response of
the atoms results in a modification of both the average field propagation
(nonlinear refractive index) and the scattering events. Using a perturbative
approach, the nonlinear effects arise from inelastic two-photon scattering
processes. We present a detailed diagrammatic derivation of the elastic and
inelastic components of the backscattering signal both for scalar and vectorial
photons. Especially, we show that the coherent backscattering phenomenon
originates in some cases from the interference between three different
scattering amplitudes. This is in marked contrast with the linear regime where
it is due to the interference between two different scattering amplitudes. In
particular we show that, if elastically scattered photons are filtered out from
the photo-detection signal, the nonlinear backscattering enhancement factor
exceeds the linear barrier two, consistently with a three-amplitude
interference effect.Comment: 18 pages, 13 figures, submitted to Phys. Rev.
Spatial and Temporal Hadron Correlators below and above the Chiral Phase Transition
Hadronic correlation functions at finite temperature in QCD, with four
flavours of dynamical quarks, have been analyzed both above and below the
chiral symmetry restoration temperature. We have used both point and extended
sources for spatial as well as temporal correlators. The effect of periodic
temporal boundary conditions for the valence quarks on the spatial meson
correlators has also been investigated. All our results are consistent with the
existence of individual quarks at high temperatures. A measurement of the
residual interaction between the quarks is presented.Comment: 19 pages HLRZ 54/93, BI-TP 93/76, TIFR/TH/94-1
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