7,320 research outputs found
A randomized controlled pilot trial of classroom-based mindfulness meditation compared to an active control condition in sixth-grade children
The current study is a pilot trial to examine the effects of a nonelective, classroom-based, teacher-implemented, mindfulness meditation intervention on standard clinical measures of mental health and affect in middle school children. A total of 101 healthy sixth-grade students (55 boys, 46 girls) were randomized to either an Asian history course with daily mindfulness meditation practice (intervention group) or an African history course with a matched experiential activity (active control group). Self-reported measures included the Youth Self Report (YSR), a modified Spielberger State-Trait Anxiety Inventory, and the Cognitive and Affective Mindfulness Measure –Revised. Both groups decreased significantly on clinical syndrome subscales and affect but did not differ in the extent of their improvements. Meditators were significantly less likely to develop suicidal ideation or thoughts of self-harm than controls. These results suggest that mindfulness training may yield both unique and non-specific benefits that are shared by other novel activities
Gender Differences in Response to a School-Based Mindfulness Training Intervention for Early Adolescents
Mindfulness training has been used to improve emotional wellbeing in early adolescents. However, little is known about treatment outcome moderators, or individual differences that may differentially impact responses to treatment. The current study focused on gender as a potential moderator for affective outcomes in response to school-based mindfulness training. Sixth grade students (N = 100) were randomly assigned to either the six weeks of mindfulness meditation or the active control group as part of a history class curriculum. Participants in the mindfulness meditation group completed short mindfulness meditation sessions four to five times per week, in addition to didactic instruction (Asian history). The control group received matched experiential activity in addition to didactic instruction (African history) from the same teacher with no meditation component. Self-reported measures of emotional wellbeing/affect, mindfulness, and self-compassion were obtained at pre and post intervention. Meditators reported greater improvement in emotional wellbeing compared to those in the control group. Importantly, gender differences were detected, such that female meditators reported greater increases in positive affect compared to females in the control group, whereas male meditators and control males displayed equivalent gains. Uniquely among females but not males, increases in self-reported self-compassion were associated with improvements in affect. These findings support the efficacy of school-based mindfulness interventions, and interventions tailored to accommodate distinct developmental needs of female and male adolescents
Spatial synchronization and extinction of species under external forcing
We study the interplay between synchronization and extinction of a species.
Using a general model we show that under a common external forcing, the species
with a quadratic saturation term in the population dynamics first undergoes
spatial synchronization and then extinction, thereby avoiding the rescue
effect. This is because the saturation term reduces the synchronization time
scale but not the extinction time scale. The effect can be observed even when
the external forcing acts only on some locations provided there is a
synchronizing term in the dynamics. Absence of the quadratic saturation term
can help the species to avoid extinction.Comment: 4 pages, 2 figure
Homoclinic chaos and energy condition violation
In this letter we discuss the connection between so-called homoclinic chaos
and the violation of energy conditions in locally rotationally symmetric
Bianchi type IX models, where the matter is assumed to be non-tilted dust and a
positive cosmological constant. We show that homoclinic chaos in these models
is an artifact of unphysical assumptions: it requires that there exist
solutions with positive matter energy density that evolve through the
singularity and beyond as solutions with negative matter energy density
. Homoclinic chaos is absent when it is assumed that the dust particles
always retain their positive mass.In addition, we discuss more general models:
for solutions that are not locally rotionally symmetric we demonstrate that the
construction of extensions through the singularity, which is required for
homoclinic chaos, is not possible in general.Comment: 4 pages, RevTe
Spontaneous periodic travelling waves in oscillatory systems with cross-diffusion
We identify a new type of pattern formation in spatially distributed active
systems. We simulate one-dimensional two-component systems with predator-prey
local interaction and pursuit-evasion taxis between the components. In a
sufficiently large domain, spatially uniform oscillations in such systems are
unstable with respect to small perturbations. This instability, through a
transient regime appearing as spontanous focal sources, leads to establishment
of periodic traveling waves. The traveling waves regime is established even if
boundary conditions do not favor such solutions. The stable wavelength are
within a range bounded both from above and from below, and this range does not
coincide with instability bands of the spatially uniform oscillations.Comment: 7 pages, 4 figures, as accepted to Phys Rev E 2009/10/2
Analytical Investigation of Innovation Dynamics Considering Stochasticity in the Evaluation of Fitness
We investigate a selection-mutation model for the dynamics of technological
innovation,a special case of reaction-diffusion equations. Although mutations
are assumed to increase the variety of technologies, not their average success
("fitness"), they are an essential prerequisite for innovation. Together with a
selection of above-average technologies due to imitation behavior, they are the
"driving force" for the continuous increase in fitness. We will give analytical
solutions for the probability distribution of technologies for special cases
and in the limit of large times.
The selection dynamics is modelled by a "proportional imitation" of better
technologies. However, the assessment of a technology's fitness may be
imperfect and, therefore, vary stochastically. We will derive conditions, under
which wrong assessment of fitness can accelerate the innovation dynamics, as it
has been found in some surprising numerical investigations.Comment: For related work see http://www.helbing.or
Trapped-ion probing of light-induced charging effects on dielectrics
We use a string of confined Ca ions to measure perturbations to a
trapping potential which are caused by light-induced charging of an
anti-reflection coated window and of insulating patches on the ion-trap
electrodes. The electric fields induced at the ions' position are characterised
as a function of distance to the dielectric, and as a function of the incident
optical power and wavelength. The measurement of the ion-string position is
sensitive to as few as elementary charges per on the
dielectric at distances of order millimetres, and perturbations are observed
for illumination with light of wavelengths as long as 729\,nm. This has
important implications for the future of miniaturised ion-trap experiments,
notably with regards to the choice of electrode material, and the optics that
must be integrated in the vicinity of the ion. The method presented can be
readily applied to the investigation of charging effects beyond the context of
ion trap experiments.Comment: 11 pages, 5 figure
Data on a new beta titanium alloy system reinforced with superlattice intermetallic precipitates
The data presented in this article are related to the research article entitled “a new beta titanium alloy system reinforced with superlattice intermetallic precipitates” (Knowles et al., 2018) [1]. This includes data from the as-cast alloy obtained using scanning electron microscopy (SEM) and x-ray diffraction (XRD) as well as SEM data in the solution heat treated condition. Transmission electron microscopy (TEM) selected area diffraction patterns (SADPs) are included from the alloy in the solution heat treated condition, as well as the aged condition that contained < 100 nm B2 TiFe precipitates [1], the latter of which was found to exhibit double diffraction owing to the precipitate and matrix channels being of a similar width to the foil thickness (Williams and Carter, 2009) [2]. Further details are provided on the macroscopic compression testing of small scale cylinders. Of the micropillar deformation experiment performed in [1], SEM micrographs of focused ion beam (FIB) prepared 2 µm micropillars are presented alongside those obtained at the end of the in-situ SEM deformation as well as videos of the in-situ deformation. Further, a table is included that lists the Schmidt factors of all the possible slip systems given the crystal orientations and loading axis of the deformed micropillars in the solution heat treated and aged conditions
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