534 research outputs found
Reconsidering the risk assessment concept: <br>Standardizing the impact description as a building block for vulnerability assessment
Risk assessments for natural hazards are becoming more widely used and accepted. Using an extended definition of risk, it becomes obvious that performant procedures for vulnerability assessments are vital for the success of the risk concept. However, there are large gaps in knowledge about vulnerability. To alleviate the situation, a conceptual extension of the scope of existing and new models is suggested. The basis of the suggested concept is a stadardization of the output of hazard assessments. This is achieved by defining states of the target objects that depend on the impact and at the same time affect the object's performance characteristics. The possible state variables can be related to a limited set of impact descriptors termed generic impact description interface. The concept suggests that both hazard and vulnerability assessment models are developed according to the specification of this interface, thus facilitating modularized risk assessments. Potential problems related to the application of the concept include acceptance issues and the lacking accuracy of transformation of outputs of existing models. Potential applications and simple examples for adapting existing models are briefly discussed
Generation of helical magnetic fields from inflation
The generation of helical magnetic fields during single field inflation due
to an axial coupling of the electromagnetic field to the inflaton is discussed.
We find that such a coupling always leads to a blue spectrum of magnetic fields
during slow roll inflation. Though the helical magnetic fields further evolve
during the inverse cascade in the radiation era after inflation, we conclude
that the magnetic fields generated by such an axial coupling can not lead to
observed field strength on cosmologically relevant scales.Comment: 4 pages, 1 figure; Contribution to the proceedings of the
International Conference on Gravitation and Cosmology (ICGC), Goa, India,
December, 201
Can slow roll inflation induce relevant helical magnetic fields?
We study the generation of helical magnetic fields during single field
inflation induced by an axial coupling of the electromagnetic field to the
inflaton. During slow roll inflation, we find that such a coupling always leads
to a blue spectrum with , as long as the theory is treated
perturbatively. The magnetic energy density at the end of inflation is found to
be typically too small to backreact on the background dynamics of the inflaton.
We also show that a short deviation from slow roll does not result in strong
modifications to the shape of the spectrum. We calculate the evolution of the
correlation length and the field amplitude during the inverse cascade and
viscous damping of the helical magnetic field in the radiation era after
inflation. We conclude that except for low scale inflation with very strong
coupling, the magnetic fields generated by such an axial coupling in single
field slow roll inflation with perturbative coupling to the inflaton are too
weak to provide the seeds for the observed fields in galaxies and clusters.Comment: 33 pages 6 figures; v4 to match the accepted version to appear in
JCA
Follow-up study evaluating the long term outcome of chondromimetic in the treatment of osteochondral defects in the knee
© 2020 by the authors. Scaffolds are thought to be a key element needed for successful cartilage repair treatments, and this prospective extension study aimed to evaluate long-term structural and clinical outcomes following osteochondral defect treatment with a cell-free biphasic scaffold. Structural outcomes were assessed using quantitative 3-D magnetic resonance imaging (MRI) and morphological segmentation to determine the percentage of defect filling and repair cartilage T2 relaxation times, and clinical outcomes were determined with the modified Cincinnati Rating System, and the Knee Injury and Osteoarthritis Outcome Score (KOOS). Seventeen subjects with osteochondral defects in the knee were treated with ChondroMimetic scaffolds, from which 15 returned for long-term evaluation at a mean follow-up of 7.9 - 0.3 years. The defects treated were trochlear donor sites for mosaicplasty in 13 subjects, and medial femoral condyle defects in 2 subjects. MRI analysis of scaffold-treated defects found a mean total defect filling of 95.2 - 3.6%, and a tissue mean T2 relaxation time of 52.5 - 4.8 ms, which was identical to the T2 of ipsilateral control cartilage (52.3 - 9.2 ms). The overall modified Cincinnati Rating System score was statistically significant from baseline (p = 0.0065), and KOOS subscales were equivalent to other cartilage repair techniques. ChondroMimetic treatment resulted in a consistently high degree of osteochondral defect filling with durable, cartilage-like repair tissue at 7.9 years, potentially associated with clinical improvement
Beyond main effects? Affect level as a moderator in the relation between affect dynamics and depressive symptoms
The current study examined the role of mean levels of affect in the relation between affect dynamics and depressive symptoms. We analyzed data from seven studies that measured affect in daily life in adolescents and young adults (N = 1,448, age range = 11.7-29.9 years, 64.8% females). We tested main and interaction effects of affect dynamics (variability and inertia) and affect level on depressive symptoms, separately for positive affect (PA) and negative affect (NA). For PA, we found mostly main, but no interaction effects. Depressive symptoms were associated with more PA variability and less PA inertia, indicating that depressive symptoms in young people may be characterized by more variable and less lingering PA, independent of PA mean levels. For NA, we found a significant moderation effect between NA variability and NA levels for depressive symptoms at baseline. For individuals with low NA levels, high NA variability was associated with more depressive symptoms. In contrast, for individuals with high NA levels, high NA variability was associated with fewer depressive symptoms. These results suggest that the relative adaptiveness of NA variability depends on overall NA levels and underscores the need for a more nuanced understanding of affect variability in depression
Beyond main effects? Affect level as a moderator in the relation between affect dynamics and depressive symptoms
The current study examined the role of mean levels of affect in the relation between affect dynamics and depressive symptoms. We analyzed data from seven studies that measured affect in daily life in adolescents and young adults (N = 1,448, age range = 11.7-29.9 years, 64.8% females). We tested main and interaction effects of affect dynamics (variability and inertia) and affect level on depressive symptoms, separately for positive affect (PA) and negative affect (NA). For PA, we found mostly main, but no interaction effects. Depressive symptoms were associated with more PA variability and less PA inertia, indicating that depressive symptoms in young people may be characterized by more variable and less lingering PA, independent of PA mean levels. For NA, we found a significant moderation effect between NA variability and NA levels for depressive symptoms at baseline. For individuals with low NA levels, high NA variability was associated with more depressive symptoms. In contrast, for individuals with high NA levels, high NA variability was associated with fewer depressive symptoms. These results suggest that the relative adaptiveness of NA variability depends on overall NA levels and underscores the need for a more nuanced understanding of affect variability in depression
Future of the universe in modified gravitational theories: Approaching to the finite-time future singularity
We investigate the future evolution of the dark energy universe in modified
gravities including gravity, string-inspired scalar-Gauss-Bonnet and
modified Gauss-Bonnet ones, and ideal fluid with the inhomogeneous equation of
state (EoS). Modified Friedmann-Robertson-Walker (FRW) dynamics for all these
theories may be presented in universal form by using the effective ideal fluid
with an inhomogeneous EoS without specifying its explicit form. We construct
several examples of the modified gravity which produces accelerating
cosmologies ending at the finite-time future singularity of all four known
types by applying the reconstruction program. Some scenarios to resolve the
finite-time future singularity are presented. Among these scenarios, the most
natural one is related with additional modification of the gravitational action
in the early universe. In addition, late-time cosmology in the non-minimal
Maxwell-Einstein theory is considered. We investigate the forms of the
non-minimal gravitational coupling which generates the finite-time future
singularities and the general conditions for this coupling in order that the
finite-time future singularities cannot emerge. Furthermore, it is shown that
the non-minimal gravitational coupling can remove the finite-time future
singularities or make the singularity stronger (or weaker) in modified gravity.Comment: 25 pages, no figure, title changed, accepted in JCA
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