464,369 research outputs found
The relation between goal adjustment, goal disturbance, and mental well-being among persons with multiple sclerosis
Objective: This study investigated the role of goal adjustment, i.e. disengaging from blocked goals and reengaging into alternative goals, in mental well-being and goal disturbance in persons with multiple sclerosis (MS). Design: A cross-sectional design was used with self-report data from questionnaires and Personal Project Analysis (PPA). Main outcome measures: Dependent variables were mental well-being, indicated by depression/anxiety (HADS; Hospital Anxiety and Depression Scale) and mental functioning (SF-36; Short Form Health Survey), and goal disturbance, indicated by goal manageability and goal interference (PPA). Independent variables were patient-reported physical impairment (SF-36) and goal disengagement and reengagement (GAS; Goal Adjustment Scale). Results: Higher goal reengagement was associated with better mental well-being, but unrelated to goal disturbance. Goal disengagement only showed a negative association with anxiety. High disengagement was associated with lower goal interference but only for those also scoring high on reengagement. Goal adjustment did not buffer the effects of physical impairment on mental well-being and goal disturbance. Contrary to expectations, higher goal reengagement increased the association between physical impairment and goal interference. Conclusion: Although goal reengagement is associated with better mental well-being in persons with MS, it might also strengthen the perceived effect of physical impairment on goal interference
Information-disturbance tradeoff in estimating a maximally entangled state
We derive the amount of information retrieved by a quantum measurement in
estimating an unknown maximally entangled state, along with the pertaining
disturbance on the state itself. The optimal tradeoff between information and
disturbance is obtained, and a corresponding optimal measurement is provided.Comment: 4 pages. Accepted for publication on Physical Review Letter
Forest Stand Structure and Primary Production in relation to Ecosystem Development, Disturbance, and Canopy Composition
Temperate forests are complex ecosystems that sequester carbon (C) in biomass. C storage is related to ecosystem-scale forest structure, changing over succession, disturbance, and with community composition. We quantified ecosystem biological and physical structure in two forest chronosequences varying in disturbance intensity, and three late successional functional types to examine how multiple structural expressions relate to ecosystem C cycling. We quantified C cycling as wood net primary production (NPP), ecosystem structure as Simpsonâs Index, and physical structure as leaf quantity (LAI) and arrangement (rugosity), examining how wood NPP-structure relates to light distribution and use-efficiency. Relationships between structural attributes of biodiversity, LAI, and rugosity differed. Development of rugosity was conserved regardless of disturbance and composition, suggesting optimization of vegetation arrangement over succession. LAI and rugosity showed significant positive productivity trends over succession, particularly within deciduous broadleaf forests, suggesting these measures of structure contain complementary, not redundant, information related to C cycling
Finite-Amplitude Instability of the Compressible Laminar Wake. Strongly Amplified Disturbances
The interaction between mean flow and finiteâamplitude disturbances in certain experimentally observed unstable, compressible laminar wakes is considered theoretically without explicitly assuming small amplification rates. Boundaryâlayer form of the twoâdimensional meanâflow momentum, kinetic energy and thermal energy equations and the timeâaveraged kinetic energy equation of spatially growing disturbances are recast into their respective von KĂĄrmĂĄn integral form which show the overâall physical coupling. The Reynolds shear stresses couple the mean flow and disturbance kinetic energies through the conversion mechanism familiar in lowâspeed flows. Both the mean flow and disturbance kinetic energies are coupled to the meanâflow thermal energy through their respective viscous dissipation. The work done by the disturbance pressure gradients gives rise to an additional coupling between the disturbance kinetic energy and the meanâflow thermal energy. The compressibility transformation suggested by work on turbulent shear flows is not applicable to this problem because of the accompanying ad hoc assumptions about the disturbance behavior. The disturbances of a discrete frequency which corresponds to the most unstable fundamental component, are first evaluated locally. Subsequent meanâflow and disturbance profileâshape assumptions are made in terms of a meanâflowâdensity Howarth variable. The compressibility transformation, which cannot convert this problem into a form identical to the lowâspeed problem of Ko, Kubota, and Lees because of the compressible disturbance quantities, nevertheless, yields a much simplified description of the mean flow
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