826 research outputs found
Electric-field induced shape transition of nematic tactoids
The occurrence of new textures of liquid crystals is an important factor in
tuning their optical and photonics properties. Here, we show, both
experimentally and by numerical computation, that under an electric field
chitin tactoids (i.e. nematic droplets) can stretch to aspect ratios of more
than 15, leading to a transition from a spindle-like to a cigar-like shape. We
argue that the large extensions occur because the elastic contribution to the
free energy is dominated by the anchoring. We demonstrate that the elongation
involves hydrodynamic flow and is reversible, the tactoids return to their
original shapes upon removing the field.Comment: 8 pages, 6 figures; accepted for publication in Physical Review
In search of the behavioral effects of fear: A paradigm to assess conditioned suppression in humans
In search of the behavioral effects of fear: A paradigm to assess conditioned suppression in humans
Two-dimensional, blue phase tactoids
We use full nematohydrodynamic simulations to study the statics and dynamics
of monolayers of cholesteric liquid crystals. Using chirality and temperature
as control parameters we show that we can recover the two-dimensional blue
phases recently observed in chiral nematics, where hexagonal lattices of
half-skyrmion topological excitations are interleaved by lattices of trefoil
topological defects. Furthermore, we characterise the transient dynamics during
the quench from isotropic to blue phase. We then proceed by confining
cholesteric stripes and blue phases within finite-sized tactoids and show that
it is possible to access a wealth of reconfigurable droplet shapes including
disk-like, elongated, and star-shaped morphologies. Our results demonstrate a
potential for constructing controllable, stable structures of liquid crystals
by constraining 2D blue phases and varying the chirality, surface tension and
elastic constants.Comment: 13 pages, 5 figures, Molecular Physics, Frenkel Special Issue (2018
Evaporation Through a Dry Soil Layer: Column Experiments
Modeling of water vapor transport through a dry soil layer (DSL), typically formed in the top soil during dry seasons in arid and semi-arid areas, is still problematic. Previous laboratory experiments in controlled environments showed that the only vapor transport process through the DSL is by Fick's law of diffusion. However, field experiments exhibited consistently higher evaporation rates than predicted by diffusion flow only. Some proposed reasons for the mismatch were: (a) daily cycles of condensation and evaporation in the DSL due to changes in solar radiation; (b) wind effects on air movement in the DSL; (c) atmospheric pressure fluctuations; (d) nonlinear influence of the DSL thickness on the evaporation process. To link the laboratory experiments with field observations, we performed soil column experiments in the laboratory with thick (>50 cm) DSL, and with different wind speeds, two radiative lamp schedules (continuous and 12 h daily cycles) and different thicknesses of DSL. Atmospheric pressure, air temperature and humidity were measured continuously. The results show that the evaporation rates observed are larger than those predicted by diffusion flow only. We found that it was possible to model the evaporation rates as a function of atmospheric pressure fluctuations. In conclusion, atmospheric pressure fluctuations can induce evaporation rates in DSL larger than estimated by diffusion flow only, possibly explaining the discrepancy between laboratory and field evaporation rates
Self-reported disability and handicap after hearing-aid fitting and benefit of hearing aids: comparison of fitting procedures, degree of hearing loss, experience with hearing aids and uni- and bilateral fittings
The role of functional health literacy in long-term treatment outcomes in psychosocial care for adolescents
Although among adolescents with psychosocial problems low health literacy may increase the risk of poor treatment outcomes, the contributing mechanisms within treatment remain unclear. A better understanding of these mechanisms could contribute to improved treatment processes and outcomes. This study aims to examine the relationship between functional health literacy, treatment processes (treatment adherence, learning processes), and treatment outcome (level of psychosocial problems) in adolescents in psychosocial care. We used data from a prospective cohort study among adolescents aged 12-18 (N = 390), collected in four successive measurements: at entry into care, and 3, 12, and 24 months thereafter. We used a mixed effect model to investigate the association between level of functional health literacy (adequate vs. inadequate) and treatment processes (treatment adherence, learning processes) and treatment outcome (level of psychosocial problems). Between adolescents with adequate and inadequate functional health literacy, we found no differences or change over time in adherence or learning processes. The level of psychosocial problems significantly declined over time (β = - 1.70, 95% CI [- 2.72, - 0.69], p = .001) to a similar degree in both groups, though, in all measurements, the level was consistently higher for adolescents with inadequate health literacy. We conclude that health literacy levels did not affect change in treatment processes nor in outcomes of psychosocial treatment. However, the consistently higher level of psychosocial problems among adolescents with inadequate health literacy suggests an unaddressed need in psychosocial care
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