322 research outputs found
Enhancement of rare-earth--transition-metal exchange interaction in PrFe probed by inelastic neutron scattering
The fundamental magnetic interactions of PrFe are studied by
inelastic neutron scattering and anisotropy field measurements. Data analysis
confirms the presence of three magnetically inequivalent sites, and reveals an
exceptionally large value of the exchange field. The unexpected importance of
-mixing effects in the description of the ground-state properties of
PrFe is evidenced, and possible applications of related compounds
are envisaged.Comment: 4 RevTeX pages, 4 EPS figures. Accepted for publication by Appl.
Phys. Lett. (will be found at http://apl.aip.org
Multiagency safeguarding arrangements during and beyond the Covid-19 pandemic: identifying shared learning
Measures to combat transmission of the coronavirus presented unprecedented challenges for safeguarding and child protection practice, including through withdrawal of routine opportunities to observe and engage with children and families and disruption of systems for inter-agency communication and coordination. This article reports on a two-stage study designed to identify shared learning from adaptations to professional practice in response to the measures. Interviews with 67 London-based senior safeguarding leads from seven professional groups undertaken during the summer of 2020 informed an England-wide survey to similar groups in February–March 2021. SPSS was used to analyse 417 responses, which were supplemented by answers to open questions. Findings are reported using the six practice themes which the Child Safeguarding Practice Review Panel expects to inform shared learning to improve safeguarding at national and local levels. The study revealed the formidable barriers facing professionals in understanding the changing environments in which children were living and in identifying and assessing new or altered risks due to the pandemic; steps taken to respond to changing risks and to keep in touch and re-engage families; strategies to support critical thinking and challenge among professionals working under unprecedented pressure; and opportunities for enhanced multiagency working and inter-agency collaboration
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Cellular Hydraulics Suggests a Poroelastic Cytoplasm Rheology
The cytoplasm represents the largest part of the cell by volume and hence its rheology sets the rate at which cellular shape change can occur. Recent experimental evidence suggests that cytoplasmic rheology can be described using a poroelastic formulation in which the cytoplasm is considered a biphasic material constituted of a porous elastic solid meshwork (cytoskeleton, organelles, macromolecules) bathed in an interstitial fluid (cytosol). In this picture, the rate of cellular deformation is limited by the rate at which intracellular water can redistribute within the cytoplasm. Though this is a conceptually attractive model, direct supporting evidence has been lacking. Here we present such evidence and directly validate this concept to explain cellular rheology at physiologically relevant time-scales using microindentation tests in conjunction with mechanical, chemical and genetic treatments. Our results show that water redistribution through the solid phase of cytoplasm (cytoskeleton and crowders) plays a fundamental role in setting cellular rheology.Engineering and Applied Science
Direct Evidence of Multi-Bubble Sonoluminescence using Therapeutic Ultrasound and Microbubbles
The
intense conditions generated in the core of a collapsing bubble
have been the subject of intense scrutiny from fields as diverse as
marine biology and nuclear fusion. In particular, the phenomenon of
sonoluminescence, whereby a collapsing bubble emits light, has received
significant attention. Sonoluminescence has been associated predominantly
with millimeter-sized bubbles excited at low frequencies and under
conditions far removed from those associated with the use of ultrasound
in medicine. In this study, however, we demonstrate that sonoluminescence
is produced under medically relevant exposure conditions by microbubbles
commonly used as contrast agents for ultrasound imaging. This provides
a mechanistic explanation for the somewhat controversial reports of
“sonodynamic” therapy, in which light-sensitive drugs
have been shown to be activated by ultrasound-induced cavitation.
To illustrate this, we demonstrate the activation of a photodynamic
therapy agent using microbubbles and ultrasound. Since ultrasound
can be accurately focused at large tissue depths, this opens up the
potential for generating light at locations that cannot be reached
by external sources. This could be exploited both for diagnostic and
therapeutic applications, significantly increasing the range of applications
that are currently restricted by the limited penetration of light
in the tissue
The effects of nonlinear wave propagation on the stability of inertial cavitation
In the context of forecasting temperature and pressure fields in
high-intensity focussed ultrasound, the accuracy of predictive models is
critical for the safety and efficacy of treatment. In such fields inertial
cavitation is often observed. Classically, estimations of cavitation thresholds
have been based on the assumption that the incident wave at the surface of a
bubble was the same as in the far-field, neglecting the effect of nonlinear
wave propagation. By modelling the incident wave as a solution to Burgers'
equation using weak shock theory, the effects of nonlinear wave propagation on
inertial cavitation are investigated using both numerical and analytical
techniques. From radius-time curves for a single bubble, it is observed that
there is a reduction in the maximum size of a bubble undergoing inertial
cavitation and that the inertial collapse occurs earlier in contrast with the
classical case. Corresponding stability thresholds for a bubble whose initial
radius is slightly below the critical Blake radius are calculated. Bifurcation
diagrams and frequency-response curves are presented associated with the loss
of stability. The consequences and physical implications of the results are
discussed with respect to the classical results.Comment: 13 pages, 5 figures, submitted to J. Phys. Conf. Se
Achirality in the low temperature structure and lattice modes of tris(acetylacetonate)iron(iii)
Tris(acetylacteonate) iron(III) is a relatively ubiquitous mononuclear inorganic coordination complex. The bidentate nature of the three acetylacteonate ligands coordinating around a single centre inevitably leads to structural isomeric forms, however whether or not this relates to chirality in the solid state has been questioned in the literature. Variable temperature neutron diffraction data down to T = 3 K, highlights the dynamic nature of the ligand environment, including the motions of the hydrogen atoms. The Fourier transform of the molecular dynamics simulation based on the experimentally determined structure was shown to closely reproduce the low temperature vibrational density of states obtained using inelastic neutron scattering
The cytoplasm of living cells behaves as a poroelastic material
The cytoplasm is the largest part of the cell by volume and hence its rheology sets the rate at which cellular shape changes can occur. Recent experimental evidence suggests that cytoplasmic rheology can be described by a poroelastic model, in which the cytoplasm is treated as a biphasic material consisting of a porous elastic solid meshwork (cytoskeleton, organelles, macromolecules) bathed in an interstitial fluid (cytosol). In this picture, the rate of cellular deformation is limited by the rate at which intracellular water can redistribute within the cytoplasm. However, direct supporting evidence for the model is lacking. Here we directly validate the poroelastic model to explain cellular rheology at physiologically relevant timescales using microindentation tests in conjunction with mechanical, chemical and genetic treatments. Our results show that water redistribution through the solid phase of the cytoplasm (cytoskeleton and macromolecular crowders) plays a fundamental role in setting cellular rheology
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Basic Psychological Need Satisfaction, Recovery State, and Recovery Timing
This study aimed to provide insight into recovery from work-related load effects by examining (1) whether basic psychological need satisfaction (BPN satisfaction) during non-work days facilitates recovery; (2) whether the effect of BPN satisfaction is stronger in case of an unfavorable initial recovery state; and (3) whether the association between BPN satisfaction and recovery is stronger on non-work weekend days compared to nonwork weekdays. Data were collected across seven consecutive days from 205 employees (39% shift workers). Fatigue and depressed mood were assessed as indicators of (failed) recovery. Multilevel analyses revealed that BPN satisfaction during non-work days was related to improved recovery state. This association was stronger if employees had experienced elevated fatigue on the preceding day, and on non-work weekend days compared to non-work weekdays
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