Many polymer networks and gels display nanostructural heterogeneity in the form of spatially inhomogeneous crosslinking densities, along with additional topological defects such as dangling chain ...ends, crosslinker-crosslinker shortcuts, and chains forming loops. In this review, we summarize and interrelate existing studies on the origin of this heterogeneity and on its characterization by scattering techniques, microscopies, and NMR spectroscopy. We also outline some recent investigations on the impact of polymer-network nanostructural heterogeneity on the elasticity, swelling, and permeability of polymer gels.
Many polymer gels display network defects and crosslinking inhomogeneity. This review reflects and interrelates investigations on the characterization of such polymer-network heterogeneity and on its impact on the swelling, elasticity, and permeability of polymer gels.
This study addressed the question of whether the next generation of neurologists want to become ‘interventional neurologists’ and perform endovascular therapy in acute ischaemic stroke. Responses ...were received from 1218 neurology trainees out of 27 European countries. In total, 568 (47%) stated that they would want to be an interventional neurologist.
Background and purpose
Endovascular therapy (EVT) has become standard care for acute ischaemic stroke caused by large‐vessel occlusion in the anterior circulation. However, access to this treatment in Europe remains poor. The lack of operators is a contributing factor and there is on‐going discussion as to whether other specialists, including neurologists, could contribute to the EVT workforce. The question remains whether the next generation of neurologists want to become ‘interventional neurologists’. The aim of this study was to address this question.
Methods
We conducted a short survey within the National Representatives Network (a division of the Resident and Research Fellow Section, European Academy of Neurology) in order to determine the interest of future neurologists in performing EVT.
Results
A total of 1218 responses from 27 European countries were received, with some variation in the number of respondents and results among individual countries. In total, 568 neurology trainees (47%) stated that they would want to be an ‘interventional neurologist’.
Conclusion
Our findings suggest that neurologists could make a significant contribution to the workforce performing EVT and have important implications for the development and uptake of training programmes in Europe.
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•Opuntia ficus-indica (OPU) extract was loaded within PEG- crosslinked chitosan films.•The prepared films showed swelling and vapor transmission rate suitable as wound dressings.•At a ...given composition, the Young’s modulus of films is close to that of human skin.•Release of OPU was higher from films at low OPU load.•Low OPU content films showed the best tissue repairing activity.
In the present study, chitosan-based wound dressings loaded with the extract of Opuntia ficus-indica (OPU) were prepared. OPU is known for its capability to accelerate skin injury repair. Chitosan (Ch) was crosslinked with a low molecular weight diepoxy-poly(ethylene glycol) (diePEG), and hydrogel films with different Ch/PEG composition and OPU content were prepared by casting. The occurrence of crosslinking reaction was confirmed by FTIR spectroscopy. FTIR and DSC analysis suggested that ionic interactions occur between chitosan and OPU. Tensile tests evidenced that the crosslinking caused a decrease of Young’s modulus, which approaches the value of the human skin modulus. Swelling characteristics, water vapor transmission rate, and release kinetics demonstrated that these films are adequate for the proposed application. Finally, a scratch test on a keratinocytes monolayer showed that the rate of cell migration in the presence of OPU-loaded samples is about 3-fold higher compared to unloaded films, confirming the repairing activity of OPU.
Learning of new skills may occur through Hebbian associative changes in the synaptic strength of cortical connections spike-timing-dependent plasticity (STDP), but how the precise temporal ...relationship of the presynaptic and postsynaptic inputs determines the STDP effects in humans is poorly understood. We used a novel paired associative stimulation protocol to repeatedly activate the short-latency connection between the posterior parietal cortex and the primary motor cortex (M1) of the left-dominant hemisphere. In different experiments, we systematically varied the temporal relationships between the stimuli and the preferential activation of different M1 neuronal populations by applying transcranial magnetic stimulation over M1 with different coil orientations and in different states of cortical excitability (rest vs muscular contraction). We found evidence for the existence of both Hebbian and anti-Hebbian STDP in human long-range connections. The induction of bidirectional long-term potentiation or depression in M1 depended not only on the relative timing between the stimuli but, crucially, on the stimulation of specific neuronal populations and the activity state of the cortex. Our findings demonstrate that these mechanisms are not fixed but susceptible to rapid adaptations. This sudden transition from anti-Hebbian to Hebbian plasticity likely involves local dynamics of interaction with different populations of postsynaptic neurons.
Cloud measurements are usually carried out with airborne campaigns, which are expensive and are limited by temporal duration and weather conditions. Ground-based measurements at high-altitude ...research stations therefore play a complementary role in cloud study. Using the meteorological data (wind speed, direction, temperature, humidity, visibility, etc.) collected by the German Weather Service (DWD) from 2000 to 2012 and turbulence measurements recorded by multiple ultrasonic sensors (sampled at 10 Hz) in 2010, we show that the Umweltforschungsstation Schneefernerhaus (UFS) located just below the peak of Zugspitze in the German Alps, at a height of 2650 m, is a well-suited station for cloud–turbulence research. The wind at UFS is dominantly in the east–west direction and nearly horizontal. During the summertime (July and August) the UFS is immersed in warm clouds about 25 % of the time. The clouds are either from convection originating in the valley in the east, or associated with synoptic-scale weather systems typically advected from the west. Air turbulence, as measured from the second- and third-order velocity structure functions that exhibit well-developed inertial ranges, possesses Taylor microscale Reynolds numbers up to 104, with the most probable value at ~ 3000. In spite of the complex topography, the turbulence appears to be nearly as isotropic as many laboratory flows when evaluated on the "Lumley triangle".
Beam Formation Studies on the CERN IS03b H Source Lettry, J; Vnuchenko, A; Bertolo, S ...
Journal of physics. Conference series,
04/2022, Letnik:
2244, Številka:
1
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
Abstract
An H
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ion source is being operated at the new 160 MeV linear injector (Linac4) of the CERN accelerator complex. The source’s plasma is of the Radio Frequency Inductively Coupled Plasma type ...(RF-ICP), without magnetic cusp and runs with Cs-loss compensation 1. Vertical downward oriented filter- and electron dump-dipolar magnetic fields expand over the plasma chamber, beam-formation, beam-extraction and electron dump regions and generate horizontal asymmetry and beam angular deflection partially compensated by mechanical alignment of the front-end. The H
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beam is generated via volume and caesiated plasma surface modes, the latter inducing a radial asymmetry characterized by an increased current density close to the plasma electrode surface 2. Asymmetries affecting the meniscus shape, or its current density have to be simulated via 3D Particle In Cell Monte Carlo (PIC-MC) solvers, such as the Orsay Negative Ion eXtraction code (ONIX) 3. Validation of these simulations require dedicated measurements. This contribution describes experimental methods newly implemented at CERN’s ion source test stand and initial results for Optical and Beam Emission Spectroscopy (OES, BES), emittance and beam profile measurements. In a later stage, the gathered data sets can be compared to source plasma parameters and extracted beam parameters from PIC-MC simulations, once coupled to the Ion Beam Simulation (IBSimu) 4 beam transport code. The experimental parameter space includes RF-power, density of neutrals, position of the RF coil and extraction field. Beams of H
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, D
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and protons were produced; examples of measured data are presented in this contribution.
Dosimetric measurements of the hard X-ray emission by a small-chamber 4.7kJ Mather-type plasma focus device capable of producing neat radiographs of metallic objects, were carried out with a set of ...thermoluminescent detectors TLD 700 (LiF:Mg,Ti). Measurements of the hard X-ray dose dependence with the angular position relative to the electrodes axis, are presented. The source-detector distance was changed in the range from 50 to 100cm, and the angular positions were explored between ± 70°, relative to the symmetry axis of the electrodes. On-axis measurements show that the X-ray intensity is uniform within a half aperture angle of 6°, in which the source delivers an average dose of (1.5 ± 0.1)mGy/sr per shot. Monte Carlo calculations suggest that the energy of the electron beam responsible for the X-ray emission ranges 100–600keV.
•The angular dependence of the x-ray dose of a plasma focus is measured.•The average dose resulted 1.5mGy/sr per shot.•A narrow beam of small aperture angle was experimentally determined.•Monte Carlo calculations suggest energies of the associated electrons of 100–600keV.
Ensuring that people at risk of overdosing on opioids have easy access to naloxone is an essential part of the fight against the opioid crisis. This study evaluates the impact of the 2016 California ...law (CA AB1535) permitting pharmacies to dispense this life-saving medication without a physician's prescription.
California counties were categorized on the basis of population density (rural, suburban, urban), rate of opioid-related deaths by population density (high, medium, low), and rate of opioid prescriptions by population density (high, medium, low). Ten diverse pharmacies from each category were selected for inclusion. In a brief 1-minute interview conducted between July and August 2021, pharmacists from 146 California pharmacies were surveyed regarding their knowledge of CA AB1535, their practice of dispensing naloxone without a physician's prescription, and whether they normally stock naloxone. Chi-square tests were used to compare responses.
Although almost all pharmacies interviewed (94%) were aware of the law and most of them (64%) dispensed naloxone without a physician's prescription, few statistically significant differences were found between surveyed categories. There were no significant relationships between naloxone availability at pharmacies and overdose death rates.
Our results suggest that the number of California pharmacies dispensing naloxone without a physician's prescription has continued to increase since the implementation of CA AB1535. However, despite increased access to naloxone at pharmacies, opioid overdose rates have continued to rise since 2016, indicating the need for a multifaceted harm reduction approach.
•California pharmacies can dispense naloxone without a physician's prescription.•A total of 64% of surveyed pharmacies dispensed naloxone without a prescription.•Despite increased access to naloxone at pharmacies, overdose rates continue to rise.•There was no relationship between naloxone availability and overdose death rates.•Dispensing of naloxone was similar across rural, suburban, and urban counties.
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