1,736 research outputs found
Fast electrochemical doping due to front instability in organic semiconductors
The electrochemical doping transformation in organic semiconductor devices is
studied in application to light-emitting cells. It is shown that the device
performance can be significantly improved by utilizing new fundamental
properties of the doping process. We obtain an instability, which distorts the
doping fronts and increases the doping rate considerably. We explain the
physical mechanism of the instability, develop theory, provide experimental
evidence, and perform numerical simulations. We further show how improved
device design can amplify the instability thus leading to a much faster doping
process and device kinetics.Comment: 4 pages, 4 figure
Inter-Intra Molecular Dynamics as an Iterated Function System
The dynamics of units (molecules) with slowly relaxing internal states is
studied as an iterated function system (IFS) for the situation common in e.g.
biological systems where these units are subjected to frequent collisional
interactions. It is found that an increase in the collision frequency leads to
successive discrete states that can be analyzed as partial steps to form a
Cantor set. By considering the interactions among the units, a self-consistent
IFS is derived, which leads to the formation and stabilization of multiple such
discrete states. The relevance of the results to dynamical multiple states in
biomolecules in crowded conditions is discussed.Comment: 7 pages, 7 figures. submitted to Europhysics Letter
Survival and residence times in disordered chains with bias
We present a unified framework for first-passage time and residence time of
random walks in finite one-dimensional disordered biased systems. The
derivation is based on exact expansion of the backward master equation in
cumulants. The dependence on initial condition, system size, and bias strength
is explicitly studied for models with weak and strong disorder. Application to
thermally activated processes is also developed.Comment: 13 pages with 2 figures, RevTeX4; v2:minor grammatical changes, typos
correcte
Augmented Reality for People with Visual Impairments: Designing and Creating Audio-Tactile Content from Existing Objects
ISBN: 978-3-319-94273-5International audienceTactile maps and diagrams are widely used as accessible graphical media for people with visual impairments, in particular in the context of education. They can be made interactive by augmenting them with audio feedback. It is however complicated to create audio-tactile graphics that have rich and realistic tactile textures. To overcome these limitations, we propose a new augmented reality approach allowing novices to easily and quickly augment real objects with audio feedback. In our user study, six teachers created their own audio-augmentation of objects, such as a botanical atlas, within 30 minutes or less. Teachers found the tool easy to use and were confident about re-using it. The resulting augmented objects allow two modes: exploration mode provides feedback on demand about an element, while quiz mode provides questions and answers. We evaluated the resulting audio-tactile material with five visually impaired children. Participants found the resulting interactive graphics exciting to use independently of their mental imagery skills
Exploring the links between star formation and minor companions around isolated galaxies
Previous studies have shown that galaxies with minor companions exhibit an
elevated star formation rate. We reverse this inquiry, constructing a
volume-limited sample of \simL\star (Mr \leq -19.5 + 5 log h) galaxies from the
Sloan Digital Sky Survey that are isolated with respect to other luminous
galaxies. Cosmological simulations suggest that 99.8% of these galaxies are
alone in their dark matter haloes with respect to other luminous galaxies. We
search the area around these galaxies for photometric companions. Matching
strongly star forming (EW(H{\alpha})\geq 35 \AA) and quiescent (EW(H{\alpha})<
35 \AA) samples for stellar mass and redshift using a Monte Carlo resampling
technique, we demonstrate that rapidly star-forming galaxies are more likely to
have photometric companions than other galaxies. The effect is relatively
small; about 11% of quiescent, isolated galaxies have minor photometric
companions at radii \leq 60 kpc h kpc while about 16% of strongly
star-forming ones do. Though small, the cumulative difference in satellite
counts between strongly star-forming and quiescent galaxies is highly
statistically significant (PKS = 1.350 \times10) out to to radii of \sim
100 h kpc. We discuss explanations for this excess, including the
possibility that \sim 5% of strongly star-forming galaxies have star formation
that is causally related to the presence of a minor companion.Comment: 7 pages, 6 figures, submitted to MNRA
Synchronization of active mechanical oscillators by an inertial load
Motivated by the operation of myogenic (self-oscillatory) insect flight
muscle, we study a model consisting of a large number of identical oscillatory
contractile elements joined in a chain, whose end is attached to a damped
mass-spring oscillator. When the inertial load is small, the serial coupling
favors an antisynchronous state in which the extension of one oscillator is
compensated by the contraction of another, in order to preserve the total
length. However, a sufficiently massive load can sychronize the oscillators and
can even induce oscillation in situations where isolated elements would be
stable. The system has a complex phase diagram displaying quiescent,
synchronous and antisynchrononous phases, as well as an unsual asynchronous
phase in which the total length of the chain oscillates at a different
frequency from the individual active elements.Comment: 5 pages, 4 figures, To appear in Phys. Rev. Let
Discapacidad visual y orientación urbana. Estudio piloto sobre planos táctiles producidos en Impresión 3D
[EN] This article presents a pilot study conducted in Barcelona with blind and visually-impaired people. The aim was to
analyze the use and efficacy of tactile maps produced by means of 3D printing. For this purpose, structured interviews were
used, along with direct observation, the creation of cognitive maps and tasks with prototypes. The aim has been to examine
the instrumental and communicative value of these products in terms of interpreting, memorizing and understanding a
certain urban route, comparing this with experience in situ, focusing on the difficulties faced by the visually disabled when
visiting new places. Findings show the utility of this type of technique in aiding visually disabled users to memorize routes.
As a limitation, this study shows that tactile maps are not wholly efficient since they require verbal support, which makes
it hard for them to be used autonomously.[ES] El trabajo aquà expuesto presenta un estudio piloto llevado a cabo en Barcelona con personas invidentes y deficientes
visuales. El objetivo del mismo ha sido analizar el uso y la eficacia de los planos táctiles producidos mediante Impresión en
3D. Para ello se han empleado entrevistas estructuradas, observación directa, realización de mapas cognitivos y tareas con
prototipos. De esta manera se ha tratado deprofundizar en elvalor instrumentalycomunicativo de estosproductos a la hora
de interpretar, memorizar y comprender un determinado recorrido urbano, contrastándolo con la experiencia in situ, atendiendo a las dificultades que este tipo de personas presentan a la hora de visitar nuevos lugares. Los resultados obtenidos
demuestran la utilidad de este tipo de técnica para memorizar recorridos por parte de este tipo de usuarios. Como limitación,
el estudio muestra que los planos táctiles no resultan del todo eficientes pues precisan de apoyo verbal, hecho que dificulta su
uso autónomo.This research has been funded by the Spanish Ministry of Science and Innovation as part of the National Fundamental Research Programme, the National R&D/Innovation Plan, within the project “Study and design of
orientation elements, communication support and other accessories to improve accessibility in different spheres of interpreting natural and/or built heritage’ (DPI2008-03981/DPI). The authors would also like particularly to thank the following for their selfless collaboration: the ONCE Educational Resources Centre in Barcelona and staff from the Disabled Service Programme at the Universitat Politècnica de Catalunya. The study was also carried out as part of the Research Staff Mobility Programme at Universitat Jaume I (E-2010-32) funded by the Caixa Castelló-Bancaixa Foundation.Gual OrtÃ, J.; Puyuelo Cazorla, M.; Lloveras, J.; Merino Sanjuan, L. (2012). Visual Impairment and urban orientation. Pilot study with tactile maps produced through 3D Printing. Psyecology. 3(2):239-250. https://doi.org/10.1174/217119712800337747S2392503
Biochemistry and functional aspects of human glandular kallikreins
Human urinary kallikrein was purified by gel filtration on Sephacryl S-200 and affinity chromatography on aprotinin-Sepharose, followed by ion exchange chromatography on DEAE-Sepharose. In dodecylsulfate gel electrophoresis two protein bands with molecular weights of 41,000 and 34,000 were separated. The amino acid composition and the carbohydrate content of the kallikrein preparation were determined; isoleucine was identified as the only aminoterminal amino acid. The bimolecular velocity constant for the inhibition by diisopropyl fluorophosphate was determined as 9±2 l mol–1 min–1. The hydrolysis of a number of substrates was investigated and AcPheArgOEt was found to be the most sensitive substrate for human urinary kallikrein. Using this substrate an assay method for kallikrein in human urine was developed.
It was shown by radioimmunoassay that pig pancreatic kallikrein can be absorbed in the rat intestinal tract. Furthermore, in dogs the renal excretion of glandular kallikrein from blood was demonstrated by radioimmunological methods
The fitness of African malaria vectors in the presence and limitation of host behaviour
<p>Background
Host responses are important sources of selection upon the host species range of ectoparasites and phytophagous insects. However little is known about the role of host responses in defining the host species range of malaria vectors. This study aimed to estimate the relative importance of host behaviour to the feeding success and fitness of African malaria vectors, and assess its ability to predict their known host species preferences in nature.</p>
<p>Methods
Paired evaluations of the feeding success and fitness of African vectors Anopheles arabiensis and Anopheles gambiae s.s in the presence and limitation of host behaviour were conducted in a semi-field system (SFS) at Ifakara Health Institute, Tanzania. In one set of trials, mosquitoes were released within the SFS and allowed to forage overnight on a host that was free to exhibit natural behaviour in response to insect biting. In the other, mosquitoes were allowed to feed directly on from the skin surface of immobile hosts. The feeding success and subsequent fitness of vectors under these conditions were investigated on 6 host types (humans, calves, chickens, cows, dogs and goats) to assess whether physical movements of preferred host species (cattle for An. arabiensis, humans for An. gambiae s.s.) were less effective at preventing mosquito bites than those of common alternatives.</p>
<p>Results
Anopheles arabiensis generally had greater feeding success when applied directly to host skin than when foraging on unrestricted hosts (in five of six host species). However, An. gambiae s.s obtained blood meals from free and restrained hosts with similar success from most host types (four out of six). Overall, the blood meal size, oviposition rate, fecundity and post-feeding survival of mosquito vectors were significantly higher after feeding on hosts free to exhibit behaviour, than those who were immobilized during feeding trials.</p>
<p>Conclusions
Allowing hosts to move freely during exposure to mosquitoes was associated with moderate reductions in mosquito feeding success, but no detrimental impact to the subsequent fitness of mosquitoes that were able to feed upon them. This suggests that physical defensive behaviours exhibited by common host species including humans do not impose substantial fitness costs on African malaria vectors.</p>
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