4,870 research outputs found
A neural mechanism for binaural pitch perception via ghost stochastic resonance
We present a physiologically plausible binaural mechanism for the perception
of the pitch of complex sounds via ghost stochastic resonance. In this scheme,
two neurons are driven by noise and different periodic signal each (with
frequencies f1=kf0 and f2=(k+1)f0, where k>1), and their outputs (plus noise)
are applied synaptically to a third neuron. Our numerical results, using the
Morris-Lecar neuron model with chemical synapses explicity considered, show
that intermediate noise levels enhance the response of the third neuron at
frequencies close to f0, as in the cases previously described of ghost
resonance. For the case of inharmonic combinations of inputs (both frequencies
shifted by the same amount Df) noise is also seen to enhance the response of
the third neuron at a frequency fr with also shift linearly with Df. In
addition, we show that similar resonances can be observed as a function of the
synaptic time constant. The suggested ghost-resonance-based stochastic
mechanism can thus arise either at the peripheral level or at a higher level of
neural processing in the perception of the pitchComment: 7 pages, 5 figure
Effective transport properties
Porous media are an integral part of electrochemical energy conversion and storage devices, including fuel cells, electrolyzers, redox flow batteries and lithium-ion batteries, among others. The calculation of effective transport properties is required for designing more efficient components and for closing the formulation of macroscopic continuum models at the cell/stack level. In this chapter, OpenFOAM is used to determine the effective transport properties of virtually-generated fibrous gas diffusion layers. The analysis focuses on effective properties that rely on the fluid phase, diffusivity and permeability, which are determined by solving Laplace and Navier-Stokes equations at the pore scale, respectively. The model implementation (geometry generation, meshing, solver settings and postprocessing) is described, accompanied by a discussion of the main results. The dependence of orthotropic effective transport properties on porosity is examined and compared with traditional correlations.This work was supported by the projects PID2019-106740RB-I00 and EIN2020-112247 (Spanish Agencia Estatal de Investigación) and the project PEM4ENERGY-CM-UC3M funded by the call "Programa de apoyo a la realización de proyectos interdisciplinares de I+D para jóvenes investigadores de la Universidad Carlos III de Madrid 2019-2020" under the frame of the "Convenio Plurianual Comunidad de Madrid-Universidad Carlos III de Madrid"
Effect of thickness and outlet area fraction of macroporous gas diffusion layers on oxygen transport resistance in water injection simulations
Enhanced water removal through the gas diffusion layer (GDL) is important for the design of high-performance proton exchange fuel cells. In this work, the effects of GDL thickness and open area fraction at the GDL/flow field interface are examined under water invasion for a carbon-paper GDL (similar to Toray TGP-H series). Both uncompressed and inhomogeneously compressed samples are considered. Transport in heterogeneous, macroporous GDLs is modeled by means of a hybrid 3D discrete/continuum formulation based on a subdivision of the porous medium into control volumes due to the lack of a well-defined separation between pore and layer scales. Capillary-dominated transport of liquid water is simulated with an invasion percolation algorithm, while oxygen diffusion is simulated with a continuum formulation. Model predictions are validated with previous numerical and experimental data. It is shown that the combination of thin GDLs (thickness∼100μm
) and high GDL/flow field open area fractions can facilitate water removal/oxygen supply from/to the catalyst layer and can provide a more uniform oxygen distribution over large cell active areas. In agreement with previous work, porous flow fields with pore sizes comparable to the GDL thickness are good candidates to meet the above requirements, while improving water removal from the flow field (higher gas-phase velocity than conventional millimeter-sized channels) and ensuring a more uniform assembly compression.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This work was supported by the projects PID2019-106740RB-I00 and EIN2020-112247 (Spanish Agencia Estatal de Investigación)
Fifteen years follow-up of photorefractive keratectomy up to 10 D of myopia: outcomes and analysis of the refractive regression
PURPOSE:
To evaluate outcomes of photorefractive keratectomy up to -10.00 D of myopia and -4.50 of astigmatism and to develop a predictive model for the refractive changes in the long term.
SETTING:
Vissum Corporation and Miguel Hernandez University (Alicante, Spain).
DESIGN:
Retrospective-prospective observational series of cases.
METHODS:
This study included 33 eyes of 33 patients aged 46.79±7.04 years (range 40-57) operated with the VISX 20/20 excimer laser with optical zones of 6 mm. No mitomycin C was used in any of these cases. The minimum follow-up was 15 years. The main outcome measures were: uncorrected and corrected distance visual acuity, manifest refraction and corneal topography. Linear regression models were developed from the observed refractive changes over time.
RESULTS:
Safety and efficacy indexes at 15 years were 1.18 and 0.83, respectively. No statistically significant differences were detected for any keratometric variable during the follow-up (p≥0.103). 15 years after the surgery 54.55% of the eyes were within ±1.00 D of spherical equivalent and 84.85% within ±2.00 D. The uncorrected distance visual acuity at 15 years was 20/25 or better in 60.6% of the eyes and 20/40 or better in 72.73% of the eyes. The correlation between the attempted and the achieved refractions was r=0.948 (p<0.001) at 1 year, and r=0.821 (p<0.001) at 15 years. No corneal ectasia was detected in any case during the follow-up.
CONCLUSIONS:
Photorefractive keratectomy is a safe refractive procedure in the long term within the range of myopia currently considered suitable for its use, although its efficacy decreases with time, especially, in high myopia. The model developed predicts a myopic regression of 2.00 D at 15 years for an ablation depth of 130 µm
The economic geography of football success: empirical evidence from european cities
Introduction. – 1. The geography of successful football teams: an analytical framework – 2. Empirical analysis – 2.1. Data, model estimation and results – 2.2. Cities and teams: some remarks about market size and teams’ performance – 3. Conclusions – 4. Annex
The production process in basketball: Empirical evidence from Spanish league
The main objective of this paper is to provide an empirical assessment of the production process in a basketball team. We estimate a logit model in which the output produced by a team is the game outcome (win or loss) and the inputs are those play characteristics that impact on that outcome. From the results obtained it is clear that, on average, there is a substantial difference between the impact of each play characteristic on a basketball team’s winning probability and that probability varies as the quality/quantity of the inputs used changes, albeit not proportionally.sports economics, team sport, professional basketball, productive process, logit model
A bibliometric study of the research area of videogames using Dimensions.ai database
Videogames are a very interesting area of research for fields as diverse as computer science, health, psychology or even social sciences. Every year a growing number of articles are published in different topics inside this field, so it is very convenient to study the different bibliometric data in order to consolidate the research efforts.
Thus, the aim of this work is to conduct a study on the distribution of articles related to videogames in the different fields of research, as well as to measure their interest over time, to identify the sources, countries and authors with the highest scientific production. In order to carry out this analysis, the information system Dimensions.ai has been considered, since it covers a large number of documents and allows for easy downloading and analysis of datasets.
According to the study, three countries are the most prolific in this area: USA, Canada and UK. The obtained results also indicate that the fields with the highest number of publications are Information and Computer Sciences, Medical and Health Sciences, and Psychology and Cognitive Sciences, in this order. With regard to the impact of the publications, differences between the number of citations, and the number of Altmetric Attention Score, have been found
Identifying habitation patterns in world heritage areas through social media and open datasets
Although cities with World Heritage (WH) areas worldwide are
socially active, specific social and cultural complexities are
associated primarily with the abandonment and decay of districts.
Contemporary habitation patterns in historic districts require
technology to understand parallel realities in protected areas.
This stakeholders-based approach benefits significantly from
cross-referencing locative social media and open data sources.
Therefore, the concepts put forward in this paper use evidence
from an empirical case of WH areas in selected Spanish urban
sites. The cartographic correlation of data identifies hotspots of
activities and coldspots around services within each site. The
results present two significant findings. The first confirms the
successful implementation of a digital method to support current
transitions for the historic city. The second demonstrates that
social networks and open datasets can mirror contemporary
social interaction in historic cities. Finally, the study calls on
further investigating Artificial Intelligence-based assessments for
the future of WH areas
The Heritagization of a Mediterranean Vernacular Mountain Landscape: Concepts, Problems and Processes
The concepts of heritage and landscape have always changed or been developed
based on the social context of the time. For decades, attempts have been made to
find a pragmatic definition for a changing setting where values, evolve or
disappear in step with the changing ways and styles of life of each society.
Heritage and landscape have inherent values such as identity, culture, authenticity
or integrity, that is to say, landscape character. Current heritagization processes
that lead to an understanding of the palimpsest of landscape and heritage layers
need to be participatory and inclusive as their importance and sustainability
depend on this. This article shows how the early stages of a heritagization process
unfold in a small region of the western Mediterranean, Penyagolosa (Castellón).
The current problems of the region - depopulation, abandonment and loss of
culture and identity - are assessed in search of an understanding and appreciation
of a heritage landscape. The research uses techniques such as photo elicitation in
a workshops, GIS analysis and evaluates the different options to characterize the
landscape offered by different researchers. The analysis explains the different
phases of the research to establish the basis of the heritagization of this setting.
The study also established a parallel perspective for valorization between
researchers and local population - objective and subjective visions - thus
encouraging the interest of the social majority linked to the landscape
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