1,497 research outputs found
On the regularity of the covariance matrix of a discretized scalar field on the sphere
We present a comprehensive study of the regularity of the covariance matrix
of a discretized field on the sphere. In a particular situation, the rank of
the matrix depends on the number of pixels, the number of spherical harmonics,
the symmetries of the pixelization scheme and the presence of a mask. Taking
into account the above mentioned components, we provide analytical expressions
that constrain the rank of the matrix. They are obtained by expanding the
determinant of the covariance matrix as a sum of determinants of matrices made
up of spherical harmonics. We investigate these constraints for five different
pixelizations that have been used in the context of Cosmic Microwave Background
(CMB) data analysis: Cube, Icosahedron, Igloo, GLESP and HEALPix, finding that,
at least in the considered cases, the HEALPix pixelization tends to provide a
covariance matrix with a rank closer to the maximum expected theoretical value
than the other pixelizations. The effect of the propagation of numerical errors
in the regularity of the covariance matrix is also studied for different
computational precisions, as well as the effect of adding a certain level of
noise in order to regularize the matrix. In addition, we investigate the
application of the previous results to a particular example that requires the
inversion of the covariance matrix: the estimation of the CMB temperature power
spectrum through the Quadratic Maximum Likelihood algorithm. Finally, some
general considerations in order to achieve a regular covariance matrix are also
presented.Comment: 36 pages, 12 figures; minor changes in the text, matches published
versio
Distribution of Visual and Oculomotor Alterations in a Clinical Population of Children with and without Neurodevelopmental Disorders
A prospective, non-randomized comparative study was conducted to compare the distribution of oculomotor and visual alterations in children with neurodevelopmental disorders and healthy children without such disorders. Sixty-nine children (aged 6–13 years) were enrolled and divided into three groups: a control group (CG) of 23 healthy children; a group of 18 healthy children with oculomotor abnormalities (OAG); and a group of 28 children with a neurodevelopmental disorder (NDDG), with 15 cases of dyslexia, 7 cases of developmental coordination disorder (DCD) and 6 cases of attention deficit/hyperactivity disorder (ADHD). Significantly worse near stereopsis was found in NDDG compared with CG (p < 0.001) and OAG (p = 0.001). Likewise, a significantly lower amplitude of accommodation was found in NDDG compared with CG in both the right (p = 0.001) and left eyes (p < 0.001). No statistically significant differences between groups were found in the measurement of near and distance phoria (p ≥ 0.557), near point of convergence (p = 0.700) and fusional vergences (p ≥ 0.059). Significantly impaired oculomotor test scores were found in NDDG compared with CG (p < 0.001), with no significant differences between OAG and NDDG (p ≥ 0.063). The comparison between the three types of neurodevelopmental disorders included revealed the presence of a significantly lower amplitude of accommodation in children with DCD compared with dyslexics. Furthermore, less exophoria at near was present in children with dyslexia compared with children with ADHD (p = 0.018) and DCD (p = 0.054). In conclusion, children with dyslexia, ADHD and DCD show an altered oculomotor pattern and a more reduced amplitude of accommodation, not always compatible with the diagnostic criteria of an accommodative insufficiency. Accommodative and binocular vision problems are not always present in these children and cannot be considered an etiologic factor.The author David P. Piñero has received funding from the Ministry of Economy, Industry and Competitiveness of Spain within the program Ramón y Cajal, RYC-2016-20471
Large scale physical modeling synthesis, parallel computing, and musical experimentation:The NESS Project
Influence of the temperature and 2,5-dimethylfuran concentration on its sooting tendency
The sooting tendency of 2,5-dimethylfuran (2,5-DMF), as a proposed fuel or fuel additive, has been studied in a flow reactor at different reaction temperatures (975, 1075, 1175, 1275, 1375, and 1475 K) and inlet 2,5-DMF concentrations (5000, 7500, and 15,000 ppm) under pyrolytic conditions. The quantification of soot and light gases has been done. Additionally, the experimental results of the light gases have been simulated with a detailed gas-phase chemical kinetic model. The experimental results indicate that the temperature has a great influence on both the soot and gas yields, as well as on the concentration of the light gases of pyrolysis. The inlet 2,5-DMF con- centration influences the soot yield, whereas no significant effect is observed on the gas yield
Countering Home-Grown Terrorists in Australia: An Overview of Legislation, Policy and Actors Since 2001
This article explores the impact of counter-terrorism legislation and policy in Australia. In particular it explores how legislation facilitated prosecution and conviction of persons involved in home-grown terrorism, including analysis of investigation and prosecution policy surrounding the ul-Haque and Haneef cases. Particular attention is given to the terrorism trials involving Benbrika & Ors and Elomar & Ors. What makes these trials intriguing is the fact that most of those convicted could be more easily described as more vulnerable than menacing. Sentencing of those convicted was cognate with no policies for rehabilitation. The small number of convictions under the legislation when considered against the increased funding of counter-terrorism, loss of traditional rights and privileges and Australia’s involvement in Afghanistan and Iraq raises issues about adequate policy setting in this area
Recommendations for reporting ion mobility Mass Spectrometry measurements
Here we present a guide to ion mobility mass spectrometry experiments, which covers both linear and nonlinear methods: what is measured, how the measurements are done, and how to report the results, including the uncertainties of mobility and collision cross section values. The guide aims to clarify some possibly confusing concepts, and the reporting recommendations should help researchers, authors and reviewers to contribute comprehensive reports, so that the ion mobility data can be reused more confidently. Starting from the concept of the definition of the measurand, we emphasize that (i) mobility values (K0) depend intrinsically on ion structure, the nature of the bath gas, temperature, and E/N; (ii) ion mobility does not measure molecular surfaces directly, but collision cross section (CCS) values are derived from mobility values using a physical model; (iii) methods relying on calibration are empirical (and thus may provide method‐dependent results) only if the gas nature, temperature or E/N cannot match those of the primary method. Our analysis highlights the urgency of a community effort toward establishing primary standards and reference materials for ion mobility, and provides recommendations to do so. © 2019 The Authors. Mass Spectrometry Reviews Published by Wiley Periodicals, Inc
Multinet : enabler for next generation enterprise wireless services
Wireless communications are currently experiencing a fast migration toward the beyond third-generation (B3G)/fourth generation (4G) era. This represents a generational change in wireless systems: new capabilities related to mobility and new services support is required and new concepts as individual-centric, user-centric or ambient-aware communications are included. One of the main restrictions associated to wireless technology is mobility management, this feature was not considered in the design phase; for this reason, a complete solution is not already found, although different solutions are proposed and are being proposed. In MULTINET project, features as mobility and multihoming are applied to wireless network to provide the necessary network and application functionality enhancements for seamless data communication mobility considering end-user scenario and preferences. The aim of this paper is to show the benefits of these functionalities from the Service Providers and final User point of view
Caracterización y manejo de una disfunción oculomotora: a propósito de un caso
Un niño de 11 años derivado de la Unidad Infantil por pérdidas de fijación en la lectura, saltos de línea, un control anómalo de los saltos de palabra, lectura lenta y dolores de cabeza al final del día, para una valoración de la visión binocular acomodativa y oculomotora. Tras esta valoración se encuentra una disfunción oculomotora y se procede a evaluar y hacer el seguimiento mediante Eye Tracking y el software Clinical Eye Tracker que permite analizar la oculomotricidad en lectura y mediante estímulos visuales determinados y programados previamente. En este caso se analiza la eficacia de la subjetividad en las diferentes pruebas que valoran la oculomotricidad
On the combination of multi-cloud and network coding for cost-efficient storage in industrial applications
The adoption of both Cyber–Physical Systems (CPSs) and the Internet-of-Things (IoT) has
enabled the evolution towards the so-called Industry 4.0. These technologies, together with cloud
computing and artificial intelligence, foster new business opportunities. Besides, several industrial
applications need immediate decision making and fog computing is emerging as a promising solution
to address such requirement. In order to achieve a cost-efficient system, we propose taking advantage
from spot instances, a new service offered by cloud providers, which provide resources at lower prices.
The main downside of these instances is that they do not ensure service continuity and they might
suffer from interruptions. An architecture that combines fog and multi-cloud deployments along with
Network Coding (NC) techniques, guarantees the needed fault-tolerance for the cloud environment,
and also reduces the required amount of redundant data to provide reliable services. In this paper
we analyze how NC can actually help to reduce the storage cost and improve the resource efficiency
for industrial applications, based on a multi-cloud infrastructure. The cost analysis has been carried
out using both real AWS EC2 spot instance prices and, to complement them, prices obtained from
a model based on a finite Markov chain, derived from real measurements. We have analyzed the
overall system cost, depending on different parameters, showing that configurations that seek to
minimize the storage yield a higher cost reduction, due to the strong impact of storage cost
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