3,561 research outputs found
Distribution functions for a family of axially symmetric galaxy models
We present the derivation of distribution functions for the first four
members of a family of disks, previously obtained in (MNRAS, 371, 1873, 2006),
which represent a family of axially symmetric galaxy models with finite radius
and well behaved surface mass density. In order to do this we employ several
approaches that have been developed starting from the potential-density pair
and, essentially using the method introduced by Kalnajs (Ap. J., 205, 751,
1976) we obtain some distribution functions that depend on the Jacobi integral.
Now, as this method demands that the mass density can be properly expressed as
a function of the gravitational potential, we can do this only for the first
four discs of the family. We also find another kind of distribution functions
by starting with the even part of the previous distribution functions and using
the maximum entropy principle in order to find the odd part and so a new
distribution function, as it was pointed out by Dejonghe (Phys. Rep., 133, 217,
1986). The result is a wide variety of equilibrium states corresponding to
several self-consistent finite flat galaxy models.Comment: 12 pages, 7 figures, updated version, accepted for publication in
Rev. Acad. Colomb. Cienc. Ex. Fis. Na
A Bayesian Solution to the Behrens-Fisher problem
A simple solution to the Behrens–Fisher problem based on Bayes factors is presented, and its relation with the Behrens–Fisher distribution is explored. The construction of the Bayes factor is based on a simple hierarchical model, and has a closed form based on the densities of general Behrens–Fisher distributions. Simple asymptotic approximations of the Bayes factor, which are functions of the Kullback–Leibler divergence between normal distributions, are given, and it is also proved to be consistent. Some examples and comparisons are also presented.Open access funding provided by Universidad de Málaga/CBUA
The architectural culture of the Eurasian Mediterranean region: a testimony of satisfactory design for urban infrastructures (May 2014)
The purpose of this paper is to expose the importance of observing cultural systems present in a territory as a reference for the design of urban infrastructures in the new cities and regions of rapid development. If we accept the idea that architecture is an instrument or cultural system developed by man to act as an intermediary to the environment, it is necessary to understand the elemental interaction between man and his environment to meet a satisfactory design.To illustrate this purpose, we present the case of the Eurasian Mediterranean region, where the architectural culture acts as a cultural system of adaptation to the environment and it is formed by an ancient process of selection. From simple observation of architectural types, construction systems and environmental mechanisms treasured in mediterranean historical heritage we can extract crucial information about this elemental interaction.Mediterranean architectural culture has environmental mechanisms responding to the needs of basics habitability, ethnics and passive conditioning. These mechanisms can be basis of an innovative design without compromising the diversity and lifestyles of human groups in the region. The main fundament of our investigation is the determination of the historical heritage of domestic architecture as holder of the formation process of these mechanisms.The result allows us to affirm that the successful introduction of new urban infrastructures in an area need a reliable reference and it must be a cultural system that entailing in essence the environmental conditioning of human existence. The urban infrastructures must be sustainable, understood and accepted by the inhabitants. The last condition is more important when the urban infrastructures are implemented in areas that are developing rapidly or when there is no architectural culture
A bayesian approach for one-way ANOVA under unequal variances
In this report a Bayesian solution to the problem of testing the equality of the means of k independent normal populations with unknown and arbitrary variances is provided. An important issue in the solution of this problem is the determination of groups with equal means, often solved by multiple comparisons, which can lead to results that are difficult to interpret. In order to avoid this drawback, we propose to treat all possible alternatives existing in the alternative hypothesis by considering the set of all possible configurations of the set of k means. This idea is closely related to the statistical pro-blem of cluster analysis. This allows us to reformulate the testing problem in terms of model selection. A hierarchical model is proposed to compute the Bayes factor of all models, as well as the posterior probability of all the possible configurations. Some illustrative examples of the goodness of the proposed solution are presented.Universidad de Málaga. Campus de Excelencia Internacional AndalucĂa Tech
Does the Pulvinar-Lp Complex Contribute to Motor Programming?
[Abstract] Extracellular unit recording studies in the pulvinar lateral posterior complex (Pui-LP) of behaving monkeys have shown a response property not previously reported. In monkeys performing aimed arm reaching movements towards frontally located targets some cells showed a change in activity beginning 495 ± 84 ms before the onset of the reaching movement. This change in frequency precedes that observed in primary motor and parietal posterior cortex for reaching movements. These findings seem to indicate the involvement of the Pul-LP in motor functions and suggest its possible contribution to motor programming.Comisión Asesora de Investigacion Cientifica y Tecnica (España); PR83-210
Optimal energy management for a residential microgrid including a vehicle-to-grid system
An optimization model is proposed to manage a
residential microgrid including a charging spot with a vehicle-togrid
system and renewable energy sources. In order to achieve a
realistic and convenient management, we take into account: (1)
the household load split into three different profiles depending
on the characteristics of the elements considered; (2) a realistic
approach to owner behavior by introducing the novel concept of
range anxiety; (3) the vehicle battery management considering
the mobility profile of the owner and (4) different domestic
renewable energy sources. We consider the microgrid operated
in grid-connected mode. The model is executed one-day-ahead
and generates a schedule for all components of the microgrid.
The results obtained show daily costs in the range of 2.82eto
3.33e; the proximity of these values to the actual energy costs
for Spanish households validate the modeling. The experimental
results of applying the designed managing strategies show daily
costs savings of nearly 10%.Postprint (author’s final draft
Organ-Dedicated Molecular Imaging Systems
[EN] In this review, we will cover both clinical and technical aspects of the advantages and disadvantages of organ specific (dedicated) molecular imaging (MI) systems, namely positron emission tomography (PET) and single photon emission computed tomography, including gamma cameras. This review will start with the introduction to the organ-dedicated MI systems. Thereafter, we will describe the differences and their advantages/disadvantages when compared with the standard large size scanners. We will review time evolution of dedicated systems, from first attempts to current scanners, and the ones that ended in clinical use. We will review later the state of the art of these systems for different organs, namely: breast, brain, heart, and prostate. We will also present the advantages offered by these systems as a function of the special application or field, such as in surgery, therapy assistance and assessment, etc. Their technological evolution will be introduced for each organ-based imager. Some of the advantages of dedicated devices are: higher sensitivity by placing the detectors closer to the organ, improved spatial resolution, better image contrast recovery (by reducing the noise from other organs), and also lower cost. Designing a complete ring-shaped dedicated PET scanner is sometimes difficult and limited angle tomography systems are preferable as they have more flexibility in placing the detectors around the body/organ. Examples of these geometries will be presented for breast, prostate and heart imaging. Recently achievable excellent time of flight capabilities below 300-ps full width at half of the maximum reduce significantly the impact of missing angles on the reconstructed images.This work was supported in part by the European Research Council through the European Union's Horizon 2020 Research and Innovation Program under Grant 695536, in part by the EU through the FP7 Program under Grant 603002, and in part by the Spanish Ministerio de Economia, Industria y Competitividad through PROSPET (DTS15/00152) funded by the Ministerio de Economia y Competitividad under Grant TEC2016-79884-C2-1-R.González MartĂnez, AJ.; Sánchez, F.; Benlloch Baviera, JM. (2018). Organ-Dedicated Molecular Imaging Systems. IEEE Transactions on Radiation and Plasma Medical Sciences. 2(5):388-403. https://doi.org/10.1109/TRPMS.2018.2846745S3884032
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