Teaching “Embedded Operating Systems” using Raspberry Pi and Virtual Machines

Embedded systems design, implementation and programming is an important topic in many curricula of Computer Science and Computer Engineering. This paper describes the estructure of a course on Embedded Operating Systems included in the Degree in Computer Science at the University of Valladolid. The course core elements are the use of virtual machines and Raspberry Pi kits. Our experience shows that the topics covered and the project-based methodology lead to excellent results in terms of student progression.Universidad de Granada: Departamento de Arquitectura y Tecnología de Computadores; Vicerrectorado para la Garantía de la Calida

Modeling dust emission in PN IC 418

We investigated the infrared (IR) dust emission from PN IC 418, using a detailed model controlled by a previous determination of the stellar properties and the characteristics of the photoionized nebula, keeping as free parameters the dust types, amounts and distributions relative to the distance of the central star. The model includes the ionized region and the neutral region beyond the recombination front (Photodissociation region, or PDR), where the [OI] and [CII] IR lines are formed. We succeeded in reproducing the observed infrared emission from 2 to 200~\mm. The global energy budget is fitted by summing up contributions from big grains of amorphous carbon located in the neutral region and small graphite grains located in the ionized region (closer to the central star). Two emission features seen at 11.5 and 30~\mm are also reproduced by assuming them to be due to silicon carbide (SiC) and magnesium and iron sulfides (Mg$_x$Fe$_{1-x}$S), respectively. For this, we needed to consider ellipsoidal shapes for the grains to reproduce the wavelength distribution of the features. Some elements are depleted in the gaseous phase: Mg, Si, and S have sub-solar abundances (-0.5 dex below solar by mass), while the abundance of C+N+O+Ne by mass is close to solar. Adding the abundances of the elements present in the dusty and gaseous forms leads to values closer to but not higher than solar, confirming that the identification of the feature carriers is plausible. Iron is strongly depleted (3 dex below solar) and the small amount present in dust in our model is far from being enough to recover the solar value. A remaining feature is found as a residue of the fitting process, between 12 and 25~\mm, for which we do not have identification.Comment: Accepted for publication in Astronomy & Astrophysics. V2: adding reference

Latitudinal and seasonal egg-size variation of the anchoveta (Engraulis ringens) off the Chilean coast

The anchoveta Engraulis ringens is widely distributed along the eastern South Pacific (from 4° to 42°S; Serra et al., 1979) and it has also supported one of the largest fisheries of the world over the last four decades. However, there are few interpopulation comparisons for either the adult or the younger stages. Reproductive traits, such as fecundity or spawning season length, are known to vary with latitude for some fish species (Blaxter and Hunter, 1982; Conover, 1990; Fleming and Gross, 1990; Castro and Cowen, 1991), and latitudinal trends for some early life history traits, such as egg size and larval growth rates, have been reported for others clupeiforms and other fishes (Blaxter and Hempel, 1963; Ciechomski, 1973; Imai and Tanaka, 1987, Conover 1990, Houde 1989). However, there is no published information on potential latitudinal trends during the adult or the early life history of the anchoveta, even though this type of information may help in understanding recruitment variability, especially during recurring large scale events (such as El Niño or La Niña) that affect the entire species range

High‐level parallel programming in a heterogeneous world

Producción CientíficaDuring the last decade, parallel programming has evolved in an unprecedent way. Fifteen years ago, the future of parallel computing seemed to consist on the advent of multicore processors composed by an ever-increasing number in the core count per CPU, and their interconnection to form larger clusters

Parallelization alternatives and their performance for the convex hull problem

Producción CientíficaHigh performance machines have become available nowadays to an increasing number of researchers. Most of us might have both an access to a supercomputing center and an algorithm that could benefit from these high performance machines. The aim of the present work is to revisit all existing parallelization alternatives, including emerging technologies like software-only speculative parallelization, to solve on different architectures the same representative problem: The computation of the convex hull of a point set.Part of this work was carried out while David Orden visited the Departamento de Informática, Universidad de Valladolid, with support of the Universidad de Alcalá

Review and Support of the Relationship between Alliance Competence and Alliance Orientation

This paper seeks to contribute to the understanding of the formation of strategic alliances among companies. Specifically, it seeks to understand the relationship between alliance competence (Lambe, Speakman & Hunt, 2002) and alliance orientation (Kandemir, Yaprak & Cavusgil, 2006), following some of the most important guidelines of the leading exponents of theories based on resources and dynamic capabilities.Once the concepts were developed we proceeded to establish a hypothesis that seeks to better understand the relationships between the constructs and how they interact to achieve alliances that are beneficial for the parties involved.In particular, the findings corroborate the proposed relationships, supporting a direct link between market orientation constructs and senior management commitment to the alliances, as well as the commitment of senior management and competencies for alliances. As a fundamental contribution to this work, a mediating role of the alliance orientation construct was also detected between the relationship of senior management commitment and alliance competence.Future research is proposed into the elements of the practical guidelines for alliances and the relationship of this construct with the others related to alliances and particularly to their performance

On the choice of the best chunk size for the speculative execution of loops

Producción CientíficaLoops are a rich source of parallelism. Unfortunately, many loops cannot be safely parallelized at compile time because the compiler is not able to guarantee that there will be no dependence violations. Thread-Level Speculation (TLS) techniques, either hardware or software-based, allow the parallel execution of non-analyzable loops, issuing the execution of blocks of consecutive iterations (called chunks) while a hardware or software monitor ensures that no dependence violations arise. If such a dependence violation occurs, the chunk that was fed with incorrect values is discarded and re-started, in order to consume the correct information. In the speculative execution of non-analyzable loops, it is very important to correctly choose the chunk size, because this choice dramatically affects the performance of the parallel execution. Bigger chunks imply less scheduling overheads, but smaller chunks allow fewer calculations to be discarded in the event of a dependence violation. To find a good chunk size is not a simple task, because loops may present dependencies that cannot be detected at compile time. In this paper, we present a comprehensive evaluation of different scheduling methods to estimate the optimal chunk size in the speculative execution of non-analyzable loops. This evaluation ranges from the simple, classical methods originally devised to achieve load balancing in loops with no dependencies, to methods that make some assumptions on the distribution pattern of dependencies, such as Meseta and Just-in-Time scheduling. We also propose and evaluate a general, more complex method called Moody Scheduling, that does not require a-priori assumptions to achieve the highest performance

Distributed programming of a hyperspectral image registration algorithm for heterogeneous GPU clusters

Producción CientíficaHyperspectral image registration is a relevant task for real-time applications such as environmental disaster management or search and rescue scenarios. The HYFMGPU algorithm was proposed as a single-GPU high-performance solution, but the need for a distributed version has arisen due to the continuous evolution of sensors that generate images with finer spatial and spectral resolutions. In a previous work, we simplified the programming of the multi-device parts of an initial MPI+CUDA multi-GPU implementation of HYFMGPU by means of Hitmap, a library to ease the programming of parallel applications based on distributed arrays. The performance of that Hitmap version was assessed in a homogeneous GPU cluster. In this paper, we extend this implementation by means of new functionalities added to the latest version of Hitmap in order to support arbitrary load distributions for multi-node heterogeneous GPU clusters. Three different load balancing layouts are tested, which prove that selecting a proper layout affects the performance of the code and how this performance is correlated with the use of the GPUs available in the cluster.This work has been funded by the Consejería de Educación of Junta de Castilla y León and the European Regional Development Fund (ERDF) program (projects PROPHET, VA082P17, and PROPHET-2, VA226P20); by the Ministerio de Economía, Industria y Competitividad of Spain (project PCAS, TIN2017-88614-R); and by the Fulbright Commission, (grant Salvador de Madariaga/Fulbright Scholar PRX17/00674)

Ultrastructure of STH cells in the pars distalis of the hypophysis of mice bearing transplanted hepatomas

An electron microscopic analysis was performed on the pars distalis of the hypophysis of mice bearing transplanted hepatomas. Normal mice served as controls. In animals bearing a fast growing as well as in those bearing a slow growing hepatoma, the STH cells presented changes indicating increased release and synthesis of its secretory product. These changes can be summarized as follows: 1) Increased number of granuledepleted STH cells which were very irregular in size and shape. 2) Very irregular and sometimes bizarre nuclei. 3) Plasma membranes irregular and convoluted. 4) Increased quantity of endoplasmic reticulum which appeared sometimes dilated and contained material of varying electron density. 5) Abundant, irregular and frequently ramified mitochondria. 6) Hypertrophic Golgi system with increased number of microvesicles. 7) Increased number of large lysosomes of different type. 8) Increased number of fat droplets.Facultad de Ciencias Médica