Virtualización del sistema operativo FreeBSD sobre Xen

El sistema operativo FreeBSD soporta distintos modos de virtualización sobre la plataforma Xen. Cada uno usa una técnicas de virtualización distinta, logrando mayor o menor integración con el hipervisor. Actualmente, están soportados en FreeBSD el modo paravirtualizado, virtualizado asistido por hardware y modos híbridos. Este trabajo consiste fundamentalmente en un estudio práctico de los distintos modos de virtualización Xen soportados en FreeBSD, basándose en pruebas de sintéticas de rendimiento. Se incluye una comparativa con gráficas de los resultados obtenidos mediante un sistema de pruebas automáticas desarrollado en shell script y R. ABSTRACT. The FreeBSD operative system supports several virtualization modes when used over the Xen platform. Each mode uses a different virtualization technique, achieving different level of integration with the hypervisor. Current supported modes on FreeBSD are paravirtualized mode, hardware virtualization assisted and hybrid modes. This work is a survey on FreeBSD virtualization over Xen, focused on performance by benchmark testing all supported virtual machine implementations. The study includes a comparative of the measured test results performed by an automatic testing tool developed on shell and R script.

Size, blood organochlorine pesticide concentrations and biochemical indicators measured in hawksbill sea turtles (Eretmochelys imbricata) nesting at Punta Xen (Campeche, Mexico) in August 2010

The impact of environmental pollution on the homeostasis of sea turtles remains scarce, particularly in the southern Gulf of Mexico. As many municipalities do not rely on a waste treatment plant along the coastline of the Yucatan Peninsula, the vulnerability of these specimens could results enhanced. We searched for relationships between presence of organochlorine pesticides (OCP) and the level of several oxidative and pollutant stress indicators of the hawksbill sea turtle (Eretmochelys imbricata) during the egg-laying period 2010 at Punta Xen (Campeche, Mexico). Endosulfans, aldrin related (aldrin, endrin, dieldrin, endrin ketone, endrin aldehyde) and dichlorodiphenyldichloroethylene (DDT) families were detected in 17, 21 and 26 of the 30 sampled sea turtles, respectively. Significant correlation existed between the size of sea turtles with the concentration of methoxychlor, cholinesterase activity in plasma and heptachlors family, and catalase activity and hexachlorohexane family. Cholinesterase activity in washed erythrocytes and lipid peroxidation were positively correlated with glutathione reductase activity. Antioxidant enzyme actions seem adequate as no lipids damages were correlated with any OCPs. Future studies are necessary to evaluate the effect of OCPs on males of the area because of the significant detection of methoxychlor that target endocrine functioning and increase its concentration with size of the sea turtles.

Private cloud computing platforms. Analysis and implementation in a Higher Education Institution

The constant evolution of the Internet and its increasing use and subsequent entailing to private and public activities, resulting in a strong impact on their survival, originates an emerging technology. Through cloud computing, it is possible to abstract users from the lower layers to the business, focusing only on what is most important to manage and with the advantage of being able to grow (or degrades) resources as needed. The paradigm of cloud arises from the necessity of optimization of IT resources evolving in an emergent and rapidly expanding and technology. In this regard, after a study of the most common cloud platforms and the tactic of the current implementation of the technologies applied at the Institute of Biomedical Sciences of Abel Salazar and Faculty of Pharmacy of Oporto University a proposed evolution is suggested in order adorn certain requirements in the context of cloud computing.

Avaluació d'aplicacions HPC sobre Clouds públics / privats

Treball final de carrera (TFC) de l'Enginyeria Tècnica d'Informàtica de Gestió: avaluació d'aplicacions HPC sobre Clouds públics / privats.

Infraestructuras com servicio en arquitecturas de nubes privadas

El objetivo de este trabajo es proporcionar una arquitectura de nube privada basada en sistemas virtualizados, desarrollando el concepto de IaaS, donde la arquitectura propuesta ofrece un nuevo modelo de servicio orientado especialmente a unainfraestructura que a su vez permita ofrecer el servicio de escritorios y servidores virtualizados al personal de la Fundación i2CAT.

Les percepcions sensorials, un mitjà per conèixer el món

Vivim en un món desbordat de sons, olors, imatges,.. que sovint adquirei-xen transparència en els ulls dels adults, no obstant durant la infància es posseeix una mirada molt oberta del món, però el dia a dia, les rutines i convencionalismes redueixen les percepcions que es reben de l’entorn. Tre-ballar i fer ús dels sentits desperta i situa a l’infant en posició de ser partícip del món que l’envolta i ajuda a la comprensió i expressió de tot allò que sent i percep. Mitjançant la metodologia de l’experimentació i l’art és possi-ble el desenvolupament de les percepcions sensorials, a través de les quals la ment comença a construir les seves pròpies idees del món. La sensibilitat en la manera de percebre la realitat permet obtenir noves perspectives, així com maneres d’expressar i comunicar, de forma creativa, tot allò que es percep.

Materiales para una educaci??n antirracista

Los autores est??n integrados en el Seminario de educaci??n antirracista, dentro de la Plataforma Asturiana de Educaci??n Cr??tica

Formaci??n de actitudes interculturales en la Educaci??n Secundaria : un programa de educaci??n intercultural

Esta investigaci??n parte del an??lisis de los distintos modelos de educaci??n intercultural y la necesidad de dise??ar programas educativos estructurados para desarrollar actitudes interculturales en la escuela. Estos programas est??n centrados en estrategias educativas de participaci??n activa, aprendizaje cooperativo y comunicaci??n persuasiva. Han basado el dise??o cuasi-experimental en la Teor??a de la Acci??n Razonada de Fishebein y Ajzen. El an??lisis estad??stico de los resultados confirma que las actitudes hacia la diversidad cultural mostradas por los alumnos que participaron en el programa mejoraron significativamente. La principal conclusi??n que se extrae se??ala la necesidad de ense??ar actitudes interculturales en todas las escuelas para prevenir las actitudes racistas y xen??fobas que se desarrollan si no se interviene pedag??gicamente. Los efectos positivos de este programa pueden incrementarse si se desarrolla a lo largo de todo el curso escolar y se implica toda la comunidad educativa.

Ética : libro del alumno y del profesor.

Este libro recoge una antología de textos, ejercicios y otros recursos, que tienen como finalidad introducir al alumno en la problemática del racismo y la xenofobia (situaciones de marginalidad, discriminación e intolerancia). El trabajo se centra en la búsqueda y análisis de información sobre tales problemas, que permita a los alumnos identificar y valorar las acciones y medidas que adoptan tanto las instituciones como los grupos o individuos en torno a los problemas reseñados. Tres núcleos organizan los contenidos seleccionados: 1.Desarrollo de las ideas racistas y-o xenófobas. 2.Problemas actuales relacionados con el racismo y-o xenofobia. 3.Proyectos éticos relacionados con el principio de la tolerancia. Todo ello se concreta en 6 unidades didácticas.

Contando cuentos : una experiencia did??ctica en el aula

Se plantea, como objetivo primordial, trasmitir valores al alumnado mediante la lectura de un cuento creado por una profesora de Lengua y Literatura. Se trabaja el tema de la inmigraci??n en Canarias y sus v??ctimas, que se relacionan con el acontecer cotidiano del alumnado, con lo que oye en los medios de comunicaci??n y en la calle. Se describe la b??squeda de una vida digna, de valores humanos, que deben ser trabajados en el aula para el crecimiento personal que se enriquece con la pluralidad. Tras la lectura, el alumnado reflexiona y debate sobre el tema de la inmigraci??n, afrontando posturas xen??fobas.

A recensi??n como plataforma nodal na formaci??n dun alumno de Historia

Resumen tomado de la publicaci??n

The assessment of benchmarks executed on bare-metal and using para-virtualization

A full assessment of para-­virtualization is important, because without knowledge about the various overheads, users can not understand whether using virtualization is a good idea or not. In this paper we are very interested in assessing the overheads of running various benchmarks on bare-­‐metal, as well as on para-­‐virtualization. The idea is to see what the overheads of para-­‐ virtualization are, as well as looking at the overheads of turning on monitoring and logging. The knowledge from assessing various benchmarks on these different systems will help a range of users understand the use of virtualization systems. In this paper we assess the overheads of using Xen, VMware, KVM and Citrix, see Table 1. These different virtualization systems are used extensively by cloud-­‐users. We are using various Netlib1 benchmarks, which have been developed by the University of Tennessee at Knoxville (UTK), and Oak Ridge National Laboratory (ORNL). In order to assess these virtualization systems, we run the benchmarks on bare-­‐metal, then on the para-­‐virtualization, and finally we turn on monitoring and logging. The later is important as users are interested in Service Level Agreements (SLAs) used by the Cloud providers, and the use of logging is a means of assessing the services bought and used from commercial providers. In this paper we assess the virtualization systems on three different systems. We use the Thamesblue supercomputer, the Hactar cluster and IBM JS20 blade server (see Table 2), which are all servers available at the University of Reading. A functional virtualization system is multi-­‐layered and is driven by the privileged components. Virtualization systems can host multiple guest operating systems, which run on its own domain, and the system schedules virtual CPUs and memory within each Virtual Machines (VM) to make the best use of the available resources. The guest-­‐operating system schedules each application accordingly. You can deploy virtualization as full virtualization or para-­‐virtualization. Full virtualization provides a total abstraction of the underlying physical system and creates a new virtual system, where the guest operating systems can run. No modifications are needed in the guest OS or application, e.g. the guest OS or application is not aware of the virtualized environment and runs normally. Para-­‐virualization requires user modification of the guest operating systems, which runs on the virtual machines, e.g. these guest operating systems are aware that they are running on a virtual machine, and provide near-­‐native performance. You can deploy both para-­‐virtualization and full virtualization across various virtualized systems. Para-­‐virtualization is an OS-­‐assisted virtualization; where some modifications are made in the guest operating system to enable better performance. In this kind of virtualization, the guest operating system is aware of the fact that it is running on the virtualized hardware and not on the bare hardware. In para-­‐virtualization, the device drivers in the guest operating system coordinate the device drivers of host operating system and reduce the performance overheads. The use of para-­‐virtualization [0] is intended to avoid the bottleneck associated with slow hardware interrupts that exist when full virtualization is employed. It has revealed [0] that para-­‐ virtualization does not impose significant performance overhead in high performance computing, and this in turn this has implications for the use of cloud computing for hosting HPC applications. The “apparent” improvement in virtualization has led us to formulate the hypothesis that certain classes of HPC applications should be able to execute in a cloud environment, with minimal performance degradation. In order to support this hypothesis, first it is necessary to define exactly what is meant by a “class” of application, and secondly it will be necessary to observe application performance, both within a virtual machine and when executing on bare hardware. A further potential complication is associated with the need for Cloud service providers to support Service Level Agreements (SLA), so that system utilisation can be audited.

Immunoglobulin G profile in hyperacute rejection after multivisceral xenotransplantation

Galvao FHF, Soler W, Pompeu E, Waisberg DR, Mello ES, Costa ACL, Teodoro W, Velosa AP, Capelozzi VL, Antonangelo L, Catanozi S, Martins A, Malbouisson LMS, Cruz RJ, Figueira ER, Filho JAR, Chaib E, D'Albuquerque LAC. Immunoglobulin G profile in hyperacute rejection after multivisceral xenotransplantation. Xenotransplantation 2012; 19: 298304. (c) 2012 John Wiley & Sons A/S. Abstract: Introduction: Xenotransplantation is a potential solution for the high mortality of patients on the waiting list for multivisceral transplantation; nevertheless, hyperacute rejection (HAR) hampers this practice and motivates innovative research. In this report, we describe a model of multivisceral xenotransplantation in which we observed immunoglobulin G (IgG) involvement in HAR. Methods: We recovered en bloc multivisceral grafts (distal esophagus, stomach, small intestine, colon, liver, pancreas, and kidneys) from rabbits (n = 20) and implanted them in the swine (n = 15) or rabbits (n = 5, control). Three hours after graft reperfusion, we collected samples from all graft organs for histological study and to assess IgG fixation by immunofluorescence. Histopathologic findings were graded according to previously described methods. Results: No histopathological features of rejection were seen in the rabbit allografts. In the swine-to-rabbit grafts, features of HAR were moderate in the liver and severe in esophagus, stomach, intestines, spleen, pancreas, and kidney. Xenograft vessels were the central target of HAR. The main lesions included edema, hemorrhage, thrombosis, myosites, fibrinoid degeneration, and necrosis. IgG deposition was intense on cell membranes, mainly in the vascular endothelium. Conclusions: Rabbit-to-swine multivisceral xenotransplants undergo moderate HAR in the liver and severe HAR in the other organs. Moderate HAR in the liver suggests a degree of resistance to the humoral immune response in this organ. Strong IgG fixation in cell membranes, including vascular endothelium, confirms HAR characterized by a primary humoral immune response. This model allows appraisal of HAR in multiple organs and investigation of the livers relative resistance to this immune response.

Applying partial virtualization on ELF binaries through dynamic loaders

The technology of partial virtualization is a revolutionary approach to the world of virtualization. It lies directly in-between full system virtual machines (like QEMU or XEN) and application-related virtual machines (like the JVM or the CLR). The ViewOS project is the flagship of such technique, developed by the Virtual Square laboratory, created to provide an abstract view of the underlying system resources on a per-process basis and work against the principle of the Global View Assumption. Virtual Square provides several different methods to achieve partial virtualization within the ViewOS system, both at user and kernel levels. Each of these approaches have their own advantages and shortcomings. This paper provides an analysis of the different virtualization methods and problems related to both the generic and partial virtualization worlds. This paper is the result of an in-depth study and research for a new technology to be employed to provide partial virtualization based on ELF dynamic binaries. It starts with a mild analysis of currently available virtualization alternatives and then goes on describing the ViewOS system, highlighting its current shortcomings. The vloader project is then proposed as a possible solution to some of these inconveniences with a working proof of concept and examples to outline the potential of such new virtualization technique. By injecting specific code and libraries in the middle of the binary loading mechanism provided by the ELF standard, the vloader project can promote a streamlined and simplified approach to trace system calls. With the advantages outlined in the following paper, this method presents better performance and portability compared to the currently available ViewOS implementations. Furthermore, some of itsdisadvantages are also discussed, along with their possible solutions.

Functional evaluation of hTM, CD46 and HLA-E transgenes in vitro and in pig leg xenoperfusion experiments

Background Besides α1,3 galactosyltransferase (Gal) gene knockout several transgene combinations to prevent pig-to-human xenograft rejection are being investigated. hCD46/HLA-E double transgenic pigs were tested for prevention of xenograft rejection in an ex vivo pig-to-human xenoperfusion model. In addition, expression of human thrombomodulin (hTM-) on wild-type and/or multi-transgenic (GalTKO/hCD46) background was evaluated to overcome pig-to-human coagulation incompatibility. Methods hCD46/HLA-E double transgenic as well as wild-type pig forelimbs were ex vivo perfused with whole, heparinized human blood and autologous blood, respectively. Blood samples were analyzed for production of porcine and/or human inflammatory cytokines. Biopsy samples were examined for deposition of complement proteins as well as E-selectin and VCAM-1 expression. Serial blood cell counts were performed to analyze changes in human blood cell populations. In vitro, PAEC were analyzed for ASGR1 mediated human platelet phagocytosis. In addition, a biochemical assay was performed using hTM-only and multi-transgenic (GalTKO/hCD46/hTM) pig aortic endothelial cells (PAEC) to evaluate the ability of hTM to generate activated protein C (APC). Subsequently, the anti-coagulant properties of hTM were tested in a microcarrier based coagulation assay with PAEC and human whole blood. Results No hyperacute rejection was seen in the ex vivo perfusion model. Extremity perfusions lasted for up to 12 h without increase of vascular resistance and had to be terminated due to continuous small blood losses. Plasma levels of porcine IL1β (P < 0.0001), and IL-8 (P = 0.019) as well as human C3a, C5a and soluble C5b-9 were significantly (P < 0.05–<0.0001) lower in blood perfused through hCD46/HLA-E transgenic as compared to wild-type limbs. C3b/c, C4b/c, and C6 deposition as well as E-selectin and VCAM-1 expression were significantly (P < 0.0001) higher in tissue of wild-type as compared to transgenic limbs. Preliminary immunofluorescence staining results showed that the expression of hCD46/HLA-E is associated with a reduction of NK cell tissue infiltration (P < 0.05). A rapid decrease of platelets was observed in all xenoperfusions. In vitro findings showed that PAEC express ASGR1 and suggest that this molecule is involved in human platelet phagocytosis. In vitro, we found that the amount of APC in the supernatant of hTM transgenic cells increased significantly (P < 0.0001) with protein C concentration in a dose-dependent manner as compared to control PAEC lacking hTM, where the turnover of the protein C remained at the basal level for all of the examined concentration. In further experiments, hTM also showed the ability to prevent blood coagulation by three- to four-fold increased (P < 0.001) clotting time as compared to wild-type PAEC. The formation of TAT complexes was significantly lower when hTM-transgenic cells (P < 0.0001) were used as compared to wild-type cells. Conclusions Transgenic hCD46/HLA-E expression clearly reduced humoral xenoresponses since the terminal pathway of complement, endothelial cell activation, inflammatory cytokine production and NK-cell tissue infiltration were all down-regulated. We also found ASGR1 expression on the vascular endothelium of pigs, and this molecule may thus be involved in binding and phagocytosis of human platelets during pig-to-human xenotransplantation. In addition, use of the hTM transgene has the potential to overcome coagulation incompatibilities in pig-to-human xenotransplantation.