1,953 research outputs found

    Modelado y Simulaci贸n. Arquitectura de Computadores y Sistemas Ciberf铆sicos

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    Actualmente, una gran cantidad de procesos industriales complejos incluyen sistemas ciberf铆sicos, donde un sistema f铆sico (brazos rob贸ticos, dispositivos IoT, etc.) es controlado por algoritmos computacionales. Como ejemplo tenemos sistemas de red el茅ctrica inteligente, autom贸viles aut贸nomos, sistemas de control de procesos industriales, entre otros. La optimizaci贸n en el uso de recursos computacionales en estos sistemas ciberf铆sicos as铆 como la monitorizaci贸n online y actuaci贸n autom谩tica son desaf铆os que est谩n siendo abordados actualmente en un gran n煤mero de proyectos de investigaci贸n.CONACYT 鈥 Consejo Nacional de Ciencia y Tecnolog铆aPROCIENCI

    Fault tolerance at system level based on RADIC architecture

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    The increasing failure rate in High Performance Computing encourages the investigation of fault tolerance mechanisms to guarantee the execution of an application in spite of node faults. This paper presents an automatic and scalable fault tolerant model designed to be transparent for applications and for message passing libraries. The model consists of detecting failures in the communication socket caused by a faulty node. In those cases, the affected processes are recovered in a healthy node and the connections are reestablished without losing data. The Redundant Array of Distributed Independent Controllers architecture proposes a decentralized model for all the tasks required in a fault tolerance system: protection, detection, recovery and masking. Decentralized algorithms allow the application to scale, which is a key property for current HPC system. Three different rollback recovery protocols are defined and discussed with the aim of offering alternatives to reduce overhead when multicore systems are used. A prototype has been implemented to carry out an exhaustive experimental evaluation through Master/Worker and Single Program Multiple Data execution models. Multiple workloads and an increasing number of processes have been taken into account to compare the above mentioned protocols. The executions take place in two multicore Linux clusters with different socket communications libraries

    An approach for an efficient execution of SPMD applications on Multi-core environments

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    Executing traditional Message Passing Interface (MPI) applications on multi-core cluster balancing speed and computational efficiency is a difficult task that parallel programmers have to deal with. For this reason, communications on multi-core clusters ought to be handled carefully in order to improve performance metrics such as efficiency, speedup, execution time and scalability. In this paper we focus our attention on SPMD (Single Program Multiple Data) applications with high communication volume and synchronicity and also following characteristics such as: static, local and regular. This work proposes a method for SPMD applications, which is focused on managing the communication heterogeneity (different cache level, RAM memory, network, etc.) on homogenous multi-core computing platform in order to improve the application efficiency. In this sense, the main objective of this work is to find analytically the ideal number of cores necessary that allows us to obtain the maximum speedup, while the computational efficiency is maintained over a defined threshold (strong scalability). This method also allows us to determine how the problem size must be increased in order to maintain an execution time constant while the number of cores are expanded (weak scalability) considering the tradeoff between speed and efficiency. This methodology has been tested with different benchmarks and applications and we achieved an average improvement around 30.35% of efficiency in applications tested using different problems sizes and multi-core clusters. In addition, results show that maximum speedup with a defined efficiency is located close to the values calculated with our analytical model with an error rate lower than 5% for the applications tested

    RADIC : un middleware de tolerancia a fallos que preserva el rendimiento

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    La tolerancia a fallos es una l铆nea de investigaci贸n que ha adquirido una importancia relevante con el aumento de la capacidad de c贸mputo de los s煤per-computadores actuales. Esto es debido a que con el aumento del poder de procesamiento viene un aumento en la cantidad de componentes que trae consigo una mayor cantidad de fallos. Las estrategias de tolerancia a fallos actuales en su mayor铆a son centralizadas y estas no escalan cuando se utiliza una gran cantidad de procesos, dado que se requiere sincronizaci贸n entre todos ellos para realizar las tareas de tolerancia a fallos. Adem谩s la necesidad de mantener las prestaciones en programas paralelos es crucial, tanto en presencia como en ausencia de fallos. Teniendo en cuenta lo citado, este trabajo se ha centrado en una arquitectura tolerante a fallos descentralizada (RADIC - Redundant Array of Distributed and Independant Controllers) que busca mantener las prestaciones iniciales y garantizar la menor sobrecarga posible para reconfigurar el sistema en caso de fallos. La implementaci贸n de esta arquitectura se ha llevado a cabo en la librer铆a de paso de mensajes denominada Open MPI, la misma es actualmente una de las m谩s utilizadas en el mundo cient铆fico para la ejecuci贸n de programas paralelos que utilizan una plataforma de paso de mensajes. Las pruebas iniciales demuestran que el sistema introduce m铆nima sobrecarga para llevar a cabo las tareas correspondientes a la tolerancia a fallos. MPI es un est谩ndar por defecto fail-stop, y en determinadas implementaciones que a帽aden cierto nivel de tolerancia, las estrategias m谩s utilizadas son coordinadas. En RADIC cuando ocurre un fallo el proceso se recupera en otro nodo volviendo a un estado anterior que ha sido almacenado previamente mediante la utilizaci贸n de checkpoints no coordinados y la relectura de mensajes desde el log de eventos. Durante la recuperaci贸n, las comunicaciones con el proceso en cuesti贸n deben ser retrasadas y redirigidas hacia la nueva ubicaci贸n del proceso. Restaurar procesos en un lugar donde ya existen procesos sobrecarga la ejecuci贸n disminuyendo las prestaciones, por lo cual en este trabajo se propone la utilizaci贸n de nodos spare para la recuperar en ellos a los procesos que fallan, evitando de esta forma la sobrecarga en nodos que ya tienen trabajo. En este trabajo se muestra un dise帽o propuesto para gestionar de un modo autom谩tico y descentralizado la recuperaci贸n en nodos spare en un entorno Open MPI y se presenta un an谩lisis del impacto en las prestaciones que tiene este dise帽o. Resultados iniciales muestran una degradaci贸n significativa cuando a lo largo de la ejecuci贸n ocurren varios fallos y no se utilizan spares y sin embargo utiliz谩ndolos se restablece la configuraci贸n inicial y se mantienen las prestaciones.Fault tolerance is a research line that has gained significant importance with the increasing of the computing power of today's super-computers. The increasing of processing power comes with an increase in the number of components that brings also an increase in the number of failures. Today's fault tolerance strategies are mostly centralized and these do not scale when using a large number of processes, since synchronization is required between them to perform the fault tolerance tasks. Maintain performance in parallel applications is crucial, in the presence or absence of fault. According to the above, this work has focused on a decentralized fault-tolerant architecture (RADIC - Redundant Array of Distributed and Independant Controllers) that seeks to maintain the initial performance and ensure the lowest possible overhead to reconfigure the system in case of failure. The implementation of this architecture has been made in the message passing library called Open MPI. This is one of the most used message passing library in the scientific world to execute parallel programs. Initial tests show that the system introduces minimal overhead to perform fault tolerances tasks, and also show that performance is restored as it was before failure. MPI is a fail-stop standard and some implementations that add fault tolerances use a coordinated strategy. In RADIC when a failure occur the failed process recovers in another node rolling back to a previous saved state made by using an uncoordinated strategy of checkpoint and by reprocessing the saved log. During restart, the communications with the failed process should be delayed and redirected to the new process location. Restoring processes in a place where processes already exists overload the application and the performance decrease. In this work is proposed the inclusion of spare nodes to restore failed processes in them, avoiding performance degradation. In this work we propose an automatic and decentralized method to manage the recovery of failed processes in spare nodes in an Open MPI environment and is also presented an analysis of the failure impact in the performance. Experimental evaluation shows a significant degradation when failures occur along a parallel execution and there is no spare nodes, nevertheless by using spares, the initial configuration and the initial performance may be restored

    Hybrid Message Pessimistic Logging : improving current pessimistic message logging protocols

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    With the growing scale of HPC applications, there has been an increase in the number of interruptions as a consequence of hardware failures. The remarkable decrease of Mean Time Between Failures (MTBF) in current systems encourages the research of suitable fault tolerance solutions. Message logging combined with uncoordinated checkpoint compose a scalable rollback-recovery solution. However, message logging techniques are usually responsible for most of the overhead during failure-free executions. Taking this into consideration, this paper proposes the Hybrid Message Pessimistic Logging (HMPL) which focuses on combining the fast recovery feature of pessimistic receiver-based message logging with the low failure-free overhead introduced by pessimistic sender-based message logging. The HMPL manages messages using a distributed controller and storage to avoid harming system's scalability. Experiments show that the HMPL is able to reduce overhead by 34% during failure-free executions and 20% in faulty executions when compared with a pessimistic receiver-based message logging

    Dexamethasone sensitizes to ferroptosis by glucocorticoid receptor-induced dipeptidase-1 expression and glutathione depletion

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    Dexamethasone is widely used as an immunosuppressive therapy and recently as COVID-19 treatment. Here, we demonstrate that dexamethasone sensitizes to ferroptosis, a form of iron-catalyzed necrosis, previously suggested to contribute to diseases such as acute kidney injury, myocardial infarction, and stroke, all of which are triggered by glutathione (GSH) depletion. GSH levels were significantly decreased by dexamethasone. Mechanistically, we identified that dexamethasone up-regulated the GSH metabolism regulating protein dipeptidase-1 (DPEP1) in a glucocorticoid receptor (GR)-dependent manner. DPEP1 knockdown reversed the phenotype of dexamethasone-induced ferroptosis sensitization. Ferroptosis inhibitors, the DPEP1 inhibitor cilastatin, or genetic DPEP1 inactivation reversed the dexamethasone-induced increase in tubular necrosis in freshly isolated renal tubules. Our data indicate that dexamethasone sensitizes to ferroptosis by a GR-mediated increase in DPEP1 expression and GSH depletion. Together, we identified a previously unknown mechanism of glucocorticoid-mediated sensitization to ferroptosis bearing clinical and therapeutic implications

    Silencing the CSF-1 Axis Using Nanoparticle Encapsulated siRNA Mitigates Viral and Autoimmune Myocarditis

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    Myocarditis is an inflammatory disease of the heart muscle most commonly caused by viral infection and often maintained by autoimmunity. Virus-induced tissue damage triggers chemokine production and, subsequently, immune cell infiltration with pro-inflammatory and pro-fibrotic cytokine production follows. In patients, the overall inflammatory burden determines the disease outcome. Following the aim to define specific molecules that drive both immunopathology and/or autoimmunity in inflammatory heart disease, here we report on increased expression of colony stimulating factor 1 (CSF-1) in patients with myocarditis. CSF-1 controls monocytes originating from hematopoietic stem cells and subsequent progenitor stages. Both, monocytes and macrophages are centrally involved in mediating tissue damage and fibrotic scarring in the heart. CSF-1 influences monocytes via engagement of CSF-1 receptor, and it is also produced by cells of the mononuclear phagocyte system themselves. Based on this, we sought to modulate the virus-triggered inflammatory response in an experimental model of Coxsackievirus B3-induced myocarditis by silencing the CSF-1 axis in myeloid cells using nanoparticle-encapsulated siRNA. siCSF-1 inverted virus-mediated immunopathology as reflected by lower troponin T levels, a reduction of accumulating myeloid cells in heart tissue and improved cardiac function. Importantly, pathogen control was maintained and the virus was efficiently cleared from heart tissue. Since viral heart disease triggers heart-directed autoimmunity, in a second approach we investigated the influence of CSF-1 upon manifestation of heart tissue inflammation during experimental autoimmune myocarditis (EAM). EAM was induced in Balb/c mice by immunization with a myocarditogenic myosin-heavy chain-derived peptide dissolved in complete Freund's adjuvant. siCSF-1 treatment initiated upon established disease inhibited monocyte infiltration into heart tissue and this suppressed cardiac injury as reflected by diminished cardiac fibrosis and improved cardiac function at later states. Mechanistically, we found that suppression of CSF-1 production arrested both differentiation and maturation of monocytes and their precursors in the bone marrow. In conclusion, during viral and autoimmune myocarditis silencing of the myeloid CSF-1 axis by nanoparticle-encapsulated siRNA is beneficial for preventing inflammatory tissue damage in the heart and preserving cardiac function without compromising innate immunity's critical defense mechanisms

    Adaptation of HIV-1 Envelope Glycoprotein gp120 to Humoral Immunity over the Course of the Epidemic

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    Since 2009, a large panel of broad and potent monoclonal neutralizing antibodies (MoNAbs) against HIV-1 have been isolated. These MoNAbs can protect from lllV-1 infection and suppress established infection in animal models. Because their efficacy should be evaluated in human clinical trials, it is of importance to define the sensitivity of the most contemporary transmitted variants to these MoNAbs. We, and others previously, reported that HIV-1 has become more resistant to neutralization over the course of the epidemic (Bunnik et al., Nature Med 2010, Bouvin-Pley et al., PloS Pathog 2013). Methods: Here we extended the analyses to the most potent MoNAbs described since then, either more recently isolated or improved by structure-based gene modifications. Results: We fully confirmed the first observations showing an increasing resistance of HIV-1 clade B over time to MoNAbs targeting the major gp l20 epitopes but not to MoNAbs targeting the gp41 MPER. Despite this evolution, some MoNAbs still were able to neutralize efficiently the most recently transmitted HIV-1 variants (2006-2010). The most potent MoNAbs were the bi-specific PG9- and PG16-iMab that alone were able to neutralize an variants at less than 0.4 mg/mL. The sensitivity to iMAb remained similar over time, suggesting that the trend of increasing resistance to PG9-/PG16-iMAb may be attributed only to die antigen binding domain of PG9/PG16. NIH45-46m2 (and -m7), 10-1074 and 10E8 were also highly potent and, if combined, reached the potency of PG9-/PG16-iMAb. We also observed that 3BNC 117 was almost as potent as the modified NIH45-46 antibodies, and that the lama-derived JM4IgG2b was the most potent Ab among those that do not target the major gp 120 neutralizing epitopes. Conclusions: These data clearly suggest a continuous drift of the env gene of HIV-1 elude B over the epidemic, and that not a single epitope is concerned but the entire gp120 as a whole. The consequences of this adaptation on the envelope functionality are being explored

    Early twentieth-century Vogue, George Wolfe Plank and the "Freaks of Mayfair"

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    Vogue was one of the most influential fashion magazines of the twentieth century. In the 1920s its British edition, launched in 1916, became a focus for various forms of queer visual and cultural expression. The origins of the related 鈥榓musing style鈥, which delighted in camp display, can be traced to the romantic and artistic collaboration between the American artist George Wolfe Plank and the British writer E. F. Benson during World War One. The illustrations that Plank produced for Benson鈥檚 book of satirical sketches of life in London鈥檚 high society, The Freaks of Mayfair (1916), shed light on the camp images that Plank designed for the covers of both the American and British editions of the magazine. Therefore, Plank can be understood to have played a key role in the development of queer visual culture during the early twentieth century

    In situ observations of the Swiss periglacial environment using GNSS instruments

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    Monitoring of the periglacial environment is relevant for many disciplines including glaciology, natural hazard management, geomorphology, and geodesy. Since October 2022, Rock Glacier Velocity (RGV) is a new Essential Climate Variable (ECV) product within the Global Climate Observing System (GCOS). However, geodetic surveys at high elevation remain very challenging due to environmental and logistical reasons. During the past decades, the introduction of low-cost global navigation satellite system (GNSS) technologies has allowed us to increase the accuracy and frequency of the observations. Today, permanent GNSS instruments enable continuous surface displacement observations at millimetre accuracy with a sub-daily resolution. In this paper, we describe decennial time series of GNSS observables as well as accompanying meteorological data. The observations comprise 54 positions located on different periglacial landforms (rock glaciers, landslides, and steep rock walls) at altitudes ranging from 2304 to 4003鈥塵a.s.l. and spread across the Swiss Alps. The primary data products consist of raw GNSS observables in RINEX format, inclinometers, and weather station data. Additionally, cleaned and aggregated time series of the primary data products are provided, including daily GNSS positions derived through two independent processing tool chains. The observations documented here extend beyond the dataset presented in the paper and are currently continued with the intention of long-term monitoring. An annual update of the dataset, available at https://doi.org/10.1594/PANGAEA.948334 (Beutel et聽al.,聽2022),鈥嬧嬧嬧嬧嬧嬧 is planned. With its future continuation, the dataset holds potential for advancing fundamental process understanding and for the development of applied methods in support of e.g. natural hazard management
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