Towards Formal Interaction-Based Models of Grid Computing Infrastructures

Grid computing (GC) systems are large-scale virtual machines, built upon a massive pool of resources (processing time, storage, software) that often span multiple distributed domains. Concurrent users interact with the grid by adding new tasks; the grid is expected to assign resources to tasks in a fair, trustworthy way. These distinctive features of GC systems make their specification and verification a challenging issue. Although prior works have proposed formal approaches to the specification of GC systems, a precise account of the interaction model which underlies resource sharing has not been yet proposed. In this paper, we describe ongoing work aimed at filling in this gap. Our approach relies on (higher-order) process calculi: these core languages for concurrency offer a compositional framework in which GC systems can be precisely described and potentially reasoned about.Comment: In Proceedings DCM 2013, arXiv:1403.768

Session-based concurrency in Maude:Executable semantics and type checking

Session types are a well-established approach to communication correctness in message-passing processes. Widely studied from a process calculi perspective, here we pursue an unexplored strand and investigate the use of the Maude system for implementing session-typed process languages and reasoning about session-typed process specifications. We present four technical contributions. First, we develop and implement in Maude an executable specification of the operational semantics of a session-typed π-calculus by Vasconcelos. Second, we also develop an executable specification of its associated algorithmic type checking, and describe how both specifications can be integrated. Third, we show that our executable specification can be coupled with reachability and model checking tools in Maude to detect well-typed but deadlocked processes. Finally, we demonstrate the robustness of our approach by adapting it to a higher-order session π-calculus, in which exchanged values include names but also abstractions (functions from names to processes). All in all, our contributions define a promising new approach to the (semi)automated analysis of communication correctness in message-passing concurrency

Dynamics of animal performance, and estimation of carbon footprint of two breeding herds grazing native neotropical savannas in eastern Colombia

The savannas of eastern Colombia located in the Orinoco river basin represent 18% of the Latin American neotropical savannas, and those areas that are tillable and closer to markets are subject to considerable anthropic pressure in the quest for intensification. Historically, and even today, beef cattle production constitutes the main land use, and much of it is subjected to extensive management. This paper describes for the first time, the use of cattle grazing experiments to assess methane (CH4) emissions from neotropical savanna-based beef breeding systems, and with the support of published research conducted next to them, estimates of the carbon (C) footprint in carbon dioxide equivalents (CO2-eq) for the whole system. Over 5 years and covering complete reproductive cycles, a conventional weaning (CW) herd system was compared to an early weaning (EW) herd system, that represented a modest degree of more intensive savanna management. Differences were found between the two management practices in total CH4 emissions, emission intensities [kg CH4 kg –1 calf born and kg CH4 kg –1 liveweight gain (LWG)] and emission efficiencies (kg CO2-eq kg –1 calf born and kg CH4 kg –1 LWG), that mostly associated with the different lactation lengths. When both herd systems were carried over until calves, later yearlings, reached to 25 months of age, the differences in favor of EW breeding herd system were diminished. The calculated C footprint in (CO2-eq) of both management practices was near neutral subjected to a number of assumptions and the use of limited published information on savanna C stocks and CH4 and nitrous oxide (N2O) emissions from soil, and it is posited that both herd systems were nearly in equilibrium. The available data and results show the need for further information on the neotropical savanna C stocks and C sequestration potential of soils of the Orinoco river basin. More reliable datasets regarding below-ground C inputs and CH4 and N2O emissions from soil are needed to provide a useful basal benchmark for, and approach to, future analyses of environmental impact of more intensive beef herd systems in the region

The community structure and microbial linkage of rumen protozoa and methanogens in response to the addition of tea seed saponins in the diet of beef cattle

© 2020 The Author(s). Background: This study investigated changes in rumen protozoal and methanogenic communities, along with the correlations among microbial taxa and methane (CH4) production of six Belmont Red Composite beef steers fed tea seed saponins (TSS). Animals were fed in three consecutive feeding periods, a high-grain basal diet for 14 d (BD period) then a period of progressive addition of TSS to the basal diet up to 30 g/d for 20 d (TSS period), followed by the basal diet for 13 d without TSS (BDP post-control period). Results: The study found that TSS supplementation decreased the amount of the protozoal genus Entodinium and increased Polyplastron and Eudiplodinium genera. During BDP period, the protozoa community of steers did not return to the protozoal profiles observed in BD period, with higher proportions of Metadinium and Eudiplodinium and lower Isotricha. The addition of TSS was found to change the structure of methanogen community at the sub-genus level by decreasing the abundance of methanogens in the SGMT clade and increasing the abundance of methanogens in the RO clade. The correlation analysis indicated that the abundance of SGMT clade methanogens were positively correlated with Isotricha, and Isotricha genus and SGMT clade methanogens were positively correlated with CH4 production. While RO clade were positively correlated with the proportion of Metadinium genus, which was negatively correlated with CH4 emission. Conclusions: These results suggest that different genera of rumen protozoa ciliates appear to be selectively inhibited by TSS, and the change in methanogen community at the subgenus level may be due to the mutualistic relationships between methanogens and rumen ciliates

The carbon footprint of young-beef cattle finishing systems in the Eastern Plains of the Orinoco River Basin of Colombia

Introduction: Previous research has shown increased productivity amongst sown grass pastures compared to native savanna pastures by year-round grazing for fattening of adult and young Brahman (Bos indicus)-bred cattle in the well-drained native savanna ecosystem of the Colombian Orinoquía. But there is limited information on the carbon footprint (CF) of commercial young-Brahman heifers and steers reared throughout life on well-managed Brachiaria decumbens Stapf pastures. Methods: The present study characterized growth, lifetime enteric methane (CH4) emissions, carcass carbon dioxide equivalent (CO2-eq) CH4 efficiency intensities (i.e., emissions per kg of product), and estimated the overall CF of young cattle grazing B. decumbens pastures subject to a range of daily liveweight gains (DLWGs; 0.428 – 0.516 kg) and fattening framework (405 – 574 kg). Weaning data from seven consecutive calving seasons in a commercial Brahman breeding herd continuously grazed on B. decumbens were integrated with a Microsoft Excel® dynamic greenhouse gas emission (GHGE) simulation of stockers-yearlings, and seven fattening, and processing scenarios. Results: The model predicted that heifers subject to low and high DLWGs (0.428 vs 0.516 kg) and steers (0.516 kg) may be successfully fattened without supplementation assuming that animals had access to a well-managed grass pasture. Depending on the fattening strategy, kg CO2-eq CH4/kg edible protein values ranged from 66.843 to 87.488 ± 0.497 for heifers and from 69.689 to 91.291 ± 0.446 for steers. Discussion: Assuming that forage on offer is at least 1,500-2,000 kg of dry matter/ha during the rainy season, all the simulated systems showed potential for C neutrality and net-zero C emission when considering GHGEs from the soil, pasture, and animal components vs the estimated soil C capture over seven seasons. However, under a more optimistic scenario, these beef systems could accomplish substantial net gains of soil C, over the period for which field data are available. Overall, this study projects the positive impact of the design of plausible fattening strategies on grasslands for improving cattle productivity and reducing emission intensities with concomitant increases in technical efficiency

Caracterización mecánica y microestructural de acero naval sometido a cargas dinámicas por explosión

The work presents the mechanical and micro-structural characterization of the grade A ASTM A 131 steel laminate that form naval panels (reinforced laminate with defined ratios aspect l/b), attained by means of destructive testing, to establish the mechanical response of naval structures submitted to those types of charges. Measurements of micro-hardness, grain size and tension tests of specimens of the material were carried out before and after the impact. The material hit was selected from structural panels submitted to controlled explosions generated nearby with 25g charges of pentolite, placed at predetermined distances. For the characterization, panels with the presence of fissures were rejected. Important variations in micro-hardness and mechanical characteristics appeared; nevertheless, significant micro-structural changes were not observed in grain size.El trabajo presenta la caracterización mecánica y microestructural de láminas de acero ASTM A 131 grado A que conforman paneles navales (láminas reforzadas con relaciones de aspecto l/b definidas), realizada mediante ensayos destructivos, para establecer la respuesta mecánica de estructuras navales sometidas a ese tipo de cargas. Se hicieron mediciones de microdureza, tamaño de grano y ensayos de tensión a especímenes del material antes y después del impacto. El material impactado fue seleccionado de paneles estructurales sometidos a explosiones controladas cercanas generadas con cargas de 250 g de pentolita, dispuestas a distancias predeterminadas. Para la caracterización se rechazaron paneles con la presencia de fisuras. Se presentaron variaciones importantes en microdureza y características mecánicas, sin embargo, no se observaron cambios microestructurales en tamaño de grano que fueran significativos

Charophyta, Chlorophyta y Cryptophyta del embalse Riogrande II (Antioquia), Colombia

In monthly samples collected from August 2011 to August 2012 in the Riogrande II reservoir (Grande River drainage, Antioquia, Colombia). 29 genera, 48 species and one taxonomic variety belonging to Charophyta, Chlorophyta and Cryptophyta were identified. 18 species and one variety are new reports to the algal flora of Colombia. Chlorophyta was the Division with the largest number of genera and Staurastrum (Charophyta) the most diverse genus and also the largest contributer to biomass. Differences from the characteristics described in the literature and those observed in the specimens studied, made some taxonomic identification rather difficult, pointing out the need for careful and meticulous morphological studies before reaching taxonomical identifications.En muestras recolectadas mensualmente, entre agosto de 2011 y agosto de 2012, en el embalse Riogrande II(cuenca del río Grande, Antioquia, Colombia), se identificaron en total 29 géneros, 48 especies y una variedadtaxonómica, pertenecientes a Charophyta, Chlorophyta y Cryptophyta. De las 48 especies, 18 especies y unavariedad, son nuevos reportes para la ficoflórula colombiana. La división con mayor número de géneros fueChlorophyta, sin embargo, Staurastrum (Charophyta) fue el género más diverso y de mayor contribución a labiomasa. Las diferencias entre las características descritas en la literatura y las observadas en los ejemplares,dificultaron la determinación taxonómica, lo cual plantea la necesidad de realizar estudios morfológicosdetallados

Charophyta, Chlorophyta y Cryptophyta del embalse Riogrande II (Antioquia), Colombia

En muestras recolectadas mensualmente, entre agosto de 2011 y agosto de 2012, en el embalse Riogrande II (cuenca del río Grande, Antioquia, Colombia), se identificaron en total 29 géneros, 48 especies y una variedad taxonómica, pertenecientes a Charophyta, Chlorophyta y Cryptophyta. De las 48 especies, 18 especies y una variedad, son nuevos reportes para la ficoflórula colombiana. La división con mayor número de géneros fue Chlorophyta, sin embargo, Staurastrum (Charophyta) fue el género más diverso y de mayor contribución a la biomasa. Las diferencias entre las características descritas en la literatura y las observadas en los ejemplares, dificultaron la determinación taxonómica, lo cual plantea la necesidad de realizar estudios morfológicos detallados