221 research outputs found
D,L-CARNITINE RESOLUTION BY FUSARIUM-OXYSPORUM
No full textL-Carnitine was obtained in 40% yield from D,L-octanoyl carnitine by enantioselective hydrolysis with a strain of Fusarium oxysporum
AMMONIUM LACTATE FROM DEPROTEINIZED ALFALFA JUICE BY STREPTOCOCCUS-FAECIUM
No full textDeproteinized alfalfa juice is a by-product of the mechanical fractionation of alfalfa to obtain protein. In this work the juice was used as the substrate for the production of ammonium lactate (l-lactic acid) by a strain of Streptococcus faecium. Batch fermentation with a constant pH of 5.8 gave 27.2 g/l of lactic acid (90% conversion and 1.1 g/l/h productivity) and 6×1012 cells/l after 24 h. Semicontinuous fermentation allowed the conversion of 3-times the volume of deproteinized juice after 44 h, finally giving 29.7 g/l of ammonium lactate (99% conversion and 2.5 g/l/h productivity) and 4-6×1012 cells/l
Fattori influenti sul ricorso al credito al consumo
No full textAtti della Giornata di studio su "Il credito al consumo", Terni, 29 aprile 200
COUNTDOWN: A Run-Time Library for Performance-Neutral Energy Saving in MPI Applications
No full textPower and energy consumption are becoming key challenges for the supercomputers' exascale race. HPC systems' processors waist active power during communication and synchronization among the MPI processes in large-scale HPC applications. However, due to the time scale at which communication happens, transitioning into low-power states while waiting for the completion of each communication may introduce unacceptable overhead. In this article, we present COUNTDOWN, a run-time library for identifying and automatically reducing the power consumption of the CPUs during communication and synchronization. COUNTDOWN saves energy without penalizing the time-to-completion by lowering CPUs power consumption only during idle times for which power state transition overhead is negligible. This is done transparently to the user, without requiring labor-intensive and error-prone application code modifications, nor requiring recompilation of the application. We test our methodology on a production Tier-1 system. For the NAS benchmarks, COUNTDOWN saves between 6 and 50 percent energy, with a time-to-solution penalty lower than 5 percent. In a complete production - Quantum ESPRESSO - for a 3.5K cores run, COUNTDOWN saves 22.36 percent energy, with a performance penalty below 3 percent. Energy saving increases to 37 percent with a performance penalty of 6.38 percent, if the application is executed without communication tuning
Roman bricks from the lagoon of Venice : a chemical characterization with multivariate analysis
No full textFrom 18 archaeological sites of the Lagoon of Venice 75 bricks belonging to Roman and medieval building levels have been analysed. Chemical composition and geometric measures allow the characterization of a group of 24 Roman bricks of Imperial age. The group formed by means of fuzzy c-means cluster analysis applied on chemical data have been tested by principal component analysis and finally subjected to discriminant analysis to estimate the relative weights of original variables and classify new elements. Correlations among the data of the major chemical elements confirm the reliability of the complex of chemical data. The aim of this research was to obtain a chemical characterization of Roman bricks (and later, of the medieval ones) coming from the lagoon of Venice thus making it possible: 1) to recognize the age of a brick by means of its chemical analysis; 2) to date the layers of archaeological excavations or the ground where there are medieval building foundations by means of membership bricks; 3) to calculate the rate of local ground lowering in the elapsed years by the difference in level from one layer to another; 4) to estimate local rates of land subsidence by comparison with mean values already know
Thermal Characterization of a Tier0 Datacenter Room in Normal and Thermal Emergency Conditions
No full textDatacenters are at the heart of the AI, Industry 4.0 and cloud revolution. A datacenter contains a large number of computing nodes hosted in a large temperature-controlled room. Due to the increasing total power and power density of computing nodes, the overall datacenter compute capacity is often capped by peak power consumption and temperature bottlenecks. To preserve the homogeneous performance assumption between all the nodes, complex cooling solution are required, but they might not be sufficient. In this work, we analysed and characterised the thermal properties of a Tier0 datacenter deploying advanced hybrid cooling technologies: specifically, we studied the spatial and temporal heterogeneity during production and cooling emergency hazards. This paper gives first quantitative evidence of thermal bottlenecks in real-life production workload, showing the presence of significant spatial thermal heterogeneity which could be exploited by thermal-aware job scheduling and datacenter-room run-time workload adaptation and distribution
COUNTDOWN - A run-time library for application-agnostic energy saving in MPI communication primitives
No full textEnergy and power consumption are prominent issues in today’s supercomputers and are foreseen as a limiting factor of future installations. In scientific computing, a significant amount of power is spent in the communication and synchronization-related idle times among distributed processes participating to the same application. However, due to the time scale at which communication happens, taking advantage of low-power states to reduce power in idle times in the computing resources, may introduce significant overheads. In this paper we present COUNTDOWN, a methodology and a tool for identifying and automatically reducing the frequency of the computing elements in order to save energy during communication and synchronization primitives. COUNTDOWN is able to filter out phases which would detriment the time to solution of the application transparently to the user, without touching the application code nor requiring recompilation of the application. We tested our methodology in a production Tier-0 system, a production application - Quantum ESPRESSO (QE) - with production datasets which can scale up to 3.5K cores. Experimental results show that our methodology saves 22.36% of energy consumption with a performance penalty of 2.88% in real production MPI-based application
Perturbed graphs achieve unit transport efficiency without environmental noise
No full textCoherent transport of an excitation through a network corresponds to continuous-time quantum walk on a graph, and the transport properties of the system may be radically different depending on the graph and on the initial state. The transport efficiency, i.e., the integrated probability of trapping at a certain vertex, is a measure of the success rate of the transfer process. Purely coherent quantum transport is known to be less efficient than the observed excitation transport, e.g., in biological systems, and there is evidence that environmental noise is indeed crucial for excitation transport. At variance with this picture, we here address purely coherent transport on highly symmetric graphs, and show analytically that it is possible to enhance the transport efficiency without environmental noise, i.e., using only a minimal perturbation of the graph. In particular, we show that adding an extra weight to one or two edges, depending on whether the initial state is localized or in a superposition of two vertex states, breaks the inherent symmetries of the graph and may be sufficient to achieve unit transport efficiency. We also briefly discuss the conditions to obtain a null transport efficiency, i.e., to avoid trapping
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