57 research outputs found
The ALICE Data Challenges
Since 1998, the ALICE experiment and the CERN/IT division have jointly executed several large-scale high throughput distributed computing exercises: the ALICE data challenges. The goals of these regular exercises are to test hardware and software components of the data acquisition and computing systems in realistic conditions and to execute an early integration of the overall ALICE computing infrastructure. This paper reports on the third ALICE Data Challenge (ADC III) that has been performed at CERN from January to March 2001. The data used during the ADC III are simulated physics raw data of the ALICE TPC, produced with the ALICE simulation program AliRoot. The data acquisition was based on the ALICE online framework called the ALICE Data Acquisition Test Environment (DATE) system. The data after event building were then formatted with the ROOT I/O package and a data catalogue based on MySQL was established. The Mass Storage System used during ADC III is CASTOR. Different software tools have been used to monitor the performances. DATE has demonstrated performances of more than 500 MByte/s. An aggregate data throughput of 85 MByte/s was sustained in CASTOR over several days. The total collected data amounts to 100 TBytes in 100,000 files
Vertebral osteomyelitis and native valve endocarditis due to Staphylococcus simulans: a case report
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Signatures of arithmetic simplicity in metabolic network architecture
Metabolic networks perform some of the most fundamental functions in living
cells, including energy transduction and building block biosynthesis. While
these are the best characterized networks in living systems, understanding
their evolutionary history and complex wiring constitutes one of the most
fascinating open questions in biology, intimately related to the enigma of
life's origin itself. Is the evolution of metabolism subject to general
principles, beyond the unpredictable accumulation of multiple historical
accidents? Here we search for such principles by applying to an artificial
chemical universe some of the methodologies developed for the study of genome
scale models of cellular metabolism. In particular, we use metabolic flux
constraint-based models to exhaustively search for artificial chemistry
pathways that can optimally perform an array of elementary metabolic functions.
Despite the simplicity of the model employed, we find that the ensuing pathways
display a surprisingly rich set of properties, including the existence of
autocatalytic cycles and hierarchical modules, the appearance of universally
preferable metabolites and reactions, and a logarithmic trend of pathway length
as a function of input/output molecule size. Some of these properties can be
derived analytically, borrowing methods previously used in cryptography. In
addition, by mapping biochemical networks onto a simplified carbon atom
reaction backbone, we find that several of the properties predicted by the
artificial chemistry model hold for real metabolic networks. These findings
suggest that optimality principles and arithmetic simplicity might lie beneath
some aspects of biochemical complexity
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