Polyhydroxyalkanoates (PHAs), stored as bacterial reserve materials for carbon and energy, are biodegradable substitutes to fossil fuel plastics that can be produced from renewable raw materials. ...PHAs can be produced under controlled conditions by biotechnological processes. By varying the producing strains, substrates and cosubstrates, a number of polyesters can be synthesized which differ in monomer composition. By this means, PHAs with tailored interesting physical features can be produced. All of them are completely degradable to carbon dioxide and water through natural microbiological mineralization. Consequently, neither their production nor their use or degradation have a negative ecological impact. After a historical review, possibilities for the synthesis of novel PHAs applying different micro-organisms are discussed, and pathways of PHA synthesis and degradation are shown in detail for important PHA producers. This is followed by a discussion of the physiological role of the accumulation product in different micro-organisms. Detection, analysis, and extraction methods of PHAs from microbial biomass are shown, in addition to methods for polyester characterization. Strategies for PHA production under discontinuous and continuous regimes are discussed in detail in addition to the use of different cheap carbon sources from the point of view of different PHA producing strains. An outlook on PHA production by transgenic plants closes the review.
In the fall 2016, GeantV went through a thorough community evaluation of the project status and of its strategy for sharing the R&D results with the LHC experiments and with the HEP simulation ...community in general. Following this discussion, GeantV has engaged onto an ambitious 2-year road-path aiming to deliver a beta version that has most of the final design and several performance features of the final product, partially integrated with some of the experiment's frameworks. The initial GeantV prototype has been updated to a vector-aware concurrent framework, which is able to deliver high-density floating-point computations for most of the performance-critical components such as propagation in field and physics models. Electromagnetic physics models were adapted for the specific GeantV requirements, aiming for the full demonstration of shower physics performance in the alpha release at the end of 2017. We have revisited and formalized GeantV user interfaces and helper protocols, allowing to: connect to user code, provide recipes to access efficiently MC truth and generate user data in a concurrent environment.
Recent developments in Geant4 Allison, J.; Amako, K.; Apostolakis, J. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2016, Letnik:
835, Številka:
C
Journal Article
Recenzirano
Odprti dostop
Geant4 is a software toolkit for the simulation of the passage of particles through matter. It is used by a large number of experiments and projects in a variety of application domains, including ...high energy physics, astrophysics and space science, medical physics and radiation protection. Over the past several years, major changes have been made to the toolkit in order to accommodate the needs of these user communities, and to efficiently exploit the growth of computing power made available by advances in technology. The adaptation of Geant4 to multithreading, advances in physics, detector modeling and visualization, extensions to the toolkit, including biasing and reverse Monte Carlo, and tools for physics and release validation are discussed here.
•Multithreading resulted in a smaller memory footprint and nearly linear speed-up.•Scoring options, faster geometry primitives, more versatile visualization were added.•Improved electromagnetic and hadronic models and cross sections were developed.•Reverse Monte Carlo and general biasing methods were added.•Physics validation efforts were expanded and new validation tools were added.
GEANT4 parameter tuning using Professor Elvira, V.; Fields, L.; Genser, K.L. ...
Journal of instrumentation,
02/2020, Letnik:
15, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The GEANT4 toolkit is used extensively in high energy physics to simulate the passage of particles through matter and to predict effects such as detector efficiencies and smearing. GEANT4 uses many ...underlying models to predict particle interaction kinematics, and uncertainty in these models leads to uncertainty in high energy physics measurements. The GEANT4 collaboration recently made free parameters in some models accessible through partnership with GEANT4 developers. We present a study of the impact of varying parameters in three GEANT4 hadronic physics models on agreement with thin target datasets and describe fits to these datasets using the Professor model tuning framework 1. We find that varying parameters produces substantially better agreement with some datasets, but that more degrees of freedom are required for full agreement. This work is a first step towards a common framework for propagating uncertainties in GEANT4 models to high energy physics measurements, and we outline future work required to complete that goal.
The upgraded DØ detector Abazov, V.M.; Alves, G.A.; Askew, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2006, Letnik:
565, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The DØ experiment enjoyed a very successful data-collection run at the Fermilab Tevatron collider between 1992 and 1996. Since then, the detector has been upgraded to take advantage of improvements ...to the Tevatron and to enhance its physics capabilities. We describe the new elements of the detector, including the silicon microstrip tracker, central fiber tracker, solenoidal magnet, preshower detectors, forward muon detector, and forward proton detector. The uranium/liquid-argon calorimeters and central muon detector, remaining from Run I, are discussed briefly. We also present the associated electronics, triggering, and data acquisition systems, along with the design and implementation of software specific to DØ.
Fragments of chromosomal DNA from
Alcaligenes latus DSM1124 were cloned into
Escherichia coli and transformants were screened for poly(
d(−)-3-hydroxybutyrate) P(3HB) production during excess carbon ...supply. A plasmid harboring a 5.5-kb insert of
A. latus DNA was isolated from a P(3HB)-producing bacterial colony. The insert was partially sequenced and three major open reading frames (ORFs) were found, representing the PHA synthase (
phaC),
β-ketothiolase (
phaA) and acetoacetyl-CoA reductase (
phaB) genes. They show striking homology to the
Ralstonia eutropha (formerly
Alcaligenes eutrophus)
phaC (71%),
phaA (77%) and
phaB (80%) genes, and are organized in the same way. The only major difference is the replacement of 560 nucleotides by 160 non-homologous nucleotides in the 5′ region of
phaC in
A. latus. The
phaC ORF lacks 29 amino acids at the N-terminus, compared to that of
R. eutropha, and starts with a GTG codon. The transcription start points of the operon were determined. P(3HB) production of recombinant
E. coli strains harboring the
pha operons of
A. latus DSM1124 or
R. eutropha H16 was investigated. Both operons gave rise to less than 5% P(3HB) formation during exponential growth. At the end of the growth phase, the P(3HB) content reached approximately 20% of cell dry mass. Under nitrogen-depleted conditions, the
A. latus pha genes gave rise to 50–52% P(3HB), compared to 33–38% for the
R. eutropha pha genes. No NADH oxidase activity was detectable in
A. latus, indicating an impaired respiratory pathway and a dependence on PHA synthesis for storing reduction equivalents during growth.
The data processing model for the CDF experiment is described. Data processing reconstructs events from parallel data streams taken with different combinations of physics event triggers and further ...splits the events into datasets of specialised physics interests. The design of the processing control system makes strict requirements on bookkeeping records, which trace the status of data files and event contents during processing and storage. The computing architecture was updated to meet the mass data flow of the Run II data collection, recently upgraded to a maximum rate of 40 MByte/sec. The data processing facility consists of a large cluster of Linux computers with data movement managed by the CDF data handling system to a multi-petaByte Enstore tape library. The latest processing cycle has achieved a stable speed of 35 MByte/sec (3 TByte/day). It can be readily scaled by increasing CPU and data-handling capacity as required
The Geant4 toolkit is used extensively in high energy physics to simulate the passage of particles through matter and to predict effects such as detector efficiencies and smearing. Geant4 uses many ...underlying models to predict particle interaction kinematics, and uncertainty in these models leads to uncertainty in high energy physics measurements. The Geant4 collaboration recently made free parameters in some models accessible through partnership with Geant4 developers. We present a study of the impact of varying parameters in three Geant4 hadronic physics models on agreement with thin target datasets and describe fits to these datasets using the Professor model tuning framework. We find that varying parameters produces substantially better agreement with some datasets, but that more degrees of freedom are required for full agreement. This work is a first step towards a common framework for propagating uncertainties in Geant4 models to high energy physics measurements, and we outline future work required to complete that goal.
The Mu2e experiment at Fermilab will search for the neutrinoless μ−→e− conversion in the field of an aluminum nucleus. The Mu2e data-taking plan assumes two running periods, Run I and Run II, ...separated by an approximately two-year-long shutdown. This paper presents an estimate of the expected Mu2e Run I search sensitivity and includes a detailed discussion of the background sources, uncertainties of their prediction, analysis procedures, and the optimization of the experimental sensitivity. The expected Run I 5σ discovery sensitivity is Rμe=1.2×10−15, with a total expected background of 0.11±0.03 events. In the absence of a signal, the expected upper limit is Rμe<6.2×10−16 at 90% CL. This represents a three order of magnitude improvement over the current experimental limit of Rμe<7×10−13 at 90% CL set by the SINDRUM II experiment.
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