509 research outputs found
A Hardware Implementation of Artificial Neural Network Using Field Programmable Gate Arrays
An artificial neural network algorithm is implemented using a field
programmable gate array hardware. One hidden layer is used in the feed-forward
neural network structure in order to discriminate one class of patterns from
the other class in real time. With five 8-bit input patterns, six hidden nodes,
and one 8-bit output, the implemented hardware neural network makes decision on
a set of input patterns in 11 clocks and the result is identical to what to
expect from off-line computation. This implementation may be used in level 1
hardware triggers in high energy physics experimentsComment: 13 pages, 4 figures, submitted to Nucl. Instr. Meth.
The Role of Screening Corrections in High Energy Photoproduction
The role of screening corrections, calculated using the eikonal model, is
discussed in the context of soft photoproduction. We present a comprehensive
calculation considering the total,elastic and diffractive cross sections
jointly. We examine the differences between our results and those obtained from
the supercritical Pomeron-Reggeon model with no unitarity corrections.Comment: 12 pages (Replacement due to PostScript file problem in previous
posting
Game Change: What Have We Learned? Pt. 2
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Whole genome resequencing of Botrytis cinerea isolates identifies high levels of standing diversity
How standing genetic variation within a pathogen contributes to diversity in host/pathogen interactions is poorly understood, partly because most studied pathogens are host-specific, clonally reproducing organisms which complicates genetic analysis. In contrast, Botrytis cinerea is a sexually reproducing, true haploid ascomycete that can infect a wide range of diverse plant hosts. While previous work had shown significant genomic variation between two isolates, we proceeded to assess the level and frequency of standing variation in a population of B. cinerea. To begin measuring standing genetic variation in B. cinerea, we re-sequenced the genomes of 13 different isolates and aligned them to the previously sequenced T4 reference genome. In addition one of these isolates was resequenced from four independently repeated cultures. A high level of genetic diversity was found within the 13 isolates. Within this variation, we could identify clusters of genes with major effect polymorphisms, i.e., polymorphisms that lead to a predicted functional knockout, that surrounded genes involved in controlling vegetative incompatibility. The genotype at these loci was able to partially predict the interaction of these isolates in vegetative fusion assays showing that these loci control vegetative incompatibility. This suggests that the vegetative incompatibility loci within B. cinerea are associated with regions of increased genetic diversity. The genome re-sequencing of four clones from the one isolate (Grape) that had been independently propagated over 10 years showed no detectable spontaneous mutation. This suggests that B. cinerea does not display an elevated spontaneous mutation rate. Future work will allow us to test if, and how, this diversity may be contributing to the pathogen's broad host range
FAIRMODE: A FORUM FOR AIR QUALITY MODELLING IN EUROPE
FAIRMODE (Forum for AIR quality MODelling in Europe) is an air quality modelling network that was established as a
joint initiative of the European Environment Agency (EEA) and European Commission’s Joint Research Centre (JRC). In a
common effort EEA and JRC aim at responding to the requirements of the new Air Quality Directive, with particular focus on the
introduction of modelling as a necessary tool for air quality assessment and air quality management. The main aim of the modelling
network is to bring together air quality modellers and model users in order to promote and support harmonised use of modelling for
the assessment of air quality by EU and EEA member countries. The network will thus encourage synergy – at a local, national and
European level - through the development and implementation of a common infrastructure based on best practices for reporting and
storing information relevant to air quality modelling. A major objective of the FAIRMODE initiative is to provide guidance to
present and future air quality model users in EEA’s EIONET partnership network. FAIRMODE also aims to enhance awareness of
model usefulness, reliability and accuracy through model validation and intercomparison exercises at a national or European level.
The JRC has taken on a leading role in the co-ordination of the latter activities gaining from its experience in leading the
“Eurodelta” and “CityDelta” intercomparison exercises.
A centralised web portal has been created in support of FAIRMODE, which is currently being used for internal communication
purposes of the network participants, but will also provide the means for exchange of relevant material and experiences between all
interested modellers and model users. The initial activities of the network will be organised by two main Work Groups, focusing on
the preparation of a Guidance Document for model use and on model QA/QC procedures (input data, other uncertainties)
respectively. The progress of the preparation of these documents as well as of the rest of the regular activities of the network will be
reviewed and discussed within the frame of annual Plenary meetings and Steering Committee meetings
Dynamic changes in lung microRNA profiles during the development of pulmonary hypertension due to chronic hypoxia and monocrotaline
<b>Objective</b>: MicroRNAs (miRNAs) are small noncoding RNAs that have the capacity to control protein production through binding "seed" sequences within a target mRNA. Each miRNA is capable of potentially controlling hundreds of genes. The regulation of miRNAs in the lung during the development of pulmonary arterial hypertension (PAH) is unknown.<p></p>
<b>Methods and Results</b>: We screened lung miRNA profiles in a longitudinal and crossover design during the development of PAH caused by chronic hypoxia or monocrotaline in rats. We identified reduced expression of Dicer, involved in miRNA processing, during the onset of PAH after hypoxia. MiR-22, miR-30, and let-7f were downregulated, whereas miR-322 and miR-451 were upregulated significantly during the development of PAH in both models. Differences were observed between monocrotaline and chronic hypoxia. For example, miR-21 and let-7a were significantly reduced only in monocrotaline-treated rats. MiRNAs that were significantly regulated were validated by quantitative polymerase chain reaction. By using in vitro studies, we demonstrated that hypoxia and growth factors implicated in PAH induced similar changes in miRNA expression. Furthermore, we confirmed miR-21 downregulation in human lung tissue and serum from patients with idiopathic PAH.<p></p>
<b>Conclusion</b>: Defined miRNAs are regulated during the development of PAH in rats. Therefore, miRNAs may contribute to the pathogenesis of PAH and represent a novel opportunity for therapeutic intervention.<p></p>
Increased resistance to biotrophic pathogens in the Arabidopsis constitutive induced resistance 1 mutant is EDS1 and PAD4-dependent and modulated by environmental temperature
The Arabidopsis constitutive induced resistance 1 ( cir1 ) mutant displays salicylic acid (SA)-dependent constitutive expression of defence genes and enhanced resistance to biotrophic pathogens. To further characterise the role of CIR1 in plant immunity we conducted epistasis analyses with two key components of the SA-signalling branch of the defence network, ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1) and PHYTOALEXIN DEFICIENT4 (PAD4). We demonstrate that the constitutive defence phenotypes of cir1 require both EDS1 and PAD4, indicating that CIR1 lies upstream of the EDS1-PAD4 regulatory node in the immune signalling network. In light of this finding we examined EDS1 expression in cir1 and observed increased protein, but not mRNA levels in this mutant, suggesting that CIR1 might act as a negative regulator of EDS1 via a post-transcriptional mechanism. Finally, as environmental temperature is known to influence the outcome of plant-pathogen interactions, we analysed cir1 plants grown at 18, 22 or 25°C. We found that susceptibility to Pseudomonas syringae pv. tomato ( Pst ) DC3000 is modulated by temperature in cir1 . Greatest resistance to this pathogen (relative to PR-1:LUC control plants) was observed at 18°C, while at 25°C no difference in susceptibility between cir1 and control plants was apparent. The increase in resistance to Pst DC3000 at 18°C correlated with a stunted growth phenotype, suggesting that activation of defence responses may be enhanced at lower temperatures in the cir1 mutant
High-resolution temporal profiling of transcripts during Arabidopsis leaf senescence reveals a distinct chronology of processes and regulation
Leaf senescence is an essential developmental process that impacts dramatically on crop yields and involves altered
regulation of thousands of genes and many metabolic and signaling pathways, resulting in major changes in the leaf. The
regulation of senescence is complex, and although senescence regulatory genes have been characterized, there is little
information on how these function in the global control of the process. We used microarray analysis to obtain a highresolution
time-course profile of gene expression during development of a single leaf over a 3-week period to senescence.
A complex experimental design approach and a combination of methods were used to extract high-quality replicated data
and to identify differentially expressed genes. The multiple time points enable the use of highly informative clustering to
reveal distinct time points at which signaling and metabolic pathways change. Analysis of motif enrichment, as well
as comparison of transcription factor (TF) families showing altered expression over the time course, identify clear groups
of TFs active at different stages of leaf development and senescence. These data enable connection of metabolic
processes, signaling pathways, and specific TF activity, which will underpin the development of network models to
elucidate the process of senescence
Systematics of Heavy Quark Production at HERA
We discuss heavy quark and quarkonium production in various kinematic regions
at the HERA ep collider. In contrast to fixed target experiments, collider
kinematics allows the possibility of detailed measurements of particle
production in the proton fragmentation region. One thus can study parton
correlations in the proton Fock states materialized by the virtual photon
probe. We discuss various configurations of inelastic electron-proton
scattering, including peripheral, diffractive, and deep inelastic processes. In
particular, we show that intrinsic heavy quark Fock states can be identified by
the observation of quarkonium production at large and a low mean
transverse momentum which is insensitive to the virtuality of the photon.Comment: 17 pages, postscript. To obtain a copy of this paper send e-mail to
[email protected]
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