623 research outputs found
Dynamics of Anti-Proton -- Protons and Anti-Proton -- Nucleus Reactions
A short review of simulation results of anti-proton-proton and
anti-proton-nucleus interactions within the framework of Geant4 FTF (Fritiof)
model is presented. The model uses the main assumptions of the
Quark-Gluon-String Model or Dual Parton Model. The model assumes production and
fragmentation of quark-anti-quark and diquark-anti-diquark strings in the
mentioned interactions. Key ingredients of the model are cross sections of
string creation processes and an usage of the LUND string fragmentation
algorithm. They allow one to satisfactory describe a large set of experimental
data, especially, a strange particle production, Lambda hyperons and K mesons.Comment: 7 pages, 8 figure
Simulation of neutron production in hadron-nucleus and nucleus-nucleus interactions in Geant4
Studying experimental data obtained at ITEP [1] on neutron production in
interactions of protons with various nuclei in the energy range from 747 MeV up
to 8.1 GeV, we have found that slow neutron spectra have scaling and asymptotic
properties [2]. The spectra weakly depend on the collision energy at momenta of
projectile protons larger than 5 - 6 GeV/c. These properties are taken into
account in the Geant4 Fritiof (FTF) model. The improved FTF model describes as
well as the Geant4 Bertini model the experimental data on neutron production by
1.2 GeV and 1.6 GeV protons on targets (Fe, Pb) [3] and by 3.0 GeV protons on
various targets (Al, Fe, Pb) [4]. For neutron production in antiproton-nucleus
interactions, it was demonstrated that the FTF results are in a satisfactory
agreement with experimental data of the LEAR collaboration [5]. The FTF model
gives promising results for neutron production in nucleus - nucleus
interactions at projectile energy 1 - 2 GeV per nucleon [6]. The observed
properties allow one to predict neutron yields in the nucleus-nucleus
interactions at high and very high energies. Predictions for the NICA/MPD
experiment at JINR are presented.Comment: 6 pages, 5 figures. Contribution to Proceedings of Baldin ISHEPP XXI
Production of strange particles in hadronic interactions
The NA61/SHINE collaboration has recently published high precision data on
production of and mesons, protons, antiprotons and
hyperons in interactions at 20, 31, 40, 80 and 158 GeV/c, and in
interactions at 31 GeV/c. The collaboration also presented
experimental data on production of particles - , , ,
, and in collisions at 158 and 350
GeV/c. The collaboration has compared these data with various Monte Carlo model
calculations: UrQMD, EPOS, GiBUU, and others.
All of the models have various problems. The latest version of the FTF
(Fritiof) model of Geant4 solves most of these problems. In the FTF model, we
have improved the fragmentation of quark-gluon strings with small masses and
introduced dependencies of probabilities of strange mesons and
baryon-antibaryon pair's creation on string masses. Due to these changes, we
describe the data of the NA61/SHINE collaboration on particle production in
, and interactions.
The improved Geant4 FTF model also well reproduces experimental data on
inclusive cross sections of and production in
antiproton-proton interactions at various energies. The modified FTF model
allows one to simulate realistic processes with two particle productions -
, , , and , which will be studied in the future by the
PANDA experiment at FAIR (GSI, Germany).Comment: 10 pages, 8 figures, IWNT-37, Rila, 2018, Bulgari
Geant4 FTF model description of the latest data by the NA61/SHINE collaboration on interactions
It is shown that the Geant4 FTF model, which does not include the simulation
of the hard parton-parton scattering and the formation of the quark-gluon
plasma (QGP), describes well the NA61/SHINE data on meson distributions
for the interactions at 5.2, 6.1, 7.6 and 8.8 GeV. At higher
energies, 11.9 and 16.8 GeV, the model underestimates the
data. This is considered as an indication of the formation of QGP at higher
energies in central collisions of light and intermediate nuclei than in
collisions of heavy nuclei ( GeV).Comment: 5 pages, 2 figure
Epidemiología molecular de la tuberculosis: métodos y aplicaciones
The resurgence of tuberculosis around the world has renewed interest in understanding the epidemiology and pathogenesis of this disease. A revolutionary advance in the field of tuberculosis research has been the development of molecular techniques that permit identification and tracking of individual strains of Mycobacterium tuberculosis. With these techniques, molecular epidemiology has been established as a new discipline that adds another dimension to the classical epidemiology of tuberculosis and has increased our understanding of the transmission dynamics of M. tuberculosis. The increased epidemiological knowledge has led to discovery of inadequacies in tuberculosis control programs; this information has helped garner resources for program improvement and has highlighted the need for the continuous surveillance of tuberculosis. Additional genetic methods are being developed based on the knowledge of the genome sequence of M. tuberculosis. These simpler and less costly genotyping techniques promise to expand the application of molecular epidemiology to developing nations (where 90% of the disease burden occurs) in support of national tuberculosis programs. Furthermore, these tools permit ever more effective probes into the dynamics of transmission, the population structure, evolution and pathogenesis of M. tuberculosis.La reemergencia de la tuberculosis en el mundo ha despertado el interés en el entendimiento de la epidemiología y patogénesis de esta enfermedad. Un revolucionario avance en este campo de investigación ha sido el desarrollo de técnicas moleculares que permiten identificar y establecer la huella particular de cada cepa de M. tuberculosis. Con el uso de estas técnicas, y el establecimiento de la epidemilogia molecular como nueva disciplina se adicionó otra dimensión a la epidemiologia clásica de la tuberculosis y ha incrementado el conocimiento de la dinámica de la transmisión de M. tuberculosis dentro de una población. En el proceso han sido identificados problemas en los programas de control, lo cual ha ayudado a obtener recursos para su mejoramineto e implementación. Aún más, se ha resaltado la necesidad de continuar vigilando esta enfermedad. Otras metodologías genotípicas han sido desarrolladas a partir del conocimiento de la secuencia del genoma de M. tuberculosis. Estas metodologías genotípicas de fácil implementación y bajo costo se deben aplicar en países en vía de desarrollo, donde existe el 90% de la enfermedad, como apoyo a los programas de control de la tuberculosis. Estas herramientas permitirán conocer la dinámica de transmisión de la tuberculosis, la estructura de la población, la evolución y patogénesis de M. tuberculosis
CAP defines a second signalling pathway required for insulin-stimulated glucose transport
Insulin stimulates the transport of glucose into fat and muscle cells. Although the precise molecular mechanisms involved in this process remain uncertain, insulin initiates its actions by binding to its tyrosine kinase receptor, leading to the phosphorylation of intracellular substrates. One such substrate is the Cbl protooncogene product(1). Cbl is recruited to the insulin receptor by interaction with the adapter protein CAP, through one of three adjacent SH3 domains in the carboxy terminus of CAP(2). Upon phosphorylation of Cbl, the CAP-Cbl complex dissociates from the insulin receptor and moves to a caveolin-enriched, triton-insoluble membrane fraction(3). Here, to identify a molecular mechanism underlying this subcellular redistribution, we screened a yeast two-hybrid library using the amino-terminal region of CAP and identified the caveolar protein flotillin. Flotillin forms a ternary complex with CAP and Cbl, directing the localization of the CAP-Cbl complex to a lipid raft subdomain of the plasma membrane. Expression of the N-terminal domain of CAP in 3T3-L1 adipocytes blocks the stimulation of glucose transport by insulin, without affecting signalling events that depend on phosphatidylinositol-3-OH kinase. Thus, localization of the Cbl-CAP complex to lipid rafts generates a pathway that is crucial in the regulation of glucose uptake.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62940/1/407202a0.pd
Gel mobility shift scanning of pectin-inducible promoter from Penicillium griseoroseum reveals the involvement of a CCAAT element in the expression of a polygalacturonase gene
Previous reports have described pgg2, a polygalacturonase-encoding gene of Penicillium griseoroseum, as an attractive model for transcriptional regulation studies, due to its high expression throughout several in vitro growth conditions, even in the presence of non-inducing sugars such as sucrose. A search for regulatory motifs in the 5' upstream regulatory sequence of pgg2 identified a putative CCAAT box that could justify this expression profile. This element, located 270 bp upstream of the translational start codon, was tested as binding target for regulatory proteins. Analysis of a 170 bp promoter fragment by electrophoretic mobility shift assay (EMSA) with nuclear extracts prepared from mycelia grown in pectin-containing culture medium revealed a high mobility complex that was subsequently confirmed by analyzing it with a double-stranded oligonucleotide spanning the CCAAT motif. A substitution in the core sequence for GTAGG partially abolished the formation of specific complexes, showing the involvement of the CCAAT box in the regulation of the polygalacturonase gene studied
Heavy Flavours in Collider Experiments
Current issues in the studies of Heavy Flavours in colliders are described
with particular emphasis on experiments in which the UK is involved. Results on
charm production at HERA are examined and compared to those at the Tevatron. B
production rates at the Tevatron as well as the status of B lifetimes and
mixing in the LEP collaborations and at the Tevatron are highlighted. The
measurement of sin2beta from CDF is described as well as the most recent
results on top physics at the Tevatron
CAP interacts with cytoskeletal proteins and regulates adhesion‐mediated ERK activation and motility
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/102140/1/emboj7601406-sup-0001.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/102140/2/emboj7601406.pd
GeantV: Results from the prototype of concurrent vector particle transport simulation in HEP
Full detector simulation was among the largest CPU consumer in all CERN
experiment software stacks for the first two runs of the Large Hadron Collider
(LHC). In the early 2010's, the projections were that simulation demands would
scale linearly with luminosity increase, compensated only partially by an
increase of computing resources. The extension of fast simulation approaches to
more use cases, covering a larger fraction of the simulation budget, is only
part of the solution due to intrinsic precision limitations. The remainder
corresponds to speeding-up the simulation software by several factors, which is
out of reach using simple optimizations on the current code base. In this
context, the GeantV R&D project was launched, aiming to redesign the legacy
particle transport codes in order to make them benefit from fine-grained
parallelism features such as vectorization, but also from increased code and
data locality. This paper presents extensively the results and achievements of
this R&D, as well as the conclusions and lessons learnt from the beta
prototype.Comment: 34 pages, 26 figures, 24 table
- …