2,581 research outputs found
Education and Research in the SEENET-MTP Regional Framework for Higher Education in Physics
Southeastern European countries undergo significant changes in the
demand/supply ratio on the labour market and in the structure of professional
competences that are necessary for undertaking a professional activity. In
addition, brain-drain process and decrease of interest for a career in basic
sciences put many challenges for our community. Consequently, based on the
activity of the Southeastern European Network in Mathematical and Theoretical
Physics (SEENET MTP Network) in connecting groups and persons working in
mathematics and theoretical physics, we investigate specific qualifications
recognized in these fields in all the countries from the region, and the
related competences necessary for practicing the respective occupations. A list
of new possible occupations will be promoted for inclusion in the National
Qualifications Register for Higher Education. Finally, we analyze the vision
existing in this region on the higher education qualifications against the
European vision and experience, in particular in training of Master students,
PhD students, and senior teaching and research staff through the Network, i.e.
multilateral and bilateral programs.Comment: 6 pages, Talk given at 7th International Conference of the Balkan
Physical Union, Alexandruoplos, Greece, 9-13 September 2009. To be published
in AIP Conf.Pro
Exact Site Percolation Thresholds Using the Site-to-Bond and Star-Triangle Transformations
I construct a two-dimensional lattice on which the inhomogeneous site
percolation threshold is exactly calculable and use this result to find two
more lattices on which the site thresholds can be determined. The primary
lattice studied here, the ``martini lattice'', is a hexagonal lattice with
every second site transformed into a triangle. The site threshold of this
lattice is found to be , while the others have and
. This last solution suggests a possible approach to establishing
the bound for the hexagonal site threshold, . To derive these
results, I solve a correlated bond problem on the hexagonal lattice by use of
the star-triangle transformation and then, by a particular choice of
correlations, solve the site problem on the martini lattice.Comment: 12 pages, 10 figures. Submitted to Physical Review
Food for thought: a university-wide approach to stimulate curricular and extra-curricular ESD activity
A comparison of three dual drainage models: Shallow Water vs Local Inertial vs Diffusive Wave
This is the author accepted manuscript. The final version is available from IWA Publishing via the DOI in this record.In this study we compared three overland flow models, a full dynamic model (SWE), a local
inertial equations model (GWM), and a diffusive wave model (PDWAVE). The three models are
coupled with the same full dynamic sewer network model (SIPSON). We adopted the volume
exchange between sewer and overland flow models, and the hydraulic head and discharge
rates at the linked manholes to evaluate differences between the models. For that purpose we
developed a novel methodology based on RGB scale. The test results of a real case study show
a close agreement between coupled models in terms of the extents of flooding, depth and
volume exchanged, despite highly complex flows and geometries. The diffusive wave model
gives slightly higher maximum flood depths and a slower propagation of the flood front when
compared to the other two models. The Local inertial model shows to slight extent higher
depths downstream as the wave front is slower than the one in the fully dynamic model.
Overall, the simplified overland models can produce comparable results to fully dynamic
models with less computational costThis research is partially funded by the FCT
(Portuguese Foundation for Science and Technology) through the Doctoral Grant
SFRH/BD/81869/2011 financed through the POPH/FSE program (Programa Operacional
Potencial Humano/Fundo Social Europeu). This study had the support of the Portuguese
Foundation for Science and Technology (FCT) Project UID/MAR/04292/2013 and the UK’s
Natural Environment Research Council (NERC) Project Susceptibility of catchments to INTense
RAinfall and flooding (SINATRA, NE/K008765/1)
Transition Radiation in QCD matter
In ultrarelativistic heavy ion collisions a finite size QCD medium is
created. In this paper we compute radiative energy loss to zeroth order in
opacity by taking into account finite size effects. Transition radiation occurs
on the boundary between the finite size medium and the vacuum, and we show that
it lowers the difference between medium and vacuum zeroth order radiative
energy loss relative to the infinite size medium case. Further, in all previous
computations of light parton radiation to zeroth order in opacity, there was a
divergence caused by the fact that the energy loss is infinite in the vacuum
and finite in the QCD medium. We show that this infinite discontinuity is
naturally regulated by including the transition radiation.Comment: 21 page, 22 figure
A hybrid metal/semiconductor electron pump for quantum metrology
Electron pumps capable of delivering a current higher than 100pA with
sufficient accuracy are likely to become the direct mise en pratique of the
possible new quantum definition of the ampere. Furthermore, they are essential
for closing the quantum metrological triangle experiment which tests for
possible corrections to the quantum relations linking e and h, the electron
charge and the Planck constant, to voltage, resistance and current. We present
here single-island hybrid metal/semiconductor transistor pumps which combine
the simplicity and efficiency of Coulomb blockade in metals with the
unsurpassed performances of silicon switches. Robust and simple pumping at
650MHz and 0.5K is demonstrated. The pumped current obtained over a voltage
bias range of 1.4mV corresponds to a relative deviation of 5e-4 from the
calculated value, well within the 1.5e-3 uncertainty of the measurement setup.
Multi-charge pumping can be performed. The simple design fully integrated in an
industrial CMOS process makes it an ideal candidate for national measurement
institutes to realize and share a future quantum ampere
Deletion of Integron-Associated Gene Cassettes Impact on the Surface Properties of Vibrio rotiferianus DAT722
Background: The integron is a genetic recombination system that catalyses the acquisition of genes on mobilisable elements called gene cassettes. In Vibrio species, multiple acquired gene cassettes form a cassette array that can comprise 1-3% of the bacterial genome. Since 75% of these gene cassettes contain genes encoding proteins of uncharacterised function, how the integron has driven adaptation and evolution in Vibrio species remains largely unknown. A feature of cassette arrays is the presence of large indels. Using Vibrio rotiferianus DAT722 as a model organism, the aim of this study was to determine how large cassette deletions affect vibrio physiology with a view to improving understanding into how cassette arrays influence bacterial host adaptation and evolution. Methodology/Principal Findings: Biological assays and proteomic techniques were utilised to determine how artificially engineered deletions in the cassette array of V. rotiferianus DAT722 affected cell physiology. Multiple phenotypes were identified including changes to growth and expression of outer membrane porins/proteins and metabolic proteins. Furthermore, the deletions altered cell surface polysaccharide with Proton Nuclear Magnetic Resonance on whole cell polysaccharide identifying changes in the carbohydrate ring proton region indicating that gene cassette products may decorate host cell polysaccharide via the addition or removal of functional groups. Conclusions/Significance: From this study, it was concluded that deletion of gene cassettes had a subtle effect on bacterial metabolism but altered host surface polysaccharide. Deletion (and most likely rearrangement and acquisition) of gene cassettes may provide the bacterium with a mechanism to alter its surface properties, thus impacting on phenotypes such as biofilm formation. Biofilm formation was shown to be altered in one of the deletion mutants used in this study. Reworking surface properties may provide an advantage to the bacterium's interactions with organisms such as bacteriophage, protozoan grazers or crustaceans. © 2013 Rapa et al
The role of CD44 and ERM proteins in expression and functionality of P-glycoprotein in breast cancer cells
© 2016 by the authors. Multidrug resistance (MDR) is often attributed to the over-expression of P-glycoprotein (P-gp), which prevents the accumulation of anticancer drugs within cells by virtue of its active drug efflux capacity. We have previously described the intercellular transfer of P-gp via extracellular vesicles (EVs) and proposed the involvement of a unique protein complex in regulating this process. In this paper, we investigate the role of these mediators in the regulation of P-gp functionality and hence the acquisition of MDR following cell to cell transfer. By sequentially silencing the FERM domain-binding proteins, Ezrin, Radixin and Moesin (ERM), as well as CD44, which we also report a selective packaging in breast cancer derived EVs, we have established a role for these proteins, in particular Radixin and CD44, in influencing the P-gp-mediated MDR in whole cells. We also report for the first time the role of ERM proteins in the vesicular transfer of functional P-gp. Specifically, we demonstrate that intercellular membrane insertion is dependent on Ezrin and Moesin, whilst P-gp functionality is governed by the integrity of all ERM proteins in the recipient cell. This study identifies these candidate proteins as potential new therapeutic targets in circumventing MDR clinically
Prediction of flow around a sharp-nosed bridge pier: Influence of the Froude number and free surface variation on the flow field (article)
This is the final version. Available on open access from Taylor & Francis via the DOI in this recordThe dataset associated with this article is located in ORE at: https://doi.org/10.24378/exe.1503Author accepted manuscript replaced with published version by Caroline Huxtable on 2019-10-11This study investigates the influence of free surface variation on the velocity field using numerical simulations of flow around a
sharp-nosed pier that is representative of a typical masonry bridge pier. This study evaluates the assumption that free surface effects
are negligible at small Froude numbers by comparing the change in flow field predictions due to the use of a free surface model (i.e.
multi-phase simulation with a Volume of Fluid (VOF) model in place of a rigid-lid approximation (i.e. single phase simulation).
Results show that simulations using the VOF model are in better agreement with experimental data than those using the rigid-lid
approximation. Importantly, results show that even though the change in free surface height near the pier is small comparative to
the approach flow, it still has a significant effect on velocities in front of the pier and in the wake region, and that too at low Froude
numbers.Engineering and Physical Sciences Research Council (EPSRC
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