1,244 research outputs found
Sensitivity analysis and experimental design of a stiff signal transduction pathway model
Sensitivity analysis is normally used to analyze how sensitive a system is with respect to the change of parameters or initial conditions and is perhaps best known in systems biology via the formalism of metabolic control analysis [1, 2]. The nuclear factor B (NF-B) signalling pathway is an important cellular signalling pathway, of which protein phosphorylation is a major factor controlling the activation of further downstream events. The NF-κB proteins regulate numerous genes that play important roles in inter- and intra-cellular signalling, cellular stress responses, cell growth, survival, and apoptosis. As such, its specificity and its role in the temporal control of gene expression are of crucial physiological interest
Towards hardware acceleration of neuroevolution for multimedia processing applications on mobile devices
This paper addresses the problem of accelerating large artificial neural networks (ANN), whose topology and weights can evolve via the use of a genetic algorithm. The proposed digital hardware architecture is capable of processing any evolved network topology, whilst at the same time providing a good trade off between throughput, area and power consumption. The latter is vital for a longer battery life on mobile devices. The architecture uses multiple parallel arithmetic units in each processing element (PE). Memory partitioning and data caching are used to minimise the effects of PE pipeline stalling. A first order minimax polynomial approximation scheme, tuned via a genetic algorithm, is used for the activation function generator. Efficient arithmetic circuitry, which leverages modified Booth recoding, column compressors and carry save adders, is adopted throughout the design
Antiflow of kaons in relativistic heavy ion collisions
We compare relativistic transport model calculations to recent data on the
sideward flow of neutral strange K^0_s mesons for Au+Au collisions at 6 AGeV. A
soft nuclear equation of state is found to describe very well the positive
proton flow data measured in the same experiment. In the absence of kaon
potential, the K^0 flow pattern is similar to that of protons. The kaon flow
becomes negative if a repulsive kaon potential determined from the impulse
approximation is introduced. However, this potential underestimates the data
which exhibits larger antiflow. An excellent agreement with the data is
obtained when a relativistic scalar-vector kaon potential, that has stronger
density dependence, is used. We further find that the transverse momentum
dependence of directed and elliptic flow is quite sensitive to the kaon
potential in dense matter.Comment: 5 pages, Revtex, 4 figure
What does the rho-meson do? In-medium mass shift scenarios versus hadronic model calculations
The NA60 experiment has studied low-mass muon pair production in In-In
collisions at with unprecedented precision. With these results
there is hope that the in-medium modifications of the vector meson spectral
function can be constrained more thoroughly than before. We investigate in
particular what can be learned about collisional broadening by a hot and dense
medium and what constrains the experimental results put on in-medium mass shift
scenarios. The data show a clear indication of considerable in-medium
broadening effects but disfavor mass shift scenarios where the -meson
mass scales with the square root of the chiral condensate. Scaling scenarios
which predict at finite density a dropping of the -meson mass that is
stronger than that of the quark condensate are clearly ruled out since they are
also accompanied by a sharpening of the spectral function.Comment: Proceeding contribution, Talk given by J. Ruppert at Workshop for
Young Scientists on the Physics of Ultrarelativistic Nucleus-Nucleus
Collisions (Hot Quarks 2006), Villasimius, Sardinia, Italy, 15-20 May 2006.
To appear in EPJ
Surface Tension between Kaon Condensate and Normal Nuclear Matter Phase
We calculate for the first time the surface tension and curvature coefficient
of a first order phase transition between two possible phases of cold nuclear
matter, a normal nuclear matter phase in equilibrium with a kaon condensed
phase, at densities a few times the saturation density. We find the surface
tension is proportional to the difference in energy density between the two
phases squared. Furthermore, we show the consequences for the geometrical
structures of the mixed phase region in a neutron star.Comment: 7 pages, 5 figures (Latex
Choosing more mathematics : happiness through work?
This paper examines how A-level students construct relationships between work and happiness in their accounts of choosing mathematics and further mathematics A-level. I develop a theoretical framework that positions work and happiness as opposed, managed and working on the self and use this to examine students' dual engagement with individual practices of the self and institutional practices of school mathematics. Interviews with students acknowledge four imperatives that they use as discursive resources to position themselves as successful/unsuccessful students: you have to work, you have to not work, you have to be happy, you have to work at being happy. Tensions in these positions lead students to rework their identities or drop further mathematics. I then identify the practices of mathematics teaching that students use to explain un/happiness in work, and show how dependable mathematics and working together are constructed as 'happy objects' for students, who develop strategies for claiming control over these shapers of happiness. © 2010 British Society for Research into Learning Mathematics
The gravitationally lensed, luminous infrared galaxy IRAS F10214+4724 observed with XMM-Newton
We report on a short XMM-Newton observation of the gravitationally-lensed,
luminous infrared galaxy IRAS F10214+4724 at z=2.3. A faint X-ray source is
detected at 4 sigma. The observed 0.5-2 keV (1.7-6.6 keV in the rest-frame)
flux is 1.3e-15 erg/s/cm2 and the spectral slope in the rest-frame 1-10 keV
band is Gamma~2. These results agree with those obtained from the Chandra X-ray
Observatory, given the large uncertainties in both measurements. While possible
evidence for excess emission above 5 keV is seen, we suspect this excess might
be either spurious or not related to the infrared galaxy.Comment: 4 pages, 2 figures, New Astronomy in pres
Closed Strings with Low Harmonics and Kinks
Low-harmonic formulas for closed relativistic strings are given. General
parametrizations are presented for the addition of second- and third-harmonic
waves to the fundamental wave. The method of determination of the
parametrizations is based upon a product representation found for the finite
Fourier series of string motion in which the constraints are automatically
satisfied. The construction of strings with kinks is discussed, including
examples. A procedure is laid out for the representation of kinks that arise
from self-intersection, and subsequent intercommutation, for harmonically
parametrized cosmic strings.Comment: 39, CWRUTH-93-
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