676 research outputs found
Generating functional analysis of complex formation and dissociation in large protein interaction networks
We analyze large systems of interacting proteins, using techniques from the
non-equilibrium statistical mechanics of disordered many-particle systems.
Apart from protein production and removal, the most relevant microscopic
processes in the proteome are complex formation and dissociation, and the
microscopic degrees of freedom are the evolving concentrations of unbound
proteins (in multiple post-translational states) and of protein complexes. Here
we only include dimer-complexes, for mathematical simplicity, and we draw the
network that describes which proteins are reaction partners from an ensemble of
random graphs with an arbitrary degree distribution. We show how generating
functional analysis methods can be used successfully to derive closed equations
for dynamical order parameters, representing an exact macroscopic description
of the complex formation and dissociation dynamics in the infinite system
limit. We end this paper with a discussion of the possible routes towards
solving the nontrivial order parameter equations, either exactly (in specific
limits) or approximately.Comment: 14 pages, to be published in Proc of IW-SMI-2009 in Kyoto (Journal of
Phys Conference Series
Tailored graph ensembles as proxies or null models for real networks I: tools for quantifying structure
We study the tailoring of structured random graph ensembles to real networks,
with the objective of generating precise and practical mathematical tools for
quantifying and comparing network topologies macroscopically, beyond the level
of degree statistics. Our family of ensembles can produce graphs with any
prescribed degree distribution and any degree-degree correlation function, its
control parameters can be calculated fully analytically, and as a result we can
calculate (asymptotically) formulae for entropies and complexities, and for
information-theoretic distances between networks, expressed directly and
explicitly in terms of their measured degree distribution and degree
correlations.Comment: 25 pages, 3 figure
Diffusion dynamics on multiplex networks
We study the time scales associated to diffusion processes that take place on
multiplex networks, i.e. on a set of networks linked through interconnected
layers. To this end, we propose the construction of a supra-Laplacian matrix,
which consists of a dimensional lifting of the Laplacian matrix of each layer
of the multiplex network. We use perturbative analysis to reveal analytically
the structure of eigenvectors and eigenvalues of the complete network in terms
of the spectral properties of the individual layers. The spectrum of the
supra-Laplacian allows us to understand the physics of diffusion-like processes
on top of multiplex networks.Comment: 6 Pages including supplemental material. To appear in Physical Review
Letter
Multipactor radiation analysis within a waveguide region based on a frequency-domain representation of the dynamics of charged particles
[EN] A technique for the accurate computation of the electromagnetic fields radiated by a charged particle moving within a parallel-plate waveguide is presented. Based on a transformation of the time-varying current density of the particle into a time-harmonic current density, this technique allows the evaluation of the radiated electromagnetic fields both in the frequency and time domains, as well as in the near- and far-field regions. For this purpose, several accelerated versions of the parallel-plate Green's function in the frequency domain have been considered. The theory has been successfully applied to the multipactor discharge occurring within a two metal-plates region. The proposed formulation has been tested with a particle-in-cell code based on the finite-difference time-domain method, obtaining good agreement.The authors would like to thank ESA/ESTEC for having funded this research activity through the Contract "RF Breakdown in Multicarrier Systems" (Contract No. 19918/06/NL/GLC).Gimeno, B.; Sorolla, E.; Anza, S.; Vicente, C.; Gil, J.; Pérez, AM.; Boria Esbert, VE.... (2009). Multipactor radiation analysis within a waveguide region based on a frequency-domain representation of the dynamics of charged particles. Physical review. E, Statistical, nonlinear, and soft matter physics. 79(4):1-9. https://doi.org/10.1103/PhysRevE.79.046604S19794Figueroa, H., Gai, W., Konecny, R., Norem, J., Ruggiero, A., Schoessow, P., & Simpson, J. (1988). Direct Measurement of Beam-Induced Fields in Accelerating Structures. Physical Review Letters, 60(21), 2144-2147. doi:10.1103/physrevlett.60.2144Ng, K.-Y. (1990). Wake fields in a dielectric-lined waveguide. Physical Review D, 42(5), 1819-1828. doi:10.1103/physrevd.42.1819Rosing, M., & Gai, W. (1990). Longitudinal- and transverse-wake-field effects in dielectric structures. Physical Review D, 42(5), 1829-1834. doi:10.1103/physrevd.42.1829Gai, W., Kanareykin, A. D., Kustov, A. L., & Simpson, J. (1997). Numerical simulations of intense charged-particle beam propagation in a dielectric wake-field accelerator. Physical Review E, 55(3), 3481-3488. doi:10.1103/physreve.55.3481Burov, A., & Danilov, V. (1999). Suppression of Transverse Bunch Instabilities by Asymmetries in the Chamber Geometry. Physical Review Letters, 82(11), 2286-2289. doi:10.1103/physrevlett.82.2286Xiao, L., Gai, W., & Sun, X. (2001). Field analysis of a dielectric-loaded rectangular waveguide accelerating structure. Physical Review E, 65(1). doi:10.1103/physreve.65.016505Jing, C., Liu, W., Xiao, L., Gai, W., Schoessow, P., & Wong, T. (2003). Dipole-mode wakefields in dielectric-loaded rectangular waveguide accelerating structures. Physical Review E, 68(1). doi:10.1103/physreve.68.016502Stupakov, G., Bane, K. L. F., & Zagorodnov, I. (2007). Optical approximation in the theory of geometric impedance. Physical Review Special Topics - Accelerators and Beams, 10(5). doi:10.1103/physrevstab.10.054401Hatch, A. J., & Williams, H. B. (1954). The Secondary Electron Resonance Mechanism of Low‐Pressure High‐Frequency Gas Breakdown. Journal of Applied Physics, 25(4), 417-423. doi:10.1063/1.1721656Hatch, A. J., & Williams, H. B. (1958). Multipacting Modes of High-Frequency Gaseous Breakdown. Physical Review, 112(3), 681-685. doi:10.1103/physrev.112.681Vaughan, J. R. M. (1988). Multipactor. IEEE Transactions on Electron Devices, 35(7), 1172-1180. doi:10.1109/16.3387Gilardini, A. L. (1995). Multipacting discharges: Constant‐ktheory and simulation results. Journal of Applied Physics, 78(2), 783-795. doi:10.1063/1.360336Riyopoulos, S. (1997). Multipactor saturation due to space-charge-induced debunching. Physics of Plasmas, 4(5), 1448-1462. doi:10.1063/1.872319Kryazhev, A., Buyanova, M., Semenov, V., Anderson, D., Lisak, M., Puech, J., … Sombrin, J. (2002). Hybrid resonant modes of two-sided multipactor and transition to the polyphase regime. Physics of Plasmas, 9(11), 4736-4743. doi:10.1063/1.1514969Udiljak, R., Anderson, D., Ingvarson, P., Jordan, U., Jostell, U., Lapierre, L., … Sombrin, J. (2003). New method for detection of multipaction. IEEE Transactions on Plasma Science, 31(3), 396-404. doi:10.1109/tps.2003.811646De Lara, J., Perez, F., Alfonseca, M., Galan, L., Montero, I., Roman, E., & Garcia-Baquero, D. R. (2006). Multipactor prediction for on-board spacecraft RF equipment with the MEST software tool. IEEE Transactions on Plasma Science, 34(2), 476-484. doi:10.1109/tps.2006.872450Torregrosa, G., Coves, A., Vicente, C. P., Perez, A. M., Gimeno, B., & Boria, V. E. (2006). Time evolution of an electron discharge in a parallel-plate dielectric-loaded waveguide. IEEE Electron Device Letters, 27(7), 619-621. doi:10.1109/led.2006.877284Udiljak, R., Anderson, D., Lisak, M., Semenov, V. E., & Puech, J. (2007). Multipactor in a coaxial transmission line. I. Analytical study. Physics of Plasmas, 14(3), 033508. doi:10.1063/1.2710464Semenov, V. E., Zharova, N., Udiljak, R., Anderson, D., Lisak, M., & Puech, J. (2007). Multipactor in a coaxial transmission line. II. Particle-in-cell simulations. Physics of Plasmas, 14(3), 033509. doi:10.1063/1.2710466Anza, S., Vicente, C., Gimeno, B., Boria, V. E., & Armendáriz, J. (2007). Long-term multipactor discharge in multicarrier systems. Physics of Plasmas, 14(8), 082112. doi:10.1063/1.2768019Udiljak, R., Anderson, D., Lisak, M., Puech, J., & Semenov, V. E. (2007). Multipactor in a Waveguide Iris. IEEE Transactions on Plasma Science, 35(2), 388-395. doi:10.1109/tps.2007.892737Burton, R. J., de Jong, M. S., & Funk, L. W. (1991). Vacuum and multipactor performance of the hadron electron ring accelerator 52 MHz cavities. Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 9(3), 2081-2084. doi:10.1116/1.577417Yamaguchi, S., Saito, Y., Anami, S., & Michizono, S. (1992). Trajectory simulation of multipactoring electrons in an S-band pillbox RF window. IEEE Transactions on Nuclear Science, 39(2), 278-282. doi:10.1109/23.277497Kishek, R., & Lau, Y. Y. (1995). Interaction of Multipactor Discharge and rf Circuit. Physical Review Letters, 75(6), 1218-1221. doi:10.1103/physrevlett.75.1218Lay-Kee Ang, Lau, Y. Y., Kishek, R. A., & Gilgenbach, R. M. (1998). Power deposited on a dielectric by multipactor. IEEE Transactions on Plasma Science, 26(3), 290-295. doi:10.1109/27.700756Kishek, R. A., Lau, Y. Y., Ang, L. K., Valfells, A., & Gilgenbach, R. M. (1998). Multipactor discharge on metals and dielectrics: Historical review and recent theories. Physics of Plasmas, 5(5), 2120-2126. doi:10.1063/1.872883Neuber, A., Hemmert, D., Krompholz, H., Hatfield, L., & Kristiansen, M. (1999). Initiation of high power microwave dielectric interface breakdown. Journal of Applied Physics, 86(3), 1724-1728. doi:10.1063/1.370953Chojnacki, E. (2000). Simulations of a multipactor-inhibited waveguide geometry. Physical Review Special Topics - Accelerators and Beams, 3(3). doi:10.1103/physrevstab.3.032001Cimino, R., Collins, I. R., Furman, M. A., Pivi, M., Ruggiero, F., Rumolo, G., & Zimmermann, F. (2004). Can Low-Energy Electrons Affect High-Energy Physics Accelerators? Physical Review Letters, 93(1). doi:10.1103/physrevlett.93.014801Abe, T., Kageyama, T., Akai, K., Ebihara, K., Sakai, H., & Takeuchi, Y. (2006). Multipactoring zone map of an rf input coupler and its application to high beam current storage rings. Physical Review Special Topics - Accelerators and Beams, 9(6). doi:10.1103/physrevstab.9.062002Sorolla, E., Anza, S., Gimeno, B., Perez, A. M. P., Vicente, C., Gil, J., … Boria, V. E. (2008). An Analytical Model to Evaluate the Radiated Power Spectrum of a Multipactor Discharge in a Parallel-Plate Region. IEEE Transactions on Electron Devices, 55(8), 2252-2258. doi:10.1109/ted.2008.926271Harrington, R. F. (2001). Time-Harmonic Electromagnetic Fields. doi:10.1109/9780470546710Hanson, G. W., & Yakovlev, A. B. (2002). Operator Theory for Electromagnetics. doi:10.1007/978-1-4757-3679-3Ewald, P. P. (1921). Die Berechnung optischer und elektrostatischer Gitterpotentiale. Annalen der Physik, 369(3), 253-287. doi:10.1002/andp.19213690304Myun-Joo Park, & Sangwook Nam. (1998). Rapid summation of the Green’s function for the rectangular waveguide. IEEE Transactions on Microwave Theory and Techniques, 46(12), 2164-2166. doi:10.1109/22.739301Capolino, F., Wilton, D. R., & Johnson, W. A. (2005). Efficient computation of the 2-D Green’s function for 1-D periodic structures using the Ewald method. IEEE Transactions on Antennas and Propagation, 53(9), 2977-2984. doi:10.1109/tap.2005.854556Kustepeli, A., & Martin, A. Q. (2000). On the splitting parameter in the Ewald method. IEEE Microwave and Guided Wave Letters, 10(5), 168-170. doi:10.1109/75.85036
Spectral density of random graphs with topological constraints
The spectral density of random graphs with topological constraints is
analysed using the replica method. We consider graph ensembles featuring
generalised degree-degree correlations, as well as those with a community
structure. In each case an exact solution is found for the spectral density in
the form of consistency equations depending on the statistical properties of
the graph ensemble in question. We highlight the effect of these topological
constraints on the resulting spectral density.Comment: 24 pages, 6 figure
Spin models on random graphs with controlled topologies beyond degree constraints
We study Ising spin models on finitely connected random interaction graphs
which are drawn from an ensemble in which not only the degree distribution
can be chosen arbitrarily, but which allows for further fine-tuning of
the topology via preferential attachment of edges on the basis of an arbitrary
function Q(k,k') of the degrees of the vertices involved. We solve these models
using finite connectivity equilibrium replica theory, within the replica
symmetric ansatz. In our ensemble of graphs, phase diagrams of the spin system
are found to depend no longer only on the chosen degree distribution, but also
on the choice made for Q(k,k'). The increased ability to control interaction
topology in solvable models beyond prescribing only the degree distribution of
the interaction graph enables a more accurate modeling of real-world
interacting particle systems by spin systems on suitably defined random graphs.Comment: 21 pages, 4 figures, submitted to J Phys
A school-based motivational intervention to promote physical activity from a self-determination theory perspective
This study analyzed the effects of a multidimensional intervention to promote physical activity (PA) in school, based on self-determination theory. The study involved 88 students, aged between 14 and 17 years, who were divided into a control group (n = 59) and an experimental group (n = 29). In the experimental group, a 6-month intervention was conducted, applying a teaching unit of fitness and health in physical education (PE) classes, an extracurricular program of healthy PA, and meetings with families. Questionnaires were administered to measure different motivational variables and PA levels at four time points. Significant differences were found in favor of the experimental group in parental and peer autonomy support; integrated regulation in PE; autonomy, intrinsic and identified regulation in leisure-time PA; moderate, hard, and very hard PA; and physical self-worth. Motivational effects were maintained over time but the effects on PA levels disappeared at 6 month
36th Cordoba Guitar Festival: Spectator Analysis Using Structural Equation Modelling (SEM)
The Cordoba Guitar Festival is one of the most important cultural events in Spain. This article analyses the musical preferences, satisfaction, attitudinal loyalty, and behavioural loyalty of spectators who attended the 36th festival held in July 2016, as well as the festival’s economic impact on the city. These characteristics of the public give rise to the four hypotheses of this study. To achieve this aim, a structural equation model (SEM) was used. The results −χ2 = 27.79, with the p-value found to be p = P (χ2 ≥ 27.79) = 0.224—show the goodness-of-fit of the model and indicate that the observed data do fit the expected dataset. The results therefore allow us to accept the proposed hypotheses concerning the influence of different latent factors, such as musical preferences, loyalty, and satisfaction with the festival. This is the main focus with which the present study has been written. Regarding the economic impact, the Festival raised 1.2 million euros, that is, slightly more than 73,000 euros per day. The amount, although not very high, is important as additional income for the city. The conclusions show the need to consider the preferences of the spectator as an essential tool to enable the continuation and longevity of the Cordoba Guitar Festival—an important cultural destination
Physical activity quantification in elder women
Cuantificación de la actividad física en mujeres mayores
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