49,690 research outputs found
Domains in Infinite Jets: C-Spectral Sequence
Domains in infinite jets present the simplest class of diffieties with
boundary. In this note some basic elements of geometry of these domains are
introduced and an analogue of the C-spectral sequence in this context is
studied. This, in particular, allows cohomological interpretation and analysis
of initial data, boundary conditions, etc, for general partial differential
equations and of transversality conditions in calculus of variations. This kind
applications and extensions to arbitrary diffieties will be considered in
subsequent publications.Comment: 7 pages; no proofs give
Finite size scaling of the bayesian perceptron
We study numerically the properties of the bayesian perceptron through a
gradient descent on the optimal cost function. The theoretical distribution of
stabilities is deduced. It predicts that the optimal generalizer lies close to
the boundary of the space of (error-free) solutions. The numerical simulations
are in good agreement with the theoretical distribution. The extrapolation of
the generalization error to infinite input space size agrees with the
theoretical results. Finite size corrections are negative and exhibit two
different scaling regimes, depending on the training set size. The variance of
the generalization error vanishes for confirming the
property of self-averaging.Comment: RevTeX, 7 pages, 7 figures, submitted to Phys. Rev.
Experimental and analytical study of cracks under biaxial fatigue
Most mechanical components experience multi-axial cyclic loading conditions during service.
Experimental analysis of fatigue cracks under such conditions is not easy and most works tend to focus more
on the simpler but less realistic case of uni-axial loading. Consequently, there are many uncertainties related to
the load sequence effect that are now well known and are not normally incorporated into the growth models.
The current work presents a new methodology for evaluating overload effect in biaxial fatigue cracks. The
methodology includes evaluation of mixed-mode (KI and KII) stress intensity factor and the Crack Opening
Displacement for samples with and without overload cycle under biaxial loading. The methodology is tested
under a range of crack lengths. All crack-tip information is obtained with a hybrid methodology that combines
experimental full-field digital image correlation data and Williams' elastic model describing the crack-tip field.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
TiO2 surfaces support neuron growth during electric field stimulation
The authors are grateful to Francisco Almendros and Ismael Santamaría for help in preparation of the TiO2 substrates. We acknowledge the European Project NERBIOS (NEST/STREP (FP6), 028473-2) for financial support. Maria Canillas acknowledges the JAE-CSIC program of her PhD scholarship. Berta Moreno acknowledges the Fondo Social Europeo and the CSIC for the funding of her JAE Doc contract. Ann Rajnicek acknowledges financial support from The Development Trust at the University of Aberdeen to the Aberdeen Spinal Research Group, including support from the Scottish Rugby Union.Peer reviewedPostprin
Predicting spinor condensate dynamics from simple principles
We study the spin dynamics of quasi-one-dimensional F=1 condensates both at
zero and finite temperatures for arbitrary initial spin configurations. The
rich dynamical evolution exhibited by these non-linear systems is explained by
surprisingly simple principles: minimization of energy at zero temperature, and
maximization of entropy at high temperature. Our analytical results for the
homogeneous case are corroborated by numerical simulations for confined
condensates in a wide variety of initial conditions. These predictions compare
qualitatively well with recent experimental observations and can, therefore,
serve as a guidance for on-going experiments.Comment: 4 pages, 2 figures. v3: matches version appeared in PR
First Disk-Resolved Millimeter Observations Of Io's Surface And SO2 Atmosphere
Aims. In spite of considerable progress in the last two decades, Io's atmosphere remains poorly understood. The goal of this work is to improve our understanding of its spatial distribution, temperature and dynamics. Methods. We present millimeter observations of Io's surface and SO2 atmosphere at 1.4 mm obtained with the IRAM Plateau de Bure Interferometer in January-February 2005. With a synthesized beam of 0.5 x 1.5 '', these observations resolve Io's similar to 1.0 '' disk in the longitudinal/local time direction, and sample the leading and trailing hemispheres of Io. Results. The measured continuum total flux and visibilities show that continuum radiation originates from a depth of at least 1 cm in Io's subsurface. On both the leading and trailing sides, emission in the SO2 216.643 GHz line appears spatially narrower than the continuum, and suggests that the atmosphere covers similar to 80% of the surface on the leading side and similar to 60% on the trailing. On the leading side, disk-resolved spectra yield Doppler shift measurements, indicating a beam-integrated limb-to-limb velocity difference of 330 +/-3 100 m/s in the prograde direction. Such a flow allows an improved fit of disk-averaged SO2 spectra, but its origin remains to be understood. Mean gas temperatures are in the range 130-180 K, in agreement with estimates from IR measurements, and with a tendency for higher trailing vs leading side gas temperatures. On the basis of realistic plume models, we find that the contribution of isolated volcanic plumes to the SO2 emission is small.Astronom
- …