Overlapping Schwarz methods for Fekete and Gauss-Lobatto spectral elements

The classical overlapping Schwarz algorithm is here extended to the triangular/tetrahedral spectral element (TSEM) discretization of elliptic problems. This discretization, based on Fekete nodes, is a generalization to nontensorial elements of the tensorial Gauss–Lobatto–Legendre quadrilateral spectral elements (QSEM). The overlapping Schwarz preconditioners are based on partitioning the domain of the problem into overlapping subdomains, solving local problems on these subdomains, and solving an additional coarse problem associated with either the subdomain mesh or the spectral element mesh. The overlap size is generous, i.e., one element wide, in the TSEM case, while it is minimal or variable in the QSEM case. The results of several numerical experiments show that the convergence rate of the proposed preconditioning algorithm is independent of the number of subdomains $N$ and the spectral degree $p$ in case of generous overlap; otherwise it depends inversely on the overlap size. The proposed preconditioners are also robust with respect to arbitrary jumps of the coefficients of the elliptic operator across subdomains

Technologies and techniques offering new interpretations of the landscape evolution

The need for specific documents in terms of environment and landscape has its origin in late eighties, when in Italy both at European and Regional level several dispositions related to the improvement of the landscape quality came out to guarantee the compatibility of territorial transformations. Within this traditional context, how innovative, mainly BIM-oriented, technologies can be useful in offering new ways of interpretation for the landscape planning and safeguarding? The aim of the present work is to read and translate landscape elements using digital BIM-oriented platforms, in order to develop an optimized procedure to collect/organize/implement data and define guidelines for landscape and visual impact assessment; furthermore, the aim is to understand the limits that are still present within available tools. After having read the features of the territory another key point is the creation of digital parametric libraries to represent environmental mitigation works. As far as visual mitigation works are concerned, visibility analysis of the infrastructure is possible through Virtual and Mixed Reality. Once the modeling of specific components is performed, they can be located within the contextual model, where outputs related to the “whole” can be extracted and updated afterwards. New digital technologies and techniques undoubtedly offer new interpretation scenarios of the landscape evolution; nevertheless, there are still strong limits related to the interactions among these tools. The present work provides a valid methodology to involve landscape and urban planning in the BIM process. The research also proposes a series of BIM oriented tools and software to develop a typical output (landscape report) required during the design process, useful for landscape architects

Influence of a nonforage diet on plasma leptin in dairy goats throughout lactation

The aim of this study was to compare the plasma level of leptin in lactating goats fed a traditional silage-based diet or a totally free forage diet, throughout lactation and during the pre and post-feeding state. Conclusions: The opposite trend in the pattern of diet effects on DMI and plasma leptin, both in pre- and postfeeding state, induces to retain that in goats throughout lactation the levels of leptin can be related to DM intake, as Barb (1999) proposed in other animal models. Finally, it is interesting to note that also in lactating goats, as in other species, plasma leptin level increased during the post-feeding phase

The Λ\LambdaCDM growth rate of structure revisited

We re-examine the growth index of the concordance $\Lambda$ cosmology in the light of the latest 6dF and {\em WiggleZ} data. In particular, we investigate five different models for the growth index $\gamma$, by comparing their cosmological evolution using observational data of the growth rate of structure formation at different redshifts. Performing a joint likelihood analysis of the recent supernovae type Ia data, the Cosmic Microwave Background shift parameter, Baryonic Acoustic Oscillations and the growth rate data, we determine the free parameters of the $\gamma(z)$ parametrizations and we statistically quantify their ability to represent the observations. We find that the addition of the 6dF and {\em WiggleZ} growth data in the likelihood analysis improves significantly the statistical results. As an example, considering a constant growth index we find $\Omega_{m0}=0.273\pm 0.011$ and $\gamma=0.586^{+0.079}_{-0.074}$.Comment: 8 pages, 5 figures, Accepted for publication by International J. of Modern Physics D (IJMPD). arXiv admin note: substantial text overlap with arXiv:1203.672

The Potential of Visible and Far-Red to Near-Infrared Light in Glaucoma Neuroprotection

Alternative treatment strategies are necessary to reduce the severity of glaucoma, a group of eye conditions that progressively damage the optic nerve and impair vision. The aim of this review is to gain insight into potentially exploitable molecular mechanisms to slow down the death of retinal ganglion cells (RGCs), a fundamental element in the pathophysiology of all forms of glaucoma, and to stimulate adult optic nerve repair. For this purpose, we focus our analysis on both visible and far-red to near-infrared light photobiomodulation (PBM) as phototherapeutic agents, which were recently proposed in RGCs, and on the nerve lamina region neural progenitor cell (ONLR-NPC) niche. Both are suggested as potential strategies in glaucoma neuroprotection. We discuss the impact of beneficial molecular effects of PBM on both mitochondrial derangement and the alteration of ion fluxes that are considered important causes of RGC damage, as well as on the stimulation of progenitor cells. We suggest these are the most promising approaches to prevent excessive neuronal cell loss. We describe the experimental evidence supporting the validity of PBM therapy which, despite being a safe, non-invasive, inexpensive, and easy to administer procedure, has not yet been fully explored in the clinical practice of glaucoma treatment

Parallel preconditioners and high order elements for microwave imaging

This paper combines the use of high order finite element methods with parallel preconditioners of domain decomposition type for solving electromagnetic problems arising from brain microwave imaging. The numerical algorithms involved in such complex imaging systems are computationally expensive since they require solving the direct problem of Maxwell's equations several times. Moreover, wave propagation problems in the high frequency regime are challenging because a sufficiently high number of unknowns is required to accurately represent the solution. In order to use these algorithms in practice for brain stroke diagnosis, running time should be reasonable. The method presented in this paper, coupling high order finite elements and parallel preconditioners, makes it possible to reduce the overall computational cost and simulation time while maintaining accuracy

The cluster gas mass fraction as a cosmological probe: a revised study

(Abriged) We present the analysis of the baryonic content of 52 X-ray luminous galaxy clusters observed with Chandra in the redshift range 0.3-1.273. We use the deprojected X-ray surface brightness profiles and the measured values of the gas temperature to recover the gas and total mass profiles. By assuming that galaxy clusters are representative of the cosmic baryon budget, the distribution of the cluster baryon fraction in the hottest (T> 4 keV) systems as a function of redshift is used to constrain the cosmological parameters. We discuss how our constraints are affected by several systematics, namely the isothermality, the assumed baryon fraction in stars, the depletion parameter and the sample selection. By using only the cluster baryon fraction as a proxy for the cosmological parameters, we obtain that Omega is very well constrained at the value of 0.35 with a relative statistical uncertainty of 11% (1 sigma level; w=-1) and a further systematic error of about (-6,+7)%. On the other hand, constraints on Lambda (without the prior of flat geometry) and w (using the prior of flat geometry) are definitely weaker due to the presence of larger statistical and systematic uncertainties (of the order of 40 per cent on Lambda and larger than 50 per cent on w). If the WMAP 5-year best-fit results are assumed to fix the cosmological parameters, we limit the contributions expected from non-thermal pressure support and ICM clumpiness to be lower than about 10 per cent, leaving also room to accommodate baryons not accounted for either in the X-ray emitting plasma or in stars of the order of 18 per cent of the total cluster baryon budget.Comment: A&A in press. Accepted on March 28, 2009. Revised to match version in prin

Mortar FEs on Overlapping Meshes : Application to Magnetodynamics

Abstract The finite element (FE) method is frequently used in magnetodynamics as well suited to treat problems with complex geometries while keeping a simplicity in the implementation. However, some modelisations, as in eddy current (EC) non destructive testing (NDT), present the particularity to have moving parts. A global remeshing can be necessary which causes expensive CPU time. Domain decomposition methods allowing to take into account the movement without having to remesh the whole computational domain. The mortar element method (MEM), a variational non-conforming domain decomposition approach [1] offers attractive advantages in terms of flexibility and accuracy. In its original version for non-overlapping subdomains, the information is transferred through the skeleton of the decomposition by means of a suitable L 2 -projection of the field trace from the master to the slave subdomains. A MEM with overlapping subdomains has been proposed to coupled a global scalar potential defined everywhere in the considered domain and a local vector potential defined only in (possibly moving) conductor

Gravitational redshift of galaxies in clusters as predicted by general relativity

The theoretical framework of cosmology is mainly defined by gravity, of which general relativity is the current model. Recent tests of general relativity within the \Lambda Cold Dark Matter (CDM) model have found a concordance between predictions and the observations of the growth rate and clustering of the cosmic web. General relativity has not hitherto been tested on cosmological scales independent of the assumptions of the \Lambda CDM model. Here we report observation of the gravitational redshift of light coming from galaxies in clusters at the 99 per cent confidence level, based upon archival data. The measurement agrees with the predictions of general relativity and its modification created to explain cosmic acceleration without the need for dark energy (f(R) theory), but is inconsistent with alternative models designed to avoid the presence of dark matter.Comment: Published in Nature issued on 29 September 2011. This version includes the Letter published there as well as the Supplementary Information. 23 pages, 7 figure