Deployment analysis of carrier grade urban wireless mesh networks

Proceedings of: IEEE 9th Malaysia International Conference on Communications (MICC 2009), 15-17 December 2009, Kuala Lumpur (Malaysia)An optimized and cost-effective wireless mesh network (WMN) deployment for ubiquitous broadband wireless access is known to be highly dependent on a number of key factors such as backhaul solution, number of radio interfaces per node, type of radio technology, network topology/cluster, etc. The choice of network topology in turn affects the gateway-node ratio, and also the placement of gateways (GW)s and access points (AP)s. In this paper, we provide insights on the best possible upper-bound performance and inter-relationship between these key design factors under different operating conditions with respect to different target data rates per user. Next, we incorporate deployment cost analysis into the corresponding design option studies in order to provide more accurate justification on the feasibility of adopting different clustering techniques. The results from our analysis offer a general guideline or reference for network operators who intend to deploy a uniform blanket coverage using WMN especially in the urban environment.European Community's Seventh Framework ProgramPublicad

Stability of flows associated to gradient vector fields and convergence of iterated transport maps

In this paper we address the problem of stability of flows associated to a sequence of vector fields under minimal regularity requirements on the limit vector field, that is supposed to be a gradient. We apply this stability result to show the convergence of iterated compositions of optimal transport maps arising in the implicit time discretization (with respect to the Wasserstein distance) of nonlinear evolution equations of a diffusion type. Finally, we use these convergence results to study the gradient flow of a particular class of polyconvex functionals recently considered by Gangbo, Evans ans Savin. We solve some open problems raised in their paper and obtain existence and uniqueness of solutions under weaker regularity requirements and with no upper bound on the jacobian determinant of the initial datum

Plasma membrane calcium pump regulation by metabolic stress.

The plasma membrane Ca(2+)-ATPase (PMCA) is an ATP-driven pump that is critical for the maintenance of low resting [Ca(2+)](i) in all eukaryotic cells. Metabolic stress, either due to inhibition of mitochondrial or glycolytic metabolism, has the capacity to cause ATP depletion and thus inhibit PMCA activity. This has potentially fatal consequences, particularly for non-excitable cells in which the PMCA is the major Ca(2+) efflux pathway. This is because inhibition of the PMCA inevitably leads to cytosolic Ca(2+) overload and the consequent cell death. However, the relationship between metabolic stress, ATP depletion and inhibition of the PMCA is not as simple as one would have originally predicted. There is increasing evidence that metabolic stress can lead to the inhibition of PMCA activity independent of ATP or prior to substantial ATP depletion. In particular, there is evidence that the PMCA has its own glycolytic ATP supply that can fuel the PMCA in the face of impaired mitochondrial function. Moreover, membrane phospholipids, mitochondrial membrane potential, caspase/calpain cleavage and oxidative stress have all been implicated in metabolic stress-induced inhibition of the PMCA. The major focus of this review is to challenge the conventional view of ATP-dependent regulation of the PMCA and bring together some of the alternative or additional mechanisms by which metabolic stress impairs PMCA activity resulting in cytosolic Ca(2+) overload and cytotoxicity

A closed model category for (n-1)-connected spaces

For each integer n > 0, we give a distinct closed model category structure to the category of pointed spaces Top * such that the corresponding localized category Ho(Top * n) is equivalent to the standard homotopy category of (n - 1)-connected CW-complexes. The structure of closed model category given by Quillen to Top* is based on maps which induce isomorphisms on all homotopy group functors q and for any choice of base point. For each n > 0, the closed model category structure given here takes as weak equivalences those maps that for the given base point induce isomorphisms on q for q n. ©1096 American Mathematical Society

The dry land of the Lower Boteti Region in Northern Botswana and its suitability for traditional arable farming An environmental approach

SIGLETIB: RO 3338 (7) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman