Flow Data Collection in Large Scale Networks

In this chapter, we present flow-based network traffic monitoring of large scale networks. Continuous Internet traffic increase requires a deployment of advanced monitoring techniques to provide near real-time and long-term network visibility. Collected flow data can be further used for network behavioral analysis to indicate legitimate and malicious traffic, proving cyber threats, etc. An early warning system should integrate flow-based monitoring to ensure network situational awareness.Kapitola představuje monitorování síťového provozu v rozsáhlých počítačových sítích založené na IP tocích. Nepřetržitý růst internetového provozu vyžaduje nasazení pokročilých monitorovacích technik, které poskytují v reálném čase a dlouhodobě pohled na dění v síti. Nasbíraná data mohou dále sloužit pro analýzu chování sítě k rozlišení legitimního a škodlivého provozu, dokazování kybernetických hrozeb atd. Systém včasného varování by měl integrovat monitorování síťových toků, aby mohl poskytovat přehled o situaci na síti

Large-scale general practice in England: what can we learn from the literature?

Traditional general practice is changing. Three-quarters of practices are now working collaboratively in larger-scale organisations – albeit with varying degrees of ambition and organisational integration. Policy-makers and practitioners have high hopes for these organisations and their potential to transform services both within primary care and beyond. But can we be confident that they can live up to these expectations? This report presents findings of an extensive literature review on the subject of large-scale general practice, and contributes to a stream of work by the Nuffield Trust in this area, details of which can be found at: www.nuffieldtrust.org.uk/large-scale-general-practice

Large Scale Structure

Catalogues of galaxies, clusters of galaxies and superclusters - sources of information to study the large-scale structure of the Universe are reviewed. The power spectrum of density perturbations, and the correlation function are discussed as principal description functions which characterize the large-scale structure. Special attention is payd to the geometric interpretation of these functions, i.e. the way in which the various properties of the distribution of galaxies in systems and systems themselves are reflected in these functions. We discuss cosmological parameters which characterize general properties of the Universe: the Hubble constant, densities of various populations of the Universe, and parameters of the power spectrum of galaxies and matter.Comment: LaTex (sty files added), 24 pages, 8 PostScript figures embedded, in ``Understanding the Universe at the close of XXth Century'', ed. M. Signore, Elseview (in press

Large scale-small scale duality and cosmological constant

We study a model of quantum cosmology originating from a classical model of gravitation where a self interacting scalar field is coupled to gravity with the metric undergoing a signature transition. We show that there are dual classical signature changing solutions, one at large scales and the other at small scales. It is possible to fine-tune the physics in both scales with an infinitesimal effective cosmological constant.Comment: 10 pages, LaTeX, To appear in Phys. Lett.

Large scale GW calculations

We present GW calculations of molecules, ordered and disordered solids and interfaces, which employ an efficient contour deformation technique for frequency integration, and do not require the explicit evaluation of virtual electronic states, nor the inversion of dielectric matrices. We also present a parallel implementation of the algorithm which takes advantage of separable expressions of both the single particle Green's function and the screened Coulomb interaction. The method can be used starting from density functional theory calculations performed with semi-local or hybrid functionals. We applied the newly developed technique to GW calculations of systems of unprecedented size, including water/semiconductor interfaces with thousands of electrons

Fast Large-Scale Reionization Simulations

We present an efficient method to generate large simulations of the Epoch of Reionization (EoR) without the need for a full 3-dimensional radiative transfer code. Large dark-matter-only simulations are post-processed to produce maps of the redshifted 21cm emission from neutral hydrogen. Dark matter haloes are embedded with sources of radiation whose properties are either based on semi-analytical prescriptions or derived from hydrodynamical simulations. These sources could either be stars or power-law sources with varying spectral indices. Assuming spherical symmetry, ionized bubbles are created around these sources, whose radial ionized fraction and temperature profiles are derived from a catalogue of 1-D radiative transfer experiments. In case of overlap of these spheres, photons are conserved by redistributing them around the connected ionized regions corresponding to the spheres. The efficiency with which these maps are created allows us to span the large parameter space typically encountered in reionization simulations. We compare our results with other, more accurate, 3-D radiative transfer simulations and find excellent agreement for the redshifts and the spatial scales of interest to upcoming 21cm experiments. We generate a contiguous observational cube spanning redshift 6 to 12 and use these simulations to study the differences in the reionization histories between stars and quasars. Finally, the signal is convolved with the LOFAR beam response and its effects are analyzed and quantified. Statistics performed on this mock data set shed light on possible observational strategies for LOFAR.Comment: 18 pages, 21 figures, submitted to MNRAS For high-resolution images follow "http://www.astro.rug.nl/~thomas/eormap.pdf