Applicability of viscous hydrodynamics at RHIC

In an earlier work (arXiv:0808.0953) we established that causal Israel-Stewart viscous hydrodynamics is only accurate in RHIC applications at very low shear viscosities 4 pi eta_s / s < ~ 1.5-2. We show here that the region of applicability is significantly reduced if bulk viscosity plays a role in the dynamics.Comment: Presentation at Quark Matter 2009 - contribution to the proceedings. v2: very minor changes in text and labels in Fig.

Thermalization of gluon matter including gg<->ggg interactions

Within a pQCD inspired kinetic parton cascade we simulate the space time evolution of gluons which are produced initially in a heavy ion collision at RHIC energy. The inelastic gluonic interactions $gg \leftrightarrow ggg$ do play an important role: For various initial conditions it is found that thermalization and the close to ideal fluid dynamical behaviour sets in at very early times. Special emphasis is put on color glass condensate initial conditions and the `bottom up thermalization' scenario. Off-equilibrium $3\to 2$ processes make up the very beginning of the evolution leading to an initial decrease in gluon number and a temporary avalanche of the gluon momentum distribution to higher transversal momenta.Comment: 6 pages, 8 figures, Talk given at International Conference on Strong and Electroweak Matter (SEWM 2006), BNL, New York, May 200

A relativistic dissipative hydrodynamic description for systems including particle number changing processes

Relativistic dissipative hydrodynamic equations are extended by taking into account particle number changing processes in a gluon system, which expands in one dimension boost-invariantly. Chemical equilibration is treated by a rate equation for the particle number density based on Boltzmann equation and Grad's ansatz for the off-equilibrium particle phase space distribution. We find that not only the particle production, but also the temperature and the momentum spectra of the gluon system, obtained from the hydrodynamic calculations, are sensitive to the rates of particle number changing processes. Comparisons of the hydrodynamic calculations with the transport ones employing the parton cascade BAMPS show the inaccuracy of the rate equation at large shear viscosity to entropy density ratio. To improve the rate equation, the Grad's ansatz has to be modified beyond the second moments in momentum.Comment: 20 pages, 11 figure

Facilitating the Adoption of Public Services Using High Definition Video: The Case of Primary Education

The adoption of innovative Information and Communication Technologies (ICTs) in public services in general, and in education in particular has intensified in the last few years. Although electronic services in learning has been used in primary, secondary and higher education for some years, the use of live video technology to facilitate public services has rarely been explored before. In this paper, we focus on the adoption of high definition video-to-video (V2V) communication in the context of public sector primary education. This paper examines how V2V technology can be utilised in encouraging collaborative learning initiatives among different schools. Results of a preliminary case study are presented highlighting some of the technical and users criteria required to ensure a successful adoption of video-to-video communication in the context of education

Development of relativistic shock waves in viscous gluon matter

To investigate the formation and the propagation of relativistic shock waves in viscous gluon matter we solve the relativistic Riemann problem using a microscopic parton cascade. We demonstrate the transition from ideal to viscous shock waves by varying the shear viscosity to entropy density ratio $\eta/s$. We show that an $\eta/s$ ratio larger than 0.2 prevents the development of well-defined shock waves on time scales typical for ultrarelativistic heavy-ion collisions. These findings are confirmed by viscous hydrodynamic calculations.Comment: 4 pages, 3 figures - To appear in the conference proceedings for Quark Matter 2009, March 30 - April 4, Knoxville, Tennesse

Seismic landslide hazard mapping for Greater Vancouver, British Columbia

The lower Mainland of southwest British Columbia (BC) hosts about 3.5 million people and significant infrastructures of national importance. Southwestern BC has the highest seismic risk in Canada with significant potential to cause earthquake-induced hazards including tsunamis, liquefaction and landslides. A Cascadia mega-thrust (MW 9) earthquake is predicted to generate $75 billion Canadian dollars in losses. This damage can be resulted from ground shaking or its secondary phenomena like landslides; ground shaking during earthquakes may trigger landslides that can damage or destroy buildings, bury roads and highways and kill and injure people. In Canada, during the past century and a half, landslides have caused more fatality than all other natural hazards combined. Seismic hazard mapping for landslides integrates topographic, geotechnical and seismological information to develop the earthquake-induced slope displacements map which is indicator of seismic landslide potential. In this study we use a pseudo-probabilistic Newmark displacement analyses for regional landslide susceptibility mapping and its application will be illustrated with developing earthquake induced landslide hazard map for the quadrangle in Greater Vancouver area. The predicted displacements are assigned to the defined grids to come up with the final seismic landslide hazard map. The seismic landslide hazard map predicts very low hazard level (displacementcm) for the selected region which is in agreement with the observations in our field survey in July 2018 where no signs of deformation were recorded (e.g. cracks, settlements, previous landslides, scarps)

A case analysis of E-government service delivery through a service chain dimension

YesUnlike e-business few studies have examined how information is generated and exchanged between stakeholders in an e-government service chain to generate value for citizens. This case study applies the concept of service chains to empirically explore: a) how internal and external business activities in local government authorities (LGAs) contribute to electronic service delivery, and b) the impact that internal and external stakeholders have on these activities. The case study found that the diversity of stakeholders involved and lack of appropriate mechanisms for information exchange and collaboration are posing the biggest challenges for efficient local egovernment service delivery

Mach Cones in Viscous Matter

Employing a microscopic transport model we investigate the evolution of high energetic jets moving through a viscous medium. For the scenario of an unstoppable jet we observe a clearly strong collective behavior for a low dissipative system $\eta/s \approx 0.005$, leading to the observation of cone-like structures. Increasing the dissipation of the system to $\eta/s \approx 0.32$ the Mach Cone structure vanishes. Furthermore, we investigate jet-associated particle correlations. A double-peak structure, as observed in experimental data, is even for low-dissipative systems not supported, because of the large influence of the head shock.Comment: 4 pages, 3 figures, to appear in the conference proceedings of Hot Quarks 201

Scanning and transmission electron microscopy of the histopathological impact of Macrogyrodactylus clarii (Monogenea: Gyrodactylidae) on the gills of catfish, Clarias gariepinus

Scanning and transmission electron microscopy (TEM) were used to study the histopathological effects of the monogenean Macrogyrodactylus clarii Gussev, 1961 on the gills of the catfish Clarias gariepinus (Burchell). Suction generated during attachment created 'footprints' on host surfaces in which the host tissues were elevated above the general gill surface. 'Footprints' were bordered by four clefts caused by the muscular flaps on the anterior, lateral and posterior margins of the haptor. The hamuli points penetrate the gill tissue but no evidence was found for the insertion of the marginal hooklets. At the site of attachment, host cells adjacent to the lateral flaps often appeared compressed and widely spaced with large intercellular spaces. Desquamation of these surface epithelia was also apparent and some of the widely spaced epithelial cells had pseudopodium-like processes. Cells within the upper surface epithelial layer of the host were vacuolated and necrotic. Ruptured blood capillaries (blood spaces) in the secondary gill lamellae contained atypical compressed erythrocytes, agranular and granular leucocytes and evidence of haemorrhaging. Cells with fibrotic cytoplasm, putative phagocytes and host mucous cells were evidence of a host response at the site of parasite attachment. The possible role of these cells is discussed in relation to host resistance against infection