Developing new techniques for modelling crowd movement

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Multi-GeV Neutrino Emission from Magnetized Gamma Ray Bursts

We investigate the expected neutrino emissivity from nuclear collisions in magnetically dominated collisional models of gamma-ray bursts, motivated by recent observational and theoretical developments. The results indicate that significant multi-GeV neutrino fluxes are expected for model parameter values which are typical of electromagnetically detected bursts. We show that for detecting at least one muon event in Icecube and its Deep Core sub-array, a single burst must be near the high end of the luminosity function and at a redshift $z\lesssim 0.2$. We also calculate the luminosity and distance ranges that can generate $0.01-1$ muon events per GRB in the same detectors, which may be of interest if simultaneously detected electromagnetically, or if measured with future extensions of Icecube or other neutrino detectors with larger effective volume and better sensitivity.Comment: 12 pages, 7 figures, accepted version for Phys.Rev.

Implementation of a Blowing Boundary Condition in the LAURA Code

Preliminary steps toward modeling a coupled ablation problem using a finite-volume Navier-Stokes code (LAURA) are presented in this paper. Implementation of a surface boundary condition with mass transfer (blowing) is described followed by verification and validation through comparisons with analytic results and experimental data. Application of the code to a carbon-nosetip ablation problem is demonstrated and the results are compared with previously published data. It is concluded that the code and coupled procedure are suitable to support further ablation analyses and studies

Restoring civic values to the news media ecology

The emergence of converged digital media platforms has seen a proliferation of new services, but also a disruption to value chains and business models, especially in a small, highly deregulated media market like New Zealand’s. Although consumer choice has expanded in some respects (e.g. subscriber video on demand via smart tablets), this does not fundamentally alter the information needs of citizens if they are to participate in a democratic society. Although digital media also provide spaces for citizen journalism and informed blogging, these complement, rather than replace, mainstream news production.&nbsp

The observable effects of a photospheric component on GRB's and XRF's prompt emission spectrum

A thermal radiative component is likely to accompany the first stages of the prompt emission of Gamma-ray bursts (GRB's) and X-ray flashes (XRF's). We analyze the effect of such a component on the observable spectrum, assuming that the observable effects are due to a dissipation process occurring below or near the thermal photosphere. We consider both the internal shock model and a 'slow heating' model as possible dissipation mechanisms. For comparable energy densities in the thermal and the leptonic component, the dominant emission mechanism is Compton scattering. This leads to a nearly flat energy spectrum (\nu F_\nu \propto \nu^0) above the thermal peak at ~10-100 keV and below 10-100 MeV, for a wide range of optical depths 0.03 <~ \tau_{\gamma e} <~ 100, regardless of the details of the dissipation mechanism or the strength of the magnetic field. At lower energies steep slopes are expected, while above 100 MeV the spectrum depends on the details of the dissipation process. For higher values of the optical depth, a Wien peak is formed at 100 keV - 1 MeV, and no higher energy component exists. For any value of \tau_{\gamma e}, the number of pairs produced does not exceed the baryon related electrons by a factor larger than a few. We conclude that dissipation near the thermal photosphere can naturally explain both the steep slopes observed at low energies and a flat spectrum above 10 keV, thus providing an alternative scenario to the optically thin synchrotron - SSC model.Comment: Discussion added on the results of Baring & Braby (2004); Accepted for publication in Ap.

Temperature Dependence of Blue Phosphorescent Cyclometalated Ir(III) Complexes

The photophysical properties for a series of facial (fac) cyclometalated Ir(III) complexes (fac-Ir(C^N)_3 (C^N = 2-phenylpyridyl (ppy), 2-(4,6-difluorophenyl)pyridyl (F2ppy), 1-phenylpyrazolyl (ppz), 1-(2,4-difluorophenyl)pyrazolyl) (F2ppz), and 1-(2-(9,9′-dimethylfluorenyl))pyrazolyl (flz)), fac-Ir(C^N)_2(C^N′) (C^N = ppz or F2ppz and C^N′ = ppy or F2ppy), and fac-Ir(CC′)_3 (C^C′ = 1-phenyl-3-methylbenzimidazolyl (pmb)) have been studied in dilute 2-methyltetrahydrofuran (2-MeTHF) solution in a temperature range of 77−378 K. Photoluminescent quantum yields (Φ) for the 10 compounds at room temperature vary between near zero and unity, whereas all emit with high efficiency at low temperature (77 K). The quantum yield for fac-Ir(ppy)_3 (Φ = 0.97) is temperature-independent. For the other complexes, the temperature-dependent data indicates that the luminescent efficiency is primarily determined by thermal deactivation to a nonradiative state. Activation energies and rate constants for both radiative and nonradiative processes were obtained using a Boltzmann analysis of the temperature-dependent luminescent decay data. Activation energies to the nonradiative state are found to range between 1600 and 4800 cm^−1. The pre-exponential factors for deactivation are large for complexes with C^N ligands (1011−1013 s^−1) and significantly smaller for fac-Ir(pmb)_3 (109 s^−1). The kinetic parameters for decay and results from density functional theory (DFT) calculations of the triplet state are consistent with a nonradiative process involving Ir−N (Ir−C for fac-Ir(pmb)_3) bond rupture leading to a five-coordinate species that has triplet metal-centered (^3MC) character. Linear correlations are observed between the activation energy and the energy difference calculated for the emissive and ^3MC states. The energy level for the ^3MC state is estimated to lie between 21700 and 24000 cm^−1 for the fac-Ir(C^N)_3 complexes and at 28000 cm^−1 for fac-Ir(pmb)_3

Restructuring Gauteng City Region in South Africa: Is a Transportation Solution the Answer?

The Gauteng city region forms the economic hub of socio-economic development and growth in South Africa. The province itself includes the Johannesburg metropolitan city, Ekurhuleni metropolitan city as well as Tshwane municipality—key urban growth regions of Gauteng province, South Africa, and by extension Southern Africa. The region exhibits the rapid urbanisation challenges typical in any developing country city. Rural–urban migration, pressure on infrastructure demand, supply and capacity constraints and mismatches in urban governance structures with respect to service delivery have remained stubborn challenges. Initiatives and strategies to resolve urban traffic congestion such as through road construction and highway expansion (physical instrument), e-tolling of roads (financial instrument), innovative housing and waste management technology deployment (technology instruments) as well as presenting advanced spatial planning and development and management systems (planning and regulatory instruments) have been employed with mixed fortunes in attempts to (re)solve the urban problems in the study area. Making use of a thematic approach and technique, the major urbanisation issues are explored and solutions proffered. Recommendations revolve around the need to implement robust and progressive rafts of projects, programmes, activities, measures and actions to reverse spatial fragmentation and spatially inefficient transport induced and perpetuated disadvantages

CGM2, a Member of the Carcinoembryonic Antigen Gene Family is Down- Regulated in Colorectal Carcinomas

We have determined the precise chromosomal location, the exon structure, and the expression pattern of CGM2, a member of the carcinoembryonic antigen (CEA) gene family. CGM2 cDNA was amplified by reverse transcription-polymerase chain reaction (RT/PCR) from the colon adenocarcinoma cell line, LS174T. A defective exon is missing from this cDNA clone, leading to a novel domain organization for the human CEA family with two immunoglobulin-like domains. The derived C-terminal domain predicts that the CGM2 protein is membrane-bound through a glycosyl phosphatidylinositol anchor. RT/PCR analyses identified CGM2 transcripts in mucinous ovarian and colonic adenocarcinomas as well as in adjacent colonic tissue, but not in other tumors including leukocytes from six chronic myeloid leukemia patients. Thus, unlike several other family members, CGM2 is not expressed in granulocytes but reveals a more CEA-like expression pattern. Northern blot analyses identified a 2.5-kilobase CGM2 mRNA that is strongly down-regulated in colonic adenocarcinomas compared with adjacent colonic mucosa, suggesting a possible tumor suppressor function. In addition, a 3.2- kilobase transcript was observed in a number of colon tumors that is not detectable in normal colonic tissue. This mRNA species could represent a tumor-specific CGM2 splice variant

An Inviscid Decoupled Method for the Roe FDS Scheme in the Reacting Gas Path of FUN3D

An approach is described to decouple the species continuity equations from the mixture continuity, momentum, and total energy equations for the Roe flux difference splitting scheme. This decoupling simplifies the implicit system, so that the flow solver can be made significantly more efficient, with very little penalty on overall scheme robustness. Most importantly, the computational cost of the point implicit relaxation is shown to scale linearly with the number of species for the decoupled system, whereas the fully coupled approach scales quadratically. Also, the decoupled method significantly reduces the cost in wall time and memory in comparison to the fully coupled approach. This work lays the foundation for development of an efficient adjoint solution procedure for high speed reacting flow

Performance of Spatial Modulation using Measured Real-World Channels

In this paper, for the first time real-world channel measurements are used to analyse the performance of spatial modulation (SM), where a full analysis of the average bit error rate performance (ABER) of SM using measured urban correlated and uncorrelated Rayleigh fading channels is provided. The channel measurements are taken from an outdoor urban multiple input multiple output (MIMO) measurement campaign. Moreover, ABER performance results using simulated Rayleigh fading channels are provided and compared with a derived analytical bound for the ABER of SM, and the ABER results for SM using the measured urban channels. The ABER results using the measured urban channels validate the derived analytical bound and the ABER results using the simulated channels. Finally, the ABER of SM is compared with the performance of spatial multiplexing (SMX) using the measured urban channels for small and large scale MIMO. It is shown that SM offers nearly the same or a slightly better performance than SMX for small scale MIMO. However, SM offers large reduction in ABER for large scale MIMO.Comment: IEEE Vehicular Technology Conference Fall 2013 (VTC-Fall 2013), Accepte