Mobility through Heterogeneous Networks in a 4G Environment

Serving and Managing users in a heterogeneous environment. 17th WWRF Meeting in Heidelberg, Germany, 15 - 17 November 2006. [Proceeding presented at WG3 - Co-operative and Ad-hoc Networks]The increase will of ubiquitous access of the users to the requested services points towards the integration of heterogeneous networks. In this sense, a user shall be able to access its services through different access technologies, such as WLAN, Wimax, UMTS and DVB technologies, from the same or different network operators, and to seamless move between different networks with active communications. In this paper we propose a mobility architecture able to support this users’ ubiquitous access and seamless movement, while simultaneously bringing a large flexibility to access network operators

The X-ray Ridge Surrounding Sgr A* at the Galactic Center

We present the first detailed simulation of the interaction between the supernova explosion that produced Sgr A East and the wind-swept inner ~ 2-pc region at the Galactic center. The passage of the supernova ejecta through this medium produces an X-ray ridge ~ 9'' to 15'' to the NE of the supermassive black hole Sagittarius A* (Sgr A*). We show that the morphology and X-ray intensity of this feature match very well with recently obtained Chandra images, and we infer a supernova remnant age of less than 2,000 years. This young age--a factor 3--4 lower than previous estimates--arises from our inclusion of stellar wind effects in the initial (pre-explosion) conditions in the medium. The supernova does not clear out the central ~ 0.2-pc region around Sgr~A* and does not significantly alter the accretion rate onto the central black hole upon passage through the Galactic center.Comment: 10 pages, 3 figures, submitted to ApJ

Safety climates in construction industry: understanding the role of construction sites and workgroups

Studies of safety climate in construction revealed a significant positive association between safety climate and various aspects of occupational health and safety. The mechanisms through which this impact operates are still unclear and safety climate is usually studied without considering the complexity of this industry (companies, worksites and groups). The aim of this research is to analyze to what extend there are differences between construction sites and to explore the relations between construction sites’ safety climate and workers’ safety response and to examine how this influence occur considering the workgroups. The safety climate was evaluated using a reduced version of the questionnaire that is a part of Battery HERC (Herramienta para evaluacion riesgos comportamentales). The data were collected in a Portuguese construction company (5 construction sites; including sub-contractors) comprising 213 workers. Differences between construction sites safety climate were found, suggesting the prevalence of safety sub-climates. The workgroup safety climate played a determinant role on workers’ safety response in subcontracted workgroups and it is an important mechanism through which the principal contractor can influence subcontractors’ safety response. Designers of preven- tion and training programs for accidents prevention should include specific contents in order to improve supervisory safety leadership and workgroup safety responses

Feasibility of targeted early detection for melanoma: a population-based screening study

The feasibility of targeted screening for cutaneous malignant melanoma in the UK using a postal questionnaire and invitation to screening by a consultant dermatologist was investigated in a population based cross-sectional survey. A total of 1600 people aged 25–69 years, stratified by the social deprivation score of wards within one general practice, were randomly selected from a population of 8000.1227 (77%) returned the questionnaire and 896 (56%) attended the screening clinic. Uptake was lower for men (P< 0.001), those aged under 50 (P< 0.001), people from deprived areas (P< 0.001) and skin types III and IV (men only, P< 0.001). Twenty per cent of women and 10% of men felt nervous about attending the clinic, but only 4% were worried by the questionnaire. The level of agreement between the self- and dermatologist's assessments of risk factors was best for hair colour (Kappa = 0.67, sensitivity 73% and specificity 98%). People tended to under-report their level of risk. Over 95% knew about at least one major sign, but 54% reported incorrect signs of melanoma. Targeted screening for melanoma in the UK will be hampered by difficulties in accurately identifying the target population. Strategies to improve skin self-awareness rather than screening should be developed and evaluated. © 2000 Cancer Research Campaig

Spin-Induced Disk Precession in Sagittarius A*

In Sgr A* at the Galactic center, by far the closest and easiest supermassive black hole we can study, the observational evidence is increasingly pointing to the presence of a compact, hot, magnetized disk feeding the accretor. In such low-Mach-number plasmas, forces arising, e.g., from pressure gradients in the plasma, can altogether negate the warping of disks around Kerr black holes caused by the Bardeen-Petterson effect and can lead to coherent precession of the entire disk. In this Letter, we present for the first time highly detailed 3D SPH simulations of the accretion disk evolution in Sgr A*, guided by observational constraints on its physical characteristics, and conclude that indeed the Bardeen-Petterson effect is probably absent in this source. Given what we now understand regarding the emission geometry in this object, we suggest that a ~ 50-500-day modulation in Sgr A*'s spectrum, arising from the disk precession, could be an important observational signature; perhaps the ~ 106-day period seen earlier in its radio flux, if confirmed, could be due to this process. On the other hand, if future observations do not confirm this long modulation in Sgr A*'s spectrum, this would be an indication that either the disk size or orientation is very different from current estimates, or that the black hole is not spinning at all (unlikely), or that our current understanding of how it produces its radiative output is incorrect.Comment: 14 pages, 3 figures; small changes to sections 2.1 and 3; accepted for publication in Ap

A Monte Carlo Study of the 6.4 keV Emission at the Galactic Center

Strong fluorescent Fe line emission at 6.4 keV has been observed from the Sgr B2 giant molecular cloud located in the Galactic Center region. The large equivalent width of this line and the lack of an apparent illuminating nearby object indicate that a time-dependent source, currently in a low-activity state, is causing the fluorescent emission. It has been suggested that this illuminator is the massive black hole candidate, Sgr A*, whose X-ray luminosity has declined by an unprecedented six orders of magnitude over the past 300 years. We here report the results of our Monte Carlo simulations for producing this line under a variety of source configurations and characteristics. These indicate that the source may in fact be embedded within Sgr B2, although external sources give a slightly better fit to the data. The weakened distinction between the internal and external illuminators is due in part to the instrument response function, which accounts for an enhanced equivalent width of the line by folding some of the continuum radiation in with the intrinsic line intensity. We also point out that although the spectrum may be largely produced by K$\alpha$ emission in cold gas, there is some evidence in the data to suggest the presence of warm (~10^5 K) emitting material near the cold cloud.Comment: 11 pages, 4 figure

Survey of the rate of PSA testing in general practice

The use of prostate specific antigen (PSA) test could have a large impact on the incidence of prostate cancer in the UK. Over a period of 1 year (1999), 3.5% out of 160 015 men aged > 45 on a GP database, who had no previous record of prostate cancer, had a PSA test. Of the tested men, 21.3% had a PSA > 4 ng/ml. Future data need to distinguish between men with and without symptoms. © 2001 Cancer Research Campaign http://www.bjcancer.co

Cosmological Implications of the CMB Large-scale Structure

WMAP and Planck may have uncovered several anomalies in the full CMB sky that could indicate possible new physics driving the growth of density fluctuations in the early Universe. These include an unusually low power at the largest scales and an apparent alignment of the quadrupole and octopole moments. In LCDM, the quadrupole and octopole moments should be statistically independent. These low probability features may simply be due to posterior selections from many such possible effects. If this is not the case, however, their combined statistical significance would be equal to the product of their individual significances. Ignoring the biasing due to posterior selection, the missing large-angle correlations would have a probability as low as ~0.1% and the low-l multipole alignment would be unlikely at the ~4.9% level; under the least favourable conditions, their simultaneous observation in the context of the standard model could then be likely at only the ~0.005% level. In this paper, we explore the possibility that these features are indeed anomalous, and show that the corresponding probability of CMB multipole alignment in the R_h=ct Universe would then be ~7-10%, depending on the number of large-scale Sachs-Wolfe induced fluctuations. Since the low power at the largest spatial scales is reproduced in this cosmology without the need to invoke cosmic variance, the overall likelihood of observing both of these features in the CMB is > 7%, much more likely than in LCDM. The key physical ingredient responsible for this difference is the existence in the former of a maximum fluctuation size at the time of recombination, which is absent in the latter because of inflation.Comment: 34 pages, 6 figures. Accepted for publication in the Astronomical Journal. arXiv admin note: text overlap with arXiv:1207.001

A Persistent High-Energy Flux from the Heart of the Milky Way : Integral's view of the Galactic Center

The Ibis/Isgri imager on Integral detected for the first time a hard X-ray source, IGR J17456-2901, located within 1' of Sgr A* over the energy range 20-100 keV. Here we present the results of a detailed analysis of ~7 Ms of Integral observations of the GC. With an effective exposure of 4.7 Ms we have obtained more stringent positional constraints on this HE source and constructed its spectrum in the range 20-400 keV. Furthermore, by combining the Isgri spectrum with the total X-ray spectrum corresponding to the same physical region around SgrA* from XMM data, and collected during part of the Integral observations, we constructed and present the first accurate wide band HE spectrum for the central arcmins of the Galaxy. Our complete analysis of the emission properties of IGR shows that it is faint but persistent with no variability above 3 sigma contrary to what was alluded to in our first paper. This result, in conjunction with the spectral characteristics of the X-ray emission from this region, suggests that the source is most likely not point-like but, rather, that it is a compact, yet diffuse, non-thermal emission region. The centroid of IGR is estimated to be R.A.=17h45m42.5, decl.=-28deg59'28'', offset by 1' from the radio position of Sgr A* and with a positional uncertainty of 1'. Its 20-400 keV luminosity at 8 kpc is L=5.4x10^35 erg/sec. Very recently, Hess detected of a source of ~TeV g-rays also located within 1' of Sgr A*. We present arguments in favor of an interpretation according to which the photons detected by Integral and Hess arise from the same compact region of diffuse emission near the central BH and that the supernova remnant Sgr A East could play an important role as a contributor of very HE g-rays to the overall spectrum from this region.Comment: 14 pages, 11 figures, Accepted for publication in Ap

Carfree and low-car development

© 2014 by Emerald Group Publishing Limited All rights of reproduction in any form reserved. Purpose-This chapter defines and describes the different types of carfree and low-car development found in the United Kingdom and continental Europe, analysing the benefits and problems they bring and their implications for parking policy. Methodology/approach-The chapter draws on the literature on UK and European carfree developments, including primary research conducted by the author into the potential for carfree development in the United Kingdom. It is also informed by a series of observational visits to some of the principal carfree developments around Europe. Findings-The UK concepts of car-free and low-car housing are limited in scope, defined by the absence or reduced level of parking. The European concept of carfree development is broader, bringing greater benefits to the immediate residents. All have led to lower traffic generation. European carfree developments bring other benefits to their residents such as more socialisation between neighbours and earlier independence for children. The potential demand for car-free and low-car housing is greatest in the inner areas of larger cities. These are also the places which offer the most suitable development locations. The most common problems encountered relate to parking and/or management of vehicular access. To avoid overspill problems, parking needs to be controlled on the streets surrounding carfree or low-car developments. Practical implications-The benefits of carfree development are greatest in urban areas where road capacity and/or parking are under the greatest pressure. Thus carfree development is a useful tool for cities undergoing urban intensification. Originality/value of paper-The chapter is the first to analyse carfree and low-car development from a parking perspective and to demonstrate their implications for parking policy