A New Approach for Studying Hubble Diagrams of Quasars

In this paper, a new approach for studying Hubble diagrams of quasars is introduced. The purpose is to reduce the well-known very large scatter in the diagram. We believe that the scatter is mainly caused by the wide spread of luminosity distribution of quasars. Based on a large number of quasars having been discovered, we introduce a new quantity, the collective apparent magnitude of certain amount of quasars in a corresponding redshift interval, and make a plot of the collective apparent magnitude versus redshift with the data published by Hewitt and Burbidge (1993). The quantity is contributed by individual apparent luminosities as well as the luminosity distribution of quasars. Scatter is expected to be largely reduced in the corresponding diagram, and this is indeed true as shown by the figures. By discussing several possible effects and from the figures, we find that the assumption that redshifts of quasars are distance indicators is confirmed, and the standard cosmological model is supported. This revised version was published online in July 2006 with corrections to the Cover Date.     

Mining geohazards—land subsidence caused by the dewatering of opencast coal mines: The case study of the Amyntaio coal mine, Florina, Greece

Mining activities impact the nearby environment, causing the so-called mining hazards. The land subsidence phenomena caused by the dewatering of the mines are listed among the mining-induced catastrophic geohazards slowly affecting extensive areas around the opencasts. These large-scale geo-hazards are related to both hydrogeological and geotechnical factors, and they cause irreversible damages. The research presented aims to clarify all the components of the phenomenon and to establish the proper modelling procedure for the study of its mechanism. The site under investigation is the area extending at the west—northwest of the Amyntaio opencast coal mine at Florina Prefecture, Northern Greece. The overexploitation of the aquifers for the protection of the slopes turned the opencast to a large-diameter well, draining the surrounding area. The extensive land subsidence phenomena extend 3–4 km around the mine causing severe damages in two villages. The established results can be used for monitoring and predicting the impact of the particular mining hazard on the natural and human environment, without precluding further exploitation and mining of the energy resources.     

Dynamic testing and system identification of a multi-span highway bridge

A simple and effective procedure for conducting the free vibration test on highway bridges is presented. The impulsive force in each direction is generated by a loaded truck that either stops suddenly or falls down from a rigid block. The feasibility of the procedure is demonstrated in identification of the dynamic properties, i.e. the vibration frequencies, mode shapes, and damping ratios, of a three-span box-girder concrete bridge using the Ibrahim Time-Domain (ITD) technique. Up to 14 modes have been identified for the present case. For the purpose of verification, ambient vibration tests were also carried out, with the data processed by the random decrement (Randomdec) technique to yield the free vibration response, followed by the ITD technique. The dynamic properties identified from the two types of test correlate very well with each other, indicating the validity of each procedure described herein. Although many more modes can be identified from the free vibration test because of the higher quality of data produced, the easiness and general applicability of the ambient vibration test can still be appreciated. A comparison of the experimental results with those by the finite element method indicated a lesser degree of correlation, implying that the finite element model adopted in design requires further refinement, say, through a more realistic evaluation of the boundary conditions, geometric and material properties of the bridge. Copyright © 1999 John Wiley & Sons Ltd.     

The unusual X-ray light curve of GRB 080307: the onset of the afterglow?

Swift -detected GRB 080307 showed an unusual smooth rise in its X-ray light curve around 100 s after the burst, at the start of which the emission briefly softened. This 'hump' has a longer duration than is normal for a flare at early times and does not demonstrate a typical flare profile. Using a two-component power-law-to-exponential model, the rising emission can be modelled as the onset of the afterglow, something which is very rarely seen in Swift -X-ray light curves. We cannot, however, rule out that the hump is a particularly slow early-time flare, or that it is caused by upscattered reverse shock electrons.     

Coordinated Study on Solar Wind Turbulence During the Venus-Express, ACE and Ulysses Alignment of August 2007

At the end of August 2007, Venus, Earth and Ulysses were aligned within a few degrees. This unusual event gives the opportunity to attempt a coordinated study on the radial evolution of solar wind turbulence and coronal transients like CMEs between 0.7 and 1.4 AU. Interplanetary magnetic field data and moments of proton velocity distribution function such as density, speed and temperature are required for this programme and will be provided by ACE at Earth, Venus Express at Venus and Ulysses at 1.4 AU. This project has been recently proposed as a Coordinated Investigation Programme (CIP35) for the International Heliophysical Year.     

Seabirds and chronic oil pollution: self-cleaning properties of gulls, Laridae, as revealed from colour-ring sightings

Mystery oil spills off the Dutch coast affected colonial, adult Lesser Black-backed Gulls prior to and within the breeding season. From colour-ringed individuals, it was demonstrated that most oiled birds survived and were clean within a few weeks and often bred successfully. Further evidence of self-cleaning properties of Larus-gulls is provided from a long-term colour-ringing project (1984-2009). In total 46 birds were reported ‘oiled’, two died, but the majority cleaned itself and survived for up to 20 years after being oiled. From colour-ring data and 30 years of beached bird surveys (1980-2010) it is demonstrated that the effects of chronic oil pollution is larger in winter than in summer; a reflection of seasonal differences in exposure and environmental conditions. The self-cleaning properties of gulls are such that long-term survival is not necessarily jeopardised and even in a breeding season, not all is lost in case of a spill.     

Effects of onshore and offshore topography on sea breeze circulation: An observational study at eastern Attica,Greece

Field measurements of wind, air temperature and humidity were taken at the eastern part of the Attika district in June 1991, to examine the topographic influences exerted on the local sea breezes. These influences are due either to the elongated Evia island, faced by the northern half of Attica coastline some tens of kilometers offshore, or to the coast-parallel range of Hymettos mountain, rising steeply 12 km onshore. The instrumentation consisted mainly of three tethered meteorological balloons released at characteristic sires (i.e., the coast, a location between shoreline and mountain foot and the mountain top) and three autographic ground-based anemometers operating at selected locations. Data from the ground-based and upper air stations of the Hellenic National Meteorological Service, as well as the diurnal weather maps were also obtained and analyzed. Observations were made under different synoptic wind and the latter was found to determine remarkably the significance of the topographic effects. A preliminary two-dimensional numerical approach was also made concerning the sea breeze capability to reach the Hymettos mountain top in the case of a weak opposing geostrophic flow.     

ESR dating in Song Terus cave (East Java, Indonesia)

Electron spin resonance (ESR) dating on teeth has been used to determine the antiquity of the human presence in the area of Gunung Sewu (East Java, Indonesia). The Song Terus cave is one of the archaeological sites located in this area, which has yielded an important collection of fossil bones and prehistoric lithic industry. ESR dating shows that this cave belongs to a karstic system which has been in place since Middle Pleistocene. The results of coupled ESR/Uranium-series dating indicates closed system for uranium in tooth tissues yielding ages of between 216 and 392 ka for the oldest archaeological levels, confirming the possibility of finding Middle Pleistocene human occupations in such karstic sites in Java.     

An advanced numerical model of elastomeric seismic isolation bearings

The nuclear accident at Fukushima Daiichi in March 2011 has led the nuclear community to consider seismic isolation for new large light water and small modular reactors to withstand the effects of beyond design basis loadings, including extreme earthquakes. The United States Nuclear Regulatory Commission is sponsoring a research project that will quantify the response of low damping rubber (LDR) and lead rubber (LR) bearings under loadings associated with extreme earthquakes. Under design basis loadings, the response of an elastomeric bearing is not expected to deviate from well‐established numerical models, and bearings are not expected to experience net tension. However, under extended or beyond design basis shaking, elastomer shear strains may exceed 300% in regions of high seismic hazard, bearings may experience net tension, the compression and tension stiffness will be affected by isolator lateral displacement, and the properties of the lead core in LR bearings will degrade in the short‐term because of substantial energy dissipation. New mathematical models of LDR and LR bearings are presented for the analysis of base isolated structures under design and beyond design basis shaking, explicitly considering both the effects of lateral displacement and cyclic vertical and horizontal loading. These mathematical models extend the available formulations in shear and compression. Phenomenological models are presented to describe the behavior of elastomeric isolation bearings in tension, including the cavitation and post‐cavitation behavior. The elastic mechanical properties make use of the two‐spring model. Strength degradation of LR bearing under cyclic shear loading due to heating of lead core is incorporated. The bilinear area reduction method is used to include variation of critical buckling load capacity with lateral displacement. The numerical models are coded in OpenSees, and the results of numerical analysis are compared with test data. The effect of different parameters on the response is investigated through a series of analyses. Copyright © 2014 John Wiley & Sons, Ltd.