A design study of an energy-dissipating cladding system

A design study has been conducted to explore the use of structural cladding panels with energy-dissipating cladding-to-frame connections for seismic-resistant design. The study identifies several issues involved in the modelling and analysis of frames with energy-dissipating cladding-to-frame connections, establishes concepts for design, and provides a preliminary assessment of the force and deformation demands that are likely to be placed on panels and connections. Non-linear dynamic analyses indicate that the clad frames perform well, based on observations about maximum interstorey drifts, maximum plastic hinge rotations in the frames, and maximum ductility demands on the cladding-to-frame connections.     

Planetary elements for 10 000 000 years

In 1950 Brouwer and van Woerkom published a secular theory of the variations of the planetary elements in analytical form. In the present paper we provide a graphical representation of this theory in the form of element plots for a time span of ten million years.     

Long-Term Evolution of Objects in the Kuiper Belt Zone—Effects of Insolation and Radiogenic Heating

The Kuiper Belt zone is unique insofar as the major heat sources of objects a few tens of kilometers in size—solar radiation on the one hand and radioactive decay on the other—have comparable power. This leads to unique evolutionary patterns, with heat waves propagating inward from the irradiated surface and outward from the radioactively heated interior. A major radioactive source that is considered in this study is ²⁶Al. The long-term evolution of several models with characteristics typical of Kuiper Belt objects is followed by means of a 1-D numerical code that solves the heat and mass balance equations on a spherically symmetric grid. The free parameters considered are radius (10-500 km), heliocentric distance (30-120 AU), and initial ²⁶Al content (0-5×10⁻⁸ by mass). The initial composition assumed is a porous mixture of ices (H₂O, CO, and CO₂) and dust. Gases released in the interior are allowed to escape to the surface. It is shown that, depending on parameters, the interior may reach quite high temperatures (up to 180 K). The models suggest that Kuiper Belt objects are likely to lose the ices of very volatile species during early evolution; ices of less volatile species are retained in a surface layer, about 1 km thick. The models indicate that the amorphous ice crystallizes in the interior, and hence some objects may also lose part of the volatiles trapped in amorphous ice. Generally, the outer layers are far less affected than the inner part, resulting in a stratified composition and altered porosity distribution. These changes in structure and composition should have significant consequences for the short-period comets, which are believed to be descendants of Kuiper Belt objects.     

The use of transplanted cultured tropical oysters (Saccostrea commercialis) to monitor Cd levels in North Queensland coastal waters (Australia)

Bivalves are commonly used to detect metal pollution in the marine environment. Commercially cultured Milky oysters (Saccostrea commercialis) were transplanted in various sites along the North Queensland coast and analyzed for two metals of potentially anthropogenic origin (Cd, Zn). To provide additional information, naturally occurring Black Lip oysters (Saccostrea echinata) were also collected at the transplantation sites. The study demonstrated that the oysters species transplanted are good bioindicators of these metal concentrations in tropical waters, sensitive to variations in the environment at concentrations which are much smaller than pollution signals commonly reported for temperate waters. Three transplant experiments were carried out from May 1999 to February 2000. Milky oysters transplanted to offshore areas (Orpheus Is., Kelso Reef) accumulated Cd in the soft parts whereas oysters sampled from cages placed in Ross Creek and the Herbert River estuaries showed a decrease in Cd concentration, which resulted from an increase in dry weight. Dry weight appeared to be an important covariant affecting Cd concentration in the oysters whereas it does not unambiguously affect Zn concentrations. For the duration of the experiments, oysters sampled from the Magnetic Is. reference site showed effectively constant Cd concentrations and total Cd contents which indicates that any seasonal cycle affecting metal concentration is weak. It was found that Cd accumulation in oysters increased as ambient dissolved Cd concentration decreased, from which it was concluded that for these oysters, the predominant source of Cd was from the particulate phase rather than the dissolved phase.     

From overt rejection to enthusiastic embracement: changing state discourses on Israeli emigration

This paper deploys a critical discourse analysis methodology to examine the emergence of three (sometimes overlapping) discourses on emigration in Israel. It examines the linkages between the various discursive phases and processes of (trans-) national identity formation among emigrants. It argues that emigration discourses have often been strong predictors of subsequent changes in state policies—and other programmatic initiatives—aimed at Israeli citizens abroad. By juxtaposing the discursive construction of emigration (and its linkages to nation-forming political strategies in Israel) and the effects they have had on emigrant identities the paper contributes to the emerging literature on state-diaspora relations and transnational politics.     

Mid-Holocene to present-day evolution of the Indian monsoon in transient global simulations

The low-frequency evolution of Indian rainfall mean-state and associated interannual-to-decadal variability is discussed for the last 6000 years from a multi-configuration ensemble of fully coupled global transient simulations. This period is marked by a shift of Indian Summer Monsoon Rainfall (ISMR) distribution towards drier conditions, including extremes, and a contraction of the rainy season. The drying is larger in simulations with higher horizontal resolution of the atmosphere and revised land surface hydrology. Vegetation–climate interactions and the way runoff is routed to ocean modulate the timing of the monsoon onset but have negligible effects on the evolution of seasonal rainfall amounts in our modeling framework in which carbon cycling is always active. This drying trend is accompanied by changes in ISMR interannual-to-decadal variability decreasing over north and south India but increasing over central India (20°–25° N). The ISMR interannual-to-decadal variability is decomposed into six physically consistent regimes using a clustering technique to further characterize its changes and associated teleconnections. From 6 to 3.8 kyr bp, the century-to-century modulations in the frequency of occurrence associated to the regimes are asynchronous between the simulations. Orbitally-driven trends can only be detected for two regimes over the whole 6–0 kyr bp period. These two regimes reflect increased influence of ENSO on both ISMR and Indian Ocean Dipole as the inter-hemispheric energy gradient weakens. Severe long-term droughts are also shown to be a combination of long-term drying and internally generated low-frequency modulations of the interannual-to-decadal variability.

     

The complex gravitational lens system B1933+503

We report the discovery of the most complex arcsec-scale radio gravitational lens system yet known. B1933+503 was found during the course of the CLASS survey and MERLIN and VLA radio maps reveal up to 10 components. Four of these are compact and have flat spectra; the rest are more extended and have steep spectra. The background lensed object appears to consist of a flat-spectrum core (quadruply imaged) and two compact 'lobes' symmetrically disposed relative to the core. One of the lobes is quadruply imaged while the other is doubly imaged. An HST observation of the system with the WFPC2 shows a galaxy with an axial ratio of 0.5, but none of the images of the background object is detected. A redshift of 0.755 has been measured for the lens galaxy.     

A study of transient variations in the Earth’s electromagnetic field at equatorial electrojet latitudes in western Africa (Mali and the Ivory Coast)

In the framework of the French-Ivorian participation to the IEEY, a network of 10 electromagnetic stations were installed at African longitudes. The aim of this experiment was twofold: firstly, to study the magnetic signature of the equatorial electrojet on the one hand, and secondly, to characterize the induced electric field variations on the other hand. The first results of the magnetic field investigations were presented by Doumouya and coworkers. Those of the electric field experiment will be discussed in this study. The electromagnetic experiment will be described. The analysis of the electromagnetic transient variations was conducted in accordance with the classical distinction between quiet and disturbed magnetic situations. A morphological analysis of the recordings is given, taking into consideration successively quiet and disturbed magnetic situations, with the results interpreted in terms of the characterization of external and internal sources. Particular attention was paid to the effects of the source characteristics on the induced field of internal origin, and to the bias they may consequently cause to the results of electromagnetic probing of the Earth; the source effect in electromagnetic induction studies. During quiet magnetic situations, our results demonstrated the existence of two different sources. One of these, the S_R^E source, was responsible for most of the magnetic diurnal variation and corresponded to the well-known magnetic signature of the equatorial electrojet. The other source (the S_R*^E source) was responsible for most of the electric diurnal variation, and was also likely to be an ionospheric source. Electric and magnetic diurnal variations are therefore related to different ionospheric sources, and interpreting the electric diurnal variation as induced by the magnetic field diurnal variation is not relevant. Furthermore, the magnetotelluric probing of the upper mantle at dip equator latitudes with the electromagnetic diurnal variation is consequently impossible to perform. In the case of irregular variations, the source effect related to the equatorial electrojet is also discussed. A Gaussian model of equatorial electrojet was considered, and apparent resistivities were computed for two models of stratified Earth corresponding to the average resistive structure of the two tectonic provinces crossed by the profile: a sedimentary basin and a cratonic shield. The apparent resistivity curves were found to depend significantly on both the model used and the distance to the center of the electrojet. These numerical results confirm the existence of a daytime source effect related to the equatorial electrojet. Furthermore, we show that the results account for the observed differences between daytime and night-time apparent resistivity curves. In particular, it was shown that electromagnetic probing of the Earth using the classical Cagniard-Tikhonov magnetotelluric method is impossible with daytime recordings made at dip latitude stations.