Dust on the Outskirts of the Jovian System

The outer region of the jovian system between ∼50 and 300 jovian radii from the planet is found to be the host of a previously unknown dust population. We used the data from the dust detector aboard the Galileo spacecraft collected from December 1995 to April 2001 during Galileo's numerous traverses of the outer jovian system. Analyzing the ion amplitudes, calibrated masses and speeds of grains, and impact directions, we found about 100 individual events fully compatible with impacts of grains moving around Jupiter in bound orbits. These grains have moderate eccentricities and a wide range of inclinations—from prograde to retrograde ones. The radial number density profile of the micrometer-sized dust is nearly flat between about 50 and 300 jovian radii. The absolute number density level (∼10 km⁻³ with a factor of 2 or 3 uncertainty) surpasses by an order of magnitude that of the interplanetary background. We identify the sources of the bound grains with outer irregular satellites of Jupiter. Six outer tiny moons are orbiting the planet in prograde and fourteen in retrograde orbits. These moons are subject to continuous bombardment by interplanetary micrometeoroids. Hypervelocity impacts create ejecta, nearly all of which get injected into circumjovian space. Our analytic and numerical study of the ejecta dynamics shows that micrometer-sized particles from both satellite families, although strongly perturbed by solar tidal gravity and radiation pressure, would stay in bound orbits for hundreds of thousands of years as do a fraction of smaller grains, several tenths of a micrometer in radius, ejected from the prograde moons. Different-sized ejecta remain confined to spheroidal clouds embracing the orbits of the parent moons, with appreciable asymmetries created by the radiation pressure and solar gravity perturbations. Spatial location of the impacts, mass distribution, speeds, orbital inclinations, and number density of dust derived from the data are all consistent with the dynamical model.     

Petrologic and geochemical investigation of carbonates in peridotite xenoliths from northeastern Tanzania

Primary carbonates in peridotite xenoliths from the East African Rift in northeastern Tanzania occur as intergranular patches with accessory minerals (olivine and spinel), as patches with accessory magmatic minerals (nepheline), and as round monomineralic inclusions in primary olivine grains. All are characterized by calcitic compositions (Ca/Ca + Mg + Fe from 0.83 to 0.99), extremely low SiO₂ + Al₂O₃ + Na₂O + K₂O, low trace element abundance [total rare-earth element (REE) abundance <25 ppm], uniform extinction, and lack of reaction textures with the host xenolith. Calculated Fe–Mg exchange coefficients between carbonate and primary olivine indicate disequilibrium in most samples. Combined with the lack of significant reaction textures, this suggests that the carbonates were introduced shortly before or during eruption of the host magma. A global compilation of electron microprobe analyses of mantle-derived carbonates (in xenoliths, xenocrysts, and megacrysts) reveals compositional clusters near end member calcite, end member magnesite, and stoichiometric dolomite. Eutectic liquid compositions are less common, suggesting that many carbonate inclusions reported worldwide may be crystalline precipitates. Likewise, the calcites in this study are not interpreted to represent quenched carbonatitic melts, but are interpreted instead to be crystalline cumulates from such melts. These inferences are consistent with recent experiments, which show that carbonatitic melts cannot become more calcitic than CaCO₃∼80 wt%. Low trace element abundance may be a diagnostic feature of cumulate carbonate, and in combination with petrography and major element composition, serve to distinguish it from quenched carbonated liquid. Received: 30 July 1999 / Accepted: 5 February 2000     

MediaPark cologne: A large high tech project to develop Cologne's inner city

All over the world the development in microelectronics and the internationalisation of communications and media production and transmission leads to financial and technological merges: computer and communication and information industries move closer together and give birth to new products, services and organisations. In Cologne, on a large inner city site of 200.000 m² near the Rhine, the Cathedral, Broadcasting Centres and the Central Business District, an innovative development project is under way to promote the further growth and acceptance of new technics and new media production. MediaPark is designed as a centre for activities in microelectronics, arts presentation and production, and centres for professional architectural competition for the design and structure of the planned land use has just started.     

The thermal springs of Jordan

The thermal springs alongside Wadi Araba, Dead Sea and Jordan valley, Jordan, were investigated and sampled in a comprehensive field study of 2 weeks. Conventional physicochemical properties were measured in situ; dissolved solids and isotopic composition were analyzed. Two main spring locations on the east side of the Dead Sea were mapped. It became evident, that the hottest springs are among the closest to prominent faults; some springs are controlled by gas lift. Jordan’s hot springs are described by means of a broad hydrochemical and physicochemical data set and several figures are presented. Based on their hydrochemistry, the thermal springs are classified into four thermal provinces. Water genesis is discussed. Several geothermometers are applied to estimate reservoir temperatures. Observed discharge rate, water temperature and isotopic composition are compared with data from the literature. Although discharge and water temperature are reported to be constant over the last decades, groundwater overexploitation led to a shift of the isotopic composition, what is documented for the first time in Jordan. Thus, the effect of groundwater mining on Jordan’s hot springs can be stated as a fact.     

Impact of the 2010 tsunami on an endangered insular soil–plant system

Natural catastrophes could damage island biodiversity and ecosystems, and their effects could become devastating if combined with human disturbances. In this study, we determined the effects of the tsunami occurred in Robinson Crusoe Island (Chile) on 27 February 2010 on an endangered soil–plant system. Using data of endemic Cabbage Trees (Dendroseris litoralis Skottsb.) and soil attributes taken before and after the 2010 event, we developed thematic maps to assess the changes in population size and soil substrate of Cabbage Trees caused by the tsunami. We determined that from 153 pre-tsunami (2009) standing Cabbage Trees, only 66 (43 %) survived in 2011, mostly in elevations above 25 m a.s.l. Before the tsunami, 86 (56 %) of Cabbage Trees were established in humus-rich soil sites whereas after the tsunami, this number declined to 53 (35 %). These results represent the first report of a severe population decline after a tsunami and indicate that tsunamis are an important source of species extinction in small oceanic islands not only by reducing the population size but also by reducing the quality of sites for plant growth.     

Noble gases in the Xinjiang (Armanty) iron meteorite––A big object with a short cosmic‐ray exposure age

Abstract– We measured the concentrations and isotopic ratios of the cosmogenic noble gases He, Ne, and Ar in the very large iron meteorite Xinjiang (IIIE). The ³He and ⁴He data indicate that a significant portion of the cosmogenic produced helium has been lost via diffusion or in a recent impact event. High ²²Ne/²¹Ne ratios indicate that contributions to the cosmogenic ²¹Ne from sulfur and/or phosphorous are significant. By combining the measured nuclide concentrations with model calculations for iron meteorites we were able to determine the preatmospheric diameter of Xinjiang to 260–320 cm, which corresponds to a total mass of about 70–135 tons. The cosmic‐ray exposure age of Xinjiang is 62 ± 16 Ma, i.e., relatively short compared to most of the other iron meteorites. With the current database we cannot firmly determine whether Xinjiang experienced a complex irradiation history. The finding of ³He and ⁴He losses might argue for a recent impact event and therefore for a complex exposure.     

Silicon in iron meteorite metal

Abstract– We report Si concentrations in the metal phases of iron meteorites. Analyses were performed by secondary ion mass spectrometry using a CAMECA 1270 ion probe. The Si concentrations are low (0.09–0.46 μg g^?1), with no apparent difference in concentration between magmatic and nonmagmatic iron meteorites. Coexisting kamacite and Ni‐rich metal phases have similar Si contents. Thermodynamic calculations show that Fe,Ni‐metal in equilibrium with silicate melts at temperatures where metal crystallizes should contain approximately 100 times more Si than found in iron meteorites in this work. The missing Si may either occur as tiny silicate inclusions in metal or it may have diffused as Si‐metal into surrounding silicates at low temperatures. In both cases, extensive low‐temperature diffusion of Si in metal is required. It is therefore concluded that low Si in iron meteorites is a result of subsolidus reactions during slow cooling.     

On the potential for climate change impacts on marine anthropogenic radioactivity in the Arctic regions

Current predictions as to the impacts of climate change in general and Arctic climate change in particular are such that a wide range of processes relevant to Arctic contaminants are potentially vulnerable. Of these, radioactive contaminants and the processes that govern their transport and fate may be particularly susceptible to the effects of a changing Arctic climate. This paper explores the potential changes in the physical system of the Arctic climate system as they are deducible from present day knowledge and model projections. As a contribution to a better preparedness regarding Arctic marine contamination with radioactivity we present and discuss how a changing marine physical environment may play a role in altering the current understanding pertaining to behavior of contaminant radionuclides in the marine environment of the Arctic region.     

State‐Led Innovation at the City Level: Policy Measures to Promote New Energy Vehicles in Shenzhen,China

Unlike many Western countries, the Chinese state has a much more active role in innovation that includes direct involvement with actors in innovation processes and the use of state capacity, money, and power to attain certain goals. With the rise of China, innovation processes that critically depend on state action, often labeled state‐led innovation, have thus received growing scholarly attention. However, only few contributions study the specific sector of new energy vehicles (NEV) and policy measures applied at the city level. This paper examines policy and planning tools used in Shenzhen, China, to assert innovation in the NEV industry, using an evaluation of documents and interviews. The paper finds that a city can play a decisive role in the implementation of innovation policy, and Chinese cities in particular make use of a broad set of innovation support measures ranging from binding quotas, public procurement, and incentives to bans and orders. The findings underline the importance of strong regulatory instruments that do not conform to the Western notion of market‐compliant policy, but nevertheless work effectively in the Chinese context. Moreover, the results highlight how successful policy support for innovation in the NEV can be implemented.     

What controls equatorial Atlantic winds in boreal spring?

The factors controlling equatorial Atlantic winds in boreal spring are examined using both observations and general circulation model (GCM) simulations from the coupled model intercomparison phase 5. The results show that the prevailing surface easterlies flow against the attendant pressure gradient and must therefore be maintained by other terms in the momentum budget. An important contribution comes from meridional advection of zonal momentum but the dominant contribution is the vertical transport of zonal momentum from the free troposphere to the surface. This implies that surface winds are strongly influenced by conditions in the free troposphere, chiefly pressure gradients and, to a lesser extent, meridional advection. Both factors are linked to the patterns of deep convection. Applying these findings to GCM errors indicates, that, consistent with the results of previous studies, the persistent westerly surface wind bias found in most GCMs is due mostly to precipitation errors, in particular excessive precipitation south of the equator over the ocean and deficient precipitation over equatorial South America. Free tropospheric influences also dominate the interannual variability of surface winds in boreal spring. GCM experiments with prescribed climatological sea-surface temperatures (SSTs) indicate that the free tropospheric influences are mostly associated with internal atmospheric variability. Since the surface wind anomalies in boreal spring are crucial to the development of warm SST events (Atlantic Niños), the results imply that interannual variability in the region may rely far less on coupled air–sea feedbacks than is the case in the tropical Pacific.