A comparison of global models for the solar wind interaction with Mars

We present initial results from the first community-wide effort to compare global plasma interaction model results for Mars. Seven modeling groups participated in this activity, using MHD, multi-fluid, and hybrid assumptions in their simulations. Moderate solar wind and solar EUV conditions were chosen, and the conditions were implemented in the models and run to steady state. Model output was compared in three ways to determine how pressure was partitioned and conserved in each model, the location and asymmetry of plasma boundaries and pathways for planetary ion escape, and the total escape flux of planetary oxygen ions. The two participating MHD models provided similar results, while the five sets of multi-fluid and hybrid results were different in many ways. All hybrid results, however, showed two main channels for oxygen ion escape (a pickup ion ‘plume’ in the hemisphere toward which the solar wind convection electric field is directed, and a channel in the opposite hemisphere of the central magnetotail), while the MHD models showed one (a roughly symmetric channel in the central magnetotail). Most models showed a transition from an upstream region dominated by plasma dynamic pressure to a magnetosheath region dominated by thermal pressure to a low altitude region dominated by magnetic pressure. However, calculated escape rates for a single ion species varied by roughly an order of magnitude for similar input conditions, suggesting that the uncertainties in both the current and integrated escape over martian history as determined by models are large. These uncertainties are in addition to those associated with the evolution of the Sun, the martian dynamo, and the early atmosphere, highlighting the challenges we face in constructing Mars’ past using models.     

Geochemical and H-O-Sr-Nd isotope evidence for magmatic processes and meteoric-water interactions in the basal complex of La Gomera, Canary Islands

The plutonic rocks of the Basal Complex of La Gomera, Canary Islands, Spain, were studied by means of major and trace element contents and by H-O-Sr-Nd isotope compositions in order to distinguish primary magmatic characteristics and late-stage alteration products. Deciphering the effects of alteration allowed us to determine primary, plume-related compositions that indicated D- and ¹⁸O-depletion relative to normal upper mantle, supporting the conclusions of earlier studies on the plutonic rocks of Fuerteventura and La Palma. Late-stage alteration took place during the formation of the intrusive series induced by interaction with meteoric water. Inferred isotopic compositions of the meteoric water indicate that the water infiltrated into the rock edifice at a height of about 1500 m above sea level, suggesting the existence of a subaerial volcano which was active during the intrusive activity and that it has been either distroyed or remain buried by later volcanic and landslide events.     

Regional disparities in Hungary during the period of transition to a market economy

Disparities in Hungary can be characterized regionally with the dualism of Budapest and the countryside, with the western and eastern division of the country itself, with local crises of the broken down industrial axis and marginal geographic settings, with the differentation according to the hierarchy and size of settlements. Two thirds of the total foreign capital invested in Hungary and half of the joint ventures are concentrated in the capital. Apart from Budapest, it causes a higher unemployment rate and lower taxable incomes.     

Planning regional development: Promoting small settlements in a trans-frontier situation

Under communism local authorities tended to be largely passive bystanders in a regional development process which emerged through the central planning process through the spatial allocations of investment by government ministries. Attention was given to physical planning, but comparatively little material entered the public domain on location policy and spatial priorities generally, apart from the objective of greater equality between regions and a commitment to backward areas generally. Now that much investment is down to private enterprise and government has become more decentralised and accountable, there is a need for concepts and strategies to coordinate public sector investment and provide guidelines for the evaluation of private development proposals. At the same time, there is an open competition for investment which requires communities to promote themselves in terms of their identity and development potential. This paper offers an overview by taking two countries - Hungary and Romania - where progress can be compared and where the focus can be placed on a common frontier which is diverting attention from conventional regional planning to cross-border cooperation. In both contexts however, attention is given to the ways in which planning can divert investment away from the main centres to the peripheral areas, including action to strengthen the role of small towns and also to improve cohesion among functionally-related groups of settlements and communes. This revised version was published online in July 2006 with corrections to the Cover Date.     

A stability study of Kuiper Belt binaries

The dynamical structure of the orbital element space of seven Kuiper Belt binary systems is studied by numerical methods in the model of the spatial elliptic restricted three‐body problem. It is shown that three systems have an extended region of stability where additional satellites could exist. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The gravitational potential and its derivatives for the prism

 As a simple building block, the right rectangular parallelepiped (prism) has an important role mostly in local gravity field modelling studies when the so called flat-Earth approximation is sufficient. Its primary (methodological) advantage follows from the simplicity of the rigorous and consistent analytical forms describing the different gravitation-related quantities. The analytical forms provide numerical values for these quantities which satisfy the functional connections existing between these quantities at the level of numerical precision applied. Closed expressions for the gravitational potential of the prism and its derivatives (up to the third order) are listed for easy reference. Received: 18 August 1999 / Accepted: 15 June 2000     

Effects of urbanization on stream hydrology and water quality: the Florida Gulf Coast

At the global scale, the population density of coastal areas is nearly three times that of inland areas, and consequently, land development represents a threat to coastal ecosystems. It is critical to understand how increasing urbanization affects coastal watersheds. To that end, the objective of this study was to examine the influence of urban development on stream water quality and hydrology in a coastal setting, a scenario that has received less attention than other physiographic regions. Stream hydrologic, physicochemical, and microbial data were collected in watersheds near Apalachicola, Florida with a range of impervious surfaces from 0 to 15%. Watersheds with greater impervious cover exhibited higher pH, specific conductance, and temperature, elevated nutrient concentrations and loads (, and total phosphorus), higher bacterial concentrations (fecal coliform and Escherichia coli), and increased maximum flow and hydrograph flashiness. Different responses to development here compared to other physiographic regions included lower total suspended solid concentrations, higher total dissolved solid concentrations, and a lack of response of base flow to increased urbanization. Additionally, Na⁺ and Cl^? concentrations were elevated to a greater extent than is often the case in non‐coastal areas. In the coming years, urban development is projected to increase substantially in coastal zones and thus there is risk of further stream degradation in coastal watersheds. Copyright © 2011 John Wiley & Sons, Ltd.     

Organic solids produced by electrical discharge in reducing atmospheres: Tholin molecular analysis

The complex dark brown solid of a class called tholins, produced on passage of an electrical discharge through a roughly equimolar mixture of methane and ammonia with 2.6% water vapor, is analyzed by vacuum pyrolysis followed by gas chromatography and mass spectrometry. Pyrolyzates include a wide range of aliphatic and aromatic nitriles, alkanes, aromatic hydrocarbons, pyrrole, and pyridine. This tholin is remarkably stable to 950°C. It and its degradation products are candidate constituents of planetary aerosols in the outer solar system and of the grains in the interstellar medium.