A theory for the interpretation of lunar surface magnetometer data

The solution to the problem of the motion of the Moon relative to spatial irregularities in the interplanetary magnetic field is found. The lunar electrical conductivity is modeled by a two-layer conductivity profile. For the interaction of the Moon with the corotating sector structure of the interplanetary magnetic field it is found that the magnetic field in the lunar shell is the superposition of an oscillatory uniform field, an oscillatory dipole field and anoscillatory field that is toroidal about the axis of the motional electric field. With various lunar conductivity models and the theory of this paper, lunar surface magnetometer data can be quantitatively interpreted to yield information on the conductivity and consequently the temperature of the lunar core.Presently visiting the Max-Planck-Institut für Physik und Astrophysik, München, Germany.     

Energy flow and elemental concentrations in the Steina River ecosystem (Black Forest, Germany)

Considering food web energetics and elemental cycling together allows the testing of hypotheses about the coevolution of biological systems and their physical environment. We investigated the energy flow and the distribution of 25 elements in the Steina River.¶We constructed an annual energy flow network and estimated the emergy ("embodied energy" that includes all the energy involved in a process) contributions of resources sustaining the system. Furthermore, we measured the concentration of various macronutrients, essential elements, and heavy metals in the physical environment and trophic compartments. Finally, we examined the hypothesis of a positive relationship between the "rarity" of an element and its tendency to bioaccumulate. To do so, we used transformity, the relative energy input required to sustain a compartment's net production or the concentration differential of an element between the living community and the physical environment.¶The resulting energy flow network is one of the most complete available for streams. In the Steina, over 99% of the energy input is transported through the system without being processed. Dissolved inorganic matter and sunlight are the largest inputs, but uptake efficiency is much higher for dissolved and particulate organic matter. Transformities of trophic compartments and elements span 6 to 7 orders of magnitude.¶The tendency to bioaccumulate was as predicted for most elements, with macronutrients showing no accumulation and heavy elements accumulating in high-transformity compartments. However, Na and K were found at highest concentrations in consumers, and Pb, Ga, and Cd in algae. Improved estimates may become possible as more knowledge is available on ecosystem flows. We suggest further ways of testing hypotheses about strategies of element processing.     

Gradient theory of nucleation in polar fluids

Gradient theory (GT), a form of density functional theory (DFT), was applied to water, methanol, and ethanol using the cubic perturbed hard body (CPHB) equation of state (EOS). Compared to the standard form of classical nucleation theory (CNT), the GT results for water showed an improved temperature dependence, but the supersaturation dependence was slightly poorer. GT and several forms of CNT were also found to be in good agreement with a single high T molecular dynamics rate for TIP4P water. The rates predicted by GT for methanol and ethanol were improved by several orders of magnitude compared to CNT, but no improvement in the predicted temperature dependence of the rates was found.     

Calcium isotope fractionation in coccoliths of cultured Calcidiscus leptoporus, Helicosphaera carteri, Syracosphaera pulchra and Umbilicosphaera foliosa

Four species of marine calcifying algae, the coccolithophores Calcidiscus leptoporus, Helicosphaera carteri, Syracosphaera pulchra and Umbilicosphaera foliosa were grown in laboratory cultures under temperatures varying between 14 and 23 °C, and one species, C. leptoporus, under varying [CO₃²⁻], ranging from 105 to 219 μmol/kg. Calcium isotope compositions of the coccoliths resemble in both absolute fractionation and temperature sensitivity previous calibrations of marine calcifying species e.g. Emiliania huxleyi (coccolithophores) and Orbulina universa (planktonic foraminifera) as well as inorganically precipitated CaCO₃, but also reveal small species specific differences. In contrast to inorganically precipitated calcite, but similar to E. huxleyi and O. universa, the carbonate ion concentration of the medium has no statistically significant influence on the Ca isotope fractionation of C. leptoporus coccoliths; however, combined data of E. huxleyi and C. leptoporus indicate that the observed trends might be related to changes of the calcite saturation state of the medium. Since coccoliths constitute a significant portion of the global oceanic CaCO₃ export production, the Ca isotope fractionation in these biogenic structures is important for defining the isotopic composition of the Ca sink of the ocean, one of the key parameters for modelling changes to the marine Ca budget over time. For the present ocean our results are in general agreement with the previously postulated and applied mean value of the oceanic Ca sink (Δ_sed) of about − 1.3‰, but the observed inter- and intra-species differences point to possible changes in Δ_sed through earth history, due to changing physico-chemical conditions of the ocean and shifts in floral and faunal assemblages.     

A Sociodemographic and Partisan Analysis of Voting in Three Anti-Gay Rights Referenda in Oregon

Since 1988, three separate anti-gay rights referenda have been placed on the ballot in the state of Oregon. While in 1988 Oregon voters passed the first measure (subsequently found unconstitutional), they rejected similar referenda in 1992 and 1994. This paper examines the electoral geography of these three referenda both cartographically and quantitatively. It finds patterns of support for the referenda were closely associated with voting patterns for the Republican Party in gubernatorial and presidential elections, and with sociodemographic indicators reflective of traditionalist areas.     

Airborne gravimetry used in precise geoid computations by ring integration

Two detailed geoids have been computed in the region of North Jutland. The first computation used marine data in the offshore areas. For the second computation the marine data set was replaced by the sparser airborne gravity data resulting from the AGMASCO campaign of September 1996. The results of comparisons of the geoid heights at on-shore geometric control showed that the geoid heights computed from the airborne gravity data matched in precision those computed using the marine data, supporting the view that airborne techniques have enormous potential for mapping those unsurveyed areas between the land-based data and the off-shore marine or altimetrically derived data. Received: 7 July 1997 / Accepted: 22 April 1998     

Magnetospheric accretion and pre-main-sequence stellar masses

We present a method of determining lower limits on the masses of pre-main-sequence (PMS) stars and so constraining the PMS evolutionary tracks. This method uses the redshifted absorption feature observed in some emission-line profiles of T Tauri stars, indicative of infall. The maximum velocity of the accreting material measures the potential energy at the stellar surface, which, combined with an observational determination of the stellar radius, yields the stellar mass. This estimate is a lower limit owing to uncertainties in the geometry and projection effects. Using available data, we show that the computed lower limits can be larger than the masses derived from PMS evolutionary tracks for M   0.5 M. Our analysis also supports the notion that accretion streams do not impact near the stellar poles but probably hit the stellar surface at moderate latitudes.     

Development of longitudinal profiles of alluvial channels in response to base-level lowering

Degradation of alluvial channels in cohesive sediments was studied in 15 m and 20 m long flumes with a slope of 0°01 cm/cm. Degradation was initiated by lowering base level to a fixed position, and the development of the longitudinal profile of the channel is analysed through a model formulated as a heat (diffusion) equation. It is based on the equation of sediment continuity, combined with an assumption regarding sediment transport, namely that sediment discharge is linearly proportional to the channel slope. In accordance with the boundary and initial conditions imposed by the experimental setup and procedure, the basic equation is amenable to an analytical solution, which defines bed elevation at any distance and time, as a function of the amount of base-level lowering and a ‘diffusion’ coefficient. Additional problems arising from bank erosion and channel armouring are also treated successfully within the framework of the same model. The results show that in homogeneous alluvial sediments, not subject to armouring, the ultimate result of base-level lowering by a certain amount is degradation all along the channel by the same amount. The main impact of erosion is felt in the early stages after initiation of the process, and mainly near the mouth. The rate of degradation at any station along the channel reaches a peak and then slowly decreases with time, and the peak rate is attenuated with distance from the outlet. The model permits the prediction of intermediate stages of profile development at any distance from the outlet and at different times.     

Lunar glass compositions: Apollo 16 core sections 60002 and 60004

Approximately 500 glasses between 1 mm and 125 μm in size have been analyzed from fourteen samples from the Apollo 16 core sections 60002 and 60004. The majority of glasses have compositions comparable to those found in previous studies of lunar surface soils; however, two new and distinct glass compositions that are probably derived in part from mare material occur in the core samples. The major glass composition in all samples is that of Highland Basalt glass, but it also appears that high-K Fra Mauro Basalt (KREEP) glass is more common at the Apollo 16 site than was previously thought. The relative abundance of glasses within the core samples is random in distribution: each sample is characterized by a particular assemblage and distribution of the constituent glass compositions.     

Some chemographic relationships in n-component systems

A petrologic problem of fundamental importance is to determine whether 2 or more mineral assemblages can be related to one another by continuous or discontinuous facies changes, or whether their bulk compositions occupy non-overlapping regions of composition space. A general method is developed by which 2 regions of n-dimensional space whose vertices are defined by the phases present are tested for compositional overlap. This is accomplished by generating mass balance equations of the type:

$\text{∑}\text{i = 1}\text{m}\text{a}{}_{\mathrm{i}}\text{A}{}_{\mathrm{i}}\text{=}\text{∑}\text{j = 1}\text{k}\text{b}{}_{\mathrm{j}}\text{B}{}_{\mathrm{j}}$

where A_i is the ith phase in one region and B_j is the th phase in the other. If any such equation satisfies the requirement that the sign of each a_i is the same, and that the sign of each b_j is the opposite for all i, j such that: k + m = n + 1 then the 2 regions overlap in phase space.By eliminating all overlapping assemblages in a given set, the bivariant fields bounded by univariant equilibria in n-dimensional systems are completely specified. All bulk compositions are considered within the space defined by the phases that participate in the bounding reactions. An extension of the method generates in sequence all bivariant fields and associated reactions about any invariant point. A further extension is applied to multi-system analysis.