Measurement of the lunar neutron density profile

Anin situ measurement of the lunar neutron density from 20 to 400 g cm^?2 depth below the lunar surface was made by the Apollo 17 Lunar Neutron Probe Experiment (LNPE) using particle tracks produced by the¹⁰B (n,α)⁷Li reaction. Both the absolute magnitude and the depth profile of the neutron density are in good agreement with theoretical calculations by Lingenfelter, Canfield, and Hampel. However, relatively small deviations between experiment and theory in the effect of Cd absorption on the neutron density and in the relative¹⁴⁹Sm to¹⁵⁷Gd capture rates reported previously (Russet al., 1972) imply that the true lunar¹⁵⁷Gd capture rate is about one half of that calculated theoretically.     

Axially-symmetric Velocities in the 15 May 2000 Eruptive Prominence

Large Doppler velocities with unique, almost regular elliptical features were observed in the H spectra of the May 15, 2000 eruptive prominence. These features were interpreted in the frame of axially symmetric models of the eruptive prominence. The rotational (7–60 km s^–1), expansion (30–44 km s^–1), axial (3–19 km s^–1), and global (66–160 km s^–1) prominence plasma velocities were derived. The plasma velocity patterns were compared with the observed helical structures of the H prominence. The velocities of selected H blobs in the image plane were determined. The axially symmetric detwisting process of the magnetic flux rope of the eruptive prominence was recognized.     

A granite–gabbro complex from Madagascar: constraints on melting of the lower crust

The Ranomandry Complex is a Neoproterozoic, nested intrusion from central Madagascar composed of a gabbroic core within a coeval peraluminous granite ring intruding pelitic metasediments. Although xenocryst entrainment and magma mixing have both contributed to marginal phases of the granite, the primary melt is characterised by steep LREE/HREE ratios and negligible, or slightly positive, Eu anomalies. Both isotopic and trace element systematics preclude an origin from either partial melting of the metapelitic country rock or from fractional crystallisation of the gabbroic magma. However, trace-element modelling suggests an origin from the dehydration melting of a plagioclase-poor, garnet-bearing metagreywacke at temperatures of 850–900 °C and at lower crustal pressures (>10 kbar). Melting of an enriched subcontinental mantle generated gabbroic magmas that caused advective heating and anatexis at the base of thickened continental crust during their ascent. Transport of the resulting granite magma was facilitated by the pre-existing plumbing system that overcame thermal and mechanical problems associated with both diapirism and self-propagating dykes as mechanisms for long-distance transport of granite magmas. The nested geometry of the intrusions is an indication of a structurally homogeneous lower crust that contains no pre-existing shear zones or fault systems.     

Gradient Estimation from Irregularly Spaced Data Sets

Topographic data sets are often composed of terrain samples arranged in irregular meshes. Many gradient estimation methods require the data to be arranged in a regular mesh; irregular meshes present a difficulty for them. This paper presents a novel method of estimating surface gradients from irregularly spaced inputs. The method is derived using directional derivatives and is shown to be a generalization of traditional finite difference methods. Analytical tests were used to evaluate the method, which was shown to be accurate and robust.     

Radiographic study of the distribution of boron in recent mollusc shells

Studies have been made of the boron content and distribution in recent Mytilus edulis shells by mapping the alpha particle distribution produced by the ¹⁰B (n,α)⁷Li reaction using cellulose nitrate track detectors. Boron is concentrated in the inorganic parts of the shell matrix and is enriched in aragonite relative to calcite by a factor of 1.5–2. The B contents in different parts of individual shells and in different specimens from a given locality are well defined, particularly for the aragonite layer. A correlation was found between the B in the aragonite layer and the salinity of the water in which the shells grew. The method shows promise as a means of using the boron content of fossil shells to determine paleosalinity.     

Projection of auroral intensity contours into the magnetosphere

Isointensity contours of 630 nm auroral emission are traced into the magnetosphere, using two different empirical magnetic field models, the Mead-Fairfield model, and the Hedgecock-Thomas model. The auroral data are for a specific ISIS-II satellite pass, and so the starting points are expressed in geographic latitude and longitude coordinates, at a specific universal time. The magnetic field models are constructed from satellite magnetometer measurements, and those used correspond to magnetically quiet times. The projections are found to agree reasonably well with direct plasma measurements of the plasma sheet. The projections of the dayside contour connect to widely different regions of the magnetosphere, providing an interpretation that is consistent with observations of the dayside aurora. It is concluded that field line projections of the aurora into the magnetosphere using these models is a valid procedure, but only under quiet-time conditions.     

Methodological Aspects of the Tolerable Windows Approach

The tolerable windows approach (TWA) allows the climate policyformulation process to be safeguarded in the following way. First,guardrails are defined in order to exclude intolerable climatechange impacts, on the one hand, and unacceptable socioeconomicconsequences of climate change mitigation measures, on the other.Second, a scientific analysis is conducted to investigate thefeatures of those emission paths that are compatible with theguardrail constraints. The fundamental methodology of the TWA isbest described in terms of the theory of differentialinclusions. This emerging mathematical theory already providesnumerical methods applicable as long as the underlying integratedassessment models are of limited complexity. In order to identifyemissions corridors, we propose a novel calculation schemeapplicable also for large-scale integrated assessment models.     

Dynamical System Analysis and Forecasting of Deformation Produced by an Earthquake Fault

— We present a method of constructing low-dimensional nonlinear models describing the main dynamical features of a discrete 2-D cellular fault zone, with many degrees of freedom, embedded in a 3-D elastic solid. A given fault system is characterized by a set of parameters that describe the dynamics, rheology, property disorder, and fault geometry. Depending on the location in the system parameter space, we show that the coarse dynamics of the fault can be confined to an attractor whose dimension is significantly smaller than the space in which the dynamics takes place. Our strategy of system reduction is to search for a few coherent structures that dominate the dynamics and to capture the interaction between these coherent structures. The identification of the basic interacting structures is obtained by applying the Proper Orthogonal Decomposition (POD) to the surface deformation fields that accompany strike-slip faulting accumulated over equal time intervals. We use a feed-forward artificial neural network (ANN) architecture for the identification of the system dynamics projected onto the subspace (model space) spanned by the most energetic coherent structures. The ANN is trained using a standard back-propagation algorithm to predict (map) the values of the observed model state at a future time, given the observed model state at the present time. This ANN provides an approximate, large-scale, dynamical model for the fault. The map can be evaluated once to provide a short-term predictions or iterated to obtain a prediction for the long-term fault dynamics.     

The significance of channel recharge rates for estimating debris‐flow magnitude and frequency

The quantification of debris‐flow hazard requires estimates of debris‐flow frequency and magnitude. Several methods have been proposed to determine the probable volume of future debris flows from a given basin, but most have neglected to account for debris recharge rates over time, which may lead to underestimation of debris‐flow volumes in basins with rare debris flows. This paper deals with the determination of debris recharge rates in debris‐flow channels based on knowledge of debris storage and the elapsed time since the last debris flow. Data are obtained from coastal British Columbia and a relation is obtained across a sample of basins with similar terrain and climatic conditions. For Rennell Sound on the west coast of the Queen Charlotte Islands, the power‐law relation for area‐normalized recharge rate, R_t, versus elapsed time, t_e was R_t = 0·23t_e^?0·58 with an explained variance of 75 per cent. A difference in recharge rates may exist between creeks in logged and unlogged forested terrain. The power function for undisturbed terrain was R_t = 0·20t_e^?0·49, while the function for logged areas was R_t = 0·30t_e^?0·77. This result suggests that for the same elapsed time since the last debris flow, clearcut gullies tend to recharge at a slower rate than creeks in old growth forest. This finding requires verification, particularly for longer elapsed times since debris flow, but would have important implications for forest resource management in steep coastal terrain. This study demonstrates that commonly used encounter probability equations are inappropriate for recharge‐limited debris flow channels. Copyright © 2005 John Wiley & Sons, Ltd.