A late pleistocene marine molluscan fauna from the Drifts of the Cheshire plain

Some recent finds from two working pits in the outwash sands of the Cheshire Plain are recorded. The opportunity is taken to discuss the dating and ecology of the fauna in relation to past and present theories of environment in the late Pleistocene, and their relationship to the fauna of the Macclesfield New Cemetery Beds.     

Photometric Variability of Neptune, 1972-2000

We present Strömgren b (472-nm) and y (551-nm) photometry of Neptune based on photoelectric measurements obtained at every apparition from 1972 to 2000. Neptune has brightened by 11% in b and 10% in y since 1980 with most of the increase occurring after 1990. By appending b data to published B magnitudes measured at Lowell from 1950 to 1966 and transformed to b, we show that Neptune is now brighter than at any time during the past half century. The nature of the year-to-year variations changed around 1990 when a steady rising trend overshadowed what appeared to be an inverse correlation with cyclic solar activity. By matching observations in b and y with near-infrared J (1.2-μm) and K (2.2-μm) photometry before, during, and after Neptune's 1976 infrared outburst, we show that the pattern of visible albedo variation parallels the infrared variation but with an amplitude 20-50 times smaller. A detailed comparison of photometry with ground-based and Voyager images at visible and red wavelengths during the 1989 Voyager encounter shows that small brightness variations occur when large discrete features rotate across Neptune's disk. This provides a rough association between visible features and photometric effects that we use to infer the state of Neptune's atmosphere for years when only photometry was available. A year-by-year analysis of variance of the photometry suggests that the 1976 and 1986-1989 infrared outbursts were isolated episodes of unusually vigorous atmospheric activity. Detrended magnitudes of Neptune are correlated with solar activity over the entire 29-year interval as well as 22-year subintervals, with solar UV now being favored as a causative mechanism rather than solar modulated galactic cosmic rays.     

The Aristarchus-Harbinger region of the moon: Surface geology and history from recent remote-sensing observations

The region including the Aristarchus Plateau and Montes Harbinger is probably the most diverse, geologically, of any area of comparble size on the Moon. This part of the northwest quadrant of the lunar near side includes unique dark mantling material; both the densest concentration and the largest of the sinuous rilles; apparent volcanic vents, sinks, and domes; mare materials of various ages and colors; one of the freshest large craters (Aristarchus) with ejecta having unique colors and albedos; and three other large craters in different states of flooding and degradation (krieger, Herodotus, and Prinz). The three best-authenticated lunar transient phenomena were also observed here.This study is based principally on photographic and remote sensing observations made from Earth and Apollo orbiting space craft. Results include (1) delineation of geologic map units and their stratigraphic relationships; (2) discussion of the complex interrelationships between materials of volcanic and impact origin, including the effects of excavation, redistribution and mixing of previously deposited materials by younger impact craters; (3) deduction of physical and chemical properties of certain of the geologic units, based on both the remote-sensing information and on extrapolation of Apollo data to this area; and (4) development of a detailed geologic history of the region, outlining the probable sequence of events that resulted in its present appearance.A primary concern of the investigation has been anomalous red dark mantle on the Plateau. Based on an integration of Earth- and lunar orbit-based data, this layer seems to consist of fine-grained, block-free material containing a relatively large fraction of orange glass. It is probably of pyroclastic origin, laid down at some time during the Imbrian period of mare flooding.     

Spatial Pair-Copula Modeling of Grade in Ore Bodies: A Case Study

A real-world mining application of pair-copulas is presented to model the spatial distribution of metal grade in an ore body. Inaccurate estimation of metal grade in an ore reserve can lead to failure of a mining project. Conventional kriged models are the most commonly used models for estimating grade and other spatial variables. However, kriged models use the variogram or covariance function, which produces a single average value to represent the spatial dependence for a given distance. Kriged models also assume linear spatial dependence. In the application, spatial pair-copulas are used to appropriately model the non-linear spatial dependence present in the data. The spatial pair-copula model is adopted over other copula-based spatial models since it is better able to capture complex spatial dependence structures. The performance of the pair-copula model is shown to be favorable compared to a conventional lognormal kriged model.     

Magnetic remanence acquisition in Finnish lake sediments

Summary. Magnetic studies have been carried out on organic sediments from five Finnish lakes to determine the carrier(s) of the stable NRM and to find how the remanence is acquired. Single or pseudo-single domain 'magnetite' is thought to carry the NRM. It was found that drying and cooling sediment samples resulted in a loss of NRM which was attributed to the misalignment of small magnetic particles. Low-field experiments were carried out on sediment samples in different physical states and from the results of these investigations it was concluded that post-depositional processes are important in the acquisition of an NRM. Stabilization of magnetic grains is thought to be due to the growth of gels in the organic sediment rather than to dewatering.     

Making ends meet, in the household and on the planet

Policy-making in relation to sustainable development is usually at the national (or, in relation to climate change, the global) level, yet the consumption it seeks to modify takes place at the household level. If households all ‘made ends meet’ in the same way then the much-relied upon notion of per capita consumption would be valid and we could rely on ‘top-down’ modelling to guide policy. Cultural Theory, however, predicts that there are five socially viable ways of making ends meet, and that all of them will be found (in varying proportions) within any nation. This prediction has been tested on a sample of 220 British households and shown to be well supported. Top-down modelling, it is argued, has to give way to a constructive interplay between the reflexive policy-maker and a plurally responsive citizenry. This revised version was published online in August 2006 with corrections to the Cover Date.     

Characterisation of water masses and phytoplankton nutrient limitation in the East Australian Current separation zone during spring 2008

This study focuses on the comparison of oceanic and coastal cold-core eddies with inner-shelf and East Australian Current (EAC) waters at the time of the spring bloom (October 2008). The surface water was biologically characterised by the phytoplankton biomass, composition, photo-physiology, carbon fixation and by nutrient-enrichment experiments. Marked differences in phytoplankton biomass and composition were observed. Contrasted biomarker composition suggests that biomarkers could be used to track water masses in this area. Divinyl chlorophyll a, a biomarker for tropical Prochlorophytes, was found only in the EAC. Zeaxanthin a biomarker for Cyanophytes, was found only within the oceanic eddy and in the EAC, whereas chlorophyll b (Chlorophytes) was only present in the coastal eddy and at the front between the inner-shelf and EAC waters.This study showed that cold-core eddies can affect phytoplankton, biomass, biodiversity and productivity. Inside the oceanic eddy, greater phytoplankton biomass and a more complex phytoplankton community were observed relative to adjacent water masses (including the EAC). In fact, phytoplankton communities inside the oceanic eddy more closely resembled the community observed in the inner-shelf waters. At a light level close to half-saturation, phytoplankton carbon fixation (gC d⁻¹) in the oceanic eddy was 13-times greater than at the frontal zone between the eddy and the EAC and 3-times greater than in the inner-shelf water. Nutrient-enrichment experiments demonstrated that nitrogen was the major macronutrient limiting phytoplankton growth in water masses associated with the oceanic eddy. Although the effective quantum yield values demonstrate healthy phytoplankton communities, the phytoplankton community bloomed and shifted in response to nitrogen enrichments inside the oceanic eddy and in the frontal zone between this eddy and the EAC. An effect of Si enrichment was only observed at the frontal zone between the eddy and the EAC. No response to nutrient enrichment was observed in the inner-shelf water where ambient NO_x, Si and PO₄ concentrations were up to 14, 4 and 3-times greater than in the EAC and oceanic eddy. Although results from the nutrient-enrichment experiments suggest that nutrients can affect biomass and the composition of the phytoplankton community, the comparison of all sites sampled showed no direct relationship between phytoplankton biomass, nutrients and the depth of the mixed layer. This is probably due to the different timeframe between the rapidly changing physical and chemical oceanography in the separation zone of the EAC.     

Automated threshold selection methods for extreme wave analysis

The study of the extreme values of a variable such as wave height is very important in flood risk assessment and coastal design. Often values above a sufficiently large threshold can be modelled using the Generalized Pareto Distribution, the parameters of which are estimated using maximum likelihood. There are several popular empirical techniques for choosing a suitable threshold, but these require the subjective interpretation of plots by the user.In this paper we present a pragmatic automated, simple and computationally inexpensive threshold selection method based on the distribution of the difference of parameter estimates when the threshold is changed, and apply it to a published rainfall and a new wave height data set. We assess the effect of the uncertainty associated with our threshold selection technique on return level estimation by using the bootstrap procedure. We illustrate the effectiveness of our methodology by a simulation study and compare it with the approach used in the JOINSEA software. In addition, we present an extension that allows the threshold selected to depend on the value of a covariate such as the cosine of wave direction.