High concentration of 28,30-bisnorhopane and 25,28,30-trisnorhopane at the PETM in the Faroe-Shetland basin

Petroleum exploration in the Faroe-Shetland basin has resulted in the drilling of wells some of which contain expanded sections across the Palaeocene Eocene thermal maximum event (PETM). Here we present data from a Faroe – Shetland Basin well. Samples analysed have a mixture of terrestrial and marine inputs. PETM events, are recorded in both bulk and compound specific carbon isotope excursions of 2-3'. In addition, the PETM is marked by a change in palynology and we have observed changes in the distribution of biomarkers across the PETM and recognise a sharply defined spike in 25,28,30- trisnorhopane (TNH) and 28,30-bisnorhopane (BNH) concentrations at the PETM boundary. Firstly, while we have been able to identify variation in a range of compounds present in the core, their variation reassuringly mostly follow associated palynological changes. Demethylated hopanes 28,30-bisnorhopane (BNH) and 25,28,30-trisnorhopane (TNH), are present in relatively low concentrations just below and above the carbon isotope excursion (CIE), but in high concentrations at the PETM (Fig 1). The actual bacteria responsible for TNH and BNH in geological samples has so far not been determined [1]. However, BNH and TNH are thought to be produced by chemoautotrophic bacteria, their presence in rocks which formed in inner neritic environments may indicate strong upwelling or perhaps ocean overturn. Extreme shallowing of the CCD is well documented at the PETM, but there has previously been no clear indicator for a potential ocean overturn, although this has previously been mentioned as a potential driver for the event. While this has been dismissed as a mechanism driving the PETM events because it was envisaged as a local basin overturn, and can not explain the global extent of the PETM [2], we propose that the presence of TNH and BNH indicates ocean overturn may have played a role in the PETM. While it may not explain the isotopically light carbon in its entirety, stratification and ocean overturn may be a consequence of high temperatures, since palynological evidence indicates very low salinity conditions in surface waters at the PETM

How to Measure Group Selection in Real-world Populations

Multilevel selection and the evolution of cooperation are fundamental to the formation of higher-level organisation and the evolution of biocomplexity, but such notions are controversial and poorly understood in natural populations. The theoretic principles of group selection are well developed in idealised models where a population is neatly divided into multiple semi-isolated sub-populations. But since such models can be explained by individual selection given the localised frequency-dependent effects involved, some argue that the group selection concepts offered are, even in the idealised case, redundant and that in natural conditions where groups are not well-defined that a group selection framework is entirely inapplicable. This does not necessarily mean, however, that a natural population is not subject to some interesting localised frequency-dependent effects – but how could we formally quantify this under realistic conditions? Here we focus on the presence of a Simpson’s Paradox where, although the local proportion of cooperators decreases at all locations, the global proportion of cooperators increases. We illustrate this principle in a simple individual-based model of bacterial biofilm growth and discuss various complicating factors in moving from theory to practice of measuring group selection

The Efficacy of Group Selection is Increased by Coexistence Dynamics within Groups

Selection on the level of loosely associated groups has been suggested as a route towards the evolution of cooperation between individuals and the subsequent formation of higher-level biological entities. Such group selection explanations remain problematic, however, due to the narrow range of parameters under which they can overturn within-group selection that favours selfish behaviour. In principle, individual selection could act on such parameters so as to strengthen the force of between-group selection and hence increase cooperation and individual fitness, as illustrated in our previous work. However, such a process cannot operate in parameter regions where group selection effects are totally absent, since there would be no selective gradient to follow. One key parameter, which when increased often rapidly causes group selection effects to tend to zero, is initial group size, for when groups are formed randomly then even moderately sized groups lack significant variance in their composition. However, the consequent restriction of any group selection effect to small sized groups is derived from models that assume selfish types will competitively exclude their more cooperative counterparts at within-group equilibrium. In such cases, diversity in the migrant pool can tend to zero and accordingly variance in group composition cannot be generated. In contrast, we show that if within-group dynamics lead to a stable coexistence of selfish and cooperative types, then the range of group sizes showing some effect of group selection is much larger

Utilising a fieldbus protocol in a water quality monitoring system

This thesis presents a new water quality monitoring system developed at the University of Durham in conjunction with Partech Instruments Ltd. The system uses a fieldbus protocol to create an open, distributed control network, replacing the dedicated products currently offered. Echelon LonWorks has been used to create three nodes: a suspended solids sensor, a general-purpose interactive monitoring tool, and a universal relay setpoint module. When connected, these nodes provide a means of activating relays when the suspended solids level reaches a definable level, while providing a numerical display for the operator. The sensor may be calibrated for a number of different applications. The sensor uses infra-a-red light to monitor the light absorption and 90 scatter within the solution. By dynamically adjusting the intensity of the emitted light, the sensor is able to increase its range over conventional devices. Signal processing, linearization and calibration operations are carried out within the sensor software. The final measurement is communicated as a LonWorks network variable, allowing the sensor to be treated as an interoperable device. Several third-party products have been connected to the network and a high degree of interoperability demonstrated. Three network management software packages have been investigated, and their suitability assessed. The final prototype system shows the power, flexibility and cost-saving that a fieldbus protocol can provide in an industrial control environment

Cosmological Moduli Dynamics

Low energy effective actions arising from string theory typically contain many scalar fields, some with a very complicated potential and others with no potential at all. The evolution of these scalars is of great interest. Their late time values have a direct impact on low energy observables, while their early universe dynamics can potentially source inflation or adversely affect big bang nucleosynthesis. Recently, classical and quantum methods for fixing the values of these scalars have been introduced. The purpose of this work is to explore moduli dynamics in light of these stabilization mechanisms. In particular, we explore a truncated low energy effective action that models the neighborhood of special points (or more generally loci) in moduli space, such as conifold points, where extra massless degrees of freedom arise. We find that the dynamics has a surprisingly rich structure - including the appearance of chaos - and we find a viable mechanism for trapping some of the moduli.Comment: 35 pages, 14 figures, references adde

Investigating the structure of the autism-spectrum quotient using Mokken scaling

Traits similar to those shown in autism spectrum condition (ASC) are apparent in relatives of individuals with ASC, and in the general population without necessarily meeting diagnostic criteria for an ASC. We assess whether the Autism-Spectrum Quotient (AQ), a self-report measure, has hierarchical properties using Mokken scaling. Hierarchical scales allow the presence of a latent trait to be identified by discovering whether and how many specific items form an ordered array along it. Data were collected from 2 groups: (1) people with ASC (n = 449: 240 males, 209 females, M age 35.4 years, SD = 12.8) and (2) university students (n = 943: 465 males, 475 females, M age = 23.0 years, SD = 8.4). A single Mokken scale was obtained in the data from university students and 3 scales were obtained in the data from people with ASC. The scales all showed moderate Mokken scaling properties with the single scale obtained from university students showing weak invariant item ordering and 2 of the scales from people with ASC showing weak invariant item ordering. The AQ formed reliable Mokken scales. There was a large overlap between the scale from the university student sample and the sample with ASC, with the first scale, relating to social interaction, being almost identical. The present study confirms the utility of the AQ as a single instrument that can dimensionalize autistic traits in both university student and clinical samples of ASC, and confirms that items of the AQ are consistently ordered relative to one another

Quantifying the variability of wind energy

Wind by its very nature is a variable element. Its variation is different on different timescales and spatially its magnitude can change dramatically depending on local climatology and terrain. This has implications in a variety of sectors, not least in the wind energy sector. The accuracy of weather forecasting models has increased significantly in the last few decades and these models are able to give an insight into variability on the hourly and daily timescales. On shorter timescales, predicting chaotic turbulent fluctuations is far more challenging. Similarly, the ability to make seasonal forecasts is extremely limited. General circulation models (GCMs) can give insights into possible future decadal fluctuations, but there are still large uncertainties. Observational data can give useful information concerning variation on a variety of timescales, but data quality and spatial coverage can be variable. An understanding of local scale spatial variations in wind is extremely important in wind farm siting. In the last 40 years, there have been significant advances in predicting these variations using computer models, although there remain significant challenges in understanding the behavior of the wind in certain environments. Both the spatial and temporal variations of wind are important considerations when wind power is integrated into electricity networks, and this will become an ever more important consideration as wind generation makes an increasing contribution to our global energy needs

Organic geochemistry of the Boltysh impact crater, Ukraine

The Boltysh crater has been know for several decades and was originally drilled in the 1960s - 1980s in a study of economic oil shale deposits. Unfortunately, the cores were not curated and have been lost. However we have recently re-drilled the impact crater and have recovered a near continuous record of ~400m of organic rich sediments deposited in a deep isolated lake which overly the basement rocks spanning a period ~10 Ma. The Boltysh impact crater, centred at 48°54–N and 32°15–E is a complex impact structure formed on the basement rocks of the Ukrainian shield. The age of the impact is 65.17±0.64 Ma [1]. At 24km diameter, the impact is unlikely to have contributed substantially to the worldwide devastation at the end of the Cretaceous. However, the precise age of the Boltysh impact relative to the Chicxulub impact and its location on a stable low lying coastal plain which allowed formation of the postimpact crater lake make it a particularly important locality. After the impact, the crater quickly filled with water, and the crater lake received sediment input from the surrounding land surface for a period >10 Ma [2]. These strata contain a valuable record of Paleogene environmental change in central Europe, and one of very few terrestrial records of the KT event. This preeminent record of the Paleogene of central Europe can help us to answer several related scientific questions. What is the relative age of Boltysh compared with Chicxulub? How long was the hydrothermal system active for after the impact event? How did the devastated area surrounding the crater recover, and how rapid was the recovery? The first sediments to be deposited in the crater lake were a series of relatively thin turbidites, the sediments then become organic rich shales and oil shales. Within the core there is ~400 m of organic rich shales/oil shales spanning a period of ~10 Ma some of which contain macrofossils such as ostracods, fish and plant fossils. Preliminary palynological studies suggest initial sedimentation was slow after the impact followed by more rapid sedimentation through the Late Paleocene. Hydrocarbons extracted from these samples are commonly dominated by terrestrial n-alkanes (Fig 1), Hopanes (including 3-methylhopanes) and steranes are also abundant and indicate the immaturity of the samples. The immaturity of samples is also evident from the abundance of hopenes, sterenes and oleanenes especially in the upper section of the core. In some of the oil shales the hopenes and sterenes are the most abundant hydrocarbons present. There is variation in the distribution of hydrocarbons/biomarkers and palynology throughout the core caused by changing inputs and environmental conditions