Decarbonising low grade heat for low carbon future

More energy is consumed in the UK for heat than either transport or electricity and yet until recently little attention has been given to decarbonising heat to meet the UK's 2050 greenhouse gas targets. The challenges are immense as over 80% of households in the UK use gas for space and water heating. To achieve the UK's greenhouse gas targets will necessitate heat to be almost completely decarbonised and will thus require a transition from gas for heating to a low carbon alternative. However, there is a lack of consensus over which low carbon heat technologies householders should be encouraged to adopt as projections of these vary significantly. This thesis commences by reviewing those projections and identifying the possible reasons for the variations. Low carbon heat technologies suitable for large scale deployment are identified and a heat demand model developed from which demand profiles can be constructed. An integrated heat and electricity investment model is then developed which includes electricity generation assets but also district heating assets such as combined heat and power plant, network storage and large network heat pumps. A core input into this model is the heat demand profiles. The investment model enables the interaction between heat and electricity assets to be evaluated and so using scenarios combined with sensitivities examines the economics and carbon emissions of the low carbon residential heating technologies previously identified. Throughout this analysis the equivalent cost for gas heating is used as a comparator. The results suggest that district heating is an attractive option which is robust under most outcomes. However, its economic viability is crucially dependent on a financing regime that is compatible with other network based assets. Also identified is a role for electric storage heaters for buildings with low heat demand.Open Acces

The nearshore cradle of early vertebrate diversification

Ancestral vertebrate habitats are subject to controversy and obscured by limited, often contradictory paleontological data. We assembled fossil vertebrate occurrence and habitat datasets spanning the middle Paleozoic (480 million to 360 million years ago) and found that early vertebrate clades, both jawed and jawless, originated in restricted, shallow intertidal-subtidal environments. Nearshore divergences gave rise to body plans with different dispersal abilities: Robust fishes shifted shoreward, whereas gracile groups moved seaward. Fresh waters were invaded repeatedly, but movement to deeper waters was contingent upon form and short-lived until the later Devonian. Our results contrast with the onshore-offshore trends, reef-centered diversification, and mid-shelf clustering observed for benthic invertebrates. Nearshore origins for vertebrates may be linked to the demands of their mobility and may have influenced the structure of their early fossil record and diversification

How directed is a directed network?

The trophic levels of nodes in directed networks can reveal their functional properties. Moreover, the trophic coherence of a network, defined in terms of trophic levels, is related to properties such as cycle structure, stability and percolation. The standard definition of trophic levels, however, borrowed from ecology, suffers from drawbacks such as requiring basal nodes, which limit its applicability. Here we propose simple improved definitions of trophic levels and coherence that can be computed on any directed network. We demonstrate how the method can identify node function in examples including ecosystems, supply chain networks, gene expression and global language networks. We also explore how trophic levels and coherence relate to other topological properties, such as non-normality and cycle structure, and show that our method reveals the extent to which the edges in a directed network are aligned in a global direction

Discriminating signal from noise in the fossil record of early vertebrates reveals cryptic evolutionary history

The fossil record of early vertebrates has been influential in elucidating the evolutionary assembly of the gnathostome bodyplan. Understanding of the timing and tempo of vertebrate innovations remains, however, mired in a literal reading of the fossil record. Early jawless vertebrates (ostracoderms) exhibit restriction to shallow-water environments. The distribution of their stratigraphic occurrences therefore reflects not only flux in diversity, but also secular variation in facies representation of the rock record. Using stratigraphic, phylogenetic and palaeoenvironmental data, we assessed the veracity of the fossil records of the jawless relatives of jawed vertebrates (Osteostraci, Galeaspida, Thelodonti, Heterostraci). Non-random models of fossil recovery potential using Palaeozoic sea-level changes were used to calculate confidence intervals of clade origins. These intervals extend the timescale for possible origins into the Upper Ordovician; these estimates ameliorate the long ghost lineages inferred for Osteostraci, Galeaspida and Heterostraci, given their known stratigraphic occurrences and stem–gnathostome phylogeny. Diversity changes through the Silurian and Devonian were found to lie within the expected limits predicted from estimates of fossil record quality indicating that it is geological, rather than biological factors, that are responsible for shifts in diversity. Environmental restriction also appears to belie ostracoderm extinction and demise rather than competition with jawed vertebrates

Colon contradictions: NF-κB signaling in intestinal tumorigenesis

No abstract available

Ichnofacies of the Stairway Sandstone fish-fossil beds (Middle Ordovician, Northern Territory, Australia)

The Stairway Sandstone is a 30-560 m thick succession of Middle Ordovician siliciclastic sedimentary rocks within the Amadeus Basin of central Australia, deposited in the epeiric Larapintine Sea of northern peri-Gondwana. The Stairway Sandstone is significant as one of only two known Gondwanan successions to yield articulated arandaspid (pteraspidomorph agnathan) fish. Herein we use the ichnology of the Stairway Sandstone to reveal insights into the shallow marine habitat of these early vertebrates, and compare it with that of other known pteraspidomorph-bearing localities from across Gondwana. The Stairway Sandstone contains a diverse Ordovician ichnofauna including 22 ichnotaxa of Arenicolites, Arthrophycus, Asterosoma, Cruziana, Didymaulichnus, Diplichnites, Diplocraterion,? Gordia, Lockeia, Monocraterion, Monomorphichnus, Phycodes, Planolites, Rusophycus, Skolithos and Uchirites. These ichnofauna provide a well-preserved example of a typical Ordovician epeiric sea assemblage, recording the diverse ethologies of tracemakers in a very shallow marine environment of flashy sediment accumulation and regularly shifting sandy substrates. New conodont data refine the age of the Stairway Sandstone to the early Darriwilian, with ichnostratigraphic implications for the Cruziana rugosa group and Arthrophycus alleghaniensis