Dynamics of COVID-19 epidemics: SEIR models underestimate peak infection rates and overestimate epidemic duration

Compartment models of infectious diseases, such as SEIR, are being used extensively to model the COVID-19 epidemic. Transitions between compartments are modelled either as instantaneous rates in differential equations, or as transition probabilities in discrete time difference or matrix equations. These models give accurate estimates of the position of equilibrium points, when the rate at which individuals enter each stage is equal to the rate at which they exit from it. However, they do not accurately capture the distribution of times that an individual spends in each compartment, so do not accurately capture the transient dynamics of epidemics. Here we show how matrix models can provide a straightforward route to accurately model stage durations, and thus correctly reproduce epidemic dynamics. We apply this approach to modelling the dynamics of a COVID-19 epidemic. We show that a SEIR model underestimates peak infection rates (by a factor of three using published parameter estimates based on the progress of the epidemic in Wuhan) and substantially overestimates epidemic persistence after the peak has passed

Implications of climate change for coastal and inter-tidal habitats in the UK

Coastal habitats are diverse and vary in the extent to which they are shaped by physiographic processes, such as wave action, wind, tides and sediment availability, and the relative influence of terrestrial and marine environments, e.g. tidal inundation versus groundwater levels. Coastal systems usually comprise mosaics of habitats that are functionally interdependent: for instance, saltmarsh may form behind a barrier island or shingle ridge that itself may also support a dune system; or estuaries may include a range of habitats that ultimately depend on sediment supply from the catchment and the mixing of fresh and saline waters. Coastal grazing marsh is a man-made, largely freshwater habitat, occurring landward of intertidal and coastal habitats and protected from them by natural or man-made structures. Whilst grazing marsh and other coastal habitats are not strictly functionally interdependent, there are significant conflicts between protecting grazing marsh and allowing landward movement of coastal habitats

Biodiversity climate change impacts report card technical paper:10. Implications of climate change for coastal and inter-tidal habitats in the UK

Executive summary - Coastal habitats are complex, dynamic and interdependent. They are important in providing sea defences, areas for recreation, biodiversity and a range of other ecosystem services. - Increased air- and sea-surface temperatures have resulted in changes in the distribution of marine and coastal species. Both warmer- and colder-water species are shifting northwards. However, warmer-water species are shifting northwards faster than colder-water species are retreating, resulting in changes in community composition. Changes in the abundance of keystone taxa can cause a cascade of responses, further altering community composition. - Changes in the phenology of coastal species have been observed, with the rates of change in marine species being considerably greater than those in terrestrial and freshwater systems. Recent advances in the phenology of species have not all occurred at the same rate, in some cases resulting in mismatches of timing of annual cycles of animals and their food organisms. - Changes in precipitation are likely to affect coastal habitats, but the projected increase in winter rainfall and decrease in summer rainfall will tend to have opposing effects; the net result of these is not known. High winter rainfall and milder winter temperatures may extend the growing season and lead to faster succession and dominance by taller competitive plant species. This will be exacerbated by anthropogenic nutrient enrichment. However, increasing frequency and severity of summer droughts may counteract the effects of nutrient enrichment and winter precipitation. Increased drought will have impacts on habitats that are highly dependent on the maintenance of hydrological regimes, such as machair lochs and dune slacks. - Rising sea levels have been associated with the loss of coastal habitats. Predicted future rises will have significant impacts on coastal and intertidal habitats, including changing geomorphological processes, further habitat loss and increasing the vulnerability of infrastructure. However, coastal systems are dynamic and have the potential to adapt to rising sea levels, but only if there is an adequate supply of sediment to allow accretion and if there is landward space for the coast to roll-back into. Sea defences and other coastal management interrupt the movement of sediment between systems and prevent natural coastal realignment. - Managed coastal realignment is beneficial because it offers the potential to create habitat and provide flood defence benefits. Inevitably, there will be conflict between the need to maintain intertidal and other coastal habitats (e.g. saltmarsh, mud flat and sand dune) by realignment, and the need to protect valuable inland coastal habitats, such as grazing marsh and saline lagoons. - Future changes in coastal habitats are hard to predict because it is difficult to separate the impacts of rising sea levels from those of coastal management, including sea defences. Coastal zone management and adaptation, and the interactions with other climate drivers, nutrient deposition and habitat management, will have significant influence on the quantity, quality and location of future coastal habitats

The linear CS/WZW bulk/boundary system in AQFT

This paper constructs in the framework of algebraic quantum field theory (AQFT) the linear Chern-Simons/Wess-Zumino-Witten system on a class of $3$-manifolds $M$ whose boundary $\partial M$ is endowed with a Lorentzian metric. It is proven that this AQFT is equivalent to a dimensionally reduced AQFT on a $2$-dimensional manifold $B$, whose restriction to the $1$-dimensional boundary $\partial B$ is weakly equivalent to a chiral free boson.Comment: 32 page

Finding new meaning for old values: Aboriginal cultural tourism planning in and adjacent to protected areas

My doctoral research with the Girringun Aboriginal Corporation on Country-based tourism planning and management in the Wet Tropics World Heritage Area explores applications of traditional knowledge within Aboriginal tourism and the real or imagined barriers to its recognition by the broader tourism industry and tourism managers as an essential linkage between Indigenous peoples and their environments. Education/tourism activities on Country may be one of the few ways to preserve knowledge as a lived-experience, as the culture surrounding traditional hunting and access to Country in protected areas evolves. This research has been strongly influenced by senior Jirrbal Elder, Ernie Grant, whose holistic planning and education framework has been adopted by the Queensland Department of Education as a model for cross-cultural education. His style of cultural education at Echo Creek can be viewed as a model of best-practice rainforest tourism, in which traditional knowledge, cultural transmission, and ecosystem and Indigenous wellbeing are indivisible. This holistic approach has the potential for broader application in developing participatory approaches to cultural awareness for a range of protected area stakeholders, including managers and the tourism industry

Obstructions to the existence of M{\o}ller maps

M{\o}ller maps are identifications between the observables of a perturbatively interacting physical system and the observables of its underlying free (i.e. non-interacting) system. This work studies and characterizes obstructions to the existence of such identifications. The main results are existence and importantly also non-existence theorems, which in particular imply that M{\o}ller maps do not exist for non-Abelian Chern-Simons and Yang-Mills theories on globally hyperbolic Lorentzian manifolds.Comment: v2: Introduction updated and references added. 26 page

The Effect of Cell Volume on Mammary Gland Metabolism

1. It is becoming increasingly apparent that cell volume, otherwise termed the cellular hydration state, regulates processes such as protein synthesis, lipogenesis and membrane transport. In this study, the effect of cell volume perturbations on mammary cell metabolism has been investigated. Thus, the effect of cell swelling and shrinking on protein synthesis and lipogenesis in rat mammary tissue has been examined. In addition, the effect of cell volume changes on the free cytosolic calcium concentration ([Ca2+]i) in rat mammary acinar cells has been studied. 2. Mammary tissue (explants and acini) isolated from lactating rats during peak lactation was used in this study. Protein synthesis was studied by measuring the incorporation of radiolabelled amino acids into trichloroacetic acid precipitable material. Cell swelling, induced by a hyposmotic shock markedly increased protein synthesis in mammary tissue explants and acini. Conversely, cell shrinking, induced by a hyperosmotic shock markedly inhibited protein synthesis in mammary explants and acini. The effect of cell swelling and shrinking on protein synthesis was a) dependent upon the extent of the osmotic challenge and b) reversible. Swelling- induced mammary protein synthesis was dependent upon the presence of extracellular calcium. In this connection, thapsigargin and tBHQ markedly inhibited volume- sensitive protein synthesis suggesting that protein synthesis is dependent upon luminal calcium stores. Isosmotic cell swelling, induced by using buffers containing urea significantly increased mammary protein synthesis. 3. The effect of cell volume perturbations on the [Ca2+]i in mammary acinar cells isolated from rats during peak lactation was examined. The [Ca2+]i was measured using the fura-2 dye technique. Cell swelling, induced by a hyposmotic challenge, increased the [Ca2+]i in a fashion that was transient. The effect of a hyposmotic shock on the [Ca2+]i was dependent upon the extent of the osmotic perturbation. The hyposmotically-induced increase in the [Ca2+]i could not be attributed to a) a change in the trans-membrane sodium gradient or b) a change in the ionic strength of the incubation buffer. Removing extracellular Ca2+ (using EGTA) inhibited the effect of a hyposmotic shock on the [Ca2+]i in rat mammary acinar cells, suggesting that a hyposmotic challenge increases the influx of Ca2+ rather than a release of Ca2+ from intracellular stores Thapsigargin increased the size of the volume-sensitive increase m the [

Liveweight gain per head and per ha throughout the year of lambs grazing conventional pastures and those that switch from grass to clover

Intensive lamb finishing requires a consistent supply of high quality forage throughout the year to regularly finish lambs. Per head and per ha liveweight gain of weaned lambs was compared in 13 batches of lambs on replicated irrigated farmlets for 2.5 years from conventional mixed tetraploid perennial ryegrasswhite clover pastures (Conv) and pastures that were pure white clover for spring and summer and switched to overdrilled Italian ryegrass for the winter (Switch). Seasonal differences in stocking rate (lambs/ha), liveweight gain per head and per ha were significant (P<0.05). Average daily liveweight gain/ha was significantly higher (6.01 versus 5.66 kg/ha/day for Switch and Conv, respectively, but the total grazing days were slightly lower on the Switch farmlets resulting in similar annualised liveweight gain per ha (1 800 kg) and net carcass weight (800 kg/ha) on both pasture treatments. The farmlets apparently utilised 10 000 kg DM/ha/yr of the 16 000 kg DM accumulated.This work was funded by an internal Lincoln University Research Grant INT4052

Cataloguing cowries: a standardised strategy to record six key species of cowrie shell from the West African archaeological record

Two species of cowrie shell, Monetaria moneta (Linnaeus 1758) and Monetaria annulus (Linnaeus 1758), occur repeatedly in archaeological contexts across West Africa. Despite their archaeological and ethnographic importance, these shells remain poorly and inconsistently reported in the archaeological literature. The absence of standardised data on species composition, size and condition of cowrie assemblages, and whether and how the shells were modified, make it difficult to examine their significance in a regional and/or chronological framework. To address this, we propose a standardisation of the criteria and coding used to systematically record cowrie assemblages – in particular species, size, condition and state of modification. We aim to enable non-shell specialists within the wider archaeological community to securely identify intact or intact but modified specimens of M. annulus and M. moneta, showing how these can be distinguished from four cowries native to West Africa (specifically Luria lurida (Linnaeus 1758), Zonaria zonaria (Gmelin 1791), Zonaria sanguinolenta (Gmelin 1791) and Trona stercoraria (Linnaeus 1758)) that occur in assemblages from West African sites. We demonstrate how accurate species identification and the assessment of proportions of different sizes of shells within suitably large assemblages can provide insight into their provenance, and through this enhance our appreciation of the exchange networks within which these shells moved. We also identify five different strategies documented in the archaeological record that were used to modify cowries, detailing how these can be differentiated and classified. The aim here is to suggest a recording strategy that will enable comparisons of the use and value of cowries in West Africa and more widely