A model of spatially evolving herpesvirus epidemics causing mass mortality in Australian pilchard Sardinops sagax

In 1995 mass mortality of pilchards Sardinops sagax occurred along >5000 km of Australian coast; similar events occurred in 1998/99. This mortality was closely associated with a herpesvirus. The pilchard is an important food source for larger animals and supports commercial fisheries. Both epidemics originated in South Australian waters and spread as waves with velocities of 10 to 40 km d-1. Velocity was constant for a single wave, but varied between the epidemics and between the east- and west-bound waves in each epidemic. The pattern of mortality evolved from recurrent episodes to a single peak with distance from the origin. A 1-dimensional model of these epidemics has been developed. The host population is divided into susceptible, infected and latent, infected and infectious, and removed (recovered and dead) phases; the latent and infectious periods are of fixed duration. This model produces the mortality patterns observed locally and during the spread and evolution of the epidemic. It is consistent with evidence from pathology. The wave velocity is sensitive to diffusion coefficients, viral transmission rates and latent period. These parameters are constrained using the local and large-scale patterns of epidemic spread. The relative roles of these parameters in explaining differences between epidemics and between east- and west-bound waves within epidemics are discussed. The model predicts very high levels of infection, indicating that many surviving pilchards recovered following infection. Control appears impracticable once epidemics are initiated, but impact can be minimised by protecting juvenile stocks

Classical integrable lattice models through quantum group related formalism

We translate effectively our earlier quantum constructions to the classical language and using Yang-Baxterisation of the Faddeev-Reshetikhin-Takhtajan algebra are able to construct Lax operators and associated $r$-matrices of classical integrable models. Thus new as well as known lattice systems of different classes are generated including new types of collective integrable models and canonical models with nonstandard $r$ matrices.Comment: 7 pages; Talk presented at NEEDS'93 (Gallipoli,Italy

The Ideal Mixing Departure in Vector Meson Physics

In this work we study the departure for the ideal $\phi-\omega$ mixing angle in the frame of the Nambu-Jona-Lasinio model. We have shown that in that context, the flavour symmetry breaking is unable to produce the shifting in the mixing angle. We introduce a nonet symmetry breaking in the neutral vector sector to regulate the non-strange content of the $\phi$ meson. The phenomenon is well reproduced by our proposal.Comment: 12 pages incl. 1 figur

Geomagnetic induction studies in Scandinavia — I. Determination of the inductive response function from the magnetometer array data

Data from the Munster IMS Magnetometer Array (Kuppers et al. 1979) have been analysed in the frequency domain to derive the inductive response function, C(ω, 0), from the ratio of the vertical magnetic field to the spatial gradient of the horizontal magnetic field. The response function was best determined by statistical frequency analysis techniques after the spatial gradients had been derived by least-squares fitting of two-dimensional second-order polynomials to the observations, with the constraint imposed that the solutions be curl-free. The derived response function was found to obey two different causality requirements, and most of the inequality constraints imposed on it (Weidelt, 1972). A preliminary model, in which conductivity is a function of depth only and which explains the major details of the observed response, is presented. It has a highly resistive uppermost layer of some 104 Ωm and of the order of 30 km thick, underlain by a layer of about 125 Ωm to a depth of around 140 km, where a transition takes place to a highly conducting (3 Ωm) half space. The effect of various non-uniform sources on the observations of C(ω, k) for this 1D model is illustrated.           ARK: https://n2t.net/ark:/88439/y091007 Permalink: https://geophysicsjournal.com/article/169 &nbsp

On a type classification of lower crustal layers under Precambrian regions

Various parameters pertinent to the lower crustal layer under Precambrian regions are listed for locations where seismic, and geomagnetic or geoelectric, studies have been undertaken. The parameters define three distinct types of lower crustal layer with certain dominant characteristics: Type I – "Normal" – typical continental seismic parameters and a high electrical resistivity (103–104 Ωm); Type II – "Intermediate" – high compressional wave velocity (either fixed Vp = 7.0 km s-1 or transitional Vp = 6.7 → 7.3 km s-1) and a moderate resistivity (100–300 Ωm); Type III – "Low" – a low shear wave velocity layer (LVsL), high Poisson's ratio (> 0.30) and low electrical resistivity (10–50 Ωm). Possible conditions and rock types, existing at the P–T environment of the lower crust and which could account for the observations, are suggested. The zoning of Canada into types implies that Type II layers are shield "edge" effects, and that inability to observe what is regarded as the final stage of development of a shield region under certain shields may be due to their being too small.           ARK: https://n2t.net/ark:/88439/y052001 Permalink: https://geophysicsjournal.com/article/185 &nbsp

Geomagnetic induction studies in Scandinavia. II. Geomagnetic depth sounding, induction vectors and coast-effect

In this paper an event of very favourable structure for induction purposes, which was observed by the Scandinavian magnetometer array, is discussed and analysed in detail. The responses derived, in both the time and frequency domains, display a large coast effect at all coastal stations, both on the sea coasts and on the Gulf of Bothnia. Two relatively large inland anomalies are also delineated. The more significant of the two, the Storavan anomaly, is apparent using all the analysis techniques employed, and may be associated with a remnant of the Svionian island arc system. The less dominant anomaly, in the vicinity of Mieron, has no obvious correlation with geology or tectonic formations, and appears to be polarisation sensitive - it is only energised by east-west magnetic fields. First approximation modelling of the coast effect observed by the northwestern stations illustrated that the responses are well satisfied by the conductivity contrast between sea and land. Finally, the validity of the derived induction vectors, and the possible effects of induction for source field studies, are discussed.           ARK: https://n2t.net/ark:/88439/y095007 Permalink: https://geophysicsjournal.com/article/105 &nbsp

Direct optical excitation of a fullerene-incarcerated metal ion

The endohedral fullerene Er3N@C80 shows characteristic 1.5 micron photoluminescence at cryogenic temperatures associated with radiative relaxation from the crystal-field split Er3+ 4I13/2 manifold to the 4I15/2 manifold. Previous observations of this luminescence were carried out by photoexcitation of the fullerene cage states leading to relaxation via the ionic states. We present direct non-cage-mediated optical interaction with the erbium ion. We have used this interaction to complete a photoluminescence-excitation map of the Er3+ 4I13/2 manifold. This ability to interact directly with the states of an incarcerated ion suggests the possibility of coherently manipulating fullerene qubit states with light

Improving Bahr's invariant parameters using the WAL approach.

In the magnetotelluric technique, several methods exist to perform dimensionality analysis of the measured data using rotational invariants of the impedance tensor. Among these methods there is some dilemma on the different criteria established, which sometimes lead to non-equivalent interpretation

The influence of CO adsorption on the surface composition of cobalt/palladium alloys

AM is grateful for funding from SASOL Technology UK Ltd (PhD studentship); JG is grateful for the award of a fellowship from the Knut and Alice Wallenberg Foundation. TEJ and AGT acknowledge EPSRC funding of postdoctoral research (EP/E047580/1). The MEIS facility was funded via EPSRC grant EP/E003370/1.Segregation induced by the adsorption of gas phase species can strongly influence the composition of bimetallic surfaces and can therefore play an important role in influencing heterogeneous catalytic reactions. The addition of palladium to cobalt catalysts has been shown to promote Fischer Tropsch catalysis. We investigate the adsorption of CO onto bimetallic CoPd surfaces on Pd{111} using a combination of reflection absorption infrared spectroscopy and medium energy ion scattering. The vibrational frequency of adsorbed CO provides crucial information on the adsorption sites adopted by CO and medium energy ion scattering probes the surface composition before and after CO exposure. We show that cobalt segregation is induced by CO adsorption and rationalise these observations in terms of the strength of adsorption of CO in various surface adsorption sites.PostprintPeer reviewe

The height of Denier Tournois minting in Greece (1289–1313) according to new archaeometric data

The years 1289–1313 witnessed particularly prolific minting activities at different southern and central Greek mints on behalf of different polities. The coin issues are of great economic and political relevance, and therefore of interest to modern historians. Our understanding of these is based on traditional sources, either numismatic (types and finds), or historical. This paper aims to investigate the possibilities of adding further details to the picture through archaeometry. Specifically, tournois pennies of the three main mints of the region (Clarentza, Thebes, Naupaktos) excavated at Ancient Corinth were analysed according to two different non-destructive methods, X-ray fluorescence spectrometry (XRF) and laser-induced breakdown spectroscopy (LIBS). The resulting relative silver percentages and the fingerprints of the trace elements have supported our attempts to put the different coin types in chronological order and to add detail to the context and intent for each one of these. A vivid picture of monetary production emerges. The different issuing authorities were usually intent on maintaining a decent standard while variously trying to put pressure on rivals or to harmonise their productions with their allies. All the analysed mints were commercial in character, though they were subject to the great political changes affecting Greece in this period, the ambitions of the Angevin dynasty, the various challenges which it faced in Athens, the Peloponnese and the western Mainland, and finally the destructive arrival of the Catalans. In times of need, specifically military, these same mints could therefore rely on further bullion which reached them through internal or external political channels