The curatorial consequences of being moved, moveable or portable: the case of carved stones

It matters whether a carved stone is moved, moveable or portable. This influences perceptions of significance and of form and nature – is it a monument or an artefact? This duality may in turn affect understanding and appreciation of the resource. It has implications for how and if carved stones can be legally protected, who owns them, where and how they are administered, and by whom. The complexities of the legislation mean that all too often this is also a grey area. This paper explores these curatorial issues and their impact

Three-dimensional cometary dust coma modelling in the collisionless regime: strengths and weaknesses

Inverse coma and tail modelling of comets based on the method developed by Finson & Probstein is commonly used to analyse cometary coma images. Models of this type often contain a large number of assumptions that may not be constrained unless wide temporal or spectral coverage is available and the comets are bright and at relatively small geocentric distance. They are used to predict physical parameters, such as the mass distribution of the dust, but rarely give assessments of the accuracy of the estimate. A three-dimensional cometary dust coma model in the collisionless regime has been developed to allow the effectiveness of such models to constrain dust coma properties to be tested. The model is capable of simulating the coma morphology for the following input parameters: the comet nucleus shape, size, rotation, emission function (including active fraction and jets), grain velocity distribution (and dispersion), size distribution, dust production rate, grain material and light scattering from the cometary dust. Characterization of the model demonstrates that the mass distribution cannot be well constrained as is often assumed; the cumulative mass distribution index ? can only be constrained to within ±0.15. The model is highly sensitive to the input grain terminal velocity distribution so model input can be tested with a large degree of confidence. Complex secondary parameters such as jets, rotation and grain composition all have an effect on the structure of the coma in similar ways, so unique solutions for these parameters cannot be derived from a single optical image alone. Multiple images at a variety of geometries close in time can help constrain these effects. The model has been applied to photometric observations of comets 126P/IRAS and 46P/Wirtanen to constrain a number of physical properties including the dust production rate and mass distribution index. The derived dust production rate (Qdust) for 46P/Wirtanen was 3+7/1.5 kg s1 at a pre-perihelion heliocentric distance of 1.8 au, and for P/IRAS was 50+100/20 kg s1 at a pre-perihelion heliocentric distance of 1.7 au; both comets exhibited a mass distribution index ? = 0.8 ± 0.15

A Study of the Biology of \u3ci\u3eRhopalosiphum Padi\u3c/i\u3e (Homoptera: Aphididae) in Winter Wheat in Northwestern Indiana

Periodic collections of the bird cherry-oat aphid, Rhopalosiphum padi, during two years revealed small populations on winter wheat in Lafayette, Indiana. The greatest numbers were found on volunteer wheat plants before planting. In the autumn, aphids were detected on one-shoot plants by mid-October and also early March. The populations remained small until mid-June. We conclude that the aphid feeding did not significantly affect the plants, but helped spread barley yellow dwarf virus

Organic Farming Development and Agricultural Institutions in Europe: A Study of Six Countries

Cooperation between general agricultural institutions and the organisation of the organic farming sector are key factors for the development of organic farming. This study analyses the relationships of organic farming organisations with other farmers' organisations, agencies of agricultural policy and food market firms in six European countries. On this basis it identifies a path for successful development of organic farming which is adaptable to the special conditions of all European countries. This book presents the most systematic and in-depth comparison of the dynamics of organic farming development to date, providing concrete suggestions for a line of action for everyone with an interest in developing organic farming

Self-discharge in bimetallic cells containing alkali metal

Theoretical analysis of thermally regenerative bimetallic cells with alkali metal anodes shows a relation between the current drawn and the rate of discharge under open-circuit conditions. The self-discharge rate of the cell is due to the dissolution and ionization of alkali metal atoms in the fused-salt electrolyt

Prompt energization of relativistic and highly relativistic electrons during a substorm interval: Van Allen Probes observations

Abstract On 17 March 2013, a large magnetic storm significantly depleted the multi-MeV radiation belt. We present multi-instrument observations from the Van Allen Probes spacecraft Radiation Belt Storm Probe A and Radiation Belt Storm Probe B at ~6 Re in the midnight sector magnetosphere and from ground-based ionospheric sensors during a substorm dipolarization followed by rapid reenergization of multi-MeV electrons. A 50% increase in magnetic field magnitude occurred simultaneously with dramatic increases in 100 keV electron fluxes and a 100 times increase in VLF wave intensity. The 100 keV electrons and intense VLF waves provide a seed population and energy source for subsequent radiation belt enhancements. Highly relativistic (\u3e2 MeV) electron fluxes increased immediately at L* ~ 4.5 and 4.5 MeV flux increased \u3e90 times at L* = 4 over 5 h. Although plasmasphere expansion brings the enhanced radiation belt multi-MeV fluxes inside the plasmasphere several hours postsubstorm, we localize their prompt reenergization during the event to regions outside the plasmasphere. Key Points Substorm dynamics are important for highly relativistic electron energization Cold plasma preconditioning is significant for rapid relativistic energization Relativistic / highly relativistic electron energization can occur in \u3c 5 hrs

Universality of collapsing two-dimensional self-avoiding trails

Results of a numerically exact transfer matrix calculation for the model of Interacting Self-Avoiding Trails are presented. The results lead to the conclusion that, at the collapse transition, Self-Avoiding Trails are in the same universality class as the O(n=0) model of Blote and Nienhuis (or vertex-interacting self-avoiding walk), which has thermal exponent $\nu=12/23$, contrary to previous conjectures.Comment: Final version, accepted for publication in Journal of Physics A; 9 pages; 3 figure

Link and subgraph likelihoods in random undirected networks with fixed and partially fixed degree sequence

The simplest null models for networks, used to distinguish significant features of a particular network from {\it a priori} expected features, are random ensembles with the degree sequence fixed by the specific network of interest. These "fixed degree sequence" (FDS) ensembles are, however, famously resistant to analytic attack. In this paper we introduce ensembles with partially-fixed degree sequences (PFDS) and compare analytic results obtained for them with Monte Carlo results for the FDS ensemble. These results include link likelihoods, subgraph likelihoods, and degree correlations. We find that local structural features in the FDS ensemble can be reasonably well estimated by simultaneously fixing only the degrees of few nodes, in addition to the total number of nodes and links. As test cases we use a food web, two protein interaction networks (\textit{E. coli, S. cerevisiae}), the internet on the autonomous system (AS) level, and the World Wide Web. Fixing just the degrees of two nodes gives the mean neighbor degree as a function of node degree, $_k$, in agreement with results explicitly obtained from rewiring. For power law degree distributions, we derive the disassortativity analytically. In the PFDS ensemble the partition function can be expanded diagrammatically. We obtain an explicit expression for the link likelihood to lowest order, which reduces in the limit of large, sparse undirected networks with $L$ links and with $k_{\rm max} \ll L$ to the simple formula $P(k,k') = kk'/(2L + kk')$. In a similar limit, the probability for three nodes to be linked into a triangle reduces to the factorized expression $P_{\Delta}(k_1,k_2,k_3) = P(k_1,k_2)P(k_1,k_3)P(k_2,k_3)$.Comment: 17 pages, includes 11 figures; first revision: shortened to 14 pages (7 figures), added discussion of subgraph counts, deleted discussion of directed network

Network growth models and genetic regulatory networks

We study a class of growth algorithms for directed graphs that are candidate models for the evolution of genetic regulatory networks. The algorithms involve partial duplication of nodes and their links, together with innovation of new links, allowing for the possibility that input and output links from a newly created node may have different probabilities of survival. We find some counterintuitive trends as parameters are varied, including the broadening of indegree distribution when the probability for retaining input links is decreased. We also find that both the scaling of transcription factors with genome size and the measured degree distributions for genes in yeast can be reproduced by the growth algorithm if and only if a special seed is used to initiate the process.Comment: 8 pages with 7 eps figures; uses revtex4. Added references, cleaner figure