Applications of MCMC methods on function spaces

In the course of this thesis, several different applications of data assimilation will be looked at. In each case, a rigorous mathematical framework will be constructed, in a Bayesian context, to enable the use of various types of data to infer on various infinite dimensional parameters of the system that has been observed. After careful consideration of the forward problem, well-defined posterior distributions on function space are constructed. Using MCMC methods which are defined on these function spaces themselves, we can construct Markov chains whose invariant measures are the posterior of interest. From this point, we can implement these methods on a computer, having finally discretised the problem. The philosophy that we adhere to throughout, is the idea that numerical methods formulated on function space are robust under discretisation, and do not suffer from the curse of dimensionality typically suffered by sampling methods formulated after disretisation. The first few chapters (after the introductory chapter) will focus on various aspects of data assimilation of observations of Stokes ow dynamics. Chapter 2 will focus on Eulerian data where direct observations of the velocity of the fluid at various points in time and space will be made. Chapter 3 will concentrate on data assimilation of indirect observations of the field, in the form of the positions of passive tracers in the flow. In these two chapters we will assume that the forcing of the system is known and that we are merely trying to recover the initial condition of the flow field. In chapter 4 we will consider both Eulerian and Lagrangian data assimilation, with the added complexity of trying to use the data to not only infer on the initial condition but also on the space-time dependant forcing of the system. In chapter 5 we will try to show how these smoothing methods could be adapted into a filtering algorithm, and a simple example will be presented. In the final chapter, 6, this Bayesian framework on function space will be applied to a shape matching problem with applications in the biomedical sciences.EThOS - Electronic Theses Online ServiceEngineering and Physical Sciences Research Council (EPSRC)GBUnited Kingdo

Small Heat Shock Protein αA-Crystallin Prevents Photoreceptor Degeneration in Experimental Autoimmune Uveitis

The small heat shock protein, αA-crystallin null (αA−/−) mice are known to be more prone to retinal degeneration than the wild type mice in Experimental Autoimmune Uveoretinitis (EAU). In this report we demonstrate that intravenous administration of αA preserves retinal architecture and prevents photoreceptor damage in EAU. Interestingly, only αA and not αB-crystallin (αB), a closely related small heat shock protein works, pointing to molecular specificity in the observed retinal protection. The possible involvement of αA in retinal protection through immune modulation is corroborated by adaptive transfer experiments, (employing αA−/− and wild type mice with EAU as donors and Rag2−/− as the recipient mice), which indicate that αA protects against the autoimmune challenge by modulating the systemic B and T cell immunity. We show that αA administration causes marked reduction in Th1 cytokines (TNF-α, IL-12 and IFN-γ), both in the retina and in the spleen; notably, IL-17 was only reduced in the retina suggesting local intervention. Importantly, expression of Toll-like receptors and their associated adaptors is also inhibited suggesting that αA protection, against photoreceptor loss in EAU, is associated with systemic suppression of both the adaptive and innate immune responses

New mediterranean biodiversity records (November, 2016)

This Collective Article presents information on 26 taxa belonging to 8 Phyla and extending from the western Mediterranean to the Levantine Sea. The new records were found in 9 countries as follows: Spain: first record for the Mediterranean of the crab Cancer bellianus; Algeria: further records of the alien fish Lagocephalus sceleratus in western Algerian waters; Italy: first report on the presence and establishment of the ctenophore Mnemiopsis leidyi in Lessina and Varano Lagoons (W. Adriatic) and of Penaeus aztecus in Corigliano Gulf (Italian Ionian). Moreover, the extension of the distribution range of the polychaete Branchiomma bairdi to W. Sicily as well as that of the crab Ocypode cursor and the bryozoan Catenicella paradoxa to E. Sicily are cited. Slovenia: the record of the rare saccoglossan gastropod Placida cremoniana from Piran (Gulf of Trieste) is the first for the Adriatic; Greece: the native sea slug Eubranchus farrani is the first from the Eastern Mediterranean; many sightings of the bamboo corals Isididae distributed along all the E. Ionian Sea and the establishment of P. aztecus in all Greek waters are also reported for first time; the westernmost extension of the alien urchin Diadema setosum in Cretan waters is cited and new sightings of the alien species Goniobranchus annulatus and Pterois miles are presented. Turkey: the alien fish Champsodon capensis is reported for first time from the Aegean Sea and the native acari Agauopsis microrhyncha from the Levantine Sea; a new observation of the alien crab Atergatis roseus in Güllük Bay-Aegean is also mentioned; Cyprus: first records of the alien urchin D. setosum and Lobotes surinamensis in Cypriot waters; Lebanon: several sightings of Monachus monachus from Lebanese waters indicate a potential better status for the species in the area; Egypt: first records of the alien crab Dorippe quadridens and the alien gastropods Nerita sanguinolenta and Conomurex persicus from the Mediterranean Egyptian waters; extension of the distribution range of Diodora funiculata and Diodora rueppellii and a second record of the alien Fulvia fragilis in the same area

Eleven years monitoring of Lesina lagoon (South Italy) using a biotic index (Λ)

1 - The scope of our work was to assess the ecological status of Lesina lagoon on the South Adriatic coast of Italy according to the biological priorities expressed by the directives of the government, priorities which can be summed up in the key words of bionomics, biomass and biodiversity. 2 - Our method was based on the characteristics of the sessile benthic macrofauna considered to be indicative of environmental status. We developed a biotic index (Λ) that grades from 1 to 10 the rising quality of the environment. The data required for applying the index, i.e. spatial distribution (Zonation), biomass (g ww/m2) and number of species of the benthic macrofauna, were obtained from samples of sediment taken at systematically distributed stations over the entire surface of the lagoon. Samples were taken in spring and again in autumn. 3 - Our first assessment in Jan. 1993 gave 8.48, a high value. No samples were taken in 1994 but quality probably remained high because in Nov. 1995 the index gave 7.86. In 1996 quality must have begun to decline because although we took no sample in that year, in May 1997 the index was 6.14, which is very low for spring, when quality is normally high. The situation did not improve until August 1998 when the index rose to 7.59. From then on till our last assessment in Oct. 2003 the environmental quality of Lesina was at a stable high, the index registering values above 7.00 with a peak of 8.15 in Aug. 1999. 4 - The index values that we registered closely coincided with the opinion on the state of the environment given by experienced fishermen whose livelihood depends on the quality of the lagoon

Zooplankton composition in the lake Varano (Adriatic Sea coast, Italy)

The zooplankton composition of Lake Varano has been studied from June 2007 to May 2008 considering three sampling stations (western, central, eastern). A total of 55 zooplankton categories were recognised, with medusae Aurelia aurita as the main macroscopic species; 43 of them occurred in less than 50% of the 71 samples collected, highlighting the seasonal aspect of the community. The remaining 12 categories, present in more than 50% of samples, were numerically dominated by the copepod ‘Non Indigenous Species’ Acartia tonsa (reported here for the first time in the lake), which occurred throughout the year. Maximal abundance of zooplankton was recorded in the eastern sampling station, while the lowest values were recorded in the central one. The statistical analysis of data allowed us to establish a not sharp separation of the three sampling stations, apart from isolated dates. The present zooplankton assemblage showed that about 40% of its components differed from those recorded in a study of 18 years before. This last comparison is not easily referable to the ongoing climate warming (the dominant species are of cold temperate origin) and analysis of uninterrupted time series could be useful to understand the underlying reasons

A probabilistic approach to set operating reserve margins in a multi-area electric power system

In a deregulated electric system, ISO is always responsible for system reliability and security, ensuring an adequate level of operating reserve, to be activated automatically (primary reserve for frequency control and secondary reserve for load-frequency control) or manually (tertiary spinning and non-spinning reserve). After the intervention of load-frequency regulation, the regulating band must be restored in order to guarantee the assigned availability to the system; this is obtained by using the tertiary reserve margins for balancing operations. The evaluation of the operating reserve in a multi-area system is generally carried out on a deterministic basis, using the so called “first contingency security criterion”. As an alternative, this paper focuses on a simulation method, based on a probabilistic approach using a Sequential Montecarlo technique, and a case study relevant to a three-area generating system is shown

First record of sinanodonta woodiana (Lea, 1834) in an artificial reservoir in the molise region, Southeast Italy

The occurrence of the Chinese pond mussel Sinanodonta woodiana is reported for the first time in the Molise region (Southeast Italy). Details of the mussel’s invasion history in Italy are also given. A total of 24 S. woodiana specimens were collected after a long drought period in October 2017 from an emerged beach on the southwest side of the Guardialfiera artificial lake and their main morphometric features were quantified. No young individuals were found, only large adults, whose survival could ensure population subsistence in more suitable environmental conditions. The present study provides evidence of a massive die-off affecting invasive bivalves during an extreme climatic event, producing decaying biomass with negative impacts on the water quality of the lake. Further investigations of the population dynamics of this species and the environmental quality of the water body are needed to develop an appropriate management plan in relation to the ecosystem services it delivers

Aricidea fragilis (Annelida: Paraonidae) in the Mediterranean Sea: overlooked native or alien species?

The paraonid polychaete Aricidea fragilis Webster, 1879, a typically west-Atlantic species, is reported from the Mediterranean Sea on the basis of several individuals, from the Adriatic and Tyrrhenian Sea. Its differences with the other Mediterranean Paraonidae, and in particular with the morphologically close Aricidea suecica meridionalis Laubier & Ramos, 1974, are briefly discussed. The possible status of A. fragilis as an alien species in European waters is analysed. The scarcity of historical records, the relatively restricted distribution, and the population dynamics observed in European waters strongly support the hypothesis of an introduction, despite the wide temporal interval between the first record of the species in the 1930s and the currently ongoing range expansion and population explosion. Here we precautionarily suggest considering A. fragilis a cryptogenic species