3-D GPR survey with a modular system: reducing positioning inaccuracies and linear noise

Recently, the use of ground-penetrating radar (GPR) arrays with a large number of antenna elements in a fixed configuration has become more common. The investment needed for these systems is significant. Although gradually expandable modular systems, consisting of antennas which can be used independently, do not match the fast acquisition of detailed datasets by means of multi-channel arrays, they can help finding a compromise between increased acquisition speed and (limited) resources. In modular systems, the separation between transmitter-receiver pairs is often larger than the sampling distance prescribed by the Nyquist theorem. As a consequence, additional profiles have to be recorded in between, which requires a high positioning precision. As a completely identical response for the different antennas in an array is difficult to achieve, stripes can occur in the horizontal slices, especially when ringing occurs. This complicates the interpretation of features in the direction of the survey lines. In this paper, a three-dimensional frequency-wavenumber filter is proposed, consisting in a combination of a circular filter and a fan filter. The application of this filter to GPR data collected at the Roman town Mariana (Corsica, France) showed a reduction of the stripe patterns, allowing a more reliable characterization of subtle archaeological structures

Enterotoxigenic Escherichia coli induce pro-inflammatory responses in porcine intestinal epithelial cells

F4+ enterotoxigenic Escherichia coli (ETEC) cause severe diarrhoea in both neonatal and weaning piglets, resulting in morbidity and mortality. F4 fimbriae are a key virulence factor involved in the attachment of F4+ ETEC to the intestinal epithelium. Intestinal epithelial cells (IEC) are recently being recognized as important regulators of the intestinal immune system through the secretion of cytokines, however, data on how F4+ ETEC affect this cytokine secretion are scarce. By using ETEC strains expressing either polymeric, monomeric or F4 fimbriae with a reduced polymeric stability, we demonstrated that polymeric fimbriae are essential for the adhesion of ETEC to porcine IEC as well as for the secretion of IL-6 and IL-8 by ETEC-stimulated intestinal epithelial cells. Remarkably, this cytokine secretion was not abrogated following stimulation with an F4-negative strain. As this ETEC strain expresses flagellin, TLR5 mediated signalling could be involved. Indeed, porcine IEC express TLR5 and purified flagellin induced IL-6 and IL-8 secretion, indicating that, as for other pathogens, flagellin seems to be the dominant virulence factor involved in the induction of proinflammatory responses in IEC upon ETEC infection. These results indicate a potential mucosal adjuvant capacity of ETEC-derived flagellin and may improve rational vaccine design against F4+ ETEC infections

The possibility of positive selection for both F18(+) Escherichia coli and stress resistant pigs opens new perspectives for pig breeding

International audienc

Ground-penetrating radar survey at Falerii Novi : a new approach to the study of Roman cities

Our understanding of Roman urbanism relies on evidence from a few extensively investigated sites, such as Pompeii and Ostia, which are unrepresentative of the full variety of Roman towns. This article presents the results of the first high-resolution GPR survey of a complete Roman town-Falerii Novi, in Lazio, Italy. The authors review the methods deployed and provide an overview of the results, including discussion of a case-study area within the town. They demonstrate how this type of survey has the potential to revolutionise archaeological studies of urban sites, while also challenging current methods of analysing and publishing large-scale GPR datasets

The Impact of High Resolution Ground-Penetrating Radar Survey on Understanding Roman Towns: case studies from Falerii Novi and Interamna Lirenas (Lazio, Italy)

Abstract—In three field seasons, the Roman towns Falerii Novi and Interamna Lirenas (Lazio, Italy) were surveyed using ground-penetrating radar (GPR). The aim was to take maximum advantage of the high resolution capability of the GPR technique. Beside the choice of the antenna frequency, unaliased data recording is important when undertaking a fullresolution GPR survey. In this project, the use of a GPR array allowed a high sample density (~0.05 m in in-line direction, and ~0.06 m in cross-line direction). The accuracy and precision of the positioning by means of an RTK GNSS and a robotic total station nearly fulfilled the requirement that the accuracy and precision should be better than half the required sample density (in this case ~0.04 m). The data were 3D migrated, which improves the lateral resolution. The results of the survey contributed to the understanding of the investigated Roman towns and their early development. For example, private houses, revealed in detail, confirm the existence of a regular pattern of land allotment

Ground-penetrating radar survey at Falerii Novi: a new approach to the study of Roman cities

Our understanding of Roman urbanism relies on evidence from a few extensively investigated sites, such as Pompeii and Ostia, which are unrepresentative of the full variety of Roman towns. This article presents the results of the first high-resolution GPR survey of a complete Roman town—Falerii Novi, in Lazio, Italy. The authors review the methods deployed and provide an overview of the results, including discussion of a case-study area within the town. They demonstrate how this type of survey has the potential to revolutionise archaeological studies of urban sites, while also challenging current methods of analysing and publishing large-scale GPR datasets.AHRC grant AH/M006522/