Integrated geophysical surveys to assess the structural conditions of a karstic cave of archaeological importance

An integrated geophysical survey using both the electrical resistivity tomography (ERT) and ground-penetrating radar (GPR) methods was undertaken over a cave of great archaeological interest in southern Italy. The survey was performed to assess the stability of the carbonate rock roof of the cave. A geophysical survey was preferred to boreholes and geotechnical tests, in order to avoid the risk of mass movements. The interpretation of integrated data from ERT and GPR resulted in an evaluation of some of the electromagnetic (EM) characteristics (such as the EM wave velocity) and the detection of discontinuities (fractures) in the carbonate rock. It is well known that rock fractures constitute a serious problem in cave maintenance, and progressive cracking within the bed rock is considered to be one of the main causes of collapse. An analysis of the back-scattered energy was also required for the GPR data interpretation. Cracks within the bedrock were detected to a depth of about 2 m by using GPR, which allowed for the identification of the loosened zone around the cave

Programming and Audits Committee Meeting Agenda 10/26/2011

Student Government Senate Committee on Programming and Audits meeting agenda for 10/26/201

Ground Penetrating Radar (GPR): an application for evaluating the state of maintenance of the building coating

Ground Penetrating Radar (GPR) is a non-destructive methodology. For the localisation of buried structures, it uses short time duration electromagnetic (EM) pulses lasting from about 1 ns to about 30 ns. Therefore, GPR is characterised by a wide frequency band ranging from 10 MHz to some GHz, and is useful in the localisation of EM discontinuities in the subsurface with high resolution. This paper describes an application of GPR to evaluate the state of maintenance of some travertine panels attached to the inside walls of a building housing the Bank of Naples in Campobasso and in danger of falling because of the numerous voids present between the wall and the panels. The aim of the survey was to assess whether the GPR technique could be used to detect the voids behind the travertine panels. The study was made to assist the design of the restoration works of the travertine covering. Because of the very narrow thickness of both the travertine plates and the voids, special care was needed in the acquisition and processing steps. The measurements were performed on two panels: one purposely put on to the laboratory wall with a known position of the voids; the other one selected from among the panels to be restored. Although pushed to the limit of the resolution achievable by the available antenna, the study has given quite good results

Reorganizing territorial healthcare to avoid inappropriate ED visits: does the spread of Community Health Centres make Walk-in-Clinics redundant?

BACKGROUND: Community care has recently been restructured with the development of Community Health Centres (CHCs), forcing a general rethink on the survival of previous organizational solutions adopted to reduce inappropriate ED access, for example Walk-in-Clinics (WiCs). METHODS: We focus on the Italian Emilia-Romagna Region that has made huge investments in CHC development, whilst failing to proceed at a uniform rate from area to area. Estimating panel count data models for the period 2015-2018, we pursue two goals. First we test the existence of a "CHC effect", choosing five urban cities with different degree of development of the CHC model and assessing whether, all else being equal, patients treated by GPs who have their premises inside the CHC show a lower need to seek inappropriate care (Aim 1). Second, we focus our attention on Walk-in-Clinics, investigating the long-established WiC in the city of Parma that currently coexists with three CHCs recently established in the same catchment area. In this case we try to assess whether, and to what extent, the progressive development of the CHCs in the city of Parma has been affecting the dynamics of WiC access (Aim 2). RESULTS: As regards Aim 1, we show that CHCs reduce the probability of inappropriate patient access to emergency care. As regards Aim 2, in the city of Parma patients whose GP belongs to the CHC are less likely to visit the WiC on a workday, with no significant change during the weekend when CHCs are closed, questioning the need to maintain them both in the same area when the CHC model is fully implemented. CONCLUSIONS: Our results confirm the hypothesis that expanding access to primary care settings diminishes inappropriate ED use. In addition, our findings suggest that where CHCs and WiCs coexist in the same area, it may be advisable to implement strategies that bring WiC activities into step with CHC-based general primary care reforms to avoid duplication

Integrated geophysical and geological investigations applied to sedimentary rock mass characterization

The Salento Peninsula (south-eastern Italy) is characterized by sedimentary rocks. The carbonatic nature of the rocks means they are affected by karst phenomena, forming such features as sinkholes, collapsed dolines and caverns, as a result of chemical leaching of carbonates by percolating water. The instability of these phenomena often produces land subsidence problems. The importance of these events is increasing due to growing urbanization, numerous quarries affecting both the subsoil and the surface, and an important coastline characterized by cliffs. This paper focuses on geological and geophysical methods for the characterization of soft sedimentary rock, and presents the results of a study carried out in an urban area of Salento. Taking the Q system derived by Barton (2002) as the starting point for the rock mass classification, a new approach and a modification of the Barton method are proposed. The new equation proposed for the classification of sedimentary rock mass (Qsrm) takes account of the permeability of the rock masses, the geometry of the exposed rock face and their types (for example, quarry face, coastal cliff or cavity), the nature of the lithotypes that constitute the exposed sequence, and their structure and texture. This study revises the correlation between Vp and Q derived by Barton (2002), deriving a new empirical equation correlating P-wave velocities and Qsrm values in soft sedimentary rock. We also present a case history in which stratigraphical surveys, Electrical Resistivity Tomography (ERT), and seismic surveys were applied to in situ investigations of subsidence phenomena in an urban area to estimate rock mass quality. Our work shows that in the analysis of ground safety it is important to establish the rock mass quality of the subsurface structures; geophysical exploration can thus play a key role in the assessment of subsidence risk

Application of 3D visualization techniques in the analysis of GPR data for archaeology

In this work, some results of a GPR survey carried out in a 10000 m2 large archaeological site, located in Lecce (Italy) near to a necropolis dating from the Messapian to the Roman imperial age, are reported. After a preliminary survey, performed on the entire area along parallel 1 m spaced profiles using a 200 MHz and a 500 MHz antenna in single-fold continuous mode, some smaller areas were selected, where the survey was repeated decreasing the profile spacing down to 0.50 m for the lower frequency antenna and to 0.25 m for the higher one. For two selected zones (D and B) the processed data were visualized in 3D space not only by the standard time slice technique, but also by two recently proposed approaches, namely by iso-amplitude surfaces of the complex trace amplitude and by 3D projection of energy and envelope stacks. The immediacy in revealing the spatial positioning of highly reflecting bodies, such as the anomaly interpreted as an old refilled cistern in zone D, makes 3D visualization techniques very attractive in archaeological applications of GPR. Their sensitivity to the signal/noise ratio is, on the other hand, highlighted by the quite poor performance in zone B, where the only reliable result provided by all the techniques was the soil/bedrock reflection, whereas none of them could effectively enhance the visibility of weak dipping reflections noted on 2D sections and probably related to fractures or bedding planes in the calcarenitic basement. The performance of the various techniques in these two different situations allowed insights into their main advantages and drawbacks to be gained

Towards urban archaeo-geophysics in Peru. The case study of Plaza de Armas in Cusco

One of the most complex challenges of heritage sciences is the identification and protection of buried archaeological heritage in urban areas and the need to manage, maintain and inspect underground services. Archaeology and geophysics, used in an integrated way, provide an important contribution to open new perspectives in understanding both the history of cities and in helping the decision makers in planning and governing the urban development and management. The problems of identification and interpretation of geophysical features in urban subsoil make it necessary to develop ad hoc procedures to be implemented and validated in significant case studies. This paper deals with the results of an interdisciplinary project in Cusco (Peru), the capital of Inca Empire, where the georadar method was applied for the first time in the main square. The georadar method was successfully employed based on knowledge of the historical evolution of Cusco and the availability of archaeological records provided by some excavations nearby the study area. Starting from a model for the electromagnetic wave reflection from archaeological structures and pipes, georadar results were interpreted by means of comparative morphological analysis of high amplitude values observed from time slices with reflectors visualized in the radargrams

TDR-based water content estimation on globigerina limestone through permittivity measurements

Most monuments and historical buildings in the Maltese Islands are made of the local Globigerina Limestone (GL). This type of stone, however, is very delicate and prone to degradation caused by the environmental conditions of the islands. Hence, for the preservation of the Cultural Heritage monuments, it is necessary to promptly assess the health status of these structures and, in particular, their water content (which represents one of the major causes of degradation). Starting from these considerations, in this work, a time domain reflectometry (TDR)-based method for estimating water content of GL is presented. More specifically, the proposed method relies on estimating the water content value of the GL structure from TDR-based dielectric permittivity measurements. To verify the suitability of this system, experimental tests were carried out on a GL sample. The results anticipate the strong potential of the proposed method for practical applications in the Cultural Heritage diagnostics

Application of 3D visualization techniques in the analysis of GPR data for archaeology

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