A study of stability analysis of pyroclastic covers based on electrical resistivity measurements

Usually, the degree of stability of a slope is quantified by the Factor of Safety whose values depend on physical and mechanical soil properties analyzed on samples of much reduced sizes or referring to very small soil volumes around porous probes. To overcome the limit of punctual information, we propose a semi-empirical approach based on the use of geophysical methods and the employment of a geophysical Factor of Safety recently introduced by the authors in terms of local resistivities and slope angles. In this paper, we show an application of our proposal on a test area of about 2000 m2 on Sarno Mountains (Campania Region - Southern Italy), where shallow landslides involving pyroclastic soils periodically occur triggered by critical rainfall events. Starting from two resistivity tomography surveys performed on the test area in autumn and spring, we obtained maps of the geophysical Factor of Safety at different depths for the two seasons. We also estimated the values of the Factor of Safety by using the infinite slope model in the dry and saturated scenario. A comparison between the values of the geophysical and geotechnical Factor of Safety shows advantages and disadvantages of our approach.Comment: 16 pages, 5 figure

New Insights In Veterinary Forensic Medicine and Pathology

Over the last years, the knowledge on the veterinary forensic medicine and pathology has experienced a rapid increase as evidenced by number of peer- reviewed publications, textbooks and inclusion of the topic in many veterinary medical conferences. However, most of the information in veterinary forensic medicine is still acquired by human forensic literature. This lack of information is currently considered a serious problem in veterinary forensic medicine. Indeed, although it is undeniably true that the mechanisms of forensic injuries as well as the post-mortem cadaveric changes are similar between humans and animals, the different morphology, weight and tissue resistance of animals compared to human anatomy and other species-specific factors make the information validated in human forensic medicine not always applicable in the veterinary forensic field. In addition, in human forensic medicine, the macroscopic examination associated with the histological analysis is often not sufficient to determine the victim’s cause and manner of death “beyond all reasonable doubt". Therefore, in human medicine, a range of ancillary tests have been proposed to confirm specific causes of death such as the diatom test for the diagnosis of drowning or a seminal fluid test for the diagnosis of Animal Sexual Abuse (ASA). Although the application of some of these tests has been sporadically described in veterinary medicine, their use in veterinary forensics practice requires additional rigorous validation studies. Therefore, the purpose of this thesis work is to summarize the studies carried out throughout the PhD scholarship, which were based on development of new methodological approaches in veterinary forensic medicine and pathology. Attention was paid to these sub-fields of the veterinary forensic medicine: 1) Forensic photography 2) Forensic traumatology 3) Post mortem interval 4) Diagnosis of drowning and 5) Forensic microbiology. As regard the forensic photography, we assessed the suitability of “Google Glass device” in veterinary forensic photographic documentation; furthermore, in forensic traumatology field, we reported the first case of cardiac rupture following non-penetrating chest trauma (NCT) in a cat. Moreover, we presented unusual cases of cardiac rupture with NCT in two dogs. As regard the post mortem interval, we investigated the correlation between time since death and post mortem muscle proteins degradation in dog. In addition, as regard the diagnosis of drowning, we evaluated: 1) the macroscopic and microscopic findings in drowned animals and the contribution of necropsy and histological examination to determine the cause of death in drowning cases in veterinary forensic pathology 2) the differences in the number and location of diatoms between animals who died in drowning and nondrowning conditions and 3) the correlation between the time of permanence in water and the number and location of diatoms in animals dead for causes other than drowning and subsequently used for experimental drowning in standard conditions. Finally, in forensic microbiology field, we assessed the contribution of post-mortem microbiology in establishing a cause of death in young dogs who died of sudden and unexpected death. The results of my thesis showed that Google Glasses were usable in the veterinary forensic pathology of pet animals allowing a reduction in the mean execution time of necropsy and the acquisition of images useful for forensic documentation purposes. Furthermore, as regard the post-mortem modification of the muscles, we observed a time depend post-mortem degradation of the muscle proteins such as desmin and dystrophin. In addition, as regard the diagnosis of drowning, we reported a statistically higher diatom number in the tissues of drowned animals than in the tissue of nondrowned animals and experimentally drowned cadavers. In contrast, similar macroscopic and histological injuries were observed in both nondrowned and drowned animals. Finally, as regard the forensic microbiology, we observed a high frequency of viruses and bacteria detected in cases of animals who died of sudden and unexpected death such as the following: Canine Parvovirus type 2, Clostrifium Perfrigens and Canine Distemper Virus. Together, these findings will provide useful tools to increase the knowledge in veterinary forensic medicine by reducing the acquisition of information from the human medical literature which, although very complete, does not provide information that are perfectly applicable to the species of veterinary interes

A cellular automaton for the factor of safety field in landslides modeling

Landslide inventories show that the statistical distribution of the area of recorded events is well described by a power law over a range of decades. To understand these distributions, we consider a cellular automaton to model a time and position dependent factor of safety. The model is able to reproduce the complex structure of landslide distribution, as experimentally reported. In particular, we investigate the role of the rate of change of the system dynamical variables, induced by an external drive, on landslide modeling and its implications on hazard assessment. As the rate is increased, the model has a crossover from a critical regime with power-laws to non power-law behaviors. We suggest that the detection of patterns of correlated domains in monitored regions can be crucial to identify the response of the system to perturbations, i.e., for hazard assessment.Comment: 4 pages, 3 figure

Short-Circuit Protection Schemes for LVDC Microgrids Based on the Combination of Hybrid Circuit Breakers and Mechanical Breakers

In recent years, low-voltage direct current (LVDC) microgrids are becoming more attractive because they represent a solution to integrate renewable sources, storage, and electronic loads bringing some advantages in comparison with traditional AC grids. However, the protection of such a network involves many challenges, especially in the case of LVDC microgrids with more than one feeder and multiple energy sources. Indeed, the traditional protection breakers used for an AC grid cannot isolate the faults and protect the components of a DC grid, while the use of solid-state circuit breakers increases energy losses. This paper deals with the analysis and design of the protection schemes for LVDC microgrids through the combination of mechanical circuit breakers and hybrid circuit breakers. This solution has the advantage of energy loss reduction but introduces further issues due to the slow transition times of the mechanical circuit breakers. Thus, a completely decentralized control system capable of overcoming the fast fault-clearing time, cost-effectiveness, and selectivity issues is designed to protect from pole-to-pole faults. The proposed control strategy is compared with a centralized protection scheme available in the literature through numerical simulation. The two algorithms show similar performances, with a mean voltage dip duration of less than 30 ms and a maximum voltage dip duration of about 100 ms in the most severe fault condition, but the proposed solution is more reliable and flexible since it does not depend on the communication system

Estimating soil suction from electrical resistivity

Abstract. Soil suction and resistivity strongly depend on the degree of soil saturation and, therefore, both are used for estimating water content variations. The main difference between them is that soil suction is measured using tensiometers, which give point information, while resistivity is obtained by tomography surveys, which provide distributions of resistivity values in large volumes, although with less accuracy. In this paper, we have related soil suction to electrical resistivity with the aim of obtaining information about soil suction changes in large volumes, and not only for small areas around soil suction probes. We derived analytical relationships between soil matric suction and electrical resistivity by combining the empirical laws of van Genuchten and Archie. The obtained relationships were used to evaluate maps of soil suction values in different ashy layers originating in the explosive activity of the Mt Somma-Vesuvius volcano (southern Italy). Our findings provided a further example of the high potential of geophysical methods in contributing to more effective monitoring of soil stress conditions; this is of primary importance in areas where rainfall-induced landslides occur periodically

Revealing the spatiotemporal complexity of the magnitude distribution and b-value during an earthquake sequence

The Magnitude–Frequency-Distribution (MFD) of earthquakes is typically modeled with the (tapered) Gutenberg–Richter relation. The main parameter of this relation, the b-value, controls the relative rate of small and large earthquakes. Resolving spatiotemporal variations of the b-value is critical to understanding the earthquake occurrence process and improving earthquake forecasting. However, this variation is not well understood. Here we present remarkable MFD variability during the complex 2016/17 central Italy sequence using a high-resolution earthquake catalog. Isolating seismically active volumes (‘clusters’) reveals that the MFD differed in nearby clusters, varied or remained constant in time depending on the cluster, and increased in b-value in the cluster where the largest earthquake eventually occurred. These findings suggest that the fault system’s heterogeneity and complexity influence the MFD. Our findings raise the question “b-value of what?”: interpreting and using MFD variability needs a spatiotemporal scale that is physically meaningful, like the one proposed here

A Sizing Procedure for the DC-Side Capacitor of a Three-Phase Modular Multilevel Converter

The integration of photovoltaic (PV) modules with a modular multilevel converter (MMC) is very interesting because it allows us to exploit the intrinsic advantages of that converter, such as modularity and high voltage quality, and to implement distributed maximum power point tracking algorithms. The latter can appropriately be performed through controlling the circulating currents. In the literature, some control strategies for both the AC and DC circulating currents were proposed to manage the power mismatch among the legs and between the arms of the MMC. In a previous work, the authors proposed a novel control strategy for the circulating current components and inserted a capacitor on the DC side of a three-phase MMC with integrated PV panels. In the present work, it is shown how the correct sizing of this capacitor is essential to optimize the AC circulating voltages and minimize converter losses. A sizing procedure is proposed, deeply analyzed, and validated through numerical simulations

3-D spatial cluster analysis of seismic sequences through density-based algorithms

With seismic catalogues becoming progressively larger, extracting information becomes challenging and calls upon using sophisticated statistical analysis. Data are typically clustered by machine learning algorithms to find patterns or identify regions of interest that require further exploration. Here, we investigate two density-based clustering algorithms, DBSCAN and OPTICS, for their capability to analyse the spatial distribution of seismicity and their effectiveness in discovering highly active seismic volumes of arbitrary shapes in large data sets. In particular, we study the influence of varying input parameters on the cluster solutions. By exploring the parameter space, we identify a crossover region with optimal solutions in between two phases with opposite behaviours (i.e. only clustered and only unclustered data points). Using a synthetic case with various geometric structures, we find that solutions in the crossover region consistently have the largest clusters and best represent the individual structures. For identifying strong anisotropic structures, we illustrate the usefulness of data rescaling. Applying the clustering algorithms to seismic catalogues of recent earthquake sequences (2016 Central Italy and 2016 Kumamoto) confirms that cluster solutions in the crossover region are the best candidates to identify 3-D features of tectonic structures that were activated in a seismic sequence. Finally, we propose a list of recipes that generalizes our analyses to obtain such solutions for other seismic sequences

Cognitive-enhancing effects of aripiprazole: a case report

Patients with schizophrenia often present mild to severe cognitive deficits which contribute to their social disability. Second-generation antipsychotics have shown only mild to moderate beneficial effects on cognition. The present case report suggests cognitive enhancing effects of aripiprazole, a dopamine partial agonist, shown to increase dopamine release in prefrontal cortex in animal studies

Functional Ca2+ Channels between Channel Clusters are Necessary for the Propagation of IP3R-Mediated Ca2+ Waves

The specificity and universality of intracellular Ca2+ signals rely on the variety of spatio-temporal patterns that the Ca2+ concentration can display. Ca2+ release into the cytosol through inositol 1,4,5-trisphosphate receptors (IP 3 Rs) is key for this variety. The opening probability of IP3Rs depends on the cytosolic Ca2+ concentration. All of the dynamics are then well described by an excitable system in which the signal propagation depends on the ability of the Ca2+ released through one IP3R to induce the opening of other IP3Rs. In most cell types, IP3Rs are organized in clusters, i.e., the cytosol is a "patchy" excitable system in which the signals can remain localized (i.e., involving the release through one or more IP3Rs in a cluster), or become global depending on the efficiency of the Ca2+ -mediated coupling between clusters. The spatial range over which the signals propagate determines the responses that the cell eventually produces. This points to the importance of understanding the mechanisms that make the propagation possible. Our previous qualitative comparison between experiments and numerical simulations seemed to indicate that Ca2+ release not only occurs within the close vicinity of the clearly identifiable release sites (IP3R clusters) but that there are also functional IP3Rs in between them. In this paper, we present a quantitative comparison between experiments and models that corroborate this preliminary conclusion. This result has implications on how the Ca2+-mediated coupling between clusters works and how it can eventually be disrupted by the different Ca2+ trapping mechanisms.Fil: Piegari, Estefanía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Ponce Dawson, Silvina Martha. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentin