Experimental Characterization and Numerical Investigation on the Azzone Visconti Bridge in Lecco (Italy)

AbstractThe paper presents the results of a numerical investigation on the Azzone Visconti Bridge in Lecco (Italy). Starting from the historical data and from an extensive mechanical characterization of both the soil constituting the riverbed and of the masonry constituting the piers, the aim of the analyses is to predict the behaviour of the structure under the testing loading scheme prescribed by the current Italian Code. A finite element structural model has been conceived, and three different models describing the mechanical behaviour of the foundation have been implemented. Limited differences are observed in terms of absolute vertical settlement of the bridge, but important effects are highlighted in terms of stress redistribution within the piers

The Mineralogical Study on the Cueva de Las Vegas (Naica, Mexico)

The Cueva de las Velas is the last cave unveiled at -290 level within the Naica Mine; the cavity has been intercepted by a mine gallery at the beginning of 2005. One of its peculiarities is the widespread thick deposits of diagenetic minerals deposited over the cave walls before the beginning of the evolution of the giant gypsum crystals. These deposits consist of complex, often scarcely crystalline iron-manganese-lead oxides-hydroxides, but carbonates, sulphates and silicates are also present. Other minerals, mainly sulphates, started developing just after this area of the mine was dewatered some 20 years ago. Presently 17 different minerals have been observed, 5 of which (orientite, starkeyite, szmolnokite, szmikite and woodruffite) are completely new for the cavern environment. The study of these minerals, together with the presence of a completely new type of gypsum crystals, allowed to improve the knowledge on the speleogenetic evolution of this cave, which seems to be by far more complex than that of the other cavity of the -290 level.Its complexity is reflected by the activity of a larger number of different speleogenetic mechanisms. Among them are worth of mention the thermal corrosion/dissolution, the anhydrite-gypsum disequilibrium, the acid aggression, and the capillary migration and evaporation

Peculiar Minerogenetic Cave Environments of Mexico: The Cuatro Ciénegas Area

The karst area of Quatro Ciénegas (Coahuila, Mexico) represents an ideal site to study cave mineralogy, because it hosts caves of different age and genesis (karst, thermal, mine caves). Among the speleothems studied is worth to mention a nest of aragonite cave pearls found deep inside the Reforma mine characterized by the total absence of growing layers inside them. Despite only few studied caves (8), some 32 different cave minerals have been detected, one of which is new for the cavern environment (kingsmountite) and another one, still under study, which probably will result new for science. Due to the scientific interest of their chemical deposits it should be very important to protect in the future the natural cavities of the karst systems of Cuatro Ciénegas in order to preserve a scientific patrimony, actually only partially known

Terahertz Leaky-Wave Antennas Based on Metasurfaces and Tunable Materials

Terahertz frequencies are increasingly gaining attention due to the recent efforts made in narrowing the technological gap among microwave and optical components. Still the demand of efficient THz antennas is high, due to the difficulty in obtaining directive patterns and good radiation efficiencies with planar, low-cost, easy-to-fabricate designs. In this regard, leaky-wave antennas have recently been investigated in the THz range, showing very interesting radiating features. Specifically, the combination of the leaky-wave antenna design with the use of metamaterials and metasurfaces seems to offer a promising platform for the development of future THz antenna technologies. In this Chapter, we focus on three different classes of leaky-wave antennas, based on either metasurfaces or tunable materials, namely graphene and nematic liquid crystals. While THz leaky-wave antennas based on homogenized metasurfaces are shown to be able to produce directive patterns with particularly good efficiencies, those based on graphene or nematic liquid crystals are shown to be able to dynamically reconfigure their radiating features. The latter property, although being extremely interesting, is obtained at the expense of an increase of costs and fabrication complexity, as it will emerge from the results of the presented study

Tickling the CMB damping tail: scrutinizing the tension between the ACT and SPT experiments

The Atacama Cosmology Telescope (ACT) and the South Pole Telescope (SPT) have recently provided new, very precise measurements of the cosmic microwave background (CMB) anisotropy damping tail. The values of the cosmological parameters inferred from these measurements, while broadly consistent with the expectations of the standard cosmological model, are providing interesting possible indications for new physics that are definitely worth of investigation. The ACT results, while compatible with the standard expectation of three neutrino families, indicate a level of CMB lensing, parametrized by the lensing amplitude parameter A_L, that is about 70% higher than expected. If not a systematic, this anomalous lensing amplitude could be produced by modifications of general relativity or coupled dark energy. Vice-versa, the SPT experiment, while compatible with a standard level of CMB lensing, prefers an excess of dark radiation, parametrized by the effective number of relativistic degrees of freedom N_eff. Here we perform a new analysis of these experiments allowing simultaneous variations in both these, non-standard, parameters. We also combine these experiments, for the first time in the literature, with the recent WMAP9 data, one at a time. Including the Hubble Space Telescope (HST) prior on the Hubble constant and information from baryon acoustic oscillations (BAO) surveys provides the following constraints from ACT: N_eff=3.23\pm0.47, A_L=1.65\pm0.33 at 68% c.l., while for SPT we have N_eff=3.76\pm0.34, A_L=0.81\pm0.12 at 68% c.l.. In particular, the A_L estimates from the two experiments, even when a variation in N_eff is allowed, are in tension at more than 95% c.l..Comment: 7 pages, 7 figures, v.2. some typos and sentences correcte

Robertsite: un nuovo fosfato di grotta scoperto nella Tagusan Cave(Palawan – Filippine)

La Tagusan Cave è una cavità di attraversamento che si apre nel massiccio calcareo che ospita la famosa grotta Porto Pricesa Undergroud River nell’isola di Palawan (Filippine). Al suo interno sono state rivenute alcune pisoliti di colore nero che sono state campionate e quindi analizzate dal punto di vista tessiturale e mineralogico. Le analisi al microscopio ottico hanno evidenziato come queste pisoliti non siano omogenee ma siano costituite da un nucleo spesso costituito da una aggregazione di ooliti giallastre su cui si è depositata un’alternanza di sottili strati picei e rossastri. L’analisi mineralogica delle bande di accrescimento ha evidenziato la presenza, oltre a fosfati di calcio praticamente amorfi, di robertsite [Ca2Mn3(PO4)3O2•3H2O], un fosfato che non era mai stato segnalato prima in grotta. Sempre in queste bande, sulla base degli esami röntgenografici e delle analisi EDAX, si è ipotizzata la presenza anche di janggunite [Mn5-x(Mn,Fe)1-xO8(OH)6], di cui però non si è raggiunta la certezza. Nel nucleo invece è stato possibile identificare la presenza di strengite-Al [(Fe,Al) (PO4) •2H2O]. La genesi di queste particolari pisoliti è da mettere in relazione con i processi di digestione biologica del guano che all’inizio della loro evoluzione doveva essere abbondante nelle acque che fluivano nella grotta, mentre ora, l’apporto idrico è molto più scarso e proviene da stillicidi che hanno scarsa relazione con il guano medesimo.The Tagusan cave is a hydrologic tunnel in the karst massif hosting the famous Porto Pricesa Underground River in the Palawan Island (Philippines). It hosts some speleothems among which are worth to be cited some black pearls. A few of them have been sampled to be analyzed from the textural and mineralogical point of view. The optical microscope analyses put in evidence that the inner structure of these pearls is un-homogeneous, consisting of a nucleus often made by aggregates of yellowish oolites covered by alternated pitch-dark and reddish layers. The mineralogical analyses find out that the growing layers consist of amorphous phosphates and robertsite [Ca6Mn9(PO4)9O6(H2O)6•3(H2O)], which is here recognized, for the first time, as cave mineral. The x-ray patterns and the EDAX analyses suggest also the presence of janggunite [Mn5-x(Mn,Fe)1-xO8(OH)6], but no definitive proof of it has been yet achieved. Strengite-Al, [(Fe,Al)PO4•2H2O)] is the main component of the yellowish oolites in the pearl’s nucleus. The genesis of these peculiar cave pearls is strictly related to the biological digestion processes of the guano deposits. In fact at the beginning of their evolution the feeding water directly crossed guano deposits, while now the few still active dripping practically has no contact with it

Robust Train Routing and Online Re-scheduling

Train Routing is a problem that arises in the early phase of the passenger railway planning process, usually several months before operating the trains. The main goal is to assign each train a stopping platform and the corresponding arrival/departure paths through a railway station. It is also called Train Platforming when referring to the platform assignment task. Railway stations often represent bottlenecks and train delays can easily disrupt the routing schedule. Thereby railway stations are responsible for a large part of the delay propagation in the whole network. In this research we present different models to compute robust routing schedules and we study their power in an online context together with different re-scheduling strategies. We also design a simulation framework and use it to evaluate and compare the effectiveness of the proposed robust models and re-scheduling algorithms using real-world data from Rete Ferroviaria Italiana, the main Italian Railway Infrastructure Manager

A Low-cost Sensing System for Cooperative Air Quality Monitoring in Urban Areas

Air quality in urban areas is a very important topic as it closely affects the health of citizens. Recent studies highlight that the exposure to polluted air can increase the incidence of diseases and deteriorate the quality of life. Hence, it is necessary to develop tools for real-time air quality monitoring, so as to allow appropriate and timely decisions. In this paper, we present uSense, a low-cost cooperative monitoring tool that allows knowing, in real-time, the concentrations of polluting gases in various areas of the city. Specifically, users monitor the areas of their interest by deploying low-cost and low-power sensor nodes. In addition, they can share the collected data following a social networking approach. uSense has been tested through an in-field experimentation performed in different areas of a city. The obtained results are in line with those provided by the local environmental control authority and show that uSense can be profitably used for air quality monitoring

Fish parasites resolve the paradox of missing coextinctions.

Models of coextinction identify parasites as one of the most menaced ecological groups. The number of host species a parasite uses should strongly affect its risk of coextinction. The naïve expectation is that the lower the number, the higher is the parasite's risk of being left with no hosts. Here we analyse the coextinction risk of 12,141 fish parasite species and find that highly specific parasites are not the most endangered, because they tend to use hosts with low vulnerability to extinction. This unexpected result may explain why the number of documented host-parasite coextinctions is much lower than predicted by theoretical studies. © 2013 Macmillan Publishers Limited. All rights reserved