The cosmic rays flux from the Pierre Auger Observatory data

L'Osservatorio Pierre Auger sta esplorando i misteri dei raggi cosmici di altissima energia. Questo esperimento è stato concepito da più di dieci anni per esplorare le proprietà dei raggi cosmici più energetici, come il flusso, la distribuzione e la direzione di arrivo, la composizione in massa, il tutto con una elevata significatività statistica e studiando l'intero cielo. Pochi anni dopo che Penzias e Wilson hanno stabilito l'esistenza del fondo cosmico di radiazione che ha una temperatura media di 2,7 K, Greisen, Zatsepin e Kuzmin previsero la soppressione del flusso dei raggi cosmici di alta energia dovuta alla loro interazione con questo fondo cosmico. Prima dell’Osservatorio Pierre Auger gli esperimenti AGASA ed Hires hanno ottenuto risultati contrastanti per quanto riguarda questa soppressione. Questi esperimenti utilizzano tecniche di rilevamento differenti. L'esperimento Auger è un rivelatore “ibridio”, nel senso che utilizza per la prima volta entrambe le tecniche. È costituito da due rivelatori progettati per osservare, in coincidenza, lo sciame di particelle che si può sviluppare lungo diversi chilometri quando raggiunge la superficie terrestre. Il rivelatore di superficie (SD) è composto di 1600 stazioni di Cherenkov che campionano il fronte dello sciame a terra. Il rivelatore a fluorescenza (FD) è dotato di 24 telescopi di fluorescenza che rilevano la luce emessa dalle molecole di azoto atmosferico eccitate dallo sciame, mentre attraversa l'atmosfera. Il FD misura il profilo longitudinale dello sciame. L’Osservatorio nell’emisfero Sud è in Argentina vicino la città di Malargüe ed è stato completato nel Maggio 2008 ed inaugurato nel Novembre 2008. L’Osservatorio è in presa dati in modo stabile dal Gennaio 2004. Durante questo tempo l'esperimento ha accumulato una quantità di dati senza precedenti ed i primi risultati sono stati pubblicati. L'Osservatorio nell’emisfero Nord sarà costruito in Colorado, negli Stati Uniti d'America. Gli osservatori insieme consentiranno una completa copertura del cielo. L'obiettivo principale di questa tesi è la misurazione dello spettro dei raggi cosmici di energia superiore ai 3 EeV sulla base dei dati registrati presso l'Osservatorio Pierre Auger.The Pierre Auger Observatory is exploring the mysteries of the highest-energy cosmic rays. This experiment was conceived more than ten years ago to explore the properties of the most energetic cosmic rays such as the flux, arrival direction distribution and mass composition, with high statistical significance and covering the whole sky. A few years after Penzias and Wilson established the existence of the cosmic microwave background with a mean temperature of 2.7 K , Greisen, Zatsepin and Kuzmin predicted that a cutoff of the cosmic ray flux at the highest energies is expected due to the interaction of the ultra high energy cosmic rays with the cosmic microwave background photons. Before the Pierre Auger Observatory the AGASA and Hires experiments have obtained differents results about this cutoff. Those experiments use different detection techniques. The Auger experiment is an “hybrid” detector in the sense that uses for the first time both techniques. It consists of two complementary detectors designed to observe, in coincidence, the shower of particles which can be spread along several kilometres when they reach the earth surface. A Surface Detector (SD) composed of 1600 Cherenkov stations samples the front of the shower at ground. A Fluorescence Detector (FD) equipped with 24 telescopes collects the fluorescence light emitted by atmospheric nitrogen molecules excited as the shower is crossing the atmosphere. The FD measure the longitudinal profile of the shower. The Southern Observatory in Argentina near the Malargüe village was completed in May 2008 and inaugurated in November 2008. It is taking data in stable manner since January 2004. During this time the experiment has accumulated an unprecedented statistics and the first results are pubblished. The Northern Observatory will be built in Colorado, USA. Both observatories allow a full sky coverage. The main objective of this thesis is the measurement of the cosmic ray energy spectrum above 3 EeV based on the data recorded at the Pierre Auger Observatory

1D Dynamic Non-Linear Numerical Analysis of Earth Slopes: The Role of Soil Ductility and Time-Sensitiveness

The mechanical response of dry granular slopes subjected to dynamic perturbations is tackled from a theoretical/numerical viewpoint. A 1D geometrical/numerical scheme is adopted to analyze infinitely long strata: the dynamic activation of shallow translational failure mechanisms (as well as the displacement performance far from collapse) is analyzed by means of a self-made FEM code. The soil mechanical behavior is described by means of a simplified viscoplastic one-dimensional constitutive model, capable of reproducing both ductile (hardening) and brittle (softening) mechanical responses. The dependence of numerical results on the soil “time-sensitiveness”, as well as the differences between viscoplasticity and standard rate-independent plasticity, is discussed. For the case of impulse-like loads (Ricker wavelets), the influence of the ratio between the dominant wavelength and the stratum thickness on the overall deformation mechanism is commented. The response of the slope to a real accelerometric record is finally illustrated

1D Dynamic Non-Linear Numerical Analysis of Earth Slopes: The Role of Soil Ductility and Time-Sensitiveness

The mechanical response of dry granular slopes subjected to dynamic perturbations is tackled from a theoretical/numerical viewpoint. A 1D geometrical/numerical scheme is adopted to analyze infinitely long strata: the dynamic activation of shallow translational failure mechanisms (as well as the displacement performance far from collapse) is analyzed by means of a self-made FEM code. The soil mechanical behavior is described by means of a simplified viscoplastic one-dimensional constitutive model, capable of reproducing both ductile (hardening) and brittle (softening) mechanical responses. The dependence of numerical results on the soil “time-sensitiveness”, as well as the differences between viscoplasticity and standard rate-independent plasticity, is discussed. For the case of impulse-like loads (Ricker wavelets), the influence of the ratio between the dominant wavelength and the stratum thickness on the overall deformation mechanism is commented. The response of the slope to a real accelerometric record is finally illustrated

Mucosal adhesion and anti-inflammatory effects of Lactobacillus rhamnosus GG in the human colonic mucosa. A proof-of-concept study

AIM To investigate the adhesion and anti-inflammatory effects of Lactobacillus rhamnosus GG (LGG) in the colonic mucosa of healthy and ulcerative colitis (UC) patients, both in vivo and ex vivo in an organ culture model. METHODS For the ex vivo experiment, a total of 98 patients (68 UC patients and 30 normal subjects) were included. Endoscopic biopsies were collected and incubated with and without LGG or LGG-conditioned media to evaluate the mucosal adhesion and anti-inflammatory effects [reduction of tumor necrosis factor alpha (TNFa) and interleukin (IL)-17 expression] of the bacteria, and extraction of DNA and RNA for quantification by real-time (RT)-PCR occurred after the incubation. A dose-response study was performed by incubating biopsies at "regular", double and 5 times higher doses of LGG. For the in vivo experiment, a total of 42 patients (20 UC patients and 22 normal controls) were included. Biopsies were taken from the colons of normal subjects who consumed a commercial formulation of LGG for 7 d prior to the colonoscopy, and the adhesion of the bacteria to the colonic mucosa was evaluated by RT-PCR and compared with that of control biopsies from patients who did not consume the formulation. LGG adhesion and TNFa and IL-17 expression were compared between UC patients who consumed a regular or double dose of LGG supplementation prior to colonoscopy. RESULTS In the ex vivo experiment, LGG showed consistent adhesion to the distal and proximal colon in normal subjects and UC patients, with a trend towards higher concentrations in the distal colon, and in UC patients, adhesion was similar in biopsies with active and quiescent inflammation. In addition, bioptic samples from UC patients incubated with LGG conditioned media (CM) showed reduced expression of TNFa and IL-17 compared with the corresponding expression in controls (P < 0.05). Incubation with a double dose of LGG increased mucosal adhesion and the anti-inflammatory effects (P < 0.05). In the in vivo experiment, LGG was detectable only in the colon of patients who consumed the LGG formulation, and bowel cleansing did not affect LGG adhesion. UC patients who consumed the double LGG dose had increased mucosal concentrations of the bacteria and reduced TNFa and IL-17 expression compared with patients who consumed the regular dose (48% and 40% reduction, respectively, P < 0.05). CONCLUSION In an ex vivo organ culture model, LGG showed consistent adhesion and anti-inflammatory effects. Colonization by LGG after consumption for a week was demonstrated in vivo in the human colon. Increasing the administered dose increased the adhesion and effectiveness of the bacteria. For the first time, we demonstrated that LGG effectively adheres to the colonic mucosa and exerts antiinflammatory effects, both ex vivo and in vivo

Impact of dry granular masses on rigid barriers

This work concerns the impact of dry granular masses on rigid artificial obstacles. The authors approached the problem by performing an extensive campaign of numerical analyses with a commercial code based on the discrete element theory. The standard approaches employed to design sheltering structures are exclusively based on the assessment of the Maximum Impact Force (MIF) exerted by the soil mass on the obstacle, and the sheltering structure is usually designed according to simplified pseudo-static approaches. In a previous paper the authors considered the dependence of MIF on the Froude number and on a large series of both geometrical and mechanical parameters. Indeed, the impulsive nature of the force exerted by the soil onto the structure has to be considered in order to optimize the design of this type of structures. For this reason in this paper the evolution with time of the impact force and the mechanics of the phenomenon are investigated

Tourism as a tool for natural hazard protection and territory development: Civita di Bagnoregio (Viterbo, Italy) as a case study

The village of Civita di Bagnoregio (Viterbo, Italy) represents a surreal landscape generated by accelerated soil erosion. The active landslides and erosive phenomena which are affecting Civita contributed to the progressive reduction of its surface and to its depopulation and currently require advanced engineering solutions to mitigate their impact. Furthermore they contributed to internationally increase the village fame, resulting in an increasing number of visitors over last years. The increasing touristic pressure on the village has been evaluated by taking into account also possible rising due to the recent candidature of Civita di Bagnoregio to the UNESCO’s World Heritage List (WHL). The high touristic pressure is triggering new critical issues highlighting the absence of a proper management plan: the data analysis highlighted the need to develop appropriate tourist numbers management strategies, considering also a partial re-investment of entrance fees for activities aimed to safeguard the village. The present research highlight that effects of tourist flows attracted by Civita di Bagnoregio could substantially contribute to both the safeguard of the village and the economical development of the territory. Properly distributed in the area by planning tourism decentralization policies based on an integrated valorisation of the territory it would be also possible to expand benefits deriving from the tourism sector to the entire Teverina area, transforming a stress factor into a development vector for the whole territory and the local population

Physical state of water controls friction of gabbro-built faults

: Earthquakes often occur along faults in the presence of hot, pressurized water. Here we exploit a new experimental device to study friction in gabbro faults with water in vapor, liquid and supercritical states (water temperature and pressure up to 400 °C and 30 MPa, respectively). The experimental faults are sheared over slip velocities from 1 μm/s to 100 mm/s and slip distances up to 3 m (seismic deformation conditions). Here, we show with water in the vapor state, fault friction decreases with increasing slip distance and velocity. However, when water is in the liquid or supercritical state, friction decreases with slip distance, regardless of slip velocity. We propose that the formation of weak minerals, the chemical bonding properties of water and (elasto)hydrodynamic lubrication may explain the weakening behavior of the experimental faults. In nature, the transition of water from liquid or supercritical to vapor state can cause an abrupt increase in fault friction that can stop or delay the nucleation phase of an earthquake

Impact of different driving cycles and operating conditions on CO2 emissions and energy management strategies of a Euro-6 hybrid electric vehicle

Although Hybrid Electric Vehicles (HEVs) represent one of the key technologies to reduce CO2 emissions, their effective potential in real world driving conditions strongly depends on the performance of their Energy Management System (EMS) and on its capability to maximize the efficiency of the powertrain in real life as well as during Type Approval (TA) tests. Attempting to close the gap between TA and real world CO2 emissions, the European Commission has decided to introduce from September 2017 theWorldwide Harmonized Light duty Test Procedure (WLTP), replacing the previous procedure based on the New European Driving Cycle (NEDC). The aim of this work is the analysis of the impact of different driving cycles and operating conditions on CO2 emissions and on energy management strategies of a Euro-6 HEV through the limited number of information available from the chassis dyno tests. The vehicle was tested considering different initial battery State of Charge (SOC), ranging from 40% to 65%, and engine coolant temperatures, from 7 C to 70 C. The change of test conditions from NEDC to WLTP was shown to lead to a significant reduction of the electric drive and to about a 30% increase of CO2 emissions. However, since the specific energy demand of WLTP is about 50% higher than that of NEDC, these results demonstrate that the EMS strategies of the tested vehicle can achieve, in test conditions closer to real life, even higher efficiency levels than those that are currently evaluated on the NEDC, and prove the effectiveness of HEV technology to reduce CO2 emissions