On the Unruh effect in de Sitter space

We give an interpretation of the temperature in de Sitter universe in terms of a dynamical Unruh effect associated with the Hubble sphere. As with the quantum noise perceived by a uniformly accelerated observer in static space-times, observers endowed with a proper motion can in principle detect the effect. In particular, we study a "Kodama observer" as a two-field Unruh detector for which we show the effect is approximately thermal. We also estimate the back-reaction of the emitted radiation and find trajectories associated with the Kodama vector fields are stable.Comment: 8 pages; corrected typos; sections structure revise

Carbon Dioxide Diffuse Emission from the Soil at Vesuvio and Campi Flegrei (Pozzuoli): Ten Years of Observations

Carbon dioxide flux from the soil is regularly monitored in selected areas of Vesuvio and Solfatara (Campi Flegrei, Pozzuoli) with the main aim of investigating if the surface phenomena could provide information about the processes occurring at depth. Surveyed areas include 15 fixed points around the rim of Vesuvio and 71 fixed points in the floor of Solfatara crater, where soil CO2 flux is measured since 1998, at least once a month. In addition, two automatic permanent stations, located at Vesuvio and Solfatara, continually measure the CO2 flux and some environmental parameters that can potentially influence the CO2 diffuse degassing. We analysed, with statistical procedures, the feature of the acquired signals, evaluating the spatial and temporal variations of the CO2 degassing process. Series acquired by continuous stations are characterized by an annual periodicity that is related to the typical periodicities of some meteorological parameters (e.g., air temperature, air humidity, etc.). Such a kind of signal permits to define the “reference” level of the CO2 degassing process that diffusely affects the flanks and the base of the volcanoes. Conversely, series of CO2 flux data arising from periodic measurements over the arrays of Vesuvio and Solfatara, are less dependent on external factors such as meteorological parameters, local soil properties (porosity, hydraulic conductivity) and topographic effects (high or low ground). Therefore we argue that the longterm trend of this signal contains the “best” possible representation of the endogenous signal related to the upflow of deep hydrothermal fluids. At Vesuvio and Solfatara, the variations of these series have shown some correspondence with other physical changes of the volcanic systems

Analysis of Sustainability Propensity of Bike-Sharing Customers Using Partially Ordered Sets Methodology

The propensity for sustainability actions and awareness among population might be driven by ad hoc policies. For example, in the transportation framework, the bike is (re)gaining popularity as a mean of transportation both convenient and environmental-prone,and consequently more and more cities around the world are developing bike-sharing systems in urban areas to let their citizens be more \u2018green\u2019. Satisfaction for bike-sharing systems could be influenced in general by how the service is managed and by users\u2019 attitudes towards sustainability:if users\u2019 participation in sustainability is high, then the level of satisfaction will increase and the service will result more successful. In this paper we analyze the connection between propensity and orientation towards sustainability and satisfaction for a particular bike-sharing system via Partially Ordered Sets based methodology

Web-based randomised controlled trials in orthodontics

Randomised controlled trials (RCT) are considered the best source of scientific evidence--the gold standard--when evaluating the efficacy of orthodontic treatments. Frequently, RCT are planned as multicentre trials, with the intention of increasing statistical power and raising the precision of outcome estimates. The management of large-scale RCT, however, requires even more thorough organisation than conventional RCT. Indeed, the need for high accuracy and standardisation in data collection, research aids, secretarial skills, staff and patient training, and organisational meetings, make these studies time-consuming, expensive and, in general, relatively complex to carry out well. A website was developed to support a large scale-orthodontic RCT which aimed to evaluate the efficacy of a functional appliance(www.ortodonzia.unina.it). Websites such as this can increase the quality of data collection, simplify the randomisation process, speed up data collection, and improve trial monitoring. Web-based RCT have the potential to help globalise orthodontic research and also increase our rate of acquisition of evidence in orthodontics

MODELING OF THE THERMAL STATE OF MT. VESUVIUS FROM 1631 AD

The last eruptive event at Mt. Vesuvius occurred in 1944 AD, ending a cycle of continuous eruptive activity started with the sub-plinian event of 1631 AD. The aim of this research is i) to model the thermal evolution of the volcanic system from 1631 AD up to the present and ii) to investigate the possible process leading the volcano to the current state of quiescence. A finiteelement software is employed to solve the time-dependent energy equation and obtain the thermal field in the volcanic edifice and the surrounding medium. Volcanological, petrological and geophysical constraints are used to define the crustal structure beneath the volcanic edifice, the magma supply system active since 1631 AD, and the physico-chemical conditions of magma. Thermodynamic properties of magma and wall rocks have been evaluated from well-established thermo-chemical compilations and data from the literature. It is shown that heat transfer due to magma degassing is required in addition to the heat conduction in order to obtain transient depthtemperature fields consistent with geochemical observations, high crustal magnetization, and rigid behavior of the shallow crust as indicated by geophysical data. Surface data of carbon dioxide soil flux coming out from the Mt. Vesuvius crater are taken to constrain such an additional heat flux. The agreement between modeled and measured temperatures at the crater since 1944 AD proves the consistency of the model. It is concluded that the present state of quiescence of Mt. Vesuvius is mostly a consequence of the absence of magma supply from the deep reservoir into the shallower system. This allows the cooling of residual magma left within the volcanic conduit and the transition from continuous eruptive activity to the condition of conduit obstruction. In this scenario, the hydrothermal system may have developed subsequent to the cooling of the magma within the conduit. Our findings are a direct consequence of the high concentration of CO2 in the most mafic Vesuvian magmas: the low solubility of CO2, with respect to H2O, enables a high mass flux of carbon dioxide through the volcanic edifice. The results of this study are relevant for hazard assessment at Vesuvius and indicate directions for further investigation, such as the role of the hydrothermal system on the thermal energy budget of the volcanic system and its relationships with fluids released by crustal structures likely to host the magmatic reservoir. In general, the role of the high concentration of carbon dioxide in magmas should be more questioned and investigated when studying the behavior of volcanic systems, particularly in South Italy volcanoes

Temperature and pressure gas geoindicators at the Solfatara fumaroles (Campi Flegrei)

Long time series of fluid pressure and temperature within a hydrothermal system feeding the Solfatara fumaroles are investigated here, on the basis of the chemical equilibria within the CO2-H2O-H2-CO gas system. The Pisciarelli fumarole external to Solfatara crater shows an annual cycle of CO contents that indicates the occurrence of shallow secondary processes that mask the deep signals. In contrast, the Bocca Grande and Bocca Nova fumaroles located inside Solfatara crater do not show evidence of secondary processes, and their compositional variations are linked to the temperature–pressure changes within the hydrothermal system. The agreement between geochemical signals and the ground movements of the area (bradyseismic phenomena) suggests a direct relationship between the pressurization process and the ground uplift. Since 2007, the gas geoindicators have indicated pressurization of the system, which is most probably caused by the arrival of deep gases with high CO2 contents in the shallow parts of the hydrothermal system. This pressurization process causes critical conditions in the hydrothermal system, as highlighted by the increase in the fumarole temperature, the opening of new vents, and the localized seismic activity. If the pressurization process continues with time, it is not possible to rule out the occurrence of phreatic explosions

ATLAS RPC Quality Assurance results at INFN Lecce

The main results of the quality assurance tests performed on the Resistive Plate Chamber used by the ATLAS experiment at LHC as muon trigger chambers are reported and discussed. Since July 2004, about 270 RPC units has been certified at INFN Lecce site and delivered to CERN, for being integrated in the final muon station of the ATLAS barrel region. We show the key RPC characteristics which qualify the performance of this detector technology as muon trigger chamber in the harsh LHC enviroments. These are dark current, chamber efficiency, noise rate, gas volume tomography, and gas leakage.Comment: Comments: 6 pages, 1 table, 9 figures Proceedings of XXV Physics in Collision-Prague, Czech Republic, 6-9 July 200

ATLAS RPC Cosmic Ray Teststand at INFN Lecce

We describe the design and functionality of the cosmic ray teststand built at INFN Lecce for ATLAS RPC quality control assurance.Comment: XXIV Physics in Collisions Conference (PIC04), Boston, USA, June 2004, 3 pages, LaTex, 2 eps figures. MONP0

Single Event Effects in the Pixel readout chip for BTeV

In future experiments the readout electronics for pixel detectors is required to be resistant to a very high radiation level. In this paper we report on irradiation tests performed on several preFPIX2 prototype pixel readout chips for the BTeV experiment exposed to a 200 MeV proton beam. The prototype chips have been implemented in commercial 0.25 um CMOS processes following radiation tolerant design rules. The results show that this ASIC design tolerates a large total radiation dose, and that radiation induced Single Event Effects occur at a manageable level.Comment: 15 pages, 6 Postscript figure