168 research outputs found
Cromo (VI) nei cementi e implementazione del regolamento REACH: metodo di screening a supporto delle attività di controllo
No full textGrown-up celiac children: effects of few years on a gluten-free diet in childhood
No full textDESCRIVE LO STATO DI SALUTE E DELLA MASSA OSSEA DI ADULTI CHE DA BAMBINI HANNO AVUTO DIAGNOSI DI CELIACHIA E POI, DOPO QUALCHE ANNO-- COME UN TEMPO SI FACEVA-- HANNO SOSPESO LA DIETA SENZA GLUTINE
Prevalenza del diabete gestazionale per epoca di gravidanza negli anni compresi fra il 1990 e il 1997
No full textConfronto fra eventi condizionati di probabilità nulla nell'inferenza statistica bayesiana
No full textBy a suitable extension of the usual algebra of events, logical operations forconditional events are introduced. This leads to a definition of conditional iperprobability , which is the natural tool for a sensible interpretation of the concept of conditional pseudodensity, introduced by R. Scozzafava in Bayesian statistical inference
Comparison among un-denuder filter based, denuder filter pack and continuous techniques for inorganic artefact assessment
No full textThe particulate matter consists of thousands of chemical species characterized by several physical and chemical properties. Sulphate, nitrate and ammonium are the main components of the inorganic fraction and account for 30-40% of total mass of PM2.5 (Minguillóna et al., 2012). Traditionally in measuring the ambient concentrations of aerosols, water-soluble inorganic fraction of PM are determined by filter-based method. This method has several shortcomings such as labor intensity, lengthy analysis time, poor resolution time and the sampling artefacts. The most studied sampling artefact regards the nitrate content determined on filter. PM2.5 nitrate concentrations, in fact, can result overestimated due to the absorption of gas-phase nitric acid on the filter, and underestimated due to the evaporation of ammonium nitrate collected on filter during the sample collection (Vecchi et al., 2009). The most rigorous methods recommended by United States Environmental Protection Agency (USEPA Compendium Method IO- 4.2) for avoiding gas/aerosol artefacts is the use of diffusion denuders and a filter pack. These denuders first denude the air stream of condensable gases and then sample the aerosols with a filter pack that can collect both the aerosol and any volatilized products from it. Nowadays semi-continuous instruments that provide data of PM ionic component have been developed. Among the most modern automated systems equipped with denuders, the Ambient Ion Monitor AIM 9000D (by URG&Co) has been used for this work. The AIM is a real-time analytical instrument capable of simultaneous sampling and measurements of water-soluble PM2.5 constituents and ion gas precursors. In this study, in order to assess the inorganic artifact and the AIM performance for avoiding them, the results obtained measuring nitrate and nitrite determined by an un-denuded filter based sampler, a denuder filter-pack sampler and a semi-continuous system have been reported. The preliminary results analysis highlighted a noticeable difference in nitrate and nitrite amount determined on 24h filters and on three 8h filters samples simultaneously; especially for nitrite concentration when lower NOx and higher Ozone concentrations were registered (for example in fig. 1 are reported only few days). Moreover, as shown in figure 2, the nitrate concentrations determined by AIM showed a good correlation with those determined by the rigorous artefact free methods based on denuder filter pack sampler. However in specific days, the particulate nitrate concentrations determined by AIM result unexpectedly lower than those determined by denuder filter pack method. In these days, characterized by higher ozone concentrations, the particulate nitrite concentrations on filter for denuder filter pack methods were very lower than those determined by AIM and usually not determined. These findings suggested a possible oxidation of nitrite to nitrate on filter during PM collection (Yu et al., 2005). Therefore, this reaction probably determines another important artefact in nitrate determination on filter. Finally, these results showed also the potentiality of the automatic instrument in nitrate artefact free measurements and taking into account the user-friendliness and lower time and cost consumption, AIM could be an useful tool for an accurate determination of PM ionic composition. Fig. 1: Comparison among nitrate amount determined on 24 and 8 hours filters. NOx and Ozone concentrations behaviour
Vecchi, R. et al., 2009. Atm. Env. 43 (2009) 1713–1720.
Minguillóna, M.C., et al. 2012. Sci.Tot.Env.427–428: 191–202
Yu et al., 2005. J. Air & Waste Manag. Ass. 55, 1100–111
Monitoraggio intensivo di Idrocarburi Policiclici Aromatici (IPA) nell’area industriale di Taranto
No full textLarea industriale di Taranto ad oggi annoverata tra le zone ad alto rischio
ambientale ed inclusa nell’elenco dei siti inquinati di interesse nazionale a causa
della presenza di un ampio complesso industriale in prossimit dell’insediamento
urbano. Nonostante gli importanti risultati conseguiti dalle politiche di controllo
delle emissioni convogliate, la complessit degli impianti che caratterizzano
larea industriale tarantina rende difficile lidentificazione e la
localizzazione delle sorgenti che contribuiscono alle emissioni diffuse e altamente
impattanti sulla qualit dellaria nelle aree urbane limitrofe.
Pertanto in questo lavoro stato effettuato un monitoraggio intensivo degli IPA nel
PM10 al fine di discriminare le diverse sorgenti diffuse e di determinare limpatto
di ciascuna esse sui siti recettori sensibili in base ai principali parametri
meteorologici che determinano la dispersione e trasporto in atmosfera degli
inquinanti.
In particolare stata condotta una campagna di monitoraggio di PM10 in 7 siti di
campionamento dislocati intorno allarea industriale tarantina e disposti lungo le
direzione dei venti dominanti. Il campionamento di PM10 per la determinazione delle
concentrazioni giornaliere di IPA, stato effettuato dal 1Gennaio al 30 Luglio 2011
con campionatori basso volume SWAM bicanale (FAI Instruments s.r.l.).
Contemporaneamente nei diversi siti sono stati monitorati le concentrazioni orarie di
IPA totali utilizzando un analizzatore in continuo (ECOCHEM PAS 2000), i principali
parametri meteo, la capacit disperdente dellatmosfera e le concentrazioni di
SO2, NOx, Benzene (B) e Toluene (T).
Lelaborazione dei dati di concentrazioni dei singoli IPA, dei rapporti diagnostici
e dei rapporti B/T mediante polar plot bivariati hanno permesso di identificare le
sorgenti di emissione diffuse e di valutarne limpatto in corrispondenza di venti
tali da permettere il trasporto degli inquinanti dallarea industriale sul sit
"Studio dei processi di formazione e trasporto del particolato atmosferico mediante il monitoraggio ad alta risoluzione temporale"
No full textEvaluation of Second-Hand Exposure to Electronic Cigarette Vaping under a Real Scenario: Measurements of Ultrafine Particle Number Concentration and Size Distribution and Comparison with Traditional Tobacco Smoke
No full textThe present study aims to evaluate the impact of e-cig second-hand aerosol on indoor air quality in terms of ultrafine particles (UFPs) and potential inhalation exposure levels of passive bystanders. E-cig second-hand aerosol characteristics in terms of UFPs number concentration and size distribution exhaled by two volunteers vaping 15 different e-liquids inside a 49 m3 room and comparison with tobacco smoke are discussed. High temporal resolution measurements were performed under natural ventilation conditions to simulate a realistic exposure scenario. Results showed a systematic increase in UFPs number concentration (part cm-3) related to a 20-min vaping session (from 6.56 X 103 to 4.01 X 104 part cm-3) although this was one up to two order of magnitude lower than that produced by one tobacco cigarette consumption (from 1.12 X 105 to 1.46 X 105 part cm-3). E-cig second-hand aerosol size distribution exhibits a bimodal behavior with modes at 10.8 and 29.4 nm in contrast with the unimodal typical size distribution of tobacco smoke with peak mode at 100 nm. In the size range 6-26 nm particles concentration in e-cig second-hand aerosol were from 2-(Dp = 25.5 nm) to 3800-fold (Dp = 9.31 nm) higher than in tobacco smoke highlighting that particles exhaled by users and potentially inhaled by bystanders are nano-sized with high penetration capacity into human airways.The present study aims to evaluate the impact of e-cig second-hand aerosol on indoor air quality in terms of ultrafine particles (UFPs) and potential inhalation exposure levels of passive bystanders. E-cig second-hand aerosol characteristics in terms of UFPs number concentration and size distribution exhaled by two volunteers vaping 15 different e-liquids inside a 49 m(3) room and comparison with tobacco smoke are discussed. High temporal resolution measurements were performed under natural ventilation conditions to simulate a realistic exposure scenario. Results showed a systematic increase in UFPs number concentration (part cm(-3)) related to a 20-min vaping session (from 6.56 x 10(3) to 4.01 x 10(4) part cm(-3)), although this was one up to two order of magnitude lower than that produced by one tobacco cigarette consumption (from 1.12 x 10(5) to 1.46 x 10(5) part cm(-3)). E-cig second-hand aerosol size distribution exhibits a bimodal behavior with modes at 10.8 and 29.4 nm in contrast with the unimodal typical size distribution of tobacco smoke with peak mode at 100 nm. In the size range 6-26 nm, particles concentration in e-cig second-hand aerosol were from 2- (Dp = 25.5 nm) to 3800-fold (Dp = 9.31 nm) higher than in tobacco smoke highlighting that particles exhaled by users and potentially inhaled by bystanders are nano-sized with high penetration capacity into human airways
A general probabilistic database model
No full textA new model for probabilistic databases, using interval-valued conditional probability assessments, is proposed. The concept of coherence adopted in our approach is based on a suitable generalization of the coherence principle of de Finetti and can be related to similar definitions given for lower and upper probabilities by other authors. A corresponding probabilistic relational algebra is introduced and some new operators are defined. Finally, some simple examples are given
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