121,916 research outputs found
Sardegna, Continuità Territoriale aerea: allineamento tariffario per gli utenti, residenti e non residenti
No full textIl Modello EDMS: Controllo degli elementi Inquinanti in un Ciclo LTO Aeronautico
No full textNell’ambito delle politiche e delle scelte per lo sviluppo degli scali aeroportuali, è necessario oggi giorno tenere in massima considerazione, oltre che i parametri socio-economici e trasportistici, anche le valutazioni sulla tutela del patrimonio ambientale. Se per ciò che riguarda il rumore molti studi e ricerche sono state effettuate, sia dal punto di vista tecnico che normativo, non altrettanto si può dire per le emissioni di sostanze inquinanti durante un ciclo LTO Il presente lavoro si propone di studiare e analizzare il tema delle emissioni inquinanti in ambito aeroportuale; l’attenzione si è concentrata nella fase più critica che interessa più propriamente un’infrastruttura aeroportuale e il suo intorno, e precisamente il Landing Take Off cycle, o LTO come definito dall’ICAO. Per affrontare tale problema, che nel seguito potrà avere una sua applicazione nella realtà fisica dell’aeroporto di Cagliari-Elmas, si è ricorso ad un modello elaborato dalla F.A.A: Emissions and Dispersion Modeling System –EDMS-.
Una volta raccolti i dati relativi all’intera movimentazione degli aeromobili, individuate tutte le sorgenti di emissioni che interessano il sedime aeroportuale(aeromobili, mezzi di rampa, veicoli in entrata/uscita dalla aerostazione), il modello consente, in un primo tempo, di generare un inventario delle emissioni.ed in un secondo momento di prevedere la dispersione nell’atmosfera.
. Per una verifica più corretta sul suo funzionamento nel proseguo di una prossima ricerca sarà prodotta una simulazione dinamica relativa all’aeroporto di Cagliari –Elmas, per quanto riguarda specificatamente le emissioni, calibrando appositamente il modello in studio, i cui risultati saranno esposti nel lavoro finale
“Airport charges regulation: a model for tariff calculation”
No full textThe present study is concerned with a highly topical issue in air transportation, namely the regulation of charges for airport services provided by sole airport operators.
In 2005 the Italian parliament passed Law 248/05 concerning the reform of airport services regulation. This law envisages that maximum increases in airport charges shall be regulated by a mixed single till price cap mechanism. With this scheme, known as shared till, a quota of no less than half of the additional profit margin shall contribute to reducing aviation operations costs to be remunerated through airport charges.
The regulatory framework envisaged by Law 248/05 was definitively approved in June 2007.
In this paper the regulations applied in Italy will be described in detail, analysing in particular the implementation guidelines issued by the regulator ENAC. Based on these guidelines calculation algorithms will be derived and constructed for implementing an application able to provide the operator with the prices of the regulated services, according to the mechanisms envisaged by law..
The creation of a model of this type is all the more necessary because prices are reviewed every four years (length of the regulatory period)
L.C. & TOURISM: Analysis of users of international low cost flights from Cagliari-Elmas airport
No full text
Analisi sperimentale dell’efficienza di una rete di trasporto aereo attraverso la costruzione di un modello di calcolo degli indici prestazionali
No full textA mathematical model for distribution of air transport demand: the case of the Sardinian network
No full textRokitamycin loaded microparticles based on chitosan for the therapy of amoebic infections.
No full textOBJECTIVES
The aims of this study were: i) to assess the
feasibility of using biodegradable chitosan
microspheres as carriers for controlled release of
rokitamycin (RK), able to improve the antiamoebic
activity of the drug;i ii) to investigate the preparative
parameters for obtaining microspheres based on
chitosan (CH) suitable for ocular or nasal
administration of rokitamycin;ii iii) to verify if it was
possible to maintain microsphere characteristics
suitable for ocular or nasal administration using water
soluble polymers such as new chitosan derivatives,
diethylaminomethyl-(diethyldimethylene ammonium)n
methylchitosans (C7 and C8) or CH salt, chitosan
glutamate (CG);ii iv) to evaluate the influence of
chitosan properties (CH vs CG) on the in vivo
rokitamycin absorption, after nasal administration of
spray dried microspheres.iii
METHODS
Preparation of spray dried microspheres.
Microsphere formulations based on CH or C7 or C8 or
CG were prepared by spray drying (Mini Büchi B-191,
Büchi Laboratoriums-Technik AG, Flawil,
Switzerland) using different drug–polymer ratios (1–3
and 1–4) and starting from feed solutions with diverse
concentrations (1.5%, 1%, 0.5% and 0.25% (w/v)).
Characterisation of Microspheres. Microparticles
prepared were characterised in terms of yield of
production, drug loading and encapsulation efficiency,
particle size, morphology, in vitro drug release, water
uptake, in vitro mucoadhesion, ex vivo drug
permeation, Energy Dispersive X-ray Diffraction
(EDXD) measurements.
Determination of effects of drug and microspheres
on Acanthamoeba growth. Loaded and unloaded CH
microspheres were dispersed in PYG medium and
applied on trophozoite grown in sterile 24-well plates
(Corning). At selected time intervals (3, 4, 7, 9 and 15
days of incubation), amoebas growing in each well
were counted in a Nageotte chamber, using the inverted
microscope.
In vivo RK administration. Nasal administration of
CG and CH microparticles containing RK to each
nostril of the anaesthetized Male Wistar rats was
performed by use of single dose Monopowder P®
insufflators (Valois Dispray). At predetermined times,
blood and liquor samples were collected and analyzed.
Results were compared with those obtained after
intravenous infusion of RK and nasal administration of
RK aqueous suspension.
CONCLUSIONS
The loading of RK into CH microspheres improves
and prolongs the in vitro antiamoebic activity of the
drug.i CH based microspheres with good morphology
and narrow size distribution, able to increase the
dissolution rate of RK, can be obtained by spray drying
using a low concentration of feed solution and 1-4
drug–polymer ratio.ii RK encapsulation into CH
microspheres increases its poor ex vivo permeability
through nasal sheep mucosa. The encapsulation of RK
in C7 and C8 by using the chosen parameters results in
microparticles showing similar or often better
properties than formulations made by CH with respect
to size, in vitro release behaviour and
mucoadhesiveness.ii
Compared with CH particles, CG microspheres
load the drug in amorphous form, leading to the best
improvement of its water solubility. This property, as
well as the rapid water uptake of CG particles,
increases more the release rate of the drug from
microspheres and only after their in vivo nasal
administration, RK goes to the cerebrospinal fluid and
the bloodstream.iii
ACKNOWLEDGEMENTS
This work was supported by MiUR through grant
PRIN05 and Fondazione Banco di Sardegna. The
authors thank “Farmaceutici Formenti S.p.A” and
Valois Pharma for the donation of RK and the powder
insufflators, respectively.
REFERENCES
i Rassu, G., Gavini, E., Mattana, A., Giunchedi, P. Open
Drug Del J, 2, 38-43, 2008.
ii Rassu, G., Gavini, E., Jonassen, H., Zambito, Y., Fogli, S.,
Breschi, MC, Giunchedi, P. J. Pharm. Sci., 98, 4852-4865,
2009.
iii Gavini, E., Rassu, G., Ferraro, L., Generosi, A., Rau, JV.,
Brunetti, A., Giunchedi, P., Dalpiaz, A. J. Pharm. Sci., In
Press
A mathematical model for demand distribution in an air transport network: an application to Sardinia
No full textThis article describes the great distance that separates Sardinia from mainland Italy has made the island – the second largest island of the Mediterranean – a marginal and remote region. Its system of ferry links for people travelling to and from Sardinia has such long journey times (8-12 hours) that it is clearly in no way a valid alternative to air transport. It was mainly on the basis of these reasons and with a view to protecting and ensuring the mobility of Sardinian residents that Public Service Obligations (PSO) were imposed on some of the main air routes starting from 2002. Our study is set against this background. It aims to resolve one of the main critical factors that distinguish the PSO network: the shortage of flights on certain routes and the concomitant over-scheduling of others. More specifically, the insufficient scheduling of weekly flights to certain airports, such as Verona and Turin, forces a number of passengers to decide not to travel at all and another part to use connecting flights to Rome/Milan airports or to travel using more than one route, via air or ground transport, with inevitably higher transport costs. The problem was addressed by using a linear scheduling model applied to a network of nodes and arcs representing, respectively, the airports and their connecting routes, and the airport of Cagliari. The decision variables identified were the number of passengers travelling on all of the arcs and the impedance measures associated with the distance travelled by the arcs, represented by the generalized cost of transport. The objective is to determine a network structure which corresponds to the distribution of passengers on the various branches capable of minimizing the total cost. This cost was considered as a useful parameter for comparing the various network scenarios which were obtained by changing the passenger load coefficient and the number of flights. Our study demonstrates that a simple intervention, aimed at the internal reallocation of the flights on the various routes, is able to guarantee categories of users (here divided into business and non-business users) greater access to air transport services. The scenario that more than others is able to improve service efficiency, granting undeniable benefits for all users without having an impact on the costs of air carriers, particularly stands out because it: • Allows access to all network airports through direct flights; • Decongests the Rome and Milan route
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