361 research outputs found
A theory of stochastic integration for bond markets
We introduce a theory of stochastic integration with respect to a family of
semimartingales depending on a continuous parameter, as a mathematical
background to the theory of bond markets. We apply our results to the problem
of super-replication and utility maximization from terminal wealth in a bond
market. Finally, we compare our approach to those already existing in
literature.Comment: Published at http://dx.doi.org/10.1214/105051605000000548 in the
Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute
of Mathematical Statistics (http://www.imstat.org
Raised crosswalks efficacy on the lowering of vehicle speeds
A road hump, or speed hump, is a traffic calming device used to reduce vehicle speed and volume on residential streets. Road humps are placed across the road to slow traffic and are often installed in a series of several humps in order to prevent cars from speeding before and after the hump. Speed humps are used in locations where very low speeds are desired and reasonable. Speed humps are typically placed on residential roads and are not used on major roads, bus routes, or primary emergency response routes. In Italy, the road humps are often built in shape of raised crosswalks, or RCWs, and they are generally placed both close and between intersections.
This paper deals with the analysis of observed data on a large sample of RCWs located in Tuscany, central Italy. Such data were referred both to geometry characteristics of the single raised crosswalk and recorded differences in vehicle speeds before and after it. Speed data were gathered using two automatic radar-recorders for each one of the sampled raised crosswalks.
All the collected data were analyzed trough statistical tests in order to assess their homogeneity or not between different locations and various types of roads. Finally, we were able of making some conclusions and highlighting design aspects. On one side, RCWs with similar geometries and higher heights (about 15 cm) have similar effects on vehicle speeds lowering, regardless of local conditions (location, road geometry, driver behaviour, etc.).
Moreover, raised crosswalks installed in a series have strong efficacy than the isolated ones. On the opposite side, the effects of raised crosswalks with smaller heights (less than 6 cm) show clearly a very low influence on vehicle speed variations
Car-sharing relocation strategies: a state of the art
Traditional car sharing systems are round-trip and require advance reservations. The advances of ICT and vehicle automation allow to improve car sharing sys-tems and to provide users with greater flexibility. As it concerns reservation, new car sharing systems offer users open-ended reservation and/or instant access. As it concerns the trip typology, new car sharing systems are multiple station shared vehicle systems (MSSVS). Roundtrips still occur in this type of system, however there is a large number of one-way trips made between the multiple stations. Operating an MSSVS is much more difficult than operating a round-trip shared vehicle systems. The problem is that the system can quickly become imbalanced with respect to the number of vehicles at the multiple stations. These systems are called new (or second) generation car sharing systems. Third generation systems are the last being developed; in these systems vehicles can be accessed at any point of the area. An overview of all these car sharing systems is provided in this paper
The Development of Deep and Short Sea Shipping Container Routes Departing from Italian Ports
In this paper, an analysis of the development of Deep Sea Shipping (DSS) and Short Sea Shipping (SSS) container routes calling at Italian ports, is carried out. Data about DSS routes have been collected in the years: 2011, 2014, 2018 and 2019, while data about SSS services have been collected in 2010 and 2018. Italian ports have been classified as follows: Ligurian multi-port gateway cluster, which is formed by Leghorn, La Spezia, Genoa, Savona/Vado Ligure; Northern Adriatic multi-port gateway cluster, made up of Ancona, Ravenna, Venice and Trieste; Campanian multi-port gateway cluster, composed of Naples and Salerno; hub ports, i.e. Gioia Tauro, Cagliari (only until 2018) and Taranto (only until 2014). The most important gateway cluster, for both DSS and SSS services, is the Ligurian one which includes Genoa which is by far the major Italian container gateway port. Genoa has shown an almost constant increase in container traffic in the time period analyzed. Italian hub ports are also an important group, but they have registered a negative trend in the years under analysis. DSS routes, to Far East and the American Continent, usually call at the Ligurian ports and the hub port of Gioia Tauro. Northern Adriatic ports are crossed by only a few DSS routes, but they are crossed by a large number of SSS routes, especially feeder ones, with transshipment mainly in the hub ports of Gioia Tauro, Marsaxlokk, Piraeus and Port Said. The evolution of DSS services shows clearly the effects of naval gigantism phenomenon: the number of DSS services has decreased, but the total and, especially, the average DWT have increased. As regards SSS routes, also their frequencies have decreased, but their length and, in particular, the number of ports called, have increased: this choice is performed by container operators in order to increase the ships ’load factor’
Railway lines across the alps: Analysis of their usage through a new railway link cost function
In this paper, the usage of railway lines across the Alps is evaluated, both at present and after the new lines and base tunnels will be in operation. The railway network of a large part of Europe has been modelled through a graph, and the best routes between some of the most important origin/destination pairs in Italy and Europe have been determined. A new cost function has been developed for the links of the network. The proposed cost function is an improvement of those existing in the literature, because all cost components are taken into account in detail, while the traction cost and the number of locomotives utilized explicitly depend on the geometrical characteristics of rail lines. This last aspect is crucial in analyzing the rail lines across the Alps, as they are often operated in double or triple traction. The results of the study show the importance of new Alpine rail lines and base tunnels: the Ceneri base tunnel will remove a bottleneck on the Gotthard line, while the Brenner and Frejus base tunnels will take up a quota of demand currently served by other lines. Moreover, the new Alpine lines will create an east-west rail connection, through the Italian Padan Plain, alternative to the rail route which currently bypasses the Alps to the north
Design-based mapping for finite populations of marked points
The estimation of marks for a finite population of points scattered onto a study region is considered when a sample of these points is selected by a probabilistic sampling scheme. At each point, the mark is estimated by means of an inverse distance weighting interpolator. The design-based asymptotic properties of the resulting maps are derived when the study area remains fixed, a sequence of nested populations with increasing size is considered and samples of increasing size are selected. Conditions ensuring design-based asymptotic unbiasedness and consistency are given. They essentially require that marks are the values of a pointwise or uniformly continuous deterministic function, the enlargement of the populations is rather regular and the sequence of sampling designs ensures an asymptotic spatial balance. A computationally simple mean squared error estimator is proposed. A simulation study is performed to assess the theoretical results on artificial populations. Finally, an application for mapping the values of the height of trees in a forest stand located in North Italy is reported
Mobility Impacts of the Second Phase of Covid-19: General Considerations and Regulation from Tuscany (Italy) and Kentucky (USA)
he second phase of the virus Covid-19 is about to start a new configuration of accessibility to activities and cities. This phase, which will be able to see different restriction levels both between different countries and between successive periods, is the great challenge that the whole world is facing and which, if not managed in a planned and strategic way, risks turning into a further catastrophe. The social distancing rules imposed will necessarily lead to an escape from public transport in the cities, which could turn into total congestion of city traffic, leading the cities themselves to paralysis. We need a series of countermeasures that define new mobility capable of mitigating the effects of the mobility offer imbalance by intervening quickly, economically, and, in the short term, emergency on the whole transport chain. This article presents some possible actions to be put in place, and some mobility measures actually applied in Tuscany coastal area. © 2020, Springer Nature Switzerland AG
One world, one health, one virology of the mysterious labyrinth of Coronaviruses: the canine coronavirus affair
The described pictures underline the ability of CoVs of driving genetic evolution, to undergoes recombination, and to easy cross interspecies barriers. This potential high genetic recombination ability ensures the proliferation of new strains that may have selective advantages over parental genomes.9 In this aspect, the newly identified CCoV-Hupn-2018 should lead researchers to pay a special attention to the mechanisms of recombination among CoVs, in addition to the onset of variants as a result of mutations. Continuous monitoring of these viruses are required because (without saying as Cassandra…!!!) recombination observed in CCoVs may represent a dramatic warning for SARS-CoV-2
The knotty biology of canine coronavirus: a worrying model of coronaviruses’ danger.
Severe clinical diseases associated to αCoronavirus (αCoV) infections were recently demonstrated for the first
time in humans and a closely related but distinct canine CoV (CCoV) variant was identified in the nasopharyngeal
swabs of children with pneumonia hospitalized in Malaysia, in 2017–2018. The complete genome sequence
analysis demonstrated that the isolated strain, CCoV-HuPn-2018, was a novel canine-feline-like recombinant virus
with a unique nucleoprotein. The occurrence of three human epidemics/pandemic caused by CoVs in the recent
years and the detection of CCoV-HuPn-2018, raises questions about the ability of these viruses to overcome
species barriers from their reservoirs jumping to humans. Interestingly, in this perspective, it is interesting to
consider the report concerning new CCoV strains with a potential dual recombinant origin through partial S-gene
exchange with porcine transmissible gastroenteritis virus (TGEV) identified in pups died with acute gastroenteritis in 2009. The significance of the ability of CCoVs to evolve is still unclear, but several questions arisen on
the biology of these viruses, focusing important epidemiological outcomes in the field, in terms of both virus
evolution and prophylaxis. The new CCoV-Hupn-2018 should lead researchers to pay more attention to the
mechanisms of recombination among CoVs, rather than to the onset of variants as a result of mutations, suggesting a continuous monitoring of these viruses and in particular of SARS-CoV-
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