Hybrid quantum key distribution using coherent states and photon-number-resolving detectors

We put forward a hybrid quantum key distribution protocol based on coherent states, Gaussian modulation, and photon-number-resolving (PNR) detectors, and show that it may enhance the secret key generation rate (KGR) compared to homodyne-based schemes. Improvement in the KGR may be traced back to the dependence of the two-dimensional discrete output variable on both the input quadratures, thus overcoming the limitations of the original protocol. When reverse reconciliation is considered, the scheme based on PNR detectors outperforms the homodyne one both for individual and collective attacks. In the presence of direct reconciliation, the PNR strategy is still the best one against individual attacks, but for the collective ones the homodyne-based scheme is still to be preferred as the channel transmissivity decreases.Comment: 5 pages, 5 figures. We extended our analysis to reverse reconciliation and to collective attack

Evolution of long distance students' mobility: The role of the air transport service in Italy

Introduction There is a large consensus that the amount of human capital in areas plays a crucial role for regional economic development. Previous evidence on regional economics highlight that a higher concentration of human capital is associated with more population, employment growth, income and ability to innovate (e.g., Carlino et al., 2007; Glaeser and Saiz, 2004; Glaeser, 2005). Therefore, it is crucial to identify the factors that drives differences in human capital accumulation in specific areas (e.g., Boschma at al., 2013). Among others, universities have been identified as focal institutions for the attraction of highly skilled human capital toward specific areas, being firstly responsible for the attractiveness to students from different areas. Although some recent contributions have already investigated whether universities are able to affect the distribution of human capital at a regional level (Ciriaci, 2013; Abel and Deitz, 2012), less attention has been paid to the effects that the evolution of transport infrastructures play in this respect. Due to the growth of interest in the concept and the few attempts to deal with this topic, this paper aims to investigate how the Italian higher education system and transport infrastructures co-evolve over time, mainly focusing on the impact of transports infrastructures? changes on the long distance mobility of students. In the last decade, students aiming to increase their opportunities in the labour market and enhance their social status have become more prone to move, relocating in wealthier areas, whereas, at the same time, long distance students? mobility has been facilitated by the decrease of travel costs (e.g. Ryanair, Freccia Rossa). Data and Methodology Relying on the population of 75 private and public universities in Italy over the period 2002-2012 and the changes that affected both the air transportation and the high-speed rail system we investigate the long distance mobility of first-time first-year university students (more than 300 km from their households) departing from each Italian province. Consistently with the literature on spatial interaction analyses, we investigate the effects of transport infrastructures rely on a competition destinations model (e.g., Sà et al. 2004, Cattaneo et al. 2014). Results Preliminary results suggest that long distance students? mobility has been affected by the evolution of transport infrastructures with an important impact of low cost airlines from Southern to Northern Italian regions. The change in the distribution of Italian students that has been occurred in the last years (Cattaneo et al. 2014; Long 2013) is found to be facilitated by the presence of more developed transport infrastructures, which have decreased the costs associated to long distance mobility

An Autopsy-Based Analysis of Fatal Road Traffic Collisions: How the Pattern of Injury Differs with the Type of Vehicle

In Italy, in only 2018, 3310 people died in road traffic accidents, more than in any other European country. Since the revelation of this occurrence, the authors carried out an analysis aimed at investigating if there was a difference in the injury patterns among different road users. A retrospective post-mortem study on road traffic fatalities was performed, which had been autopsied at the Institute of Forensic Medicine of Milan. First, the authors analyzed the epidemiological data of all the 1022 road traffic accidents subjected to an autopsy from 2007 to 2019. Secondly, further analysis of individual autopsy reports was carried out. For this purpose, 180 autopsies belonging to 5 different categories were analyzed: car, pedestrian, motorbike, bicycle, and truck. Seventy-six percent of road traffic fatalities were male, 54% were between 10 and 49 years of age, and 62% of the patients died before arriving at a hospital. “Multiple injuries” was the main cause of death. Traumatic brain injuries were particularly high in pedestrians and cyclists. In car, motorbike, and truck fatalities, thoracic and abdominal injuries were the most frequent. Therefore, pedestrians and cyclists had a higher prevalence for traumatic head injuries, while car, motorcycle, and truck occupants, on the other hand, had a higher prevalence for thoracic and abdominal injuries

Manage with care: the frailty of self-connections in the European airport network

AbstractThis study evaluates the attractiveness of self-hubbing in terms of the (a) symmetry of itineraries and the consequences for passengers in the case of missed flights. We compute the most attractive European origin-destination (O-D) pairs through self-connection and evaluate their robustness by estimating the expected delays relative to connecting times and the travel options available when a connection is missed.Results show that the potential of self-connecting markets is reduced when accounting for asymmetrical travel options and the consequences for travelers in the case of missed flights. In terms of frequencies, self-connecting passengers are, on average, found to have fewer alternatives to complete a given O-D pair than in the case of alliance-based connections (− 33%). Our findings moderate the confidence of past evidence on self-hubbing in light of the concrete reliability of self-connections for passengers. The itinerary choice made by passengers inevitably depends on the evaluation of travel quality attributes related to the (a) symmetry of the itineraries and the costs incurred through missed connections

Towards the continuous production of supported metal nanoparticles and their application in hydrogenation reactions

The research carried out in this thesis describes the synthesis and study of mono- and bi-metallic Au-Pd catalysts and their application in catalytic reactions, namely the nitrophenol reduction reaction and the selective hydrogenation of cinnamaldehyde. In the first part, an innovative setup was assembled for the production of supported monometallic Au and Pd and bimetallic AuPd nanoparticles in a continuous fashion. The millifluidic reactor was firstly optimised for the production of Au colloid having a smaller mean particle size and size distribution compared to the batch benchmark method. During this procedure, several operational parameters, such as reaction conditions, solution residence time and mixing, were studied. A stream of a suspended solution of the support, namely TiO2, was then integrated in the metal colloid stream in order to produce the whole supported metal nanoparticle catalyst in continuous mode. Moreover, different monometallic Au and Pd and bimetallic AuPd based catalysts were synthesised to demonstrate the applicability of the apparatus for the synthesis of various supported metal nanoparticles catalysts. Interestingly, no size-dependent alloy composition was observed during the synthesis of bimetallic AuPd catalysts in continuous, most likely due to a very fast deposition of the nanoparticles on the support surface that inhibits the Oswald ripening process responsible for metal rearrangements over time. The continuous prepared catalysts were finally tested in the model reaction of reduction of 4-nitrophenol to 4-aminophenol and showed consistently higher activity compared to that of the corresponding batch produced materials due to smaller mean nanoparticle size and uniform alloy composition. In the second section of this thesis, the relation between metal particle size and catalytic activity was studied in the 4-nitrophenol reduction to 4-aminophenol using Au catalysts with different particle size. Despite the catalytic activity being ascribed indiscriminately to surface metal atoms by previous results, the tests carried out on Au/TiO2 catalysts having mean particle size ranging from 4 nm to 30 nm showed a different behaviour. In order to isolate the active sites directly involved in the reaction, a mathematical model was applied: the Au nanoparticles were approximated to perfect hemi-icosahedrons and the number of Au atoms in vertex, edge, periphery and face positions were calculated from geometrical considerations. The rate of conversion of 4-nitrophenol was found to increase linearly with the number of peripheral and edge Au atoms in the catalyst. Finally, in the third part, bimetallic AuPd-based catalysts were employed in the selective catalytic hydrogenation of cinnamaldehyde. Several parameters were varied in order to observe changes in activity and selectivity, such as stirring speed, catalyst amount, hydrogen pressure, reaction temperature, solvent and support. After initial optimisation of the reaction conditions, such as stirring speed, catalyst amount, hydrogen pressure and reaction temperature, the effect of metal composition was studied. It was observed that a maximum in activity was reached with a Au : Pd relative molar composition of 50 : 50, while high selectivity towards the hydrogenation of the vinyl group was observed increasing the Pd concentration. The enhanced activity was attributed to a combination of ligand and ensemble effect caused by formation of bimetallic alloy, while the higher selectivity of Pd-rich catalysts was attributed to the presence of a Pd surface that favoured η4 adsorption of the substrate and therefore the hydrogenation of the C=C bond. Deactivation phenomena caused by metal leaching and particle sintering was addressed by treating the catalysts at high temperature. In addition to a higher stability, the catalysts showed an enhanced selectivity towards the hydrogenation of the vinyl bond, attributed to the formation of Pd surface segregation during the high temperature oxidation step

Universities’ responses to crises : the influence of competition and reputation on tuition fees

Author's accepted manuscript.Available from 10/11/2021.This is a post-peer-review, pre-copyedit version of an article published in Higher Education. The final authenticated version is available online at: http://dx.doi.org/10.1007/s10734-020-00622-2.acceptedVersio

The Impact of Profiling Versus Static Analysis in Precision Tuning

Approximate computing techniques, such as precision tuning, are widely recognized as key enablers for the next generation of computing systems, where computation quality metrics play an important role. In precision tuning, a trade-off between the accuracy of computations and latency (and/or energy) is established, but identifying the opportunities for applying this approximate computing technique is often challenging. In this article, we compare two different approaches - worst-case static annotation and profile-guided annotation - and their implications when used in a precision tuning framework. To ensure a fair comparison, we implement the profile-guided approach in an existing tool, TAFFO, and experimentally compare it to the original static approach used by the tool. We validate our considerations using the well-known PolyBench/C benchmark suite, and two real-world application case studies. Our findings demonstrate that the profile-guided approach, fed with reasonable profiling data, in addition to needing less expertise to employ, delivers comparable speedup and better accuracy than the static approach