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

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' attractiveness to students: The Darwinism effect

AbstractDue to significant government cuts to Higher Education funding in Southern European systems, their already underfunded universities were forced to increasingly compete for students as sources of additional revenue. Concurrently, families and students that continued to afford participation in Higher Education became more selective when choosing a university, realising the riskier investment that Higher Education participation had become. Through a competing destinations model and relying on all Italian private and public universities, this study finds that the competition forces characterising universities' attractiveness over the last decade have changed since the financial crisis of 2008. In a context of lower demand for Higher Education, the competition for students grew and universities in close proximity were better prepared to face the new challenges, leading to the growth of Higher Education clusters

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 effect of carbon nanofibers surface properties in hydrogenation and dehydrogenation reactions

In this study, carbon nanofiber-supported Pd nanoparticles were used in the hydrogenation of cinnamaldehyde and in the dehydrogenation of cinnamyl alcohol. The different graphitisation of the surface of the nanofibers and the amount of oxygen functionalisation significantly affected both activity and selectivity to the various reaction products. In particular, a decrease in nanoparticle dimensions and oxygen content resulted in an increase in overall activity for both of the studied reactions. Moreover, the selectivity to hydrocinnamaldehyde enhanced with increasing surface oxygen content in the cinnamaldehyde hydrogenation, while the selectivity to cinnamaldehyde was higher with low-functionalised nanofibers in the cinnamyl alcohol dehydrogenation. Finally, the most active catalyst proved also to be stable in consecutive runs

Enhanced features of Dictyoglomus turgidum Cellulase A engineered with carbohydrate binding module 11 from Clostridium thermocellum

Abstract Lignocellulosic biomass (LCB) is a low-cost and abundant source of fermentable sugars. Enzymatic hydrolysis is one of the main ways to obtain sugars from biomass, but most of the polysaccharide-degrading enzymes are poorly efficient on LCB and cellulases with higher performances are required. In this study, we designed a chimeric protein by adding the carbohydrate binding module (CBM) of the cellulosomal enzyme CtLic26A-Cel5E (endoglucanase H or CelH) from Clostridium (Ruminiclostridium) thermocellum to the C-terminus of Dtur CelA, an interesting hyperthermostable endoglucanase from Dictyoglomus turgidum. The activity and binding rate of both native and chimeric enzyme were evaluated on soluble and insoluble polysaccharides. The addition of a CBM resulted in a cellulase with enhanced stability at extreme pHs, higher affinity and activity on insoluble cellulose

High-resolution remote thermography using luminescent low-dimensional tin-halide perovskites

While metal-halide perovskites have recently revolutionized research in optoelectronics through a unique combination of performance and synthetic simplicity, their low-dimensional counterparts can further expand the field with hitherto unknown and practically useful optical functionalities. In this context, we present the strong temperature dependence of the photoluminescence (PL) lifetime of low-dimensional, perovskite-like tin-halides, and apply this property to thermal imaging with a high precision of 0.05 {\deg}C. The PL lifetimes are governed by the heat-assisted de-trapping of self-trapped excitons, and their values can be varied over several orders of magnitude by adjusting the temperature (up to 20 ns {\deg}C-1). Typically, this sensitive range spans up to one hundred centigrade, and it is both compound-specific and shown to be compositionally and structurally tunable from -100 to 110 {\deg} C going from [C(NH2)3]2SnBr4 to Cs4SnBr6 and (C4N2H14I)4SnI6. Finally, through the innovative implementation of cost-effective hardware for fluorescence lifetime imaging (FLI), based on time-of-flight (ToF) technology, these novel thermoluminophores have been used to record thermographic videos with high spatial and thermal resolution.Comment: 25 pages, 4 figure