Experimental Satellite Quantum Communications

Quantum Communications on planetary scale require complementary channels including ground and satellite links. The former have progressed up to commercial stage using fiber-cables, while for satellite links, the absence of terminals in orbit has impaired theirs development. However, the demonstration of the feasibility of such links is crucial for designing space payloads and to eventually enable the realization of protocols such as quantum-key-distribution (QKD) and quantum teleportation along satellite-to-ground or intersatellite links. We demonstrated the faithful transmission of qubits from space to ground by exploiting satellite corner cube retroreflectors acting as transmitter in orbit, obtaining a low error rate suitable for QKD. We also propose a two-way QKD protocol exploiting modulated retroreflectors that necessitates a minimal payload on satellite, thus facilitating the expansion of Space Quantum Communications

Characterization of Sicilian olive genotypes by multivariate analysis of leaf and fruit chemical and morphological properties

Leaf and fruit size and shape were measured and mannitol, glucose, sucrose and malic acid were quantified in leaf, bark and fruit of 25 Sicilian olive genotypes. Multivariate analysis was used to individuate groups with similar chemical composition and morphological traits suggesting potential for stress tolerance and/or oil yield and quality. Mannitol content varied greatly among genotypes and was the most abundant carbohydrate in leaf and bark, whereas glucose was the most abundant in fruit. Sucrose and malic acid were generally low indicating a marginal role in olive tissues. Mannitol and glucose were directly related in both leaf and fruit tissues. Genotypes also differed for carbohydrate partitioning among tissues, and multivariate analysis individuated a group of seven genotypes associated to leaf length:width, length:area, glucose, mannitol, and sucrose, which should stand for environmental stress tolerance. Multivariate analysis also individuated a group of six genotypes associated to malic acid, oleic acid, oleic:linoleic, and polyphenols, and therefore showing potential for production of high quality and stable olive oil. Overall, three of the 25 genotypes in trial seem to combine a good degree of abiotic stress tolerance with production of high quality and stable olive oil

Sharp estimates for the anisotropic torsional rigidity and the principal frequency

In this paper we generalize some classical estimates involving the torsional rigidity and the principal frequency of a convex domain to a class of functionals related to some anisotropic non linear operators

Family firms and investments

Family firms are a widespread control structure in most countries, especially among smaller firms. A vast literature addresses the question of whether they are performing better or worse than comparable non family firms, with not entirely conclusive results. Here we take a different, indirect approach and test whether investment decisions in family firms are more sensitive to uncertainty than in other firms. By using a novel dataset that includess both a better definition of family firms than commonly used (through self evaluation) and a very good proxy of the uncertainty on future demand that firms face, we are able to verify that – as compared to other firms – family firms are significantly more sensitive to uncertainty: this might contribute to explain why in some situations they perform better, whereas in others they do worse. We find evidence that this greater sensitivity to uncertainty in family firms is basically due to the effects of risk aversion and capital irreversibility, where the latter appear to be associated to a greater opaqueness of family firms rather than to the degree of sunkness of fixed capital. Finally, we propose some evidence that the prevalence of family firms in Italy might be associated to long standing institutional factors, such as an inefficient law enforcement system and a low social capital.Family firms; investments; uncertainty; risk aversion; capital irreversibility

Interference at the Single Photon Level Along Satellite-Ground Channels

Quantum interference arising from superposition of states is a striking evidence of the validity of Quantum Mechanics, confirmed in many experiments and also exploited in applications. However, as for any scientific theory, Quantum Mechanics is valid within the limits in which it has been experimentally verified. In order to extend such limits, it is necessary to observe quantum interference in unexplored conditions such as moving terminals at large distance in Space. Here we experimentally demonstrate single photon interference at a ground station due to the coherent superposition of two temporal modes reflected by a rapidly moving satellite thousand kilometers away. The relative speed of the satellite induces a varying modulation in the interference pattern. The measurement of the satellite distance in real time by laser ranging allowed us to precisely predict the instantaneous value of the interference phase. We then observed the interference patterns with visibility up to $67\%$ with three different satellites and with path length up to 5000 km. Our results attest the viability of photon temporal modes for fundamental tests of Physics and Quantum Communications in Space.Comment: Version accepted for publication in Phys. Rev. Let

Diurnal regulation of leaf water status in high- and low-mannitol olive cultivars

The role of mannitol and malic acid in the regulation of diurnal leaf water relations was investigated in ‘Biancolilla’ (high-mannitol) and ‘Cerasuola’ (low-mannitol) olive trees. Photosynthetic photon flux density (PPFD), vapor pressure deficit (VPD), stomatal conductance (gs), transpiration rate (T), relative water content (RWC), mannitol and malic acid were measured in ‘Biancolilla’ and ‘Cerasuola’ leaves during a dry and hot day of summer in Sicily. In general, leaves of ‘Biancolilla’ trees exhibited greater mannitol content, higher gs and T, but lower RWC than leaves of ‘Cerasuola’ trees. Differences in gs and T between the two cultivars were evident mainly in mid to late morning. ‘Biancolilla’ leaves accumulated mannitol at midday and again late in the evening. Stomatal responses to VPD were RWC dependent, and limited somewhat T, only in ‘Biancolilla’. Mannitol was directly related to RWC, and may play an osmotic role, in ‘Biancolilla’ leaves, whereas ‘Cerasuola’ leaves remained well hydrated by just transpiring less and regardless of mannitol. A day-time accumulation and night-time utilization of mannitol in ‘Biancolilla’ leaves is proposed as an efficient mechanism to regulate water status and growth

Experimental single photon exchange along a space link of 7000 km

Extending the single photon transmission distance is a basic requirement for the implementation of quantum communication on a global scale. In this work we report the single photon exchange from a medium Earth orbit satellite (MEO) at more than 7000 km of slanted distance to the ground station at the Matera Laser Ranging Observatory. The single photon transmitter was realized by exploiting the corner cube retro-reflectors mounted on the LAGEOS-2 satellite. Long duration of data collection is possible with such altitude, up to 43 minutes in a single passage. The mean number of photons per pulse ({\mu}sat) has been limited to 1 for 200 seconds, resulting in an average detection rate of 3.0 cps and a signal to noise ratio of 1.5. The feasibility of single photon exchange from MEO satellites paves the way to tests of Quantum Mechanics in moving frames and to global Quantum Information.Comment: 5 pages, updated versio

Determination of a strength index for upper body local endurance strength in sedentary individuals: a cross sectional analysis

A range of balance between flexor and extensor muscles is fundamental in order to prevent pathologies caused by bad postures or to ensure health of the joint as a measure of prevention of overtraining in specific muscle groups. Therefore, the aim of this study is to examine the ratio between "pulling" and "pushing" strength in sedentary individuals. 212 healthy participants, of both genders (139 male and 73 female; age 32 \ub1 13.3 years, weight 70.2 \ub1 14.1 kg, height 173 \ub1 9 cm) were retained for investigation. Strength was assessed through a new methodology: Pulling through a lat-pulldown test while pushing strength through a chest-press test. Both tests were performed to exhaustion with an overload of 30 % of each participants bodyweight. Such method aims to prevent excessive overloads in sedentary individuals. Pearson's correlations and a t test to assess differences were analyzed. Subsequently, the ratio for both genders of pulling and pushing local endurance strength was assessed by means. A mean number of 57 repetitions was shown with the lat-pulldown while 34 repetition with the chest press. A correlation of 0.42 has been found between the number of repetitions of the two tests. A significant difference (p < 0.001) was found between such performances. No correlation was found between the strength measures and the anthropometric parameters of the participants. The lat machine to chest press ratio was 1.36:1 for male while 2.69:1 for female. The results indicate that sedentary participants have higher pulling rather than pushing local endurance strength. Such ratio should be considered as a normative value when starting to perform exercise protocols. Resistance training should be performed in order to improve strength measures of the weaker muscles and reduce such ratio