Precision limits of the twin-beam multiband URSULA

URSULA is a multiband astronomical photoelectric photometer which minimizes errors introduced by the presence of the atmosphere. It operates with two identical channels, one for the star to be measured and the other for a reference star. After a technical description of the present version of the apparatus, some measurements of stellar sources of different brightness, and in different atmospheric conditions are presented. These measurements, based on observations made with the 91 cm Cassegrain telescope of the Catania Astrophysical Observatory, are used to check the photometer accuracy and compare its performance with that of standard photometers

Microscopic cluster model for the description of (18O,16O) two-neutron transfer reactions

Excitation energy spectra and absolute cross-section angular distributions were measured for the 13C(18O,16O)15C two-neutron transfer reaction at 84 MeV incident energy. Exact finite-range coupled reaction channel calculations are used to analyse the data considering both the direct two-neutron transfer and the two-step sequential mechanism. For the direct calculations, two approaches are discussed: The extreme cluster and the newly introduced microscopic cluster. The latter makes use of spectroscopic amplitudes in the centre-of-mass reference frame, derived from shell-model calculations. The results describe well the experimental cross sections

Microscopic cluster model for the description of new experimental results on the C 13 (O 18, O 16) C 15 two-neutron transfer at 84 MeV incident energy

The C13(O18,O16)C15 reaction is studied at 84 MeV incident energy. Excitation energy spectra and absolute cross-section angular distributions for the strongest transitions are measured with good energy and angular resolutions. Strong selectivity for two-neutron configurations in the states of the residual nucleus is found. The measured cross-section angular distributions are analyzed by exact finite-range coupled reaction channel calculations. The two-particle wave functions are extracted using the extreme cluster and the independent coordinate scheme with shell-model derived coupling strengths. A new approach also is introduced, the microscopic cluster, in which the spectroscopic amplitudes in the center-of-mass reference frame are derived from shell-model calculations using the Moshinsky transformation brackets. This new model is able to describe well the experimental cross section and to highlight cluster configurations in the involved wave functions

HBIM FOR THE SURVEYING, ANALYSIS AND RESTORATION OF THE SAINT JOHN THE THEOLOGIAN CATHEDRAL IN NICOSIA (CYPRUS)

Abstract. The present study illustrates the results of an interdisciplinary collaboration between the Mediterranean Laboratory of Survey and Diagnostics for Architecture (RDA) of the Department of Civil Engineering and Architecture (DICAR) of the University of Catania in Italy and the Andreas Pittas Laboratories for Art Characterisation (APAC) of the Science and Technology in Archaeology Research Center (STARC) of the Cyprus Institute in Cyprus. The research focused on the application of an H-BIM approach in the study of a Mediterranean iconic heritage asset, the St. John Cathedral of Nicosia, built in 1662 on the remains of a monastery from the 15th century. The adopted methodology has provided the framework for a dynamic investigation, constantly evolving along several dimensions: historical, geometric spatial, architectural-constructive identification and mapping of degrade, interpretation of degenerative causes and design proposals.</p

Witnessing eigenstates for quantum simulation of Hamiltonian spectra

The efficient calculation of Hamiltonian spectra, a problem often intractable on classical machines, can find application in many fields, from physics to chemistry. Here, we introduce the concept of an "eigenstate witness" and through it provide a new quantum approach which combines variational methods and phase estimation to approximate eigenvalues for both ground and excited states. This protocol is experimentally verified on a programmable silicon quantum photonic chip, a mass-manufacturable platform, which embeds entangled state generation, arbitrary controlled-unitary operations, and projective measurements. Both ground and excited states are experimentally found with fidelities >99%, and their eigenvalues are estimated with 32-bits of precision. We also investigate and discuss the scalability of the approach and study its performance through numerical simulations of more complex Hamiltonians. This result shows promising progress towards quantum chemistry on quantum computers.Comment: 9 pages, 4 figures, plus Supplementary Material [New version with minor typos corrected.

STUDY OF THE O-18+Ni-64 TWO-NEUTRON TRANSFER REACTION AT 84 MeV BY MAGNEX

A study of the two-neutron transfer reaction of the O-18 + Ni-64 system at 84 MeV incident energy to the ground and first 2(+) excited state of the residual Ni-66 nucleus is presented. The experiment was performed at the INFN-LNS (Italy) by using the large acceptance MAGNEX spectrometer. Theoretical models are used in order to disentangle the competition between long-range and short-range correlations

Long-range versus short-range correlations in the two-neutron transfer reaction Ni 64 (O 18, O 16) Ni 66

Recently, various two-neutron transfer studies using the (18O,16O) reaction were performed with a large success. This was achieved because of a combined use of the microscopic quantum description of the reaction mechanism and of the nuclear structure. In the present work we use this methodology to study the two-neutron transfer reaction of the 18O+64Ni system at 84 MeV incident energy, to the ground and first 2+ excited state of the residual 66Ni nucleus. All the experimental data were measured by the large acceptance MAGNEX spectrometer at the Instituto Nazionale di Fisica Nucleare \u2013Laboratori Nazionali del Sud (Italy). We have performed exact finite range cross section calculations using the coupled channel Born approximation (CCBA) and coupled reaction channel (CRC) method for the sequential and direct two-neutron transfers, respectively. Moreover, this is the first time that the formalism of the microscopic interaction boson model (IBM-2) was applied to a two-neutron transfer reaction. From our results we conclude that for two-neutron transfer to the ground state of 66Ni, the direct transfer is the dominant reaction mechanism, whereas for the transfer to the first excited state of 66Ni, the sequential process dominates. A competition between long-range and short-range correlations is discussed, in particular, how the use of two different models (Shell model and IBM's) help to disentangle long- and short-range correlations

Modularity map of the network of human cell differentiation

Cell differentiation in multicellular organisms is a complex process whose mechanism can be understood by a reductionist approach, in which the individual processes that control the generation of different cell types are identified. Alternatively, a large scale approach in search of different organizational features of the growth stages promises to reveal its modular global structure with the goal of discovering previously unknown relations between cell types. Here we sort and analyze a large set of scattered data to construct the network of human cell differentiation (NHCD) based on cell types (nodes) and differentiation steps (links) from the fertilized egg to a crying baby. We discover a dynamical law of critical branching, which reveals a fractal regularity in the modular organization of the network, and allows us to observe the network at different scales. The emerging picture clearly identifies clusters of cell types following a hierarchical organization, ranging from sub-modules to super-modules of specialized tissues and organs on varying scales. This discovery will allow one to treat the development of a particular cell function in the context of the complex network of human development as a whole. Our results point to an integrated large-scale view of the network of cell types systematically revealing ties between previously unrelated domains in organ functions.Comment: 32 pages, 7 figure

THE VIRTUAL BATCAVE: A PROJECT FOR THE SAFEGUARD OF A UNESCO WHL FRAGILE ECOSYSTEM

Abstract. This abstract illustrates an interdisciplinary research project which focuses on the study, conservation and enhancement, through 3D digitization and virtual fruition, of an asset of great naturalistic, historical and ethnoanthropological value: Grotta dei Pipistrelli of Pantalica Nature Reserve (Sortino, SR). The cave (located in the Calcinara necropolis) is characterized by a great beauty as well as by a high cultural relevance and a remarkable scientific importance. In 2005, it awarded the UNESCO World Heritage title for its high historic, archaeological and speleological profile. Despite the site is being studied by specialists in chiropterofauna, nowadays there is not a comprehensive and reliable documentation of the plano-altimetric morphology of the cave, able to constitute a 3D database of essential information (e.g. morphological, geological, textural and wildlife information) for current and future studies, and to preserve the memory of this fragile ecosystem. The process of 3D digitization aims to create a model of the cave that allows us to enjoy this place, to explore it and to closely understand it in order to limit the anthropic pressure caused by visitors on the real site. Consequently, it is proposed the creation of a virtual environment, as a reproduction of the real one, which can be enjoyed by all categories of users.</p

Learning Quantum Systems

Quantum technologies hold the promise to revolutionise our society with ground-breaking applications in secure communication, high-performance computing and ultra-precise sensing. One of the main features in scaling up quantum technologies is that the complexity of quantum systems scales exponentially with their size. This poses severe challenges in the efficient calibration, benchmarking and validation of quantum states and their dynamical control. While the complete simulation of large-scale quantum systems may only be possible with a quantum computer, classical characterisation and optimisation methods (supported by cutting edge numerical techniques) can still play an important role. Here, we review classical approaches to learning quantum systems, their correlation properties, their dynamics and their interaction with the environment. We discuss theoretical proposals and successful implementations in different physical platforms such as spin qubits, trapped ions, photonic and atomic systems, and superconducting circuits. This review provides a brief background for key concepts recurring across many of these approaches, such as the Bayesian formalism or Neural Networks, and outlines open questions