Energy dependence of exclusive J/ψJ/\psi photoproduction off protons in ultra-peripheral p-Pb collisions at sNN\sqrt{s_{\rm{NN}}} = 5.02 TeV

The ALICE Collaboration has measured the energy dependence of exclusive photoproduction of $J/\psi$ vector mesons off proton targets in ultra-peripheral p-Pb collisions at a centre-of-mass energy per nucleon pair $\sqrt{s_{\rm NN}} = 5.02$ TeV. The e$^+$e$^-$ and $\mu^+\mu^-$ decay channels are used to measure the cross section as a function of the rapidity of the $J/\psi$ in the range $-2.5 < y < 2.7$, corresponding to an energy in the $\gamma$p centre-of-mass in the interval $40 < W_{\gamma\mathrm{p}}<550$ GeV. The measurements, which are consistent with a power law dependence of the exclusive $J/\psi$ photoproduction cross section, are compared to previous results from HERA and the LHC and to several theoretical models. They are found to be compatible with previous measurements.Comment: 25 pages, 3 captioned figures, 3 tables, authors from page 19, published version, figures at http://alice-publications.web.cern.ch/node/455

The Whys of the Grand Cameo: A Holistic Approach to Understanding the Piece, its Origins and its Context

The Grand Cameo for France is the largest cameo surviving from antiquity. Scholars have debated who is portrayed on the stone and what its scene means for centuries, often, although not always, limiting their interpretations to this narrow area and typically only discussing other causes in passing. This pattern can and should be broken, allowing the stone to be what all objects truly are: windows to the lives that that objects have lived, just as all physical things are; evidence of an experience part of the world went though, whose meanings have and continue to be part of a wider network of object-meanings. The underlying purpose of this thesis is to use the Grand Cameo to prove this point. It does so by asking why the Grand Cameo came into being using Aristotle’s four-part fragmented “Why” to widen this meaning broadly enough to expand the scope of what cause means from the vernacular use of the term to include material, formal, efficient and final causes. This allows for a sufficiently satisfactory exploration of many elements of the ancient world. This thesis comprises an introduction, five chapters, and a conclusion. The first chapter discusses the material sardonyx itself, its possible origin points and how it would have been seen and used in its time in both the India and the west. It discusses the development of trade routes through the Indian ocean and Hellenistic and Egyptian ties to the east which were later taken over by Rome, as well as the Ptolemies, who they replaced. The second chapter discusses the relationship between Rome and Egypt, how their imagery and materials were usurped, and how this connects to the cameo, a medium that became Roman. Chapter three discusses Rome’s absorption and reuse of Hellenistic kingdoms, their people and their culture to see how these influenced images of Roman Rulers in the transition from the Republic to the Julio Claudians. The fourth chapter details the nature of Julio-Claudian power in Rome, the roles the family took over, and how they made themselves essential to the state, especially in how this relates to imagery from the Grand Cameo. Finally, the fifth chapter allows for the exploration of final cause by using a process of elimination based on living number of family members to establish a coherent narrative for the stone’s scene, allowing an interpretation of message and intent. It seems most likely to be justifying the handing over of power to Emperor Claudius as intended by the heavens regardless of the plans of his relatives. A roughly chronological understanding of this stone’s role from being plucked from the ground to the imperial court is presented by assessing available material. The expansive nature of the question “Why?” allows for an explanation of the stone both broader and more satisfactory than the intentions of one emperor alone, however interesting. The Grand Cameo intersects with the highly international and interactive dynamics of the ancient world as well as specific elements therein which earlier interpretations do not allow for room to explore

Formation of freely floating sub-stellar objects via close encounters

We numerically studied close encounters between a young stellar system hosting a massive, gravitationally fragmenting disk and an intruder diskless star with the purpose to determine the evolution of fragments that have formed in the disk prior to the encounter. Numerical hydrodynamics simulations in the non-inertial frame of reference of the host star were employed to simulate the prograde and retrograde co-planar encounters. The initial configuration of the target system (star plus disk) was obtained via a separate numerical simulation featuring the gravitational collapse of a solar-mass pre-stellar core. We found that close encounters can lead to the ejection of fragments that have formed in the disk of the target prior to collision. In particular, prograde encounters are more efficient in ejecting the fragments than the retrograde encounters. The masses of ejected fragments are in the brown-dwarf mass regime. They also carry away an appreciable amount of gas in their gravitational radius of influence, implying that these objects may possess extended disks or envelopes, as also suggested by Thies et al. (2015). Close encounters can also lead to the ejection of entire spiral arms, followed by fragmentation and formation of freely-floating objects straddling the planetary mass limit. However, numerical simulations with a higher resolution are needed to confirm this finding.Comment: 12 pages, 7 figures, accepted for publication by Astronomy & Astrophysic

Virtual restoration and visualization changes through light: A review

This article belongs to the Special Issue Optical Technologies Applied to Cultural Heritage.The virtual modification of the appearance of an object using lighting technologies has become very important in recent years, since the projection of light on an object allows us to alter its appearance in a virtual and reversible way. Considering the limitation of non-contact when analysing a work of art, these optical techniques have been used in fields of restoration of cultural heritage, allowing us to visualize the work as it was conceived by its author, after a process of acquisition and treatment of the image. Furthermore, the technique of altering the appearance of objects through the projection of light has been used in projects with artistic or even educational purposes. This review has treated the main studies of light projection as a technique to alter the appearance of objects, emphasizing the calibration methods used in each study, taking into account the importance of a correct calibration between devices to carry out this technology. In addition, since the described technique consists of projecting light, and one of the applications is related to cultural heritage, those studies that carry out the design and optimization of lighting systems will be described for a correct appreciation of the works of art, without altering its state of conservationThis work has been funded by project number RTI2018-097633-A-I00 of the Ministry of Science and Innovation of Spain, entitled 'Photonic restoration applied to cultural heritage: Application to Dali's painting: Two Figures.

The early evolution of viscous and self-gravitating circumstellar disks with a dust component

The long-term evolution of a circumstellar disk starting from its formation and ending in the T Tauri phase was simulated numerically with the purpose of studying the evolution of dust in the disk with distinct values of viscous \alpha-parameter and dust fragmentation velocity v_frag. We solved numerical hydrodynamics equations in the thin-disk limit, which are modified to include a dust component consisting of two parts: sub-micron-sized dust and grown dust with a maximum radius a_r. The former is strictly coupled to the gas, while the latter interacts with the gas via friction. The conversion of small to grown dust, dust growth, and dust self-gravity are also considered. We found that the process of dust growth known for the older protoplanetary phase also holds for the embedded phase of disk evolution. The dust growth efficiency depends on the radial distance from the star - a_r is largest in the inner disk and gradually declines with radial distance. In the inner disk, a_r is limited by the dust fragmentation barrier. The process of small-to-grown dust conversion is very fast once the disk is formed. The total mass of grown dust in the disk (beyond 1 AU) reaches tens or even hundreds of Earth masses already in the embedded phase of star formation and even a greater amount of grown dust drifts in the inner, unresolved 1 AU of the disk. Dust does not usually grow to radii greater than a few cm. A notable exception are models with \alpha <= 10^{-3}, in which case a zone with reduced mass transport develops in the inner disk and dust can grow to meter-sized boulders in the inner 10 AU. Grown dust drifts inward and accumulates in the inner disk regions. This effect is most pronounced in the \alpha <= 10^{-3} models where several hundreds of Earth masses can be accumulated in a narrow region of several AU from the star by the end of embedded phase. (abridged).Comment: accepted by Astronomy & Astrophysic

Measurement of exclusive Υ photoproduction from protons in pPb collisions at √s_(NN) = 5.02 TeV

The exclusive photoproduction of Υ(nS) meson states from protons, γp → Υ(nS)p (with n=1,2,3), is studied in ultraperipheral pPb collisions at a centre-of-mass energy per nucleon pair of √s_(NN) = 5.02 TeV. The measurement is performed using the Υ(nS) → μ^+μ^− decay mode, with data collected by the CMS experiment corresponding to an integrated luminosity of 32.6nb^(−1). Differential cross sections as functions of the Υ(nS) transverse momentum squared p^2_T, and rapidity y, are presented. The Υ(1S) photoproduction cross section is extracted in the rapidity range |y| < 2.2, which corresponds to photon–proton centre-of-mass energies in the range 91 < W_(γp) < 826 GeV. The data are compared to theoretical predictions based on perturbative quantum chromodynamics and to previous measurements

Destination image analytics through traveller-generated content

The explosion of content generated by users, in parallel with the spectacular growth of social media and the proliferation of mobile devices, is causing a paradigm shift in research. Surveys or interviews are no longer necessary to obtain users' opinions, because researchers can get this information freely on social media. In the field of tourism, online travel reviews (OTRs) hosted on travel-related websites stand out. The objective of this article is to demonstrate the usefulness of OTRs to analyse the image of a tourist destination. For this, a theoretical and methodological framework is defined, as well as metrics that allow for measuring different aspects (designative, appraisive and prescriptive) of the tourist image. The model is applied to the region of Attica (Greece) through a random sample of 300,000 TripAdvisor OTRs about attractions, activities, restaurants and hotels written in English between 2013 and 2018. The results show trends, preferences, assessments, and opinions from the demand side, which can be useful for destination managers in optimising the distribution of available resources and promoting sustainability