Fundamental limits of repeaterless quantum communications

Quantum communications promises reliable transmission of quantum information, efficient distribution of entanglement and generation of completely secure keys. For all these tasks, we need to determine the optimal point-to-point rates that are achievable by two remote parties at the ends of a quantum channel, without restrictions on their local operations and classical communication, which can be unlimited and two-way. These two-way assisted capacities represent the ultimate rates that are reachable without quantum repeaters. Here, by constructing an upper bound based on the relative entropy of entanglement and devising a dimension-independent technique dubbed ‘teleportation stretching’, we establish these capacities for many fundamental channels, namely bosonic lossy channels, quantum-limited amplifiers, dephasing and erasure channels in arbitrary dimension. In particular, we exactly determine the fundamental rate-loss tradeoff affecting any protocol of quantum key distribution. Our findings set the limits of point-to-point quantum communications and provide precise and general benchmarks for quantum repeaters

Analisis Abnormal Return Saham pada Peristiwa Merger dan Akuisisi di Indonesia

This study aims to obtain empirical evidence related to market reactions indicated by abnormal returns around the time of the 2016-2019 merger and acquisition announcement. The population in this study are companies listed on the Indonesia Stock Exchange that have conducted mergers and acquisitions. The sampling technique uses purposive sampling, the data obtained by 12 companies, namely 3 companies do mergers and 9 companies make acquisitions. Data analysis techniques in this study were one sample test method Kolmogorv-Smirnov test, paired sample t-test test, and one sample t-test using SPSS application version 25. The results of this study showed: During the 11 days study period, there were average abnormal return negative that insignificant for 7 days and average abnormal return positive that also insignificant for 4 days around the announcement time of the company’s mergers and acquisitions. These insignificant test results prove that the market was not approved during the period before and after mergers and acquisitions

Il progetto “ceraNEApolis”: un sistema informativo cartografico delle produzioni ceramiche a Neapolis (IV a.C.-VII d.C.)

In the last few decades, urban archaeology in Naples has contributed to outline the history of the city. The discovery of a great amount of pottery gave information about the daily life of ancient Naples. It was therefore decided to draw up a thematic archaeological map of the ceramics finds to reconstruct their production and distribution from the 4th century B.C. to the 7th century A.D. The project ceraNEApolis consists of a pottery map linked to a bibliographic database, which will be made available online: a working tool for experts, useful to outline the cultural city stratification and to understand the Neapolitan archaeological sites through the material. It is useful in defining the topography of production (workshop, raw materials, and resources), distribution (communication routes, harbour, market), uses and consumption patterns (house, habitat, sacred areas, burials) in the city, even if lacking monumental evidence. It contributes to the reconstruction and analysis of the cultural and urban landscape, taking into account the geomorphological elements and the data contexts even in diachronic and transversal multi-disciplinary perspective. The analysis of some significant cases shows its validity also for potential alternative fruition. The integration of virtual reality systems is a possible extension also for the knowledge, enhancement, communication and use of cultural heritage

From the Sun to Earth: effects of the 25 August 2018 geomagnetic storm

Abstract. On 25 August 2018 the interplanetary counterpart of the 20 August 2018 coronal mass ejection (CME) hit Earth, giving rise to a strong G3 geomagnetic storm. We present a description of the whole sequence of events from the Sun to the ground as well as a detailed analysis of the observed effects on Earth's environment by using a multi-instrumental approach. We studied the ICME (interplanetary-CME) propagation in interplanetary space up to the analysis of its effects in the magnetosphere, ionosphere and at ground level. To accomplish this task, we used ground- and space-collected data, including data from CSES (China Seismo-Electric Satellite), launched on 11 February 2018. We found a direct connection between the ICME impact point on the magnetopause and the pattern of Earth's auroral electrojets. Using the Tsyganenko TS04 model prevision, we were able to correctly identify the principal magnetospheric current system activating during the different phases of the geomagnetic storm. Moreover, we analysed the space weather effects associated with the 25 August 2018 solar event in terms of the evaluation of geomagnetically induced currents (GICs) and identification of possible GPS (Global Positioning System) losses of lock. We found that, despite the strong geomagnetic storm, no loss of lock had been detected. On the contrary, the GIC hazard was found to be potentially more dangerous than other past, more powerful solar events, such as the 2015 St Patrick's Day geomagnetic storm, especially at latitudes higher than 60∘ in the European sector

What are we measuring? A critique of range of motion methods currently in use for Dupuytren's disease and recommendations for practice

Background: Range of motion is the most frequently reported measure used in practice to evaluate outcomes. A goniometer is the most reliable tool to assess range of motion yet, the lack of consistency in reporting prevents comparison between studies. The aim of this study is to identify how range of motion is currently assessed and reported in Dupuytren’s disease literature. Following analysis recommendations for practice will be made to enable consistency in future studies for comparability. This paper highlights the variation in range of motion reporting in Dupuytren’s disease. Methods: A Participants, Intervention, Comparison, Outcomes and Study design format was used for the search strategy and search terms. Surgery, needle fasciotomy or collagenase injection for primary or recurrent Dupuytren’s disease in adults were included if outcomes were monitored using range of motion to record change. A literature search was performed in May 2013 using subject heading and free-text terms to also capture electronic publications ahead of print. In total 638 publications were identified and following screening 90 articles met the inclusion criteria. Data was extracted and entered onto a spreadsheet for analysis. A thematic analysis was carried out to establish any duplication, resulting in the final range of motion measures identified. Results: Range of motion measurement lacked clarity, with goniometry reportedly used in only 43 of the 90 studies, 16 stated the use of a range of motion protocol. A total of 24 different descriptors were identified describing range of motion in the 90 studies. While some studies reported active range of motion, others reported passive or were unclear. Eight of the 24 categories were identified through thematic analysis as possibly describing the same measure, ‘lack of joint extension’ and accounted for the most frequently used. Conclusions: Published studies lacked clarity in reporting range of motion, preventing data comparison and meta-analysis. Percentage change lacks context and without access to raw data, does not allow direct comparison of baseline characteristics. A clear description of what is being measured within each study was required. It is recommended that range of motion measuring and reporting for Dupuytren’s disease requires consistency to address issues that fall into 3 main categories:- Definition of terms Protocol statement Outcome reportin

Solar Intensity X-Ray and Particle Spectrometer SIXS : Instrument Design and First Results

The Solar Intensity X-ray and particle Spectrometer (SIXS) on the BepiColombo Mercury Planetary Orbiter ("Bepi") measures the direct solar X-rays, energetic protons, and electrons that bombard, and interact with, the Hermean surface. The interactions result in X-ray fluorescence and scattering, and particle induced X-ray emission (PIXE), i.e. "glow" of the surface in X-rays. Simultaneous monitoring of the incident and emitted radiation enables derivation of the abundances of some chemical elements and scattering properties of the outermost surface layer of the planet, and it may reveal other sources of X-ray emission, due to, for example, weak aurora-like phenomena in Mercury's exosphere. Mapping of the Hermean X-ray emission is the main task of the MIXS instrument onboard BepiColombo. SIXS data will also be used for investigations of the solar X-ray corona and solar energetic particles (SEP), both in the cruise phase and the passes of the Earth, Venus and Mercury before the arrival at Mercury's orbit, and the final science phase at Mercury's orbit. These observations provide the first-ever opportunity for in-situ measurements of the propagation of SEPs, their interactions with the interplanetary magnetic field, and space weather phenomena in multiple locations throughout the inner solar system far away from the Earth, and more extensively at Mercury's orbit. In this paper we describe the scientific objectives, design and calibrations, operational principles, and scientific performance of the final SIXS instrument launched to the mission to planet Mercury onboard BepiColombo. We also provide the first analysis results of science observations with SIXS, that were made during the Near-Earth Commissioning Phase and early cruise phase operations in 2018-19, including the background X-ray sky observations and "first light" observations of the Sun with the SIXS X-ray detection system (SIXS-X), and in-situ energetic electron and proton observations with the SIXS Particle detection system (SIXS-P).Peer reviewe