Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Production and electromagnetic decay of hyperons: a feasibility study with HADES as a phase-0 experiment at FAIR

International audienceA feasibility study has been performed in order to investigate the performance of the HADES  detector to measure the electromagnetic decays of the hyperon resonances $\Sigma (1385)^{0}$,  $\Lambda (1405)$  and $\Lambda (1520)$  as well as the production of double strange baryon systems $\Xi ^{-}$ and $\Lambda \Lambda$ in p + p reactions at a beam kinetic energy of $4.5\,{\mathrm{GeV}}$. The existing HADES  detector will be upgraded by a new Forward Detector, which extends the detector acceptance into a range of polar angles that plays a crucial role for these investigations. The analysis of each channel is preceded by a consideration of the production cross-sections. Afterwards the expected signal count rates using a target consisting of either liquid hydrogen or polyethylene are summarized

Two-pion production in the second resonance region in π−p{\pi}^-p collisions with the High-Acceptance Di-Electron Spectrometer (HADES)

Pion-induced reactions provide unique opportunities for an unambiguous description of baryonic resonances and their coupling channels by means of a partial-wave analysis. Using the secondary pion beam at SIS18, the two-pion production in the second resonance region has been investigated to unravel the role of the N(1520)32− resonance in the intermediate ρ-meson production. Results on exclusive channels with one pion (π−p) and two pions (π+π−n, π0π−p) in the final state measured in the π−-p reaction at four different pion beam momenta (0.650, 0.685, 0.733, and 0.786 GeV/c) are presented. The excitation function of the different partial waves and Δπ, Nσ, and Nρ isobar configurations is obtained, using the Bonn-Gatchina partial-wave analysis. The N(1520)32− resonance is found to dominate the Nρ final state with the branching ratio BR=12.2%±1.9%

Dilepton Production at SIS Energies Studied with HADES

One of the main goals of the HADES experiment is to achieve a detailed understanding of dielectron emission from hadronic systems at moderate bombarding energies. Results obtained on electron pair production in elementary N+N collisions pave the way to a better understanding of the origin of the pair excess seen in heavy-ion collisions. This puzzling excess, reported first by the former DLS experiment, is now being investigated systematically by HADE

Proton-number fluctuations in sNN\sqrt {s_{NN}} =2.4 GeV Au + Au collisions studied with the High-Acceptance DiElectron Spectrometer (HADES)

We present an analysis of proton-number fluctuations in sNN=2.4 GeV Au197+Au197 collisions measured with the High-Acceptance DiElectron Spectrometer (HADES) at GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt. With the help of extensive detector simulations done with Isospin Quantum Molecular Dynamics (IQMD) transport model events including nuclear clusters, various nuisance effects influencing the observed proton cumulants have been investigated. Acceptance and efficiency corrections have been applied as a function of fine-grained rapidity and transverse momentum bins, as well as considering local track density dependencies. Next, the effects of volume changes within particular centrality selections have been considered and beyond-leading-order corrections have been applied to the data. The efficiency and volume-corrected proton number moments and cumulants Kn of orders n=1, 2, 3, and 4 have been obtained as a function of centrality and phase-space bin, as well as the corresponding correlators Cn. We find that the observed correlators show a power-law scaling with the mean number of protons, i.e., Cn∝〈N〉n, indicative of mostly long-range multiparticle correlations in momentum space. We also present a comparison of our results with Au + Au collision data obtained at the Relativistic Heavy Ion Collider (RHIC) at similar centralities but higher sNN

Resonance production in p+p, p+A and A+A collisions measured with HADES

The knowledge of baryonic resonance properties and production cross sections plays an important role for the extraction and understanding of medium modifications of mesons in hot and/or dense nuclear matter. We present and discuss systematics on dielectron and strangeness production obtained with HADES on p+p, p+A and A+A collisions in the few GeV energy regime with respect to these resonances

Directed, Elliptic, and Higher Order Flow Harmonics of Protons, Deuterons, and Tritons in Au + Au Collisions at sNN\sqrt{s_{NN}} = 2.4 GeV

Flow coefficients $v_{n}$ of the orders $n = 1 - 6$ are measured with the High-Acceptance DiElectron Spectrometer (HADES) at GSI for protons, deuterons and tritons as a function of centrality, transverse momentum and rapidity in Au+Au collisions at $\sqrt{s_{NN}} = 2.4$ GeV. Combining the information from the flow coefficients of all orders allows to construct for the first time, at collision energies of a few GeV, a multi-differential picture of the angular emission pattern of these particles. It reflects the complicated interplay between the effect of the central fireball pressure on the emission of particles and their subsequent interaction with spectator matter. The high precision information on higher order flow coefficients is a major step forward in constraining the equation-of-state of dense baryonic matter.Comment: 6 pages, 5 figures; Figs. 2, 3 and 5 updated from re-analysis of data including UrQMD model predictions. Plotting error in Fig. 4 corrected; Accepted for publication in Phys. Rev. Let

Probing dense baryon-rich matter with virtual photons

International audienceAbout 10 μs after the Big Bang, the universe was filled—in addition to photons and leptons—with strong-interaction matter consisting of quarks and gluons, which transitioned to hadrons at temperatures close to kT = 150 MeV and densities several times higher than those found in nuclei. This quantum chromodynamics (QCD) matter can be created in the laboratory as a transient state by colliding heavy ions at relativistic energies. The different phases in which QCD matter may exist depend for example on temperature, pressure or baryochemical potential, and can be probed by studying the emission of electromagnetic radiation. Electron–positron pairs emerge from the decay of virtual photons, which immediately decouple from the strong interaction, and thus provide information about the properties of QCD matter at various stages. Here, we report the observation of virtual photon emission from baryon-rich QCD matter. The spectral distribution of the electron–positron pairs is nearly exponential, providing evidence for a source of temperature in excess of 70 MeV with constituents whose properties have been modified, thus reflecting peculiarities of strong-interaction QCD matter. Its bulk properties are similar to the dense matter formed in the final state of a neutron star merger, as apparent from recent multimessenger observation