Origin of the low-mass electron pair excess in light nucleus-nucleus collisions

We report measurements of electron pair production in elementary p+p and d+p reactions at 1.25 GeV/u with the HADES spectrometer. For the first time, the electron pairs were reconstructed for n+p reactions by detecting the proton spectator from the deuteron breakup. We find that the yield of electron pairs with invariant mass Me+e- > 0.15 GeV/c2 is about an order of magnitude larger in n+p reactions as compared to p+p. A comparison to model calculations demonstrates that the production mechanism is not sufficiently described yet. The electron pair spectra measured in C+C reactions are compatible with a superposition of elementary n+p and p+p collisions, leaving little room for additional electron pair sources in such light collision systems.Comment: 11 pages, 2 figures, \usepackage{epsfig

Italian guidelines for primary headaches: 2012 revised version

The first edition of the Italian diagnostic and therapeutic guidelines for primary headaches in adults was published in J Headache Pain 2(Suppl. 1):105–190 (2001). Ten years later, the guideline committee of the Italian Society for the Study of Headaches (SISC) decided it was time to update therapeutic guidelines. A literature search was carried out on Medline database, and all articles on primary headache treatments in English, German, French and Italian published from February 2001 to December 2011 were taken into account. Only randomized controlled trials (RCT) and meta-analyses were analysed for each drug. If RCT were lacking, open studies and case series were also examined. According to the previous edition, four levels of recommendation were defined on the basis of levels of evidence, scientific strength of evidence and clinical effectiveness. Recommendations for symptomatic and prophylactic treatment of migraine and cluster headache were therefore revised with respect to previous 2001 guidelines and a section was dedicated to non-pharmacological treatment. This article reports a summary of the revised version published in extenso in an Italian version

Europäische Metrologie

PTB-Mitteilungen. Band 119 (2009), Heft 4, Seite 305 - 342. ISSN 0030-834X1.: Göbel, Ernst O.: Europäische Metrologie – Einführung 2.: Kühne, Michael und Wolfgang Schmid: EURAMET – „European Association of National Metrology Institutes“ 3.: Stenger, Jörn: Das europäische Metrologieforschungsprogramm EMRP 4.: Siegner, Uwe: Das Targetprogramm „Elektrizität und Magnetismus“ in iMERA-plus 5.: Bosse, Harald: iMERA-plus und das Targetprogramm „Dimensionelle Metrologie“ 6.: Koch, Hans: Das Targetprogramm „Metrologie für die Gesundheit“ in iMERA-plus 7.: Buck, Wolfgang: Das Targetprogramm „SI und Naturkonstanten“ im iMERA-plus-Rahmen 8.: Leitner, Arnold, Wolfgang Schmid und Leslie Pendrill: Weiterentwicklung der nationalen und regionalen metrologischen Infrastruktur in Europ

QUEST (Centre for Quantum Engineering and Space-Time Research) at the PTB

1.: Ertmer, Wolfgang and Ernst O. Göbel: Preface 2.: Pfalz, Stefan: Science in QUEST: The Quest of Science 3.: Riehle, Fritz: QUEST at the PTB 4.: Peik, Ekkehard and Andreas Bauch: More Accurate Clocks – What are They Needed for? 5.: Peik, Ekkehard and Uwe Sterr: The Development of Accurate Optical Clocks 6.: Piester, Dirk and Harald Schnatz: Novel Techniques for Remote Time and Frequency Comparisons 7.: Lisdat, Christian and Christian Tamm: Super-Stable Lasers 8.: Schmidt, Piet O., Börge Hemmerling, Birgit Brandstätter and Daniel Nigg: Quantum Logic for Precision Spectroscopy 9.: Sterr, Uwe and Fritz Riehle: Atom Interferometr

Podoportation: Foot-Based Locomotion in Virtual Reality

Virtual Reality (VR) allows for infinitely large environments. However, the physical traversable space is always limited by real-world boundaries. This discrepancy between physical and virtual dimensions renders traditional locomotion methods used in real world unfeasible. To alleviate these limitations, research proposed various artificial locomotion concepts such as teleportation, treadmills, and redirected walking. However, these concepts occupy the user's hands, require complex hardware or large physical spaces. In this paper, we contribute nine VR locomotion concepts for foot-based and hands-free locomotion, relying on the 3D position of the user's feet and the pressure applied to the sole as input modalities. We evaluate our concepts and compare them to state-of-the-art point & teleport technique in a controlled experiment with 20 participants. The results confirm the viability of our approaches for hands-free and engaging locomotion. Further, based on the findings, we contribute a wireless hardware prototype implementation