Hard Processes in Electron-Proton Scattering

This report summarizes some of the recent HERA results obtained by studying hard processes in ep-scattering. By resolving the structure of the proton, hard ep-reactions provide information on the parton content of the proton and may give insight into the dynamics of the exchanged parton cascade. In addition, their study offers the possibility to test the Standard Model, in particular perturbative Quantum Chromodynamics, on which the theoretical predictions on ep-scattering cross sections are generally based. Any observed deviation between the data and existing theoretical models would either indicate the need to calculate higher order contributions or hint at signs of new physics.Comment: 15 pages, 8 figures, talk given at 23rd International Conference on Physics in Collision (PIC 2003), Zeuthen, Germany, 26-28 Jun 200

Mixed Valence Europium Nitridosilicate Eu2SiN3

The mixed valence europium nitridosilicate Eu2SiN3 has been synthesized at 900°C in welded tantalum ampules starting from europium and silicon diimide Si(NH)2 in a lithium flux. The structure of the black material has been determined by single-crystal X-ray diffraction analysis (Cmca (no. 64), a=542.3(11) pm, b=1061.0(2) pm, c=1162.9(2) pm, Z=8, 767 independent reflections, 37 parameters, R1=0.017, wR2=0.032). Eu2SiN3 is a chain-type silicate comprising one-dimensional infinite nonbranched zweier chains of corner-sharing SiN4 tetrahedra running parallel [100] with a maximum stretching factor fs=1.0. The compound is isostructural with Ca2PN3 and Rb2TiO3, and it represents the first example of a nonbranched chain silicate in the class of nitridosilicates. There are two crystallographically distinct europium sites (at two different Wyckoff positions 8f) being occupied with Eu2+ and Eu3+, respectively. 151Eu Mössbauer spectroscopy of Eu2SiN3 differentiates unequivocally these two europium atoms and confirms their equiatomic multiplicity, showing static mixed valence with a constant ratio of the Eu2+ and Eu3+ signals over the whole temperature range. The Eu2+ site shows magnetic hyperfine field splitting at 4.2 K. Magnetic susceptibility measurements exhibit Curie-Weiss behavior above 24 K with an effective magnetic moment of 7.5 μB/f.u. and a small contribution of Eu3+, in accordance with Eu2+ and Eu3+ in equiatomic ratio. Ferromagnetic ordering at unusually high temperature is detected at TC=24 K. DFT calculations of Eu2SiN3 reveal a band gap of ∼0.2 eV, which is in agreement with the black color of the compound. Both DFT calculations and lattice energetic calculations (MAPLE) corroborate the assignment of two crystallographically independent Eu sites to Eu2+ and Eu3+

Human Papillomaviruses in Buschke-Lowenstein Tumors: Physical State of the DNA and Identification of a Tandem Duplication in the Noncoding Region of a Human Papillomavirus 6 Subtype

Six Buschke-Löwenstein tumors, i.e., highly differentiated squamous cell tumors of the genital region, were shown to contain human papillomavirus 6 (HPV 6) or HPV 11 genomes. The viral DNA was found in an episomal state, including a very small fraction of circular oligomers. HPV 6a and HPV 6d genomes were cloned from two of the tumors. Comparison with HPV 6b, cloned from a benign genital wart (E. -M. de Villiers, L. Gissmann, and H. zur Hausen, J. Virol. 40:932-935, 1981) by restriction mapping and partial sequence analysis, revealed a very high degree of homology with the different HPV 6 subtypes. A tandem duplication of 459 base pairs within the noncoding region of the genome was found in the new subtype HPV 6d. This structural rearrangement in a region containing the putative control elements for early gene transcription might influence the biological potential of that virus. No evidence for rearrangement of this region was found in the HPV DNA from the five other tumors

Density Functional Study of Calcium Nitride

The high-pressure behavior of Ca3N2 is studied up 100 GPa using density functional theory. Evaluation of many hypothetical polymorphs of composition A3X2 leads us to propose four high-pressure polymorphs for both α- and β-Ca3N2: (1) an anti-Rh2O3−II structure at 5 GPa, (2) an anti-B-sesquioxide structure at 10 GPa, (3) an anti-A-sesquioxide structure at 27 GPa, and (4) a hitherto unknown hexagonal structure (P63/mmc), derived from the post-perovskite structure of CaIrO3, at 38 GPa. The development of the density and bulk modulus under pressure has been examined

Surgery of the nasal septum and turbinates

The following article presents nasal septum and turbinate surgery. First an overview with special consideration of the anatomical and physiological background is given followed by indications for surgical procedures. Key steps of the gold standard procedure first described by Cottle and common variations are presented. Furthermore, some techniques dealing with special problems of the septumplasty are discussed followed by an overview on complications and long term results. However, it should be mentioned that studies on surgical procedures of the nasal septum are still not sufficient as higher evidence levels are very rare. Within a separated chapter techniques for closure of septum perforations are presented and indications particularly in the background of the standard procedure of bridge flaps forwarded by Schultz-Coulon are discussed. The second part focusses on turbinate surgery. Accordingly, anatomical and physiological basics are presented followed by indications for surgical procedures and the surgical steps of different procedures as well as postsurgical treatment and long term results

The Mu3e Data Acquisition

The Mu3e experiment aims to find or exclude the lepton flavor violating decay μ+→e+e−e+ with a sensitivity of one in 10 16 muon decays. The first phase of the experiment is currently under construction at the Paul Scherrer Institute (PSI, Switzerland), where beams with up to 10 8 muons per second are available. The detector will consist of an ultra-thin pixel tracker made from High-Voltage Monolithic Active Pixel Sensors (HV-MAPS) , complemented by scintillating tiles and fibers for precise timing measurements. The experiment produces about 100Gbit/s of zero-suppressed data, which are transported to a filter farm using a network of field programmable gate arrays (FPGAs) and fast optical links. On the filter farm, tracks and three-particle vertices are reconstructed using highly parallel algorithms running on graphics processing units, leading to a reduction of the data to 100 Mbyte/s for mass storage and offline analysis. This article introduces the system design and hardware implementation of the Mu3e data acquisition and filter farm

Commissioning of the ATLAS Level-1 Trigger with Cosmic Rays

The ATLAS detector at CERN's Large Hadron Collider will be exposed to proton-proton collisions from beams crossing at 40 MHz. A three-level trigger system was designed to select potentially interesting events and reduce the incoming rate to 100-200 Hz. The first trigger level (LVL1) is implemented in custom-built electronics, the second and third trigger levels are realized in software. Based on calorimeter information and hits in dedicated muon-trigger detectors, the LVL1 decision is made by the central-trigger processor yielding an output rate of less than 100 kHz. The allowed latency for the trigger decision at this stage is less than 2.5 microseconds. Installation of the final LVL1 trigger system at the ATLAS site is in full swing, to be completed later this year. We present a status report of the main components of the first-level trigger and the in-situ commissioning of the full trigger chain with cosmic-ray muons.Comment: On behalf of the ATLAS TDAQ Level-1 Trigger Group. Proceedings for 2007 Europhysics Conference on High Energy Physics, Manchester, July 200