A Smart Pixel Camera for future Cherenkov Telescopes

The Smart Pixel Camera is a new camera for imaging atmospheric Cherenkov telescopes, suited for a next generation of large multi-telescope ground based gamma-ray observatories. The design of the camera foresees all electronics needed to process the images to be located inside the camera body at the focal plane. The camera has a modular design and is scalable in the number of pixels. The camera electronics provides the performance needed for the next generation instruments, like short signal integration time, topological trigger and short trigger gate, and at the same time the design is optimized to minimize the cost per channel. In addition new features are implemented, like the measurement of the arrival time of light pulses in the pixels on the few hundred psec timescale. The buffered readout system of the camera allows to take images at sustained rates of O(10 kHz) with a dead-time of only about 0.8 % per kHz.Comment: 8 pages, 5 figures; to appear in the proceedings of "Towards a Network of Atmospheric Cherenkov Detectors VII", 2005, Palaiseau, Franc

Epidemiology and immunogenetic background of islet cell antibody - positive nondiabetic schoolchildren : Ulm-Frankfurt population study

Islet cell antibodies (ICAs) were determined in a large cohort of white nondiabetic schoolchildren (n = 4287) from a homogenous population in southern Germany. The prevalence of ICA levels greater than or equal to 5 Juvenile Diabetes Foundation (JDF) U was 1.05% (95% confidence interval 0.8-1.4%). Analysis of HLA-DR beta and -DQ beta alleles revealed that the specificities found to be increased in insulin-dependent (type I) diabetic subjects with the same ethnic background were also associated with ICA positivity in the nondiabetic schoolchildren. HLA-DR3 (P less than 0.01) and -DR4 (P less than 0.01) phenotypes and absence of Asp residue (P less than 0.01) at codon 57 of the HLA-DQ beta-chain were significantly increased in ICA+ compared with control subjects. High levels of ICAs, which were categorized as either greater than or equal to 17 or greater than or equal to 30 JDF U, were found to be associated with amino acids other than Asp at position 57 of the HLA-DQ beta-chain. No association of ICA level was found for HLA-DR phenotypes

AsnI: A novel class II restriction endonuclease from Arthrobacter sp., strain N-CM, recognizing 5′-AT/TAAT-3′

AbstractA new class II restriction endonuclease, AsnI, with a novel sequence specificity was isolated from the Gram-positive eubacterium Arthrobacter species, strain N-CM. AsnI recognizes the unambiguously defined palindromic hexanucleotide consisting of A- and T-residues. The novel enzyme in the presence of Mg2+ cleaves specifically both strands as indicated by the arrows. The staggered cuts generate 5′-protruding ends with single-stranded 5′-TA-3′ dinucleotide extensions. The novel enzyme may be a useful tool for cloning experiments by complementation of the few enzymes such as PstI and PvuI cutting only once in the Ampr-gene of plasmids pBR322 and pBR328

Measurement of the Longitudinal Spin Transfer to Lambda and Anti-Lambda Hyperons in Polarised Muon DIS

The longitudinal polarisation transfer from muons to lambda and anti-lambda hyperons, D_LL, has been studied in deep inelastic scattering off an unpolarised isoscalar target at the COMPASS experiment at CERN. The spin transfers to lambda and anti-lambda produced in the current fragmentation region exhibit different behaviours as a function of x and xF . The measured x and xF dependences of D^lambda_LL are compatible with zero, while D^anti-lambda_LL tends to increase with xF, reaching values of 0.4 - 0.5. The resulting average values are D^lambda_LL = -0.012 +- 0.047 +- 0.024 and D^anti-lambda_LL = 0.249 +- 0.056 +- 0.049. These results are discussed in the frame of recent model calculations.Comment: 13 pages, 7 figure

A highly specific and sensitive serological assay detects SARS‑CoV‑2 antibody levels in COVID‑19 patients that correlate with neutralization

Objective The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic challenges national health systems and the global economy. Monitoring of infection rates and seroprevalence can guide public health measures to combat the pandemic. This depends on reliable tests on active and former infections. Here, we set out to develop and validate a specific and sensitive enzyme linked immunosorbent assay (ELISA) for detection of anti SARS-CoV-2 antibody levels. Methods In our ELISA, we used SARS-CoV-2 receptor-binding domain (RBD) and a stabilized version of the spike (S) ectodomain as antigens. We assessed sera from patients infected with seasonal coronaviruses, SARS-CoV-2 and controls. We determined and monitored IgM-, IgA- and IgG-antibody responses towards these antigens. In addition, for a panel of 22 sera, virus neutralization and ELISA parameters were measured and correlated. Results The RBD-based ELISA detected SARS-CoV-2-directed antibodies, did not cross-react with seasonal coronavirus antibodies and correlated with virus neutralization (R2 = 0.89). Seroconversion started at 5 days after symptom onset and led to robust antibody levels at 10 days after symptom onset. We demonstrate high specificity (99.3%; N = 1000) and sensitivity (92% for IgA, 96% for IgG and 98% for IgM; > 10 days after PCR-proven infection; N = 53) in serum. Conclusions With the described RBD-based ELISA protocol, we provide a reliable test for seroepidemiological surveys. Due to high specificity and strong correlation with virus neutralization, the RBD ELISA holds great potential to become a preferred tool to assess thresholds of protective immunity after infection and vaccination

Circulations, fuzzy relations and semirings

Circulations are similar to flows in capacity-constrained networks, with the difference that they also observe lower bounds and, unlike flows, are not directed from a source to a sink. We give a new description of circulations in networks using a technique introduced by Kawahara; he applied the same methods to network flows. We show the power and flexibility of his approach in a new application, refining it at the same time by introducing the concept of test relations. Furthermore we will give algebraic formulations of a generic algorithm for computing a flow in a network with lower bounds and a sufficient and necessary criterion for the existence of a circulation

Detaillierte Analyse der TeV-Gammastrahlung des Pulsarwindnebels HESS J0835-455 (Vela X)

Pulsar Wind Nebulae are interstellar bubbles filled with relativistic plasma and claimed to be the most frequent sources of Tera-Electron-Volts gamma-ray sources in our Galaxy. HESS J0835-455 is the TeV counterpart of the Pulsar Wind Nebula Vela X first detected with a radio telescope. It has been observed with the High Energy Stereoscopic System (H.E.S.S.) from 2003 to 2009. H.E.S.S. is an array of four Imaging Atmospheric Cherenkov Telescopes, such instruments detecting the Cherenkov light which is generated in air showers induced by gamma-ray photons. The Cherenkov telescope technique exhibits a high background level introduced by the air showers of charged cosmic rays. Detailed studies of the properties of the H.E.S.S. background will be presented. The influence of the atmosphere on the background rates is an extraordinary problem in the analysis of the Vela X data, as the so-called OnOff (blank sky) background model is applied. A new technique is proposed to counterbalance misestimations of the background level due to fluctuations in the optical density and refraction of the atmosphere. In this work, the results of the TeV analysis of Vela X are reported. They support a leptonic scenario for the plasma inside the Pulsar Wind Nebula.Pulsarwindnebel sind interstellare Volumina, die mit einem Plasma aus relativistischen Teilchen gefüllt sind. Es wird vermutet, dass sie die häufigste Quelle von Teraelektronenvolt-Gammastrahlung in unserer Galaxie sind. HESS J0835-455 ist das TeV-Pendant des ursprünglich mit einem Radioteleskop detektierten Pulsarwindnebels Vela X. Dieser wurde mit dem High Energy Stereoscopic System (H.E.S.S.) zwischen 2003 und 2009 beobachtet. H.E.S.S. ist eine Anlage aus vier abbildenden atmosphärischen Tscherenkow-Teleskopen. Solche Teleskope detektieren Tscherenkow-Licht aus Luftschauern, welche durch die Photonen der Gammastrahlung erzeugt werden. Die Messungen mit Tscherenkow-Teleskopen enthalten einen hohen Anteil an Untergrundereignissen, die durch die Luftschauer geladener kosmischer Strahlung erzeugt werden. Eine ausführliche Studie der Eigenschaften des H.E.S.S. Untergrundes wird vorgestellt. Da der Untergrund mit dem sogenannten "OnOff"-Model abgeschätzt wird, ist der Einfluss der Atmosphäre auf die Rate der Untergrundereignisse eine wichtige Aufgabenstellung der Analyse der Beobachtungsdaten von Vela X. Eine neue Methode wird vorgeschlagen, um Fehleinschätzungen der Untergrundrate auf Grund von atmosphärischen Schwankungen in der optischen Dichte und Lichtbrechung auszugleichen. Die Ergebnisse der TeV-Datenanalyse für Vela X werden vorgestellt. Diese unterstützen die Interpretation, dass sich das Plasma des Pulsarwindnebels aus Elektronen und Positronen zusammensetzt

Model refinement using bisimulation quotients

The paper shows how to refine large-scale or even infinite transition systems so as to ensure certain desired properties. First, a given system is reduced into a smallish, finite bisimulation quotient. Second, the reduced system is refined in order to ensure a given property, using any known finite-state method. Third, the refined reduced system is expanded back into an adequate refinement of the system given initially. The proposed method is based on a Galois connection between systems and their quotients. It is applicable to various models and bisimulations and is illustrated with a few qualitative and quantitative properties