5-Acetyl-4-(2-chloro­phen­yl)-6-methyl-3,4-dihydro­pyrimidine-2(1H)-thione

In the title mol­ecule, C13H13ClN2OS, the heterocyclic ring adopts a flattened boat conformation with the plane through the four coplanar atoms making a dihedral angle of 85.6 (1)° with the benzene ring, which adopts an axial orientation. The thionyl, acetyl and methyl groups all have equatorial orientations. Inter­molecular N—H⋯O, N—H⋯S and C—H⋯S hydrogen bonds are found in the crystal structure. A weak C—H⋯π inter­action involving the benzene ring also occurs

Absolute calibration of the LOPES antenna system

Radio emission in extensive air showers arises from an interaction with the geomagnetic field and is subject of theoretical studies. This radio emission has advantages for the detection of high energy cosmic rays compared to secondary particle or fluorescence measurement methods. Radio antennas like the LOPES30 antenna system are suited to investigate this emission process by detecting the radio pulses. The characteristic observable parameters like electric field strength and pulse length require a calibration which was done with a reference radio source resulting in an amplification factor representing the system behavior in the environment of the KASCADE-Grande experiment. Knowing the amplification factor and the gain of the LOPES antennas LOPES30 is calibrated absolutely for systematic analyses of the radio emission.Comment: 5 pages, Proceedings of International Workshop on Acoustic and Radio EeV Neutrino detection Activities: ARENA, May 17-19, 2005, DESY Zeuthe

Stochastic B-series and order conditions for exponential integrators

We discuss stochastic differential equations with a stiff linear part and their approximation by stochastic exponential integrators. Representing the exact and approximate solutions using B-series and rooted trees, we derive the order conditions for stochastic exponential integrators. The resulting general order theory covers both It\^{o} and Stratonovich integration

Backward error analysis and the substitution law for Lie group integrators

Butcher series are combinatorial devices used in the study of numerical methods for differential equations evolving on vector spaces. More precisely, they are formal series developments of differential operators indexed over rooted trees, and can be used to represent a large class of numerical methods. The theory of backward error analysis for differential equations has a particularly nice description when applied to methods represented by Butcher series. For the study of differential equations evolving on more general manifolds, a generalization of Butcher series has been introduced, called Lie--Butcher series. This paper presents the theory of backward error analysis for methods based on Lie--Butcher series.Comment: Minor corrections and additions. Final versio

The Chernobyl Tissue Bank - A Repository for Biomaterial and Data Used in Integrative and Systems Biology Modeling the Human Response to Radiation

The only unequivocal radiological effect of the Chernobyl accident on human health is the increase in thyroid cancer in those exposed in childhood or early adolescence. In response to the scientific interest in studying the molecular biology of thyroid cancer post Chernobyl, the Chernobyl Tissue Bank (CTB: www.chernobyltissuebank.com) was established in 1998. Thus far it is has collected biological samples from 3,861 individuals, and provided 27 research projects with 11,254 samples. The CTB was designed from its outset as a resource to promote the integration of research and clinical data to facilitate a systems biology approach to radiation related thyroid cancer. The project has therefore developed as a multidisciplinary collaboration between clinicians, dosimetrists, molecular biologists and bioinformaticians and serves as a paradigm for tissue banking in the omics era

Variable X-ray Absorption in the Seyfert 2 Galaxy Mrk 348

We present RXTE monitoring observations of the Seyfert 2 galaxy Mrk 348 spanning a 6 month period. The time-averaged spectrum in the 3-20 keV band shows many features characteristic of a Compton-thin Seyfert 2 galaxy, namely a hard underlying power-law continuum (photon index = 1.8) with heavy soft X-ray absorption (N_h ~ 10^23 cm^-2) plus measureable iron line emission (equivalent width ~ 100 eV) and, at high energy, evidence for a reflection component (R < 1). During the first half of the monitoring period the X-ray continuum flux from Mrk 348 remained relatively steady. However this was followed by a significant brightening of the source (by roughly a factor of 4) with the fastest change corresponding to a doubling of its X-ray flux on a timescale of about 20 days. The flux increase was accompanied by a marked softening of X-ray spectrum most likely attributable to a factor 3 decline in the intrinsic line-of-sight column density. In contrast the iron line and the reflection components showed no evidence of variability. These observations suggest a scenario in which the central X-ray source is surrounded by a patchy distribution of absorbing material located within about a light-week of the nucleus of Mrk 348. The random movement of individual clouds within the absorbing screen, across our line of sight, produces substantial temporal variations in the measured column density on timescales of weeks to months and gives rise to the observed X-ray spectral variability. However, as viewed from the nucleus the global coverage and typical thickness of the cloud layer remains relatively constant.Comment: 19 pages, 3 figures Accepted for publication in the Astrophysical Journa

2-Bromo-N′-[(Z)-2-bromo­benzyl­idene]-5-methoxy­benzohydrazide

In the title compound, C15H12Br2N2O2, the mol­ecule adopts an E conformation about the C=N double bond and a transoid conformation about the central N—N bond, with a C(=O)—N—N—C(H) dihedral angle of 169.4 (4)°. In the crystal, mol­ecules are linked by N—H⋯O hydrogen bonds, leading to C(4) chains. The packing also features slipped π–π stacking inter­actions, with a centroid–centroid separation of 3.838 (3) Å and a slippage of 1.19 Å

2,3,5-Triphenyl­pyrazine

In the title mol­ecule, C22H16N2, the pyrazine ring deviates very slightly from planarity [maximum deviation 0.044 (3) Å], tending towards a twist-boat conformation. The phenyl ring at position 3 makes dihedral angles of 64.0 (2) and 45.8 (2)°, respectively, with the phenyl rings at positions 2 and 5. The dihedral angle between the phenyl rings at positions 2 and 5 is 49.7 (2)°. A C—H⋯π inter­action is found in the crystal structure, but no classical hydrogen bonds form

1-(3,5-Dimeth­oxy­phen­yl)-2-(4-fluoro­phen­yl)-4,5-dimethyl-1H-imidazole

In the title compound, C19H19FN2O2, the imidazole ring is essentially planar [maximum deviation = 0.0030 (8) Å] and makes dihedral angles of 66.45 (7) and 29.98 (7)° with the benzene rings attached to the ring N and C atoms, respectively. The dihedral angle between the two benzene rings is 64.79 (7)°. A C—H⋯π inter­action is found in the crystal structure. The two meth­oxy groups were found to be disordered over two sets of sites with occupancy factors of 0.803 (4) and 0.197 (4). The F atom is disordered over two sites with occupancy factors of 0.929 (4) and 0.071 (4)