Study of Apollo water impact. Volume 2 - Dynamic response of shells of revolution during vertical impact into water - No interaction Final report

Mathematical model for predicting dynamic response of thin elastic shells of revolution during water impac

The Application of a Cylindrical-spherical Floating Ring Bearing as a Device to Control Stability of Turbogenerators

The development of a new device to control stability of turbogenerators is described. The device comprises a floating ring installed between the journal and bearing housing of a fluid film bearing. The journal and the inner surface of the ring are cylindrical while the outer surface of the ring and bearing surface are spherical providing axial location of the ring and self-alignment of the bearing. The employment of this device would lead to a consistent machine performance. System stability may be controlled by changing a number of bearing and floating ring parameters. This device also offers an additional advantage of having a very low frictional characteristic. A feasibility study was carried out to investigate the suitability of the new device to turbogenerator applications. Both theoretical analysis and experimental observations were carried out. Initial results suggest that the new floating ring device is a competitive alternative to other conventional arrangements

ARCS, The Arcminute Radio Cluster-lens Search - I. Selection Criteria and Initial Results

We present the results of an unbiased radio search for gravitational lensing events with image separations between 15 and 60 arcsec, which would be associated with clusters of galaxies with masses >10^{13-14}M_{\sun}. A parent population of 1023 extended radio sources stronger than 35 mJy with stellar optical identifications was selected using the FIRST radio catalogue at 1.4 GHz and the APM optical catalogue. The FIRST catalogue was then searched for companions to the parent sources stronger than 7 mJy and with separation in the range 15 to 60 arcsec. Higher resolution observations of the resulting 38 lens candidates were made with the VLA at 1.4 GHz and 5 GHz, and with MERLIN at 5 GHz in order to test the lens hypothesis in each case. None of our targets was found to be a gravitational lens system. These results provide the best current constraint on the lensing rate for this angular scale, but improved calculations of lensing rates from realistic simulations of the clustering of matter on the relevant scales are required before cosmologically significant constraints can be derived from this null result. We now have an efficient, tested observational strategy with which it will be possible to make an order-of-magnitude larger unbiased search in the near future.Comment: Accepted for publication in MNRAS. 12 pages, 29 included PostScript figure

The evolutionary sequence of post-starburst galaxies

© 2017 The Authors. There are multiple ways in which to select post-starburst galaxies in the literature. In this work, we present a study into how two well-used selection techniques have consequences on observable post-starburst galaxy parameters, such as colour, morphology and environment, and how this affects interpretations of their role in the galaxy duty cycle. We identify a master sample of Hδ strong (EWHδ> 3Å) post-starburst galaxies from the value-added catalogue in the seventh data release of the Sloan Digital Sky Survey (SDSS DR7) over a redshift range 0.01 -2.5Å) but one having an additional cut onEWHα (> -3Å).We examine the differences in observables and AGN fractions to see what effect the Hα cut has on the properties of post-starburst galaxies and what these differing samples can tell us about the duty cycle of post-starburst galaxies. We find that Hδ strong galaxies peak in the 'blue cloud', E+As in the 'green valley' and pure E+As in the 'red sequence'.We also find that pure E+As have a more early-type morphology and a higher fraction in denser environments compared with the Hδ strong and E+A galaxies. These results suggest that there is an evolutionary sequence in the post-starburst phase from blue discy galaxies with residual star formation to passive red early-types

Crystallization and preliminary X-ray analysis of the sporulation factor SpoIIAA in its native and phosphorylated forms

Sporulation in Bacillus begins with an asymmetric cell division producing two progeny with identical chromosomes but different developmental fates. As such, it is a simple example of cellular differentiation. The establishment of cell type is controlled by a series of alternate RNA polymerase sigma subunits. The first compartment-specific sigma factor is sigma (F), whose activity is controlled by SpoIIAB, an anti-sigma factor, and SpoIIAA, an anti-sigma factor antagonist which is phosphorylated by the kinase activity of SpoIIAB. Here, the preliminary crystallographic analysis of SpoIIAA and phosphorylated SpoIIAA from B. sphaericus in forms suitable for high-resolution structure determination are reported

Synchrotron Polarization at High Galactic Latitude

We present preliminary results from mapping the high-latitude Galactic polarization with the Effelsberg Telescope at $\lambda$21 cm. Structures on the resulting maps are mostly on the scale of several degrees. The results show detection of polarization over most of the field, at the level of tens of percent of the synchrotron emission. The evidence of more structure in Stokes Q and U rather than in $\sqrt{Q^2+U^2}$ suggests the existence of Faraday rotation.Comment: To be published in the proceedings of "The Cosmic Microwave Background and its Polarization", New Astronomy Reviews, (eds. S. Hanany and K.A. Olive

NICMOS and VLBA observations of the gravitational lens system B1933+503

NICMOS observations of the complex gravitational lens system B1933+503 reveal infrared counterparts to two of the inverted spectrum radio images. The infrared images have arc-like structures. The corresponding radio images are also detected in a VLBA map made at 1.7 GHz with a resolution of 6 mas. We fail to detect two of the four inverted radio spectrum components with the VLBA even though they are clearly visible in a MERLIN map at the same frequency at a different epoch. The absence of these two components could be due to rapid variability on a time-scale less than the time delay, or to broadening of the images during propagation of the radio waves through the ISM of the lensing galaxy to an extent that they fall below the surface brightness detectability threshold of the VLBA observations. The failure to detect the same two images with NICMOS is probably due to extinction in the ISM of the lensing galaxy.Comment: 5 pages, 4 figures, submitted to MNRA

Crystallization of the regulatory and effector domains of the key sporulation response regulator Spo0A

The key response-regulator gene of sporulation, spo0A, has been cloned from Bacillus stearothermophilus and the encoded protein purified. The DNA-binding and phospho-acceptor domains of Spo0A have been prepared by tryptic digestion of the intact protein and subsequently crystallized in forms suitable for X-ray crystallographic studies. The DNA-binding domain has been crystallized in two forms, one of which diffracts X-rays to beyond 2.5 Angstrom spacing. The crystals of the phospho-acceptor domain diffract X-rays beyond 2.0 Angstrom spacing using synchrotron radiation