Cross-correlation of the unresolved X-ray background with faint galaxies

At the faint end of the deepest X-ray surveys, a population of X-ray luminous galaxies is seen. In this paper, we present the results of a cross-correlation between the residual, unresolved X-ray photons in a very deep X-ray survey and the positions of faint galaxies, in order to examine the importance of these objects at even fainter flux levels. We measure a significant correlation on all angular scales up to ~1 arcmin. This signal could account for a significant fraction of the unresolved X-ray background, approximately 35 per cent if the clustering is similar to optically selected galaxies. However, the angular form of the correlation is seen to be qualitatively similar to that expected for clusters of galaxies and the X-ray emission could be associated with hot gas in clusters or with QSOs within galaxy clusters rather than emission from individual faint galaxies. The relative contribution from each of these possibilities cannot be determined with the current data.Comment: 7 pages LaTeX including 9 EPS figures. Uses mn.sty. Accepted for publication by MNRA

A Study of the Relationship Between Antivirus Regressions and Label Changes

AntiVirus (AV) products use multiple components to detect malware. A component which is found in virtually all AVs is the signature-based detection engine: this component assigns a particular signature label to a malware that the AV detects. In previous analysis [1-3], we observed cases of regressions in several different AVs: i.e. cases where on a particular date a given AV detects a given malware but on a later date the same AV fails to detect the same malware. We studied this aspect further by analyzing the only externally observable behaviors from these AVs, namely whether AV engines detect a malware and what labels they assign to the detected malware. In this paper we present the results of the analysis about the relationship between the changing of the labels with which AV vendors recognize malware and the AV regressions

The discovery of very red counterparts to faint X-ray sources

We present deep K-band imaging at the positions of four very faint X-ray sources found in the UK ROSAT Deep Survey to have no optical counterpart brighter than R~23. Likely identifications are found within the ROSAT error circle in all four fields with R-K colours of between 3.2 +/- 0.4 and 6.4 +/- 0.6. From a consideration of the R-K colours and X-ray to optical luminosity ratios of the candidate identifications, we tentatively classify two of the X-ray sources as very distant (z ~ 1) clusters of galaxies, one as a narrow emission line galaxy and one as an obscured QSO.Comment: 7 pages, LaTeX, 7 figures (1 postscript file each). Uses mn.sty and epsf.sty. Accepted by MNRAS. For more information see http://www.astro.soton.ac.uk/~amn/UKdee

Nitrogenous fertilisers for cereals in different rotations. Results from 1989 trials.

Trial 78BA1 Nitrogen fertiliser requirement in alternate crop - pasture rotation. Location: Badgingarra Research Station. Trial 88B4 Effect of amount and quality of organic matter residues on response to N. Location: Badgingarra Research Station. Trial 86WH36, 86M44 Lupin/wheat rotation. Location: Wongan Hills Research Station, Carrabin Research Station. Trail 87N084, 86M39, 86ME64, 87N25, 87KA49 Pea/wheat rotation. Location: Konnongorring, Merredin Research Station, Narembeen, Newdegate Research Station, Nyabing

Nitrogenous fertiliser requirements in different cropping rotations - 1979 results

Nitrogen requirement of wheat after clover, lupins and cereal - 78C1, 78N1. Nitrogen requirement of barley after clover, lupins and cereal - 78E3. Nitrogen fertiliser requirement in alternate crop-pasture rotation. Botanical composition of Pasture blocks (Sampled 16/9/79) - 78BA1. Pasture Blocks (Sampled 3/9/79) - 78WH2

Tree-level scattering amplitudes from the amplituhedron

7 pages, 2 figures, to be published in the Journal of Physics: Conference Series. Proceedings for the "7th Young Researcher Meeting", Torino, 2016A central problem in quantum field theory is the computation of scattering amplitudes. However, traditional methods are impractical to calculate high order phenomenologically relevant observables. Building on a few decades of astonishing progress in developing non-standard computational techniques, it has been recently conjectured that amplitudes in planar N=4 super Yang-Mills are given by the volume of the (dual) amplituhedron. After providing an introduction to the subject at tree-level, we discuss a special class of differential equations obeyed by the corresponding volume forms. In particular, we show how they fix completely the amplituhedron volume for next-to-maximally helicity violating scattering amplitudes.Peer reviewe

Nitrogenous fertiliser requirements in different cropping rotations 1981 results

Nitrogen Requirement of Wheat After Clover, Lupins and Cereal – 78C1, 80BA3, 78N1. Nitrogen Requirement of Barley After Clover, Lupins and Non Legume – 78E3. Nitrogen Fertiliser Requirement in Alternate Crop-Pasture Rotation – 78BA1, 78WH2. Nitrogen Fertiliser Requirement in a Lupin - Wheat Rotation – 81LG29

Shock Geometry and Spectral Breaks in Large SEP Events

Solar energetic particle (SEP) events are traditionally classified as "impulsive" or "gradual." It is now widely accepted that in gradual SEP events, particles are accelerated at coronal mass ejection-driven (CME-driven) shocks. In many of these large SEP events, particle spectra exhibit double power law or exponential rollover features, with the break energy or rollover energy ordered as (Q/A)^α, with Q being the ion charge in e and A the ion mass in units of proton mass m_p . This Q/A dependence of the spectral breaks provides an opportunity to study the underlying acceleration mechanism. In this paper, we examine how the Q/A dependence may depend on shock geometry. Using the nonlinear guiding center theory, we show that α ~ 1/5 for a quasi-perpendicular shock. Such a weak Q/A dependence is in contrast to the quasi-parallel shock case where α can reach 2. This difference in α reflects the difference of the underlying parallel and perpendicular diffusion coefficients κ_(||) and κ ⊥. We also examine the Q/A dependence of the break energy for the most general oblique shock case. Our analysis offers a possible way to remotely examine the geometry of a CME-driven shock when it is close to the Sun, where the acceleration of particle to high energies occurs

Nitrogenous fertiliser requirements in different cropping rotations

Nitrogen requirement of wheat after clover, lupins and cereal – 78C1, 80BA3. Nitrogen requirement of barley after clover, lupins and non legume crop – 78E3. Nitrogen fertiliser requirements in a lupin-wheat rotation – 81LG29. Nitrogen fertiliser requirement in alternate crop-pasture rotation – 78BA1, 78WH2. Yield response of wheat to lupin nitrogen – 83LG66