A Multi-coloured survey of NGC 253 with XMM-Newton

There is a large body of work that has used the excellent Chandra observations of nearby galaxies with neglible low mass X-ray binary (LMXB) populations. This has culminated in a ``Universal'' X-ray luminosity function (XLF) for high mass X-ray binaries (HMXBs). However, a number of methods have been used to convert from source intensities to luminosities when creating these XLFs. We have taken advantage of the XMM-Newton observations of the nearby starbursting spiral galaxy NGC 253 to test some of these methods. We find the luminosities derived from these various methods to vary by a factor of $\sim$3. We also find the most influential factor in the conversion from intensity to luminosity to be the absorption. We therefore conclude that a more consistent approach is required for determining the true Universal XLF for HMXBs. Ideally, this would involve individual spectral fitting of each X-ray source. Certainly, the line-of-sight absorption should be determined from the observations rather than assuming Galactic absorption. We find the best approach for obtaining an XLF from low-count data to be the splitting of the X-ray sources into two or more intensity intervals, and obtaining a conversion from intensity to flux for each group from spectral modelling of the summed spectrum of that group.Comment: To appear in the proceedings of "X-rays from Nearby Galaxies", 4-7 Septembeer 2007, 4 page

The molecular cloning and characterisation of cDNA coding for the alpha subunit of the acetylcholine receptor

The published version of this article is available at Oxford Journals in Nucleic Acids Research at http://nar.oxfordjournals.org/content/10/19/5809.full.pdf+htmlA rare cDNA coding for most of the α subunit of the Torpedo nicotinic acetylcholine receptor has been cloned into bacteria. The use of a mismatched oligonucleotide primer of reverse transcriptase facilitated the design of an efficient, specific probe for recombinant bacteria. DNA sequence analysis has enabled the elucidation of a large part of the polypeptide primary sequence which is discussed in relation to its acetylcholine binding activity and the location of receptor within the plasma membrane. When used as a radioactive probe, the cloned cDNA binds specifically to a single Torpedo mRNA species of about 2350 nucleotides in length but fails to show significant cross-hybridisation with a subunit mRNA extracted from cat muscle

The Fourth-Century AD Expansion of the Graeco-Roman Settlement of Karanis (Kom Aushim) in the Northern Fayum*

The Graeco-Roman town of Karanis, founded during the Ptolemaic Period in the north-eastern Fayum in the third century bc and long thought to have been abandoned in the third century ad actually saw a substantial expansion during the fourth century AD. With the creation of an 3 extension towards the west and the expansion of the eastern part, the town grew in both directions. We argue that this expansion may be related to a sudden rise of the water level in Lake Moeris (Lake Qarun), perhaps linked to a catastrophic dam breach in the eastern part of the Fayum, and the subsequent relocation of the inhabitants of the low-lying settlements north and east of the lake

Predicting space climate change

The recent decline in the open magnetic flux of the Sun heralds the end of the Grand Solar Maximum (GSM) that has persisted throughout the space age, during which the largest‐fluence Solar Energetic Particle (SEP) events have been rare and Galactic Cosmic Ray (GCR) fluxes have been relatively low. In the absence of a predictive model of the solar dynamo, we here make analogue forecasts by studying past variations of solar activity in order to evaluate how long‐term change in space climate may influence the hazardous energetic particle environment of the Earth in the future. We predict the probable future variations in GCR flux, near‐Earth interplanetary magnetic field (IMF), sunspot number, and the probability of large SEP events, all deduced from cosmogenic isotope abundance changes following 24 GSMs in a 9300‐year record

Two Species of Hornellia (Subgenus Metaceradocus) from the Florida Keys and Belize (Amphipoda, Melphidippoidea)

Hornellia (Metaceradocus) atlanticus, a new species from Belize, related to M. occidentalis, an eastern Pacific species, is reported from the Caribbean Sea and a morphologically remote new species, M. tequestae, is described from the Florida Keys

Oxidation Behavior of a Pd_(43)Cu_(27)Ni_(10)P_(20) Bulk Metallic Glass and Foam in Dry Air

The oxidation behavior of both Pd_(43)Cu_(27)Ni_(10)P_(20) bulk metallic glass (Pd4-BMG) and its amorphous foam containing 45 pct porosity (Pd4-AF) was investigated over the temperature range of 343 K (70 °C) to 623 K (350 °C) in dry air. The results showed that virtually no oxidation occurred in the Pd4-BMG at T < 523 K (250 °C), revealing the alloy’s favorable oxidation resistance in this temperature range. In addition, the oxidation kinetics at T ≥ 523 K (250 °C) followed a parabolic-rate law, and the parabolic-rate constants (k_p values) generally increased with temperature. It was found that the oxidation k_p values of the Pd4-AF are slightly lower than those of the Pd4-BMG, indicating that the porous structure contributes to improving the overall oxidation resistance. The scale formed on the alloys was composed exclusively of CuO at T ≥ 548 K (275 °C), whose thickness gradually increased with increasing temperature. In addition, the amorphous structure remained unchanged at T ≤ 548 K (275 °C), while a triplex-phase structure developed after the oxidation at higher temperatures, consisting of Pd_2Ni_2P, Cu_3P, and Pd_3P

Four Species of Synopiidae from the Caribbean Region (Crustacea: Amphipoda)

Synopia ultramarina is redescribed from the Gulf Stream and the Florida Keys and comments are made on the tangled taxonomy in Synopia. Tiron bellairsi, originally described from Barbados, is reported from Belize, at the opposite side of the Caribbean Basin. Garosyrrhoe bigarra, a Pacific species, is also reported from Belize, but no clear subspecific differences are detected as yet between Pacific and Atlantic populations

Gammaropsis arawakia, a New Species of Marine Amphipoda (Crustacea) from Jamaica

One of the dominant amphipods in algal turf communities at Discovery Bay, Jamaica, is a new species, Gammaropsis arawakia, characterized by long peduncle of uropod 3, small coxa I, 3-articulate accessory flagellum, extremely setose gnathopod 2, one pair of dorsal teeth on urosomite I, pointed ocular lobe, and oblique upper margin of cephalic sinus for antenna 2

Gitana dominica, a New Species from the Caribbean Sea (Amphipoda: Amphilochidae)

The new species Gitana dominica is described from Dominica in the Lesser Antilles; it is the first record of the genus from the western Atlantic Ocean. The new species differs from its closest relative, Gitana calitemplado, from California, in the shorter and posteroventrally excavate coxa 1. Gitana is reviewed

New Species of Neomegamphopus from Tropical America (Crustacea: Marine Amphipoda)

Neomegamphopus hiatus is described from Venezuela and the Florida Keys, N. pachiatus and N. heardi from Pacific Panama, and N. kalanii from eastern Florida. Neomegamphopus hiatus and N. pachiatus differ from a close congener, N. roosevelti (tropical eastern Pacific), in the much larger coxa 1 of mature males, the less setose gnathopods, and the broader carpus of the first gnathopod bearing a much deeper incision defining the posterior tooth; the carpus is much shorter and stouter in N. hiatus and N. pachiatus than in N. roosevelti. Neomegamphopus heardi differs from the other species in the bifid tooth on the carpus of gnathopod I in males. Questions regarding the reclassification ofthe Isaeidae, Aoridae, and Neomegamphopidae are explored and the three families amalgamated again to their status of 1973 (except Corophiidae which is segregated)