A 0535+26: Back in business

In May/June 2005, after 10 years of inactivity, the Be/X-ray binary system A 0535+26 underwent a major X-ray outburst. In this paper data are presented from 10 years of optical, IR and X-ray monitoring showing the behaviour of the system during the quiescent epoch and the lead up to the new outburst. The results show the system going through a period when the Be star in the system had a minimal circumstellar disk and then a dramatic disk recovery leading, presumably, to the latest flare up of X-ray emission. The data are interpreted in terms of the state of the disk and its interaction with the neutron star companion.Comment: Accepted for publication in MNRA

Multiwavelength observations of the Be/X-ray binary 4U1145-619

We report optical and infrared observations of the massive X-ray binary system 4U1145-619 (V801 Cen) which show that the circumstellar disc of the Be star component is in decline. Infrared J,H,K,L magnitudes of V801Cen have been monitored from 1993 March to 1996 April. H alpha spectra have been obtained throughout the same period. We find that both the infrared excess and the Balmer emission have been in decline throughout the period of observations. A 13 year optical and X-ray history of the source has been collated, revealing a possible correlation between the optical and X-ray activity. In addition, we have used u,v,b,y,beta indices, corrected for both circumstellar and interstellar effects, to calculate the physical parameters of the underlying B star.Comment: 8 pages postscript. Accepted by MNRA

Lineage tracing and resulting phenotype of haemopoietic-derived cells in the pancreas during beta cell regeneration

Aims Transplantation of bone marrow-derived haemopoietic stem cells following streptozotocin (STZ) treatment to induce pancreatic beta cell loss in mice causes the partial regeneration of beta cell mass, with many haemopoietic cells demonstrating endothelial cell markers. This study used genetically tagged haemopoietic lineage-derived cells to determine how endogenous cells are mobilised following beta cell loss and subsequent replacement. Methods A double transgenic mouse model, Vav-iCre; R26R-enhanced yellow fluorescent protein (YFP), was used where only haemopoietic lineage cells expressed the Vavl gene promoter allowing expression of the YFP reporter gene. Between postnatal days 2 and 4 mice were injected with STZ or vehicle (control) and body weight and glycaemia were monitored. Mice were killed between days 10 and 130, and the pancreases were examined by immunofluorescence microscopy. Results YFP-expressing cells infiltrated the pancreas at all ages, being present around newly forming islets at the pancreatic ducts, and within larger islets. Small numbers of YFP-positive cells (\u3c5%) co-stained for the macrophage markers F4/80 or Mac1, for cytokeratin 19, or for the transcription factor pancreatic and duodenal homeobox 1 (PDX-1), but no co-localisation was seen with insulin or other endocrine hormones. Within islets approximately 30% of YFP-positive cells co-stained for the endothelial cell marker CD31, and following STZ the number of haemopoietic-derived cells, and the proportion that were CD31-positive, both significantly increased after 21 and 40 days, coincident with a partial replacement of beta cells. Conclusions Our results suggest that following beta cell loss endogenous haemopoietic-lineage cells contribute to intra-islet angiogenesis, which supports a partial recovery of beta cell mass. © Springer-Verlag 2010

The Be/X-ray binary LS 992/RX J0812.4-3114: physical parameters and long-term variability

We present the first long-term optical and infrared study of the optical counterpart to the source RX J0812.4-3114, an X-ray pulsar with a Be type companion. During the period covered by the observations the profile of some Balmer lines changed from absorption to emission and back again to absorption. Contemporaneously, the infrared magnitudes varied by more than 0.8 mag. This long-term variability is interpreted as the formation and subsequent dissipation of the Be star's disc. The building up of the disc ended up in an active X-ray state characterised by regular outbursts occurring at 80 day intervals. The overall duration of the formation/dissipation of the disc is found to be < 4.3 years. Optical spectroscopic and infrared photometric observations were used to refine the spectral type of the primary (B0.2IV) and to monitor the circumstellar envelope around the Be star. UBVRI and uvby\beta photometric observations allowed the determination of the astrophysical parameters of the optical companion.Comment: 7 pages, 3 figures, accepted for publication in A&

Periodicities in the high-mass X-ray binary system RXJ0146.9+6121/LSI+61 235

The high-mass X-ray binary RX J0146.9+6121, with optical counterpart LS I+61°235 (V831 Cas), is an intriguing system on the outskirts of the open cluster NGC 663. It contains the slowest Be type X-ray pulsar known with a pulse period of around 1400 s and, primarily from the study of variation in the emission line profile of Hα, it is known to have a Be decretion disc with a one-armed density wave period of approximately 1240 d. Here we present the results of an extensive photometric campaign, supplemented with optical spectroscopy, aimed at measuring short time-scale periodicities. We find three significant periodicities in the photometric data at, in order of statistical significance, 0.34, 0.67 and 0.10 d. We give arguments to support the interpretation that the 0.34 and 0.10 d periods could be due to stellar oscillations of the B-type primary star and that the 0.67 d period is the spin period of the Be star with a spin axis inclination of 23+10−8 degrees. We measured a systemic velocity of −37.0 ± 4.3 km s−1 confirming that LS I+61°235 has a high probability of membership in the young cluster NGC 663 from which the system's age can be estimated as 20–25 Myr. From archival RXTE All Sky Monitor (ASM) data we further find ‘super’ X-ray outbursts roughly every 450 d. If these super outbursts are caused by the alignment of the compact star with the one-armed decretion disc enhancement, then the orbital period is approximately 330 d

Complicaciones tras el enclavado de Ender en las fracturas trocantéreas

—Se realizó el análisis de las complicaciones de 100 casos consecutivos de pacientes con fractura trocantérea del fémur intervenidos mediante clavos de Ender, con un seguimiento postoperatorio medio de 10 meses. Hubo 75 mujeres y 25 hombres, con una media de edad de 81 años. Según la clasificación de Jensen un 27% eran estables y un 73% inestables. Se obtuvieron un 32% de complicaciones y errores de técnica intraoperatorios, un 39% de migraciones distales, un 3% de migraciones proximales y un 11% de consolidaciones viciosas en varo. Todo ello se tradujo en un 21% de reintervenciones.The rate and type of complications following Ender nailing in a series of 100 consecutive patients with trochanteric hip fractures were analysed. There were 75 women and 25 men with a mean age of 81 years. According to Jensen classification, 27% were stable fractures and 73% unstable. There were registered 32% of intraoperative complications and technical errors, 39% of distal migration of nails, 3% of proximal migrations with perforations of the femoral head and 11% of healing malpositions in varus. The rale of reoperations was 21%