Australian water mass variations from GRACE data linked to Indo-Pacific climate variability

Time-variable gravity data from the Gravity Recovery And Climate Experiment (GRACE) mission are used to study total water content over Australia for the period 2002–2010. A time-varying annual signal explains 61% of the variance of the data, in good agreement with two independent estimates of the same quantity from hydrological models. Water mass content variations across Australia are linked to Pacific and Indian Ocean variability, associated with El Niño-Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD), respectively. From 1989, positive (negative) IOD phases were related to anomalously low (high) precipitation in southeastern Australia, associated with a reduced (enhanced) tropical moisture flux. In particular, the sustained water mass content reduction over central and southern regions of Australia during the period 2006–2008 is associated with three consecutive positive IOD events.

The masses of the neutron and donor star in the high-mass X-ray binary IGR J18027-2016

Aims. We report near-infrared observations of the supergiant donor to the eclipsing high mass X-ray binary pulsar IGR J18027-2016. We aim to determine its spectral type and measure its radial velocity curve and hence determine the stellar masses of the components. Methods. ESO/VLT observations of the donor utilising the NIR spectrograph ISAAC were obtained in the H and K bands. The multi-epoch H band spectra were cross-correlated with RV templates in order to determine a radial solution for the system. Results. The spectral type of the donor was confirmed as B0-1 I. The radial velocity curve constructed has a semi-amplitude of 23.8 ± 3.1 km s-1. Combined with other measured system parameters, a dynamically determined neutron star mass of 1.4  ±  0.2–1.6  ±  0.3 M⊙ is found. The mass range of the B0-B1 I donor was 18.6  ±  0.8–21.8  ±  2.4 M⊙. These lower and upper limits were obtained under the assumption that the system is viewed edge-on (i = 90° with β = 0.89) for the lower limit and the donor fills its Roche lobe (β = 1 with i = 73.1°) for the upper limit respectively.

The supergiant B[e] star LHA 115-S 18 - binary and/or luminous blue variable?

Context. The mechanism by which supergiant (sg)B[e] stars support cool, dense dusty discs/tori and their physical relationship with other evolved, massive stars such as luminous blue variables is uncertain. Aims. In order to investigate both issues we have analysed the long term behaviour of the canonical sgB[e] star LHA 115-S 18. Methods. We employed the OGLE II-IV lightcurve to search for (a-)periodic variability and supplemented these data with new and historic spectroscopy. Results. In contrast to historical expectations for sgB[e] stars, S18 is both photometrically and spectroscopically highly variable. The lightcurve is characterised by rapid aperiodic ` aring' throughout the 16 years of observations. Changes in the high excitation emission line component of the spectrum imply evolution in the stellar temperature - as expected for luminous blue variables - although somewhat surprisingly, spectroscopic and photometric variability appears not to be correlated. Characterised by emission in low excitation metallic species, the cool circumstellar torus appears largely unaffected by this behaviour. Finally, in conjunction with intense, highly variable He ii emission, X-ray emission implies the presence of an unseen binary companion. Conclusions. S18 provides observational support for the putative physical association of (a subset of) sgB[e] stars and luminous blue variables. Given the nature of the circumstellar environment of S18 and that luminous blue variables have been suggested as SN progenitors, it is tempting to draw a parallel to the progenitors of SN1987A and SN2009ip. Moreover the likely binary nature of S18 strengthens the possibility that the dusty discs/tori that characterise sgB[e] stars are the result of binary-driven mass-loss; consequently such stars may provide a window on the short lived phase of mass-transfer in massive compact binaries.

Ferredoxin-dependent glutamate synthase: involvement in ammonium assimilation in Haloferax mediterranei

Glutamate synthase (GOGAT) is one of the two important enzymes involved in the ammonium assimilation pathway glutamine synthetase (GS)/GOGAT, which enables Hfx. mediterranei to thrive in media with low ammonium concentration or containing just nitrate as single nitrogen source. The gene coding for this enzyme, gltS, has been sequenced, analysed and compared with other GOGATs from different organisms from the three domains of life. According to its amino acid sequence, Hfx. mediterranei GOGAT displays high homology with those from other archaeal halophilic organisms and with the bacterial alpha-like subunit. Hfx. mediterranei GOGAT and GS expression was induced under conditions of ammonium restriction. The GOGAT protein was found to be a monomer with a molecular mass of 163.78 kDa, which is consistent with that estimated by gel filtration, 198 ± 30 kDa. The enzyme is highly ferredoxin dependent: activity was only observed with one of the two different 2Fe–2S ferredoxins chromatographically isolated from Hfx. mediterranei. The enzyme also displayed typical halophilic behaviour, being fully stable, and producing maximal activity, at salt concentrations from 3 to 4 M NaCl, pH 7.5 and a temperature of 50 °C.

Memorias de licenciatura: resúmenes de las memorias de licenciatura leídas en el Departamento de Historia Contemporánea de la Universidad de Alicante

Resúmenes de las memorias: GUTIERREZ LLORET, Rosa Ana: La I República. El comportamiento político de la burguesía alicantina. Leída el 30 de noviembre de 1983. Director: Dr. D. Salvador Forner Muñoz; FERRANDEZ ALBERCA, Patrocinio: Fuentes para la historia electoral de la provincia de Alicante. La sección de Elecciones y Censo Electoral del Archivo de la Diputación Provincial de Alicante. Leída el 24 de enero de 1984. Director: Dr. Salvador Forner Muñoz; MARTINEZ MICO, M.ª Angeles: Documentación de las secciones de Contabilidad, Fomento, Quintas y Suministros del Archivo de la Diputación Provincial de Alicante. Leída el 23 de marzo de 1984. Director: Doctor Salvador Forner Muñoz; GONZALVEZ ALONSO, José Vicente: Elche 1854-1868. Demografía, Sociedad y Régimen Municipal. Leída el17 de mayo de 1984. Director: Dr. Glicerio Sánchez Recio; AMOROS SANTO, Luis: Documentación de las secciones de «Cuentas de Propios, Arbitrios y Presupuestos Municipales» y «Gobierno Civil», del Archivo de la Diputación Provincial de Alicante. Leída el 18 de mayo de 1984. Director: Dr. Salvador Forner Muñoz; DE GABRIEL POVEDA, Francisca: Fondos de la sección de Beneficencia del Archivo de la Diputación Provincial de Alicante. Leída el 18 de junio de 1984. Director: Dr. Salvador Forner Muñoz; HERNANDEZ FERRIS, Rafael: La sociedad cooperativa «El trabajo», 1880-1942. Leída el 4 de octubre de 1984. Director: Dr. Glicerio Sánchez Recio; SANTACREU SOLER, José Miguel: Moneda y municipios en la provincia de Alicante durante la guerra civil española (la crisis monetaria de 1937). Leída el 6 de noviembre de 1984. Director: Dr. Salvador Forner Muñoz.