Identification of 13 DB + dM and 2 DC + dM binaries from the Sloan Digital Sky Survey

We present the identification of 13 DB + dM binaries and 2 DC + dM binaries from the Sloan Digital Sky Survey (SDSS). Before the SDSS only 2 DB + dM binaries and 1 DC + dM binary were known. At least three, possibly 8, of the new DB + dM binaries seem to have white dwarf temperatures well above 30000 K which would place them in the so called DB-gap. Finding these DB white dwarfs in binaries may suggest that they have formed through a different evolutionary channel than the ones in which DA white dwarfs transform into DB white dwarfs due to convection in the upper layers.Comment: 4 pages, 2 figures, accepted for publication in A&A Letter

Circulation of human influenza viruses and emergence of Oseltamivir-resistant A(H1N1) viruses in Cameroon, Central Africa

<p>Abstract</p> <p>Background</p> <p>While influenza surveillance has increased in most developing countries in the last few years, little influenza surveillance has been carried out in sub-Saharan Africa and no information is available in Central Africa. The objective of this study was to assess the prevalence of influenza viruses circulating in Yaounde, Cameroon and determine their antigenic and genetic characteristics.</p> <p>Methods</p> <p>Throat and/or nasal swabs were collected from November 2007 to October 2008 from outpatients with influenza-like illness (ILI) in Yaounde, Cameroon and analyzed by two different techniques: a one-step real time reverse transcription-polymerase chain reaction (RT-PCR) and virus isolation in MDCK cells. Typing and subtyping of virus isolates was performed by hemagglutination inhibition (HI), and viruses were sent to the WHO Collaborating Centre in London, UK for further characterization and analyses of antiviral resistance by enzyme inhibition assay and nucleotide sequencing.</p> <p>Results</p> <p>A total of 238 patients with ILI were sampled. During this period 70 (29%) samples were positive for influenza by RT-PCR, of which only 26 (11%) were positive by virus isolation. By HI assay, 20 of the 26 isolates were influenza type A (10 H3N2 and 10 H1N1) and 6 were influenza type B (2 B/Victoria/2/87 lineage and 4 B/Yagamata/16/88 lineage). Seven (70%) of the H1N1 isolates were shown to be resistant to oseltamivir due to a H275Y mutation.</p> <p>Conclusions</p> <p>This study confirmed the circulation of influenza A(H1N1), A(H3N2) and B viruses in the human population in Central Africa and describes the emergence of oseltamivir-resistant A(H1N1) viruses in Central Africa.</p

Investigating the function of single-pass leucine-rich repeat transmembrane proteins in cell signalling and early neural development

Single-pass leucine-rich (LRR) repeat transmembrane proteins contain a diverse number of repeating motifs of approximately 24 amino acid residues with a large number being conserved leucines. Flrt expression is observed in the developing embryo in important developmental regions such as the central nervous system and developing skeletal muscle. Knockout of Flrt3 during embryogenesis results in early embryonic lethality making in vivo analysis of endogenous Flrt3 function difficult. No cell based model exists for studying Flrt function. Flrt family members have previously been shown to interact with FgfR1 and 2, with the Flrt1 FgfR1 interaction resulting in an increase in FgfR1 signalling activity. Immunofluorescent microscopy reveals that Flrt3 from mouse (Mus musculus) co-localises with FgfR1 both intracellularly and at the plasma membrane, with the interaction resulting in a trend of increased FgfR1 signalling being observed, and phosphorylation of tyrosine residues within Flrt3. An attempt was made to identify domains of the protein important in the trend of increased FgfR1 signalling, but no domains could be identified as contributing to this outcome. To study endogenous Flrt3 function, the P19 embryonic carcinoma retinoic acid-induced neural differentiation model was used, and the results showed a rapid and robust induction of Flrt3 mRNA and protein expression. A region of the promoter between 4 kb and 6 kb upstream of the Flrt3 start site was found to be partially responsible for the induction of Flrt3. Interestingly, this response element was not within a region of promoter that showed conservation among higher-order mammals. An effect of increased Flrt3 expression during neural differentiation was observed, resulting in decreased MAPK pathway activation. Induction of Flrt3 is found to occur prior to that of Sox1, accepted to be one of the first genes up-regulated in early neurectoderm differentiation, yet was found to be not solely responsible for the induction of Sox1. The individual cell expression of Flrt3 and Sox1 was analysed by immunofluorescence, although it did not reveal details regarding induction of Sox1 in cells with increased Flrt3 expression. The potential for a common feature of single-pass LRR transmembrane proteins to function as modulators of receptor signalling during embryonic development was investigated, using Lrrtm3 and FgfR1 as an example. Lrrtm3 was investigated as a modulator of FgfR1 signalling due to overlapping region of expression with FgfR1 in the developing embryo. Lrrtm3 was found to co-localise and form an interaction with FgfR1, with this interaction resulting in an increase in FgfR1 signalling. The data obtained in this thesis provides further insight into not only the role of the Flrt protein family as FgfR1 modulators, but potentially identifies a role for similar, if not all single-pass LRR transmembrane proteins as regulators of receptor signalling during embryonic development. While the results of Chapter 3 and 5 were obtained using a protein over-expression system, the first model for studying endogenous Flrt3 was identified and characterised in Chapter 4, providing the opportunity to study Flrt3 function during development with protein expression levels closely resembling those that are found in the embryo.Thesis (M.Phil.) -- University of Adelaide, School of Biological Sciences, 201

A ZZ Ceti white dwarf in SDSS J133941.11+484727.5

We present time-resolved spectroscopy and photometry of the cataclysmic variable (CV) SDSSJ133941.11+484727.5 (SDSS1339) which has been discovered in the Sloan Digital Sky Survey Data Release 4. The orbital period determined from radial velocity studies is 82.524(24)min, close to the observed period minimum. The optical spectrum of SDSS1339 is dominated to 90% by emission from the white dwarf. The spectrum can be successfully reproduced by a three-component model (white dwarf, disc, secondary) with Twd=12500K for a fixed log g=8.0, d=170pc, and a spectral type of the secondary later than M8. The mass transfer rate corresponding to the optical luminosity of the accretion disc is very low,~1.7x10^-13Msun/yr. Optical photometry reveals a coherent variability at 641s with an amplitude of 0.025mag, which we interpret as non-radial pulsations of the white dwarf. In addition, a long-period photometric variation with a period of either 320min or 344min and an amplitude of 0.025mag is detected, which bears no apparent relation with the orbital period of the system. Similar long-period photometric signals have been found in the CVs SDSSJ123813.73-033933.0, SDSSJ204817.85-061044.8, GW Lib and FS Aur, but so far no working model for this behaviour is available.Comment: MNRAS, in press, 8 pages, 10 figures, some figures downgraded to meet the file size constraint of arxiv.or

Global update on the susceptibility of humam influenza viruses to neuraminidase inhibitors 2012-2013

Emergence of influenza viruses with reduced susceptibility to neuraminidase inhibitors (NAIs) is sporadic, often follows exposure to NAIs, but occasionally occurs in the absence of NAI pressure. The emergence and global spread in 2007/2008 of A(H1N1) influenza viruses showing clinical resistance to oseltamivir due to neuraminidase (NA) H275Y substitution, in the absence of drug pressure, warrants continued vigilance and monitoring for similar viruses. Four World Health Organization (WHO) Collaborating Centres for Reference and Research on Influenza and one WHO Collaborating Centre for the Surveillance, Epidemiology and Control of Influenza (WHO CCs) tested 11,387 viruses collected by WHO-recognized National Influenza Centres (NIC) between May 2012 and May 2013 to determine 50% inhibitory concentration (IC50) data for oseltamivir, zanamivir, peramivir and laninamivir. The data were evaluated using normalized IC50 fold-changes rather than raw IC50 data. Nearly 90% of the 11,387 viruses were from three WHO regions: Western Pacific, the Americas and Europe. Only 0.2% (n=27) showed highly reduced inhibition (HRI) against at least one of the four NAIs, usually oseltamivir, while 0.3% (n=39) showed reduced inhibition (RI). NA sequence data, available from the WHO CCs and from sequence databases (n=3661), were screened for amino acid substitutions associated with reduced NAI susceptibility. Those showing HRI were A(H1N1)pdm09 with NA H275Y (n=18), A(H3N2) with NA E119V (n=3) or NA R292K (n=1) and B/Victoria-lineage with NA H273Y (n=2); amino acid position numbering is A subtype and B type specific. Overall, approximately 99% of circulating viruses tested during the 2012-2013 period were sensitive to all four NAIs. Consequently, these drugs remain an appropriate choice for the treatment and prophylaxis of influenza virus infections

Identifying Audiences of E-Infrastructures - Tools for Measuring Impact

Research evaluation should take into account the intended scholarly and non-scholarly audiences of the research output. This holds too for research infrastructures, which often aim at serving a large variety of audiences. With research and research infrastructures moving to the web, new possibilities are emerging for evaluation metrics. This paper proposes a feasible indicator for measuring the scope of audiences who use web-based e-infrastructures, as well as the frequency of use. In order to apply this indicator, a method is needed for classifying visitors to e-infrastructures into relevant user categories. The paper proposes such a method, based on an inductive logic program and a Bayesian classifier. The method is tested, showing that the visitors are efficiently classified with 90% accuracy into the selected categories. Consequently, the method can be used to evaluate the use of the e-infrastructure within and outside academia