A Spectroscopic Study of OB+ Stars.

We present here the results of an analysis of spectroscopic and photometric observations of OB\sp+ stars. These mostly luminous young stars were selected from a survey of the Milky Way that is complete to the 12th B magnitude and covers 360\sp\circ of galactic longitude and {\pm}10\sp\circ of galactic latitude. We determined the MK spectral types of 291 OB\sp+ stars; a detailed discussion of the MK system and the process of spectral classification is given. Using the MK types and UBV photometry, we derived the distances to these stars and to other OB\sp+ stars that had published MK spectral types. We thus have distances to nearly all of the non-emission OB\sp+ stars in the Milky Way down to the 12th B magnitude. We derive the space distribution of these stars and compare it with previous studies of Galactic structure. The color excesses derived from these data are plotted to show the distribution of dust in the Galactic plane out to several kpc. As is often the case in surveys of this nature, several astrophysically interesting peculiar spectra were discovered, and these too are described

Listening to children's voices in the science classroom

Dear Laluprasad,   Please upload articles attached here.  Number of articles – 20   http://ec2-13-58-91-216.us-   User Name : Sachin Password: sachin     Journal Title : Learning Curve Divisions : Foundation Publications Publisher : Azim Premji Foundation Issue Number : 12 Year & month : April 2009 Email ID : [email protected] Key words : Education, Elementary education, Early childhood education Subject : Education   Foundation site : http://azimpremjifoundation. 14/08/ 18 Tuesday work 1)Small Science Series: Textbooks, Workbooks and Teachers' Books for Classes I to V http://ec2-13-58-91-216.us-east-2.compute.amazonaws.com/593/ 2) "Surely You're Joking, Mr Feynman!" - Adventures of a Curious Character http://ec2-13-58-91-216.us-east-2.compute.amazonaws.com/599/ 3) Bringing the Laboratory into the Classroom: Bringing Inventive Thinking into the Mind http://ec2-13-58-91-216.us-east-2.compute.amazonaws.com/602/ 4) Burning Questions and their Power to Kindle a Fire http://ec2-13-58-91-216.us-east-2.compute.amazonaws.com/605/ 5) Celebrating Science: The Science Mela http://ec2-13-58-91-216.us-east-2.compute.amazonaws.com/608/ 6) Special issue on Science Education http://ec2-13-58-91-216.us-east-2.compute.amazonaws.com/665/ 7) Developing Scientific Temper http://ec2-13-58-91-216.us-east-2.compute.amazonaws.com/670/ 8) Developing Teachers http://ec2-13-58-91-216.us-east-2.compute.amazonaws.com/676/ 9) Did Scientists Ever Err? http://ec2-13-58-91-216.us-east-2.compute.amazonaws.com/679/ 10) From the real to the abstract http://ec2-13-58-91-216.us-east-2.compute.amazonaws.com/682/ 11. Journey Of Science Through Time http://ec2-13-58-91-216.us-east-2.compute.amazonaws.com/686/ 12) Listening to Children's Voices in the Science Classroom When there are no negative consequences for saying something, the real exploration of ideas begins. Sometimes, a really bright child gives a most wonderful answer, with all the 'ifs' and 'buts' covered. Tempting though it is, the teacher would do best to not acknowledge it as such right away - until the rest of the class is asked what they think. Otherwise no one is motivated to seek an answer of their own. And of course one should acknowledge the first answer after all have had their say.A large body of research in science education alternative concepts quite different from what is taught in the science class.Most often, the exercise of teaching changes children's theories come as a complete surprise to them

Effects of canagliflozin on cardiovascular biomarkers in older adults with type 2 diabetes

Background: Sodium glucose co-transporter 2 (SGLT2) inhibitors may reduce cardiovascular and heart failure risk in patients with type 2 diabetes mellitus (T2DM). Objectives: To examine the effects of canagliflozin on cardiovascular biomarkers in older patients with T2DM. Methods: In 666 T2DM patients randomized to receive canagliflozin 100 or 300 mg or placebo, we assessed median percent change in serum N-terminal pro-B type natriuretic peptide (NT-proBNP), high-sensitivity troponin I (hsTnI) , soluble (s)ST2, and galectin-3 from baseline to 26, 52, and 104 weeks. Results: Both serum NT-proBNP and serum hsTnI levels increased in placebo recipients but remained largely unchanged in those randomized to canagliflozin. Hodges-Lehmann estimates of the difference in median percent change between pooled canagliflozin and placebo were –15.0%, –16.1%, and –26.8% for NT-proBNP, and –8.3%, –11.9%, and –10.0% for hsTnI at weeks 26, 52, and 104, respectively (all P <0.05). Serum sST2 was unchanged with canagliflozin and placebo over 104 weeks. Serum galectin-3 modestly increased from baseline with canagliflozin versus placebo, with significant differences observed at 26 and 52 weeks but not at 104 weeks. These results remained unchanged when only patients with complete samples were assessed. Conclusions: Compared to placebo, treatment with canagliflozin delayed rise in serum NT-proBNP and hsTnI over 2 years in older T2DM patients. These cardiac biomarker data provide support for beneficial cardiovascular effect of SGLT2 inhibitors in T2DM

Photometry and low resolution spectroscopy of hot post-AGB candidates

We have obtained Johnson U, B, V and Cousins R, I photometry and low resolution spectra of a small sample of hot post-AGB candidates. Using the present data in combination with JHK data from 2MASS, infrared data from the MSX catalog and the IRAS fluxes, we have studied the spectral energy distribution (SED) of these stars. Using the DUSTY code we have estimated the dust temperatures, the distances to the stars, the mass-loss rates, angular radii of the inner boundary of the dust envelopes and dynamical ages from the tip of the AGB. These candidates have also been imaged through a narrow band H-alpha filter, to search for nebulosity around the central stars. Our H-alpha images revealed the bipolar morphology of the low excitation PN IRAS 17395-0841 with an angular extent of 2.8arcsec. The bipolar lobes of IRAS 17423-1755 in H-alpha were found to have an angular extent of 3.5arcsec (south-east lobe) and 2.2arcsec (north-west lobe). The dust envelope characteristics, low resolution spectrum and IRAS colors suggest that IRAS 18313-1738 is similar to the proto-planetary nebula (PPN) HD 51585. The SED of IRAS 17423-1755, IRAS 18313-1738 and IRAS 19127+1717 show a warm dust component (in addition to the cold dust) which may be due to recent and ongoing mass-loss.Comment: 20 pages, 6 figures, h-alpha figure compressed with XV, paper accepted for publication in Astronomy & Astrophysic

Variability of Hot Supergiant IRAS 19336-0400 in the Early Phase of its Planetary Nebula Ionization

We present photoelectric and spectral observations of a hot candidate proto-planetary nebula - early B-type supergiant with emission lines in spectrum - IRAS 19336-0400. The light and color curves display fast irregular brightness variations with maximum amplitudes Delta V=0.30 mag, Delta B=0.35 mag, Delta U=0.40 mag and color-brightness correlations. By the variability characteristics IRAS 19336-0400 appears similar to other hot proto-planetary nebulae. Based on low-resolution spectra in the range lambda 4000-7500 A we have derived absolute intensities of the emission lines H_alpha, H_beta, H_gamma, [SII], [NII], physical conditions in gaseous nebula: n_e=10^4 cm^{-3}, T_e=7000 \pm 1000 K. The emission line H_alpha, H_beta equivalent widths are found to be considerably variable and related to light changes. By UBV-photometry and spectroscopy the color excess has been estimated: E_{B-V}=0.50-0.54. Joint photometric and spectral data analysis allows us to assume that the star variability is caused by stellar wind variations.Comment: 11 pages, 6 figures, 2 tables, accepted for publication in Pis'ma Astron. Zh. (Astronomy Letters

Essential function for ErbB3 in breast cancer proliferation

The overexpression of the ErbB family of tyrosine kinase receptors is thought to be important in the development of many breast tumours. To date, most attention has focused on the ErbB2 receptor. Now, in a recent report, it has been shown that ErbB3 is a critical partner for the transforming activity of ErbB2 in breast cancer cells. Importantly, the proliferative signals from this transforming complex appear to act via the PI-3 kinase pathway

Evolution from AGB to planetary nebula in the MSX survey

We investigate the evolution of oxygen- and carbon-rich AGB stars, post-AGB objects, and planetary nebulae using data collected mainly from the MSX catalogue. Magnitudes and colour indices are compared with those calculated from a grid of synthetic spectra that describe the post-AGB evolution beginning at the onset of the superwind. We find that carbon stars and OH/IR objects form two distinct sequences in the (K-[8.3])x([8.3]-[14.7]) MSX colour diagram. OH/IR objects are distributed in two groups: the bluest ones are crowded near [14.7]-[21.3]=1 and [8.3]-[14.7]=2, and a second, redder group is spread over a large area in the diagram, where post-AGB objects and planetary nebulae are also found. High mass-loss rate OH/IR objects, post-AGB stars, and planetary nebulae share the same region in the (K-[8.3])x([8.3]-[14.7]) and [14.7]-[21.3]x([8.3]-[14.7]) colour-colour diagrams. This region in the diagram is clearly separated from a bluer one where most OH/IR stars are found. We use a grid of models of post-AGB evolution, which are compared with the data. The gap in the colour-colour diagrams is interpreted as the result of the rapid trajectory in the diagram of the stars that have just left the AGB.Comment: 11 pages, 5 postscript figures, LaTeX, uses Astronomy and Astrophysics macro aa.cls, graphicx package, to be published in Astronomy and Astrophysics, Also available at: http://www.astro.iag.usp.br/~macie

Astrophysical parameters of the peculiar X-ray transient IGR J11215−5952

Context. The current generation of X-ray satellites has discovered many new X-ray sources that are difficult to classify within the well-described subclasses. The hard X-ray source IGR J11215-5952 is a peculiar transient, displaying very short X-ray outbursts every 165 days. Aims: To characterise the source, we obtained high-resolution spectra of the optical counterpart, HD 306414, at different epochs, spanning a total of three months, before and around the 2007 February outburst with the combined aims of deriving its astrophysical parameters and searching for orbital modulation. Methods: We fit model atmospheres generated with the FASTWIND code to the spectrum, and used the interstellar lines in the spectrum to estimate its distance. We also cross-correlated each individual spectrum to the best-fit model to derive radial velocities. Results: From its spectral features, we classify HD 306414 as B0.5 Ia. From the model fit, we find Teff ≈ 24 700 K and log g ≈ 2.7, in good agreement with the morphological classification. Using the interstellar lines in its spectrum, we estimate a distance to HD 306414 d ≳ 7 kpc. Assuming this distance, we derive R∗ ≈ 40 R⊙ and Mspect ≈ 30 M⊙ (consistent, within errors, with Mevol ≈ 38 M⊙, and in good agreement with calibrations for the spectral type). Analysis of the radial velocity curve reveals that radial velocity changes are not dominated by the orbital motion, and provide an upper limit on the semi-amplitude for the optical component Kopt ≲ 11 ± 6 km s-1. Large variations in the depth and shape of photospheric lines suggest the presence of strong pulsations, which may be the main cause of the radial velocity changes. Very significant variations, uncorrelated with those of the photospheric lines are seen in the shape and position of the Hα emission feature around the time of the X-ray outburst, but large excursions are also observed at other times. Conclusions: HD 306414 is a normal B0.5 Ia supergiant. Its radial velocity curve is dominated by an effect that is different from binary motion, and is most likely stellar pulsations. The data available suggest that the X-ray outbursts are caused by the close passage of the neutron star in a very eccentric orbit, perhaps leading to localised mass outflow