513 research outputs found

    Interstellar extinction at 10-20 microns

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    The IRAS low-resolution spectra (LRS) spectra of 117 stars of excellent signal/noise with optically thin silicate dust shells were analyzed. The stellar continua (assumed to be a cool black body) were subtracted, and the resulting dust shell spectra were fit with simple models F(sub lambda) assuming uniform mass loss and dust temperature as a function of distance from the star, calculated using the optical constants for silcates of Draine (1985). From the comparison of the spectra and the models, functions for the emissivity, kappa(sub lambda), were derived

    Observational Research on Star and Planetary System Formation

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    Institute scientists collaborate with a number of NASA Ames scientists on observational studies of star and planetary system formation to their mutual benefit. As part of this collaboration, SETI scientists have, from 1988 to the present: (1) contributed to the technical studies at NASA Ames of the Stratospheric Observatory for Infrared Astronomy (SOFIA), an infrared 2.5 meter telescope in a Boeing 747, which will replace the Kuiper Airborne Observatory (KAO), a 0.9 meter telescope in a Lockheed C-141. SOFIA will be an important facility for the future exploration of the formation of stars and planetary systems, and the origins of life, and as such will be an important future facility to SETI scientists; (2) worked with the Laboratory Astrophysics Group at Ames, carrying out laboratory studies of the spectroscopic properties of ices and pre-biotic organics, which could be formed in the interstellar or interplanetary media; (3) helped develop a photometric approach for determining the Frequency of Earth-Sized Inner Planets (FRESIP) around solar-like stars, a project (now called Kepler) which complements the current efforts of the SETI Institute to find evidence for extraterrestrial intelligence; and (4) carried out independent observational research, in particular research on the formation of stars and planetary systems using both ground-based telescopes as well as the KAO

    Addressing the needs of the childrenā€™s integrated workforce: A method for developing collaborative practice through joint learning

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    The delivery of welfare, health and educational provision to the majority of children aged 0ā€“18 in England is primarily led by local authorities via their childrenā€™s integrated service. In 2004 the childrenā€™s integrated service model was launched and it promised the benefits of an integrated and collaborative system of working, regarding flexibility and responsiveness to national policy, local development and capacity building (Robinson et al, 2008). However, the implementation and emergence of this model has been characterised by competing local and national agendas, practitioner misunderstanding and lack of trust, a lack of strong leadership and also financial restrictions. It can therefore be contended that conceptually childrenā€™s integrated services are not operating fully with a collaborative and integrated workforce. As a possible solution to the current situation, it is proposed that joint learning, along with a combined continual professional development (CPD) framework, be made available as a valuable starting point for such organisations. Learning and working together has benefits for children and practitioners, and especially, as this article will argue, for playwork practitioners

    The Relationship of Reading Achievement of Students with Disabilities and Least Restrictive Environment Practices

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    The purpose of this study was to investigate the relationship between Kentucky least restrictive environment (LRE) practices and the stateā€™s assessment annual measureable objectives (AMO) in reading for students with disabilities. This research was designed to determine whether districts achieved AMO targets for reading within LRE, and whether a relationship exists between special education studentsā€™ placement and assessment scores attained for the disability subpopulation in the Adequate Yearly Progress (AYP) Reports. Results from this study indicated that one district achieved the scale score for reading achievement. Nine districts achieved reading AMO targets due to safe harbor, while nine districts achieved reading AMO due to confidence interval for students with disabilities. Also, the results indicated a higher correlation for students who received services in a separate location for less than 20% of the school day

    Maternal iron status in early pregnancy and birth outcomes : insights from the Baby's Vascular health and Iron in Pregnancy study

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    Date of Acceptance: 16/03/2015 Acknowledgements N. A. A. was funded by a Wellcome Trust Research Training Fellowship (WT87789). H. J. M. and H. E. H. are supported by the Scottish Governmentā€™s Rural and Environment Science and Analytical Services. N. A. B. S. is supported by Cerebra. The authorsā€™ contributions are as follows: N. A. A. was responsible for organising the study conduct, data collection and database management, performed the statistical analysis, interpreted the results and drafted the paper. N. A. A., N. A. B. S., J. E. C., H. J. M. and D. C. G. contributed to the study concept and design, and interpretation of results. H. J. M. and H. E. H. analysed the laboratory samples. J. E. C. and D. C. G. provided advice on statistical strategy and analysis. All authors have fully participated in the reporting stage and have critically reviewed and approved the final draft of the paper. The authors declare no conflict of interestPeer reviewedPublisher PD

    Murine model of BCG lung infection: Dynamics of lymphocyte subpopulations in lung interstitium and tracheal lymph nodes

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    C57B1/6 female mice were infected with an intrapulmonary dose of 2.5Ɨ104 BCG(Mycobacterium bovis Bacillus Calmette-Guerin). Lymphocyte populations in lung interstitium and lung-associated tracheal lymph nodes (LN) were examined at 1,2, 4, 5, 6, 8 and 12 weeks after infection. BCG load in lungs peaked between 4-6 weeks post-infection and declined to very low levels by the 12th week of infection. Lung leukocytes were obtained over the course of infection by enzyme digestion of lung tissue followed by centrifugation over Percoll discontinuous density gradients. By 4 to 6 weeks after infection, numbers of lung leukocytes had more than doubled but the proportions of lymphocytes (about 70%), macrophages (about 18%) and granulocytes (about 12%) remained essentially unaltered. Flow cytometric studies indicated: (i) the total number of CD3+ T cells in lungs increased by 3-fold relative to uninfected controls at 5 to 6 weeks post-infection, but the relative proportions of CD4 and CD8 cells within the T cell compartment remained unaltered; (ii) relative proportion of NK cells in lungs declined by 30% but the total number of NK cells (NK1.1+) per lung increased by about 50%, 5-6 weeks post infection; (iii) tracheal LN underwent marked increase in size and cell recoveries (6-10-fold increase) beginning 4 weeks after infection. While both T and B cells contributed to the increase in cell recoveries from infected tracheal LNs, the T/B ratio declined significantly but CD4/CD8 ratio remained unaltered. In control mice, IFNĪ³ producing non-T cells outnumbered T cells producing IFNĪ³ . However, as the adaptive response to infection evolves, marked increase occur in the number of IFNĪ³ producing T cells, but not NK cells in the lungs. Thus, T cells are the primary cell type responsible for the adaptive IFNĪ³ response to pulmonary BCG infection. Few T cells in tracheal LN of BCG infected mice produce IFNĪ³, suggesting that maturational changes associated with migration to the lungs or residence in the lungs enhance the capability of some T cells to produce this cytokine

    Spitzer observations of extragalactic H II regions - III. NGC 6822 and the hot star, H II region connection

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    Using the short-high module of the Infrared Spectrograph on the Spitzer Space Telescope, we have measured the [S IV] 10.51, [Ne II] 12.81, [Ne III] 15.56, and [S III] 18.71-micron emission lines in nine H II regions in the dwarf irregular galaxy NGC 6822. These lines arise from the dominant ionization states of the elements neon (Ne++^{++}, Ne+^+) and sulphur (S3+^{3+}, S++^{++}), thereby allowing an analysis of the neon to sulphur abundance ratio as well as the ionic abundance ratios Ne+^+/Ne++^{++} and S3+^{3+}/S++^{++}. By extending our studies of H II regions in M83 and M33 to the lower metallicity NGC 6822, we increase the reliability of the estimated Ne/S ratio. We find that the Ne/S ratio appears to be fairly universal, with not much variation about the ratio found for NGC 6822: the median (average) Ne/S ratio equals 11.6 (12.2Ā±\pm0.8). This value is in contrast to Asplund et al.'s currently best estimated value for the Sun: Ne/S = 6.5. In addition, we continue to test the predicted ionizing spectral energy distributions (SEDs) from various stellar atmosphere models by comparing model nebulae computed with these SEDs as inputs to our observational data, changing just the stellar atmosphere model abundances. Here we employ a new grid of SEDs computed with different metallicities: Solar, 0.4 Solar, and 0.1 Solar. As expected, these changes to the SED show similar trends to those seen upon changing just the nebular gas metallicities in our plasma simulations: lower metallicity results in higher ionization. This trend agrees with the observations.Comment: 22 pages, 13 figures. To be published in MNRAS. reference added and typos fixed. arXiv admin note: text overlap with arXiv:0804.0828, which is paper II by Rubin et al. (2008
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