2,102 research outputs found
THE ECOLOGY OF MIS RESEARCH: A TWENTY YEAR STATUS REVIEW
The debate concerning the legitimacy of MIS as a field of research has endured over the last decade. The absence of theories and lack of a cumulative research tradition have been areas of particular concern. The research reported in this article provides evidence on these important issues. The study systematically analyzed MIS articles in seven core journals over the period 1968-1988. The resulting database, consisting of 792 articles, was analyzed for themes and topics, and on the basis of type of article (empirical/non-empirical). The findings indicate that MIS research efforts have refocused in some areas, while much remains to be done in others. This study provides the opportunity to pause and reflect on the last twenty years of research in MIS and to take stock so that the research of the coming twenty years will extend and build upon the existing foundations
A "Starless" Core that Isn't: Detection of a Source in the L1014 Dense Core with the Spitzer Space Telescope
We present observations of L1014, a dense core in the Cygnus region previously thought to be starless, but data from the Spitzer Space Telescope show the presence of an embedded source. We propose a model for this source that includes a cold core, heated by the interstellar radiation field, and a low-luminosity internal source. The low luminosity of the internal source suggests a substellar object. If L1014 is representative, other "starless" cores may turn out to harbor central sources
Boundaries: A Boundary Setting and Social Competence Program for Parents and Youth
Learning to set age-appropriate boundaries is an integral element of positive youth development. Both parents and youth need guidance in rule-rsetting and negotiating boundaries. North Dakota State University Extension created Boundaries, a program using parent-youth relationships to teach the importance of setting and following rules or boundaries in various environments. Boundaries was written for 7th- through 12th-grade youth and their parents. This study provides an overview of the program’s objectives and curriculum and shares findings from evaluation efforts conducted with over 60 youth and adults during the program’s pilot phase. In six pilot sessions, respondents completed single-session retrospective questionnaires and answered open-ended questions, which were analyzed using descriptive statistics, paired t-tests, and thematic review. Adults reported higher satisfaction than youth with program content and instruction. Both youth and adults increased their knowledge of program-specific content related to boundaries and relationships. Open-ended responses offered positive feedback and suggestions for program improvement. Results suggested the program was perceived positively and increased youth and adult knowledge of boundary setting and social competence in family life and other settings. Key recommendations include increased rigorous evaluation to measure program impacts and focus on effective implementation strategies for the program
Spitzer Space Telescope Spectroscopy of Ices toward Low-Mass Embedded Protostars
Sensitive 5-38 μm Spitzer Space Telescope and ground-based 3-5 μm spectra of the embedded low-mass protostars B5 IRS1 and HH 46 IRS show deep ice absorption bands superposed on steeply rising mid-infrared continua. The ices likely originate in the circumstellar envelopes. The CO_2 bending mode at 15 μm is a particularly powerful tracer of the ice composition and processing history. Toward these protostars, this band shows little evidence for thermal processing at temperatures above 50 K. Signatures of lower temperature processing are present in the CO and OCN^- bands, however. The observed CO2 profile indicates an intimate mixture with H_(2)O, but not necessarily with CH_(3)OH, in contrast to some high-mass protostars. This is consistent with the low CH_(3)OH abundance derived from the ground-based L-band spectra. The CO_2 : H_(2)O column density ratios are high in both B5 IRS1 and HH 46 IRS (~35%). Clearly, the Spitzer spectra are essential for studying ice evolution in low-mass protostellar environments and for eventually determining the relation between interstellar and solar system ices
Hydrogen and deuterium diffusion in non-stoichiometric spinel
High pressure/temperature annealing experiments are used to determine diffusivities of H+ and D+ in non-stoichiometric spinel, a low-pressure analogue for nominally anhydrous minerals in Earth’s mantle. Data are fitted to the following Arrhenius law: Diffusivity (m2/s) = 4 ± 1 × 10−12 exp(−54 ± 2 kJ mol−1/RT). At low temperatures, H+ and D+ diffusion in non-stoichiometric spinel is charge balanced by flux of O vacancies, with infrared data consistent with protonation of both octahedral and tetrahedral O–O edges in non-stoichiometric spinel, and additional fine structure due to Mg–Al mixing and/or coupling of structurally incorporated H+ with cation vacancies. Absence of changes in the fine structure of O–H absorption bands indicates that H+ can become locally coupled and uncoupled to other defects during bulk diffusion. As such, proton conductivity in spinel group minerals, arising from faster flux of uncoupled H+, can only be calculated from H+ mobility data if the extent of defect coupling is constrained.Publisher PDFPeer reviewe
AVERT2(a very early rehabilitation trial, a very effective reproductive trigger): retrospective observational analysis of the number of babies born to trial staff
Objective: To report the number of participants needed to recruit per baby born to trial staff during AVERT, a large international trial on acute stroke, and to describe trial management consequences.
Design: Retrospective observational analysis.
Setting: 56 acute stroke hospitals in eight countries.
Participants: 1074 trial physiotherapists, nurses, and other clinicians.
Outcome measures: Number of babies born during trial recruitment per trial participant recruited.
Results: With 198 site recruitment years and 2104 patients recruited during AVERT, 120 babies were born to trial staff. Births led to an estimated 10% loss in time to achieve recruitment. Parental leave was linked to six trial site closures. The number of participants needed to recruit per baby born was 17.5 (95% confidence interval 14.7 to 21.0); additional trial costs associated with each birth were estimated at 5736 Australian dollars on average.
Conclusion: The staff absences registered in AVERT owing to parental leave led to delayed trial recruitment and increased costs, and should be considered by trial investigators when planning research and estimating budgets. However, the celebration of new life became a highlight of the annual AVERT collaborators’ meetings and helped maintain a cohesive collaborative group
The Spitzer c2d Survey of Large, Nearby, Interstellar Clouds. VIII. Serpens Observed with MIPS
We present maps of 1.5 deg^2 of the Serpens dark cloud at 24, 70, and 160 μm observed with the Spitzer Space Telescope MIPS camera. We describe the observations and briefly discuss the data processing carried out by the c2d team on these data. More than 2400 compact sources have been extracted at 24 μm, nearly 100 at 70 μm, and four at 160 μm. We estimate completeness limits for our 24 μm survey from Monte Carlo tests with artificial sources inserted into the Spitzer maps. We compare source counts, colors, and magnitudes in the Serpens cloud to two reference data sets: a 0.50 deg^2 set on a low-extinction region near the dark cloud, and a 5.3 deg^2 subset of the SWIRE ELAIS N1 data that was processed through our pipeline. These results show that there is an easily identifiable population of young stellar object candidates in the Serpens cloud that is not present in either of the reference data sets. We also show a comparison of visual extinction and cool dust emission illustrating a close correlation between the two and find that the most embedded YSO candidates are located in the areas of highest visual extinction
The Spitzer c2d Survey of Large, Nearby, Interstellar Clouds. VII. Ophiuchus Observed with MIPS
We present maps of 14.4 deg^2 of the Ophiuchus dark clouds observed by the Spitzer Space Telescope Multiband Imaging Photometer for Spitzer (MIPS). These high-quality maps depict both numerous point sources and extended dust emission within the star-forming and non–star-forming portions of these clouds. Using PSF-fitting photometry, we detect 5779 sources at 24 μm and 81 sources at 70 μm at the 10 σ level of significance. Three hundred twenty-three candidate young stellar objects (YSOs) were identified according to their positions on the MIPS/2MASS K versus color-magnitude diagrams, as compared to 24 μm detections in the SWIRE extragalactic survey. We find that more than half of the YSO candidates, and almost all those with protostellar Class I spectral energy distributions, are confined to the known cluster and aggregates
The c2d Spitzer Spectroscopic Survey Of Ices Around Low-Mass Young Stellar Objects. I. H2O And The 5-8 Mu M Bands
To study the physical and chemical evolution of ices in solar-mass systems, a spectral survey is conducted of a sample of 41 low-luminosity YSOs (L similar to 0.1-10 L-circle dot) using 3-38 mu m Spitzer and ground-based spectra. The sample is complemented with previously published Spitzer spectra of background stars and with ISO spectra of well-studied massive YSOs (L similar to 10(5) L-circle dot). The long-known 6.0 and 6.85 mu m bands are detected toward all sources, with the Class 0-type YSOs showing the deepest bands ever observed. The 6.0 mu m band is often deeper than expected from the bending mode of pure solid H2O. The additional 5-7 mu m absorption consists of five independent components, which, by comparison to laboratory studies, must be from at least eight different carriers. Much of this absorption is due to simple species likely formed by grain surface chemistry, at abundances of 1%-30% for CH3OH, 3%-8% for NH3, 1%-5% for HCOOH, similar to 6% for H2CO, and similar to 0.3% for HCOO- relative to solid H2O. The 6.85 mu m band has one or two carriers, of which one may be less volatile than H2O. Its carrier(s) formed early in the molecular cloud evolution and do not survive in the diffuse ISM. If an NH4+- containing salt is the carrier, its abundance relative to solid H2O is similar to 7%, demonstrating the efficiency of low-temperature acid-base chemistry or cosmic-ray-induced reactions. Possible origins are discussed for enigmatic, very broad absorption between 5 and 8 mu m. Finally, the same ices are observed toward massive and low-mass YSOs, indicating that processing by internal UV radiation fields is a minor factor in their early chemical evolution.NWO SpinozaNOVAEuropean Research Training Network PLANETS HPRN-CT-2002-00308NASA Origins NAG5-13050NASA Hubble Fellowship 01201.01NASA NAS 5-26555Astronom
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