105 research outputs found
The Red MSX Source Survey: The Massive Young Stellar Population of Our Galaxy
We present the Red MSX Source survey, the largest statistically selected catalog of young massive protostars and H II regions to date. We outline the construction of the catalog using mid- and near-infrared color selection. We also discuss the detailed follow up work at other wavelengths, including higher spatial resolution data in the infrared. We show that within the adopted selection bounds we are more than 90% complete for the massive protostellar population, with a positional accuracy of the exciting source of better than 2 arcsec. We briefly summarize some of the results that can be obtained from studying the properties of the objects in the catalog as a whole; we find evidence that the most massive stars form: (1) preferentially nearer the Galactic center than the anti-center; (2) in the most heavily reddened environments, suggestive of high accretion rates; and (3) from the most massive cloud cores
The RMS survey: near-IR spectroscopy of massive young stellar objects
Near-infrared H- and K-band spectra are presented for 247 objects, selected from the Red MSX Source (RMS) survey as potential young stellar objects (YSOs). 195 (∼80 per cent) of the targets are YSOs, of which 131 are massive YSOs (L BOL > 5×10 3 L ⊙ , M > 8 M ⊙ ). This is the largest spectroscopic study of massive YSOs to date, providing a valuable resource for the study of massive star formation. In this paper, we present our exploratory analysis of the data. The YSOs observed have a wide range of embeddedness (2.7 < A V < 114), demonstrating that this study covers minimally obscured objects right through to very red, dusty sources. Almost all YSOs show some evidence for emission lines, though there is a wide variety of observed properties. The most commonly detected lines are Brγ, H 2 , fluorescent Fe ii, CO bandhead, [Fe ii] and He i 2-1 1 S- 1 P, in order of frequency of occurrence. In total, ∼40 per cent of the YSOs display either fluorescent Fe ii 1.6878 μm or CO bandhead emission (or both), indicative of a circumstellar disc; however, no correlation of the strength of these lines with bolometric luminosity was found. We also find that ∼60 per cent of the sources exhibit [Fe ii] or H 2 emission, indicating the presence of an outflow. Three quarters of all sources have Brγ in emission. A good correlation with bolometric luminosity was observed for both the Brγ and H 2 emission line strengths, covering 1 < L BOL < 3.5 × 10 5 L ⊙ . This suggests that the emission mechanism for these lines is the same for low-, intermediate- and high-mass YSOs, i.e. high-mass YSOs appear to resemble scaled-up versions of low-mass YSOs. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
Jet Formation at the Sea Ice Edge
Mesoscale jet formation due to the Coriolis Effect is well understood over sharp changes in surface roughness such as coastlines. This sharp change in surface roughness is experienced by the atmosphere flowing over, and ocean flowing under, a compacted sea ice edge. Sea ice edge jets have been observed. This thesis presents a study of a dynamic sea ice edge responding to atmospheric and oceanic jet formation during various wind and ocean current conditions. An idealised analytical model of sea ice drift is created using a momentum balance and the viscous plastic rheology. This is compared to an ice edge in the Los Alamos sea ice climate model (CICE) run on an idealised domain. A scheme has been developed which analyses sea ice concentration and adds jets to the CICE model forcing data. The response of the model to jet formation is tested at various resolutions. The formation of atmospheric jets at the sea ice edge is shown to increase the wind speed parallel to the sea ice edge and results in the formation of a sea ice edge jet. The increase is dependent upon the angle between the ice and wind and results in an increase in ice transport along the sea ice edge of 40%. Observa- tions and climate model data of the polar oceans has been analysed to show areas of likely atmospheric jet formation with the Fram Strait being of particular interest. The possibility of oceanic jet formation and the resultant effect upon the sea ice edge is less conclusive. The coupling between the components of climate models is currently crude and does not allow for jet formation. Most climate model also misrepresent the ice drift through the Fram Strait leading to errors in the prediction of Arctic sea ice extent
Конкурентоспособность фирм в условиях рыночной экономики
Объектом исследования является: предприятие – АО "Сибирская Аграрная Группа".
Цель работы – разработать рекомендации по повышению конкурентоспособности АО "Сибирская Аграрная Группа".
В процессе исследования проводились оценка конкурентоспособности, анализ основных конкурентов и разработка мероприятий по повышению конкурентоспособности АО "Сибирская Аграрная Группа".
Актуальность темы выпускной квалифицированной работы состоит в том, что в условиях стремительно развивающейся рыночной экономики конкурентоспособность предприятия, определяет основу для разработки экономической стратегии, помогает проанализировать состояние и возможность для предприятия выдержать конкуренцию.The object of the study is: the enterprise is JSC "Siberian Agrarian Group".
The purpose of the work is to develop recommendations for increasing the competitiveness of JSC "Siberian Agrarian Group".
In the process of the study, competitiveness assessment, analysis of the main competitors and development of measures to increase the competitiveness of JSC "Siberian Agrarian Group" were conducted.
The topicality of the topic of the final qualified work is that, in a rapidly developing market economy, the competitiveness of an enterprise, determines the basis for the development of an economic strategy, helps to analyze the state and the opportunity for an enterprise to withstand competition
Towards a supertree of Arthropoda:a species-level supertree of the spiny, slipper and coral lobsters (Decapoda: Achelata)
While supertrees have been built for many vertebrate groups (notably birds, mammals and dinosaurs), invertebrates have attracted relatively little attention. The paucity of supertrees of arthropods is particularly surprising given their economic and ecological importance, as well as their overwhelming contribution to biodiversity. The absence of comprehensive archives of machine-readable source trees, coupled with the need for software implementing repeatable protocols for managing them, has undoubtedly impeded progress. Here we present a supertree of Achelata (spiny, slipper and coral lobsters) as a proof of concept, constructed using new supertree specific software (the Supertree Toolkit; STK) and following a published protocol. We also introduce a new resource for archiving and managing published source trees. Our supertree of Achelata is synthesised from morphological and molecular source trees, and represents the most complete species-level tree of the group to date. Our findings are consistent with recent taxonomic treatments, confirming the validity of just two families: Palinuridae and Scyllaridae; Synaxidae were resolved within Palinuridae. Monophyletic Silentes and Stridentes lineages are recovered within Palinuridae, and all sub-families within Scyllaridae are found to be monophyletic with the exception of Ibacinae. We demonstrate the feasibility of building larger supertrees of arthropods, with the ultimate objective of building a complete species-level phylogeny for the entire phylum using a divide and conquer strategy
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