Search results for " star"
showing 10 items of 1194 documents
Leveraging Users' Likes in a Video Streaming P2P Platform
2014
This paper investigates how a p2p television platform can take advantage of the presence of frequent channel viewers to grant them a more satisfying service than to less regular spectators. The idea we explore is to learn beforehand about the users' interests, in order to cluster them in groups that display different behaviors; then, the neighborhood creation strategy and video chunk scheduling algorithm of the overlay is altered, with the aim of serving frequent spectators in a privileged manner, providing them with a faster access to the selected channel without overly penalizing less habitual customers. An analytical model is developed, to capture the difference in startup delay that the…
A photometric study of Be stars located in the seismology fields of COROT
2007
Context: In preparation for the COROT mission, an exhaustive photometric study of Be stars located in the seismology fields of the COROT mission has been performed. The very precise and long-time-spanned photometric observations gathered by the COROT satellite will give important clues of the origin of the Be phenomenon. Aims: The aim of this work is to find short-period variable Be stars located in the seismology fields of COROT and to study and characterise their pulsational properties. Methods: Light curves obtained at the Observatorio de Sierra Nevada together with data from Hipparcos and ASAS-3 of a total of 84 Be stars have been analysed in order to search for short-term variations. W…
The structure of coronal plasma in active stellar coronae from density measurements
2005
We have analyzed high-resolution X-ray spectra of a sample of 22 active stars observed with the High Energy Transmission Grating Spectrometer (HETGS) on Chandra in order to investigate their coronal plasma density, using the lines of the He-like ions O VII, Mg XI, and Si XIII. Si XII lines in all stars of the sample axe compatible with the low-density limit (i.e. n(e) = 10(30) erg/s); O VII lines yield much lower densities of a few 10(10) cm(-3). Our results indicate that the "hot" and "cool" plasma resides in physically different structures. Our findings imply remarkably compact coronal structures, especially for the hotter (similar to 7 MK) plasma emitting the Mg xi lines characterized by…
100+ Metrics for Software Startups : A Multi-Vocal Literature Review
2018
Używka wyklęta, czyli (nie)czułe wspomnienie o tabace
2020
Artykuł streszcza historię obecności tabaki w polskiej obyczajowości, koncentrując się na literackich świadectwach, mówiących o jej zażywaniu. W opracowaniu wspomniano m.in. o anonimowych tekstach, takich jak Poswarek Tabaki z Gorzałką (1636) czy Nauka, jako o dobrym także o złym używaniu proszku tabakowego (1650). Wspomniano również o publikacjach dotyczących tabaki, tłumaczonych z języków obcych w XVII i XVIII w. Autor przywołuje ponadto poezje przeciwników tytoniu, do których zaliczał się w Polsce Jan Andrzej Morsztyn czy też Bartłomiej Zimorowic. Odnotowano na koniec, że we współczesnej kulturze w związku z szerzącym się zakazem palenia tytoniu pojawia się problem traktowania palącego j…
Non-stationary dynamo and magnetospheric accretion processes of the classical T Tauri star V2129 Oph
2011
We report here the first results of a multiwavelength campaign focussing on magnetospheric accretion processes of the classical T Tauri star V2129 Oph. In this paper, we present spectropolarimetric observations collected in 2009 July with ESPaDOnS at the Canada-France-Hawaii Telescope and contemporaneous photometry secured with the SMARTS facility. Circularly polarized Zeeman signatures are clearly detected, both in photospheric absorption and accretion-powered emission lines, from time-series of which we reconstruct new maps of the magnetic field, photospheric brightness and accretion-powered emission at the surface of V2129 Oph using our newest tomographic imaging tool - to be compared wi…
Chandra study of the eclipsing M dwarf binary, YY Gem
2012
The eclipsing M dwarf binary system, YY Gem, was observed using Chandra covering 140 ks (2Prot) in total, split into two even exposures separated by 0.76 d (0.94 Prot). The system was extremely active: three energetic flares were observed over the course of these observations. The flaring and non-flaring states of the system are analysed in this paper. The activity level increased between the first and second observations even during the quiescent (non-flaring) phases. An analysis of the dynamics of the X-ray-emitting plasma suggests that both components are significantly active. Contemporaneous Hα spectra also suggest that both components show similar levels of activity. The primary star i…
Biomechanical comparison between sprint start, sled-pulling and selected squat type exercises
2012
The purpose of the present study was to compare kinetics, kinematics and muscle activity between sprint start, sled-pulling and selected squat type exercises and also to examine how different exercises and variables correlate with the performance time of the block start (10 m). Nine male athletes (4 sprinters, 3 decathlonists, 1 long jumper and 1 triple jumper; mean ± SD; age = 24.9 ± 3.9 yr; height = 180.4 ± 5.9 cm; weight = 80.3 ± 7.5 kg; 100 m record = 11.35 ± 0.29 s) performed measurements and different force-time, electromyographic (EMG) and kinematic variables were compared to sprint start. Most of the comparison was done to the block phase (the phase of force production towards start…
Effect of oil lamination between plasticized starch layers on film properties
2016
International audience; To reduce the hygroscopic character of biodegradable starch-based films, rapeseed oil was incorporated by lamination (starch-oil-starch 3-layers technique). The lipid lamination followed by starch solution casting step induced an emulsion type structure of dried films. Composite films are more opalescent and glossier than fatty free starch films. For all the films, structure is heterogeneous in the cross-section only. Adding fat induced a twice decrease of the tensile strength. Thermal gravimetry analysis did not show differences between films with and without oil. Lipid reduced the moisture absorption particularly at higher RH as well as the surface swelling index, …
Elektromagnētiskā lauka radītais darba vides risks un preventīvie pasākumi
2015
Elektromagnētiskā lauka radītais darba vides risks un preventīvie pasākumi. Maģistra darbs, 64 lappuses, 43 attēli, 2 tabulas, 24 literatūras avoti, 1 pielikums. Latviešu valodā. Elektromagnētiskais lauks, elektriskais lauks, magnētiskais lauks, nejonizējošais starojums, teorētiskie aprēķini. Darbā ir apskatīti elektromagnētiskie lauki un to iespējams radītais darba vides risks. Tiek veikti teorētiski elektromagnētiskā lauka stipruma aprēķini. Darbā tiek analizētas dažādas darba vides situācijas, kur lai novērtētu darba vides risku ir veikti elektromagnētiskā lauka mērījumi. Tiek sniegti dažādi preventīvo pasākumu piemēri. Secināts, ka elektromagnētiskais lauks ir bieži sastopams un ne vien…