1,724,225 research outputs found
NGC 7421: Surfing the Intracluster Medium?
No full textAbstractNGC 7421 is a barred spiral that is displaced from the centre of its optical envelope, and has a ‘bow-shock’-like western boundary, both suggestive of interaction with an intracluster medium. We have used five configurations of the ATCA to map the distribution and kinematics of HI in NGC 7421, and find supportive evidence for this scenario in the form of an HI ‘wake’. When compared with ROSAT PSPC observations of the diffuse hot gas in the surrounding group of galaxies, these new ATCA results will allow us to place new constraints on the density and dynamics of the intracluster medium.</jats:p
The dependence of cyanobacterium Gloeobacter violaceus PCC 7421 photosynthes on different cation environment
No full textВивчали вплив катіонного складу середовища інкубації на ріст та фотосинтетичне виділення кисню ціанобактерією Gloeobacter violaceus РСС 7421.
Показано, що в нейтральних умовах заміна стандартних 18 мМ N a+ на
18 мМ К+ або 9 мМ Са2+ не впливають на ріст та фотосинтез G. violaceus. У
лужному середовищі ріст та фотосинтетичне виділення кисню інгібуються,
якщо натрій замінено на калій. Проте перенос культури до стандартного
“натрієвого” або модифікованого “кальцієвого” середовища призводить
до поновлення фотосинтетичного виділення кисню.
Висловлено припущення, що спроможність G. violaceus до фотосинтезу залежить від рівня енергізації зовнішньої мембрани клітин, яка, в свою чергу,
контролюється ефективністю використання G. violaceus різних типів енергетичного спряження.Изучали влияние катионного состава среды инкубации на рост и фотосинтетическое
выделение кислорода цианобактерией Gloeobacter violaceus. Показано, что в нейтральнойсреде замена стандартных 18 мМ N a+ на 18 мМ К+ или 9 мМ Са2+ не влияет на рост и
фотосинтез G. violaceus. В условиях щелочной среды рост и фотосинтетическое выделение
кислорода ингибируется в среде, где натрий заменен калием. Однако перенос культуры в
стандартную натриевую или модифицированную “кальциевую” среду приводил к возобновлению фотосинтетического выделения кислорода.
Высказано предположение, что фотосинтетическая способность G. violaceus РСС 7421
зависит от уровня энергизации внешней мембраны, которая, в свою очередь, контролируется эффективностью использования G. violaceus РСС 7421 различных циклов энергетического сопряжения.It was shown that the growth rate of cyanobacteria Gloeobacter violaceus PCC 7421 was
maximal in calcium and sodium media under alkaline pH while in potassium medium it was not
observed. There were no differences in the growth when pH of the medium was neutral. After
addition of Ca2+ or N a+ the growth rate and 0 2 production was resumed.
It was supposed that cyanobacteria Gloeobacter violaceus PCC 7421 can use N a+ and Ca2+ as
coupling ion under low A|iH+ background
The dependence of cyanobacterium Gloeobacter violaceus PCC 7421 photosynthes on different cation environment
No full textВивчали вплив катіонного складу середовища інкубації на ріст та фотосинтетичне виділення кисню ціанобактерією Gloeobacter violaceus РСС 7421.
Показано, що в нейтральних умовах заміна стандартних 18 мМ N a+ на
18 мМ К+ або 9 мМ Са2+ не впливають на ріст та фотосинтез G. violaceus. У
лужному середовищі ріст та фотосинтетичне виділення кисню інгібуються,
якщо натрій замінено на калій. Проте перенос культури до стандартного
“натрієвого” або модифікованого “кальцієвого” середовища призводить
до поновлення фотосинтетичного виділення кисню.
Висловлено припущення, що спроможність G. violaceus до фотосинтезу залежить від рівня енергізації зовнішньої мембрани клітин, яка, в свою чергу,
контролюється ефективністю використання G. violaceus різних типів енергетичного спряження.Изучали влияние катионного состава среды инкубации на рост и фотосинтетическое
выделение кислорода цианобактерией Gloeobacter violaceus. Показано, что в нейтральнойсреде замена стандартных 18 мМ N a+ на 18 мМ К+ или 9 мМ Са2+ не влияет на рост и
фотосинтез G. violaceus. В условиях щелочной среды рост и фотосинтетическое выделение
кислорода ингибируется в среде, где натрий заменен калием. Однако перенос культуры в
стандартную натриевую или модифицированную “кальциевую” среду приводил к возобновлению фотосинтетического выделения кислорода.
Высказано предположение, что фотосинтетическая способность G. violaceus РСС 7421
зависит от уровня энергизации внешней мембраны, которая, в свою очередь, контролируется эффективностью использования G. violaceus РСС 7421 различных циклов энергетического сопряжения.It was shown that the growth rate of cyanobacteria Gloeobacter violaceus PCC 7421 was
maximal in calcium and sodium media under alkaline pH while in potassium medium it was not
observed. There were no differences in the growth when pH of the medium was neutral. After
addition of Ca2+ or N a+ the growth rate and 0 2 production was resumed.
It was supposed that cyanobacteria Gloeobacter violaceus PCC 7421 can use N a+ and Ca2+ as
coupling ion under low A|iH+ background
CONSTRAINTS ON JET FORMATION MECHANISMS WITH THE MOST ENERGETIC GIANT OUTBURSTS IN MS 0735+7421
No full textGiant X-ray cavities lie in some active galactic nuclei (AGNs) locating in central galaxies of clusters, which are estimated to have stored 10(55)-10(62) erg of energy. Most of these cavities are thought to be inflated by jets of AGNs on a timescale of greater than or similar to 10(7) years. The jets can be either powered by rotating black holes or the accretion disks surrounding black holes, or both. The observations of giant X- ray cavities can therefore be used to constrain jet formation mechanisms. In this work, we choose the most energetic cavity, MS 0735+7421, with stored energy similar to 10(62) erg, to constrain the jet formation mechanisms and the evolution of the central massive black hole in this source. The bolometric luminosity of the AGN in this cavity is similar to 10(-5) L-Edd, however, the mean power of the jet required to inflate the cavity is estimated as similar to 0.02L(Edd), which implies that the source has previously experienced strong outbursts. During outbursts, the jet power and the mass accretion rate should be significantly higher than its present values. We construct an accretion disk model in which the angular momentum and energy carried away by jets are properly included to calculate the spin and mass evolution of the massive black hole. In our calculations, different jet formation mechanisms are employed, and we find that the jets generated with the Blandford-Znajek (BZ) mechanism are unable to produce the giant cavity with similar to 10(62) erg in this source. Only the jets accelerated with a combination of the Blandford-Payne and BZ mechanisms can successfully inflate such a giant cavity if the magnetic pressure is close to equipartition with the total (radiation + gas) pressure of the accretion disk. For a dynamo-generated magnetic field in the disk, such an energetic giant cavity can be inflated by the magnetically driven jets only if the initial black hole spin parameter a(0) greater than or similar to 0.95. Our calculations show that the final spin parameter a of the black hole is always similar to 0.9-0.998 for all the computational examples that can provide sufficient energy for the cavity of MS 0735+7421
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
The XMM-Newton View of MS0735+7421: the Most Energetic AGN Outburst in a Galaxy Cluster
No full textWe discuss the possible cosmological effects of powerful AGN outbursts in galaxy clusters by starting from the results of an XMM-Newton observation of the supercavity cluster MS0735+7421
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Search for cold gas along radio lobes in the cooling core galaxies MS0735.6+7421 and M87
No full textWe report CO observations towards MS0735.6+7421 a distant
cooling core galaxy, and towards M87, the nearest cooling core in
the center of the Virgo cluster. Both galaxies contain radio
cavities that are thought to be responsible for the heating that can
regulate or stop the cooling of the surrounding gas. In this
feedback process, there could still be some gas cooling along
filaments, along the borders of the radio cavities. Molecular gas
is known to exist in clusters with cooling cores, in long and thin
filaments that can be formed behind the rising bubbles inflated by
the central AGN. CO emission was searched for at several locations
along the radio lobes of those two galaxies, but only upper limits
were found. These correspond to cold gas mass limits of a few
109 for each pointing in MS0735.6+7421, and a few
106 in M87. This non detection means that either the
cooling is strongly reduced by the AGN feedback or that the gas is
cooling in very localized places like thin filaments, possibly
diluted in the large beam for MS0735.6+7421. For M87, the AGN
heating appears to have stopped the cooling completely.
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