1,721,050 research outputs found
Angular momentum transfer in dark matter halos: Erasing the cusp
No full textWe propose that angular momentum transfer from the baryons to the dark matter (DM) during the early stages of galaxy formation can flatten the halo inner density profile and modify the halo dynamics. We compute the phase-space distribution function of DM halos that corresponds to the density and anisotropy profiles obtained from N-body simulations in the concordance cosmology. We then describe an injection of angular momentum into the halo by modifying the distribution function and show that the system evolves into a new equilibrium configuration; the latter features a constant central density and a tangentially dominated anisotropy profile in the inner regions, while the structure is nearly unchanged beyond 10% of the virial radius. Then we propose a toy model to account for such a halo evolution, based on the angular momentum exchange due to dynamical friction; at the epoch of galaxy formation this is efficiently exerted by the DM onto the gas clouds spiralling down the potential well. The comparison between the angular momentum profile gained by the halo through dynamical friction and that provided by the perturbed distribution function reveals a surprising similarity, hinting at the reliability of the process
Impact of sex and age on the mevalonate pathway in the brain: A focus on effects induced by maternal exposure to exogenous compounds
No full textThe mevalonate pathway produces cholesterol and other compounds crucial for numerous cellular processes. It is well known that age and sex modulate this pathway in the liver. Recently, similar effects were also noted in different brain areas, suggesting that alterations of the mevalonate pathway are at the root of marked sex-specific disparities in some neurodevelopmental disorders related to disturbed cholesterol homeostasis. Here, we show how the mevalonate pathway is modulated in a sex-, age-and region-specific manner, and how maternal exposure to exogenous compounds can disturb the regulation of this pathway in the brain, possibly inducing functional alterations
Measuring the spin of spiral galaxies
No full textA Birthday Celebration of the Contributions of Bernard Jones to our unserstanding of the Universe. On June 3rd, 2006, Bernard Jones will celebrate his 60th birthday. To celebrate this occasion and pay tribute to his substantial contributions to science and the scientific world we organize a dedicated conference on cosmology, galaxy and cosmic structure formation and star formation
La Grande vetrata di San Zanipolo: acquisizioni e problemi aperti a trent’anni dalla mostra al Museo Correr
No full textIl contributo offre un succinto consuntivo degli studi e delle problematiche aperte sulla celebre “grande vetrata” della chiesa dei Santi Giovanni e Paolo a Venezia a trent’anni dalla mostra realizzata in occasione dell’ultimo restauro. Nell’occasione si propone per la prima volta l’attribuzione a Giovanni Mansueti della parte superiore della vetrata, a lungo ritenuta di Bartolomeo Vivarini e oggetto di un vasto dibattito. Tale attribuzione consente di sostenere la sostanziale contemporaneità di esecuzione con la parte inferiore, firmata da Girolamo Mocetto. Di quest’ultimo si offre l’elenco ragionato di un numero cospicuo di opere su tavola di nuova attribuzione che aumentano in modo determinante il catalogo dell’artista finora not
Domenico Pasqualigo e la “leonessa” di Delo alla Porta da Tera dell’Arsenale di Venezia
Full text linkGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Variations on the Author
Full text link“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
Measuring the spin of spiral galaxies
No full textWe compute the angular momentum, the spin parameter, and the related distribution function for dark matter halos hosting a spiral galaxy. We rely on scaling laws, inferred from observations, that link the properties of the galaxy to those of the host halo; we further assume that the dark matter has the same total specific angular momentum of the baryons. Our main results are as follows: (1) We find that the gas component of the disk significantly contributes to the total angular momentum of the system. (2) By adopting for the dark matter the observationally supported Burkert profile, we compute the total angular momentum of the disk and its correlation with the rotation velocity. (3) We find that the distribution function of the spin parameter λ peaks at a value of about 0.03, consistent with a no-major-merger scenario for the late evolution of spiral galaxies
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