4,829 research outputs found
Testing reflection features in 4U 1705-44 with XMM-Newton, BeppoSAX and RXTE in the hard and soft state
We use data of the bright atoll source 4U 1705-44 taken with XMM-Newton,
BeppoSAX and RXTE both in the hard and in the soft state to perform a
self-consistent study of the reflection component in this source. Although the
data from these X-ray observatories are not simultaneous, the spectral
decomposition is shown to be consistent among the different observations, when
the source flux is similar. We therefore select observations performed at
similar flux levels in the hard and soft state in order to study the spectral
shape in these two states in a broad band (0.1-200 keV) energy range, with good
energy resolution, and using self-consistent reflection models. These
reflection models provide a good fit for the X-ray spectrum both in the hard
and in the soft state in the whole spectral range. We discuss the differences
in the main spectral parameters we find in the hard and the soft state,
respectively, providing evidence that the inner radius of the optically thick
disk slightly recedes in the hard state.Comment: Accepted for publication in A&A, 20 pages, 12 figure
Magpie: towards a semantic web browser
Web browsing involves two tasks: finding the right web page and then making sense of its content. So far, research has focused on supporting the task of finding web resources through ‘standard’ information retrieval mechanisms, or semantics-enhanced search. Much less attention has been paid to the second problem. In this paper we describe Magpie, a tool which supports the
interpretation of web pages. Magpie offers complementary knowledge sources, which a reader can call upon to quickly gain access to any background knowledge relevant to a web resource. Magpie automatically associates an ontologybased
semantic layer to web resources, allowing relevant services to be invoked within a standard web browser. Hence, Magpie may be seen as a step towards a semantic web browser. The functionality of Magpie is illustrated using examples of how it has been integrated with our lab’s web resources
X-ray bursts and burst oscillations from the slowly spinning X-ray pulsar IGR J17480-2446 (Terzan 5)
The newly discovered 11 Hz accreting pulsar, IGR J17480-2446, located in the
globular cluster Terzan 5, has shown several bursts with a recurrence time as
short as few minutes. The source shows the shortest recurrence time ever
observed from a neutron star. Here we present a study of the morphological,
spectral and temporal properties of 107 of the bursts observed by the Rossi
X-ray Timing Explorer. The recurrence time and the fluence of the bursts
clearly anticorrelate with the increase of the persistent X-ray flux. The ratio
between the energy generated by the accretion of mass and that liberated during
bursts indicate that Helium is ignited in a Hydrogen rich layer. Therefore we
conclude that all the bursts shown by IGR J17480-2446 are Type-I X-Ray bursts.
Pulsations could be detected in all the brightest bursts and no drifts of the
frequency are observed within 0.25 Hz of the spin frequency of the neutron
star. These are also phase locked with respect to the pulsations observed
during the persistent emission and no rise of the rms associated to the pulse
frequency is observed during the burst. This behavior would favor a scenario
where the flash is ignited within a region which is consistent to be as large
as the neutron star surface.Comment: 11 pages, 7 figures and 2 tables. Accepted by MNRAS 2011 February 06.
Received 2011 January 07 ; in original form 2010 November 2
Atividade microbiana do solo sob diferentes cultivos irrigados em um Argissolo Vermelho Amarelo distrófico no Submédio São Francisco.
Este trabalho tem por objetivo avaliar a atividade biológica do solo sob diferentes cultivos com uso de irrigação e sua comparação com áreas de Caatinga. As amostras foram coletadas em novembro de 2006 em áreas com cultivo de manga, uva, culturas anuais, banana e em reserva de vegetação natural, no Campo Experimental da Embrapa Semi-¡rido no Distrito Irrigado de Bebedouro
Doses de nitrogênio sobre o acúmulo de nitrogênio na parte aérea e raiz de mudas de cafeeiro (Coffea arábica).
bitstream/item/69000/1/047-maciel-doses.pdfPublicado também no Cadernos de Agroecologia, v. 7, n.2, 2012
Horticultura agroecológica em escala familiar em Mato Grosso do Sul.
bitstream/item/66256/1/31283.pdfOrganizado por: Alberto Feiden, Milton Parron Padovan, Adalgiza Inês Campolim, Aurélio Vinícius Borsato, Ivo de Sá Motta, João Batista Catto, Tércio Jacques Fehlauer
Doses de nitrogênio sobre o crescimento de mudas de cafeeiro (Coffea arábica) em Itaquiraí, Mato Grosso do Sul.
bitstream/item/69029/1/048-maciel-doses.pdfPublicado também no Cadernos de Agroecologia, v. 7, n.2, 2012
Características químicas, físico-químicas e físicas de solos e o estado nutricional de cafeeiros que estão sob contínua aplicação de dejetos suínos.
- …