978 research outputs found
Spectral Fits to the 1999 Aql X-1 Outburst Data
We present analysis and spectral fits of the RXTE data from the May/June 1999
outburst of Aql X-1. These data include observations in the rising portion of
the hard state, in the soft state, and in the falling portion of the hard
state. We show that the data can be fit by a purely thermal Comptonization
model for all the observations, but that more complicated models cannot be
ruled out. Up to 60% of the corona's power in the soft state may be injected
into non-thermal electrons. The soft state data show approximately constant
optical depth and coronal temperatures over a range of in luminosity,
while they show evidence for a reduction of seed photon temperature with
reduced luminosity and indicate that the characteristic size of the seed photon
emitting region is roughly constant throughout the soft state. The hard state
before the soft state shows a higher luminosity, higher optical depth, and
lower electron temperature than the hard state after the soft state. We find a
reduction of the hard (30-60 keV) X-ray flux during a type I burst and show
that it requires a total corona energy reservoir of less than
ergs.Comment: 10 pages, 7 figues, accepted to A+
Tracing the power-law component in the energy spectrum of black hole candidates as a function of the QPO frequency
We investigated the relation between the centroid frequency of the
quasi-periodic oscillation observed in the power density spectra of a sample of
galactic black-hole candidates with the power-law photon index obtained from
spectral fits. Our aim is to avoid inner accretion disk radius determination
directly from spectral fits, given the uncertainties of the absolute values
obtained in that way, but to base our analysis on the likely association of QPO
frequency to a characteristic radius. We used archival RXTE data of GRS
1915+105 and published parameters for GRO 1655-40, XTE J1550-564, XTE J1748-288
and 4U 1630-47. While for low values of the QPO frequency, the two parameters
are clearly correlated for each source, there is evidence for a turnoff in the
correlation above a characteristic frequency, different for different sources.
We discuss the possible nature of this turnoff.Comment: 11 pages, 10 figures. Accepted for publication on Astronomy &
Astrophysic
PIBID música e prática pedagógico-musical: experiências de ensino envolvendo cotidiano e prática musical
Anais do II Seminário Seminário Estadual PIBID do Paraná: tecendo saberes / organizado por Dulcyene Maria Ribeiro e Catarina Costa Fernandes — Foz do Iguaçu: Unioeste; Unila, 2014O trabalho apresenta a experiência de atuação no subprojeto de Música do PIBID da
Universidade Estadual de Ponta Grossa, realizado em uma escola da rede pública de ensino do
municÃpio, e tem como principal objetivo discutir duas atividades realizadas, sendo uma sobre ‘Rock e
os elementos formais do som’ e a outra referente a uma experiência de prática musical com os alunos,
que integrava canto, violão, percussão e flauta. Foi possÃvel avaliar que a maioria dos alunos
conseguiu assimilar o conteúdo mais efetivamente por ter sido trabalhado com recursos que fazem
parte do seu cotidiano e por ser um contexto mais próximo da sua realidade auditiva. Os momentos de
prática musical proporcionaram reflexões sobre a importância do planejamento no momento da
realização das atividades e a necessidade deste ser flexÃvel e estar elaborado detalhadament
Accretion flow behaviour during the evolution of the Quasi Periodic Oscillation Frequency of XTE J1550-564 in 1998 outburst
Low and intermediate frequency quasi-periodic oscillations (QPOs) are thought
to be due to oscillations of Comptonizing regions or hot regions embedded in
Keplerian discs. Observational evidence of evolutions of QPOs would therefore
be very important as they throw lights on the dynamics of the hotter region.
Our aim is to find systems in which there is a well-defined correlation among
the frequencies of the QPOs over a range of time so as to understand the
physical picture. In this paper, we concentrate on the archival data of XTE
J1550-564 obtained during 1998 outburst, and study the systematic drifts during
the rising phase from the 1998 September 7 to the 1998 September 19, when the
QPO frequency increased monotonically from 81mHz to 13.1Hz. Immediately after
that, QPO frequency started to decrease and on the 1998 September 26, the QPO
frequency became 2.62Hz. After that, its value remained almost constant. This
frequency drift can be modelled satisfactorily with a propagatory oscillating
shock solution where the post-shock region behaves as the Comptonized region.
Comparing with the nature of a more recent 2005 outburst of another black hole
candidate GRO 1655-40, where QPOs disappeared at the end of the rising phase,
we conjecture that this so-called `outburst' may not be a full-fledged
outburst.Comment: 15 pages, 6 figure
The long-term effect of complex regional pain syndrome type 1 on disability and quality of life after foot injury
PURPOSE: To study the long-term evolution of patients with lower-limb Complex Regional Pain Syndrome (CRPS), focusing on functional and proprioceptive aspects and quality of life. METHODS: In 20 patients suffering from chronic distal lower-limb CRPS diagnosed using Budapest criteria, we assessed joint position sense and strength of the knee muscles at the CRPS and unaffected leg, functional exercise capacity, pain, CRPS severity score, quality of life and kinesiophobia. Similar assessments were performed in 20 age-matched controls. RESULTS: The joint position performance (at 45°) was significantly lower for the CRPS leg as compared to controls. The knee extensor strength of the CRPS leg was significantly reduced as compared to the unaffected leg (−27%) and controls (−42%). CRPS patients showed significantly reduced performance at the 6 min-walk test as compared to their age group predicted value and controls. Patients suffering from CRPS for 3.8 years in average still exhibit high pain, severity and kinesiophobia scores. CONCLUSIONS: Long-term deficits in strength and proprioceptive impairments are observed at the knee joint of the CRPS leg. This persistent functional disability has significant repercussions on the quality of life. We highlight the importance of including strength and proprioceptive exercises in the therapeutic approaches for CPRS patients
QPO Frequency - Color Radius Connection in GRS 1915+105: a Possible Turnover supporting AEI predictions
It is widely believed that the low frequency quasi-periodic X-ray
oscillations observed in microquasars are correlated to, but do not originate
at, the physical radius of the inner edge of the accretion disk. Models
relating the QPO frequency and color radius are hindered by observations
showing contradicting trend correlations between the microquasars GRO 1655-40,
XTE J1550-564 and GRS 1915+105. The first shows a negative correlation and the
latter two a positive one. By taking into account relativistic rotation in the
accretion disk, the Accretion-Ejection Instability (AEI) model predicts a
turnover in the frequency-radius relationship, and has been successfully
compared with observations of GRO J1655-40 and GRS 1915+105. We present further
evidence supporting the AEI model prediction by using observations of the
microquasar GRS 1915+105. By combining a data set including -, -
and -class X-ray light curves, we observe positive, negative and null
correlations in the frequency-radius relationship. This is the first time a
single source has shown a possible inversion in the QPO frequency-color radius
curve predicted by the AEI model
An Integration Testing Facility for the CERN Accelerator Controls System
A major effort has been invested in the design, development, and deployment of the LHC Control System. This large control system is made up of a set of core components and dependencies, which although tested individually, are often not able to be tested together on a system capable of representing the complete control system environment, including hardware. Furthermore this control system is being adapted and applied to CERN's whole accelerator complex, and in particular for the forthcoming renovation of the PS accelerators. To ensure quality is maintained as the system evolves, and toimprove defect prevention, the Controls Group launched a project to provide a dedicated facility for continuous, automated, integration testing of its core components to incorporate into its production process. We describe the project, initial lessons from its application, status, and future directions
A Low/Hard State Outburst of XTE J1550-564
We present the results of the analysis of 11 RXTE/PCA observations of the
January 2002 outburst of the black-hole transient XTE J1550-564. The outburst
was rather short, with an e-folding time of ~11 days in the PCA band 3-25 keV.
The source was seen in an extreme low/hard state. The energy spectra could be
fitted with a power law slightly steepening (Gamma ~ 1.4 to ~1.5) in time, with
a high-energy cutoff decreasing from ~300 keV to ~100 keV and some additional
features between 6 and 7 keV, while the 3-150 keV flux decreased by a factor of
17. The power spectra were fitted with two broad Lorentzian components, whose
characteristic frequencies decreased with the source flux, and whose fractional
rms contribution was rather constant. The timing parameters derived can be
identified with those observed in other systems. These results show that,
although during previous, more luminous, outbursts, a very complex behavior was
observed, at low luminosities XTE J1550-564 behaves in a way comparable to most
Black-Hole Candidates.Comment: Accepted for publication on Astronomy and Astrophysic
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