RXTE Spectral Observations of the 1996-97 Outburst of the Microquasar GRO J1655-40

Excellent coverage of the entire 16-month 1996-97 outburst cycle of GRO J1655-40 was provided by RXTE. We present a full spectral analysis of these data, which includes 52 PCA spectra from 2.5-20 keV and HEXTE spectra above 20 keV. We also include a nearly continuous ASM light curve with several intensity measurements per day. The data are interpreted in the context of the multicolor blackbody disk/power-law model. The source is observed in the very high, high/soft, and low/hard outburst states. During the very high state, the source exhibits intense hard flares on time scales of hours to days which are correlated with changes in both the fitted temperature and radius of the inner accretion disk. During the high/soft state, the spectrum is dominated by the soft thermal emission from the accretion disk with spectral parameters that suggest approximately constant inner disk radius and temperature. We find that a tight relationship exists between the observed inner radius of the disk and the flux in the power-law component. During intense hard flares, the inner disk radius is observed to decrease by as much as a factor of three on a time scale of days. The apparent decrease of the inner disk radius observed during the flares may be due to the failure of the multicolor disk model caused by a steepening of the radial temperature profile in the disk coupled with increased spectral hardening and not physical changes of the inner disk radius. Assuming that our spectral model is valid during periods of weak power-law emission, our most likely value for the inner disk radius implies a* < 0.7. Such a low value for the black hole angular momentum is inconsistent with the relativistic frame dragging and the `diskoseismic' models as interpretations for the 300 Hz X-ray QPO seen during some of these RXTE observations.Comment: 34 pages including 9 figures and 3 tables. Accepted for publication in the Astrophysical Journal. Our interpretation of the data and the main conclusions have been significantly revise

Antireflective photonic structure for coherent nonlinear spectroscopy of single magnetic quantum dots

This work presents epitaxial growth and optical spectroscopy of CdTe quantum dots (QDs) in (Cd,Zn,Mg)Te barriers placed on the top of (Cd,Zn,Mg)Te distributed Bragg reflector. The formed photonic mode in our half-cavity structure permits to enhance the local excitation intensity and extraction efficiency of the QD photoluminescence, while suppressing the reflectance within the spectral range covering the QD transitions. This allows to perform coherent, nonlinear, resonant spectroscopy of individual QDs. The coherence dynamics of a charged exciton is measured via four-wave mixing, with the estimated dephasing time $T_2=(210\,\pm\,40)$ ps. The same structure contains QDs doped with single Mn$^{2+}$ ions, as detected in photoluminescence spectra. Our work therefore paves the way toward investigating and controlling an exciton coherence coupled, via $s$,$p$-$d$ exchange interaction, with an individual spin of a magnetic dopant.Comment: 6 pages, 5 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

A Common Software Configuration Management System for CERN SPS and LEP Accelerators and Technical Services

Software configuration management activities are crucial to assure the integrity of current operational and the quality of new software either being developed at CERN or outsourced. The functionality of the present management system became insufficient with large maintenance overheads. In order to improve our situation, a new software configuration management system has been set up. It is based on Razor, a commercial tool, which supports the management of file versions and operational software releases, along with integrated problem reporting capabilities. In addition to the basic tool functionality, automated procedures were custom made, for the installation and distribution of operational software. Policies were developed and applied over the software development life cycle to provide visibility and control. The system ensures that, at all times, the status and location of all deliverable versions are known, the state of shared objects is carefully controlled and unauthorised changes prevented. It provides a managed environment for software development, in various domains of the SPS and LEP CERN accelerators, and the technical services, automating code and lifecycle management. This paper outlines the reasons for selecting the chosen tool, the implementation of the system, the problems solved and the final goals achieved

X-ray Nova XTE J1550-564: RXTE Spectral Observations

Excellent coverage of the 1998 outburst of the X-ray Nova XTE J1550-564 was provided by the Rossi X-ray Timing Explorer. XTE J1550-564 exhibited an intense (6.8 Crab) flare on 1998 September 19 (UT), making it the brightest new X-ray source observed with RXTE. We present a spectral analysis utilizing 60 Proportional Counter Array spectra from 2.5-20 keV spanning 71 days, and a nearly continuous All Sky Monitor light curve. The spectra were fit to a model including multicolor blackbody disk and power-law components. XTE J1550-564 is observed in the very high, high/soft, and intermediate canonical outburst states of Black Hole X-ray Novae.Comment: 14 pages including 1 table and 4 figures, Accepted to ApJ Letter

Characterizing the QPO Behavior of the X-ray Nova XTE J1550--564

For all 209 RXTE observations of the X-ray nova XTE J1550-564 during its major outburst of 1998-1999, we have analyzed the X-ray power spectra, phase lags, and coherence functions. The phase lags and coherence measures are used to distinguish three types of low-frequency QPOs (one more than those reported by Wijnands, Homan, & van der Klis 1999). For the most common type, the phase lag is correlated with both the QPO frequency and the amplitude. The physical significance of the QPO types is evident in the relationships between QPO properties and the apparent temperature and flux from the accretion disk. There is also a clear pattern in how the QPO types relate to the presence of high-frequency QPOs. In general, both the amplitude and the Q value (freq./FWHM) of low-frequency QPOs decrease as the high-frequency oscillations increase in frequency (100 to 284 Hz) and in Q value. We speculate that the antagonism between low-frequency and high-frequency QPOs arises from competing structures in a perturbed accretion disk. However, we find that the frequencies of slow ( 100 Hz) QPOs are not correlated. In addition, we encounter systematic problems in attempting to reliably compare the QPO frequencies with broad features in the power continuum, since there are a variable number of such features in the power spectra. These results cast some doubt on the reported global relationship between QPOs from neutrons stars and those from black hole systems.Comment: 27 pages, including 2 tables and 7 figures. submitted to ApJ; rewrite of astro-ph/000421