863 research outputs found
The Spin of the Black Hole Microquasar XTE J1550-564 via the Continuum-Fitting and Fe-Line Methods
We measure the spin of XTE J1550-564 in two ways: by modelling the thermal
continuum spectrum of the accretion disc, and independently by modeling the
broad red wing of the reflection fluorescence Fe-K line. We find that the spin
measurements conducted independently using both leading methods are in
agreement with one another. For the continuum-fitting analysis, we use a data
sample consisting of several dozen RXTE spectra, and for the Fe-K analysis, we
use a pair of ASCA spectra from a single epoch. Our spin estimate for the black
hole primary using the continuum-fitting method is -0.11 < a* < 0.71 (90 per
cent confidence), with a most likely spin of a* = 0.34. In obtaining this
result, we have thoroughly explored the dependence of the spin value on a wide
range of model-dependent systematic errors and observational errors; our
precision is limited by uncertainties in the distance and orbital inclination
of the system. For the Fe-line method, our estimate of spin is a* =
0.55(+0.15,-0.22). Combining these results, we conclude that the spin of this
black hole is moderate, a* = 0.49(+0.13,-0.20), which suggests that the jet of
this microquasar is powered largely by its accretion disc rather than by the
spin energy of the black hole.Comment: 19 pages, 15 figures, submitted to MNRAS, updated abstrac
Can lightning be a noise source for a spherical gravitational wave antenna?
The detection of gravitational waves is a very active research field at the
moment. In Brazil the gravitational wave detector is called Mario SCHENBERG.
Due to its high sensitivity it is necessary to model mathematically all known
noise sources so that digital filters can be developed that maximize the
signal-to-noise ratio. One of the noise sources that must be considered are the
disturbances caused by electromagnetic pulses due to lightning close to the
experiment. Such disturbances may influence the vibrations of the antenna's
normal modes and mask possible gravitational wave signals. In this work we
model the interaction between lightning and SCHENBERG antenna and calculate the
intensity of the noise due to a close lightning stroke in the detected signal.
We find that the noise generated does not disturb the experiment significantly.Comment: 5 pages, 6 figure
Weekly epirubicin for breast cancer with liver metastases and abnormal liver biochemistry.
Thirty-six consecutive patients with breast cancer and liver metastases with abnormal liver biochemistry were treated with epirubicin 25 mg m-2 i.v. weekly. No dose modification was made for abnormal liver biochemistry, but dose intensity was adjusted by delaying treatment according to myelosuppression. The UICC overall response rate according to UICC criteria was 11/36 (30%) and median response duration was 27 weeks. Liver biochemistry improved in a further seven patients. Treatment was well tolerated. Epirubicin given in this way is effective in patients with breast cancer and liver metastases. An initial deterioration in liver biochemistry may occur before there is a response to epirubicin
Preliminary results of the use of urinary excretion of pyridinium crosslinks for monitoring metastatic bone disease.
The collagen crosslinks, pyridinoline and deoxypyridinoline, are recently described markers of the rate of bone resorption. The urinary excretion of these compounds, expressed as a ratio to urinary creatinine, has been measured using ion-pair reversed phase high-performance liquid chromatography in 20 patients receiving oral pamidronate for bone metastases from breast cancer. Before treatment the ratio of pyridinoline and deoxypyridinoline to creatinine in urine (UPCR and UdPCR respectively) were each above normal in 16/20 (80%) patients. Urinary calcium excretion (UCCR) was elevated in 15/20 (75%). There was a strong correlation between UPCR and UdPCR, but neither of the crosslink measurements correlated well with UCCR. Urinary excretion of all three indices of bone resorption fell significantly during pamidronate treatment. The median values after 4 weeks treatment were 63% of baseline for UPCR, 45% for UdPCR and 26% for UCCR. From this preliminary study urinary pyridinoline and deoxypyridinoline excretion appear to be promising markers of bone resorption in advanced malignancy. Their role in response assessment and the advantages over UCCR measurements merit further study
A phase II, multicentre, UK study of vinorelbine in advanced breast cancer.
Thirty-four evaluable patients were treated with vinorelbine, a novel, semisynthetic vinca alkaloid, as first-line chemotherapy for advanced breast cancer. They received vinorelbine 25 mg m-2 i.v. given weekly for a maximum of 16 cycles. Two patients achieved a complete remission and 15 a partial remission, giving a response rate of 17/34 (50%; 95% CI of 34-66%); median response duration was 5.8 months. The median progression-free interval was 4.4 months and median survival 9.9 months. Treatment was generally well tolerated. Fatigue was the most common side-effect. The main reason for dose adjustments was myelosuppression; 68% of patients had WHO grade 3 or 4 neutropenia and there was one death attributed to neutropenic sepsis. Nausea/vomiting and neuropathy were mild and alopecia was uncommon. This study confirms vinorelbine as a highly active, well-tolerated agent in advanced breast cancer worthy of evaluation in combination chemotherapy regimens
Prednisolone improves the response to primary endocrine treatment for advanced breast cancer.
Two hundred and twenty patients with progressive advanced breast cancer were given primary endocrine treatment (PET) according to menstrual status. Pre-menopausal patients received ovarian irradiation (O) and post-menopausal tamoxifen 10 mg bd (T). Patients were randomised to receive either no additional treatment or prednisolone 5 mg bd (P). Similar results were observed in each menstrual subgroup. In 194 evaluable patients, the response to PET + P was 49% and to PET alone 30% (P less than 0.01). P increased the median duration of response from 9 to 14 months (P less than 0.002) and the median time to disease progression from 5 to 9 months (P less than 0.001). Response to P after O or T alone occurred in only 2/62 (3%). Median survival in patients randomised to receive P at the outset of PET was prolonged by 4 months (P less than 0.05). The addition of P significantly improves the response to O or T in the treatment of advanced breast cancer
Multivariable nonlinear advanced control of copolymerization processes
A reliable multivariable model of a process is a fundamental prerequisite for the design of an efficient control strategy. Though, such a model is often very hard to obtain via a first-principles approach. The development of two fuzzy model-based multivariable nonlinear predictive control schemes and their implementation on a copolymerization process are described in this paper. Multi-input/single-output models are developed using fuzzy logic and combined to form a parallel system model for simulation and online prediction. The behavior of the outlined controllers were compared to the dynamic matrix control (DMC) and to a typical nonlinear model-based predictive control (NMPC) for regulatory problem and the obtained results showed the effectiveness of the proposed structures
Sedimentação da Lagoa Itapeva, RS, Brasil
Hydrodynamic factors that control sedimentation in the Itapeva Lake were assessed on the granulometric distribution map generated by the Pejrup’s diagram and by the analysis of the hydrodynamic action, which results from the waves in the lacustrine body. The texture patterns of bottom samples showed that there is significant hydrodynamic energy in the sedimentation process: the sand fraction prevails in the submerged margins whereas grain size decreases, from coarse silt to fine silt, moved towards the center. The content of organic matter also shows this pattern, with a steady increase in the central area of the lacustrine body and near the mouths of the Três Forquilhas and Cardoso rivers. The main processes that determine sedimentation are mainly controlled by the amount of fluvial sediment, which is redistributed by the action of waves and currents resulting from the action of winds. The concentration of clay-sized grains is not very significant not only because there is low input by the rivers, but also because the wave agitation avoid this granulometric class from depositing on the lacustrine bottom. Fine sediment in the deepest spots and in the most sheltered areas shows the influence of less effective currents that enable deposition in these areas.Os fatores hidrodinâmicos que controlam a sedimentação na Lagoa Itapeva foram avaliados através do mapa de distribuição granulométrica gerado a partir do diagrama de Pejrup e da análise da ação hidrodinâmica induzida pelas ondas no corpo lacustre. Os padrões texturais das amostras de fundo indicaram a presença de significativa energia hidrodinâmica atuante no processo de sedimentação, com predomÃnio da fração arenosa nas margens submersas e granodecrescência para tamanhos silte grosso a fino em direção ao centro. O teor de matéria orgânica também apresenta este padrão, com aumento gradativo na área central do corpo lacustre e nas proximidades das desembocaduras dos rios Três Forquilhas e Cardoso. Os principais processos que condicionam a sedimentação na lagoa são controlados pelo aporte de sedimentos fluviais, redistribuÃdos pela ação das ondas e correntes induzidas pela ação dos ventos. A concentração de grãos tamanho argila é pouco significativa, devido à baixa inserção pelos rios, além da agitação gerada por ondas sobre o piso lacustre, que dificulta a deposição desta classe granulométrica. A presença de sedimentos finos nos locais mais profundos e nas áreas mais abrigadas indica a influência de correntes menos efetivas, permitindo a deposição nestes locais
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