93 research outputs found
Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. VI. Variability of NGC 3783 from ground-based data
The Seyfert 1 galaxy NGC 3783 was intensely monitored between 1991 December
and 1992 August. We present the results from the ground-based observations in
the optical and near-IR, which complement the data-set from the IUE, discussed
elsewhere. Spectroscopic and photometric data from many observatories were
combined in order to obtain well sampled light curves of the continuum and of
H-Beta. During the campaign the source varied significantly. The light curves
of the optical continuum and of H-Beta are similar to those obtained with the
IUE. The near-IR flux did not vary significantly except for an increase at the
end of the campaign. The optical continuum and the flux of H-Beta lag the UV
continuum by 1 day or less and by 8 days respectively. These results confirm
that the continuum variations are simultaneous or have a very small lag across
the entire UV-optical range, and that the lines of NGC 3783 respond to ionizing
continuum variations with less delay than those of NGC 5548. As in NGC 5548,
the lag of H-Beta is greater than those of the high ionization lines.Comment: 34 pages in LaTeX, 7 postscript figures available on request from
[email protected] or 37907::stirpe, BAP#10-1993-035-OA
Multiwavelength observations of short time-scale variability in NGC 4151. IV. Analysis of multiwavelength continuum variability
This paper combines data from the three preceding papers in order to analyze
the multi-waveband variability and spectral energy distribution of the
Seyfert~1 galaxy NGC~4151 during the December 1993 monitoring campaign. The
source, which was near its peak historical brightness, showed strong,
correlated variability at X-ray, ultraviolet, and optical wavelengths. The
strongest variations were seen in medium energy (1.5~keV) X-rays, with a
normalized variability amplitude (NVA) of 24\%. Weaker (NVA = 6\%) variations
(uncorrelated with those at lower energies) were seen at soft -ray
energies of 100~keV. No significant variability was seen in softer
(0.1--1~keV) X-ray bands. In the ultraviolet/optical regime, the NVA decreased
from 9\% to 1\% as the wavelength increased from 1275~\AA\ to 6900~\AA. These
data do not probe extreme ultraviolet (1200~\AA\ to 0.1~keV) or hard X-ray
(2--50~keV) variability. The phase differences between variations in different
bands were consistent with zero lag, with upper limits of \ls0.15~day between
1275~\AA\ and the other ultraviolet bands, \ls0.3~day between 1275~\AA\ and
1.5~keV, and \ls1~day between 1275~\AA\ and 5125~\AA. These tight limits
represent more than an order of magnitude improvement over those determined in
previous multi-waveband AGN monitoring campaigns. The ultraviolet fluctuation
power spectra showed no evidence for periodicity, but were instead well-fitted
with a very steep, red power-law ().
If photons emitted at a ``primary" waveband are absorbed by nearby material
and ``reprocessed" to produce emission at a secondary waveband, causality
arguments require that variations in the secondary band follow those in the
primary band. The tight interband correlation and limits on the ultraviolet andComment: 35 pages, LaTeX (including aaspp4), including 7 PostScript figures;
To appear in the ApJ (October 20, 1996) Vol. 47
A phase II study of docetaxel in patients with metastatic squamous cell carcinoma of the head and neck
This study was designed to evaluate the activity, safety and tolerance of docetaxel (D) in a selected population with metastatic squamous cell carcinoma of the head and neck (SCCHN). Twenty-four patients with no prior palliative therapy were enrolled and received D 100 mg mâ2 by 1 h of infusion, every 3 weeks. All but two patients had been evaluated for efficacy on lung metastatic sites. No prophylactic administration of anti-emetics or growth factors was given. A pharmacokinetic study was performed in 22 patients. Twenty-one patients were assessable for response and 24 for toxicity. One hundred and four cycles were administered with a median of 4.5 (range 1â9) per patient. The median cumulative dose was 449 mg mâ2. Partial responses were achieved in five patients with a median duration of 18.7 weeks (range 13.1â50.3). The overall response rate was 20.8% with a median duration of 11.0 weeks (range 2.4â52.6). The most frequent side-effect was neutropenia (79.2% grade IV) but with a short duration (median 4 days) and no febrile neutropenia. The incidence of moderate/severe fluid retention was 29.2% with one treatment discontinuation. Other toxicities (all grades) were common (skin 75%, asthenia 50%, infection 29.2%, nausea 16.7%, diarrhoea 12.5%, stomatitis 16.7%, vomiting 8.3% and HSR 8.3%). A mean clearance of 19.6 l hâ1 mâ2 and an area under the curve of 6.00 ÎŒg mlâ1 hâ1 was found in the pharmacokinetic analysis. Docetaxel is active in this selected population with metastatic SCCHN, with a good tolerance. © 1999 Cancer Research Campaig
Multiwavelength observations of short time-scale variability in NGC 4151. I. Ultraviolet observations
We present the results of an intensive ultraviolet monitoring campaign on the
Seyfert 1 galaxy NGC 4151, as part of an effort to study its short time-scale
variability over a broad range in wavelength. The nucleus of NGC 4151 was
observed continuously with the {\it International Ultraviolet Explorer} (IUE)
for 9.3 days, yielding a pair of LWP and SWP spectra every 70 minutes,
and during four-hour periods for 4 days prior to and 5 days after the
continuous monitoring period. The sampling frequency of the observations is an
order of magnitude higher than that of any previous UV monitoring campaign on a
Seyfert galaxy.
The continuum fluxes in bands from 1275 \AA\ to 2688 \AA\ went through four
significant and well-defined ``events'' of duration 2 -- 3 days during the
continuous monitoring period. We find that the amplitudes of the continuum
variations decrease with increasing wavelength, which extends a general trend
for this and other Seyfert galaxies to smaller time scales (i.e., a few days).
The continuum variations in all of the UV bands are {\it simultaneous} to
within an accuracy of about 0.15 days, providing a strict constraint on
continuum models. The emission-line light curves show only one major event
during the continuous monitoring (a slow rise followed by a shallow dip), and
do not correlate well with continuum light curves over the (short) duration of
the campaign, because the time scale for continuum variations is apparently
smaller than the response times of the emission lines.Comment: 39 pages, LaTeX, including 7 PostScript figures; To appear in the ApJ
(October 20, 1996) Vol. 47
Obesity indexes and total mortality among elderly subjects at high cardiovascular risk: The PREDIMED study
Different indexes of regional adiposity have been proposed for identifying persons at higher risk of death. Studies specifically assessing these indexes in large cohorts are scarce. It would also be interesting to know whether a dietary intervention may counterbalance the adverse effects of adiposity on mortality.
METHODS:
We assessed the association of four different anthropometric indexes (waist-to-height ratio (WHtR), waist circumference (WC), body mass index (BMI) and height) with all-cause mortality in 7447 participants at high cardiovascular risk from the PREDIMED trial. Forty three percent of them were men (55 to 80 years) and 57% were women (60 to 80 years). All of them were initially free of cardiovascular disease. The recruitment took place in 11 recruiting centers between 2003 and 2009.
RESULTS:
After adjusting for age, sex, smoking, diabetes, hypertension, intervention group, family history of coronary heart disease, and leisure-time physical activity, WC and WHtR were found to be directly associated with a higher mortality after 4.8 years median follow-up. The multivariable-adjusted HRs for mortality of WHtR (cut-off points: 0.60, 0.65, 0.70) were 1.02 (0.78-1.34), 1.30 (0.97-1.75) and 1.55 (1.06-2.26). When we used WC (cut-off points: 100, 105 and 110 cm), the multivariable adjusted Hazard Ratios (HRs) for mortality were 1.18 (0.88-1.59), 1.02 (0.74-1.41) and 1.57 (1.19-2.08). In all analyses, BMI exhibited weaker associations with mortality than WC or WHtR. The direct association between WHtR and overall mortality was consistent within each of the three intervention arms of the trial.
CONCLUSIONS:
Our study adds further support to a stronger association of abdominal obesity than BMI with total mortality among elderly subjects at high risk of cardiovascular disease. We did not find evidence to support that the PREDIMED intervention was able to counterbalance the harmful effects of increased adiposity on total mortality.
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Multiwavelength Observations of Short-Timescale Variability in NGC 4151. I. Ultraviolet Observations
We present the results of an intensive ultraviolet monitoring campaign on the Seyfert I galaxy NGC 4151, as part of an effort to study its short-timescale variability over a broad range in wavelength. The nucleus of NGC 4151 was observed continuously With the International Ultraviolet Explorer for 9.3 days, yielding a pair of LWP and SWP spectra every ~70 minutes, and during 4 hr periods for 4 days Prior to and 5 days after the continuous-monitoring period. The sampling frequency of the observations is an order of magnitude higher than that of any previous UV monitoring campaign on a Seyfert galaxy. The continuum fluxes in bands from 1275 to 2688 A went through four significant and well-defined events of duration 2-3 days during the continuous-monitoring period. We find that the amplitudes of the continuum variations decrease with increasing wavelength, which extends a general trend for this and other Seyfert galaxies to smaller timescales (i.e., a few days). The continuum variations in all the UV bands are simultaneous to within an accuracy of ~0.15 days, providing a strict constraint on continuum models. The emission-line light curves show only one major event during the continuous monitoring (a slow rise followed by a shallow dip) and do not correlate well with continuum light curves over the short duration of the campaign, because the timescale for continuum variations is apparently smaller than the response times of the emission lines.Astronom
Empirically derived food patterns and the risk of total mortality and cardiovascular events in the predimed study
BACKGROUND & AIMS:
There is little evidence on post hoc-derived dietary patterns (DP) and all-cause mortality in Southern-European populations. Furthermore, the potential effect modification of a DP by a nutritional intervention has not been sufficiently assessed. We assessed the association between a posteriori defined baseline major DP and total mortality or cardiovascular events within each of the three arms of a large primary prevention trial (PREDIMED) where participants were randomized to two active interventions with Mediterranean-type diets or to a control group (allocated to a low-fat diet).
DESIGN:
We followed-up 7216 participants for a median of 4.3 years. A validated 137-item food-frequency questionnaire was administered. Baseline DP were ascertained through factor analysis based on 34 predefined groups. Cox regression models were used to estimate multivariable-adjusted hazard ratios (HR) for cardiovascular disease (CVD) or mortality across quartiles of DP within each of the three arms of the trial.
RESULTS:
We identified two major baseline DP: the first DP was rich in red and processed meats, alcohol, refined grains and whole dairy products and was labeled Western dietary pattern (WDP). The second DP corresponded to a "Mediterranean-type" dietary pattern (MDP). During follow-up, 328 participants died. After controlling for potential confounders, higher baseline adherence to the MDP was associated with lower risk of CVD (adjusted HR for fourth vs. first quartile: 0.52; 95% CI (Confidence Interval): 0.36, 0.74; p-trend <0.001) and all-cause mortality (adjusted HR: 0.53; 95% CI: 0.38, 0.75; p-trend <0.001), regardless of the allocated arm of the trial. An increasing mortality rate was found across increasing quartiles of the WDP in the control group (allocated to a low-fat diet), though the linear trend was not statistically significant (p = 0.098).
CONCLUSIONS:
Higher adherence to an empirically-derived MDP at baseline was associated with a reduced risk of CVD and mortality in the PREDIMED trial regardless of the allocated arm. The WDP was not associated with higher risk of mortality or cardiovascular events
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