| 1. |
- Crenshaw, D. M., et al.
(författare)
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Multiwavelength observations of short-timescale variability in NGC 4151. I. Ultraviolet observations
- 1996
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 470:1, s. 322-335335
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Tidskriftsartikel (refereegranskat)abstract
- Presents the results of an intensive ultraviolet monitoring campaign on the Seyfert 1 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 Aring went through four significant and well-defined ldquoeventsrdquo of duration 2-3 days during the continuous-monitoring period. The authors 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
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| 2. |
- Edelson, R. A., et al.
(författare)
-
Multiwavelength observations of short-timescale variability in NGC 4151. IV. Analysis of multiwavelength continuum variability
- 1996
-
Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 470:1, s. 364-377377
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Tidskriftsartikel (refereegranskat)abstract
- For pt.III see ibid., vol.470, no.1, p.349-63 (1996). Combines data from the three preceding papers in order to analyze the multi wave-band variability and spectral energy distribution of the Seyfert 1 galaxy NGC 4151 during the 1993 December 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 gamma-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 to 6900 Aring. These data do not probe extreme ultraviolet (1200 Aring to 0.1 keV) or hard X-ray (250 keV) variability. The phase differences between variations in different bands were consistent with zero lag, with upper limits of lsim0.15 day between 1275 Aring and the other ultraviolet bands, lsim0.3 day between 1275 Aring and 1.5 keV, and lsim1 day between 1275 and 5125 Aring. These tight limits represent more than an order of magnitude improvement over those determined in previous multi-wave-band 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 (ales-2.5)
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| 3. |
- Hursti, T J, et al.
(författare)
-
Impact of tumour burden on chemotherapy-induced nausea and vomiting.
- 1996
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Ingår i: British Journal of Cancer. - : Springer Science and Business Media LLC. - 0007-0920 .- 1532-1827. ; 74:7, s. 1114-1119
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Tidskriftsartikel (refereegranskat)abstract
- We investigated how residual tumour burden after cytoreductive surgery was related to the occurrence of acute and delayed nausea and vomiting in 101 ovarian cancer patients receiving their first chemotherapy course. The anti-emetic treatment included ondansetron combined with dexamethasone or placebo. After chemotherapy all patients received ondansetron only for 5 days. Two categories of tumour burden (TB) were formed according to the diameter of the greatest residual tumour (< 2 cm = minimal TB and > or = 2 cm = large TB). Self-reports of nausea and vomiting were obtained for 15 days. Other potential predictor variables were assessed and included in multivariate analyses. Patients with large compared with minimal TB had more delayed emesis, especially on days 2-7. They also had more acute nausea. The aggravating effect associated with large residual TB was more evident in patients > or = 55 years. During the second week after the chemotherapy the occurrence of nausea was higher in patients > or = 55 years than in those < 55 years. This was seen primarily in patients with large residual TB. Predictors for no delayed emesis at all were anti-emetic treatment with dexamethasone, minimal tumour burden, low neuroticism and no history of motion sickness. The increased risk of "persistent' delayed nausea and vomiting seen in older patients with large tumour burden may have important clinical implications and warrants further attention.
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| 4. |
- Hursti, Timo J, et al.
(författare)
-
Impact of tumour burden on chemotherapy-induced nausea and vomiting
- 1996
-
Ingår i: BRITISH JOURNAL OF CANCER. - : STOCKTON PRESS. - 0007-0920. ; 74:7, s. 1114-1119
-
Tidskriftsartikel (refereegranskat)abstract
- We investigated how residual tumour burden after cytoreductive surgery was related to the occurrence of acute and delayed nausea and vomiting in 101 ovarian cancer patients receiving their first chemotherapy course. The anti-emetic treatment included ond
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| 5. |
- Peterson, Curt, et al.
(författare)
-
Single high-dose dexamethasone improves the effect of ondansetron on acute chemotherapy-induced nausea and vomiting but impairs the control of delayed symptoms.
- 1996
-
Ingår i: Supportive Care in Cancer. - 0941-4355 .- 1433-7339. ; 4:6, s. 440-446
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Tidskriftsartikel (refereegranskat)abstract
- The introduction of serotonin receptor (5-HT3) antagonists has improved the control of acute nausea and vomiting induced by cancer chemotherapy, but they seem to have little or no effect on delayed symptoms. Corticosteroids are known to reduce both acute and delayed nausea and vomiting. The aim of the present study was to test the hypothesis that a single high dose of dexamethasone (20 mg), a long-acting corticosteroid, given after cisplatin and in addition to ondansetron (8 mg three times a day), would enhance the control of both acute and delayed nausea and vomiting. A group of 104 chemotherapy-naive ovarian cancer patients, scheduled for at least three cycles of combination chemotherapy including cisplatin (50 mg/m2), were randomly allocated to receive either dexamethasone or placebo in addition to ondansetron. Two-thirds of the patients received doxorubin and melphalan on the day before cisplatin and 1/3 received doxorubicin immediately before cisplatin. Unexpectedly we found, in all three chemotherapy cycles, that patients receiving dexamethasone suffered from more delayed nausea and vomiting than patients receiving placebo. In patients with no acute nausea or vomiting, the boomerang effect of dexamethasone could be seen on the first day after chemotherapy. In a follow-up study on 5 patients not included in the randomized trial, dexamethasone induced a pronounced reduction in urinary cortisol excretion on the day after chemotherapy with a return to normal excretion on day 2. It is concluded that a single high dose of dexamethasone does not seem appropriate for controlling delayed nausea and vomiting.
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| 6. |
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| 7. |
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