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- 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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3. |
- Edelson, R. A., et al.
(författare)
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Multiwavelength observations of short-timescale variability in NGC 4151. IV. Analysis of multiwavelength continuum variability
- 1996
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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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5. |
- Halzen, F., et al.
(författare)
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From the first neutrino telescope, the antarctic muon and neutrino detector array AMANDA, to the IceCube observatory
- 1999
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Ingår i: Proceedings of the 26th International Cosmic Ray Conference, August 17-25, 1999, Salt Lake City : Invited, Rapporteur, and Highlight Papers. - : American Institute of Physics (AIP). ; , s. 428-431
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Konferensbidrag (refereegranskat)
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6. |
- Andres, E., et al.
(författare)
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AMANDA : Status, results and future
- 1999
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Ingår i: Proceedings, 8th International Workshop, Venice, Italy, February 23-26, 1999. Vol. 1, 2. ; , s. 63-79
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Konferensbidrag (refereegranskat)abstract
- We review the status of the AMANDA neutrino telescope. We present resultsobtained from the four-string prototype array AMANDA-B4 and describe themethods of track reconstruction and neutrino event separation. We give also firstresults of the analysis of the 10-string detector AMANDA-B10, in particular onatmospheric neutrinos and the search for magnetic monopoles. We sketch thefuture schedule on the way to a cube kilometer telescope at the South Pole,ICECUBE.
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8. |
- Andrés, E. C., et al.
(författare)
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The AMANDA neutrino telescope
- 1999
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Ingår i: Nuclear physics B, Proceedings supplements. - 0920-5632 .- 1873-3832. ; 77:1-3, s. 474-485
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Tidskriftsartikel (refereegranskat)abstract
- With an effective telescope area of order 104 m2 for TeV neutrinos, a threshold near ∼50 GeV and a pointing accuracy of 2.5 degrees per muon track, the AMANDA detector represents the first of a new generation of high energy neutrino telescopes, reaching a scale envisaged over 25 years ago. We describe early results on the calibration of natural deep ice as a particle detector as well as on AMANDA's performance as a neutrino telescope.
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9. |
- Barwick, S. W., et al.
(författare)
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Initial results from the AMANDA high-energy neutrino detector
- 1998
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Ingår i: High-energy physics. Proceedings, 29th International Conference, ICHEP'98, Vancouver, Canada, July 23-29, 1998. Vol. 1, 2. ; , s. 1447-1452
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Konferensbidrag (refereegranskat)
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10. |
- Erkens, U., et al.
(författare)
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Monitoring of active galactic nuclei. VI. The quasar Mrk 876
- 1995
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Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 296:1, s. 90-9898
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Tidskriftsartikel (refereegranskat)abstract
- For pt. V see ibid., vol. 285, no. 3, p. 857-67 (1994). We present the results of a 6 month monitoring campaign of Mrk 876, a low luminosity quasar with M absap-24. High resolution spectroscopy and direct imaging in the Johnson filters B, V, R, I was carried out in the first half of 1990. Line and continuum light curves are presented. Mrk 876 showed a decrease of 17% in the continuum over the whole observing period whereas the line flux of Hbeta and Halpha stayed constant. This implies, that the radius of the broad line region is larger than 6 light months. Coadded spectra of Hbeta and Halpha are presented which confirm an extreme asymmetry of the line profiles to the red. With respect to much earlier spectra the line profiles changed considerably
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11. |
- Wischnewski, R., et al.
(författare)
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The AMANDA neutrino detector
- 1999
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Ingår i: Nuclear physics B, Proceedings supplements. - : Elsevier. - 0920-5632 .- 1873-3832. ; 75:1-2, s. 412-414
-
Tidskriftsartikel (refereegranskat)abstract
- The first stage of the AMANDA High Energy Neutrino Detector at the South Pole, the 302 PMT array AMANDA-B with an expected effective area for TeV neutrinos of ∼ 104 m2, has been taking data since 1997. Progress with calibration, investigation of ice properties, as well as muon and neutrino data analysis are described. The next stage 20-string detector AMANDA-II with ∼800 PMTs will be completed in spring 2000.
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12. |
- Hammar, M., et al.
(författare)
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Topography dependent doping distribution in selectively regrown InP studied by scanning capacitance microscopy
- 1998
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 72:7, s. 815-817
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Tidskriftsartikel (refereegranskat)abstract
- We have used scanning capacitance microscopy (SCM) to study the dopant distribution in regrown InP with high sensitivity and spatial resolution. Sulfur or iron doped InP was selectively regrown around n-doped InP mesas using hydride vapor phase epitaxy, and the resulting structure was imaged in cross section by SCM. For calibration purposes, reference layers with known doping levels were grown directly on top of the region of interest. Dramatic variations in the carrier concentration around the mesa, as well as pronounced differences in the behavior of S and Fe are observed. We correlate these findings to the growth and doping incorporation mechanisms. © 1998 American Institute of Physics.
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14. |
- Mullins, S. M., et al.
(författare)
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Strong population of a superdeformed band in Eu142
- 1995
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Ingår i: Physical Review C. - 0556-2813. ; 52:1, s. 99-103
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Tidskriftsartikel (refereegranskat)abstract
- A superdeformed band has been found in Eu142. It is populated with 1.2(2)% of the total -ray intensity that decayed into Eu142 via the reaction Sn120(27Al,5n)142Eu at 152 MeV. The strength of the band is similar to that previously reported in Eu143, where the superdeformed band is populated with an intensity of 1.1(1)%. This is unexpected, since both total Routhian surface (TRS) and cranked modified oscillator (MO) calculations predict that the superdeformed band in Eu143 becomes yrast at lower spin than that in Eu142. This difference is 4Latin small letter h with stroke in the MO calculations and 8Latin small letter h with stroke in the TRS. Extrapolation of the normal-deformed yrast states in Eu143 shows, however, that a difference of 8Latin small letter h with stroke in spin corresponds to a change in the relative energy of the superdeformed and normal-deformed yrast lines of only 1 MeV.
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15. |
- Rodriguez, M, et al.
(författare)
-
CT in malignancy grading and prognostic prediction of non-Hodgkin's lymphoma
- 1999
-
Ingår i: Acta Radiologica. - 0284-1851 .- 1600-0455. ; 40:2, s. 191-197
-
Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The presence of tumor inhomogeneities in MR images of non-Hodgkin's lymphoma (NHL) provides information about malignancy grade and prognosis. The aim of this study was to determine whether CT images are also informative in these respects. MATERIAL AND METHODS: Sixty-three CT examinations in patients with NHL (32 high-grade and 31 low-grade tumors) were reviewed retrospectively by two senior radiologists. The tumor patterns were classified subjectively as homogeneous, slightly inhomogeneous or severely inhomogeneous and their relations to malignancy grade, clinical characteristics and prognosis were determined. RESULTS: Sixteen out of 17 patients with a severely inhomogeneous tumor pattern had high-grade NHL tumors while 21 out of 29 patients with a homogeneous tumor appearance had low-grade NHL tumors. Among chemotherapy-treated patients, those with the highest degree of inhomogeneity had a significantly worse prognosis (9 out of 11 patients died). This relationship was not found in patients treated with radiotherapy. CONCLUSION: A severely inhomogeneous tumor pattern on CT images was found to be associated with a high malignancy grade in NHL. This CT pattern was also compatible with a poor prognosis in patients treated with chemotherapy.
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16. |
- vanDoorslaer, E, et al.
(författare)
-
Income-related inequalities in health: Some international comparisons
- 1997
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Ingår i: JOURNAL OF HEALTH ECONOMICS. - : ELSEVIER SCIENCE BV. - 0167-6296. ; 16:1, s. 93-112
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents evidence on income-related inequalities in self-assessed health in nine industrialized countries. Health interview survey data were used to construct concentration curves of self-assessed health, measured as a latent variable. Inequali
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22. |
- GARCIA, JR, et al.
(författare)
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A CATALOG OF VARIABLE-STARS IN THE LOWER INSTABILITY STRIP
- 1995
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Ingår i: ASTRONOMY & ASTROPHYSICS SUPPLEMENT SERIES. - 0365-0138. ; 109:2, s. 201-262
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Identifications, positions, photometry, spectra, some pulsational features, other astrophysical parameters and literature for 302 pulsating variable stars in the lower instability strip, near the ZAMS, are given. About 185 stars have near homogeneous phot
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27. |
- Marklund, S, et al.
(författare)
-
Molecular basis for the dominant white phenotype in the domestic pig.
- 1998
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Ingår i: Genome research. - 1088-9051. ; 8:8, s. 826-33
-
Tidskriftsartikel (refereegranskat)abstract
- The change of phenotypic traits in domestic animals and crops as a response to selective breeding mimics the much slower evolutionary change in natural populations. Here, we describe that the dominant white phenotype in domestic pigs is caused by two mutations in the KIT gene encoding the mast/stem cell growth factor receptor (MGF), one gene duplication associated with a partially dominant phenotype and a splice mutation in one of the copies leading to the fully dominant allele. The splice mutation is a G to A substitution in the first nucleotide of intron 17 and leads to skipping of exon 17. The duplication is most likely a regulatory mutation affecting KIT expression, whereas the splice mutation is expected to cause a receptor with impaired or absent tyrosine kinase activity. Immunocytochemistry showed that this variant form is expressed in 17- to 19-day-old pig embryos. Hundreds of millions of white pigs around the world are assumed to be heterozygous or homozygous for the two mutations. [The EMBL accession numbers for porcine KIT1*0101, KIT1*0202, KIT2*0202, and KIT2*0101 are AJ223228-AJ223231, respectively.]
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28. |
- Massaro, Dominic W., et al.
(författare)
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Picture My Voice : Audio to Visual Speech Synthesis using Artificial Neural Networks
- 1999
-
Ingår i: Proceedings of International Conference on Auditory-Visual Speech Processing. ; , s. 133-138
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents an initial implementation and evaluation of a system that synthesizes visualspeech directly from the acoustic waveform. Anartificial neural network (ANN) was trained tomap the cepstral coefficients of an individual’snatural speech to the control parameters of ananimated synthetic talking head. We trained ontwo data sets; one was a set of 400 words spokenin isolation by a single speaker and the other a subset of extemporaneous speech from 10different speakers. The system showed learning inboth cases. A perceptual evaluation test indicatedthat the system’s generalization to new words bythe same speaker provides significant visible information, but significantly below that given bya text-to-speech algorithm.
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38. |
- Ruigomez, A, et al.
(författare)
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Use of cimetidine, omeprazole and ranitidine in pregnant women and pregnancy outcomes
- 1999
-
Ingår i: American Journal of Epidemiology. - 0002-9262 .- 1476-6256. ; 150:5, s. 476-481
-
Tidskriftsartikel (refereegranskat)abstract
- Evidence documenting the safety of acid-suppressing drugs in pregnancy is very limited. The authors assessed the prevalence of congenital malformations in first trimester-exposed pregnancies to cimetidine, omeprazole, and ranitidine and compared it with nonexposed pregnancies between 1991 and 1996. Two different sources were used, the United Kingdom General Practice Research Database and the Italian Friuli-Venezia Giulia Health Database. The final study cohort included 1, 179 pregnancies from the United Kingdom and 1, 057 from Italy. Abortions or ectopic pregnancies were not included. There were 20 stillbirths and 2, 261 live-born babies in both cohorts combined, with 100 offspring identified with a malformation. The overall malformation rate was 4.4%. The relative risks for nongenetic congenital malformations associated with the use of cimetidine, omeprazole, and ranitidine were 1.2 (95% confidence interval (CI): 0.6, 2.3), 0.9 (95% CI: 0.3, 2.2), and 1.4 (95% CI: 0.8, 2.4), respectively, compared with the nonexposed. No specific grouping in the distribution of malformations was observed in any of the three exposed groups. Moreover, no relation was found between drug exposure and preterm delivery or growth retardation. These findings suggest that the use of acid-suppressing drugs during the first trimester of pregnancy is not associated with a major teratogenic risk.
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