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Träfflista för sökning "WFRF:(Johnson R. E.) ;srt2:(1995-1999)"

Search: WFRF:(Johnson R. E.) > (1995-1999)

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1.
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2.
  • Edelson, R. A., et al. (author)
  • Multiwavelength observations of short-timescale variability in NGC 4151. IV. Analysis of multiwavelength continuum variability
  • 1996
  • In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 470:1, s. 364-377377
  • Journal article (peer-reviewed)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.
  • Crenshaw, D. M., et al. (author)
  • Multiwavelength observations of short-timescale variability in NGC 4151. I. Ultraviolet observations
  • 1996
  • In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 470:1, s. 322-335335
  • Journal article (peer-reviewed)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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4.
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5.
  • Dunham, I, et al. (author)
  • The DNA sequence of human chromosome 22
  • 1999
  • In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 402:6761, s. 489-495
  • Journal article (peer-reviewed)
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6.
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7.
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8.
  • Kownacki, J, et al. (author)
  • High-spin studies of the neutron deficient nuclei In-103, In-105, In-107, and In-109
  • 1997
  • In: Nuclear Physics A. - 0375-9474 .- 1873-1554. ; 627:2, s. 239-258
  • Journal article (peer-reviewed)abstract
    • High-spin states of the isotopes 103,105,107,109In have been investigated using in-beam γ-ray spectroscopic methods. Results from three different experiments are presented. Targets of 54Fe, 50Cr, and 92Mo were bombarded by a 270 and 261 MeV 58Ni beam and by a 95 MeV 19F beam, respectively. Reaction channel separation was achieved with a charged-particle detector array and in the first two experiments also with a 1π neutron detector system. As a result of these experiments the level schemes of 103,105,107,109In were significantly extended. Excited states of these odd-A indium isotopes are discussed within the framework of the nuclear shell model and the hole-core coupling scheme. The systematics of excited states of light odd-A indium isotopes is also discussed.
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9.
  • CEDERKALL, J, et al. (author)
  • 1ST OBSERVATION OF EXCITED-STATES IN SB-108
  • 1995
  • In: Nuclear Physics A. - 0375-9474 .- 1873-1554. ; 581:1, s. 189-204
  • Journal article (peer-reviewed)abstract
    • A spectroscopic study of Sb-108 has been carried out as a part of a larger experiment where in total twenty-nine different residual nuclei were identified. This study gives the first information on excited levels in this nucleus. A low-lying two-quasi-particle multiplet together with some of the higher lying levels are discussed within the framework of the nuclear shell model. A rotational, strongly coupled, band is identified as, most likely, being built on the deformed pig9/2(-1) nuh11/2 configuration in accordance with total routhian surface calculations. Tentative spins and parities are presented as well as B(M1)/B(E2) ratios for some of the transitions in the strongly coupled band.
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10.
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11.
  • De Angelis, G., et al. (author)
  • Collective Excitations in the Vicinity of N=Z
  • 1999. - 1 SUPPL. 1
  • In: Proceedings INPC 1998. - 0375-9474. ; 654, s. 659-662
  • Conference paper (peer-reviewed)abstract
    • In our contribution to the INPC98 conference we reported on the experimental investigation of high spin collective states in medium and heavy mass N≈Z nuclei at LNL. The main purpose is to set light on the role of the proton-neutron interaction in the collective behavior of the nucleus. In medium mass N=Z nuclei, in contrast with the stable nuclei, valence protons and neutrons occupy the same orbitals and one may expect a reinforcement of neutron-proton T=0 (np) pairing correlations[1]. In this interesting subject, the medium mass N=Z=36 72Kr has been studied and completely reported in [2]. In this proceedings we will concentrate in unpublished results concerning the onset of collectivity on nearly spherical nuclei in the 100Sn region. In nuclei with Z=50 and Z=49 dipole bands have been found indicating the presence of "Magnetic Rotation" [3].
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12.
  • DOMBRADI, Z, et al. (author)
  • HIGH-SPIN SPECTROSCOPY OF TE-109
  • 1995
  • In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 51:5, s. 2394-2399
  • Journal article (peer-reviewed)
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13.
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14.
  • Juutinen, S, et al. (author)
  • Coexistence of collective and quasiparticle structures in Sn-106 and Sn-108
  • 1997
  • In: Nuclear Physics A. - 0375-9474 .- 1873-1554. ; 617:1, s. 74-90
  • Journal article (peer-reviewed)abstract
    • New levels in the neutron deficient nuclei Sn-106 and Sn-108 have been investigated by using the NORDBALL detector array combined with charged particle and neutron detectors. The excited structures are discussed in terms of collectivity and the shell model. The excitations are interpreted to be based on d5/2, g7/2 and h(11/2) both for protons and neutrons and g(9/2) for protons. The systematical behaviour of the specific states in the Sn isotopes is studied in the mass range of A = 106-118.
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15.
  • Juutinen, S, et al. (author)
  • Coexistence of collective and quasiparticle structures in Sn-106 and Sn-108
  • 1997
  • In: NUCLEAR PHYSICS A. - : ELSEVIER SCIENCE BV. - 0375-9474. ; 617:1, s. 74-90
  • Journal article (other academic/artistic)abstract
    • New levels in the neutron deficient nuclei Sn-106 and Sn-108 have been investigated by using the NORDBALL detector array combined with charged particle and neutron detectors. The excited structures are discussed in terms of collectivity and the shell mode
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16.
  • KLAMRA, W, et al. (author)
  • HIGH-SPIN BAND STRUCTURES IN CD-104
  • 1995
  • In: Zeitschrift für Physik A Hadrons and Nuclei. - 0939-7922 .- 1431-5831. ; 352:2, s. 117-118
  • Journal article (peer-reviewed)abstract
    • High spin states in Cd-104 have been investigated by means of heavy ion induced reactions using the Nordball detector array. The level scheme constructed from yy-coincidences is dominated by three band structures, The positive parity band shows no rotational like energy spacing, It is thus understood mostly in terms of quasiparticle excitations with vd(5/2), Vg(7/2) and pi g(9/2) configurations, The collective properties of the negative parity bands are more pronounced. These bands are most likely due to v(h(11/2),d(5/2)) and v(h(11/2)g(7/2)) structures.
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17.
  • Kownacki, J, et al. (author)
  • The isospin dependent p-n multiplets in the region of doubly magic Sn-100
  • 1996
  • Conference paper (peer-reviewed)abstract
    • Experimental data on p-n multiplets appearing in the nuclei near double-magic Sn-100 accesible in heavy-ion fusion-evaporation experiments have been analyzed. Proton-rich nuclei in this region have been investigated using the NORDBALL array. A Ni-58 beams at energies of 270 Mev on Fe-54 and 261 MeV on Cr-50 targets were used. Reaction channel separation was achieved with a 4 pi charged particle multi-detector set-up together with a 1 pi neutron detector wall placed in the forward direction. On the basis of gamma gamma-coincidence and angular correlation relations a level schemes of several light Sn, In, Sb, Te and I nuclei were observed for the first time in the present experiment. The observed structure of nuclei are discussed in the framework of the nuclear shell-model. The p-n multiplets in the A similar to 100 region corresponding to the nucleon pairs with mixed configurations has been considered as a playground for the tests of the T = 0 and T = 1 parts of the effective interaction.
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18.
  • MAKELA, E, et al. (author)
  • COEXISTENCE OF COLLECTIVE AND QUASI-PARTICLE STRUCTURES IN SN-106,SN-108 NUCLEI
  • 1995
  • In: Physica scripta. T. - : ROYAL SWEDISH ACAD SCIENCES. - 0281-1847. ; T56, s. 280-283
  • Journal article (peer-reviewed)abstract
    • New revels in two neutron deficient nuclei Sn-106.108 have been found by using the Nordball detector array extended with the arrangements of charged particle and neutron detectors. The excited structures are discussed in terms of collectivity and the shell model. The systematical behaviour of the states in Sn isotopes is studied in the mass range of A = 104-118.
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19.
  • Perries, S, et al. (author)
  • Decay-out of the yrast superdeformed band in Nd-136 : Towards an experimental extraction of the neutron pairing gap at large deformation
  • 1999
  • In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 60:6
  • Journal article (peer-reviewed)abstract
    • A study of the Nd-136 nucleus has been performed with the EUROBALL III multidetector to establish the decay-out of the yrast superdeformed (SD) band. Three discrete linking transitions (754, 1456, and 1493 keV) have been discovered, establishing the position of the SD band at 7.03 MeV excitation energy with proposed spin and parity 17((-)) for the lowest observed SD state. Neutron pairing gap parameters for SD shapes have been extracted in Nd isotopes, using the strong-coupling model and odd-even mass difference formulas. The major conclusion of our phenomenological analysis is that the pairing correlations do subsist in the SD configurations of nuclei in the A = 130 mass region. [S0556-2813(99)01312-6].
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20.
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21.
  • SEWERYNIAK, D, et al. (author)
  • IN-BEAM STUDY OF IN-102, IN-104 AND IN-106
  • 1995
  • In: Nuclear Physics A. - 0375-9474 .- 1873-1554. ; 589:1, s. 175-200
  • Journal article (peer-reviewed)abstract
    • Proton-rich odd-odd In isotopes have been investigated by in-beam spectroscopic methods using the NORDBALL detector array. A Ni-58 beam with an energy of 270 MeV was used to bombard a Fe-54 target. Separation of different reaction channels was achieved with a 4 pi charged-particle multi-detector set-up together with a 1 pi neutron detector wall placed in the forward direction. Excited states of the In-102 nucleus were identified for the first time as well as a set of negative-parity states in In-104. In In-106 the information about positive- and negative-parity states has been extended. The nuclei are discussed within the framework of the nuclear shell model, the interacting boson-fermion-fermion model and the systematics of the heavier odd-odd indium isotopes.
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22.
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23.
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24.
  • de, Angelis G, et al. (author)
  • Rotation induced octupole correlations in the neutron-deficient Te-109 nucleus
  • 1998
  • In: Physics Letters B. - 0370-2693 .- 1873-2445. ; 437:3-4, s. 236-242
  • Journal article (peer-reviewed)abstract
    • High spin states in the neutron deficient nucleus 109Te have been populated with the 58Ni+54Fe reaction at 220 MeV and investigated through γ-spectroscopy methods at the GASP spectrometer making use of reaction channel selection with the ISIS Si-ball. The level scheme has been extended up to an excitation energy of ≈12.1 MeV. The spins and parities of the observed levels are assigned tentatively supporting the identification of two bands of opposite parity connected by strong dipole transitions inferred to be of E1 character. Octupole correlations in 109Te induced by rotation are suggested as the cause of this effect.
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25.
  • KLAMRA, W, et al. (author)
  • HIGH-SPIN BAND STRUCTURES IN CD-104
  • 1995
  • In: ZEITSCHRIFT FUR PHYSIK A-HADRONS AND NUCLEI. - : SPRINGER VERLAG. - 0939-7922. ; 352:2, s. 117-118
  • Journal article (peer-reviewed)abstract
    • High spin states in Cd-104 have been investigated by means of heavy ion induced reactions using the Nordball detector array. The level scheme constructed from yy-coincidences is dominated by three band structures, The positive parity band shows no rotatio
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26.
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27.
  • Palacz, M, et al. (author)
  • In-beam gamma-ray spectroscopy of Co-56
  • 1997
  • In: NUCLEAR PHYSICS A. - : ELSEVIER SCIENCE BV. - 0375-9474 .- 1873-1554. ; 627:1, s. 162-174
  • Journal article (other academic/artistic)abstract
    • Excited states of Co-56 were studied in the reaction Al-27(S-32,2p1n) Co-56. The NORDBALL array with a Neutron Wall and a Silicon Ball was employed. The excited states were interpreted in terms of particle-hole excitations with respect to the doubly magic
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28.
  • Palacz, M, et al. (author)
  • In beam gamma-ray spectroscopy of very neutron deficient odd-cadmium isotopes
  • 1997
  • In: Acta Physica Polonica B. - : ACTA PHYSICA POLONICA B, JAGELLONIAN UNIV, INST PHYSICS. - 0587-4254 .- 1509-5770. ; 28:1-2, s. 309-313
  • Journal article (peer-reviewed)abstract
    • Excited states in the very neutron deficient odd cadmium isotopes Cd-99, Cd-101 and Cd-103 are discussed in terms of the nuclear shell model. Systematics of excited states in Cd99-109 is presented.
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29.
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30.
  • Wagstaff, A, et al. (author)
  • Equity in the finance of health care: some further international comparisons
  • 1999
  • In: JOURNAL OF HEALTH ECONOMICS. - : ELSEVIER SCIENCE BV. ; 18:3
  • Other publication (other academic/artistic)abstract
    • This paper presents further international comparisons of progressivity of health care financing systems. The paper builds on the work of Wagstaff et al, [Wagstaff, A., van Doorslaer E,, et al., 1992. Equity in the finance of health care: some internation
  •  
31.
  • Cederkall, J, et al. (author)
  • First evidence for excited states in In-101
  • 1996
  • In: PHYSICAL REVIEW C-NUCLEAR PHYSICS. - : AMER INST PHYSICS. - 0556-2813. ; 53:4, s. 1955-1958
  • Journal article (other academic/artistic)abstract
    • The first evidence for excited states in In-101 is presented. In-101 is the lightest In isotope observed in an in-beam experiment. Two gamma-ray transitions at 1309 and 341 keV, respectively, are strong candidates for a cascade to the ground state in this
  •  
32.
  • Horger, B A, et al. (author)
  • Neurturin exerts potent actions on survival and function of midbrain dopaminergic neurons
  • 1998
  • In: The Journal of Neuroscience. - 1529-2401. ; 18:13, s. 4929-4937
  • Journal article (peer-reviewed)abstract
    • Glial cell line-derived neurotrophic factor (GDNF) exhibits potent effects on survival and function of midbrain dopaminergic (DA) neurons in a variety of models. Although other growth factors expressed in the vicinity of developing DA neurons have been reported to support survival of DA neurons in vitro, to date none of these factors duplicate the potent and selective actions of GDNF in vivo. We report here that neurturin (NTN), a homolog of GDNF, is expressed in the nigrostriatal system, and that NTN exerts potent effects on survival and function of midbrain DA neurons. Our findings indicate that NTN mRNA is sequentially expressed in the ventral midbrain and striatum during development and that NTN exhibits survival-promoting actions on both developing and mature DA neurons. In vitro, NTN supports survival of embryonic DA neurons, and in vivo, direct injection of NTN into the substantia nigra protects mature DA neurons from cell death induced by 6-OHDA. Furthermore, administration of NTN into the striatum of intact adult animals induces behavioral and biochemical changes associated with functional upregulation of nigral DA neurons. The similarity in potency and efficacy of NTN and GDNF on DA neurons in several paradigms stands in contrast to the differential distribution of the receptor components GDNF Family Receptor alpha1 (GFRalpha1) and GFRalpha2 within the ventral mesencephalon. These results suggest that NTN is an endogenous trophic factor for midbrain DA neurons and point to the possibility that GDNF and NTN may exert redundant trophic influences on nigral DA neurons acting via a receptor complex that includes GFRalpha1.
  •  
33.
  • Kownacki, J, et al. (author)
  • The isospin dependent p-n multiplets in the region of doubly magic Sn-100
  • 1996
  • In: ACTA PHYSICA POLONICA B. - : POLISH ACAD SCIENCES INST PHYSICS. ; 27:1-2, s. 87-97
  • Journal article (other academic/artistic)abstract
    • Experimental data on p-n multiplets appearing in the nuclei near double-magic Sn-100 accesible in heavy-ion fusion-evaporation experiments have been analyzed. Proton-rich nuclei in this region have been investigated using the NORDBALL array. A Ni-58 beams
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34.
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35.
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36.
  • Persson, J, et al. (author)
  • In-beam gamma-ray spectroscopy of Cd-102
  • 1997
  • In: Nuclear Physics A. - : ELSEVIER SCIENCE BV. - 0375-9474 .- 1873-1554. ; 627:1, s. 101-118
  • Journal article (peer-reviewed)abstract
    • Neutron deficient nuclei close to 100Sn have been studied using the NORDBALL Ge-detector array together with ancillary particle detectors. Evaporation residues from the compound nucleus 108Te were identified with charged particle and neutron detectors. In this paper a considerable extension of the level scheme of the nucleus 102Cd is presented. The strongest cascade of the new level scheme reveals an irregular sequence of dipole transitions above Iπ = 10+ extending up to spin 17. A strongly populated rather regular side band consisting of four quadrupole transitions ranging from spin 9 to spin 17 was also discovered. This band was tentatively assigned negative parity. Shell model calculations were performed and a very good agreement with the experimental results was found. The excited states could successfully be interpreted as neutron particle and proton hole excitations with respect to the doubly closed core 50100Sn50.
  •  
37.
  • Persson, J, et al. (author)
  • New spectroscopic data on Cd-102
  • 1996
  • In: Acta Physica Polonica B. - : POLISH ACAD SCIENCES INST PHYSICS. - 0587-4254 .- 1509-5770. ; 27:1-2, s. 171-178
  • Journal article (peer-reviewed)abstract
    • Gamma ray spectroscopy of neutron deficient nuclei close to the doubly magic nucleus Sn-100 has been performed using a heavy-ion reaction and the NORDBALL Ge-detector array. Evaporation residues were identified by means of charged particle and neutron detection. Transitions in 31 different evaporation residues were identified. New results on Cd-102 are presented.
  •  
38.
  • Sohler, D, et al. (author)
  • Spectroscopy of neutron deficient Ge-65
  • 1997
  • In: Zeitschrift für Physik A Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 0939-7922 .- 1431-5831. ; 357:3, s. 239-240
  • Journal article (peer-reviewed)abstract
    • Excited states of 65Ge were populated via the 12C + 58Ni (261 MeV) reaction using the NORDBALL detector array equipped with charged-particle and neutron detector systems for reaction channel separation. On the basis of γγ-coincidence relations and angular distribution ratios a significantly extended level scheme was constructed up to E x = 9 MeV and J π = (33/2−). The low-energy states of the nucleus are discussed in the framework of the interacting boson-fermion model.
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39.
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