<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">Ca</mml:mi></mml:mrow><mml:mprescripts /><mml:mrow /><mml:mrow><mml:mn>48</mml:mn></mml:mrow><mml:mrow /><mml:mrow /></mml:mmultiscripts></mml:mrow></mml:math>(<i>d</i>,<i>n</i><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mo>)</mml:mo></mml:mrow><mml:mrow><mml:mn>49</mml:mn></mml:mrow></mml:msup></mml:mr

Jw, Watson; Pairsuwan, W.; Bd, Anderson; Ar, Baldwin; Bs, Flanders; Lebo, C.; Madey, R.; Jd, Brown; Foster, C.; Friesel, D.; Nann, H.; Stephenson, E.J.; Pb, Foot; Shute, G.G.; Bm, Spicer

doi:10.1103/physrevc.40.570

Cited by 11 publications

(8 citation statements)

References 18 publications

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“…This is consistent with global OM fits [26,27] which have a significant asymmetry dependence for W s (E), but none for W v (E). Theoretically some asymmetry dependence of W v (E) would be expected and [22,23,24,28,29,30,31] to DOM calculations. For the levels indicated with the solid dots, their energies were included in the fits.…”

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confidence: 99%

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Asymmetry Dependence of Proton Correlations

2006

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A dispersive optical model analysis of p+ 40 Ca and p+ 48 Ca interactions has been carried out. The real and imaginary potentials have been constrained from fits to elastic scattering data, reaction cross sections, and level properties of valence hole states deduced from (e, e ′ p) data. The surface imaginary potential was found to be larger overall and the gap in this potential on either side of the Fermi energy was found to be smaller for the neutron-rich p+ 48 Ca system. These results imply that protons with energies near the Fermi surface experience larger correlations with increasing asymmetry.PACS numbers: 21.10. Pc,24.10.Ht,11.55.Fv In the independent-particle model, nucleons in the nucleus move in a mean-field potential generated by the other nucleons. All nucleon levels up until the Fermi energy (E F ) are fully occupied, while those above are empty. Although this model enables an understanding of various aspects of nuclear structure, a full description of nuclei and nuclear matter requires consideration of the correlations between the nucleons. These include short-range, central and tensor interactions and longer range correlations associated with low-lying collective excitations [2]. As a result, for closed-shell nuclei, singleparticle (sp) levels below E F have an occupancy of only 70-80% and the levels at higher energy have a nonzero occupancy [3]. The strength of the sp levels are spread over energy, with narrow peaks or broad distributions (depending on their separation from E F ). In addition, there is strength at very high momentum [4].Although there are numerous studies of the effect of correlations on the properties of sp levels for nuclei near stability, there are only a few studies for very neutron or proton-rich nuclei. From neutron knock-out reactions, Gade et al. [5] infer the occupancy of the 0d 5/2 neutron hole state in the proton-rich 32 Ar nucleus is considerably reduced relative to those for stable nuclei.An alternate method to study sp strength is through the use of the dispersive optical model (DOM) developed by Mahaux and Sartor [6]. This description employs the Kramers-Kronig dispersion relation that links the imaginary and real parts of the nucleon self-energy [7]. This procedure links optical-model (OM) analyses of reaction data at positive energies to structural information at negative energies. In the present work, the properties of proton levels in Ca nuclei as a function of asymmetry δ= N −Z A are investigated with the DOM. Previously measured elastic-scattering and reaction-cross-section data for protons on 40 Ca and 48 Ca as well as level properties of hole states in these nuclei, inferred from (e, e ′ p) reactions, were simultaneously fit. The dependence on δ is extracted and used to predict level properties of 60 Ca.In the DOM, the complex energy-dependent potential felt by the protons is comprised of a real V, volume W v and surface W s imaginary components, plus spin-orbit V so and Coulomb V c potentials,are used. The real part of the nuclear potential is assumed...

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“…FIG.4:(Color online) Comparison of experimental proton single-particle levels[22,23,24,28,29,30,31] to DOM calculations. For the levels indicated with the solid dots, their energies were included in the fits.…”

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confidence: 99%

Asymmetry Dependence of Proton Correlations

2006

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“…A considerable number of proteins are released from chromatin by extraction with 0.35 M NaCl among them being ubiquitin which was originally labelled HMG-20 [17]. The sequence of trout testis ubiquitin [18] has been shown to be identical to that of calf thymus ubiquitin [19] and to consist of 74 residues. Of these, 11 are acidic and 11 basic and this high proportion of charged residues represents a similarity to the other HMG proteins.…”

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“…Ubiquitin clearly exists as a free protein in chromatin, and in the case of trout testis it has been shown to be rapidly released (together with HMG-T) on micrococcal nuclease digestion but not on DNase I [21]. This has led to the suggestion [18] that ubiquitin may be located on linker DNA between core particles in transcriptionally active chromatin. Ubiquitin is however also found as a constituent of the conjugate protein A24, in which it is linked via a Gly-Gly peptide at its C-terminal end to the amino group of lysine-119 in histone H2A [22,23].…”

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Structural Studies on Two High‐Mobility‐Group Proteins from Calf Thymus, HMG‐14 and HMG‐20 (Ubiquitin), and Their Interaction with DNA

Cary

King

Crane‐Robinson

et al. 1980

European Journal of Biochemistry

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High mobility group (HMG) protein 14, which, like HMG-17, has been implicated in the structure of 'active chromatin' is shown by 270-MHz NMR and by circular dichroism to be in a disordered conformation in free solution. At low ionic strength protein HMG-14 binds to DNA by weak attachment of the N-terminal half of the molecule and is released by 0.3 M NaCI, the ionic strength at which the protein is extracted from chromatin. The protein HMG-20 (ubiquitin), a constituent of the conjugate protein A24, is shown to be a highly stable compact globular protein that remains folded over a pH range of 1-13 and has a half-denaturation temperature of 85 "C when thermally denatured. Circular dichroism indicates 28% helix and 12% fi sheet. Despite having 15% basic residues it binds only very weakly to DNA. A detailed study of the folding of ubiquitin has been made by a combination of several NMR approaches, including decoupling, nuclear Overhauser enhancement and titration. Several line assignments have been made and it is shown that, although the tyrosine and histidine are buried residues, they are not adjacent to one another nor are they close to either of the phenylalanines, of which at least one is also a buried residue.The chromatin of calf thymus and other mammalian cell types contains a number of non-histone proteins that posses a high proportion of both acidic and basic amino acids. They are removed from chromatin by washing in 0.35 M NaCl and have been termed 'high mobility group' (HMG) proteins [l, 21. HMG-1 and HMG-2 are closely related proteins of molecular weights about 26000 that contain about 20% basic residues and 27% acidic residues, the majority of which are not amidated. Structural studies [3,4] indicate that HMG-1 and HMG-2 possess a high content of secondary structure and considerable tertiary structure, though it is not certain whether the structured domain extends over the whole molecule. HMG-14 and HMG-17 on the other hand are of much lower molecular weight, show considerable sequence homology and consist of 100 and 89 residues respectively. In contrast to HMG-1 and HMG-2, they contain only a very low proportion of hydrophobic amino acids and structural studies of have shown that it does not fold in solution but remains as a disordered chain ~~ Abbreviations.

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21-Scandium

Sukhoruchkin

Soroko

Tables of Excitations From Reactions With Charged Particles. Part 1: Z = 3 - 36

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Ca48(d,n)49

Cited by 11 publications

References 18 publications

Asymmetry Dependence of Proton Correlations

Asymmetry Dependence of Proton Correlations

Structural Studies on Two High‐Mobility‐Group Proteins from Calf Thymus, HMG‐14 and HMG‐20 (Ubiquitin), and Their Interaction with DNA

21-Scandium

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