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- Alcorn, J, et al.
(författare)
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Basic instrumentation for Hall A at Jefferson Lab
- 2004
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier BV. - 0167-5087 .- 0168-9002. ; 522:3, s. 294-346
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Tidskriftsartikel (refereegranskat)abstract
- The instrumentation in Hall A at the Thomas Jefferson National Accelerator Facility was designed to study electro-and photo-induced reactions at very high luminosity and good momentum and angular resolution for at least one of the reaction products. The central components of Hall A are two identical high resolution spectrometers, which allow the vertical drift chambers in the focal plane to provide a momentum resolution of better than 2 x 10(-4). A variety of Cherenkov counters, scintillators and lead-glass calorimeters provide excellent particle identification. The facility has been operated successfully at a luminosity well in excess of 10(38) CM-2 s(-1). The research program is aimed at a variety of subjects, including nucleon structure functions, nucleon form factors and properties of the nuclear medium. (C) 2003 Elsevier B.V. All rights reserved.
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| 3. |
- Wang, C. K., et al.
(författare)
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Solvent effects on the electronic structure of a newly synthesized two-photon polymerization initiator
- 2003
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 119:2, s. 1208-1213
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Tidskriftsartikel (refereegranskat)abstract
- Time-dependent hybrid density functional theory in combination with polarized continuum model has been applied to study the solvent effects on the geometrical and electronic structures, as well as one- and two-photon absorption processes, of a newly synthesized asymmetrical charge-transfer (CT) two-photon absorption (TPA) organic molecule. The TPA cross section calculated from a generalized two-state model and solvatochromic shift of the CT state are found to be solvent dependent, for which a nonmonotonic behavior with respect to the polarity of the solvents has been observed. The calculated properties are in good agreement with the experimental data available. The character of the CT state is visualized by plotting its charge density difference from ground state, in which an excess of electron density on the donor side of the molecule is found. This implies that the excited molecule is ready to donate its electron to the surroundings. The energetic aspect of the electron donation is discussed by examining the solvent dependence of the molecular ground state oxidation potential. The importance of the electron correlation for describing the two-photon absorption is also demonstrated.
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| 7. |
- Hedera, P., et al.
(författare)
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Spastic paraplegia, ataxia, mental retardation (SPAR) : A novel genetic disorder
- 2002
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Ingår i: Neurology. - : American Academy of Neurology. - 0028-3878 .- 1526-632X. ; 58:3, s. 411-416
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To describe a kindred with a dominantly inherited neurologic disorder manifested either as uncomplicated spastic paraplegia or ataxia, spastic paraplegia, and mental retardation.Methods: Neurologic examinations and molecular genetic analysis (exclusion of known SCA and HSP genes and loci; and trinucleotide repeat expansion detection [RED]) were performed in six affected and four unaffected subjects in this family. MRI, electromyography (EMG), and nerve conduction studies were performed in three affected subjects.Results: The phenotype of this dominantly inherited syndrome varied in succeeding generations. Pure spastic paraplegia was present in the earliest generation; subsequent generations had ataxia and mental retardation. MRI showed marked atrophy of the spinal cord in all patients and cerebellar atrophy in those with ataxia. Laboratory analysis showed that the disorder was not caused by mutations in genes that cause SCA-1, SCA-2, SCA-3, SCA-6, SCA-7, SCA-8, and SCA-12; not linked to other known loci for autosomal dominant ataxia (SCA-4, SCA-5, SCA-10, SCA-11, SCA-13, SCA-14, and SCA-16); and not linked to known loci for autosomal dominant hereditary spastic paraplegia (HSP) (SPG-3, SPG-4, SPG-6, SPG-8, SPG-9, SPG-10, SPG-12, and SPG-13) or autosomal recessive HSP SPG-7. Analysis of intergenerational differences in age at onset of symptoms suggests genetic anticipation. Using RED, the authors did not detect expanded CAG, CCT, TGG, or CGT repeats that segregate with the disease.Conclusions: The authors describe an unusual, dominantly inherited neurologic disorder in which the phenotype (pure spastic paraplegia or spastic ataxia with variable mental retardation) differed in subsequent generations. The molecular explanation for apparent genetic anticipation does not appear to involve trinucleotide repeat expansion.The spinocerebellar ataxias (SCA) and hereditary spastic paraplegias (HSP), although clinically heterogeneous, typically are discerned as distinct syndromes: insidiously progressive ataxia of SCA typically is distinct from the insidiously progressive spastic gait disturbance of HSP.1-5⇓⇓⇓⇓ We identified a kindred with a unique, dominantly inherited neurologic disorder with features of both HSP and spastic ataxia. The most remarkable feature was the observation that different individuals exhibited different phenotypes within this family. Whereas affected members of the oldest generations exhibited pure spastic paraplegia, affected members in the younger generations exhibited cerebellar ataxia, lower extremity spasticity, and variable mental retardation and subtle dystonia. We designate this novel Spastic Paraplegia, Ataxia, mental Retardation syndrome as SPAR. In this report, we describe the clinical features of this SPAR index family and present our findings supporting that SPAR is genetically distinct from known forms of autosomal dominant HSP and SCA and is not caused by an expanded trinucleotide repeat.
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| 8. |
- Sun, X, et al.
(författare)
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Conspicuous accumulation of transcription elongation repressor hrp130/CA150 on the intron-rich Balbiani ring 3 gene
- 2004
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Ingår i: Chromosoma. - : Springer Science and Business Media LLC. - 0009-5915 .- 1432-0886. ; 113:5, s. 244-257
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Tidskriftsartikel (refereegranskat)abstract
- Chromosomal puffs on the polytene chromosomes in the dipteran Chironomus tentans offer the possibility of comparing the appearance of RNA-binding proteins at different transcription sites. We raised a monoclonal antibody that recognized a 130 kDa protein, designated hrp130. Immunocytological analysis of isolated chromosomes showed that hrp130 is heavily accumulated in a specific puff, called Balbiani ring 3; only occasionally is hrp130 abundant in one or two additional puffs on other chromosomes. The immunolabeling was sensitive to RNase treatment, suggesting that hrp130 is associated with nascent ribonucleoproteins. As shown by immunoelectron microscopy hrp130 is distributed along the active BR3 genes. The full sequence of hrp130 was determined by cDNA cloning. The protein comprises 1028 amino acids and contains three WW domains in the N-terminal half and six FF domains in the C-terminal half of the molecule. The protein is conserved from Caenorhabditis elegans to mammals; the human homolog is known as the transcription elongation repressor CA150. We propose that the abundance of hrp130/CA150 in BR3 is connected with the exceptionally high level of splicing in this locus and that hrp130/CA150 adjusts the transcription rate to the numerous splicing events taking place along the gene to ensure proper splicing.
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| 9. |
- Torkar, K., Riedler, W., Escoubet, C.P., Fehringer, M., Schmidt, R., Grard, R.J., Arends, H., Rudenauer, F., Steiger, W., Narheim, B.T., Svenes, K., Torbert, R., Andre, M., Fazakerley, A., Goldstein, R., Olsen, R.C., Pedersen, A., Whipple, E. and Zhao, H.
(författare)
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Active spacecraft potential control for Cluster - implementation and first results
- 2001
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Ingår i: Annales Geophysicae. ; 9:10-12, s. 1289-1302
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Tidskriftsartikel (refereegranskat)abstract
- Electrostatic charging of a spacecraft modifies the distribution of electrons and ions before the particles enter the sensors mounted on the spacecraft body. The floating potential of magnetospheric satellites in sunlight very often reaches several tens o
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