| 1. |
- Oellers, D., et al.
(författare)
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Polarizing a stored proton beam by spin flip?
- 2009
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Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 674:4-5, s. 269-275
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Tidskriftsartikel (refereegranskat)abstract
- We discuss polarizing a proton beam in a storage ring, either by selective removal or by spin flip of the stored ions. Prompted by recent, conflicting calculations, we have carried out a measurement of the spin-flip cross section in low-energy electron–proton scattering. The experiment uses the cooling electron beam at COSY as an electron target. The measured cross sections are too small for making spin flip a viable tool in polarizing a stored beam. This invalidates a recent proposal to use co-moving polarized positrons to polarize a stored antiproton beam.
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| 2. |
- Augustyniak, W., et al.
(författare)
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Polarization of a stored beam by spin-filtering
- 2012
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Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 718:1, s. 64-69
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Tidskriftsartikel (refereegranskat)abstract
- The PAX Collaboration has successfully performed a spin-filtering experiment with protons at the COSY-ring. The measurement allowed the determination of the spin-dependent polarizing cross section, that compares well with the theoretical prediction from the nucleon-nucleon potential. The test confirms that spin-filtering can be adopted as a method to polarize a stored beam and that the present interpretation of the mechanism in terms of the proton-proton interaction is correct. The outcome of the experiment is of utmost importance in view of the possible application of the method to polarize a beam of stored antiprotons.
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| 3. |
- Oellers, D., et al.
(författare)
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New experimental upper limit of the electron-proton spin-flip cross-section
- 2014
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 759, s. 6-9
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Tidskriftsartikel (refereegranskat)abstract
- In a previous publication, measurements of the depolarization of a stored proton beam by interaction with a co-propagating unpolarized electron beam at low relative energy have been presented and an upper limit of about 3 x 10(7) b for the electron-proton spin flip cross-section was determined. A refined analysis presented in this paper reduces the previous upper limit by a factor of three by the introduction of a new procedure that, also makes use of non-identified particles.
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| 4. |
- Mielke, Kati, 1981-, et al.
(författare)
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Abundance of metalloprotease FtsH12 modulates chloroplast development in Arabidopsis thaliana
- 2021
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Ingår i: Journal of Experimental Botany. - : Oxford University Press. - 0022-0957 .- 1460-2431. ; 72:9, s. 3455-3473
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Tidskriftsartikel (refereegranskat)abstract
- The ATP-dependent metalloprotease FtsH12 (filamentation temperature sensitive protein H 12) has been suggested to participate in a heteromeric motor complex, driving protein translocation into the chloroplast. FtsH12 was immuno-detected in proplastids, seedlings, leaves, and roots. Expression of Myc-tagged FtsH12 under its native promotor allowed identification of FtsHi1, 2, 4, and 5, and plastidic NAD-malate dehydrogenase, five of the six interaction partners in the suggested import motor complex. Arabidopsis thaliana mutant seedlings with reduced FTSH12 abundance exhibited pale cotyledons and small, deformed chloroplasts with altered thylakoid structure. Mature plants retained these chloroplast defects, resulting in slightly variegated leaves and lower chlorophyll content. Label-free proteomics revealed strong changes in the proteome composition of FTSH12 knock-down seedlings, reflecting impaired plastid development. The composition of the translocon on the inner chloroplast membrane (TIC) protein import complex was altered, with coordinated reduction of the FtsH12-FtsHi complex subunits and accumulation of the 1 MDa TIC complex subunits TIC56, TIC214 and TIC22-III. FTSH12 overexpressor lines showed no obvious phenotype, but still displayed distinct differences in their proteome. N-terminome analyses further demonstrated normal proteolytic maturation of plastid-imported proteins irrespective of FTSH12 abundance. Together, our data suggest that FtsH12 has highest impact during seedling development; its abundance alters the plastid import machinery and impairs chloroplast development.
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| 5. |
- Tavares, W. S., et al.
(författare)
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Parasitism of Palmistichus elaeisis Delvare & LaSalle, 1993 on pupae of Methona themisto (Hubner, [1818]) reared on two hosts (Lepidoptera: Nymphalidae; Hymenoptera: Eulophidae)
- 2013
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Ingår i: Shilap: Revista de Lepidopterologia. - 0300-5267. ; 41:161, s. 43-48
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies showed that larvae of Methona themisto (Hubner, [ 1818]) (Lepidoptera: Nymphalidae) display a showy yellow color to avoid predation. In addition, these larvae absorb secondary compounds when feeding on Brunfelsia uniflora (Pohl) D. Don (Solanaceae) plants, although this does not prevent pupal parasitism by Palmistichus elaeisis Delvare & LaSalle, 1993 (Hymenoptera: Eulophidae). The aim of this study was to assess in the laboratory parasitism by P. elaeisis on pupae of M. themisto after their larvae fed on a new host plant, Inga edulis Martius (Fabaceae) (T1) cultivated in the herbarium of the Federal University of Vicosa (UFV) in Vicosa, Minas Gerais State, Brazil or on plants of B. uniflora (T2) cultivated in the campus of the UFV. The percentage of emergence, developmental time, number of individuals emerged and sex ratio of adults of P. elaeisis and the length and width of the pupae of M. themisto were similar between treatments (P > 0.05). Palmistichus elaeisis showed good reproductive performance when reared on pupae of the host M. themisto independently of larval food.
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