| 1. |
- Li, Wenxian, et al.
(författare)
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A Novel Method to Determine Magnetic Fields in Low-density Plasma Facilitated Through Accidental Degeneracy of Quantum States in Fe9
- 2015
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Ingår i: Astrophysical Journal. - 0004-637X. ; 807:1
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Tidskriftsartikel (refereegranskat)abstract
- We propose a new method to determine magnetic fields, by using the magnetic-field-induced electric dipole transition 3p(4) 3d D-4(7/2) -> 3p(5) P-3/2 in Fe9+ ions. This ion has a high abundance in astrophysical plasma and is therefore well suited for direct measurements of even rather weak fields in, e.g., solar flares. This transition is induced by an external magnetic field and its rate is proportional to the square of the magnetic field strength. We present theoretical values for what we will label the reduced rate and propose that the critical energy difference between the upper level in this transition and the close-to-degenerate 3p(4) 3d D-4(5/2) should be measured experimentally since it is required to determine the relative intensity of this magnetic line for different magnetic fields.
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| 2. |
- Li, Wenxian, et al.
(författare)
-
ATOMIC-LEVEL PSEUDO-DEGENERACY of ATOMIC LEVELS GIVING TRANSITIONS INDUCED by MAGNETIC FIELDS, of IMPORTANCE for DETERMINING the FIELD STRENGTHS in the SOLAR CORONA
- 2016
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Ingår i: Astrophysical Journal. - 0004-637X. ; 826:2
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Tidskriftsartikel (refereegranskat)abstract
- We present a measured value for the degree of pseudo-degeneracy between two fine-structure levels in Fe9+ from line intensity ratios involving a transition induced by an external magnetic field. The extracted fine-structure energy difference between 3p4 3d 4D7/2 the and 4D7/2 levels, where the latter is the upper state for the magnetic-field induced line, is needed in our recently proposed method to measure magnetic-field strengths in the solar corona. The intensity of the 3p4 3d 4D7/2 → 3p5 2 P3/2 line at 257.262 Å is sensitive to the magnetic field external to the ion. This sensitivity is in turn strongly dependent on the energy separation in the pseudo-degeneracy through the mixing induced by the external magnetic field. Our measurement, which uses an Electron Beam Ion Trap with a known magnetic-field strength, indicates that this energy difference is 3.5 cm-1. The high abundance of Fe9+ and the sensitivity of the line's transition probability to field strengths below 0.1 T opens up the possibility of diagnosing coronal magnetic fields. We propose a new method to measure the magnetic field in the solar corona, from similar intensity ratios in Fe9+. In addition, the proposed method to use the line ratio of the blended line 3p4 3d 4D7/2.5/2 → 3p5 2P3/2 with another line from Fe x as the density diagnostic should evaluate the effect of the magnetic-field-induced transition line.
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| 3. |
- Nakajima, Yoko, et al.
(författare)
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Dihydropyrimidinase deficiency in four East Asian patients due to novel and rare DPYS mutations affecting protein structural integrity and catalytic activity
- 2017
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Ingår i: Molecular Genetics and Metabolism. - : Elsevier BV. - 1096-7192 .- 1096-7206. ; 122:4, s. 216-222
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Tidskriftsartikel (refereegranskat)abstract
- Dihydropyrimidinase (DHP) is the second enzyme of the pyrimidine degradation pathway and catalyzes the ring opening of 5,6-dihydrouracil and 5,6-dihydrothymine. To date, only 31 genetically confirmed patients with a DHP deficiency have been reported and the clinical, biochemical and genetic spectrum of DHP deficient patients is, therefore, still largely unknown. Here, we show that 4 newly identified DHP deficient patients presented with strongly elevated levels of 5,6-dihydrouracil and 5,6-dihydrothymine in urine and a highly variable clinical presentation, ranging from asymptomatic to infantile spasm and reduced white matter and brain atrophy. Analysis of the DHP gene (DPYS) showed the presence of 8 variants including 4 novel/rare missense variants and one novel deletion. Functional analysis of recombinantly expressed DHP mutants carrying the p.M250I, p.H295R, p.Q334R, p.T418I and the p.R490H variant showed residual DHP activities of 2.0%, 9.8%, 9.7%, 64% and 0.3%, respectively. The crystal structure of human DHP indicated that all point mutations were likely to cause rearrangements of loops shaping the active site, primarily affecting substrate binding and stability of the enzyme. The observation that the identified mutations were more prevalent in East Asians and the Japanese population indicates that DHP deficiency may be more common than anticipated in these ethnic groups.
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| 4. |
- Wenxian, Li, et al.
(författare)
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A Novel Method to Determine Magnetic Fields in low-density Plasma eg Solar Flares Facilitated Through Accidental Degeneracy of Quantum States in Fe 9
- 2015
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Ingår i: Astrophysical Journal. - : Bibliopolis, Edizioni di Filosofia e Scienze. - 0004-637X .- 1538-4357. ; 807:1
-
Tidskriftsartikel (refereegranskat)abstract
- We propose a new method to determine magnetic fields, by using the magnetic-field-induced electric dipole transition 3p4 3d 4D 7 2 3p P 5 2 3 2 in Fe9+ ions. This ion has a high abundance in astrophysical plasma and is therefore well suited for direct measurements of even rather weak fields in, e.g., solar flares. This transition is induced by an external magnetic field and its rate is proportional to the square of the magnetic field strength. We present theoretical values for what we will label the reduced rate and propose that the critical energy difference between the upper level in this transition and the close-to-degenerate 3p4 3d 4D 5 2 should be measured experimentally since it is required to determine the relative intensity of this magnetic line for different magnetic fields.
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| 5. |
- Yui, Shiro, et al.
(författare)
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YAP/TAZ-Dependent Reprogramming of Colonic Epithelium Links ECM Remodeling to Tissue Regeneration
- 2018
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Ingår i: Cell Stem Cell. - : Elsevier BV. - 1934-5909. ; 22:1, s. 7-49
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Tidskriftsartikel (refereegranskat)abstract
- Tissue regeneration requires dynamic cellular adaptation to the wound environment. It is currently unclear how this is orchestrated at the cellular level and how cell fate is affected by severe tissue damage. Here we dissect cell fate transitions during colonic regeneration in a mouse dextran sulfate sodium (DSS) colitis model, and we demonstrate that the epithelium is transiently reprogrammed into a primitive state. This is characterized by de novo expression of fetal markers as well as suppression of markers for adult stem and differentiated cells. The fate change is orchestrated by remodeling the extracellular matrix (ECM), increased FAK/Src signaling, and ultimately YAP/TAZ activation. In a defined cell culture system recapitulating the extracellular matrix remodeling observed in vivo, we show that a collagen 3D matrix supplemented with Wnt ligands is sufficient to sustain endogenous YAP/TAZ and induce conversion of cell fate. This provides a simple model for tissue regeneration, implicating cellular reprogramming as an essential element.
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