| 1. |
- Campbell, PJ, et al.
(författare)
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Pan-cancer analysis of whole genomes
- 2020
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 578:7793, s. 82-
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Tidskriftsartikel (refereegranskat)abstract
- Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale1–3. Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4–5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter4; identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation5,6; analyses timings and patterns of tumour evolution7; describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity8,9; and evaluates a range of more-specialized features of cancer genomes8,10–18.
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| 2. |
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| 3. |
- Ovsyannikov, Gennady, 1948, et al.
(författare)
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Proximity effect and electron transport in oxide hybrid heterostructures with superconducting/magnetic interfaces
- 2011
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Ingår i: Superconductor Science and Technology. - : IOP Publishing. - 0953-2048 .- 1361-6668. ; 24:5, s. Art. no. 055012-
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Tidskriftsartikel (refereegranskat)abstract
- We report on electron transport in oxide heterostructures with superconducting/magnetic (S/M) thin film interfaces. The investigated hybrid mesa-heterostructures consist of a cuprate superconductor, a nonsuperconducting cuprate (antiferromagnetic) or manganite (ferromagnetic) interlayer with thickness d(M) = 5-50 nm and a conventional superconductor (Nb). The superconducting critical current (I-C) with a critical current density j(c) = 10(3) A cm(-2) (for d(M) = 10 nm) and a characteristic voltage ICRN = 100-200 mu V (RN is normal resistance) are observed at liquid helium temperature for a CaXSr1-XCuO2 antiferromagnetic cuprate interlayer with a thickness of d(M) = 10-50 nm. The superconducting current-phase relation of heterostructures deviates from the regular sine type, demonstrating a second harmonic component. These hybrid heterostructures with S/M interfaces show unusually high sensitivity to external magnetic fields. When substituting the cuprate interlayer by a manganite film, no critical current was observed although the manganite interlayer was made several times thinner (down to d(M)
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| 4. |
- Demidov, V. V., et al.
(författare)
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Magnetic anisotropy in strained manganite films and bicrystal junctions
- 2013
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 113:16
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Tidskriftsartikel (refereegranskat)abstract
- Transport and magnetic properties of La0.67Sr0.33MnO3 (LSMO) manganite thin films and bicrystal junctions were investigated. Epitaxial manganite films were grown on SrTiO3, LaAlO3, NdGaO3 (NGO), and (LaAlO3)(0.3) + (Sr2AlTaO6)(0.7) substrates, and their magnetic anisotropy were determined by two independent techniques of magnetic resonance spectroscopy. It was demonstrated that by using these techniques, a small (0.3%) anisotropy of crystal structure at the (110) surface plane of the orthorhombic NGO substrate leads to uniaxial magnetic anisotropy of the films in the plane of the substrate at least at the room temperature. It was found that on vicinal NGO substrates, the value of magnetic anisotropy strength can be varied in the range 100-200 Oe at T = 295 K by changing the substrate vicinal angle from 0 degrees to 25 degrees. Measurement of the magnetic anisotropy of manganite bicrystal junction demonstrated the presence of two ferromagnetic spin subsystems for both types of bicrystal boundaries with tilting of basal plane of manganite tilted bicrystal (TB-junction) and with rotation of crystallographic axes (RB-junction) used for comparison. The magnetoresistance of TB-junctions increases with decreasing temperature and the misorientation angle. Variation of bicrystal misorientation angle does not lead to change of misorientation of easy magnetic axes in the film parts forming TB-junction. Analysis of the voltage dependencies of bicrystal junction conductivity show that the low value of the magnetoresistance for the LSMO bicrystal junctions can be caused by two scattering mechanisms. The first one is the spin-flip of spin-polarized carriers due to the strong electron-electron interactions in a disordered layer at the bicrystal boundary at low temperatures and the second one is spin-flip by antiferromagnetic magnons at high temperatures.
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| 5. |
- Petrzhik, A. M., et al.
(författare)
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Electron transport in hybrid superconductor heterostructures with manganite interlayers
- 2011
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Ingår i: Journal of Experimental and Theoretical Physics. - : Pleiades Publishing Ltd. - 1090-6509 .- 1063-7761. ; 112:6, s. 1042-1050
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Tidskriftsartikel (refereegranskat)abstract
- Hybrid herostructures comprising an YBa(2)Cu(3)O (x) (YBCO) high-temperature superconductor (HTS) layer and Nb/Au low-temperature superconductor (LTS) bilayer (with critical HTS and LTS temperatures T (c) and T'(c), respectively), separated by a thin (d (M) = 5-20 nm) interlayer of LaMnO(3), La(0.7)Ca(0.3)MnO(3), or La(0.7)Sr(0.3)MnO(3) manganite have been studied. The electric resistance and magnetic properties of individual (evaporated directly onto the substrate) manganite films and related hybrid herostructures have been measured. Based on quasi-classical equations, analytical expressions for the conductivity of herostructures at T a parts per thousand currency sign T'(c) are obtained in the case of a low-transparency superconductor/manganite interface. It is established that the conductivity of heterostructures is determined by the proximity effect (related to the penetration of a condensate wavefunction from the Nb/Au bilayer to manganite) and depends strongly on interface transparency. At low temperatures (T a parts per thousand(a) T (c)'), the conductivity peaks are found at voltages determined by the exchange field of the manganite interlayer. At T (c)'
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| 6. |
- Demidov, V. V., et al.
(författare)
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Magnetic Anisotropy of Strained Epitaxial Manganite Films
- 2011
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Ingår i: Journal of Experimental and Theoretical Physics. - : Pleiades Publishing Ltd. - 1090-6509 .- 1063-7761. ; 112:5, s. 825-832
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Tidskriftsartikel (refereegranskat)abstract
- The in-plane magnetic anisotropy of epitaxial La(0.7)Sr(0.3)MnO(3) (LSMO) films is studied at room temperature by the following three independent techniques: magnetooptical Kerr effect, ferromagnetic resonance at a frequency of 9.61 GHz, and recording of absorption spectra of electromagnetic radiation at a frequency of 290.6 MHz. The films are deposited onto NdGaO(3) (NGO) substrates in which the (110) NGO plane is tilted at an angle of 0-25.7 degrees to the substrate plane. The uniaxial magnetic anisotropy induced by the strain of the film is found to increase with the tilt angle of the (110) NGO plane. A model is proposed to describe the change in the magnetic anisotropy energy with the tilt angle. A sharp increase in the radio-frequency absorption in a narrow angular range of a dc magnetic field near a hard magnetization axis is detected The anisotropy parameters of the LSMO films grown on (110) NGO, (001) SrTiO(3), and (001)[(LaAlO(3))(0.3) + (Sr(2)AlTaO(6))(0.7)] substrates are compared.
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| 7. |
- Ovsyannikov, Gennady, 1948, et al.
(författare)
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Magnetotransport characteristics of strained La0.7Sr0.3MnO3 epitaxial manganite films
- 2009
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Ingår i: Journal of Experimental and Theoretical Physics. - 1090-6509 .- 1063-7761. ; 108:1, s. 48-55
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Tidskriftsartikel (refereegranskat)abstract
- The electrical and magnetic characteristics of La0.7Sr0.3MnO3 (LSMO) epitaxial manganite films are investigated by different methods under conditions when the crystal structure is strongly strained as a result of mismatch between the lattice parameters of the LSMO crystal and the substrate. Substrates with lattice parameters larger and smaller than the nominal lattice parameter of the LSMO crystal are used in experiments. It is shown that the behavior of the temperature dependence of the electrical resistance for the films in the low-temperature range does not depend on the strain of the film and agrees well with the results obtained from the calculations with allowance made for the interaction of electrons with magnetic excitations in the framework of the double-exchange model for systems with strongly correlated electronic states. Investigations of the magneto- optical Kerr effect have revealed that an insignificant (0.3%) orthorhombic distortion of the cubic lattice in the plane of the NdGaO3(110) substrate leads to uniaxial anisotropy of the magnetization of the film, with the easy-magnetization axis lying in the substrate plane. However, LSMO films on substrates (((LaAlO3)(0.3)+(Sr2AlTaO6)(0.7))(001)) ensuring minimum strain of the films exhibit a biaxial anisotropy typical of cubic crystals. The study of the ferromagnetic resonance lines at a frequency of 9.76 GHz confirms the results of magnetooptical investigations and indicates that the ferromagnetic phase in the LSMO films is weakly inhomogeneous.
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| 8. |
- Petrzhik, A. M., et al.
(författare)
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Electron Transport in Manganite Bicrystal Junctions
- 2013
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Ingår i: Physics of the Solid State. - : Pleiades Publishing Ltd. - 1063-7834 .- 1090-6460. ; 55:4, s. 759-764
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Tidskriftsartikel (refereegranskat)abstract
- The transport and magnetic properties of junctions created in La0.67Sr0.33MnO3 thin films epitaxially grown on substrates with a bicrystal boundary have been investigated. In tilted neodymium gallate bicrystal substrates, the NdGaO3(110) planes are inclined at angles of 12 degrees and 38 degrees. The temperature dependences of the electrical resistance, magnetoresistance, and differential conductance of the junctions at different voltages have been measured and analyzed. It has been found that the magnetoresistance and electrical resistance of the junction significantly increase with an increase in the misorientation angle, even though the misorientation of the easy magnetization axes remains nearly unchanged. The ratio of the spin-dependent and spin-independent contributions to the conductance of the bicrystal junction increases by almost an order of magnitude with an increase in the misorientation angle from 12 degrees to 38 degrees. The magnetoresistance of the junction increases with decreasing temperature, which is most likely associated with an increase of the magnetic polarization of the electrons. It has been shown that, at low (liquid-helium) temperatures, the conductance depends on the voltage V according to the law V-1/2, which indicates the dominant contribution from the electron-electron interaction to the electrical resistance of the junction. An increase in the temperature leads to a decrease in this contribution and an increase in the contribution proportional to V-3/2, which is characteristic of the mechanism involving inelastic spin scattering by surface antiferromagnetic magnons.
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| 9. |
- Petrzhik, A. M., et al.
(författare)
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Spin-dependent electron transport in manganite bicrystal junctions
- 2012
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Ingår i: Journal of Experimental and Theoretical Physics. - 1090-6509 .- 1063-7761. ; 115:5, s. 876-884
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Tidskriftsartikel (refereegranskat)abstract
- Magnetic bicrystal films and junctions of magnetic La0.67Sr0.33MnO3 (LSMO) and La0.67Ca0.33MnO3 (LCMO) films epitaxially grown on NdGaO3 substrates with the (110) planes of their two parts misoriented (tilted) at angles of 12A degrees, 22A degrees, 28A degrees, and 38A degrees are investigated. For comparison, bicrystal boundaries with a 90A degrees misorientation of the axes of the NdGaO3 (110) planes were fabricated. The directions of the axes and the magnetic anisotropy constants of the films on both sides of the boundary are determined by two independent techniques of magnetic resonance spectroscopy. The magnetic misorientation of the axes in the substrate plane has been found to be much smaller than the crystallographic misorientation for tilted bicrystal boundaries, while the crystallographic and magnetic misorientation angles coincide for boundaries with rotation of the axes. An increase in the magnetoresistance and characteristic resistance of bicrystal junctions with increasing misorientation angle was observed experimentally. The magnetoresistance of bicrystal junctions has been calculated by taking into account the uniaxial anisotropy, which has allowed the contributions from the tunneling and anisotropic magnetoresistances to be separated. The largest tunneling magnetoresistance was observed on LCMO bicrystal junctions, in which the characteristic resistance of the boundary is higher than that in LSMO boundaries.
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| 10. |
- Rypdal, K., et al.
(författare)
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Non-equilibrium quasi-stationary states in a magnetized plasma
- 2003
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Ingår i: Nonlinear processes in geophysics. - : Copernicus GmbH. - 1023-5809 .- 1607-7946. ; 10:02-jan, s. 139-149
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Tidskriftsartikel (refereegranskat)abstract
- Non-equilibrium quasi-stationary states resulting from curvature driven interchange instabilities and driftwave instabilities in a low beta, weakly ionized, magnetized plasma are investigated in the context of laboratory experiments in a toroidal configuration. Analytic modelling, numerical simulations and experimental results are discussed with emphasis on identifying the unstable modes and understanding the physics of anomalous particle and energy fluxes and their linkage to self-organized pressure profiles.
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