205 research outputs found
Guiding and Trapping Electron Spin Waves in Atomic Hydrogen Gas
We present a high magnetic field study of electron spin waves in atomic
hydrogen gas compressed to high densities of 10^18 cm^-3 at temperatures
ranging from 0.26 to 0.6 K. We observed a variety of spin wave modes caused by
the identical spin rotation effect with strong dependence on the spatial
profile of the polarizing magnetic field. We demonstrate confinement of these
modes in regions of strong magnetic field and manipulate their spatial
distribution by changing the position of the field maximum.Comment: 5 pages, 4 figure
Guiding and trapping of electron spin waves in atomic hydrogen gas
We present a high magnetic field study of electron spin waves in atomic hydrogen gas compressed to high densities of ā¼1018cm -3 at temperatures ranging from 0.26 to 0.6 K. We observed a variety of spin wave modes caused by the identical spin rotation effect with strong dependence on the spatial profile of the polarizing magnetic field. We demonstrate confinement of these modes in regions of strong magnetic field and manipulate their spatial distribution by changing the position of the field maximum. Ā© 2012 American Physical Society
Searching for magnetostatic modes in spin-polarized atomic hydrogen
We consider a possibility of the magnetostatic type spin waves driven by a long-range magnetic dipole interactions, to account for the peaks in the ESR spectra observed in our previous work (Lehtonen et al 2018 New J. Phys. 20 055010). The Walker equation for magnetostatic modes is solved for a cylinder of atomic hydrogen, first in a uniform magnetic field and second in a linearly decreasing magnetic field. The frequency behavior of the solved modes with length of the cylinder and density of the gas is compared to experimental data. We conclude that magnetostatic modes are unlikely to account for the observed modulations of ESR spectra
Bose-einstein condensation of magnons in atomic hydrogen gas
Ā© 2015 American Physical Society. We report on experimental observation of Bose-Einstein condensation (BEC)-like behavior of quantized electron spin waves (magnons) in a dense gas of spin-polarized atomic hydrogen. The magnons are trapped and controlled with inhomogeneous magnetic fields and described by a Schrƶdinger-like wave equation, in analogy to the BEC experiments with neutral atoms. We have observed the appearance of a sharp feature in the ESR spectrum displaced from the normal spin wave spectrum. We believe that this observation corresponds to a sudden growth of the ground-state population of the magnons and emergence of their spontaneous coherence for hydrogen gas densities exceeding a critical value, dependent on the trapping potential. We interpret the results as a BEC of nonequilibrium magnons which were formed by applying the rf power
Bose-Einstein Condensation of Magnons in Atomic Hydrogen Gas
We report on experimental observation of BEC-like behaviour of quantized
electron spin waves (magnons) in a dense gas of spin polarized atomic hydrogen.
The magnons are trapped and controlled with inhomogeneous magnetic fields, and
described by a Schr\"odinger-like wave equation, in analogy to the BEC
experiments with neutral atoms. We have observed the appearance of a sharp
feature in the ESR spectrum displaced from the normal spin wave spectrum. We
believe that this observation corresponds to a sudden growth of the ground
state population of the magnons and emergence of their spontaneous coherence
for hydrogen gas densities exceeding a critical value, dependent on the
trapping potential. We interpret the results as a BEC of non-equilibrium
magnons which were formed by applying the rf power.Comment: 5 pages, 3 figures Supplemental material: 3 pages, 3 figures.
Accepted for publication in Physical Review Letter
Bose-Einstein Condensation of Magnons in Atomic Hydrogen Gas
We report on experimental observation of Bose-Einstein condensation (BEC)-like behavior of quantized electron spin waves (magnons) in a dense gas of spin-polarized atomic hydrogen. The magnons are trapped and controlled with inhomogeneous magnetic fields and described by a Schrödinger-like wave equation, in analogy to the BEC experiments with neutral atoms. We have observed the appearance of a sharp feature in the ESR spectrum displaced from the normal spin wave spectrum. We believe that this observation corresponds to a sudden growth of the ground-state population of the magnons and emergence of their spontaneous coherence for hydrogen gas densities exceeding a critical value, dependent on the trapping potential. We interpret the results as a BEC of nonequilibrium magnons which were formed by applying the rf power.</p
Detection and verification of malting quality QTLs using wild barley introgression lines
A malting quality quantitative trait locus (QTL) study was conducted using a set of 39 wild barley introgression lines (hereafter abbreviated with S42ILs). Each S42IL harbors a single marker-defined chromosomal segment from the wild barley accession āISR 42-8ā (Hordeum vulgare ssp. spontaneum) within the genetic background of the elite spring barley cultivar āScarlettā (Hordeum vulgare ssp. vulgare). The aim of the study was (1) to verify genetic effects previously identified in the advanced backcross population S42, (2) to detect new QTLs, and (3) to identify S42ILs exhibiting multiple QTL effects. For this, grain samples from field tests in three different environments were subjected to micro malting. Subsequently, a lineĀ ĆĀ phenotype association study was performed with the S42ILs in order to localize putative QTL effects. A QTL was accepted if the trait value of a particular S42IL was significantly (PĀ <Ā 0.05) different from the recurrent parent as a control, either across all tested environments or in a particular environment. For eight malting quality traits, altogether 40 QTLs were localized, among which 35 QTLs (87.5%) were stable across all environments. Six QTLs (15.0%) revealed a trait improving wild barley effect. Out of 36 QTLs detected in a previous advanced backcross QTL study with the parent BC2DH population S42, 18 QTLs (50.0%) could be verified with the S42IL set. For the quality parameters Ī±-amylase activity and Hartong 45Ā°C, all QTLs assessed in population S42 were verified by S42ILs. In addition, eight new QTL effects and 17 QTLs affecting two newly investigated traits were localized. Two QTL clusters harboring simultaneous effects on eight and six traits, respectively, were mapped to chromosomes 1H and 4H. In future, fine-mapping of these QTL regions will be conducted in order to shed further light on the genetic basis of the most interesting QTLs
Glutathione <em>S</em>-transferase P1 (<em>GSTP1</em>) directly influences platinum drug chemosensitivity in ovarian tumour cell lines
BACKGROUND: Chemotherapy response in ovarian cancer patients is frequently compromised by drug resistance, possibly due to altered drug metabolism. Platinum drugs are metabolised by glutathione S-transferase P1 (GSTP1), which is abundantly, but variably expressed in ovarian tumours. We have created novel ovarian tumour cell line models to investigate the extent to which differential GSTP1 expression influences chemosensitivity. METHODS: Glutathione S-transferase P1 was stably deleted in A2780 and expression significantly reduced in cisplatin-resistant A2780DPP cells using Mission shRNA constructs, and MTT assays used to compare chemosensitivity to chemotherapy drugs used to treat ovarian cancer. Differentially expressed genes in GSTP1 knockdown cells were identified by Illumina HT-12 expression arrays and qRTāPCR analysis, and altered pathways predicted by MetaCore (GeneGo) analysis. Cell cycle changes were assessed by FACS analysis of PI-labelled cells and invasion and migration compared in quantitative Boyden chamber-based assays. RESULTS: Glutathione S-transferase P1 knockdown selectively influenced cisplatin and carboplatin chemosensitivity (2.3- and 4.83-fold change in IC(50), respectively). Cell cycle progression was unaffected, but cell invasion and migration was significantly reduced. We identified several novel GSTP1 target genes and candidate platinum chemotherapy response biomarkers. CONCLUSIONS: Glutathione S-transferase P1 has an important role in cisplatin and carboplatin metabolism in ovarian cancer cells. Inter-tumour differences in GSTP1 expression may therefore influence response to platinum-based chemotherapy in ovarian cancer patients
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