Spatial gradient of dynamic nuclear spin polarization induced by breakdown of quantum Hall effect

We studied spatial distribution of dynamic nuclear polarization (DNP) in a Hall-bar device in a breakdown regime of the quantum Hall effect (QHE). We detected nuclear magnetic resonance (NMR) signals from the polarized nuclear spins by measuring the Hall voltage $V_{xy}$ using three pairs of voltage probes attached to the conducting channel of the Hall bar. We find that the amplitude of the NMR signal depends on the position of the Hall voltage probes and that the largest NMR signal is obtained from the pair of probes farthest from the electron-injecting electrode. Combined with results on pump-and-probe measurements, we conclude that the DNP induced by QHE breakdown develops along the electron-drift direction.Comment: 4 pages, 4 figures, accepted for publication in PR

Dynamic nuclear polarization and Knight shift measurements in a breakdown regime of integer quantum Hall effect

Nuclear spins are polarized electrically in a breakdown regime of an odd-integer quantum Hall effect (QHE). Electron excitation to the upper Landau subband with the opposite spin polarity flips nuclear spins through the hyperfine interaction. The polarized nuclear spins reduce the spin-splitting energy and accelerate the QHE breakdown. The Knight shift of the nuclear spins is also measured by tuning electron density during the irradiation of radio-frequency magnetic fields.Comment: 3 pages, 2 figures, EP2DS-1

Far-infrared rays control prostate cancer cells _in vitro_ and _in vivo_

We introduce a new effective method to control hormone refractory prostate cancer cells by using an activated rubber/resin form (RB), far-infrared ray emitter, with or without sodium butyrate (SB). The growth of three human prostate cancer cell lines (Du145, PC-3 and LNCaP) was suppressed _in vitro_ and _in vivo_ by using RB, and the cells were eradicated with RB + 3 mM SB. G1 arrest and apoptotic pathway proteins were induced by RB with intensified expressions of apoptosis - related mRNA on cDNA microarray. RB radiates the infra-red rays of the 4 to 25 [mu]m wavelengths to an object which exert a favorable influence on a cancer control. These results may render us a new therapeutic modality in hormone refractory prostate cancer

Magnetization dependent current rectification in (Ga,Mn)As magnetic tunnel junctions

We have found that the current rectification effect in triple layer (double barrier) (Ga,Mn)As magnetic tunnel junctions strongly depends on the magnetization alignment. The direction as well as the amplitude of the rectification changes with the alignment, which can be switched by bi-directional spin-injection with very small threshold currents. A possible origin of the rectification is energy dependence of the density of states around the Fermi level. Tunneling density of states in (Ga,Mn)As shows characteristic dip around zero-bias indicating formation of correlation gap, the asymmetry of which would be a potential source of the energy dependent density of states

Intersubband electronic Raman scattering in narrow GaAs single quantum wells dominated by single-particle excitations

We measured resonant Raman scattering by intersubband electronic excitations in GaAs/AlAs single quantum wells (QWs) with well widths ranging from 8.5 to 18 nm. In narrow (less than 10 nm) QWs with sufficiently high electron concentrations, only single-particle excitations (SPEs) were observed in intersubband Raman scattering, which was confirmed by the well-width dependence of Raman spectra. We found characteristic variations in Raman shift and line shape for SPEs with incident photon energy in the narrow QWs.Comment: 5 pages including 4 figure

Molecular characterization of articular cartilage from young adults with femoroacetabular impingement

BACKGROUND: Femoroacetabular impingement is a frequent cause of hip pain and may lead to secondary osteoarthritis, yet little is known about the molecular events linking mechanical hip impingement and articular cartilage degeneration. The first goal of this study was to quantify the expression of inflammatory cytokine and chemokine, matrix-degrading, and extracellular matrix genes in articular cartilage harvested from control hips and hips with femoroacetabular impingement and end-stage osteoarthritis. The second goal was to analyze the relative expression of these genes in articular cartilage harvested at various stages of osteoarthritis. METHODS: Cartilage samples were obtained from thirty-two hips undergoing hip preservation surgery for femoroacetabular impingement or hip arthroplasty. Three control cartilage samples were also analyzed. Specimens were graded intraoperatively with regard to the severity of cartilage damage, the radiographic osteoarthritis grade was recorded, and quantitative RT-PCR (real-time polymerase chain reaction) was performed to determine relative gene expression. RESULTS: Except for interleukin-1β (IL-1β) and CXCL2, the mRNA (messenger RNA) expression of all other chemokine (IL-8, CXCL1, CXCL3, CXCL6, CCL3, and CCL3L1), matrix-degrading (matrix metalloproteinase [MMP]-13 and ADAMTS-4), and structural matrix (COL2A1 [collagen, type II, alpha] and ACAN [aggregan]) genes was higher overall in cartilage from hips with femoroacetabular impingement compared with hips with osteoarthritis and normal controls. The differences reached significance (p ≤ 0.05) for seven of these ten quantified genes, with CXCL3, CXCL6, and COL2A1 being elevated in the femoroacetabular impingement group compared with only the control group and IL-8, CCL3L1, ADAMTS-4, and ACAN being elevated compared with both the osteoarthritis and control groups. When samples were grouped according to the stage of the degenerative cascade, mRNA expression was relatively higher in one of the two middle stages of femoroacetabular impingement (chondromalacia or cleavage/thinning), with the difference reaching significance for IL-8, CXCL2, CXCL3, CCL3L1, and ACAN. ACAN expression was diminished in hips with osteoarthritis compared with femoroacetabular impingement but elevated compared with the control articular cartilage. CONCLUSIONS: Articular cartilage from the impingement zone of hips with femoroacetabular impingement (and particularly those hips in the cleavage/thinning stage) expressed higher levels of certain inflammatory, anabolic, and catabolic genes, representing a heightened metabolic state. CLINICAL RELEVANCE: The articular cartilage from the impingement zone of hips with femoroacetabular impingement was metabolically hyperactive, supporting the concept that such impingement is a structural precursor to hip osteoarthritis