205 research outputs found
Indication of intrinsic spin Hall effect in 4d and 5d transition metals
We have investigated spin Hall effects in 4 and 5 transition metals,
Nb, Ta, Mo, Pd and Pt, by incorporating the spin absorption method in the
lateral spin valve structure; where large spin current preferably relaxes into
the transition metals, exhibiting strong spin-orbit interactions. Thereby
nonlocal spin valve measurements enable us to evaluate their spin Hall
conductivities. The sign of the spin Hall conductivity changes systematically
depending on the number of electrons. This tendency is in good agreement
with the recent theoretical calculation based on the intrinsic spin Hall
effect.Comment: 5 pages, 4 figure
Extrinsic Spin Hall Effect Induced by Iridium Impurities in Copper
We study the extrinsic spin Hall effect induced by Ir impurities in Cu by
injecting a pure spin current into a CuIr wire from a lateral spin valve
structure. While no spin Hall effect is observed without Ir impurity, the spin
Hall resistivity of CuIr increases linearly with the impurity concentration.
The spin Hall angle of CuIr, % throughout the concentration
range between 1% and 12%, is practically independent of temperature. These
results represent a clear example of predominant skew scattering extrinsic
contribution to the spin Hall effect in a nonmagnetic alloy.Comment: 5 pages, 4 figure
Observation of thermodynamics originating from a mixed-spin ferromagnetic chain
We present a model compound that forms a mixed-spin ferromagnetic chain. Our
material design, based on the organic radicals, affords a verdazyl-based
complex (p-Py-V)2[Mn(hfac)2]. The molecular orbital calculations of the
compound indicate the formation of a mixed spin-(1/2, 1/2, 5/2) ferromagnetic
chain. The temperature dependence of magnetic susceptibility reveals its
ferromagnetic behavior. The magnetic specific heat exhibits a double-peak
structure and indicates a phase transition at the low-temperature peak. The
observed characteristics are explained using the quantum Monte Carlo
calculations. Furthermore, the modified spin-wave theory verifies that the
double-peak structure of the specific heat significantly reflects the relative
ration of the acoustic excitation band and the optical excitation gap
Layer thickness dependence of the current induced effective field vector in Ta|CoFeB|MgO
The role of current induced effective magnetic field in ultrathin magnetic
heterostructures is increasingly gaining interest since it can provide
efficient ways of manipulating magnetization electrically. Two effects, known
as the Rashba spin orbit field and the spin Hall spin torque, have been
reported to be responsible for the generation of the effective field. However,
quantitative understanding of the effective field, including its direction with
respect to the current flow, is lacking. Here we show vector measurements of
the current induced effective field in Ta|CoFeB|MgO heterostructrures. The
effective field shows significant dependence on the Ta and CoFeB layers'
thickness. In particular, 1 nm thickness variation of the Ta layer can result
in nearly two orders of magnitude difference in the effective field. Moreover,
its sign changes when the Ta layer thickness is reduced, indicating that there
are two competing effects that contribute to the effective field. The relative
size of the effective field vector components, directed transverse and parallel
to the current flow, varies as the Ta thickness is changed. Our results
illustrate the profound characteristics of just a few atomic layer thick metals
and their influence on magnetization dynamics
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Formation age of the lunar crater Giordano Bruno
Using the Terrain Camera onboard the Japanese lunar explorer, SELENE (Kaguya), we obtained new high-resolution images of the 22-kilometer-diameter lunar crater Giordano Bruno. Based on crater size-frequency measurements of small craters (<200 m in diameter) superposed on its continuous ejecta, the formation age of Giordano Bruno is estimated to be 1 to 10 Ma. This is constructive evidence against the crater's medieval age formation hypothesis.The Meteoritics & Planetary Science archives are made available by the Meteoritical Society and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202
Cross calibration between Hayabusa2/ONC-T and OSIRIS-REx/MapCam for comparative analyses between asteroids Ryugu and Bennu
Proximity observations of (162173) Ryugu by the telescopic Optical Navigation
Camera onboard Hayabusa2 and (101955) Bennu by MapCam onboard Origins, Spectral
Interpretation, Resource Identification, and Security-Regolith Explorer found
opposite spectral trends of space weathering on these carbonaceous asteroids.
Whether the space weathering trends on these asteroids evolved from the same
starting spectra would place an important constraint for understanding their
relation. However, systematic error between data obtained by the two imagers
needed to be reduced for accurate comparison. To resolve this problem, we cross
calibrated albedo and color data using the Moon as the common standard. We show
that the cross-calibrated reflectance can be obtained by upscaling the
pre-cross-calibrated reflectance of Bennu by 12 +/- 2% at v-band, reducing the
systematic errors down to 2%. The cross-calibrated data show that Bennu is
brighter by 16 +/- 2% at v-band and bluer in spectral slope by 0.19 +/- 0.05
(/um) than Ryugu. The spectra of fresh craters on Ryugu and Bennu before cross
calibration appeared to follow two parallel trend lines with offset, but they
converged to a single trend after cross calibration. Such a
post-cross-calibration perspective raise the possibility that Ryugu and Bennu
evolved from materials with similar visible spectra but evolved in diverging
directions by space weathering. The divergent evolution can be caused by the
difference in space weathering dose/process and/or composition of the starting
material. Thus, comparing the composition of samples returned from Ryugu and
Bennu may change the way we interpret the spectral variation of C-complex
asteroids
Protein profiling in hepatocellular carcinoma by label-free quantitative proteomics in two west african populations.
Background Hepatocellular Carcinoma is the third most common cause of cancer related death worldwide, often diagnosed by measuring serum AFP; a poor performance stand-alone biomarker. With the aim of improving on this, our study focuses on plasma proteins identified by Mass Spectrometry in order to investigate and validate differences seen in the respective proteomes of controls and subjects with LC and HCC. Methods Mass Spectrometry analysis using liquid chromatography electro spray ionization quadrupole time-of-flight was conducted on 339 subjects using a pooled expression profiling approach. ELISA assays were performed on four significantly differentially expressed proteins to validate their expression profiles in subjects from the Gambia and a pilot group from Nigeria. Results from this were collated for statistical multiplexing using logistic regression analysis. Results Twenty-six proteins were identified as differentially expressed between the three subject groups. Direct measurements of four; hemopexin, alpha-1-antitrypsin, apolipoprotein A1 and complement component 3 confirmed their change in abundance in LC and HCC versus control patients. These trends were independently replicated in the pilot validation subjects from Nigeria. The statistical multiplexing of these proteins demonstrated performance comparable to or greater than ALT in identifying liver cirrhosis or carcinogenesis. This exercise also proposed preliminary cut offs with achievable sensitivity, specificity and AUC statistics greater than reported AFP averages. Conclusions The validated changes of expression in these proteins have the potential for development into high-performance tests usable in the diagnosis and or monitoring of HCC and LC patients. The identification of sustained expression trends strengthens the suggestion of these four proteins as worthy candidates for further investigation in the context of liver disease. The statistical combinations also provide a novel inroad of analyses able to propose definitive cut-offs and combinations for evaluation of performance
Mechanisms of cerebellar tonsil herniation in patients with Chiari malformations as guide to clinical management
Background The pathogenesis of Chiari malformations is incompletely understood. We tested the hypothesis that different etiologies have different mechanisms of cerebellar tonsil herniation (CTH), as revealed by posterior cranial fossa (PCF) morphology. Methods In 741 patients with Chiari malformation type I (CM-I) and 11 patients with Chiari malformation type II (CM-II), the size of the occipital enchondrium and volume of the PCF (PCFV) were measured on reconstructed 2D-CT and MR images of the skull. Measurements were compared with those in 80 age- and sex-matched healthy control individuals, and the results were correlated with clinical findings. Results Significant reductions of PCF size and volume were present in 388 patients with classical CM-I, 11 patients with CM-II, and five patients with CM-I and craniosynostosis. Occipital bone size and PCFV were normal in 225 patients with CM-I and occipitoatlantoaxial joint instability, 55 patients with CM-I and tethered cord syndrome (TCS), 30 patients with CM-I and intracranial mass lesions, and 28 patients with CM-I and lumboperitoneal shunts. Ten patients had miscellaneous etiologies. The size and area of the foramen magnum were significantly smaller in patients with classical CM-I and CM-I occurring with craniosynostosis and significantly larger in patients with CM-II and CM-I occurring with TCS. Conclusions Important clues concerning the pathogenesis of CTH were provided by morphometric measurements of the PCF. When these assessments were correlated with etiological factors, the following causal mechanisms were suggested: (1) cranial constriction; (2) cranial settling; (3) spinal cord tethering; (4) intracranial hypertension; and (5) intraspinal hypotension
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