44 research outputs found
Relationship between Density and Biogenic Opal in Sediments from Sites 658 and 660
At Site 658, and especially at Site 660, sediments rich in biogenic
opal were recovered. The fractions of biogenic silica, biogenic
carbonate, and terrigenous material vary throughout the
entire sequence at these sites (see chapters for Sites 658 and 660,
this volume).
At Site 660, biogenic-opal contents up to 100% are common
in Eocene sediments. In studying these opal-rich sediments, a
rapid method for estimating biogenic opal published by Mann
and Muller (1980) was found useful. These authors applied an
X-ray method which measures the height of a broad, diffuse reflection
band of opal extending from about 15° to 32° 20, with
a maximum at about 22° 20 (i.e., 4.04A) (Fig. 1, IB).
Furthermore, this paper describes another method for estimating
variations in the biogenic-opal content by using grain
density. Grain density (p) can easily be determined by measuring
the weight (G) and the volume (V) of the dry sediment, where p
= G/P7g/cm3)
Pattern recognition with a magnon-scattering reservoir
Magnons are elementary excitations in magnetic materials and undergo
nonlinear multimode scattering processes at large input powers. In experiments
and simulations, we show that the interaction between magnon modes of a
confined magnetic vortex can be harnessed for pattern recognition. We study the
magnetic response to signals comprising sine wave pulses with frequencies
corresponding to radial mode excitations. Three-magnon scattering results in
the excitation of different azimuthal modes, whose amplitudes depend strongly
on the input sequences. We show that recognition rates above 95\% can be
attained for four-symbol sequences using the scattered modes, with strong
performance maintained with the presence of amplitude noise in the inputs
Tailoring crosstalk between localized 1D spin-wave nanochannels using focused ion beams
1D spin-wave conduits are envisioned as nanoscale components of
magnonics-based logic and computing schemes for future generation electronics.
`A-la-carte methods of versatile control of the local magnetization dynamics in
such nanochannels are highly desired for efficient steering of the spin waves
in magnonic devices. Here, we present a study of localized dynamical modes in
1-m-wide Permalloy conduits probed by microresonator ferromagnetic
resonance technique. We clearly observe the lowest-energy edge mode in the
microstrip after its edges were finely trimmed by means of focused Ne ion
irradiation. Furthermore, after milling the microstrip along its long axis by
focused ion beams, creating consecutively 50 and 100 nm gaps,
additional resonances emerge and are attributed to modes localized at the inner
edges of the separated strips. To visualize the mode distribution, spatially
resolved Brillouin light scattering microscopy was used showing an excellent
agreement with the ferromagnetic resonance data and confirming the mode
localization at the outer/inner edges of the strips depending on the magnitude
of the applied magnetic field. Micromagnetic simulations confirm that the
lowest-energy modes are localized within 15-nm-wide regions at the edges
of the strips and their frequencies can be tuned in a wide range (up to 5 GHz)
by changing the magnetostatic coupling (i.e. spatial separation) between the
microstrips.Comment: 10 pages, 4 figure
Genetic polymorphisms of manganese-superoxide dismutase and glutathione-S-transferase in chronic alcoholic pancreatitis
Chronic alcohol consumption is a major risk factor for the development of chronic pancreatitis. However, chronic pancreatitis occurs only in a minority of heavy drinkers. This variability may be due to yet unidentified genetic factors. Several enzymes involved in the degradation of reactive oxidants and xenobiotics, such as glutathione-S-transferase P1 (GSTP1) and manganese-superoxide dismutase (MnSOD) reveal functional polymorphisms that affect the antioxidative capacity and may therefore modulate the development of chronic pancreatitis and long-term complications like endocrine and exocrine pancreatic insufficiency. Two functional polymorphisms of the MnSOD and the GSTP1 gene were assessed by polymerase chain reaction and restriction fragment length polymorphism in 165 patients with chronic alcoholic pancreatitis, 140 alcoholics without evidence of pancreatic disease and 160 healthy control subjects. The distribution of GSTP1 and MnSOD genotypes were in Hardy-Weinberg equilibrium in the total cohort. Genotype and allele frequencies for both genes were not statistically different between the three groups. Although genotype MnSOD Ala/Val was seemingly associated with the presence of exocrine pancreatic insufficiency, this subgroup was too small and the association statistically underpowered. None of the tested genotypes affected the development of endocrine pancreatic insufficiency. Polymorphisms of MnSOD and GSTP1 are not associated with chronic alcoholic pancreatitis. The present data emphasize the need for stringently designed candidate gene association studies with well-characterized cases and controls and sufficient statistical power to exclude chance observation
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Magnetization Dynamics of an Individual Single-Crystalline Fe-Filled Carbon Nanotube
The magnetization dynamics of individual Fe-filled multiwall carbon-nanotubes (FeCNT), grown by chemical vapor deposition, are investigated by microresonator ferromagnetic resonance (FMR) and Brillouin light scattering (BLS) microscopy and corroborated by micromagnetic simulations. Currently, only static magnetometry measurements are available. They suggest that the FeCNTs consist of a single-crystalline Fe nanowire throughout the length. The number and structure of the FMR lines and the abrupt decay of the spin-wave transport seen in BLS indicate, however, that the Fe filling is not a single straight piece along the length. Therefore, a stepwise cutting procedure is applied in order to investigate the evolution of the ferromagnetic resonance lines as a function of the nanowire length. The results show that the FeCNT is indeed not homogeneous along the full length but is built from 300 to 400 nm long single-crystalline segments. These segments consist of magnetically high quality Fe nanowires with almost the bulk values of Fe and with a similar small damping in relation to thin films, promoting FeCNTs as appealing candidates for spin-wave transport in magnonic applications. © 2019 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei