1,200 research outputs found
Noninvasive detection of high-risk adenomas using stool-derived eukaryotic RNA sequences as biomarkers
Incommensurate itinerant antiferromagnetic excitations and spin resonance in the FeTeSe superconductor
We report on inelastic neutron scattering measurements that find
incommensurate itinerant like magnetic excitations in the normal state of
superconducting FeTeSe (\Tc=14K) at wave-vector
with =0.09(1). In
the superconducting state only the lower energy part of the spectrum shows
significant changes by the formation of a gap and a magnetic resonance that
follows the dispersion of the normal state excitations. We use a four band
model to describe the Fermi surface topology of iron-based superconductors with
the extended symmetry and find that it qualitatively captures the
salient features of these data.Comment: 7 pages and 5 figure
Noise Correlations in a Coulomb Blockaded Quantum Dot
We report measurements of current noise auto- and cross-correlation in a
tunable quantum dot with two or three leads. As the Coulomb blockade is lifted
at finite source-drain bias, the auto-correlation evolves from super-Poissonian
to sub-Poissonian in the two-lead case, and the cross-correlation evolves from
positive to negative in the three-lead case, consistent with transport through
multiple levels. Cross-correlations in the three-lead dot are found to be
proportional to the noise in excess of the Poissonian value in the limit of
weak output tunneling
The distribution of long-chain n-alkan-2-ones in peat can be used to infer past changes in pH
Long-chain (C21-C33) n-alkan-2-ones are biomarkers ubiquitous in peat deposits. However, their paleoenvironmental significance lacks constraints. Here we evaluate the influence pH exerts on the occurrence of long-chain n-alkan-2-ones in Chinese peats. A comparison of the distribution in a collection (n= 65) of modern peat samples with different pH (pH values 4.4-8.6) from China demonstrates that their distribution is significantly different in acid compared to alkaline peat. This difference can be explained by the pH control on the conversion of n-alkan-2-one precursor compounds (n-alkanes and fatty acids). Transfer functions between pH and n-alkan-2-one ratios were established using linear and logarithmic regression models. We then applied these proxies to reconstruct variations of paleo-pH in the Dajiuhu peat sequence to identify the history of peatland acidification over the last 13 kyr. We find significant changes in paleo-pH during the deglaciation/early Holocene and relate these to times of dry climate in the region. The drought-induced peat acidification is supported by observations from modern drying events in the peatland. We propose that long-chain n-alkan-2-ones in peats have potential to trace paleo-pH changes across the deglaciation and Holocene, although further research from different peatlands and time periods is still needed
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