208 research outputs found
Invasive Plants Are a Valuable Alternate Protein Source and Can Contribute to Meeting Climate Change Targets
This work was funded by the Scottish Government through RESAS as part of its strategic research programme. We would like to thank William Rees and Teresa Grohmann for their time in helping with preparation of the manuscript. Jacqueline Wallace (Rowett Institute) and Robin Walker (SRUC) for providing plant samples. Donna Henderson and Jodie Park for technical assistance in NSP measurements. Susan Anderson for technical assistance in amino acid profiling. Gary Duncan and Lorraine Scobbie for technical assistance in phenolic profiling. Lisa Guerrier, Salomé Leveque (IUT- Clermont-Ferrand, France), who assisted and observed procedures as part of their lab-skill training. We would also like to thank Graham Horgan (BIOSS, Rowett Institute) for advise on the statistical analysis. We would like to thank the NHS for its incredible commitment to keeping us safe during these harsh times.Peer reviewedPublisher PD
Interplay of chiral and helical states in a Quantum Spin Hall Insulator lateral junction
We study the electronic transport across an electrostatically-gated lateral
junction in a HgTe quantum well, a canonical 2D topological insulator, with and
without applied magnetic field. We control carrier density inside and outside a
junction region independently and hence tune the number and nature of 1D edge
modes propagating in each of those regions. Outside the 2D gap, magnetic field
drives the system to the quantum Hall regime, and chiral states propagate at
the edge. In this regime, we observe fractional plateaus which reflect the
equilibration between 1D chiral modes across the junction. As carrier density
approaches zero in the central region and at moderate fields, we observe
oscillations in resistance that we attribute to Fabry-Perot interference in the
helical states, enabled by the broken time reversal symmetry. At higher fields,
those oscillations disappear, in agreement with the expected absence of helical
states when band inversion is lifted.Comment: 5 pages, 4 figures, supp. ma
Electron-nuclear interaction in 13C nanotube double quantum dots
For coherent electron spins, hyperfine coupling to nuclei in the host
material can either be a dominant source of unwanted spin decoherence or, if
controlled effectively, a resource allowing storage and retrieval of quantum
information. To investigate the effect of a controllable nuclear environment on
the evolution of confined electron spins, we have fabricated and measured
gate-defined double quantum dots with integrated charge sensors made from
single-walled carbon nanotubes with a variable concentration of 13C (nuclear
spin I=1/2) among the majority zero-nuclear-spin 12C atoms. Spin-sensitive
transport in double-dot devices grown using methane with the natural abundance
(~ 1%) of 13C is compared with similar devices grown using an enhanced (~99%)
concentration of 13C. We observe strong isotope effects in spin-blockaded
transport, and from the dependence on external magnetic field, estimate the
hyperfine coupling in 13C nanotubes to be on the order of 100 micro-eV, two
orders of magnitude larger than anticipated theoretically. 13C-enhanced
nanotubes are an interesting new system for spin-based quantum information
processing and memory, with nuclei that are strongly coupled to gate-controlled
electrons, differ from nuclei in the substrate, are naturally confined to one
dimension, lack quadrupolar coupling, and have a readily controllable
concentration from less than one to 10^5 per electron.Comment: supplementary discussion at http://marcuslab.harvard.edu/13CSupp.pd
Developing and assessing a new web-based tapping test for measuring distal movement in Parkinson's disease: a Distal Finger Tapping test
Disability in Parkinson's disease (PD) is measured by standardised scales including the MDS-UPDRS, which are subject to high inter and intra-rater variability and fail to capture subtle motor impairment. The BRadykinesia Akinesia INcoordination (BRAIN) test is a validated keyboard tapping test, evaluating proximal upper-limb motor impairment. Here, a new Distal Finger Tapping (DFT) test was developed to assess distal upper-limb function. Kinetic parameters of the test include kinesia score (KS20, key taps over 20 s), akinesia time (AT20, mean dwell-time on each key) and incoordination score (IS20, variance of travelling time between key taps). To develop and evaluate a new keyboard-tapping test for objective and remote distal motor function in PD patients. The DFT and BRAIN tests were assessed in 55 PD patients and 65 controls. Test scores were compared between groups and correlated with the MDS-UPDRS-III finger tapping sub-scores. Nine additional PD patients were recruited for monitoring motor fluctuations. All three parameters discriminated effectively between PD patients and controls, with KS20 performing best, yielding 79% sensitivity for 85% specificity; area under the receiver operating characteristic curve (AUC) = 0.90. A combination of DFT and BRAIN tests improved discrimination (AUC = 0.95). Among three parameters, KS20 showed a moderate correlation with the MDS-UPDRS finger-tapping sub-score (Pearson's r = - 0.40, p = 0.002). Further, the DFT test detected subtle changes in motor fluctuation states which were not reflected clearly by the MDS-UPDRS-III finger tapping sub-scores. The DFT test is an online tool for assessing distal movements in PD, with future scope for longitudinal monitoring of motor complications
Gorse (Ulex europeaus) wastes with 5,6-dimethyl benzimidazole supplementation can support growth of vitamin B12 producing commensal gut microbes
Open Access via the PLOS Agreement. Funding: This research was funded by the Scottish Government through Rural and Environmental Science and Analytical Services (RESAS) as part of its strategic funding programme. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewe
Hrp Mutant of Pseudomonas syringae pv phaseolicola Induces Cell Wall Alterations but Not Membrane Damage Leading to the Hypersensitive Reaction in Lettuce
Relaxation and Dephasing in a Two-Electron 13C Nanotube Double Quantum Dot
We use charge sensing of Pauli blockade (including spin and isospin) in a
two-electron 13C nanotube double quantum dot to measure relaxation and
dephasing times. The relaxation time, T1, first decreases with parallel
magnetic field then goes through a minimum in a field of 1.4 T. We attribute
both results to the spin-orbit-modified electronic spectrum of carbon
nanotubes, which suppresses hyperfine mediated relaxation and enhances
relaxation due to soft phonons. The inhomogeneous dephasing time, T2*, is
consistent with previous data on hyperfine coupling strength in 13C nanotubes.Comment: related papers at http://marcuslab.harvard.ed
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Electron–Nuclear Interaction in Nanotube Double Quantum Dots
For coherent electron spins, hyperfine coupling to nuclei in the host material can either be a dominant source of unwanted spin decoherence or, if controlled effectively, a resource enabling storage and retrieval of quantum information. To investigate the effect of a controllable nuclear environment on the evolution of confined electron spins, we have fabricated and measured gate-defined double quantum dots with integrated charge sensors made from single-walled carbon nanotubes with a variable concentration of (nuclear spin among the majority zero-nuclear-spin atoms. We observe strong isotope effects in spin-blockaded transport, and from the magnetic field dependence estimate the hyperfine coupling in nanotubes to be of the order of , two orders of magnitude larger than anticipated. -enhanced nanotubes are an interesting system for spin-based quantum information processing and memory: the nuclei differ from those in the substrate, are naturally confined to one dimension, lack quadrupolar coupling and have a readily controllable concentration from less than one to per electron.Physic
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Relaxation and Dephasing in a Two-Electron Nanotube Double Quantum Dot
We use charge sensing of Pauli blockade (including spin and isospin) in a two-electron nanotube double quantum dot to measure relaxation and dephasing times. The relaxation time first decreases with a parallel magnetic field and then goes through a minimum in a field of . We attribute both results to the spin-orbit-modified electronic spectrum of carbon nanotubes, which at high field enhances relaxation due to bending-mode phonons. The inhomogeneous dephasing time is consistent with previous data on hyperfine coupling strength in nanotubes.PhysicsOther Research Uni
Gauge-theoretic invariants for topological insulators: A bridge between Berry, Wess-Zumino, and Fu-Kane-Mele
We establish a connection between two recently-proposed approaches to the
understanding of the geometric origin of the Fu-Kane-Mele invariant
, arising in the context of 2-dimensional
time-reversal symmetric topological insulators. On the one hand, the
invariant can be formulated in terms of the Berry connection and
the Berry curvature of the Bloch bundle of occupied states over the Brillouin
torus. On the other, using techniques from the theory of bundle gerbes it is
possible to provide an expression for containing the square root
of the Wess-Zumino amplitude for a certain -valued field over the
Brillouin torus.
We link the two formulas by showing directly the equality between the above
mentioned Wess-Zumino amplitude and the Berry phase, as well as between their
square roots. An essential tool of independent interest is an equivariant
version of the adjoint Polyakov-Wiegmann formula for fields , of which we provide a proof employing only basic homotopy theory and
circumventing the language of bundle gerbes.Comment: 23 pages, 1 figure. To appear in Letters in Mathematical Physic
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