717 research outputs found
Stepwise quantized surface states and delayed Landau level hybridization in Co cluster-decorated BiSbTeSe2 topological insulator devices
In three-dimensional topological insulators (TIs), the nontrivial topology in
their electronic bands casts a gapless state on their solid surfaces, using
which dissipationless TI edge devices based on the quantum anomalous Hall (QAH)
effect and quantum Hall (QH) effect have been demonstrated. Practical TI
devices present a pair of parallel-transport topological surface states (TSSs)
on their top and bottom surfaces. However, due to the no-go theorem, the two
TSSs always appear as a pair and are expected to quantize synchronously.
Quantized transport of a separate Dirac channel is still desirable, but has
never been observed in graphene even after intense investigation over a period
of 13 years, with the potential aim of half-QHE. By depositing Co atomic
clusters, we achieved stepwise quantization of the top and bottom surfaces in
BiSbTeSe2 (BSTS) TI devices. Renormalization group flow diagrams13, 22 (RGFDs)
reveal two sets of converging points (CVPs) in the (Gxy, Gxx) space, where the
top surface travels along an anomalous quantization trajectory while the bottom
surface retains 1/2 e2/h. This results from delayed Landau-level (LL)
hybridization (DLLH) due to coupling between Co clusters and TSS Fermions
Improved Measurement of the Pseudoscalar Decay Constant
We present a new determination of the Ds decay constant, f_{Ds} using 5
million continuum charm events obtained with the CLEO II detector. Our value is
derived from our new measured ratio of widths for Ds -> mu nu/Ds -> phi pi of
0.173+/- 0.021 +/- 0.031. Taking the branching ratio for Ds -> phi pi as (3.6
+/- 0.9)% from the PDG, we extract f_{Ds} = (280 +/- 17 +/- 25 +/- 34){MeV}. We
compare this result with various model calculations.Comment: 23 page postscript file, postscript file also available through
http://w4.lns.cornell.edu/public/CLN
Search for the Decays B^0 -> D^{(*)+} D^{(*)-}
Using the CLEO-II data set we have searched for the Cabibbo-suppressed decays
B^0 -> D^{(*)+} D^{(*)-}. For the decay B^0 -> D^{*+} D^{*-}, we observe one
candidate signal event, with an expected background of 0.022 +/- 0.011 events.
This yield corresponds to a branching fraction of Br(B^0 -> D^{*+} D^{*-}) =
(5.3^{+7.1}_{-3.7}(stat) +/- 1.0(syst)) x 10^{-4} and an upper limit of Br(B^0
-> D^{*+} D^{*-}) D^{*\pm} D^\mp and
B^0 -> D^+ D^-, no significant excess of signal above the expected background
level is seen, and we calculate the 90% CL upper limits on the branching
fractions to be Br(B^0 -> D^{*\pm} D^\mp) D^+
D^-) < 1.2 x 10^{-3}.Comment: 12 page postscript file also available through
http://w4.lns.cornell.edu/public/CLNS, submitted to Physical Review Letter
Sustainable recycling of intact carbon fibres from end-of-service-life composites
A novel method is developed to reclaim carbon fibres from carbon fabric-reinforced cementitious composites. The method takes advantage of an electrically driven chemical reaction in the presence of an aqueous electrolyte solution and an electrical current. This paper presents an experimental programme to investigate the effects of the applied current density, the sodium chloride and nitric acid concentrations in the solution and the temperatures. Both tensile strengths and interfacial shear strengths of the reclaimed carbon fibres were evaluated. Microstructural analyses on the morphologies of the reclaimed carbon fibres were also performed. The proposed method is simple, environmentally friendly and efficient. This method has no size limits on the recycled composites, which indicates the suitability of this approach for large-scale industrial applications. The reclaimed carbon fibres are found to be intact and believed to have great commercial value since the recycling process did not damage their strengths or reduce their dimensions
Technical Note: Evaluation of audiovisual biofeedback smartphone application for respiratory monitoring in radiation oncology
PurposeRadiation dose delivered to targets located near the upper abdomen or thorax are significantly affected by respiratory motion, necessitating large margins, limiting dose escalation. Surrogate motion management devices, such as the Real-time Position Management (RPM™) system (Varian Medical Systems, Palo Alto, CA), are commonly used to improve normal tissue sparing. Alternative to current solutions, we have developed and evaluated the feasibility of a real-time position management system that leverages the motion data from the onboard hardware of Apple iOS devices to provide patients with visual coaching with the potential to improve the reproducibility of breathing as well as improve patient compliance and reduce treatment delivery time.Methods and materialsThe iOS application, coined the Instant Respiratory Feedback (IRF) system, was developed in Swift (Apple Inc., Cupertino, CA) using the Core-Motion library and implemented on an Apple iPhone® devices. Operation requires an iPhone®, a three-dimensional printed arm, and a radiolucent projector screen system for feedback. Direct comparison between IRF, which leverages sensor fusion data from the iPhone®, and RPM™, an optical-based system, was performed on multiple respiratory motion phantoms and volunteers. The IRF system and RPM™ camera tracking marker were placed on the same location allowing for simultaneous data acquisition. The IRF surrogate measurement of displacement was compared to the signal trace acquired using RPM™ with univariate linear regressions and Bland-Altman analysis.ResultsPeriodic motion shows excellent agreement between both systems, and subject motion shows good agreement during regular and irregular breathing motion. Comparison of IRF and RPM™ show very similar signal traces that were significantly related across all phantoms, including those motion with different amplitude and frequency, and subjects' waveforms (all r > 0.9, P < 0.0001). We demonstrate the feasibility of performing four-dimensional cone beam computed tomography using IRF which provided similar image quality as RPM™ when reconstructing dynamic motion phantom images.ConclusionsFeasibility of an iOS application to provide real-time respiratory motion is demonstrated. This system generated comparable signal traces to a commercially available system and offers an alternative method to monitor respiratory motion
A revision of Sanpasaurus yaoi Young, 1944 from the Early Jurassic of China, and its relevance to the early evolution of Sauropoda (Dinosauria)
© 2016 McPhee et al.
This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ) and either DOI or URL of the article must be cited. The attached file is the published version of the article
Global similarity with local differences in linkage disequilibrium between the Dutch and HapMap–CEU populations
The HapMap project has facilitated the selection of tagging single nucleotide polymorphisms (tagSNPs) for genome-wide association studies (GWAS) under the assumption that linkage disequilibrium (LD) in the HapMap populations is similar to the populations under investigation. Earlier reports support this assumption, although in most of these studies only a few loci were evaluated. We compared pair-wise LD and LD block structure across autosomes between the Dutch population and the CEU-HapMap reference panel. The impact of sampling distribution on the estimation of LD blocks was studied by bootstrapping. A high Pearson correlation (genome-wide; 0.93) between pair-wise
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