5,262 research outputs found
Carbon nanotube quantum dots on hexagonal boron nitride
We report the fabrication details and low-temperature characteristics of the
first carbon nanotube (CNT) quantum dots on flakes of hexagonal boron nitride
(hBN) as substrate. We demonstrate that CNTs can be grown on hBN by standard
chemical vapor deposition and that standard scanning electron microscopy
imaging and lithography can be employed to fabricate nanoelectronic structures
when using optimized parameters. This proof of concept paves the way to more
complex devices on hBN, with more predictable and reproducible characteristics
and electronic stability.Comment: 4 pages, 4 figure
Neural correlates of âpessimistic' attitude in depression
Background Preparing for potentially threatening events in the future is essential for survival. Anticipating the future to be unpleasant is also a cognitive key feature of depression. We hypothesized that âpessimism'-related emotion processing would characterize brain activity in major depression. Method During functional magnetic resonance imaging, depressed patients and a healthy control group were cued to expect and then perceive pictures of known emotional valences - pleasant, unpleasant and neutral - and stimuli of unknown valence that could have been either pleasant or unpleasant. Brain activation associated with the âunknown' expectation was compared with the âknown' expectation conditions. Results While anticipating pictures of unknown valence, activation patterns in depressed patients within the medial and dorsolateral prefrontal areas, inferior frontal gyrus, insula and medial thalamus were similar to activations associated with expecting unpleasant pictures, but not with expecting positive pictures. The activity within a majority of these areas correlated with the depression scores. Differences between healthy and depressed persons were found particularly for medial and dorsolateral prefrontal and insular activations. Conclusions Brain activation in depression during expecting events of unknown emotional valence was comparable with activation while expecting certainly negative, but not positive events. This neurobiological finding is consistent with cognitive models supposing that depressed patients develop a âpessimistic' attitude towards events with an unknown emotional meaning. Thereby, particularly the role of brain areas associated with the processing of cognitive and executive control and of the internal state is emphasized in contributing to major depressio
Deep Learning using K-space Based Data Augmentation for Automated Cardiac MR Motion Artefact Detection
Quality assessment of medical images is essential for complete automation of
image processing pipelines. For large population studies such as the UK
Biobank, artefacts such as those caused by heart motion are problematic and
manual identification is tedious and time-consuming. Therefore, there is an
urgent need for automatic image quality assessment techniques. In this paper,
we propose a method to automatically detect the presence of motion-related
artefacts in cardiac magnetic resonance (CMR) images. As this is a highly
imbalanced classification problem (due to the high number of good quality
images compared to the low number of images with motion artefacts), we propose
a novel k-space based training data augmentation approach in order to address
this problem. Our method is based on 3D spatio-temporal Convolutional Neural
Networks, and is able to detect 2D+time short axis images with motion artefacts
in less than 1ms. We test our algorithm on a subset of the UK Biobank dataset
consisting of 3465 CMR images and achieve not only high accuracy in detection
of motion artefacts, but also high precision and recall. We compare our
approach to a range of state-of-the-art quality assessment methods.Comment: Accepted for MICCAI2018 Conferenc
4216 Application of artificial neural networks for image analysis of organ culture preserved donor corneas: A pilot study
Gastrointestinal (GI) cancers account for 1.5 million deaths worldwide. Endoscopic Submucosal Dissection (ESD) is an advanced therapeutic endoscopy technique with superior clinical outcome due to the minimally invasive and en bloc removal of tumours. In the western world, ESD is seldom carried out, due to its complex and challenging nature. Various surgical systems are being developed to make this therapy accessible, however, these solutions have shown limited operational workspace, dexterity, or low force exertion capabilities. The current paper shows the ESD CYCLOPS system, a bimanual surgical robotic attachment that can be mounted at the end of any flexible endoscope. The system is able to achieve forces of up to 46N, and showed a mean error of 0.217mm during an elliptical tracing task. The workspace and instrument dexterity is shown by pre-clinical ex vivo trials, in which ESD is successfully performed by a GI surgeon. The system is currently undergoing pre-clinical in vivo validation
Ambiguity, multiple streams, and EU policy
The multiple streams framework draws insight from interactions between agency and institutions to explore the impact of context, time, and meaning on policy change and to assess the institutional and issue complexities permeating the European Union (EU) policy process. The authors specify the assumptions and structure of the framework and review studies that have adapted it to reflect more fully EU decision-making processes. The nature of policy entrepreneurship and policy windows are assessed to identify areas of improvement. Finally, the authors sketch out a research agenda that refines the logic of political manipulation which permeates the lens and the institutional complexity which frames the EU policy process
A Real-Time Microwave Camera at 24 GHz (K-Band}
The objective is to design and build a real-time microwave imaging system (i.e., camera) Microwave imaging offers tremendous potential in many applications: a) Inspection of low-loss composites, radomes, etc.; b) Detection and evaluation of corrosion under paint; c) Security, contraband detection. Raster scanning is slow and requires bulky mechanical systems. A real-time and portable imaging system can be extremely useful for rapid nondestructive testing of large structures
Spacings of Quarkonium Levels with the Same Principal Quantum Number
The spacings between bound-state levels of the Schr\"odinger equation with
the same principal quantum number but orbital angular momenta
differing by unity are found to be nearly equal for a wide range of power
potentials , with . Semiclassical approximations are in accord with this behavior. The
result is applied to estimates of masses for quarkonium levels which have not
yet been observed, including the 2P states and the 1D
states.Comment: 20 pages, latex, 3 uuencoded figures submitted separately (process
using psfig.sty
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