1,386 research outputs found
Deep Convolutional Neural Networks for Interpretable Analysis of EEG Sleep Stage Scoring
Sleep studies are important for diagnosing sleep disorders such as insomnia,
narcolepsy or sleep apnea. They rely on manual scoring of sleep stages from raw
polisomnography signals, which is a tedious visual task requiring the workload
of highly trained professionals. Consequently, research efforts to purse for an
automatic stage scoring based on machine learning techniques have been carried
out over the last years. In this work, we resort to multitaper spectral
analysis to create visually interpretable images of sleep patterns from EEG
signals as inputs to a deep convolutional network trained to solve visual
recognition tasks. As a working example of transfer learning, a system able to
accurately classify sleep stages in new unseen patients is presented.
Evaluations in a widely-used publicly available dataset favourably compare to
state-of-the-art results, while providing a framework for visual interpretation
of outcomes.Comment: 8 pages, 1 figure, 2 tables, IEEE 2017 International Workshop on
Machine Learning for Signal Processin
Orientation-dependent ionization yields from strong-field ionization of fixed-in-space linear and asymmetric top molecules
The yield of strong-field ionization, by a linearly polarized probe pulse, is
studied experimentally and theoretically, as a function of the relative
orientation between the laser field and the molecule. Experimentally, carbonyl
sulfide, benzonitrile and naphthalene molecules are aligned in one or three
dimensions before being singly ionized by a 30 fs laser pulse centered at 800
nm. Theoretically, we address the behaviour of these three molecules. We
consider the degree of alignment and orientation and model the angular
dependence of the total ionization yield by molecular tunneling theory
accounting for the Stark shift of the energy level of the ionizing orbital. For
naphthalene and benzonitrile the orientational dependence of the ionization
yield agrees well with the calculated results, in particular the observation
that ionization is maximized when the probe laser is polarized along the most
polarizable axis. For OCS the observation of maximum ionization yield when the
probe is perpendicular to the internuclear axis contrasts the theoretical
results.Comment: 14 pages, 4 figure
Controls on the rheological properties of peridotite at a palaeosubduction interface: A transect across the base of the Oman-UAE ophiolite
Studies of experimentally deformed rocks and small-scale natural shear zones have
demonstrated that volumetrically minor phases can control strain localisation by limiting grain growth
and promoting grain-size sensitive deformation mechanisms. These small-scale studies are often used
to infer a critical role for minor phases in the development of plate boundaries. However, the role of
minor phases in strain localisation at an actual plate boundary remains to be tested by direct
observation. In order to test the hypothesis that minor phases control strain localisation at plate
boundaries, we conducted microstructural analyses of peridotite samples collected along a ~1 km
transect across the base of the Oman-United Arab Emirates (UAE) ophiolite. The base of the ophiolite
is marked by the Semail thrust, which represents the now exhumed contact between subducted
oceanic crust and the overlying mantle wedge. As such, the base of the ophiolite provides the
opportunity to directly examine a former plate boundary.
Our results demonstrate that the mean olivine grain size is inversely proportional to the
abundance of minor phases (primarily orthopyroxene, as well as clinopyroxene, hornblende, and
spinel), consistent with suppression of grain growth by grain-boundary pinning. Our results also
reveal that mean olivine grain size is proportional to CPO strength (both of which generally decrease
towards the metamorphic sole), suggesting that the fraction of strain produced by different
deformation mechanisms varied spatially. Experimentally-derived flow laws indicate that under the
inferred deformation conditions, the viscosity of olivine was grain-size sensitive. As such, grain size,
and thereby the abundance of minor phases, influenced viscosity during subduction-related
deformation along the base of the mantle wedge.
We calculate an order of magnitude decrease in the viscosity of olivine towards the base of
the ophiolite, which suggests strain was localized near the subduction interface. Our data indicate that
this rheological weakening was primarily the result of more abundant minor phases near the base of
the ophiolite. Our interpretations are consistent with those of previous studies on experimentally
deformed rocks and smaller-scale natural shear zones that indicate minor phases can exert the primary
control on strain localisation. However, our study demonstrates for the first time that minor phases can
control strain localisation at the scales relevant to a major plate boundar
A novel suture method to place and adjust peripheral nerve catheters
We have developed a peripheral nerve catheter, attached to a needle, which works like an adjustable suture. We used inâplane ultrasound guidance to place 45 catheters close to the femoral, saphenous, sciatic and distal tibial nerves in cadaver legs. We displaced catheters after their initial placement and then attempted to return them to their original positions. We used ultrasound to evaluate the initial and secondary catheter placements and the spread of injectate around the nerves. In 10 cases, we confirmed catheter position by magnetic resonance imaging. We judged 43/45 initial placements successful and 42/43 secondary placements successful by ultrasound, confirmed in 10/10 cases by magnetic resonance imaging
Measuring Corporate Reputation using Sentiment Analysis
In recent years, new digital media have become important for social networking and content sharing. Due to their large diffusion, social media platforms have also both increased the strategic importance of managing corporate reputation and rendered this more difficult. Companies are increasingly apprehensive about information and opinions that can spread through online communities rapidly without any control. While social media platforms increase the power of stakeholders, they also represent a large-scale source of information about feelings, opinions and sentiments of people that allow us to measure and monitor reputation through the analysis of user generated content in real-time. In this paper, we show how social media content can be used to measure the online reputation of a company. Furthermore, we present an open platform that uses a sentiment analysis algorithm on twitter traffic to monitor the real time evolution of company reputation
- âŚ