1,600 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
Client Adaptation improves Federated Learning with Simulated Non-IID Clients
We present a federated learning approach for learning a client adaptable,
robust model when data is non-identically and non-independently distributed
(non-IID) across clients. By simulating heterogeneous clients, we show that
adding learned client-specific conditioning improves model performance, and the
approach is shown to work on balanced and imbalanced data set from both audio
and image domains. The client adaptation is implemented by a conditional gated
activation unit and is particularly beneficial when there are large differences
between the data distribution for each client, a common scenario in federated
learning.Comment: 11 pages, 11 figures. To appear at International Workshop on
Federated Learning for User Privacy and Data Confidentiality in Conjunction
with ICML 202
Classical Nucleation Theory of the One-Component Plasma
We investigate the crystallization rate of a one-component plasma (OCP) in
the context of classical nucleation theory. From our derivation of the free
energy of an arbitrary distribution of solid clusters embedded in a liquid
phase, we derive the steady-state nucleation rate of an OCP as a function of
the Coulomb coupling parameter. Our result for the rate is in accord with
recent molecular dynamics simulations, but it is greater than that of previous
analytical estimates by many orders of magnitude. Further molecular dynamics
simulations of the nucleation rate of a supercooled liquid OCP for several
values of the coupling parameter would clarify the physics of this process.Comment: 6 pages, 1 figure, accepted by PR
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
Life cycle modelling of environmental impacts of application of processed organic municipal solid waste on agricultural land (EASEWASTE)
A model capable of quantifying the potential environmental impacts of agricultural application of composted or anaerobically digested source-separated organic municipal solid waste (MSW) is presented. In addition to the direct impacts, the model accounts for savings by avoiding the production and use of commercial fertilizers. The model is part of a larger model, Environmental Assessment of Solid Waste Systems and Technology (EASEWASTE), developed as a decisionsupport model, focusing on assessment of alternative waste management options. The environmental impacts of the land application of processed organic waste are quantified by emission coefficients referring to the composition of the processed waste and related to specific crop rotation as well as soil type. The model contains several default parameters based on literature data, field experiments and modelling by the agro-ecosystem model, Daisy. All data can be modified by the user allowing application of the model to other situations. A case study including four scenarios was performed to illustrate the use of the model. One tonne of nitrogen in composted and anaerobically digested MSW was applied as fertilizer to loamy and sandy soil at a plant farm in western Denmark. Application of the processed organic waste mainly affected the environmental impact categories global warming (0.4â0.7 PE), acidification (â0.06 (saving)â1.6 PE), nutrient enrichment (â1.0 (saving)â3.1 PE), and toxicity. The main contributors to these categories were nitrous oxide formation (global warming), ammonia volatilization (acidification and nutrient enrichment), nitrate losses (nutrient enrichment and groundwater contamination), and heavy metal input to soil (toxicity potentials). The local agricultural conditions as well as the composition of the processed MSW showed large influence on the environmental impacts. A range of benefits, mainly related to improved soil quality from long-term application of the processed organic waste, could not be generally quantified with respect to the chosen life cycle assessment impact categories and were therefore not included in the model. These effects should be considered in conjunction with the results of the life cycle assessment
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
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