3,470 research outputs found
Surface EMG-Based Inter-Session/Inter-Subject Gesture Recognition by Leveraging Lightweight All-ConvNet and Transfer Learning
Gesture recognition using low-resolution instantaneous HD-sEMG images opens
up new avenues for the development of more fluid and natural muscle-computer
interfaces. However, the data variability between inter-session and
inter-subject scenarios presents a great challenge. The existing approaches
employed very large and complex deep ConvNet or 2SRNN-based domain adaptation
methods to approximate the distribution shift caused by these inter-session and
inter-subject data variability. Hence, these methods also require learning over
millions of training parameters and a large pre-trained and target domain
dataset in both the pre-training and adaptation stages. As a result, it makes
high-end resource-bounded and computationally very expensive for deployment in
real-time applications. To overcome this problem, we propose a lightweight
All-ConvNet+TL model that leverages lightweight All-ConvNet and transfer
learning (TL) for the enhancement of inter-session and inter-subject gesture
recognition performance. The All-ConvNet+TL model consists solely of
convolutional layers, a simple yet efficient framework for learning invariant
and discriminative representations to address the distribution shifts caused by
inter-session and inter-subject data variability. Experiments on four datasets
demonstrate that our proposed methods outperform the most complex existing
approaches by a large margin and achieve state-of-the-art results on
inter-session and inter-subject scenarios and perform on par or competitively
on intra-session gesture recognition. These performance gaps increase even more
when a tiny amount (e.g., a single trial) of data is available on the target
domain for adaptation. These outstanding experimental results provide evidence
that the current state-of-the-art models may be overparameterized for
sEMG-based inter-session and inter-subject gesture recognition tasks
Evaluation of the Project P.A.T.H.S. in Mainland China: Findings Based on Student Diaries
Objectives: Based on 859 student diaries, the present study evaluated a positive youth development program entitled “Tin Ka Ping (TKP) Positive Adolescent Training through Holistic Social programs (P.A.T.H.S.) ” project implemented in mainland China during the 2015–2016 academic year. Method: To understand the perceived effectiveness of the students, the study analyzed quantitative as well as qualitative data derived from the student diaries. Results: The students held very positive views toward the program and the implementers. The narratives of the students also showed that they perceived improvement in the intrapersonal, interpersonal, familial, and societal domains after joining the program. Conclusion: In conjunction with the subjective outcome evaluation findings, the present findings suggest that the “TKP P.A.T.H.S.” project is able to promote holistic development of secondary school students in mainland China
Wave-induced loss of ultra-relativistic electrons in the Van Allen radiation belts.
The dipole configuration of the Earth's magnetic field allows for the trapping of highly energetic particles, which form the radiation belts. Although significant advances have been made in understanding the acceleration mechanisms in the radiation belts, the loss processes remain poorly understood. Unique observations on 17 January 2013 provide detailed information throughout the belts on the energy spectrum and pitch angle (angle between the velocity of a particle and the magnetic field) distribution of electrons up to ultra-relativistic energies. Here we show that although relativistic electrons are enhanced, ultra-relativistic electrons become depleted and distributions of particles show very clear telltale signatures of electromagnetic ion cyclotron wave-induced loss. Comparisons between observations and modelling of the evolution of the electron flux and pitch angle show that electromagnetic ion cyclotron waves provide the dominant loss mechanism at ultra-relativistic energies and produce a profound dropout of the ultra-relativistic radiation belt fluxes
Spin and Spin-Wave Dynamics in Josephson Junctions
We extend the Keldysh formulation to quantum spin systems and derive exact
equations of motion. This allows us to explore the dynamics of single spins and
of ferromagnets when these are inserted between superconducting leads. Several
new effects are reported. Chief amongst these are nutations of single S=1/2
spins in Josephson junctions. These nutations are triggered by the
superconducting pairing correlations in the leads. Similarly, we find that on
rather universal grounds, magnets display unconventional spin wave dynamics
when placed in Josephson junctions. These lead to modifications in the
tunneling current.Comment: (14 pages, 5 figures
Polarization instabilities in a two-photon laser
We describe the operating characteristics of a new type of quantum oscillator
that is based on a two-photon stimulated emission process. This two-photon
laser consists of spin-polarized and laser-driven K atoms placed in a
high-finesse transverse-mode-degenerate optical resonator, and produces a beam
with a power of 0.2 W at a wavelength of 770 nm. We observe
complex dynamical instabilities of the state of polarization of the two-photon
laser, which are made possible by the atomic Zeeman degeneracy. We conjecture
that the laser could emit polarization-entangled twin beams if this degeneracy
is lifted.Comment: Accepted by Physical Review Letters. REVTeX 4 pages, 4 EPS figure
Antithrombin attenuates myocardial dysfunction and reverses systemic fluid accumulation following burn and smoke inhalation injury: a randomized, controlled, experimental study
Introduction: We hypothesized that maintaining physiological plasma levels of antithrombin attenuates myocardial dysfunction and inflammation as well as vascular leakage associated with burn and smoke inhalation injury. Therefore, the present prospective, randomized experiment was conducted using an established ovine model. Methods: Following 40% of total body surface area, third degree flame burn and 4 × 12 breaths of cold cotton smoke, chronically instrumented sheep were randomly assigned to receive an intravenous infusion of 6 IU/kg/h recombinant human antithrombin (rhAT) or normal saline (control group; n = 6 each). In addition, six sheep were designated as sham animals (not injured, continuous infusion of vehicle). During the 48 h study period the animals were awake, mechanically ventilated and fluid resuscitated according to standard formulas. Results: Compared to the sham group, myocardial contractility was severely impaired in control animals, as suggested by lower stroke volume and left ventricular stroke work indexes. As a compensatory mechanism, heart rate increased, thereby increasing myocardial oxygen consumption. In parallel, myocardial inflammation was induced via nitric oxide production, neutrophil accumulation (myeloperoxidase activity) and activation of the p38-mitogen-activated protein kinase pathway resulting in cytokine release (tumor necrosis factor-alpha, interleukin-6) in control vs. sham animals. rhAT-treatment significantly attenuated these inflammatory changes leading to a myocardial contractility and myocardial oxygen consumption comparable to sham animals. In control animals, systemic fluid accumulation progressively increased over time resulting in a cumulative positive fluid balance of about 4,000 ml at the end of the study period. Contrarily, in rhAT-treated animals there was only an initial fluid accumulation until 24 h that was reversed back to the level of sham animals during the second day. Conclusions: Based on these findings, the supplementation of rhAT may represent a valuable therapeutic approach for cardiovascular dysfunction and inflammation after burn and smoke inhalation injury.<br
Quantitative Sequencing for the Determination of Kdr-type Resistance Allele (V419L,L925I, I936F) Frequencies in Common Bed Bug, Cimex lectularius L., (Hemiptera: Cimicidae) Populations Collected from Israel
Human bed bug infestations have dramatically increased worldwide since the mid-1990s. A similar phenomenon was also observed in Israel since 2005, when infestations were reported from all over the country. Two single nucleotide polymorphisms (V419L and L925I) in the bed bug voltage sensitive sodium channel confer kdr-type resistance to pyrethroids. Using quantitative sequencing (QS), the resistance allele frequencies of Israeli bed bug populations from across the country were determined. Genomic DNA was extracted from samples of 12 populations of bed bugs collected from Israel and DNA fragments containing the V419L or L925I and I936F mutations sites were PCR amplified. The PCR products were analyzed by QS and the nucleotide signal ratios calculated and used to predict the resistance allele frequencies of the unknown populations. Results of the genetic analysis show that resistant nucleotide signals are highly correlated to resistance allele frequencies for both mutations. Ten of the 12 tested populations had 100% of the L925I mutation and 0% of the V419L mutation. One population was heterogeneous for the L925I mutation and had 0% of the V419L mutation and another population was heterozygous for the V419L mutation and had 100% of the L925I mutation. I936F occurred only at low levels. These results indicate that bed bugs in Israel are genetically resistant to pyrethroids. Thus, pyrethroids should only be used for bed bug management with caution using effective application and careful monitoring procedures. Additionally, new and novel-acting insecticides and non-chemical means of controlling bed bugs should be explored
Creating, moving and merging Dirac points with a Fermi gas in a tunable honeycomb lattice
Dirac points lie at the heart of many fascinating phenomena in condensed
matter physics, from massless electrons in graphene to the emergence of
conducting edge states in topological insulators [1, 2]. At a Dirac point, two
energy bands intersect linearly and the particles behave as relativistic Dirac
fermions. In solids, the rigid structure of the material sets the mass and
velocity of the particles, as well as their interactions. A different, highly
flexible approach is to create model systems using fermionic atoms trapped in
the periodic potential of interfering laser beams, a method which so far has
only been applied to explore simple lattice structures [3, 4]. Here we report
on the creation of Dirac points with adjustable properties in a tunable
honeycomb optical lattice. Using momentum-resolved interband transitions, we
observe a minimum band gap inside the Brillouin zone at the position of the
Dirac points. We exploit the unique tunability of our lattice potential to
adjust the effective mass of the Dirac fermions by breaking inversion symmetry.
Moreover, changing the lattice anisotropy allows us to move the position of the
Dirac points inside the Brillouin zone. When increasing the anisotropy beyond a
critical limit, the two Dirac points merge and annihilate each other - a
situation which has recently attracted considerable theoretical interest [5-9],
but seems extremely challenging to observe in solids [10]. We map out this
topological transition in lattice parameter space and find excellent agreement
with ab initio calculations. Our results not only pave the way to model
materials where the topology of the band structure plays a crucial role, but
also provide an avenue to explore many-body phases resulting from the interplay
of complex lattice geometries with interactions [11, 12]
A biophysical model of cell adhesion mediated by immunoadhesin drugs and antibodies
A promising direction in drug development is to exploit the ability of
natural killer cells to kill antibody-labeled target cells. Monoclonal
antibodies and drugs designed to elicit this effect typically bind cell-surface
epitopes that are overexpressed on target cells but also present on other
cells. Thus it is important to understand adhesion of cells by antibodies and
similar molecules. We present an equilibrium model of such adhesion,
incorporating heterogeneity in target cell epitope density and epitope
immobility. We compare with experiments on the adhesion of Jurkat T cells to
bilayers containing the relevant natural killer cell receptor, with adhesion
mediated by the drug alefacept. We show that a model in which all target cell
epitopes are mobile and available is inconsistent with the data, suggesting
that more complex mechanisms are at work. We hypothesize that the immobile
epitope fraction may change with cell adhesion, and we find that such a model
is more consistent with the data. We also quantitatively describe the parameter
space in which binding occurs. Our results point toward mechanisms relating
epitope immobility to cell adhesion and offer insight into the activity of an
important class of drugs.Comment: 13 pages, 5 figure
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