259 research outputs found
Tongue interface based on surface EMG signals of suprahyoid muscles
The research described herein was undertaken to develop and test a novel tongue interface based on classification of tongue motions from the surface electromyography (EMG) signals of the suprahyoid muscles detected at the underside of the jaw. The EMG signals are measured via 22 active surface electrodes mounted onto a special flexible boomerang-shaped base. Because of the sensor’s shape and flexibility, it can adapt to the underjaw skin contour. Tongue motion classification was achieved using a support vector machine (SVM) algorithm for pattern recognition where the root mean square (RMS) features and cepstrum coefficients (CC) features of the EMG signals were analyzed. The effectiveness of the approach was verified with a test for the classification of six tongue motions conducted with a group of five healthy adult volunteer subjects who had normal motor tongue functions. Results showed that the system classified all six tongue motions with high accuracy of 95.1 ± 1.9 %. The proposed method for control of assistive devices was evaluated using a test in which a computer simulation model of an electric wheelchair was controlled using six tongue motions. This interface system, which weighs only 13.6 g and which has a simple appearance, requires no installation of any sensor into the mouth cavity. Therefore, it does not hinder user activities such as swallowing, chewing, or talking. The number of tongue motions is sufficient for the control of most assistive devices
Monte Carlo Simulation of Sinusoidally Modulated Superlattice Growth
The fabrication of ZnSe/ZnTe superlattices grown by the process of rotating
the substrate in the presence of an inhomogeneous flux distribution instead of
successively closing and opening of source shutters is studied via Monte Carlo
simulations. It is found that the concentration of each compound is
sinusoidally modulated along the growth direction, caused by the uneven arrival
of Se and Te atoms at a given point of the sample, and by the variation of the
Te/Se ratio at that point due to the rotation of the substrate. In this way we
obtain a ZnSeTe alloy in which the composition varies
sinusoidally along the growth direction. The period of the modulation is
directly controlled by the rate of the substrate rotation. The amplitude of the
compositional modulation is monotonous for small angular velocities of the
substrate rotation, but is itself modulated for large angular velocities. The
average amplitude of the modulation pattern decreases as the angular velocity
of substrate rotation increases and the measurement position approaches the
center of rotation. The simulation results are in good agreement with
previously published experimental measurements on superlattices fabricated in
this manner
Nogo-B regulates endothelial sphingolipid homeostasis to control vascular function and blood pressure.
Endothelial dysfunction is a critical factor in many cardiovascular diseases, including hypertension. Although lipid signaling has been implicated in endothelial dysfunction and cardiovascular disease, specific molecular mechanisms are poorly understood. Here we report that Nogo-B, a membrane protein of the endoplasmic reticulum, regulates endothelial sphingolipid biosynthesis with direct effects on vascular function and blood pressure. Nogo-B inhibits serine palmitoyltransferase, the rate-limiting enzyme of the de novo sphingolipid biosynthetic pathway, thereby controlling production of endothelial sphingosine 1-phosphate and autocrine, G protein-coupled receptor-dependent signaling by this metabolite. Mice lacking Nogo-B either systemically or specifically in endothelial cells are hypotensive, resistant to angiotensin II-induced hypertension and have preserved endothelial function and nitric oxide release. In mice that lack Nogo-B, pharmacological inhibition of serine palmitoyltransferase with myriocin reinstates endothelial dysfunction and angiotensin II-induced hypertension. Our study identifies Nogo-B as a key inhibitor of local sphingolipid synthesis and shows that autocrine sphingolipid signaling within the endothelium is critical for vascular function and blood pressure homeostasis
Nucleon-Nucleon Interaction: A Typical/Concise Review
Nearly a recent century of work is divided to Nucleon-Nucleon (NN)
interaction issue. We review some overall perspectives of NN interaction with a
brief discussion about deuteron, general structure and symmetries of NN
Lagrangian as well as equations of motion and solutions. Meanwhile, the main NN
interaction models, as frameworks to build NN potentials, are reviewed
concisely. We try to include and study almost all well-known potentials in a
similar way, discuss more on various commonly used plain forms for two-nucleon
interaction with an emphasis on the phenomenological and meson-exchange
potentials as well as the constituent-quark potentials and new ones based on
chiral effective field theory and working in coordinate-space mostly. The
potentials are constructed in a way that fit NN scattering data, phase shifts,
and are also compared in this way usually. An extra goal of this study is to
start comparing various potentials forms in a unified manner. So, we also
comment on the advantages and disadvantages of the models and potentials partly
with reference to some relevant works and probable future studies.Comment: 85 pages, 5 figures, than the previous v3 edition, minor changes, and
typos fixe
Cortical phase transitions, non-equilibrium thermodynamics and the time-dependent Ginzburg-Landau equation
The formation of amplitude modulated and phase modulated assemblies of
neurons is observed in the brain functional activity. The study of the
formation of such structures requires that the analysis has to be organized in
hierarchical levels, microscopic, mesoscopic, macroscopic, each with its
characteristic space-time scales and the various forms of energy, electric,
chemical, thermal produced and used by the brain. In this paper, we discuss the
microscopic dynamics underlying the mesoscopic and the macroscopic levels and
focus our attention on the thermodynamics of the non-equilibrium phase
transitions. We obtain the time-dependent Ginzburg-Landau equation for the
non-stationary regime and consider the formation of topologically non-trivial
structures such as the vortex solution. The power laws observed in functional
activities of the brain is also discussed and related to coherent states
characterizing the many-body dissipative model of brain.Comment: 19 pages, 4 figures, research pape
HEX expression and localization in normal mammary gland and breast carcinoma
BACKGROUND: The homeobox gene HEX is expressed in several cell types during different phases of animal development. It encodes for a protein localized in both the nucleus and the cytoplasm. During early mouse development, HEX is expressed in the primitive endoderm of blastocyst. Later, HEX is expressed in developing thyroid, liver, lung, as well as in haematopoietic progenitors and endothelial cells. Absence of nuclear expression has been observed during neoplastic transformation of the thyroid follicular cells. Aim of the present study was to evaluate the localization and the function of the protein HEX in normal and tumoral breast tissues and in breast cancer cell lines. METHODS: HEX expression and nuclear localization were investigated by immunohistochemistry in normal and cancerous breast tissue, as well as in breast cancer cell lines. HEX mRNA levels were evaluated by real-time PCR. Effects of HEX expression on Sodium Iodide Symporter (NIS) gene promoter activity was investigated by HeLa cell transfection. RESULTS: In normal breast HEX was detected both in the nucleus and in the cytoplasm. In both ductal and lobular breast carcinomas, a great reduction of nuclear HEX was observed. In several cells from normal breast tissue as well as in MCF-7 and T47D cell line, HEX was observed in the nucleolus. MCF-7 treatment with all-trans retinoic acid enhanced HEX expression and induced a diffuse nuclear localization. Enhanced HEX expression and diffuse nuclear localization were also obtained when MCF-7 cells were treated with inhibitors of histone deacetylases such as sodium butyrate and trichostatin A. With respect to normal non-lactating breast, the amount of nuclear HEX was greatly increased in lactating tissue. Transfection experiments demonstrated that HEX is able to up-regulate the activity of NIS promoter. CONCLUSION: Our data indicate that localization of HEX is regulated in epithelial breast cells. Since modification of localization occurs during lactation and tumorigenesis, we suggest that HEX may play a role in differentiation of the epithelial breast cell
State dependence of climatic instability over the past 720,000 years from Antarctic ice cores and climate modeling
Climatic variabilities on millennial and longer time scales with a bipolar seesaw pattern have been documented in paleoclimatic records, but their frequencies, relationships with mean climatic state, and mechanisms remain unclear. Understanding the processes and sensitivities that underlie these changes will underpin better understanding of the climate system and projections of its future change. We investigate the long-term characteristics of climatic variability using a new ice-core record from Dome Fuji, East Antarctica, combined with an existing long record from the Dome C ice core. Antarctic warming events over the past 720,000 years are most frequent when the Antarctic temperature is slightly below average on orbital time scales, equivalent to an intermediate climate during glacial periods, whereas interglacial and fully glaciated climates are unfavourable for a millennial-scale bipolar seesaw. Numerical experiments using a fully coupled atmosphere-ocean general circulation model with freshwater hosing in the northern North Atlantic showed that climate becomes most unstable in intermediate glacial conditions associated with large changes in sea ice and the Atlantic Meridional Overturning Circulation. Model sensitivity experiments suggest that the prerequisite for the most frequent climate instability with bipolar seesaw pattern during the late Pleistocene era is associated with reduced atmospheric CO2 concentration via global cooling and sea ice formation in the North Atlantic, in addition to extended Northern Hemisphere ice sheets
Practical recipes for the model order reduction, dynamical simulation, and compressive sampling of large-scale open quantum systems
This article presents numerical recipes for simulating high-temperature and
non-equilibrium quantum spin systems that are continuously measured and
controlled. The notion of a spin system is broadly conceived, in order to
encompass macroscopic test masses as the limiting case of large-j spins. The
simulation technique has three stages: first the deliberate introduction of
noise into the simulation, then the conversion of that noise into an equivalent
continuous measurement and control process, and finally, projection of the
trajectory onto a state-space manifold having reduced dimensionality and
possessing a Kahler potential of multi-linear form. The resulting simulation
formalism is used to construct a positive P-representation for the thermal
density matrix. Single-spin detection by magnetic resonance force microscopy
(MRFM) is simulated, and the data statistics are shown to be those of a random
telegraph signal with additive white noise. Larger-scale spin-dust models are
simulated, having no spatial symmetry and no spatial ordering; the
high-fidelity projection of numerically computed quantum trajectories onto
low-dimensionality Kahler state-space manifolds is demonstrated. The
reconstruction of quantum trajectories from sparse random projections is
demonstrated, the onset of Donoho-Stodden breakdown at the Candes-Tao sparsity
limit is observed, a deterministic construction for sampling matrices is given,
and methods for quantum state optimization by Dantzig selection are given.Comment: 104 pages, 13 figures, 2 table
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