102 research outputs found
Evaluating two methods for Treebank grammar compaction
Treebanks, such as the Penn Treebank, provide a basis for the automatic creation of broad coverage grammars. In the simplest case, rules can simply be ‘read off’ the parse-annotations of the corpus, producing either a simple or probabilistic context-free grammar. Such grammars, however, can be very large, presenting problems for the subsequent computational costs of parsing under the grammar.
In this paper, we explore ways by which a treebank grammar can be reduced in size or ‘compacted’, which involve the use of two kinds of technique: (i) thresholding of rules by their number of occurrences; and (ii) a method of rule-parsing, which has both probabilistic and non-probabilistic variants. Our results show that by a combined use of these two techniques, a probabilistic context-free grammar can be reduced in size by 62% without any loss in parsing performance, and by 71% to give a gain in recall, but some loss in precision
Changes of some blood indices and myocardial electrolyte content during hypokinesia
Using special hypokinetic cages, the volume changes of circulating blood, its hematocrit and protein content, volume ratios between extra- and intracellular liquids in the body, as well as electrolyte content in the blood and myocardium during hypokinesia were investigated experimentally in rabbits
Mechanisms of water-salt metabolism disturbances in dogs subjected to six month hypokinesia
Water-salt metabolism in dogs during prolonged restricted motor activity (hypokinesia) was investigated. It was found that hydration occurred and fluid was redistributed between the extra- and intra-cellular sectors. Also, electrolyte excretion rose, and magnetism and calcium metabolism changed significantly. It is concluded that the forces caused by muscle strain proper (which was decreased under conditions of hypokinesia) influence the state of bone metabolism
Functional Characterization of Lamina X Neurons in ex-Vivo Spinal Cord Preparation
Functional properties of lamina X neurons in the spinal cord remain unknown despite
the established role of this area for somatosensory integration, visceral nociception,
autonomic regulation and motoneuron output modulation. Investigations of neuronal
functioning in the lamina X have been hampered by technical challenges. Here we
introduce an ex-vivo spinal cord preparation with both dorsal and ventral roots still
attached for functional studies of the lamina X neurons and their connectivity using an
oblique LED illumination for resolved visualization of lamina X neurons in a thick tissue.
With the elaborated approach, we demonstrate electrophysiological characteristics
of lamina X neurons by their membrane properties, firing pattern discharge and
fiber innervation (either afferent or efferent). The tissue preparation has been also
probed using Ca2+ imaging with fluorescent Ca2+ dyes (membrane-impermeable or
-permeable) to demonstrate the depolarization-induced changes in intracellular calcium
concentration in lamina X neurons. Finally, we performed visualization of subpopulations
of lamina X neurons stained by retrograde labeling with aminostilbamidine dye to
identify sympathetic preganglionic and projection neurons in the lamina X. Thus, the
elaborated approach provides a reliable tool for investigation of functional properties
and connectivity in specific neuronal subpopulations, boosting research of lamina X of
the spinal cord
Distinct mechanisms of signal processing by lamina I spino-parabrachial neurons
Lamina I spino-parabrachial neurons (SPNs) receive peripheral nociceptive input, process it and transmit to the supraspinal centres. Although responses of SPNs to cutaneous receptive field stimulations have been intensively studied, the mechanisms of signal processing in these neurons are poorly understood. Therefore, we used an ex-vivo spinal cord preparation to examine synaptic and cellular mechanisms determining specific input-output characteristics of the neurons. The vast majority of the SPNs received a few direct nociceptive C-fiber inputs and generated one spike in response to saturating afferent stimulation, thus functioning as simple transducers of painful stimulus. However, 69% of afferent stimulation-induced action potentials in the entire SPN population originated from a small fraction (19%) of high-output neurons. These neurons received a larger number of direct Ad- and C-fiber inputs, generated intrinsic bursts and efficiently integrated a local network activity via NMDA-receptor-dependent mechanisms. The high-output SPNs amplified and integrated the nociceptive input gradually encoding its intensity into the number of generated spikes. Thus, different mechanisms of signal processing allow lamina I SPNs to play distinct roles in nociception.The authors thank Mr. Andrew Dromaretsky for the technical assistance. P.B. was supported by the National Academy of Sciences of Ukraine (NASU), grant NASU # 0116U004470, grant NASU#67/15-Н. N.V. was supported by the NASU Biotechnology and NASU-KNU grants; NIH 1R01NS113189-01. B.V.S. was supported by the FEDER funds through the COMPETE 2020 (POCI), Portugal 2020, and by the FCT project PTDC/NEU-NMC/1259/2014 (POCI-01-0145-FEDER-016588
Methods of labor economy increasing in educational organization
The urgency of problem under investigation due to fact that increasing demand of the information technology infrastructure development in current conditions of educational institutions functioning, including formation of the information-educational environment point of view. Offered organizational and economic model of constructing processes for software development is based on agile project management, regarded as an object-oriented tool for optimizing labor economics. The purpose of article is in model for labor economy processes optimization as a part of software development based on agile project management methodology in departments associated with development of information technologies in educational organization. The leading method to the problem study is in measurement of labor economics key indicators, including specific metrics of technical expert’s human capital growth. As an experimental base of research are considered educational organizations, at different times, using classical approach for software development and agile project management. The article presents research results of educational organizations departments engaged in project activities for development of information technologies, which are in the development of software products using classical approach for software development and agile project management. Article submissions may be useful to create a culture for constructing labor economics and human capital system based on sustainable growth in departments of educational institutions working in the field of information technology. © 2016 Dorozhkin et al
Effective low-energy theory for correlated carbon nanotubes
The low-energy theory for single-wall carbon nanotubes including Coulomb
interactions is derived and analyzed. It describes two fermion chains without
interchain hopping but coupled in a specific way by the interaction. The
strong-coupling properties are studied by bosonization, and consequences for
experiments on single armchair nanotubes are discussed.Comment: 5 pages REVTeX, includes one figur
Predicting a Gapless Spin-1 Neutral Collective Mode branch for Graphite
Using the standard tight binding model of 2d graphite with short range
electron repulsion, we find a gapless spin-1, neutral collective mode branch
{\em below the particle-hole continuum} with energy vanishing linearly with
momenta at the and points in the BZ. This spin-1 mode has a wide
energy dispersion, 0 to and is not Landau damped. The `Dirac cone
spectrum' of electrons at the chemical potential of graphite generates our
collective mode; so we call this `spin-1 zero sound' of the `Dirac sea'.
Epithermal neutron scattering experiments, where graphite single crystals are
often used as analyzers (an opportunity for `self-analysis'!), and spin
polarized electron energy loss spectroscopy (SPEELS) can be used to confirm and
study our collective mode.Comment: 4 pages of LaTex file, 3 eps figure file
Quantum spin field effect transistor
We propose, theoretically, a new type of quantum field effect transistor that
operates purely on the flow of spin current in the absence of charge current.
This spin field effect transistor (SFET) is constructed without any magnetic
material, but with the help of spin flip mechanism provided by a rotating
external magnetic field of uniform strength. The SFET generates a constant
instantaneous spin current that is sensitively controllable by a gate voltage
as well as by the frequency and strength of the rotating field. The
characteristics of a Carbon nanotube based SFET is provided as an example
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