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Sample records for magnetoencephalography multipolar modeling

  1. MEG (Magnetoencephalography) multipolar modeling of distributed sources using RAP-MUSIC (Recursively Applied and Projected Multiple Signal Characterization)

    Mosher, J. C. (John C.); Baillet, S. (Sylvain); Jerbi, K. (Karim); Leahy, R. M. (Richard M.)

    2001-01-01

    We describe the use of truncated multipolar expansions for producing dynamic images of cortical neural activation from measurements of the magnetoencephalogram. We use a signal-subspace method to find the locations of a set of multipolar sources, each of which represents a region of activity in the cerebral cortex. Our method builds up an estimate of the sources in a recursive manner, i.e. we first search for point current dipoles, then magnetic dipoles, and finally first order multipoles. The dynamic behavior of these sources is then computed using a linear fit to the spatiotemporal data. The final step in the procedure is to map each of the multipolar sources into an equivalent distributed source on the cortical surface. The method is illustrated through an application to epileptic interictal MEG data.

  2. Magnetoencephalography

    Schwartz, Erin Simon [Children' s Hospital of Philadelphia, Lurie Family Foundations MEG Imaging Center, Department of Radiology, Philadelphia, PA (United States); Children' s Hospital of Philadelphia, Department of Radiology, Philadelphia, PA (United States); Edgar, J.C.; Gaetz, William C.; Roberts, Timothy P.L. [Children' s Hospital of Philadelphia, Lurie Family Foundations MEG Imaging Center, Department of Radiology, Philadelphia, PA (United States)

    2010-01-15

    Although magnetoencephalography (MEG) may not be familiar to many pediatric radiologists, it is an increasingly available neuroimaging technique both for evaluating normal and abnormal intracranial neural activity and for functional mapping. By providing spatial, temporal, and time-frequency spectral information, MEG affords patients with epilepsy, intracranial neoplasia, and vascular malformations an opportunity for a sensitive and accurate non-invasive preoperative evaluation. This technique can optimize selection of surgical candidates as well as increase confidence in preoperative counseling and prognosis. Research applications that appear promising for near-future clinical translation include the evaluation of children with autism spectrum disorder, traumatic brain injury, and schizophrenia. (orig.)

  3. Magnetoencephalography

    Although magnetoencephalography (MEG) may not be familiar to many pediatric radiologists, it is an increasingly available neuroimaging technique both for evaluating normal and abnormal intracranial neural activity and for functional mapping. By providing spatial, temporal, and time-frequency spectral information, MEG affords patients with epilepsy, intracranial neoplasia, and vascular malformations an opportunity for a sensitive and accurate non-invasive preoperative evaluation. This technique can optimize selection of surgical candidates as well as increase confidence in preoperative counseling and prognosis. Research applications that appear promising for near-future clinical translation include the evaluation of children with autism spectrum disorder, traumatic brain injury, and schizophrenia. (orig.)

  4. Bremsstrahlung during $\\alpha$-decay: quantum multipolar model

    Maydanyuk, Sergei P

    2008-01-01

    In this paper the improved multipolar model of bremsstrahlung accompanied the $\\alpha$-decay is presented. The angular formalism of calculations of the matrix elements, being enough complicated component of the model, is stated in details. A new definition of the angular (differential) probability of the photon emission in the $\\alpha$-decay is proposed where direction of motion of the $\\alpha$-particle outside (with its tunneling inside barrier) is defined on the basis of angular distribution of its spacial wave function. In such approach, the model gives values of the angular probability of the photons emission in absolute scale, without its normalization on experimental data. Effectiveness of the proposed definition and accuracy of the spectra calculations of the bremsstrahlung spectra are analyzed in their comparison with experimental data for the $^{210}{\\rm Po}$, $^{214}{\\rm Po}$, $^{226}{\\rm Ra}$ and $^{244}{\\rm Cm}$ nuclei, and for some other nuclei predictions are performed (in absolute scale). With ...

  5. A wind-shell interaction model for multipolar planetary nebulae

    Steffen, W; Esquivel, A; Garcia-Segura, G; Garcia-Diaz, Ma T; Lopez, J A; Magnor, M

    2013-01-01

    We explore the formation of multipolar structures in planetary and pre-planetary nebulae from the interaction of a fast post-AGB wind with a highly inhomogeneous and filamentary shell structure assumed to form during the final phase of the high density wind. The simulations were performed with a new hydrodynamics code integrated in the interactive framework of the astrophysical modeling package SHAPE. In contrast to conventional astrophysical hydrodynamics software, the new code does not require any programming intervention by the user for setting up or controlling the code. Visualization and analysis of the simulation data has been done in SHAPE without external software. The key conclusion from the simulations is that secondary lobes in planetary nebulae, such as Hubble 5 and K3-17, can be formed through the interaction of a fast low-density wind with a complex high density environment, such as a filamentary circumstellar shell. The more complicated alternative explanation of intermittent collimated outflow...

  6. Error bounds in MEG (Magnetoencephalography) multipole localization

    Jerbi, K. (Karim); Mosher, J. C. (John C.); Baillet, S. (Sylvain); Leahy, R. M. (Richard M.)

    2001-01-01

    Magnetoencephalography (MEG) is a non-invasive method that enables the measurement of the magnetic field produced by neural current sources within the human brain. Unfortunately, MEG source estimation is a severely ill-posed inverse problem. The two major approaches used to tackle this problem are 'imaging' and 'model-based' methods. The first class of methods relies on a tessellation of the cortex, assigning an elemental current source to each area element and solving the linear inverse problem. Accurate tessellations lead to a highly underdetermined problem, and regularized linear methods lead to very smooth current distributions. An alternative approach widely used is a parametric representation of the neural source. Such model-based methods include the classic equivalent current dipole (ECD) and its multiple current dipole extension [1]. The definition of such models has been based on the assumption that the underlying sources are focal and small in number. An alternative approach reviewed in [4], [5] is to extend the parametric source representations within the model-based framework to allow for distributed sources. The multipolar expansion of the magnetic field about the centroid of a distributed source readily offers an elegant parametric model, which collapses to a dipole model in the limiting case and includes higher order terms in the case of a spatially extended source. While multipolar expansions have been applied to magnetocardiography (MCG) source modeling [2], their use in MEG has been restricted to simplified models [7]. The physiological interpretation of these higher-order components in non-intuitive, therefore limiting their application in this community (cf. [8]). In this study we investigate both the applicability of dipolar and multipolar models to cortical patches, and the accuracy with which we can locate these sources. We use a combination of Monte Carlo analyses and Cramer-Rao lower bounds (CRLBs), paralleling the work

  7. Practical and Simple Wireless Channel Models for Use in Multipolarized Antenna Systems

    KwangHyun Jeon

    2014-01-01

    Full Text Available The next-generation wireless systems are expected to support data rates of more than 100 Mbps in outdoor environments. In order to support such large payloads, a polarized antenna may be employed as one of the candidate technologies. Recently, the third generation partnership standards bodies (3GPP/3GPP2 have defined a cross-polarized channel model in SCM-E for MIMO systems; however, this model is quite complex since it considers a great many channel-related parameters. Furthermore, the SCM-E channel model combines the channel coefficients of all the polarization links into one complex output, making it impossible to exploit the MIMO spatial multiplexing or diversity gains in the case of employing polarized antenna at transmitter and receiver side. In this paper, we present practical and simple 2D and 3D multipolarized multipath channel models, which take into account both the cross-polarization discrimination (XPD and the Rician factor. After verifying the proposed channel models, the BER and PER performances and throughput using the EGC and MRC combining techniques are evaluated in multipolarized antenna systems.

  8. Libration driven multipolar instabilities

    Cébron, David; Herreman, Wietze

    2014-01-01

    We consider rotating flows in non-axisymmetric enclosures that are driven by libration, i.e. by a small periodic modulation of the rotation rate. Thanks to its simplicity, this model is relevant to various contexts, from industrial containers (with small oscillations of the rotation rate) to fluid layers of terrestial planets (with length-of-day variations). Assuming a multipolar $n$-fold boundary deformation, we first obtain the two-dimensional basic flow. We then perform a short-wavelength local stability analysis of the basic flow, showing that an instability may occur in three dimensions. We christen it the Libration Driven Multipolar Instability (LDMI). The growth rates of the LDMI are computed by a Floquet analysis in a systematic way, and compared to analytical expressions obtained by perturbation methods. We then focus on the simplest geometry allowing the LDMI, a librating deformed cylinder. To take into account viscous and confinement effects, we perform a global stability analysis, which shows that...

  9. Evaluation of the solid state dipole moment and pyroelectric coefficient of phosphangulene by multipolar modeling of X-ray structure factors

    Madsen, G.K.H.; Krebs, Frederik C; Lebech, B.;

    2000-01-01

    The electron density distribution of the molecular pyroelectric material phosphangulene has been studied by multipolar modeling of X-ray diffraction data. The "in-crystal" molecular dipole moment has been evaluated to 4.7 D corresponding to a 42% dipole moment enhancement compared with the dipole...

  10. Magnetoencephalography recording and analysis

    Jayabal Velmurugan

    2014-01-01

    Full Text Available Magnetoencephalography (MEG non-invasively measures the magnetic field generated due to the excitatory postsynaptic electrical activity of the apical dendritic pyramidal cells. Such a tiny magnetic field is measured with the help of the biomagnetometer sensors coupled with the Super Conducting Quantum Interference Device (SQUID inside the magnetically shielded room (MSR. The subjects are usually screened for the presence of ferromagnetic materials, and then the head position indicator coils, electroencephalography (EEG electrodes (if measured simultaneously, and fiducials are digitized using a 3D digitizer, which aids in movement correction and also in transferring the MEG data from the head coordinates to the device and voxel coordinates, thereby enabling more accurate co-registration and localization. MEG data pre-processing involves filtering the data for environmental and subject interferences, artefact identification, and rejection. Magnetic resonance Imaging (MRI is processed for correction and identifying fiducials. After choosing and computing for the appropriate head models (spherical or realistic; boundary/finite element model, the interictal/ictal epileptiform discharges are selected and modeled by an appropriate source modeling technique (clinically and commonly used - single equivalent current dipole - ECD model. The equivalent current dipole (ECD source localization of the modeled interictal epileptiform discharge (IED is considered physiologically valid or acceptable based on waveform morphology, isofield pattern, and dipole parameters (localization, dipole moment, confidence volume, goodness of fit. Thus, MEG source localization can aid clinicians in sublobar localization, lateralization, and grid placement, by evoking the irritative/seizure onset zone. It also accurately localizes the eloquent cortex-like visual, language areas. MEG also aids in diagnosing and delineating multiple novel findings in other neuropsychiatric

  11. Multipolar nonlinear nanophotonics

    Smirnova, Daria

    2016-01-01

    Nonlinear nanophotonics is a rapidly developing field with many useful applications for a design of nonlinear nanoantennas, light sources, nanolasers, sensors, and ultrafast miniature metadevices. A tight confinement of the local electromagnetic fields in resonant photonic nanostructures can boost nonlinear optical effects, thus offering versatile opportunities for subwavelength control of light. To achieve the desired functionalities, it is essential to gain flexible control over the near- and far-field properties of nanostructures. Thus, both modal and multipolar analyses are widely exploited for engineering nonlinear scattering from resonant nanoscale elements, in particular for enhancing the near-field interaction, tailoring the far-field multipolar interference, and optimization of the radiation directionality. Here, we review the recent advances in this recently emerged research field ranging from metallic structures exhibiting localized plasmonic resonances to hybrid metal-dielectric and all-dielectric...

  12. Detecting forest structure and biomass with C-band multipolarization radar - Physical model and field tests

    Westman, Walter E.; Paris, Jack F.

    1987-01-01

    The ability of C-band radar (4.75 GHz) to discriminate features of forest structure, including biomass, is tested using a truck-mounted scatterometer for field tests on a 1.5-3.0 m pygmy forest of cypress (Cupressus pygmaea) and pine (Pinus contorta ssp, Bolanderi) near Mendocino, CA. In all, 31 structural variables of the forest are quantified at seven sites. Also measured was the backscatter from a life-sized physical model of the pygmy forest, composed of nine wooden trees with 'leafy branches' of sponge-wrapped dowels. This model enabled independent testing of the effects of stem, branch, and leafy branch biomass, branch angle, and moisture content on radar backscatter. Field results suggested that surface area of leaves played a greater role in leaf scattering properties than leaf biomass per se. Tree leaf area index was strongly correlated with vertically polarized power backscatter (r = 0.94; P less than 0.01). Field results suggested that the scattering role of leaf water is enhanced as leaf surface area per unit leaf mass increases; i.e., as the moist scattering surfaces become more dispersed. Fog condensate caused a measurable rise in forest backscatter, both from surface and internal rises in water content. Tree branch mass per unit area was highly correlated with cross-polarized backscatter in the field (r = 0.93; P less than 0.01), a result also seen in the physical model.

  13. Radiative capture reactions and spectroscopy of multipolar anions in the framework of Gamow Shell Model

    Small open quantum systems, whose properties are profoundly affected by the environment of continuum states, are intensely studied in various fields of Physics: nuclear physics, atomic and molecular physics, quantum optics, etc. These different many-body systems, in spite of their specific features, have generic properties which are common to all weakly bound or unbound systems close to the threshold. Coupling to the continuum is essential to describe the low-energy nuclear reactions of astrophysical interest, the formation of halo states in nuclei, atomic clusters and dipolar anions, or the near-threshold two neutron and alpha particle correlations (clustering). Recently, the open quantum system extension of the nuclear shell model, the Gamow shell model (GSM), based on the Berggren ensemble, has been applied successfully for the description of resonant states spectra in atomic nuclei. The coupled-channel formulation of the GSM (GSM-CC) allows to describe various low-energy nuclear reactions. In this work, the GSM-CC is formulated and applied for the description of proton/neutron radiative capture reactions of astrophysical interest, such as: 17F(p, γ)18Ne, 7Be(p, γ)8B and 7Li(n, γ)8Li. Moreover, for the first time, the GSM has been applied in atomic physics for the description of spectra of dipolar anions. Systematic investigation of the hydrogen cyanide dipolar anion (HCN-) allowed to identify the collective bands of states both in the strong coupling regime, for weakly bound halo states, and in the weak coupling regime above the dissociation threshold. In the strong coupling regime, KJ = 0 anion a rotational band has been found. Above the threshold, KJ quantum number is not conserved. Resonances in this regime form rotational bands according to the angular momentum of the rotating molecule, whereas the band head energies and the lifetimes depend predominantly on the external electron wave function. (author)

  14. Transferred multipolar atom model for 10β,17β-dihydroxy-17α-methylestr-4-en-3-one dihydrate obtained from the biotransformation of methyloestrenolone.

    Faroque, Muhammad Umer; Yousuf, Sammer; Zafar, Salman; Choudhary, M Iqbal; Ahmed, Maqsood

    2016-05-01

    Biotransformation is the structural modification of compounds using enzymes as the catalysts and it plays a key role in the synthesis of pharmaceutically important compounds. 10β,17β-Dihydroxy-17α-methylestr-4-en-3-one dihydrate, C19H28O3·2H2O, was obtained from the fungal biotransformation of methyloestrenolone. The structure was refined using the classical independent atom model (IAM) and a transferred multipolar atom model using the ELMAM2 database. The results from the two refinements have been compared. The ELMAM2 refinement has been found to be superior in terms of the refinement statistics. It has been shown that certain electron-density-derived properties can be calculated on the basis of the transferred parameters for crystals which diffract to ordinary resolution. PMID:27146568

  15. The economy of Russia in multipolar world

    Lapo, Valentina

    2013-01-01

    There have been several poles of development: USA, Europe, and China are formatted in the world economy. How does the multipolar world economy influence the Russian economy’s development? The studies based on the main results of new economic geography and gravity theory concerning the spatial concentration of production in the economy of countries and large regions. We propose the econometric model of industrial production, employment, investment, and income under expectation about the multip...

  16. The role of multipolar magnetic fields in pulsar magnetospheres

    Asséo, E; Asseo, Estelle; Khechinashvili, David

    2002-01-01

    We explore the role of complex multipolar magnetic fields in determining physical processes near the surface of rotation powered pulsars. We model the actual magnetic field as the sum of global dipolar and star-centered multipolar fields. In configurations involving axially symmetric and uniform multipolar fields, 'neutral points' and 'neutral lines' exist close to the stellar surface. Also, the curvature radii of magnetic field lines near the stellar surface can never be smaller than the stellar radius, even for very high order multipoles. Consequently, such configurations are unable to provide an efficient pair creation process above pulsar polar caps, necessary for plasma mechanisms of generation of pulsar radiation. In configurations involving axially symmetric and non-uniform multipoles, the periphery of the pulsar polar cap becomes fragmented into symmetrically distributed narrow sub-regions where curvature radii of complex magnetic field lines are less than the radius of the star. The pair production p...

  17. Strategies for Business Schools in a Multi-Polar World

    Dameron, Stephanie; Durand, Thomas

    2013-01-01

    Purpose: The purpose of this paper is to examine the contours of the emerging business education and institutions in a multi-polar world and to identify the causes of the strategic convergence of management education, to explore the limitations of the dominant models of management education and to propose a range of strategic alternatives for…

  18. Multipolar interference effects in nanophotonics

    Liu, Wei

    2016-01-01

    Scattering of electromagnetic waves by an arbitrary nanoscale object can be characterized by a multipole decomposition of the electromagnetic field that allows to describe the scattering intensity and radiation pattern through interferences of dominating excited multipole modes. In modern nanophotonics, both generation and interference of multipole modes start to play an indispensable role, and they enable nanoscale manipulation of light with many related applications. Here we review the multipolar interference effects in metallic, metal-dielectric, and dielectric nanostructures, and suggest a comprehensive view on many phenomena involving the interferences of electric, magnetic and toroidal multipoles, which drive a number of recently discussed effects in nanophotonics such as unidirectional scattering, effective optical antiferromagnetism, generalized Kerker scattering with controlled angular patterns, generalized Brewster angle, and nonradiating optical anapoles. We further discuss other types of possible ...

  19. Multipolar representation of protein structure

    Bourne Philip E

    2006-05-01

    Full Text Available Abstract Background That the structure determines the function of proteins is a central paradigm in biology. However, protein functions are more directly related to cooperative effects at the residue and multi-residue scales. As such, current representations based on atomic coordinates can be considered inadequate. Bridging the gap between atomic-level structure and overall protein-level functionality requires parameterizations of the protein structure (and other physicochemical properties in a quasi-continuous range, from a simple collection of unrelated amino acids coordinates to the highly synergistic organization of the whole protein entity, from a microscopic view in which each atom is completely resolved to a "macroscopic" description such as the one encoded in the three-dimensional protein shape. Results Here we propose such a parameterization and study its relationship to the standard Euclidian description based on amino acid representative coordinates. The representation uses multipoles associated with residue Cα coordinates as shape descriptors. We demonstrate that the multipoles can be used for the quantitative description of the protein shape and for the comparison of protein structures at various levels of detail. Specifically, we construct a (dissimilarity measure in multipolar configuration space, and show how such a function can be used for the comparison of a pair of proteins. We then test the parameterization on a benchmark set of the protein kinase-like superfamily. We prove that, when the biologically relevant portions of the proteins are retained, it can robustly discriminate between the various families in the set in a way not possible through sequence or conventional structural representations alone. We then compare our representation with the Cartesian coordinate description and show that, as expected, the correlation with that representation increases as the level of detail, measured by the highest rank of multipoles

  20. Multipolar expansion of orbital angular momentum modes

    Molina-Terriza, Gabriel

    2008-01-01

    In this letter a general method for expanding paraxial beams into multipolar electromagnetic fields is presented. This method is applied to the expansion of paraxial modes with orbital angular momentum (OAM), showing how the paraxial OAM is related to the general angular momentum of an electromagnetic wave. This method can be extended to quasi-paraxial beams, i.e. highly focused laser beams. Some applications to the control of electronic transitions in atoms are discussed.

  1. Polarizable multipolar electrostatics for cholesterol

    Fletcher, Timothy L.; Popelier, Paul L. A.

    2016-08-01

    FFLUX is a novel force field under development for biomolecular modelling, and is based on topological atoms and the machine learning method kriging. Successful kriging models have been obtained for realistic electrostatics of amino acids, small peptides, and some carbohydrates but here, for the first time, we construct kriging models for a sizeable ligand of great importance, which is cholesterol. Cholesterol's mean total (internal) electrostatic energy prediction error amounts to 3.9 kJ mol-1, which pleasingly falls below the threshold of 1 kcal mol-1 often cited for accurate biomolecular modelling. We present a detailed analysis of the error distributions.

  2. SQUID-based multichannel system for Magnetoencephalography

    Rombetto, S; Vettoliere, A; Trebeschi, A; Rossi, R; Russo, M

    2013-01-01

    Here we present a multichannel system based on superconducting quantum interference devices (SQUIDs) for magnetoencephalography (MEG) measurements, developed and installed at Istituto di Cibernetica (ICIB) in Naples. This MEG system, consists of 163 full integrated SQUID magnetometers, 154 channels and 9 references, and has been designed to meet specifications concerning noise, dynamic range, slew rate and linearity through optimized design. The control electronics is located at room temperature and all the operations are performed inside a Magnetically Shielded Room (MSR). The system exhibits a magnetic white noise level of approximatively 5 fT/Hz1=2. This MEG system will be employed for both clinical and routine use. PACS numbers: 74.81.Fa, 85.25.Hv, 07.20.Mc, 85.25.Dq, 87.19.le, 87.85.Ng

  3. Magnetoencephalography from signals to dynamic cortical networks

    Aine, Cheryl

    2014-01-01

    "Magnetoencephalography (MEG) provides a time-accurate view into human brain function. The concerted action of neurons generates minute magnetic fields that can be detected---totally noninvasively---by sensitive multichannel magnetometers. The obtained millisecond accuracycomplements information obtained by other modern brain-imaging tools. Accurate timing is quintessential in normal brain function, often distorted in brain disorders. The noninvasiveness and time-sensitivityof MEG are great assets to developmental studies, as well. This multiauthored book covers an ambitiously wide range of MEG research from introductory to advanced level, from sensors to signals, and from focal sources to the dynamics of cortical networks. Written by active practioners of this multidisciplinary field, the book contains tutorials for newcomers and chapters of new challenging methods and emerging technologies to advanced MEG users. The reader will obtain a firm grasp of the possibilities of MEG in the study of audition, vision...

  4. Optical multipolar spread functions of an aplanatic imaging system

    Rouxel, Jérémy R.; Toury, Timothée

    2016-07-01

    The electromagnetic field near the focus of a perfect imaging system is calculated for different multipolar sources that play an important role in the radiation of nanostructures. Those multipoles are the exact and extended multipoles occurring in electrodynamics. The theory of diffraction of vector waves is reviewed rigorously for a dipolar radiation and applied to the imaging of multipolar sources. Different geometries are considered in order to connect with experiments and the multipolar spread functions are given in a ready-to-use format up to the octupolar order, in the general case and in the paraxial approximation. Defocus imaging is finally considered to provide a first step toward multipolar imaging.

  5. Classification of spin and multipolar squeezing

    Yukawa, Emi; Nemoto, Kae

    2016-06-01

    We investigate various types of squeezing in a collective su(2J+1) system consisting of spin-J particles (J\\gt 1/2). We show that squeezing in the collective su(2J+1) system can be classified into unitary equivalence classes, each of which is characterized by a set of squeezed and anti-squeezed observables forming an su(2) subalgebra in the su(2J+1) algebra. The dimensionality of the unitary equivalence class is found to be fundamentally related to its squeezing limit. We also demonstrate the classification of squeezing among the spin and multipolar observables in a collective su(4) system.

  6. Magnetoencephalography (MEG) and other neurophysiological investigations.

    Paetau, Ritva; Mohamed, Ismail S

    2013-01-01

    Cortical generators of epileptic and certain physiological activity can be localized noninvasively by magnetoencephalography (MEG). MEG detects weak magnetic fields produced by the postsynaptic currents of pyramidal cortical cells in sulcal walls. Unlike EEG, MEG signals are not distorted by edema or bone defects, and unlike fMRI, abnormal hemodynamics do not alter the MEG. The patient's head is centered inside a helmet housing over a hundred magnetic field sensors. Cortical generators of MEG signals are determined with a useful spatial resolution and an excellent time resolution, which enable tracking of brain activity in successive points of, for example, an epileptic network. MEG sources can be co-registered and visualized on magnetic resonance images (MRI). MEG is highly sensitive for the detection of interictal epileptic discharges, and present techniques allow some degree of head movements enabling ictal recordings also. MEG is also useful for localizing the somatosensory, visual, and language areas before tailored surgery in the vicinity of eloquent cortex. In conjunction with other noninvasive modalities MEG provides nonredundant data in one-third of epilepsy surgery patients. Clinical MEG utilization is mainly focused on presurgical localization of the epileptogenic zone and eloquent cortex in epilepsy surgery candidates, including patients with Landau-Kleffner syndrome. However, MEG is also an excellent noninvasive tool to study the source distribution in childhood epilepsy syndromes and epileptic encephalopathies. PMID:23622195

  7. Multipolar spindle pole coalescence is a major source of kinetochore mis-attachment and chromosome mis-segregation in cancer cells.

    William T Silkworth

    Full Text Available Many cancer cells display a CIN (Chromosome Instability phenotype, by which they exhibit high rates of chromosome loss or gain at each cell cycle. Over the years, a number of different mechanisms, including mitotic spindle multipolarity, cytokinesis failure, and merotelic kinetochore orientation, have been proposed as causes of CIN. However, a comprehensive theory of how CIN is perpetuated is still lacking. We used CIN colorectal cancer cells as a model system to investigate the possible cellular mechanism(s underlying CIN. We found that CIN cells frequently assembled multipolar spindles in early mitosis. However, multipolar anaphase cells were very rare, and live-cell experiments showed that almost all CIN cells divided in a bipolar fashion. Moreover, fixed-cell analysis showed high frequencies of merotelically attached lagging chromosomes in bipolar anaphase CIN cells, and higher frequencies of merotelic attachments in multipolar vs. bipolar prometaphases. Finally, we found that multipolar CIN prometaphases typically possessed gamma-tubulin at all spindle poles, and that a significant fraction of bipolar metaphase/early anaphase CIN cells possessed more than one centrosome at a single spindle pole. Taken together, our data suggest a model by which merotelic kinetochore attachments can easily be established in multipolar prometaphases. Most of these multipolar prometaphase cells would then bi-polarize before anaphase onset, and the residual merotelic attachments would produce chromosome mis-segregation due to anaphase lagging chromosomes. We propose this spindle pole coalescence mechanism as a major contributor to chromosome instability in cancer cells.

  8. Measuring cerebral hemodynamics with a modified magnetoencephalography system

    Magnetoencephalography (MEG) systems are designed to noninvasively measure magnetic fields produced by neural electrical currents. This project examines the possibility of measuring hemodynamics with an MEG system that has been modified with dc electromagnets to measure magnetic susceptibility while maintaining the capability of measuring neural dynamics. A forward model is presented that simulates the interaction of an applied magnetic field with changes in magnetic susceptibility in the brain associated with hemodynamics. Model predictions are compared with an experiment where deionized water was pumped into an inverted flask under the MEG sensor array of superconducting quantum interference device (SQUID) gradiometers (R2 = 0.98, p < 0.001). The forward model was used to simulate the SQUID readouts from hemodynamics in the scalp and brain induced by performing the Valsalva maneuver. Experimental human subject recordings (N = 10) were made from the prefrontal region during Valsalva using concurrent measurement with the modified MEG system and near-infrared spectroscopy (NIRS). The NIRS deoxyhemoglobin signal was found to correlate significantly with the SQUID readouts (R2 = 0.84, p < 0.01). SQUID noise was found to increase with the applied field, which will need to be mitigated in future work. These results demonstrate the potential and technical challenges of measuring cerebral hemodynamics with a modified MEG system. (paper)

  9. Magnetoencephalography in studies of human cognitive brain function.

    Näätänen, R; Ilmoniemi, R J; Alho, K

    1994-09-01

    Magnetoencephalography provides a new dimension to the functional imaging of the brain. The cerebral magnetic fields recorded noninvasively enable the accurate determination of locations of cerebral activity with an uncompromized time resolution. The first whole-scalp sensor arrays have just recently come into operation, and significant advances are to be expected in both neurophysiological and cognitive studies, as well as in clinical practice. However, although the accuracy of locating isolated sources of brain activity has improved, identification of multiple simultaneous sources can still be a problem. Therefore, attempts are being made to combine magnetoencephalography with other brain-imaging methods to improve spatial localization of multiple sources and, simultaneously, to achieve a more complete characterization of different aspects of brain activity during cognitive processing. Owing to its good time resolution and considerably better spatial accuracy than that provided by EEG, magnetoencephalography holds great promise as a tool for revealing information-processing sequences of the human brain. PMID:7529443

  10. Magnetoencephalography: From first steps to clinical applications

    Ilmoniemi, Risto

    2014-03-01

    Magnetoencephalography (MEG), the study of femtotesla-range magnetic fields produced by neuronal currents in the brain, originated in the 1960's. After Baule and McFee's (Am Heart J 66:95-6,1963) measurement of the cardiac magnetic field using induction-coil sensors, Cohen (Science 16:784-6, 1968) used a similar multi-turn coil to detect the brain's alpha rhythm. The introduction of the superconducting quantum interference device (SQUID) by Zimmerman et al. (J Appl Phys 41: 1572-80) improved the sensitivity of magnetic sensing by several orders of magnitude, making MEG practical. The SQUID enabled the unaveraged recording of spontaneous brain rhythms (D. Cohen, Science 175:664-6, 1972) as well as evoked magnetic fields (Brenner et al., Science 190:480-2, 1975; Teyler et al., Life Sci 17:683-91, 1975). Subsequently, a large number of evoked-field variants were demonstrated. The main benefit of MEG is its ability to locate electrical activity in the brain at high temporal resolution. For practical work, we need large arrays of highly sensitive SQUIDs; such arrays were first built in the 1990's (Knuutila et al., IEEE Trans Magn 29:3315-20, 1993). While the intrinsic spatial accuracy of locating sources with well-calibrated large sensor arrays is better than one millimeter, uncertainties in determining the location and geometry of the cortex with respect to the array may lead to source-location errors of 5-10 mm or more. These errors could be reduced to 1 mm if one could obtain the structural image of the brain with the same sensors that are used for MEG and if the conductivity geometry of the head would be accurately known. This may indeed be possible if MRI is recorded with SQUIDs (McDermott et al., PNAS 21:7857-61, 2004) concurrently with MEG (Zotev et al., J Magn Reson 194:115-20, 2008), especially if large arrays are developed (Vesanen et al., Magn Reson Med 69:1795-1804, 2013); the conductivity distribution of the head might be possible to determine with current

  11. The precise ICC measurement of the high multipolarity transitions

    The methods of γ-spectroscopy are used to measure internal conversion coefficients (ICC) on the K-shell and total ICC for M4,E4,E5-multipolarity transitions. The research is carried out using the 202,204Pb, 197Pt,114In isomers. The data obtained prove that the observed systematic excess of theoretical ICC for M4-multipolarity transitions as compared with the experimental values is most probably connected with the contribution of ''intranuclear'' conversion

  12. Nesting-driven multipolar order in CeB6 from photoemission tomography

    Koitzsch, A,; Heming, N.; Knupfer, M.; Büchner, B.; Portnichenko, P. Y.; Dukhnenko, A. V.; Shitsevalova, N. Y.; Filipov, V. B.; Lev, L. L.; Strocov, V. N.; Ollivier, J.; Inosov, D. S.

    2016-01-01

    Some heavy fermion materials show so-called hidden-order phases which are invisible to many characterization techniques and whose microscopic origin remained controversial for decades. Among such hidden-order compounds, CeB6 is of model character due to its simple electronic configuration and crystal structure. Apart from more conventional antiferromagnetism, it shows an elusive phase at low temperatures, which is commonly associated with multipolar order. Here we show that this phase roots i...

  13. Scattering from bare soils: C-band multipolarization scatterometer measurements

    Casarano, Domenico; Buono, G.; Paparella, F.; Posa, Francesco; Sabatelli, Vincenzo

    1998-11-01

    Multi-angle, multi-polarization C-band backscattering measurements were performed over selected bare soil areas. To perform these measurements, an FM-CW radar has been designed and assembled. This device has the capability of resolving independent samples within the antenna footprint area, thus allowing range discrimination and improving the signal statistics. Two areas with different degrees of roughness and dielectric constants were selected and set up. Co-polarized backscattering coefficients were measured for incidence angles between 23 degrees and 60 degrees. To perform a model analysis of the backscattering properties, 'ground truth' data, including surface roughness profiles and soil moisture values (directly related to dielectric constant) were also collected. The 'classical' parameters, used to describe surface roughness, showed a wide spreading. This evidence and the data resulting from ground truth campaigns over many European test sites suggested an alternative description of surface roughness, based on the self-similarity (fractal) properties. The surfaces have therefore been described as fBm (Fractional Brownian Motion) processes, and their backscattering response has been theoretically modeled by a numerical simulation (in 3-D in order to also take into account anisotropy effects) in Kirchhoff approximation. The experimental data have been analyzed with both asymptotic models (IEM) considering a classical statistical description, and with the numerical simulation applied to fBm surfaces.

  14. Smoother thrust on multi-polar type linear DC motor

    Wakiwaka, H.; Senoh, S.; Yajima, H; Yamada, H. [Shinshu Univ., Wakasato, Nagano (Japan). Faculty of Engineering; Oda, J. [Ohkura Electric Co., Ltd., Shirako, Wakou (Japan)

    1997-09-01

    A LDM has the merits of a high response and a direct linear motion. Therefore, a LDM is used widely in the fields of Factory Automation (FA). As compared with a mono-polar type Linear DC Motor (LDM), it is possible for a multi-polar type LDM to have a longer stroke and more thrust with thin shape. However, there are thrust ripple on multi-polar type one. In this paper, a design to prevent thrust ripple is discussed. In order to make a smoother thrust on multi-polar type LDM, the structure of the LDM is set as a 2-phase coil type. This paper clarifies that the thrust ripple of the LDM has the minimum value of 1.68%, the pole pitch of 15 mm, the coil width of 12 mm and the permanent magnet width of 10 mm.

  15. Magnetoencephalography as a Putative Biomarker for Alzheimer's Disease

    Edward Zamrini

    2011-01-01

    Full Text Available Alzheimer's Disease (AD is the most common dementia in the elderly and is estimated to affect tens of millions of people worldwide. AD is believed to have a prodromal stage lasting ten or more years. While amyloid deposits, tau filaments, and loss of brain cells are characteristics of the disease, the loss of dendritic spines and of synapses predate such changes. Popular preclinical detection strategies mainly involve cerebrospinal fluid biomarkers, magnetic resonance imaging, metabolic PET scans, and amyloid imaging. One strategy missing from this list involves neurophysiological measures, which might be more sensitive to detect alterations in brain function. The Magnetoencephalography International Consortium of Alzheimer's Disease arose out of the need to advance the use of Magnetoencephalography (MEG, as a tool in AD and pre-AD research. This paper presents a framework for using MEG in dementia research, and for short-term research priorities.

  16. Sensing with multipolar second harmonic generation from spherical metallic nanoparticles.

    Butet, Jérémy; Russier-Antoine, Isabelle; Jonin, Christian; Lascoux, Noëlle; Benichou, Emmanuel; Brevet, Pierre-François

    2012-03-14

    We show that sensing in the nonlinear optical regime using multipolar surface plasmon resonances is more sensitive in comparison to sensing in the linear optical regime. Mie theory, and its extension to the second harmonic generation from a metallic nanosphere, is used to describe multipolar second harmonic generation from silver metallic nanoparticles. The standard figure of merit of a potential plasmonic sensor based on this principle is then calculated. We finally demonstrate that such a sensor is more sensitive to optical refraction index changes occurring in the vicinity of the metallic nanoparticle than its linear counterpart. PMID:22375818

  17. Neural Signatures of Phonetic Learning in Adulthood: A Magnetoencephalography Study

    Zhang, Yang; Kuhl, Patricia K.; Imada, Toshiaki; Iverson, Paul; Pruitt, John; Stevens, Erica B.; Kawakatsu, Masaki; Tohkura, Yoh'ichi; Nemoto, Iku

    2009-01-01

    The present study used magnetoencephalography (MEG) to examine perceptual learning of American English /r/ and /l/ categories by Japanese adults who had limited English exposure. A training software program was developed based on the principles of infant phonetic learning, featuring systematic acoustic exaggeration, multi-talker variability, visible articulation, and adaptive listening. The program was designed to help Japanese listeners utilize an acoustic dimension relevant for phonemic cat...

  18. Design of outer-rotor type multipolar SR motor for electric vehicle

    In this paper, we design an outer-rotor type multipolar switched reluctance (SR) motor, and examine an application of the SR motor to an electric vehicle (EV). The design is based on a nonlinear magnetic circuit model proposed by the authors. Using the model, we can calculate dynamic characteristics of a SR motor accurately. Furthermore, by combining the nonlinear magnetic circuit model with a motor drive circuit and motion equation of an EV, we can predict dynamic characteristics such as the maximum speed, acceleration torque, and a battery current of the EV

  19. Design of outer-rotor type multipolar SR motor for electric vehicle

    Nakamura, Kenji; Suzuki, Yosuke; Goto, Hiroki; Ichinokura, Osamu

    2005-04-01

    In this paper, we design an outer-rotor type multipolar switched reluctance (SR) motor, and examine an application of the SR motor to an electric vehicle (EV). The design is based on a nonlinear magnetic circuit model proposed by the authors. Using the model, we can calculate dynamic characteristics of a SR motor accurately. Furthermore, by combining the nonlinear magnetic circuit model with a motor drive circuit and motion equation of an EV, we can predict dynamic characteristics such as the maximum speed, acceleration torque, and a battery current of the EV.

  20. Beam engineering for selective and enhanced coupling to multipolar resonances

    Das, Tanya; Schuller, Jon A

    2015-01-01

    Multipolar electromagnetic phenomena in sub-wavelength resonators are at the heart of metamaterial science and technology. In this letter, we demonstrate selective and enhanced coupling to specific multipole resonances via beam engineering. We first derive an analytical method for determining the scattering and absorption of spherical nanoparticles (NPs) that depends only on the local electromagnetic field quantities within an inhomogeneous beam. Using this analytical technique, we demonstrate the ability to drastically manipulate the scattering properties of a spherical NP by varying illumination properties and demonstrate the excitation of a longitudinal quadrupole mode that cannot be accessed with conventional illumination. This work enhances the understanding of fundamental light-matter interactions in metamaterials, and lays the foundation for researchers to identify, quantify, and manipulate multipolar light-matter interactions through optical beam engineering.

  1. Optical Torque from Enhanced Scattering by Multipolar Plasmonic Resonance

    Lee, Yoonkyung E; Jin, Dafei; Fang, Nicholas

    2014-01-01

    We present a theoretical study of the optical angular momentum transfer from a circularly polarized plane wave to thin metal nanoparticles of different rotational symmetries. While absorption has been regarded as the predominant mechanism of torque generation on the nanoscale, we demonstrate numerically how the contribution from scattering can be enhanced by using multipolar plasmon resonance. The multipolar modes in non-circular particles can convert the angular momentum carried by the scattered field, thereby producing scattering-dominant optical torque, while a circularly symmetric particle cannot. Our results show that the optical torque induced by resonant scattering can contribute to 80% of the total optical torque in gold particles. This scattering-dominant torque generation is extremely mode-specific, and deserves to be distinguished from the absorption-dominant mechanism. Our findings might have applications in optical manipulation on the nanoscale as well as new designs in plasmonics and metamateria...

  2. Beam engineering for selective and enhanced coupling to multipolar resonances

    Das, Tanya; Iyer, Prasad P.; DeCrescent, Ryan A.; Schuller, Jon A.

    2015-12-01

    Multipolar electromagnetic phenomena in subwavelength resonators are at the heart of metamaterial science and technology. In this Rapid Communication, we demonstrate selective and enhanced coupling to specific multipole resonances via beam engineering. We first derive an analytical method for determining the scattering and absorption of spherical nanoparticles (NPs) that depends only on the local electromagnetic field quantities within an inhomogeneous beam. Using this analytical technique, we demonstrate the ability to drastically manipulate the scattering properties of a spherical NP by varying illumination properties and demonstrate the excitation of a longitudinal quadrupole mode that cannot be accessed with conventional illumination. This work enhances the understanding of fundamental light-matter interactions in metamaterials and lays the foundation for researchers to identify, quantify, and manipulate multipolar light-matter interactions through optical beam engineering.

  3. THE EU-US RELATIONS IN AN EMERGING MULTIPOLAR WORLD

    Roxana Hincu

    2014-01-01

    In the context of an emerging multipolar world, the transatlantic partnership faces various challenges in the attempt to maintain the Western-shaped and dominated liberal order. This article aims to synthesize and rationalize the central argumentative positions on the ever-evolving transatlantic relationship provided by the following theories of international relations: neorealism, neoliberalism and constructivism. A combination of the main assumptions of the three approaches brings useful in...

  4. First-Strike Stability in a Multipolar World

    Melvin Best; Jerome Bracken

    1995-01-01

    First-strike stability in a multipolar world measures the incentives of all major nuclear weapon countries, in all possible coalitions, to refrain from preemptive attack. The analysis integrates the interactions of offensive weapon arsenals, vulnerable offensive weapons within these arsenals, defensive weapons, and value targets reflecting the national assets at stake. In the previously-dominant bipolar paradigm, when the United States and the Soviet Union possessed almost all of the strategi...

  5. A multipolar SR motor and its application in EV

    In order to bring out the advanced features of EVs, a direct-drive (DD) with in-wheel (IW) layout has been considered, but it requires more motors than the conventional layout and the motors will be used in a hard environment. Because switched reluctance motors (SRMs) are simple and strong, we have developed a new outer-rotor-type multipolar SRM suitable for DD-IW EVs through simulations and experiments. We have implemented the developed SRMs into a prototype EV. This is the first-ever in-vehicle research to our knowledge; the developing process and the road test results will bring many useful guidelines for future developments

  6. Impact of polydispersity on multipolar resonant scattering in emulsions.

    Mascaro, Benoit; Brunet, Thomas; Poncelet, Olivier; Aristégui, Christophe; Raffy, Simon; Mondain-Monval, Olivier; Leng, Jacques

    2013-04-01

    The influence of size polydispersity on the resonant acoustic properties of dilute emulsions, made of fluorinated-oil droplets, is quantitatively investigated. Ultrasound attenuation and dispersion measurements on various samples with controlled size polydispersities, ranging from 1% to 13%, are found to be in excellent agreement with predictions based on the independent scattering approximation. By relating the particle-size distribution of the synthesized emulsions to the quality factor of the predicted multipolar resonances, the number of observable acoustic resonances is shown to be imposed by the sample polydispersity. These results are briefly discussed into the context of metamaterials for which scattering resonances are central to their effective properties. PMID:23556570

  7. Multipolar localized resonances for multi-band metamaterial perfect absorbers

    A metamaterial structure, comprising of metallic circular micro-discs (gold or aluminum) separated from a metallic thin film by a dielectric zinc sulphide film, behaves as a multi-band perfect absorber at infra red wavelengths due to the excitation of multipole resonances. With micro-discs of 3.2 μm diameter, the fabricated metamaterial absorber shows peak absorbance of over 90% in multiple selected bands spanning the 3–14 μm wavelengths. Absorption bands corresponding to the different resonance modes have been measured and computational simulations show these resonances originate from the higher order multipolar resonances of the disk. (special issue article)

  8. Multichannel System Based on a High Sensitivity Superconductive Sensor for Magnetoencephalography

    Sara Rombetto

    2014-07-01

    Full Text Available We developed a multichannel system based on superconducting quantum interference devices (SQUIDs for magnetoencephalography measurements. Our system consists of 163 fully-integrated SQUID magnetometers, 154 channels and 9 references, and all of the operations are performed inside a magnetically-shielded room. The system exhibits a magnetic field noise spectral density of approximatively 5 fT/Hz1=2. The presented magnetoencephalography is the first system working in a clinical environment in Italy.

  9. Anatomy of the Binary Black Hole Recoil: A Multipolar Analysis

    Schnittman, Jeremy; Buonanno, Alessandra; vanMeter, James R.; Baker, John G.; Boggs, William D.; Centrella, Joan; Kelly, Bernard J.; McWilliams, Sean T.

    2007-01-01

    We present a multipolar analysis of the recoil velocity computed in recent numerical simulations of binary black hole coalescence, for both unequal masses and non-zero, non-precessing spins. We show that multipole moments up to and including 1 = 4 are sufficient to accurately reproduce the final recoil velocity (= 98%) and that only a few dominant modes contribute significantly to it (2 95%). We describe how the relative amplitude, and more importantly, the relative phase, of these few modes control the way in which the recoil builds up throughout the inspiral, merger, and ring-down phases. We also find that the numerical results can be reproduced, to a high level of accuracy, by an effective Newtonian formula for the multipole moments obtained by replacing in the Newtonian formula the radial separation with an effective radius computed from the numerical data. Beyond the merger, the numerical results are reproduced by a superposition of three Kerr quasi-normal modes. Analytic formulae, obtained by expressing the multipole moments in terms of the fundamental QNMs of a Kerr BH, are able to explain the onset and amount of '.anti-kick" for each of the simulations. Lastly, we apply this multipolar analysis to understand the remarkable difference between the amplitudes of planar and non-planar kicks for equal-mass spinning black holes.

  10. Investigating the neural correlates of the Stroop effect with magnetoencephalography.

    Galer, Sophie; Op De Beeck, Marc; Urbain, Charline; Bourguignon, Mathieu; Ligot, Noémie; Wens, Vincent; Marty, Brice; Van Bogaert, Patrick; Peigneux, Philippe; De Tiège, Xavier

    2015-01-01

    Reporting the ink color of a written word when it is itself a color name incongruent with the ink color (e.g. "red" printed in blue) induces a robust interference known as the Stroop effect. Although this effect has been the subject of numerous functional neuroimaging studies, its neuronal substrate is still a matter of debate. Here, we investigated the spatiotemporal dynamics of interference-related neural events using magnetoencephalography (MEG) and voxel-based analyses (SPM8). Evoked magnetic fields (EMFs) were acquired in 12 right-handed healthy subjects performing a color-word Stroop task. Behavioral results disclosed a classic interference effect with longer mean reaction times for incongruent than congruent stimuli. At the group level, EMFs' differences between incongruent and congruent trials spanned from 380 to 700 ms post-stimulus onset. Underlying neural sources were identified in the left pre-supplementary motor area (pre-SMA) and in the left posterior parietal cortex (PPC) confirming the role of these regions in conflict processing. PMID:24752907

  11. Noise-free magnetoencephalography recordings of brain function

    Perhaps the greatest impediment to acquiring high-quality magnetoencephalography (MEG) recordings is the ubiquitous ambient magnetic field noise. We have designed and built a whole-head MEG system using a helmet-like superconducting imaging surface (SIS) surrounding the array of superconducting quantum interference device (SQUID) magnetometers used to measure the MEG signal. We previously demonstrated that the SIS passively shields the SQUID array from ambient magnetic field noise, independent of frequency, by 25-60 dB depending on sensor location. SQUID 'reference sensors' located on the outside of the SIS helmet measure ambient magnetic fields in very close proximity to the MEG magnetometers while being nearly perfectly shielded from all sources in the brain. The fact that the reference sensors measure no brain signal yet are located in close proximity to the MEG sensors enables very accurate estimation and subtraction of the ambient field noise contribution to the MEG sensors using an adaptive algorithm. We have demonstrated total ambient noise reduction factors in excess of 106 (>120 dB). The residual noise for most MEG SQUID channels is at or near the intrinsic SQUID noise floor, typically 2-3 f T Hz-1/2. We are recording MEG signals with greater signal-to-noise than equivalent EEG measurements

  12. Noise-free magnetoencephalography recordings of brain function

    Volegov, P.; Matlachov, A.; Mosher, J.; Espy, M. A.; Kraus, R. H., Jr.

    2004-05-01

    Perhaps the greatest impediment to acquiring high-quality magnetoencephalography (MEG) recordings is the ubiquitous ambient magnetic field noise. We have designed and built a whole-head MEG system using a helmet-like superconducting imaging surface (SIS) surrounding the array of superconducting quantum interference device (SQUID) magnetometers used to measure the MEG signal. We previously demonstrated that the SIS passively shields the SQUID array from ambient magnetic field noise, independent of frequency, by 25-60 dB depending on sensor location. SQUID 'reference sensors' located on the outside of the SIS helmet measure ambient magnetic fields in very close proximity to the MEG magnetometers while being nearly perfectly shielded from all sources in the brain. The fact that the reference sensors measure no brain signal yet are located in close proximity to the MEG sensors enables very accurate estimation and subtraction of the ambient field noise contribution to the MEG sensors using an adaptive algorithm. We have demonstrated total ambient noise reduction factors in excess of 106 (>120 dB). The residual noise for most MEG SQUID channels is at or near the intrinsic SQUID noise floor, typically 2-3 f T Hz-1/2. We are recording MEG signals with greater signal-to-noise than equivalent EEG measurements.

  13. Noise-free magnetoencephalography recordings of brain function

    Volegov, P; Matlachov, A; Mosher, J; Espy, M A; Kraus, R H Jr. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2004-05-21

    Perhaps the greatest impediment to acquiring high-quality magnetoencephalography (MEG) recordings is the ubiquitous ambient magnetic field noise. We have designed and built a whole-head MEG system using a helmet-like superconducting imaging surface (SIS) surrounding the array of superconducting quantum interference device (SQUID) magnetometers used to measure the MEG signal. We previously demonstrated that the SIS passively shields the SQUID array from ambient magnetic field noise, independent of frequency, by 25-60 dB depending on sensor location. SQUID 'reference sensors' located on the outside of the SIS helmet measure ambient magnetic fields in very close proximity to the MEG magnetometers while being nearly perfectly shielded from all sources in the brain. The fact that the reference sensors measure no brain signal yet are located in close proximity to the MEG sensors enables very accurate estimation and subtraction of the ambient field noise contribution to the MEG sensors using an adaptive algorithm. We have demonstrated total ambient noise reduction factors in excess of 10{sup 6} (>120 dB). The residual noise for most MEG SQUID channels is at or near the intrinsic SQUID noise floor, typically 2-3 f T Hz{sup -1/2}. We are recording MEG signals with greater signal-to-noise than equivalent EEG measurements.

  14. Issues on Multi-polarization of GNSS-R for Passive Radar Detection

    Wan Wei

    2015-01-01

    Full Text Available GNSS Reflectometry (GNSS-R is a currently developed remote sensing technology which belongs to the passive radar domain. This paper aims to deal with some issues on multi-polarization of GNSS-R technology. Four different polarization patterns of the received GNSS-R signal are discussed, including rl, rr, rv, rh. For each polarization, formulas for calculating the surface reflectivity (Γ using dielectric constant (ε and satellite elevation angle (θ are derivated. The rationality of these formulas is validated using data from a ground-based GNSS-R soil moisture experiment. The results of this research can provide references for further GNSS-R research, including simulation, experiment design, model development and data processing.

  15. Multipolar interference for non-reciprocal nonlinear generation

    Poutrina, Ekaterina

    2015-01-01

    We show that nonlinear multipolar interference allows achieving not only unidirectional, but also non-reciprocal nonlinear generation from a nanoelement, with the direction of the nonlinearly produced light decoupled from that of at least one or several of the excitation beams. Alternatively, it may allow inhibiting the specified nonlinear response in a nanoelement or in its periodic arrangement by reversing the direction of one of the pumps. The described phenomena exploit the fact that, contrary to the linear response case, nonlinear magneto-electric interference stems from a combination of additive and multiplicative processes and includes an interference between various terms within the electric and magnetic partial waves themselves. We demonstrate the introduced concept numerically using an example of a plasmonic dimer geometry with realistic material parameters.

  16. Anatomy of the binary black hole recoil: A multipolar analysis

    Schnittman, Jeremy D; van Meter, James R; Baker, John G; Boggs, William D; Centrella, Joan; Kelly, Bernard J; McWilliams, Sean T

    2007-01-01

    We present a multipolar analysis of the gravitational recoil computed in recent numerical simulations of binary black hole (BH) coalescence, for both unequal masses and non-zero, non-precessing spins. We show that multipole moments up to and including l=4 are sufficient to accurately reproduce the final recoil velocity (within ~2%) and that only a few dominant modes contribute significantly to it (within ~5%). We describe how the relative amplitudes, and more importantly, the relative phases, of these few modes control the way in which the recoil builds up throughout the inspiral, merger, and ringdown phases. We also find that the numerical results can be reproduced by an ``effective Newtonian'' formula for the multipole moments obtained by replacing the radial separation in the Newtonian formulae with an effective radius computed from the numerical data. Beyond the merger, the numerical results are reproduced by a superposition of three Kerr quasi-normal modes (QNMs). Analytic formulae, obtained by expressin...

  17. Multipolar interference for non-reciprocal nonlinear generation

    Poutrina, Ekaterina; Urbas, Augustine

    2016-01-01

    We show that nonlinear multipolar interference allows achieving not only unidirectional, but also non-reciprocal nonlinear generation from a nanoelement, with the direction of the produced light decoupled from the direction of at least one of the excitation beams. Alternatively, it may allow inhibiting the specified nonlinear response in a nanoelement or in its periodic arrangement by reversing the direction of one of the pumps. These general phenomena exploit the fact that, contrary to the linear response case, nonlinear magneto-electric interference stems from a combination of additive and multiplicative processes and includes an interference between various terms within the electric and magnetic partial waves themselves. We demonstrate the introduced concept numerically using an example of a plasmonic dimer geometry with realistic material parameters. PMID:27126209

  18. Transition between viscous dipolar and inertial multipolar dynamos

    Oruba, Ludivine

    2014-01-01

    We show that the transition between steady dipolar and fluctuating multipolar dynamos is characterized by a three terms balance between the non-gradient parts of inertial, viscous and Coriolis forces. We derive from this equilibrium the sole parameter Ro E$^{-1/3} \\equiv$ Re E$^{2/3}$, which accurately describes the transition for a wide database of 132 fully three dimensional direct numerical simulations of spherical rotating dynamos (courtesy of U. Christensen). This transition can be equivalently described by Ro/l$^\\star_u$ (resp. Re l$^{\\star\\, 2}_u$), which correspond to the two terms balance between the non-gradient part of the Coriolis force and of inertial (resp. viscous) forces. An appropriate definition of the non-dimensional dissipation length scale l$^\\star_u$ (as introduced in Oruba and Dormy, 2014) provides a critical value of this parameter of order unity at the transition.

  19. Cytokinesis failure and successful multipolar mitoses drive aneuploidy in glioblastoma cells.

    Telentschak, Sergej; Soliwoda, Mark; Nohroudi, Klaus; Addicks, Klaus; Klinz, Franz-Josef

    2015-04-01

    Glioblastoma (GB) is the most frequent human brain tumor and is associated with a poor prognosis. Multipolar mitosis and spindles have occasionally been observed in cultured glioblastoma cells and in glioblastoma tissues, but their mode of origin and relevance have remained unclear. In the present study, we investigated a novel GB cell line (SGB4) exhibiting mitotic aberrations and established a functional link between cytokinesis failure, centrosome amplification, multipolar mitosis and aneuploidy in glioblastoma. Long-term live cell imaging showed that >3% of mitotic SGB4 cells underwent multipolar mitosis (tripolar>tetrapolar>pentapolar). A significant amount of daugther cells generated by multipolar mitosis were viable and completed several rounds of mitosis. Pedigree analysis of mitotic events revealed that in many cases a bipolar mitosis with failed cytokinesis occurred prior to a multipolar mitosis. Additionally, we observed that SGB4 cells were also able to undergo a bipolar mitosis after failed cytokinesis. Colchicine-induced mitotic arrest and metaphase spreads demonstrated that SGB4 cells had a modal chromosome number of 58 ranging from 23 to 170. Approximately 82% of SGB4 cells were hyperdiploid (47-57 chromosomes) or hypotriploid (58-68 chromosomes). In conclusion, SGB4 cells passed through multipolar cell divisions and generated viable progeny by reductive mitoses. Our results identified cytokinesis failure occurring before and after multipolar or bipolar mitoses as important mechanisms to generate chromosomal heterogeneity in glioblastoma cells. PMID:25625503

  20. Simulated multipolarized MAPSAR images to distinguish agricultural crops

    Wagner Fernando Silva

    2012-06-01

    Full Text Available Many researchers have shown the potential of Synthetic Aperture Radar (SAR images for agricultural applications, particularly for monitoring regions with limitations in terms of acquiring cloud free optical images. Recently, Brazil and Germany began a feasibility study on the construction of an orbital L-band SAR sensor referred to as MAPSAR (Multi-Application Purpose SAR. This sensor provides L-band images in three spatial resolutions and polarimetric, interferometric and stereoscopic capabilities. Thus, studies are needed to evaluate the potential of future MAPSAR images. The objective of this study was to evaluate multipolarized MAPSAR images simulated by the airborne SAR-R99B sensor to distinguish coffee, cotton and pasture fields in Brazil. Discrimination among crops was evaluated through graphical and cluster analysis of mean backscatter values, considering single, dual and triple polarizations. Planting row direction of coffee influenced the backscatter and was divided into two classes: parallel and perpendicular to the sensor look direction. Single polarizations had poor ability to discriminate the crops. The overall accuracies were less than 59 %, but the understanding of the microwave interaction with the crops could be explored. Combinations of two polarizations could differentiate various fields of crops, highlighting the combination VV-HV that reached 78 % overall accuracy. The use of three polarizations resulted in 85.4 % overall accuracy, indicating that the classes pasture and parallel coffee were fully discriminated from the other classes. These results confirmed the potential of multipolarized MAPSAR images to distinguish the studied crops and showed considerable improvement in the accuracy of the results when the number of polarizations was increased.

  1. Binary black hole merger in the extreme-mass-ratio limit: A multipolar analysis

    Building up on previous work, we present a new calculation of the gravitational wave emission generated during the transition from quasicircular inspiral to plunge, merger, and ringdown by a binary system of nonspinning black holes, of masses m1 and m2, in the extreme mass ratio limit, m1m21+m2)2. The relative dynamics of the system is computed without making any adiabatic approximation by using an effective one body (EOB) description, namely, by representing the binary by an effective particle of mass μ=m1m2/(m1+m2) moving in a (quasi-)Schwarzschild background of mass M=m1+m2 and submitted to an O(ν) 5PN-resummed analytical radiation reaction force, with ν=μ/M. The gravitational wave emission is calculated via a multipolar Regge-Wheeler-Zerilli-type perturbative approach (valid in the limit ν-2,10-3,10-4}, and we compute the multipolar waveform up to l=8. We estimate energy and angular momentum losses during the quasiuniversal and quasigeodesic part of the plunge phase and we analyze the structure of the ringdown. We calculate the gravitational recoil, or 'kick', imparted to the merger remnant by the gravitational wave emission and we emphasize the importance of higher multipoles to get a final value of the recoil v/(cν2)=0.0446. We finally show that there is an excellent fractional agreement (∼10-3) (even during the plunge) between the 5PN EOB analytically resummed radiation reaction flux and the numerically computed gravitational wave angular momentum flux. This is a further confirmation of the aptitude of the EOB formalism to accurately model extreme-mass-ratio inspirals, as needed for the future space-based LISA gravitational wave detector.

  2. Short exposure to paclitaxel induces multipolar spindle formation and aneuploidy through promotion of acentrosomal pole assembly

    2010-01-01

    Paclitaxel is a widely used microtubule drug and cancer medicine. Here we report that by short exposure to paclitaxel at a low dose, multipolar spindles were induced in mitotic cells without centrosome amplification. Both TPX2 depletion and Aurora-A overexpression antagonized the multipolarity. Live cell imaging showed that some paclitaxel-treated cells accomplished multipolar cell division and a portion of the daughter cells went on to the next round of mitosis. The surviving cells grew into clones with varied genome content. The results indicated that an aneuploidy population could be induced by short exposure to paclitaxel at a low dose, implicating potential side effects of paclitaxel.

  3. Multilevel Cortical Processing of Somatosensory Novelty: A Magnetoencephalography Study

    Naeije, Gilles; Vaulet, Thibaut; Wens, Vincent; Marty, Brice; Goldman, Serge; De Tiège, Xavier

    2016-01-01

    Using magnetoencephalography (MEG), this study investigates the spatio-temporal dynamics of the multilevel cortical processing of somatosensory change detection. Neuromagnetic signals of 16 healthy adult subjects (7 females and 9 males, mean age 29 ± 3 years) were recorded using whole-scalp-covering MEG while they underwent an oddball paradigm based on simple standard (right index fingertip tactile stimulation) and deviant (simultaneous right index fingertip and middle phalanx tactile stimulation) stimuli gathered into sequences to create and then deviate from stimulus patterns at multiple (local vs. global) levels of complexity. Five healthy adult subjects (3 females and 2 males, mean age 31, 6 ± 2 years) also underwent a similar oddball paradigm in which standard and deviant stimuli were flipped. Local deviations led to a somatosensory mismatch response peaking at 55–130 ms post-stimulus onset with a cortical generator located at the contralateral secondary somatosensory (cSII) cortex. The mismatch response was independent of the deviant stimuli physical characteristics. Global deviants led to a P300 response with cortical sources located bilaterally at temporo-parietal junction (TPJ) and supplementary motor area (SMA). The posterior parietal cortex (PPC) and the SMA were found to generate a contingent magnetic variation (CMV) attributed to top-down expectations. Amplitude of mismatch responses were modulated by top-down expectations and correlated with both the magnitude of the CMV and the P300 amplitude at the right TPJ. These results provide novel empirical evidence for a unified sensory novelty detection system in the human brain by linking detection of salient sensory stimuli in personal and extra-personal spaces to a common framework of multilevel cortical processing. PMID:27313523

  4. Multilevel cortical processing of somatosensory novelty: a magnetoencephalography study

    Gilles eNaeije

    2016-06-01

    Full Text Available Using magnetoencephalography (MEG, this study investigates the spatio-temporal dynamics of the multilevel cortical processing of somatosensory change detection. Neuromagnetic signals of sixteen healthy adult subjects (7 females and 9 males, mean age 29 +/-3 y were recorded using whole-scalp-covering MEG while they underwent an oddball paradigm based on simple standard (right index fingertip tactile stimulation and deviant (simultaneous right index fingertip and middle phalanx tactile stimulation stimuli gathered into sequences to create and then deviate from stimulus patterns at multiple (local versus global levels of complexity. Five healthy adult subjects (3 females and 2 males, mean age 31,6 +/-2 y also underwent a similar oddball paradigm in which standard and deviant stimuli were flipped.Local deviations led to a somatosensory mismatch response peaking at 55-130 ms post-stimulus onset with a cortical generator located at the contralateral secondary somatosensory cortex. The mismatch response was independent of the deviant stimuli physical characteristics. Global deviants led to a P300 response with cortical sources located bilaterally at temporo-parietal junction (TPJ and supplementary motor area (SMA. The posterior parietal cortex (PPC and the SMA were found to generate a contingent magnetic variation (CMV attributed to top-down expectations. Amplitude of mismatch responses were modulated by top-down expectations and correlated with both the magnitude of the CMV and the P300 amplitude at the right TPJ. These results provide novel empirical evidence for a unified sensory novelty detection system in the human brain by linking detection of salient sensory stimuli in personal and extra-personal spaces to a common framework of multilevel cortical processing.

  5. Functional characterisation of letter-specific responses in time, space and current polarity using magnetoencephalography.

    Gwilliams, L; Lewis, G A; Marantz, A

    2016-05-15

    Recent neurophysiological evidence suggests that a hierarchical neural network of low-to-high level processing subserves written language comprehension. While a considerable amount of research has identified distinct regions and stages of processing, the relations between them and to this hierarchical model remain unclear. Magnetoencephalography (MEG) is a technique frequently employed in such investigations; however, no studies have sought to test whether the conventional method of reconstructing currents at the source of the magnetic field is best suited for such across-subject designs. The present study details the results of three MEG experiments addressing these issues. Neuronal populations supporting responses to low-level orthographic properties were housed posteriorly near the primary visual cortex. More anterior regions along the fusiform gyrus encoded higher-level processes and became active ~80ms later. A functional localiser of these early letter-specific responses was developed for the production of functional regions of interest in future studies. Previously established response components were successfully grouped based on proximity to the localiser, which characterised location, latency and functional sensitivity. Unconventional anatomically constrained signed minimum norm estimates of MEG data were most sensitive to the primary experimental manipulation, suggesting that the conventional unsigned unconstrained method is sub-optimal for studying written word processing. PMID:26926792

  6. The spatial structure of the Russian economy and the multipolar world

    Valentina Lapo

    2012-01-01

    There have been several poles of development USA, Europe, and China are formatted in the world economy. How does the multipolar world economy influence the Russian region‘s development? How does the spatial structure of Russian economy develop under the multipolar world economy? The studies based on the main results of new economic geography and gravity theory concerning the spatial concentration of production, the core and periphery formation in the economy of countries and large regions. We...

  7. The Multiple Functions of T Stellate/Multipolar/Chopper Cells in the Ventral Cochlear Nucleus

    Oertel, Donata; Wright, Samantha; Cao, Xiao-Jie; Ferragamo, Michael; Bal, Ramazan

    2010-01-01

    Acoustic information is brought to the brain by auditory nerve fibers, all of which terminate in the cochlear nuclei, and is passed up the auditory pathway through the principal cells of the cochlear nuclei. A population of neurons variously known as T stellate, type I multipolar, planar multipolar, or chopper cells forms one of the major ascending auditory pathways through the brain stem. T Stellate cells are sharply tuned; as a population they encode the spectrum of sounds. In these neurons...

  8. Transverse multipolar light-matter couplings in evanescent waves

    Fernandez-Corbaton, Ivan; Bonod, Nicolas; Rockstuhl, Carsten

    2016-01-01

    We present an approach to study the interaction between matter and evanescent fields. The approach is based on the decomposition of evanescent plane waves into multipoles of well-defined angular momentum transverse to both decay and propagation directions. We use the approach to identify the origin of the recently observed directional coupling of emitters into guided modes, and of the opposite Zeeman state excitation of atoms near a fiber. We explain how to rigorously quantify both effects, and show that the directionality and the difference in excitation rates grow exponentially with the multipolar order of the light-matter interaction. We also use the approach to study and maximize the transverse torque exerted by an evanescent plane wave onto a given spherical absorbing particle. The maximum occurs at the quadrupolar order of the particle, and for a particular polarization of the plane wave. All the obtained physical insights can be traced back to the two main features of the decomposition of evanescent pl...

  9. Ion energy distribution function in a multipolar confinement plasma system

    Experimental results are presented on the ion distribution function measured in a multipolar confinement plasma system used for generation of low energy ion beam. The ion beam is produced in argon plasma at a pressure of about 10-4 mbar using dc discharges similar to so called DP machine. Plasma parameters in the source chamber were: electron density in the range 108 to 1010 cm-3 and electron temperature in the range 0.5 to 6.0 eV. The target chamber was used as a technological one in which plasma density ranges between zero and 107 cm-3 but electron temperature was similar to that in the source chamber. The ion energy distribution function was measured with two types of electrostatic analyzers, one with a diameter of 10 cm made of a mesh grid with 70% transparency and a plane collector, and the other one with a diameter of 8 mm made of two mesh grids both with 48% transparency. Energy distribution function of the ions in the target plasma has been measured versus plasma density, beam density and energy. (authors)

  10. Relationships between multipolarized radar backscatter and slash pine stand parameters

    Hussin, Yousif Ali; Hoffer, Roger M.

    1989-01-01

    Multipolarized L-band (24.5 cm) aircraft radar data was obtained for a primarily forested area in northern Florida. Based on the results of previous studies by Hoffer and Hussin (1989), a swath of medium incidence angle (35-25 deg) data was defined. Three groups of slash pine stands were located in the data: 4- to 17-year-old plantations, 18- to 48-year-old plantations, and 16- to 53-year-old natural stands. Stand data obtained from the forest-products companies operating in the area include age, tree height, diameter-at-breast height, basal area, volume (cords/acre), and density (trees/acre). Each of these stand parameters were compared to each of the four polarizations (HH, VV, VH, and HV) of the radar data for each group of stands. Statistically significant relationships were found between the radar backscatter and the forest stand parameters only for the 4- to 17-year-old slash pine plantation stands. In general, the cross-polarized radar backscatter was more highly correlated with the various stand parameters than the like-polarized backscatter, and the VV-polarized data were more highly correlated than the HH-polarized data.

  11. 抑郁症患者执行控制脑皮质网络损害的脑磁源性研究%The primary explore of the damage of the executive control network in major depressive disorder:a dynamic causal model on magnetoencephalography

    花玲玲; 姚志剑; 汤浩; 阎锐; 陈建淮; 韩颖琳; 卢青

    2015-01-01

    Objective To investigate the interconnection of the executive control network in major depressive disorder when they recognized the sad facial stimuli,and to discuss the aberrant mechanism of emotion processing.Methods Twenty major depressive patients and 20 well-matched healthy volunteers participated in the experiment.The brain actions of all subjects were recorded by the magnetoencephalography (MEG) when they were required to distinguish the emotion face.Based on prior knowledge,the interested brain area consisted of the primary visual cortex (V1),the orbitofrontal cortex(OFC),the dorsolateral prefrontal cortex (DLPFC),the anterior cingulated cortex (ACC).Then constructing three competing models to select an optimal model by the method of dynamic causal model(DCM),finally the differences of the effective connections of the optimal model between the depressed patients and healthy controls were analyzed.Results According to the results of Bayesian model selection (BMS),model 1 had the most exceedance probability of 0.80 with the features that there were bidirectional modulatory connections between the OFC,ACC and DLPFC.Given the best model,the parameters of effective connectivity of the optimal model were extracted,and then two-sample t-test over the model 1 was adopted.The modulatory effective connectivity from the OFC to the DLPFC in both hemisphere(t=-2.73,P=0.0096;t=-3.01,P=0.0046) and the OFC to the ACC (t=-2.93,P=0.0057) in the left hemisphere were significantly reduced in MDD.Conclusion There exists abnormal function of executive control network in depressed patients,the decreased effective connections between the OFC and the DLPFC,as well as the OFC and the ACC,may have correlation with the negative%目的 探究抑郁症患者在识别悲伤表情时执行控制网络中脑区的相互作用机制,并以此探讨抑郁症患者悲伤情绪处理异常的可能机制.方法 利用脑磁图(MEG)检测20例抑郁症患者及20例相匹配的健康对照者

  12. Multipolar Electrostatic Energy Prediction for all 20 Natural Amino Acids Using Kriging Machine Learning.

    Fletcher, Timothy L; Popelier, Paul L A

    2016-06-14

    A machine learning method called kriging is applied to the set of all 20 naturally occurring amino acids. Kriging models are built that predict electrostatic multipole moments for all topological atoms in any amino acid based on molecular geometry only. These models then predict molecular electrostatic interaction energies. On the basis of 200 unseen test geometries for each amino acid, no amino acid shows a mean prediction error above 5.3 kJ mol(-1), while the lowest error observed is 2.8 kJ mol(-1). The mean error across the entire set is only 4.2 kJ mol(-1) (or 1 kcal mol(-1)). Charged systems are created by protonating or deprotonating selected amino acids, and these show no significant deviation in prediction error over their neutral counterparts. Similarly, the proposed methodology can also handle amino acids with aromatic side chains, without the need for modification. Thus, we present a generic method capable of accurately capturing multipolar polarizable electrostatics in amino acids. PMID:27224739

  13. Assessment of cortical dysfunction in human strabismic amblyopia using magnetoencephalography (MEG)

    The aim of this study was to use the technique of magnetoencephalography (MEG) to determine the effects of strabismic amblyopia on the processing of spatial information within the occipital cortex of humans. We recorded evoked magnetic responses to the onset of a chromatic (red/green) sinusoidal grating of periodicity 0.5-4.0 c deg-1 using a 19-channel SQUID-based neuromagnetometer. Evoked responses were recorded monocularly on six amblyopes and six normally-sighted controls, the stimuli being positioned near the fovea in the lower right visual field of each observer. For comparison, the spatial contrast sensitivity function (CSF) for the detection of chromatic gratings was measured for one amblyope and one control using a two alternate forced-choice psychophysical procedure. We chose red/green sinusoids as our stimuli because they evoke strong magnetic responses from the occipital cortex in adult humans (Fylan, Holliday, Singh, Anderson and Harding. (1997). Neuroimage, 6, 47-57). Magnetic field strength was plotted as a function of stimulus spatial frequency for each eye of each subject. Interocular differences were only evident within the amblyopic group: for stimuli of 1-2 c deg-1, the evoked responses had significantly longer latencies and reduced amplitudes through the amblyopic eye (P<0.05). Importantly, the extent of the deficit was uncorrelated with either Snellen acuity or contrast sensitivity. Localization of the evoked responses was performed using a single equivalent current dipole model. Source localizations, for both normal and amblyopic subjects, were consistent with neural activity at the occipital pole near the V1/V2 border. We conclude that MEG is sensitive to the deficit in cortical processing associated with human amblyopia, and can be used to make quantitative neurophysiological measurements. The nature of the cortical deficit is discussed. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  14. Observational Characteristics of Radio Emission Related to Multi-polar Magnetic Configuration

    Min Wang; Rui-Xiang Xie; Chun Xu; Shuo-Biao Shi; Yi-Hua Yan

    2005-01-01

    We present a large complex radio burst and its associated fast time structures observed on 2001 April 10 in the frequency range of 0.65-7.6 GHz. The NoRH radio image observation shows very complex radio source structures which include preexisting, newly emerging, submerging/cancelling polarities and a biposuggests that the radio burst is generated from a very complicated loop structure.According to the spectral and image observations, we assume that the beginning connection structure. A composite of radio continuum and fast time structures is contained in this flare. The various fast radio emission phenomena include normal and reverse drifting type Ⅲ bursts, and slowly drifting and no-drift structures.ture, which is an important source of the various types of fast time structures.The two-loop reconnection model can lead simultaneously to electron acceleration and corona heating. We have also analyzed the behaviors of coronal magnetic polarities and the emission processes of different types radio emission qualitatively.Interactions of a bipolar or multi-polar loop are consistent with our observational results. Our observations favor the magnetic reconnection configurations of the lar).

  15. FMRP regulates multipolar to bipolar transition affecting neuronal migration and cortical circuitry.

    La Fata, Giorgio; Gärtner, Annette; Domínguez-Iturza, Nuria; Dresselaers, Tom; Dawitz, Julia; Poorthuis, Rogier B; Averna, Michele; Himmelreich, Uwe; Meredith, Rhiannon M; Achsel, Tilmann; Dotti, Carlos G; Bagni, Claudia

    2014-12-01

    Deficiencies in fragile X mental retardation protein (FMRP) are the most common cause of inherited intellectual disability, fragile X syndrome (FXS), with symptoms manifesting during infancy and early childhood. Using a mouse model for FXS, we found that Fmrp regulates the positioning of neurons in the cortical plate during embryonic development, affecting their multipolar-to-bipolar transition (MBT). We identified N-cadherin, which is crucial for MBT, as an Fmrp-regulated target in embryonic brain. Furthermore, spontaneous network activity and high-resolution brain imaging revealed defects in the establishment of neuronal networks at very early developmental stages, further confirmed by an unbalanced excitatory and inhibitory network. Finally, reintroduction of Fmrp or N-cadherin in the embryo normalized early postnatal neuron activity. Our findings highlight the critical role of Fmrp in the developing cerebral cortex and might explain some of the clinical features observed in patients with FXS, such as alterations in synaptic communication and neuronal network connectivity. PMID:25402856

  16. The Shaping of the Multipolar Pre-Planetary Nebula CRL 618 by Multi-directional Bullets

    Huang, Po-Sheng; Moraghan, Anthony; Smith, Michael

    2016-01-01

    In order to understand the formation of the multipolar structures of the pre-planetary nebula (PPN) CRL 618, we perform 3D simulations using a multi-directional bullet model. The optical lobes of CRL 618 and fast molecular outflows at the tips of the lobes have been found to have similar expansion ages of ~ 100 yr. Additional fast molecular outflows were found near the source along the outflow axes with ages of ~ 45 yr, suggesting a second episode of bullet ejections. Thus, in our simulations, two episodes of bullet ejections are assumed. The shaping process is simulated using the ZEUS-3D hydrodynamics code that includes molecular and atomic cooling. In addition, molecular chemistry is also included to calculate the CO intensity maps. Our results show the following: (1) Multi-epoch bullets interacting with the toroidal dense core can produce the collimated multiple lobes as seen in CRL 618. The total mass of the bullets is ~ 0.034 solar mass, consistent with the observed high-velocity CO emission in fast mole...

  17. Post fall-back evolution of multipolar magnetic fields and radio pulsar activation

    Igoshev, A P; Popov, S B

    2016-01-01

    It has long been unclear if the small-scale magnetic structures on the neutron star (NS) surface could survive the fall-back episode. The study of the Hall cascade (Cumming, Arras and Zweibel 2004; Wareing and Hollerbach 2009) hinted that energy in small scales structures should dissipate on short timescales. Our new 2D magneto-thermal simulations suggest the opposite. For the first $\\sim$10 kyrs after the fall-back episode with accreted mass $10^{-3} M_\\odot$, the observed NS magnetic field appears dipolar, which is insensitive to the initial magnetic topology. In framework of the Ruderman & Sutherland (1975) vacuum gap model during this interval, non-thermal radiation is strongly suppressed. After this time the initial (i.e. multipolar) structure begins to re-emerge through the NS crust. We distinguish three evolutionary epochs for the re-emergence process: the growth of internal toroidal field, the advection of buried poloidal field, and slow Ohmic diffusion. The efficiency of the first two stages can ...

  18. Organizing for Spaces and Dynamics of Multipolar Learning in Multinational Corporations

    Hull Kristensen, Peer; Lotz, Maja

    Limited research has been conducted on how MNCs organize conditions and spaces for recursive learning to facilitate the practice of innovation across dispersed units as well as how organizational members at all levels may become involved in innovations through the engagement in ongoing multipolar...... learning dynamics. Based on longitudinal case studies in two MNCs this paper contributes with insights into how spaces and dynamics of multipolar learning are organized and governed across dispersed MNC units at the micro level of everyday work practices. The paper shows that it is possible to organize...... spaces and dynamics that can organize recursiveness and continuity in multipolar learning by way of experimentation with new coordination components and governance architectures. Against the previous literature, however, it becomes evident that these are not the outcome of spontaneous interactions in a...

  19. Differential brain activity states during the perception and nonperception of illusory motion as revealed by magnetoencephalography

    Crowe, David A.; Leuthold, Arthur C.; Georgopoulos, Apostolos P.

    2010-01-01

    We studied visual perception using an annular random-dot motion stimulus called the racetrack. We recorded neural activity using magnetoencephalography while subjects viewed variants of this stimulus that contained no inherent motion or various degrees of embedded motion. Subjects reported seeing rotary motion during viewing of all stimuli. We found that, in the absence of any motion signals, patterns of brain activity differed between states of motion perception and nonperception. Furthermor...

  20. Age-related sex differences in language lateralization: a magnetoencephalography (MEG) study in children

    Yu, Vickie Y.; MacDonald, Matt J.; Oh, Anna; Hua, Gordon N.; De Nil, Luc F.; Elizabeth W Pang

    2014-01-01

    It is well supported by behavioral and neuroimaging studies that typical language function is lateralized to the left hemisphere in the adult brain and this laterality is less well defined in children. The behavioral literature suggests there maybe be sex differences in language development but this has not been examined systematically using neuroimaging. In this study, magnetoencephalography (MEG) was used to investigate the spatiotemporal patterns of language lateralization as a function of...

  1. Magnetoencephalography study of brain dynamics in young children born extremely preterm

    Cepeda, I.L.; Grunau, R.E.; Weinberg, H.; Herdman, A.T.; Cheung, T; Liotti, M.; Amir, A; Synnes, A.; Whitfield, M

    2007-01-01

    Magnetoencephalography (MEG) was recorded while 5–7 year-old children were performing a visual–spatial memory recognition task. Full-term children showed greater gamma-band (30–50 Hz) amplitude in the right temporal region during the task, than children who were born extremely preterm. These results may represent altered brain processing in extremely preterm children who escape major impairment.

  2. A study of the multipolar composition of the electrofission cross section of 237Np

    The electrofission cross section for 237Np was measured over the energy range from 0,6 to 60,0 MeV. The multipolar composition of this cross section was investigated using the virtual photons formalism with three different techniques of analysis: unfolding and two versions of multiple parameter regression. (A.C.A.S.)

  3. Connexin 43 controls the multipolar phase of neuronal migration to the cerebral cortex.

    Liu, Xiuxin; Sun, Lin; Torii, Masaaki; Rakic, Pasko

    2012-05-22

    The prospective pyramidal neurons, migrating from the proliferative ventricular zone to the overlaying cortical plate, assume multipolar morphology while passing through the transient subventricular zone. Here, we show that this morphogenetic transformation, from the bipolar to the mutipolar and then back to bipolar again, is associated with expression of connexin 43 (Cx43) and, that knockdown of Cx43 retards, whereas its overexpression enhances, this morphogenetic process. In addition, we have observed that knockdown of Cx43 reduces expression of p27, whereas overexpression of p27 rescues the effect of Cx43 knockdown in the multipolar neurons. Furthermore, functional gap junction/hemichannel domain, and the C-terminal domain of Cx43, independently enhance the expression of p27 and promote the morphological transformation and migration of the multipolar neurons in the SVZ/IZ. Collectively, these results indicate that Cx43 regulates the passage of migrating neurons through their multipolar stage via p27 signaling and that interference with this process, by either genetic and/or environmental factors, may cause cortical malformations. PMID:22566616

  4. Evidence of multipolar response of Bacteriorhodopsin by noncollinear second harmonic generation.

    Bovino, F A; Larciprete, M C; Sibilia, C; Váró, G; Gergely, C

    2012-06-18

    Noncollinear second harmonic generation from a Bacteriorhodopsin (BR) oriented multilayer film was systematically investigated by varying the polarization state of both fundamental beams. Both experimental results and theoretical simulations, show that the resulting polarization mapping is an useful tool to put in evidence the optical chirality of the investigated film as well as the corresponding multipolar contributions to the nonlinear. PMID:22714524

  5. Multipolar radiofrequency ablation using internally cooled electrodes in ex vivo bovine liver: Correlation between volume of coagulation and amount of applied energy

    Purpose: To evaluate the relationship between applied energy and volume of coagulation induced by multipolar radiofrequency (RF) ablation. Methods and materials: Multipolar RF ablations (n = 80) were performed in ex vivo bovine liver. Three bipolar applicators with two electrodes located on each applicator shaft were placed in a triangular array. The power-output (75–225 W) and the distance between the different applicators (2, 3, 4, 5 cm) were systematically varied. The volume of confluent white coagulation and the amount of applied energy were assessed. Based on our experimental data the relationship between the volume of coagulation and applied energy was assessed by nonlinear regression analysis. The variability explained by the model was determined by the parameter r2. Results: The volume of coagulation increases with higher amounts of applied energy. The maximum amount of energy was applied at a power-output of 75 W and an applicator distance of 5 cm. The corresponding maximum volume of coagulation was 324 cm3 and required an application of 453 kJ. The relationship between amount of applied energy (E) and volume (V) of coagulation can be described by the function, V = 4.39E0.7 (r2 = 0.88). By approximation the volume of coagulation can be calculated by the linear function V = 0.61E + 40.7 (r2 = 0.87). Conclusion: Ex vivo the relationship between volume of coagulation and amount of applied energy can be described by mathematical modeling. The amount of applied energy correlates to the volume of coagulation and may be a useful parameter to monitor multipolar RF ablation.

  6. Wnt signaling regulates multipolar-to-bipolar transition of migrating neurons in the cerebral cortex.

    Boitard, Michael; Bocchi, Riccardo; Egervari, Kristof; Petrenko, Volodymyr; Viale, Beatrice; Gremaud, Stéphane; Zgraggen, Eloisa; Salmon, Patrick; Kiss, Jozsef Z

    2015-03-01

    The precise timing of pyramidal cell migration from the ventricular germinal zone to the cortical plate is essential for establishing cortical layers, and migration errors can lead to neurodevelopmental disorders underlying psychiatric and neurological diseases. Here, we report that Wnt canonical as well as non-canonical signaling is active in pyramidal precursors during radial migration. We demonstrate using constitutive and conditional genetic strategies that transient downregulation of canonical Wnt/β-catenin signaling during the multipolar stage plays a critical role in polarizing and orienting cells for radial migration. In addition, we show that reduced canonical Wnt signaling is triggered cell autonomously by time-dependent expression of Wnt5A and activation of non-canonical signaling. We identify ephrin-B1 as a canonical Wnt-signaling-regulated target in control of the multipolar-to-bipolar switch. These findings highlight the critical role of Wnt signaling activity in neuronal positioning during cortical development. PMID:25732825

  7. The emerging multi-polar world and China's grand game

    Gupta, Rajan [Los Alamos National Laboratory

    2011-01-19

    This talk outlines a scenario describing an emerging multipolar world that is aligned with geographical regions. The stability and security of this multipolar world is examined with respect to demographics, trade (economics), resource constraints, and development. In particular I focus on Asia which has two large countries, China and India, competing for resources and markets and examine the emerging regional relations, opportunities and threats. These relationships must overcome many hurdles - the Subcontinent is in a weak position politically and strategically and faces many threats, and China's growing power could help stabilize it or create new threats. Since the fate of 1.5 billion (2.4 billion by 2050) people depends on how the Subcontinent evolves, this talk is meant to initiates a discussion of what China and India can do to help the region develop and stabilize.

  8. Multipolare Rhetorik vs. unilaterale Ambitionen : die Grenzen russischer Außenpolitik

    Meister, Stefan

    2009-01-01

    "Das Eintreten für eine multipolare Weltordnung und gegen einen US-amerikanischen Unilateralismus ist eine Konstante russischer Außenpolitik seit dem Ende des Ost-West-Konflikts. Dabei gelten die Vereinten Nationen als die wichtigste internationale Organisation, um dieses Ziel zu erreichen. Jedoch führt Russlands Bekenntnis zu einer multipolaren Weltordnung nicht zu der Schlussfolgerung, multilateral zu handeln. Im Gegenteil, Moskau verfolgt eine klare Interessenpolitik, die weniger auf Konse...

  9. Analysis and Planning of 802.11n MIMO wireless network using Multi-Polarized Antenna

    Wu, Haotian; Nayyeri, Atefeh Dehghan

    2011-01-01

    MIMO (Multi Input Multi Output) technology is widely used in current wireless communication standard. Compared with SISO (Single Input Single Output) technology, MIMO can provide higher data rate and better communication quality. This thesis mainly focus on improving the communication quality of wireless local area network(WLAN) using wireless communication device with MIMO technology and Multi-polarized antenna. Meanwhile, an WLAN indoor plan example will be studied. The original WLAN indoor...

  10. Image-guided multipolar radiofrequency ablation of liver tumours: initial clinical results

    Terraz, Sylvain; Constantin, Christophe; Becker, Christoph D. [Geneva University Hospital, Department of Radiology, Geneva 14 (Switzerland); Majno, Pietro Edoardo; Mentha, Gilles [Geneva University Hospital, Department of Surgery, Geneva 14 (Switzerland); Spahr, Laurent [Geneva University Hospital, Department of Gastroenterology, Geneva 14 (Switzerland)

    2007-09-15

    The local effectiveness and clinical usefulness of multipolar radiofrequency (RF) ablation of liver tumours was evaluated. Sixty-eight image-guided RF sessions were performed using a multipolar device with bipolar electrodes in 53 patients. There were 45 hepatocellular carcinomas (HCC) and 42 metastases with a diameter {<=}3 cm (n = 55), 3.1-5 cm (n = 29) and >5 cm (n = 3); 26 nodules were within 5 mm from large vessels. Local effectiveness and complications were evaluated after RF procedures. Mean follow-up was 17 {+-} 10 months. Recurrence and survival rates were analysed by the Kaplan-Meier method. The primary and secondary technical effectiveness rate was 82% and 95%, respectively. The major and minor complication rate was 2.9%, respectively. The local tumour progression at 1- and 2-years was 5% and 9% for HCC nodules and 17% and 31% for metastases, respectively; four of 26 nodules (15%) close to vessels showed local progression. The survival at 1 year and 2 years was 97% and 90% for HCC and 84% and 68% for metastases, respectively. Multipolar RF technique creates ablation zones of adequate size and tailored shape and is effective to treat most liver tumours, including those close to major hepatic vessels. (orig.)

  11. RP58 Regulates the Multipolar-Bipolar Transition of Newborn Neurons in the Developing Cerebral Cortex

    Chiaki Ohtaka-Maruyama

    2013-02-01

    Full Text Available Accumulating evidence suggests that many brain diseases are associated with defects in neuronal migration, suggesting that this step of neurogenesis is critical for brain organization. However, the molecular mechanisms underlying neuronal migration remain largely unknown. Here, we identified the zinc-finger transcriptional repressor RP58 as a key regulator of neuronal migration via multipolar-to-bipolar transition. RP58−/− neurons exhibited severe defects in the formation of leading processes and never shifted to the locomotion mode. Cre-mediated deletion of RP58 using in utero electroporation in RP58flox/flox mice revealed that RP58 functions in cell-autonomous multipolar-to-bipolar transition, independent of cell-cycle exit. Finally, we found that RP58 represses Ngn2 transcription to regulate the Ngn2-Rnd2 pathway; Ngn2 knockdown rescued migration defects of the RP58−/− neurons. Our findings highlight the critical role of RP58 in multipolar-to-bipolar transition via suppression of the Ngn2-Rnd2 pathway in the developing cerebral cortex.

  12. POWER-SHIFTS IN THE GLOBAL ECONOMY. TRANSITION TOWARDS A MULTIPOLAR WORLD ORDER

    Ion IGNAT

    2013-12-01

    Full Text Available The paper aims to analyze the new realities and trends related to the new polarity of the global economy, and thus the reconfiguration of global power centers, a process characterized by two simultaneous trends: the rise of new powers and the relative decline of traditional powers. At the beginning of 21st century, global power is suffering two major changes: on the one hand it manifests a transition from West to East, from Atlantic to the Asia-Pacific, and on the other hand, a diffusion from state to non-state actors. Current global economic power has a multipolar distribution, shared between the United States, European Union, Japan and BRICs, with no balance of power between these poles, opposed by the strong ambition of rising countries, China especially, China that rivals the traditional powers represented by the developed countries. The evolution of the main macroeconomic indicators given by the most important global organizations, shows a gradual transition towards a multipolar world. Therefore, the United States is and will remain for a long period of time the global economic leader. However, as China, India and Brazil are growing rapidly, and Russia is looking for lost status, the world is becoming multipolar.

  13. Mapping function in the human brain with magnetoencephalography, anatomical magnetic resonance imaging, and functional magnetic resonance imaging.

    George, J S; Aine, C J; Mosher, J C; Schmidt, D M; Ranken, D M; Schlitt, H A; Wood, C C; Lewine, J D; Sanders, J A; Belliveau, J W

    1995-09-01

    Integrated analyses of human anatomical and functional measurements offer a powerful paradigm for human brain mapping. Magnetoencephalography (MEG) and EEG provide excellent temporal resolution of neural population dynamics as well as capabilities for source localization. Anatomical magnetic resonance imaging (MRI) provides excellent spatial resolution of head and brain anatomy, whereas functional MRI (fMRI) techniques provide an alternative measure of neural activation based on associated hemodynamic changes. These methodologies constrain and complement each other and can thereby improve our interpretation of functional neural organization. We have developed a number of computational tools and techniques for the visualization, comparison, and integrated analysis of multiple neuroimaging techniques. Construction of geometric anatomical models from volumetric MRI data allows improved models of the head volume conductor and can provide powerful constraints for neural electromagnetic source modeling. These approaches, coupled to enhanced algorithmic strategies for the inverse problem, can significantly enhance the accuracy of source-localization procedures. We have begun to apply these techniques for studies of the functional organization of the human visual system. Such studies have demonstrated multiple, functionally distinct visual areas that can be resolved on the basis of their locations, temporal dynamics, and differential sensitivity to stimulus parameters. Our studies have also produced evidence of internal retinotopic organization in both striate and extrastriate visual areas but have disclosed organizational departures from classical models. Comparative studies of MEG and fMRI suggest a reasonable but imperfect correlation between electrophysiological and hemodynamic responses. We have demonstrated a method for the integrated analysis of fMRI and MEG, and we outline strategies for improvement of these methods. By combining multiple measurement techniques, we

  14. Epistemics for Learning Disabilities: Contributions from Magnetoencephalography, a Functional Neuroimaging Tool

    VÍCTOR SANTIUSTE-BERMEJO

    2008-01-01

    Full Text Available The syndrome known as Learning Disabilities (LD was described by S. Kirk in 1963. From that point on, institutions from the US, Canada and Spain have engaged in refining the concept and classification of LDs. The Complutense University in Spain, has proposed a descriptive and all-embracing definition, and has studied the different manifestations of LD, pursuing the description of biological markers and neurological features of LD’s main expressions: dyslexia, dyscalculia, dysorthographia, Attention Deficit and Hyperactivity Disorder –ADHD, and so forth. Findings in LD using functional neuroimaging techniques, namely Magnetoencephalography (MEG, are described. MEG is a non-invasive technique, which records magnetic fields naturally generated by the brain and their spatial distribution. It allows simultaneous functional and structural information. MEG is therefore used in the study of primary and superior cognitive functions, in surveillance of patterns of normal cognitive function and those specific to the different LD clinical manifestations.

  15. Denoising and Frequency Analysis of Noninvasive Magnetoencephalography Sensor Signals for Functional Brain Mapping

    Ukil, A

    2015-01-01

    Magnetoencephalography (MEG) is an important noninvasive, nonhazardous technology for functional brain mapping, measuring the magnetic fields due to the intracellular neuronal current flow in the brain. However, most often, the inherent level of noise in the MEG sensor data collection process is large enough to obscure the signal(s) of interest. In this paper, a denoising technique based on the wavelet transform and the multiresolution signal decomposition technique along with thresholding is presented, substantiated by application results. Thereafter, different frequency analysis are performed on the denoised MEG signals to identify the major frequencies of the brain oscillations present in the denoised signals. Time-frequency plots (spectrograms) of the denoised signals are also provided.

  16. rtMEG: A Real-Time Software Interface for Magnetoencephalography

    Sudre, Gustavo; Parkkonen, Lauri; Bock, Elizabeth; Baillet, Sylvain; Wang, Wei; Weber, Douglas J.

    2011-01-01

    To date, the majority of studies using magnetoencephalography (MEG) rely on off-line analysis of the spatiotemporal properties of brain activity. Real-time MEG feedback could potentially benefit multiple areas of basic and clinical research: brain-machine interfaces, neurofeedback rehabilitation of stroke and spinal cord injury, and new adaptive paradigm designs, among others. We have developed a software interface to stream MEG signals in real time from the 306-channel Elekta Neuromag MEG system to an external workstation. The signals can be accessed with a minimal delay (≤45 ms) when data are sampled at 1000 Hz, which is sufficient for most real-time studies. We also show here that real-time source imaging is possible by demonstrating real-time monitoring and feedback of alpha-band power fluctuations over parieto-occipital and frontal areas. The interface is made available to the academic community as an open-source resource. PMID:21687573

  17. Role of higher-multipolarity deformations in the potential energy of heaviest nuclei

    Potential energy of the superheavy nucleus 284114 is analyzed in a 6-dimensional deformation space. This space includes two quadrupole, three hexadecapole and one multipolarity-6 deformation parameter. The energy is minimized simultaneously in all 6 degrees of freedom. The analysis is done within a macroscopic-microscopic approach. As in the studies of other superheavy nuclei, the result is found to be very individual for a given nucleus. A more general feature is a small effect of one (γ4) of the hexadecapole deformation parameters on the energy of the nucleus. (author)

  18. Multipolar third-harmonic generation driven by optically-induced magnetic resonances

    Smirnova, Daria A; Smirnov, Lev A; Kivshar, Yuri S

    2016-01-01

    We analyze the third-harmonic generation from high-index dielectric nanoparticles and discuss the basic features and multipolar nature of the parametrically generated electromagnetic fields near the Mie-type optical resonances in silicon particles. By combining both analytical and numerical methods, we study the nonlinear scattering from simple nanoparticle geometries such as spheres and disks driven by the magnetic dipole resonance. We reveal the approaches for manipulating and directing the resonantly enhanced nonlinear emission with subwavelength all-dielectric structures that can be of a particular interest for a design of nonlinear optical antennas and engineering the magnetic optical nonlinear response at nanoscale.

  19. Role of the multipolar black-body radiation shifts in the atomic clocks at the 10-18 uncertainty level

    B K Sahoo

    2014-08-01

    We present here an overview of the role of the multipolar black-body radiation (BBR) shifts in the single ion atomic clocks to appraise the anticipated 10-18 uncertainty level. With an attempt to use the advanced technologies for reducing the instrumental uncertainties at the unprecedented low, it is essential to investigate contributions from the higher-order systematics to achieve the ambitious goal of securing the most precise clock frequency standard. In this context, we have analysed contributions to the BBR shifts from the multipolar polarizabilities in a few ion clocks.

  20. Dependence of the probabilities of the electric-multipole electron transitions in W24+ on multipolarity

    Usually it is accepted that the probabilities of the electric-multipole electron transitions are rapidly decreasing functions of their multipolarity. Therefore while calculating the probabilities of electronic transitions between the configurations of certain chosen parities, it seems sufficient to take into account the first nonzero term, i.e., to consider the electron transitions of lowest multipolarity permitted by the exact selection rules. This paper aims at verifying this assumption on the example of electric-octupole transitions in W24+ ion. For this purpose the large-scale multiconfiguration Hartree-Fock and Dirac-Fock calculations have been performed for the configurations [Kr]4d104f4 and [Kr]4d104f35s energy levels of W24+ ion. The relativistic corrections were taken into account in the quasirelativistic Breit-Pauli and fully relativistic Breit (taking into account QED effects) approximations. The role of correlation, relativistic, and QED corrections is discussed. Line strengths, oscillator strengths, and transition probabilities in Coulomb and Babushkin gauges are presented for E1 and E3 transitions among these levels.

  1. An analysis of the electromagnetic field in multi-polar linear induction system

    In this paper a new method for determination of the electromagnetic field vectors in a multi-polar linear induction system (LIS) is described. The analysis of the electromagnetic field has been done by four dimensional electromagnetic potentials in conjunction with theory of the magnetic loops . The electromagnetic field vectors are determined in the Minkovski's space as elements of the Maxwell's tensor. The results obtained are compared with those got from the analysis made by the finite elements method (FEM).With the method represented in this paper one can determine the electromagnetic field vectors in the multi-polar linear induction system using four-dimensional potential. A priority of this method is the obtaining of analytical results for the electromagnetic field vectors. These results are also valid for linear media. The dependencies are valid also at high speeds of movement. The results of the investigated linear induction system are comparable to those got by the finite elements method. The investigations may be continued in the determination of other characteristics such as drag force, levitation force, etc. The method proposed in this paper for an analysis of linear induction system can be used for optimization calculations. (Author)

  2. Wnt Signaling Regulates Multipolar-to-Bipolar Transition of Migrating Neurons in the Cerebral Cortex

    Michael Boitard

    2015-03-01

    Full Text Available The precise timing of pyramidal cell migration from the ventricular germinal zone to the cortical plate is essential for establishing cortical layers, and migration errors can lead to neurodevelopmental disorders underlying psychiatric and neurological diseases. Here, we report that Wnt canonical as well as non-canonical signaling is active in pyramidal precursors during radial migration. We demonstrate using constitutive and conditional genetic strategies that transient downregulation of canonical Wnt/β-catenin signaling during the multipolar stage plays a critical role in polarizing and orienting cells for radial migration. In addition, we show that reduced canonical Wnt signaling is triggered cell autonomously by time-dependent expression of Wnt5A and activation of non-canonical signaling. We identify ephrin-B1 as a canonical Wnt-signaling-regulated target in control of the multipolar-to-bipolar switch. These findings highlight the critical role of Wnt signaling activity in neuronal positioning during cortical development.

  3. Properties of liquid water from a systematic refinement of a high-rank multipolar electrostatic potential

    Shaik, Majeed S.; Liem, Steven Y.; Popelier, Paul L. A.

    2010-05-01

    We build on previous work [S. Y. Liem and P. L. A. Popelier, J. Chem. Theory Comput. 4, 353 (2008)], where for the first time, a high-rank multipolar electrostatic potential was used in molecular dynamics simulations of liquid water at a wide range of pressures and temperatures, and using a multipolar Ewald summation. Water is represented as a rigid body, with atomic multipole moments defined by quantum chemical topology partitioning its gas phase electron density. The effect of the level of theory on the local structure of liquid water is systematically addressed. Values for Lennard-Jones (LJ) parameters are optimized, for both oxygen and hydrogen atoms, against bulk properties. The best LJ parameters were then used in a set of simulations at 30 different temperatures (1 atm) and another set at 11 different pressures (at 298 K). Inclusion of the hydrogen LJ parameters significantly increases the self-diffusion coefficient. The behavior of bulk properties was studied and the local water structure analyzed by both radial and spatial distribution functions. Comparisons with familiar point-charge potentials, such as TIP3P, TIP4P, TIP5P, and simple point charge, show the benefits of multipole moments.

  4. Multi-polar resistance switching and memory effect in copper phthalocyanine junctions

    Copper phthalocyanine junctions, fabricated by magnetron sputtering and evaporating methods, show multi-polar (unipolar and bipolar) resistance switching and the memory effect. The multi-polar resistance switching has not been observed simultaneously in one organic material before. With both electrodes being cobalt, the unipolar resistance switching is universal. The high resistance state is switched to the low resistance state when the bias reaches the set voltage. Generally, the set voltage increases with the thickness of copper phthalocyanine and decreases with increasing dwell time of bias. Moreover, the low resistance state could be switched to the high resistance state by absorbing the phonon energy. The stability of the low resistance state could be tuned by different electrodes. In Au/copper phthalocyanine/Co system, the low resistance state is far more stable, and the bipolar resistance switching is found. Temperature dependence of electrical transport measurements demonstrates that there are no obvious differences in the electrical transport mechanism before and after the resistance switching. They fit quite well with Mott variable range hopping theory. The effect of Al2O3 on the resistance switching is excluded by control experiments. The holes trapping and detrapping in copper phthalocyanine layer are responsible for the resistance switching, and the interfacial effect between electrodes and copper phthalocyanine layer affects the memory effect. (interdisciplinary physics and related areas of science and technology)

  5. Multipolar electromagnetic fields around neutron stars: exact vacuum solutions and related properties

    Petri, Jerome

    2015-01-01

    The magnetic field topology in the surrounding of neutron stars is one of the key questions in pulsar magnetospheric physics. A very extensive literature exists about the assumption of a dipolar magnetic field but very little progress has been made in attempts to include multipolar components in a self-consistent way. In this paper, we study the effect of multipolar electromagnetic fields anchored in the star. We give exact analytical solutions in closed form for any order $l$ and apply them to the retarded point quadrupole ($l=2$), hexapole ($l=3$) and octopole ($l=4$), a generalization of the retarded point dipole ($l=1$). We also compare the Poynting flux from each multipole and show that the spin down luminosity depends on the ratio $R/r_{\\rm L}$, $R$ being the neutron star radius and $r_{\\rm L}$ the light-cylinder radius. Therefore the braking index also depends on $R/r_{\\rm L}$. As such multipole fields possess very different topology, most importantly smaller length scales compared to the dipolar field...

  6. When the genome plays dice: circumvention of the spindle assembly checkpoint and near-random chromosome segregation in multipolar cancer cell mitoses.

    David Gisselsson

    Full Text Available BACKGROUND: Normal cell division is coordinated by a bipolar mitotic spindle, ensuring symmetrical segregation of chromosomes. Cancer cells, however, occasionally divide into three or more directions. Such multipolar mitoses have been proposed to generate genetic diversity and thereby contribute to clonal evolution. However, this notion has been little validated experimentally. PRINCIPAL FINDINGS: Chromosome segregation and DNA content in daughter cells from multipolar mitoses were assessed by multiphoton cross sectioning and fluorescence in situ hybridization in cancer cells and non-neoplastic transformed cells. The DNA distribution resulting from multipolar cell division was found to be highly variable, with frequent nullisomies in the daughter cells. Time-lapse imaging of H2B/GFP-labelled multipolar mitoses revealed that the time from the initiation of metaphase to the beginning of anaphase was prolonged and that the metaphase plates often switched polarity several times before metaphase-anaphase transition. The multipolar metaphase-anaphase transition was accompanied by a normal reduction of cellular cyclin B levels, but typically occurred before completion of the normal separase activity cycle. Centromeric AURKB and MAD2 foci were observed frequently to remain on the centromeres of multipolar ana-telophase chromosomes, indicating that multipolar mitoses were able to circumvent the spindle assembly checkpoint with some sister chromatids remaining unseparated after anaphase. Accordingly, scoring the distribution of individual chromosomes in multipolar daughter nuclei revealed a high frequency of nondisjunction events, resulting in a near-binomial allotment of sister chromatids to the daughter cells. CONCLUSION: The capability of multipolar mitoses to circumvent the spindle assembly checkpoint system typically results in a near-random distribution of chromosomes to daughter cells. Spindle multipolarity could thus be a highly efficient

  7. Resting-state magnetoencephalography study of “small world” characteristics and cognitive dysfunction in patients with glioma

    Hu X; Lei T; Xu HZ; Zou YJ; Liu HY

    2013-01-01

    Xin-Hua Hu, Ting Lei, Hua-Zhong Xu, Yuan-Jie Zou, Hong-Yi Liu Department of Neurosurgery, Brain Hospital Affiliated to Nanjing Medical University, Nanjing, People's Republic of China Background: The purpose of this study was to analyze “small world” characteristics in glioma patients in order to understand the relationship between cognitive dysfunction and brain functional connectivity network in the resting state. Methods: Resting-state magnetoencephalography was performed in...

  8. Resting-state magnetoencephalography study of “small world” characteristics and cognitive dysfunction in patients with glioma

    Hu, Xin-Hua

    2013-01-01

    Xin-Hua Hu, Ting Lei, Hua-Zhong Xu, Yuan-Jie Zou, Hong-Yi Liu Department of Neurosurgery, Brain Hospital Affiliated to Nanjing Medical University, Nanjing, People's Republic of China Background: The purpose of this study was to analyze “small world” characteristics in glioma patients in order to understand the relationship between cognitive dysfunction and brain functional connectivity network in the resting state. Methods: Resting-state magnetoencephalography was...

  9. Does IQ affect the functional brain network involved in pseudoword reading in students with reading disability? A magnetoencephalography study

    Simos, Panagiotis G.; Fletcher, Jack M.; Andrew C. Papanicolaou

    2014-01-01

    The study examined whether individual differences in performance and verbal IQ affect the profiles of reading-related regional brain activation in 127 students experiencing reading difficulties and typical readers. Using magnetoencephalography in a pseudoword read-aloud task, we compared brain activation profiles of students experiencing word-level reading difficulties who did (n=29) or did not (n=36) meet the IQ-reading achievement discrepancy criterion. Typical readers assigned to a lower-I...

  10. Characterizing global statistical significance of spatiotemporal hot spots in magnetoencephalography/electroencephalography source space via excursion algorithms

    Xu, Yang; Sudre, Gustavo P.; Wang, Wei; Weber, Douglas J; Kass, Robert E.

    2011-01-01

    Identifying brain regions with high differential response under multiple experimental conditions is a fundamental goal of functional imaging. In many studies, regions of interest (ROIs) are not determined a priori but are instead discovered from the data, a process that requires care because of the great potential for false discovery. An additional challenge is that magnetoencephalography/electroencephalography sensor signals are very noisy, and brain source images are usually produced by ave...

  11. Neural correlation of successful cognitive behaviour therapy for spider phobia: a magnetoencephalography study.

    Wright, Barry; Alderson-Day, Ben; Prendergast, Garreth; Kennedy, Juliette; Bennett, Sophie; Docherty, Mary; Whitton, Clare; Manea, Laura; Gouws, Andre; Tomlinson, Heather; Green, Gary

    2013-12-30

    Cognitive behavioural therapy (CBT) can be an effective treatment for spider phobia, but the underlying neural correlates of therapeutic change are yet to be specified. The present study used magnetoencephalography (MEG) to study responses within the first half second, to phobogenic stimuli in a group of individuals with spider phobia prior to treatment (n=12) and then in nine of them following successful CBT (where they could touch and manage live large common house spiders) at least 9 months later. We also compared responses to a group of age-matched healthy control participants (n=11). Participants viewed static photographs of real spiders, other fear-inducing images (e.g. snakes, sharks) and neutral stimuli (e.g. kittens). Beamforming methods were used to localise sources of significant power changes in response to stimuli. Prior to treatment, participants with spider phobia showed a significant maximum response in the right frontal pole when viewing images of real spiders specifically. No significant frontal response was observed for either control participants or participants with spider phobia post-treatment. In addition, participants' subjective ratings of spider stimuli significantly predicted peak responses in right frontal regions. The implications for understanding brain-based effects of cognitive therapies are discussed. PMID:24139305

  12. Enhanced Early Neuronal Processing of Food Pictures in Anorexia Nervosa: A Magnetoencephalography Study

    Lauren R. Godier

    2016-01-01

    Full Text Available Neuroimaging studies in Anorexia Nervosa (AN have shown increased activation in reward and cognitive control regions in response to food, and a behavioral attentional bias (AB towards food stimuli is reported. This study aimed to further investigate the neural processing of food using magnetoencephalography (MEG. Participants were 13 females with restricting-type AN, 14 females recovered from restricting-type AN, and 15 female healthy controls. MEG data was acquired whilst participants viewed high- and low-calorie food pictures. Attention was assessed with a reaction time task and eye tracking. Time-series analysis suggested increased neural activity in response to both calorie conditions in the AN groups, consistent with an early AB. Increased activity was observed at 150 ms in the current AN group. Neuronal activity at this latency was at normal level in the recovered group; however, this group exhibited enhanced activity at 320 ms after stimulus. Consistent with previous studies, analysis in source space and behavioral data suggested enhanced attention and cognitive control processes in response to food stimuli in AN. This may enable avoidance of salient food stimuli and maintenance of dietary restraint in AN. A later latency of increased activity in the recovered group may reflect a reversal of this avoidance, with source space and behavioral data indicating increased visual and cognitive processing of food stimuli.

  13. Magnetoencephalography based on high-Tc superconductivity: a closer look into the brain?

    Öisjöen, F; Figueras, G A; Chukharkin, M L; Kalabukhov, A; Hedström, A; Elam, M; Winkler, D

    2011-01-01

    Magnetoencephalography (MEG) enables the study of brain activity by recording the magnetic fields generated by neural currents and has become an important technique for neuroscientists in research and clinical settings. Unlike the liquid-helium cooled low-Tc superconducting quantum interference devices (SQUIDs) that have been at the heart of modern MEG systems since their invention, high-Tc SQUIDs can operate with liquid nitrogen cooling. The relaxation of thermal insulation requirements allows for a reduction in the stand-off distance between the sensor and the room-temperature environment from a few centimeters to less than a millimeter, where MEG signal strength is significantly higher. Despite this advantage, high-Tc SQUIDs have only been used for proof-of-principle MEG recordings of well-understood evoked activity. Here we show high-Tc SQUID-based MEG may be capable of providing novel information about brain activity due to the close proximity of the sensor to the head. We have performed single- and two-...

  14. Enhanced Early Neuronal Processing of Food Pictures in Anorexia Nervosa: A Magnetoencephalography Study

    Scaife, Jessica C.; Park, Rebecca J.

    2016-01-01

    Neuroimaging studies in Anorexia Nervosa (AN) have shown increased activation in reward and cognitive control regions in response to food, and a behavioral attentional bias (AB) towards food stimuli is reported. This study aimed to further investigate the neural processing of food using magnetoencephalography (MEG). Participants were 13 females with restricting-type AN, 14 females recovered from restricting-type AN, and 15 female healthy controls. MEG data was acquired whilst participants viewed high- and low-calorie food pictures. Attention was assessed with a reaction time task and eye tracking. Time-series analysis suggested increased neural activity in response to both calorie conditions in the AN groups, consistent with an early AB. Increased activity was observed at 150 ms in the current AN group. Neuronal activity at this latency was at normal level in the recovered group; however, this group exhibited enhanced activity at 320 ms after stimulus. Consistent with previous studies, analysis in source space and behavioral data suggested enhanced attention and cognitive control processes in response to food stimuli in AN. This may enable avoidance of salient food stimuli and maintenance of dietary restraint in AN. A later latency of increased activity in the recovered group may reflect a reversal of this avoidance, with source space and behavioral data indicating increased visual and cognitive processing of food stimuli. PMID:27525258

  15. Examining Neural Synchrony in Autism During Resting State With Magnetoencephalography (MEG

    Smith Tyronda D.

    2014-09-01

    Full Text Available Autism Spectrum Disorder (ASD comprises a group of neurodevelopmental disorders associated with the functioning of the central nervous system (American Psychiatric Association, 2013. The symptoms experienced by individuals with this disorder include social impairment, communication difficulties, and repetitive and stereotyped behaviors. The etiology of ASD has yet to be determined, and it is typically diagnosed based on behavioral criteria of the Diagnostic and Statistical Manual- 5th Edition (DSM-5; APA, 2013 and confirmed with “gold standard” assessment tools such as the Autism Diagnostic Observation Schedule (ADOS and Autism Diagnostic Interview- Revised (ADI-R; Johnson Center for Child Health Development, 2014. Abnormalities in synchronous neural activity have been hypothesized to be a core pathophysiological mechanism (Cornew et al., 2012. Magnetoencephalography (MEG can measure synchronous neural activity during resting state, when the brain is not consciously engaged in cognitive processing. Coherence is a measure of the synchronicity. We examined differences in coherence during resting state in ASD, compared to neurotypical developing individuals (NT, in an attempt to identify potential biomarkers and illuminate a core etiological mechanism.

  16. Magnetoencephalography shows atypical sensitivity to linguistic sound sequences in autism spectrum disorder.

    Brennan, Jonathan R; Wagley, Neelima; Kovelman, Ioulia; Bowyer, Susan M; Richard, Annette E; Lajiness-O'Neill, Renee

    2016-09-01

    Neuroscientific evidence points toward atypical auditory processing in individuals with autism spectrum disorders (ASD), and yet, the consequences of this for receptive language remain unclear. Using magnetoencephalography and a passive listening task, we test for cascading effects on speech sound processing. Children with ASD and age-matched control participants (8-12 years old) listened to nonce linguistic stimuli that either did or did not conform to the phonological rules that govern consonant sequences in English (e.g. legal 'vimp' vs. illegal 'vimk'). Beamformer source analysis was used to isolate evoked responses (0.1-30 Hz) to these stimuli in the left and the right auditory cortex. Right auditory responses from participants with ASD, but not control participants, showed an attenuated response to illegal sequences relative to legal sequences that emerged around 330 ms after the onset of the critical phoneme. These results suggest that phonological processing is impacted in ASD, perhaps because of cascading effects from disrupted initial acoustic processing. PMID:27468112

  17. First results for a superconducting imaging-surface sensor array for magnetoencephalography

    Kraus, R.H. Jr.; Flynn, E.R.; Overton, W.; Espy, M.A.; George, J.S.; Matlachov, A.; Peters, M.V.; Ruminer, P.

    1998-12-31

    Magnetoencephalography (MEG) follows from the initial fundamental work of Cohen in 1968 and development by several groups, most notably at MIT and at NYU, based on the development of the Superconducting QUantum Interference Device (SQUID) using the Josephson effect. The SQUID`s incredible sensitivity to magnetic fields permits the measurement of the very weak magnetic fields emitted from the human brain due to intracellular neuronal currents. Current growth in MEG is dominated by multiple sensor arrays covering much of the head. These new large devices have primarily been developed and made commercially available by several companies including BTI in the US, CTF in Canada, and Neuromag in Finland. Large projects are also in place in Japan. These systems contain more than 100 sensors spaced at various intervals over the head using various configurations of magnetometers and gradiometers. The different designs available on the market are driven by factors such as detection efficiency, cost, and application. They now present a completely novel whole-head SQUID array system using a superconducting imaging-surface gradiometer concept derived at Los Alamos. Preliminary tests have demonstrated higher performance, lower noise, and additional shielding of background fields while using simpler fabrication techniques than existing whole-head MEG systems, which should reduce production costs.

  18. The neural processing of musical instrument size information in the brain investigated by magnetoencephalography

    Rupp, Andre; van Dinther, Ralph; Patterson, Roy D.

    2005-04-01

    The specific cortical representation of size was investigated by recording auditory evoked fields (AEFs) elicited by changes of instrument size and pitch. In Experiment 1, a French horn and one scaled to double the size played a three note melody around F3 or its octave, F4. Many copies of these four melodies were played in random order and the AEF was measured continuously. A similar procedure was applied to saxophone sounds in a separate run. In Experiment 2, the size and type of instrument (French horn and saxophone) were varied without changing the octave. AEFs were recorded in five subjects using magnetoencephalography and evaluated by spatio-temporal source analysis with one equivalent dipole in each hemisphere. The morphology of the source waveforms revealed that each note within the melody elicits a well-defined P1-N1-P2 AEF-complex with adaptation for the 2nd and 3rd note. At the transition of size, pitch, or both, a larger AEF-complex was evoked. However, size changes elicited a stronger N1 than pitch changes. Furthermore, this size-related N1 enhancement was larger for French horn than saxophone. The results indicate that the N1 plays an important role in the specific representation of instrument size.

  19. Enhanced Early Neuronal Processing of Food Pictures in Anorexia Nervosa: A Magnetoencephalography Study.

    Godier, Lauren R; Scaife, Jessica C; Braeutigam, Sven; Park, Rebecca J

    2016-01-01

    Neuroimaging studies in Anorexia Nervosa (AN) have shown increased activation in reward and cognitive control regions in response to food, and a behavioral attentional bias (AB) towards food stimuli is reported. This study aimed to further investigate the neural processing of food using magnetoencephalography (MEG). Participants were 13 females with restricting-type AN, 14 females recovered from restricting-type AN, and 15 female healthy controls. MEG data was acquired whilst participants viewed high- and low-calorie food pictures. Attention was assessed with a reaction time task and eye tracking. Time-series analysis suggested increased neural activity in response to both calorie conditions in the AN groups, consistent with an early AB. Increased activity was observed at 150 ms in the current AN group. Neuronal activity at this latency was at normal level in the recovered group; however, this group exhibited enhanced activity at 320 ms after stimulus. Consistent with previous studies, analysis in source space and behavioral data suggested enhanced attention and cognitive control processes in response to food stimuli in AN. This may enable avoidance of salient food stimuli and maintenance of dietary restraint in AN. A later latency of increased activity in the recovered group may reflect a reversal of this avoidance, with source space and behavioral data indicating increased visual and cognitive processing of food stimuli. PMID:27525258

  20. The fate of chrysotile-induced multipolar mitosis and aneuploid population in cultured lung cancer cells.

    Beatriz de Araujo Cortez

    Full Text Available Chrysotile is one of the six types of asbestos, and it is the only one that can still be commercialized in many countries. Exposure to other types of asbestos has been associated with serious diseases, such as lung carcinomas and pleural mesotheliomas. The association of chrysotile exposure with disease is controversial. However, in vitro studies show the mutagenic potential of chrysotile, which can induce DNA and cell damage. The present work aimed to analyze alterations in lung small cell carcinoma cultures after 48 h of chrysotile exposure, followed by 2, 4 and 8 days of recovery in fiber-free culture medium. Some alterations, such as aneuploid cell formation, increased number of cells in G2/M phase and cells in multipolar mitosis were observed even after 8 days of recovery. The presence of chrysotile fibers in the cell cultures was detected and cell morphology was observed by laser scanning confocal microscopy. After 4 and 8 days of recovery, only a few chrysotile fragments were present in some cells, and the cellular morphology was similar to that of control cells. Cells transfected with the GFP-tagged α-tubulin plasmid were treated with chrysotile for 24 or 48 h and cells in multipolar mitosis were observed by time-lapse microscopy. Fates of these cells were established: retention in metaphase, cell death, progression through M phase generating more than two daughter cells or cell fusion during telophase or cytokinesis. Some of them were related to the formation of aneuploid cells and cells with abnormal number of centrosomes.

  1. Neural effects of mental fatigue caused by continuous attention load: a magnetoencephalography study.

    Tanaka, Masaaki; Ishii, Akira; Watanabe, Yasuyoshi

    2014-05-01

    Mental fatigue can be defined as a psychobiological state caused by prolonged periods of demanding cognitive activity and manifests as a reduced efficiency in cognitive performance. Mental fatigue is one of the most significant causes of accidents in modern society. Therefore, understanding the neural mechanisms of mental fatigue is important. However, the neural mechanisms of mental fatigue are not fully understood. In this study, we investigated the neural activity that results from mental fatigue caused by a continuous attention load. We used magnetoencephalography (MEG) to evaluate the neural activities during the attention task. Ten healthy male volunteers participated in this study. They performed a continuous attention task lasting 10 min. Subjective ratings of mental fatigue, mental stress, boredom, and sleepiness were performed just after the task trial. MEG data were analyzed using narrow-band adaptive spatial filtering methods. An increase in the beta-frequency band (13-25 Hz) power in the right inferior and middle frontal gyri (Brodmann׳s areas 44 and 9 respectively) was caused by the mental fatigue. The increase in the beta-frequency band power in the right middle frontal gyrus was negatively associated with the self-reported level of mental stress and was positively associated with those of boredom and sleepiness. These results demonstrate that performing a continuous mental fatigue-inducing task causes changes in the activation of the prefrontal cortex, and manifests as an increased beta-frequency power in this brain area as well as sleepiness. Our results contribute to greater understanding of the neural mechanisms of mental fatigue. PMID:24642273

  2. Neural mechanisms of phonemic restoration for speech comprehension revealed by magnetoencephalography.

    Sunami, Kishiko; Ishii, Akira; Takano, Sakurako; Yamamoto, Hidefumi; Sakashita, Tetsushi; Tanaka, Masaaki; Watanabe, Yasuyoshi; Yamane, Hideo

    2013-11-01

    In daily communication, we can usually still hear the spoken words as if they had not been masked and can comprehend the speech when spoken words are masked by background noise. This phenomenon is known as phonemic restoration. Since little is known about the neural mechanisms underlying phonemic restoration for speech comprehension, we aimed to identify the neural mechanisms using magnetoencephalography (MEG). Twelve healthy male volunteers with normal hearing participated in the study. Participants were requested to carefully listen to and understand recorded spoken Japanese stories, which were either played forward (forward condition) or in reverse (reverse condition), with their eyes closed. Several syllables of spoken words were replaced by 300-ms white-noise stimuli with an inter-stimulus interval of 1.6-20.3s. We compared MEG responses to white-noise stimuli during the forward condition with those during the reverse condition using time-frequency analyses. Increased 3-5 Hz band power in the forward condition compared with the reverse condition was continuously observed in the left inferior frontal gyrus [Brodmann's areas (BAs) 45, 46, and 47] and decreased 18-22 Hz band powers caused by white-noise stimuli were seen in the left transverse temporal gyrus (BA 42) and superior temporal gyrus (BA 22). These results suggest that the left inferior frontal gyrus and left transverse and superior temporal gyri are involved in phonemic restoration for speech comprehension. Our findings may help clarify the neural mechanisms of phonemic restoration as well as develop innovative treatment methods for individuals suffering from impaired speech comprehension, particularly in noisy environments. PMID:24055105

  3. The neural mechanisms of re-experiencing mental fatigue sensation: a magnetoencephalography study.

    Akira Ishii

    Full Text Available There have been several studies which have tried to clarify the neural mechanisms of fatigue sensation; however fatigue sensation has multiple aspects. We hypothesized that past experience related to fatigue sensation is an important factor which contributes to future formation of fatigue sensation through the transfer to memories that are located within specific brain structures. Therefore, we aimed to investigate the neural mechanisms of fatigue sensation related to memory. In the present study, we investigated the neural activity caused by re-experiencing the fatigue sensation that had been experienced during a fatigue-inducing session. Thirteen healthy volunteers participated in fatigue and non-fatigue experiments in a crossover fashion. In the fatigue experiment, they performed a 2-back test session for 40 min to induce fatigue sensation, a rest session for 15 min to recover from fatigue, and a magnetoencephalography (MEG session in which they were asked to re-experience the state of their body with fatigue that they had experienced in the 2-back test session. In the non-fatigue experiment, the participants performed a free session for 15 min, a rest session for 15 min, and an MEG session in which they were asked to re-experience the state of their body without fatigue that they had experienced in the free session. Spatial filtering analyses of oscillatory brain activity showed that the delta band power in the left Brodmann's area (BA 39, alpha band power in the right pulvinar nucleus and the left BA 40, and beta band power in the left BA 40 were lower when they re-experienced the fatigue sensation than when they re-experienced the fatigue-free sensation, indicating that these brain regions are related to re-experiencing the fatigue sensation. Our findings may help clarify the neural mechanisms underlying fatigue sensation.

  4. Binary black hole coalescence in the extreme-mass-ratio limit: testing and improving the effective-one-body multipolar waveform

    Bernuzzi, Sebastiano; Zenginoglu, Anil

    2010-01-01

    We discuss the properties of the effective-one-body (EOB) multipolar gravitational waveform emitted by nonspinning black-hole binaries of masses $\\mu$ and $M$ in the extreme-mass-ratio limit, $\\mu/M=\

  5. Auditory cortical responses evoked by pure tones in healthy and sensorineural hearing loss subjects: functional MRI and magnetoencephalography

    ZHANG Yun-ting; GENG Zuo-jun; ZHANG Quan; LI Wei; ZHANG Jing

    2006-01-01

    Background Blood oxygen level dependent functional magnetic resonance imaging (fMRI) and magnetoencephalography are new techniques of brain functional imaging which can provide the information of excitation of neurons by measure the changes of hemodynamics and electrophysiological data of local brain tissue. The purpose of this study was to study functional brain areas evoked by pure tones in healthy and sensorineural hearing loss subjects with these techniques and to compare the differences between the two groups.Methods Thirty healthy and 30 sensorineural hearing loss subjects were included in this study. In fMRI,block-design paradigm was used. During the active epoch the participants listened to 1000 Hz, sound pressure level 140 dB pure tones at duration 500 ms, interstimulus interval 1000 ms, which presented continuously via a magnetic resonance-compatible audio system. None stimulus was executed in control epoch. In magnetoencephalography study, every subject received stimuli of 1000 Hz tone bursts delivered to the bilateral ear at duration 8 ms, interstimulus intervals 1000 ms. Sound pressure level in healthy subjects was 30 dB; in sensorineural hearing loss subjects was 20 dB above everyone' s hearing threshold respectively. All subjects were examined with 306-channel whole-scalp neuromagnetometer.Results In fMRI, all subjects showed significant activations in bilateral Heschl's gyri, anterior pole of planum temporale, planum temporale, precentral gyri, postcentral gyri, supramarginal gyri, superior temporal gyri,inferior frontal gyri, occipital lobes and cerebellums. The healthy subjects had more intensive activation in bilateral Heschl's gyri, anterior pole of planum temporale, inferior frontal gyri, left superior temporal gyri and fight planum temporale than the hearing loss subjects. But in precentral gyri, postcentral gyri and occipital lobes,the activation is more intensive in the hearing loss subjects. In magnetoencephalography study, both in the

  6. Self-assembly characteristics of a multipolar donor-acceptor-based bis-pyrene integrated molecular tweezer

    Deepak Asthana; Geeta Hundal; Pritam Mukhopadhyay

    2014-09-01

    A modular design of a molecular tweezer is presented that integrates a multipolar D--A [D: Donor, A: Acceptor] scaffold, 1-aminopyrene-based fluorophore units and L-alanine-based linkers. The synthesis of the molecule is based on two-fold aromatic nucleophilic reactions (ArSN) and coupling reactions of the acid and amino functionalities. This molecule crystallizes in a non-centrosymmteric (P21) space group.We present its rich self-assembly characteristics that involves an array of -stacking interactions. In addition, the molecular tweezer within its cleft forms H-bonding with two dimethylformamide molecules. Such multipolar D--A systems containing chiral and fluorophore units are potential candidatesfor a number of electronic and photonic applications.

  7. ADAM17 is critical for multipolar exit and radial migration of neuronal intermediate progenitor cells in mice cerebral cortex.

    Qingyu Li

    Full Text Available The radial migration of neuronal progenitor cells is critical for the development of cerebral cortex layers. They go through a critical step transforming from multipolar to bipolar before outward migration. A Disintegrin and Metalloprotease 17 (ADAM17 is a transmembrane protease which can process many substrates involved in cell-cell interaction, including Notch, ligands of EGFR, and some cell adhesion molecules. In this study, we used in utero electroporation to knock down or overexpress ADAM17 at embryonic day 14.5 (E14.5 in neuronal progenitor cells to examine the role of ADAM17 in cortical embryonic neurogenesis. Our results showed that the radial migration of ADAM17-knocked down cells were normal till E16.5 and reached the intermediate zone (IZ. Then most transfected cells stopped migration and stayed at the IZ to inner cortical plate (CP layer at E18.5, and there was higher percentage of multipolar cells at IZ layer in the ADAM17-knocked down group compared to the cells in control group. Marker staining revealed that those ADAM17-knocked down cells differentiated normally from neural stem cells (NSCs to neuronal intermediate progenitor cells (nIPCs but did not differentiate into mature neurons. The migration and multipolar exit defects caused by ADAM17 knockdown could be partially rescued by over-expressing an shRNA resistant ADAM17, while overexpressing ADAM17 alone did not affect the radial migration. Taken together, our results showed for the first time that, ADAM17 is critical in regulating the multipolar-stage exit and radial migration of the nIPCs during telencephalon cortex development in mice.

  8. ADAM17 is critical for multipolar exit and radial migration of neuronal intermediate progenitor cells in mice cerebral cortex.

    Li, Qingyu; Zhang, Zhengyu; Li, Zengmin; Zhou, Mei; Liu, Bin; Pan, Le; Ma, Zhixing; Zheng, Yufang

    2013-01-01

    The radial migration of neuronal progenitor cells is critical for the development of cerebral cortex layers. They go through a critical step transforming from multipolar to bipolar before outward migration. A Disintegrin and Metalloprotease 17 (ADAM17) is a transmembrane protease which can process many substrates involved in cell-cell interaction, including Notch, ligands of EGFR, and some cell adhesion molecules. In this study, we used in utero electroporation to knock down or overexpress ADAM17 at embryonic day 14.5 (E14.5) in neuronal progenitor cells to examine the role of ADAM17 in cortical embryonic neurogenesis. Our results showed that the radial migration of ADAM17-knocked down cells were normal till E16.5 and reached the intermediate zone (IZ). Then most transfected cells stopped migration and stayed at the IZ to inner cortical plate (CP) layer at E18.5, and there was higher percentage of multipolar cells at IZ layer in the ADAM17-knocked down group compared to the cells in control group. Marker staining revealed that those ADAM17-knocked down cells differentiated normally from neural stem cells (NSCs) to neuronal intermediate progenitor cells (nIPCs) but did not differentiate into mature neurons. The migration and multipolar exit defects caused by ADAM17 knockdown could be partially rescued by over-expressing an shRNA resistant ADAM17, while overexpressing ADAM17 alone did not affect the radial migration. Taken together, our results showed for the first time that, ADAM17 is critical in regulating the multipolar-stage exit and radial migration of the nIPCs during telencephalon cortex development in mice. PMID:23755270

  9. Multipolarity analysis for 14C high-energy resonance populated by (18O,16O) two-neutron transfer reaction

    The 12C(18O,16O)14C reaction at 84 MeV incident energy has been explored up to high excitation energy of the residual nucleus thanks to the use of the MAGNEX spectrometer to detect the ejectiles. In the region above the two-neutron separation energy, a resonance has been observed at 16.9 MeV. A multipolarity analysis of the cross section angular distribution indicates an L = 0 character for such a transition

  10. BabySQUID: A mobile, high-resolution multichannel magnetoencephalography system for neonatal brain assessment

    Okada, Yoshio; Pratt, Kevin; Atwood, Christopher; Mascarenas, Anthony; Reineman, Richard; Nurminen, Jussi; Paulson, Douglas

    2006-02-01

    We developed a prototype of a mobile, high-resolution, multichannel magnetoencephalography (MEG) system, called babySQUID, for assessing brain functions in newborns and infants. Unlike electroencephalography, MEG signals are not distorted by the scalp or the fontanels and sutures in the skull. Thus, brain activity can be measured and localized with MEG as if the sensors were above an exposed brain. The babySQUID is housed in a moveable cart small enough to be transported from one room to another. To assess brain functions, one places the baby on the bed of the cart and the head on its headrest with MEG sensors just below. The sensor array consists of 76 first-order axial gradiometers, each with a pickup coil diameter of 6mm and a baseline of 30mm, in a high-density array with a spacing of 12-14mm center-to-center. The pickup coils are 6±1mm below the outer surface of the headrest. The short gap provides unprecedented sensitivity since the scalp and skull are thin (as little as 3-4mm altogether) in babies. In an electromagnetically unshielded room in a hospital, the field sensitivity at 1kHz was ˜17fT/√Hz. The noise was reduced from ˜400to200fT/√Hz at 1Hz using a reference cancellation technique and further to ˜40fT/√Hz using a gradient common mode rejection technique. Although the residual environmental magnetic noise interfered with the operation of the babySQUID, the instrument functioned sufficiently well to detect spontaneous brain signals from babies with a signal to noise ratio (SNR) of as much as 7.6:1. In a magnetically shielded room, the field sensitivity was 17fT/√Hz at 20Hz and 30fT/√Hz at 1Hz without implementation of reference or gradient cancellation. The sensitivity was sufficiently high to detect spontaneous brain activity from a 7month old baby with a SNR as much as 40:1 and evoked somatosensory responses with a 50Hz bandwidth after as little as four averages. We expect that both the noise and the sensor gap can be reduced further by

  11. Strong orbital fluctuations in multipolar ordered states of PrV2Al20

    Matsumoto, Yosuke; Tsujimoto, Masaki; Tomita, Takahiro; Sakai, Akito; Nakatsuji, Satoru

    2016-02-01

    PrT2Al20 (T=Ti, V) are ideal systems to study the quadrupole Kondo effect and quantum criticality arising from orbital degrees of freedom. The both systems have the nonmagnetic cubic Γ3 crystal electric field ground doublet with the well separated excited state. In particular, PrV2Al20 exhibits anomalous metallic behavior above and below the multipolar ordering temperatures, reflecting the even stronger hybridization between f and conduction electrons possibly due to a proximity to an orbital quantum critical point. Here we report the anomalous metallic behaviors found in a pure single crystal of PrV2Al20. Our detailed analyses revealed that the resistivity indicates power law temperature dependence proportional to T3. Furthermore, we pointed out that the 4f electron contribution to the specific heat also exhibits power law behavior proportional to T4. Both observations are in a sharp contrast to the gapped behavior found in PrTi2Al20 and indicate the strong c-f hybridization and strong orbital fluctuations in PrV2Al20. In addition, the 4f electron contribution to the entropy in PrV2Al20 reaches only 50% of R ln 2 at an orbital ordering at T=0.75 K, suggesting another 50% of R ln 2 expected for Γ3 doublet is already released at higher temperature possibly due to quadrupole Kondo effect.

  12. Neutron star deformation due to arbitrary-order multipolar magnetic fields

    Mastrano, Alpha; Melatos, Andrew

    2013-01-01

    Certain multi-wavelength observations of neutron stars, such as intermittent radio emissions from rotation-powered pulsars beyond the pair-cascade death line, the pulse profile of the magnetar SGR 1900+14 after its 1998 August 27 giant flare, and X-ray spectral features of PSR J0821-4300 and SGR 0418+5729, suggest that the magnetic fields of non-accreting neutron stars are not purely dipolar and may contain higher-order multipoles. Here, we calculate the ellipticity of a non-barotropic neutron star with (i) a quadrupole poloidal-toroidal field, and (ii) a purely poloidal field containing arbitrary multipoles, deriving the relation between the ellipticity and the multipole amplitudes. We present, as a worked example, a purely poloidal field comprising dipole, quadrupole, and octupole components. We show the correlation between field energy and ellipticity for each multipole, that the l=4 multipole has the lowest energy, and that l=5 has the lowest ellipticity. We show how a mixed multipolar field creates an ob...

  13. Low threshold tunable spaser based on multipolar Fano resonances in disk-ring plasmonic nanostructures

    Zheng, Chunjie; Jia, Tianqing; Zhao, Hua; Zhang, Shian; Feng, Donghai; Sun, Zhenrong

    2016-01-01

    In this paper, we study theoretically spasers based on multipolar Fano resonances in disk-ring nanostructures covered with a silica layer doped with Yb3+:Er3+ used as the gain material. The electric field amplitudes at the quadrupolar mode (lasing wavelength) and the octupolar mode (pumping wavelength) are simultaneously enhanced by tens of times. Moreover, the spaser operates in a dark mode, which can reduce the radiation loss and enhance the confinement effectively. These factors work together to decrease greatly the critical gain coefficient and threshold. By adjusting the elliptic partial degrees of the nano-ring, the spasers can be tuned in the range of 1550 to 1650 nm, while the pumping light remains at the 980 nm absorption band of Yb3+ ions. Moreover, the spasers at three Fano resonance wavelengths of the disk-ring nanostructures appear in sequence with increasing the gain coefficient. The effects of the extinction coefficient on the electric field amplitudes of the pump light are also studied.

  14. Resting-state magnetoencephalography study of “small world” characteristics and cognitive dysfunction in patients with glioma

    Hu X

    2013-04-01

    Full Text Available Xin-Hua Hu, Ting Lei, Hua-Zhong Xu, Yuan-Jie Zou, Hong-Yi Liu Department of Neurosurgery, Brain Hospital Affiliated to Nanjing Medical University, Nanjing, People's Republic of China Background: The purpose of this study was to analyze “small world” characteristics in glioma patients in order to understand the relationship between cognitive dysfunction and brain functional connectivity network in the resting state. Methods: Resting-state magnetoencephalography was performed in 20 patients with glioma and 20 healthy subjects. The clustering coefficient of the resting functional connectivity network in the brain, average path length, and “small world” index (SWI were calculated. Cognitive function was estimated by testing of attention, verbal fluency, memory, athletic ability, visual-spatial ability, and intelligence. Results: Compared with healthy controls, patients with glioma showed decreased cognitive function, and diminished low and high gamma band “small world” characteristics in the resting functional connectivity network. Conclusion: The SWI is associated with cognitive function and is diminished in patients with glioma, and is therefore correlated with cognition dysfunction. Keywords: glioma, cognitive dysfunction, “small world”, functional connectivity network, magnetoencephalography

  15. CT-guided Bipolar and Multipolar Radiofrequency Ablation (RF Ablation) of Renal Cell Carcinoma: Specific Technical Aspects and Clinical Results

    Purpose. This study was designed to evaluate the clinical efficacy of CT-guided bipolar and multipolar radiofrequency ablation (RF ablation) of renal cell carcinoma (RCC) and to analyze specific technical aspects between both technologies. Methods. We included 22 consecutive patients (3 women; age 74.2 ± 8.6 years) after 28 CT-guided bipolar or multipolar RF ablations of 28 RCCs (diameter 2.5 ± 0.8 cm). Procedures were performed with a commercially available RF system (Celon AG Olympus, Berlin, Germany). Technical aspects of RF ablation procedures (ablation mode [bipolar or multipolar], number of applicators and ablation cycles, overall ablation time and deployed energy, and technical success rate) were analyzed. Clinical results (local recurrence-free survival and local tumor control rate, renal function [glomerular filtration rate (GFR)]) and complication rates were evaluated. Results. Bipolar RF ablation was performed in 12 procedures and multipolar RF ablation in 16 procedures (2 applicators in 14 procedures and 3 applicators in 2 procedures). One ablation cycle was performed in 15 procedures and two ablation cycles in 13 procedures. Overall ablation time and deployed energy were 35.0 ± 13.6 min and 43.7 ± 17.9 kJ. Technical success rate was 100 %. Major and minor complication rates were 4 and 14 %. At an imaging follow-up of 15.2 ± 8.8 months, local recurrence-free survival was 14.4 ± 8.8 months and local tumor control rate was 93 %. GFR did not deteriorate after RF ablation (50.8 ± 16.6 ml/min/1.73 m2 before RF ablation vs. 47.2 ± 11.9 ml/min/1.73 m2 after RF ablation; not significant). Conclusions. CT-guided bipolar and multipolar RF ablation of RCC has a high rate of clinical success and low complication rates. At short-term follow-up, clinical efficacy is high without deterioration of the renal function.

  16. Selective control of muscle activation with a multipolar nerve cuff electrode.

    Veraart, C; Grill, W M; Mortimer, J T

    1993-07-01

    Acute experiments were performed on adult cats to study selective activation of medial gastrocnemius, soleus, tibialis anterior, and extensor digitorum longus with a cuff electrode. A spiral nerve cuff containing twelve "dot" electrodes was implanted around the sciatic nerve and evoked muscle twitch forces were recorded in six experiments. Spatially isolated "dot" electrodes in four geometries: monopolar, longitudinal tripolar, tripolar with four common anodes, and two parallel tripoles, were combined with transverse field steering current(s) from an anode(s) located 180 degrees around from the cathode(s) to activate different regions of the nerve trunk. To quantify the degree of selectivity, a selectivity index was defined as the ratio of the force in one muscle to the force in all four muscles in response to a particular stimulus. The selectivity index was used to construct recruitment curves for a muscle with the optimal degree of selectivity. Physiological responses were correlated with the anatomical structure of the sciatic nerve by identifying the nerve fascicles innervating the four muscles, and by determining the relative positions of the electrodes and the nerve fascicles. The results indicated that the use of transverse field steering current improved selectivity. We also found that tripoles with individual dot anodes were more selective than tripoles with four common dot anodes. Stimulation with two parallel tripoles was effective in activating selectively fascicles that could not be activated selectively with only a single tripole. The multipolar cuff proved an effective method to control selectively and progressively the force in muscles innervated by fascicles that were well defined at the level of the cuff. PMID:8244425

  17. Two-Step Coronal Transport of Solar Flare Particles from Magnetic Multipolarity Sources in a Flare Region

    HUANG Yong-Nian; WANG Shi-Jin

    2001-01-01

    The transport of solar flare particles in the corona is studied. Considering the problems in terms of the character istics of a sunspot group producing solar cosmic rays and solar flare processes, we find that formation of the fast propagation process is associated with annihilation of sunspots in the group with magnetic multipolarity. The slower propagation process depends on magnetic irregularities in the corona, and the evolution of the transport is related to the flare processes. Equations for the coronal transport are proposed and their initial and boundary conditions are given. The predicted results agree with the main observational features.

  18. [Morphometry of giant multipolar neurons of the brain stem reticular formation in rats on board the Kosmos-1667 biosatellite].

    Belichenko, P V; Leontovich, T A

    1989-05-01

    Giant multipolar neurons of nucleus reticularis gigantocellularis of rats which had been kept on board the biosatellite "Kosmos-1667" were morphometrically studied. There was a trend towards the increase in the cellular surface, the maximum diameter of dendritic field, the volume of the whole dendritic territory in the test group ad in the control experimental group kept on the earth. A reliable decrease in dendritic mass oriented to nucleus vestibularis and an increase in dendritic mass oriented to the midline were also found in test group, as compared to 3 control groups. Our data were discussed in the light of nervous tissue plasticity in adult mammals. PMID:2736303

  19. The Slope Imaging Multi-polarization Photon-counting Lidar: an Advanced Technology Airborne Laser Altimeter

    Dabney, P.; Harding, D. J.; Huss, T.; Valett, S.; Yu, A. W.; Zheng, Y.

    2009-12-01

    The Slope Imaging Multi-polarization Photon-counting Lidar (SIMPL) is an airborne laser altimeter developed through the NASA Earth Science Technology Office Instrument Incubator Program with a focus on cryopshere remote sensing. The SIMPL instrument incorporates a variety of advanced technologies in order to demonstrate measurement approaches of potential benefit for improved airborne laser swath mapping and spaceflight laser altimeter missions. SIMPL incorporates beam splitting, single-photon ranging and polarimetry technologies at green and near-infrared wavelengths in order to achieve simultaneous sampling of surface elevation, slope, roughness and scattering properties, the latter used to differentiate surface types. The transmitter is a 1 nsec pulse width, 11 kHz, 1064 nm microchip laser, frequency doubled to 532 nm and split into four plane-polarized beams using birefringent calcite crystal in order to maintain co-alignment of the two colors. The 16 channel receiver splits the received energy for each beam into the two colors and each color is split into energy parallel and perpendicular to the transmit polarization plane thereby proving a measure of backscatter depolarization. The depolarization ratio is sensitive to the proportions of specular reflection and surface and volume scattering, and is a function of wavelength. The ratio can differentiate, for example, water, young translucent ice, older granular ice and snow. The solar background count rate is controlled by spatial filtering using a pinhole array and by spectral filtering using temperature-controlled narrow bandwidth filters. The receiver is fiber coupled to 16 Single Photon Counting Modules (SPCMs). To avoid range biases due to the long dead time of these detectors the probability of detection per laser fire on each channel is controlled to be below 30%, using mechanical irises and flight altitude. Event timers with 0.1 nsec resolution in combination the narrow transmit pulse yields single

  20. Excitatory cortical neurons with multipolar shape establish neuronal polarity by forming a tangentially oriented axon in the intermediate zone.

    Hatanaka, Yumiko; Yamauchi, Kenta

    2013-01-01

    The formation of axon-dendrite polarity is crucial for neuron to make the proper information flow within the brain. Although the processes of neuronal polarity formation have been extensively studied using neurons in dissociated culture, the corresponding developmental processes in vivo are still unclear. Here, we illuminate the initial steps of morphological polarization of excitatory cortical neurons in situ, by sparsely labeling their neuroepithelial progenitors using in utero electroporation and then examining their neuronal progeny in brain sections and in slice cultures. Morphological analysis showed that an axon-like long tangential process formed in progeny cells in the intermediate zone (IZ). Time-lapse imaging analysis using slice culture revealed that progeny cells with multipolar shape, after alternately extending and retracting their short processes for several hours, suddenly elongated a long process tangentially. These cells then transformed into a bipolar shape, extending a pia-directed leading process, and migrated radially leaving the tangential process behind, which gave rise to an "L-shaped" axon. Our findings suggest that neuronal polarity in these cells is established de novo from a nonpolarized stage in vivo and indicate that excitatory cortical neurons with multipolar shape in the IZ initiate axon outgrowth before radial migration into the cortical plate. PMID:22267309

  1. Comparative analysis of transverse intrafascicular multichannel, longitudinal intrafascicular and multipolar cuff electrodes for the selective stimulation of nerve fascicles

    Badia, Jordi; Boretius, Tim; Andreu, David; Azevedo-Coste, Christine; Stieglitz, Thomas; Navarro, Xavier

    2011-06-01

    The selection of a suitable nerve electrode for neuroprosthetic applications implies a trade-off between invasiveness and selectivity, wherein the ultimate goal is achieving the highest selectivity for a high number of nerve fascicles by the least invasiveness and potential damage to the nerve. The transverse intrafascicular multichannel electrode (TIME) is intended to be transversally inserted into the peripheral nerve and to be useful to selectively activate subsets of axons in different fascicles within the same nerve. We present a comparative study of TIME, LIFE and multipolar cuff electrodes for the selective stimulation of small nerves. The electrodes were implanted on the rat sciatic nerve, and the activation of gastrocnemius, plantar and tibialis anterior muscles was recorded by EMG signals. Thus, the study allowed us to ascertain the selectivity of stimulation at the interfascicular and also at the intrafascicular level. The results of this study indicate that (1) intrafascicular electrodes (LIFE and TIME) provide excitation circumscribed to the implanted fascicle, whereas extraneural electrodes (cuffs) predominantly excite nerve fascicles located superficially; (2) the minimum threshold for muscle activation with TIME and LIFE was significantly lower than with cuff electrodes; (3) TIME allowed us to selectively activate the three tested muscles when stimulating through different active sites of one device, both at inter- and intrafascicular levels, whereas selective activation using multipolar cuff (with a longitudinal tripolar stimulation configuration) was only possible for two muscles, at the interfascicular level, and LIFE did not activate selectively more than one muscle in the implanted nerve fascicle.

  2. Evidence for an All-Or-None Perceptual Response: Single-Trial Analyses of Magnetoencephalography Signals Indicate an Abrupt Transition Between Visual Perception and Its Absence

    Sekar, Krithiga; Findley, William M.; Llinás, Rodolfo R.

    2011-01-01

    Whether consciousness is an all-or-none or graded phenomenon is an area of inquiry that has received considerable interest in neuroscience and is as of yet, still debated. In this magnetoencephalography (MEG) study we used a single stimulus paradigm with sub-threshold, threshold and supra-threshold duration inputs to assess whether stimulus perception is continuous with or abruptly differentiated from unconscious stimulus processing in the brain. By grouping epochs according to stimulus ident...

  3. Atomic Forces for Geometry-Dependent Point Multipole and Gaussian Multipole Models

    Elking, Dennis M.; Perera, Lalith; Duke, Robert; Darden, Thomas; Pedersen, Lee G.

    2010-01-01

    In standard treatments of atomic multipole models, interaction energies, total molecular forces, and total molecular torques are given for multipolar interactions between rigid molecules. However, if the molecules are assumed to be flexible, two additional multipolar atomic forces arise due to 1) the transfer of torque between neighboring atoms, and 2) the dependence of multipole moment on internal geometry (bond lengths, bond angles, etc.) for geometry-dependent multipole models. In the curr...

  4. Properties of highly electronegative plasmas produced in a multipolar magnetic-confined device with a transversal magnetic filter

    Draghici, Mihai; Stamate, Eugen

    2010-01-01

    Highly electronegative plasmas were produced in Ar/SF6 gas mixtures in a dc discharge with multipolar magnetic confinement and transversal magnetic filter. Langmuir probe and mass spectrometry were used for plasma diagnostics. Plasma potential drift, the influence of small or large area biased...... electrodes on plasma parameters, the formation of the negative ion sheath and etching rates by positive and negative ions have been investigated for different experimental conditions. When the electron temperature was reduced below 1 eV the density ratio of negative ion to electron exceeded 100 even for very...... low amounts of SF6 gas. The plasma potential drift could be controlled by proper wall conditioning. A large electrode biased positively had no effect on plasma potential for density ratios of negative ions to electrons larger than 50. For similar electronegativities or higher a negative ion sheath...

  5. A multicenter study of the early detection of synaptic dysfunction in Mild Cognitive Impairment using Magnetoencephalography-derived functional connectivity

    Fernando Maestú, PhD

    2015-01-01

    Full Text Available Synaptic disruption is an early pathological sign of the neurodegeneration of Dementia of the Alzheimer's type (DAT. The changes in network synchronization are evident in patients with Mild Cognitive Impairment (MCI at the group level, but there are very few Magnetoencephalography (MEG studies regarding discrimination at the individual level. In an international multicenter study, we used MEG and functional connectivity metrics to discriminate MCI from normal aging at the individual person level. A labeled sample of features (links that distinguished MCI patients from controls in a training dataset was used to classify MCI subjects in two testing datasets from four other MEG centers. We identified a pattern of neuronal hypersynchronization in MCI, in which the features that best discriminated MCI were fronto-parietal and interhemispheric links. The hypersynchronization pattern found in the MCI patients was stable across the five different centers, and may be considered an early sign of synaptic disruption and a possible preclinical biomarker for MCI/DAT.

  6. Cross-correlation of motor activity signals from dc-magnetoencephalography, near-infrared spectroscopy, and electromyography.

    Sander, Tilmann H; Leistner, Stefanie; Wabnitz, Heidrun; Mackert, Bruno-Marcel; Macdonald, Rainer; Trahms, Lutz

    2010-01-01

    Neuronal and vascular responses due to finger movements were synchronously measured using dc-magnetoencephalography (dcMEG) and time-resolved near-infrared spectroscopy (trNIRS). The finger movements were monitored with electromyography (EMG). Cortical responses related to the finger movement sequence were extracted by independent component analysis from both the dcMEG and the trNIRS data. The temporal relations between EMG rate, dcMEG, and trNIRS responses were assessed pairwise using the cross-correlation function (CCF), which does not require epoch averaging. A positive lag on a scale of seconds was found for the maximum of the CCF between dcMEG and trNIRS. A zero lag is observed for the CCF between dcMEG and EMG. Additionally this CCF exhibits oscillations at the frequency of individual finger movements. These findings show that the dcMEG with a bandwidth up to 8 Hz records both slow and faster neuronal responses, whereas the vascular response is confirmed to change on a scale of seconds. PMID:20145717

  7. Cross-Correlation of Motor Activity Signals from dc-Magnetoencephalography, Near-Infrared Spectroscopy, and Electromyography

    Tilmann H. Sander

    2010-01-01

    Full Text Available Neuronal and vascular responses due to finger movements were synchronously measured using dc-magnetoencephalography (dcMEG and time-resolved near-infrared spectroscopy (trNIRS. The finger movements were monitored with electromyography (EMG. Cortical responses related to the finger movement sequence were extracted by independent component analysis from both the dcMEG and the trNIRS data. The temporal relations between EMG rate, dcMEG, and trNIRS responses were assessed pairwise using the cross-correlation function (CCF, which does not require epoch averaging. A positive lag on a scale of seconds was found for the maximum of the CCF between dcMEG and trNIRS. A zero lag is observed for the CCF between dcMEG and EMG. Additionally this CCF exhibits oscillations at the frequency of individual finger movements. These findings show that the dcMEG with a bandwidth up to 8 Hz records both slow and faster neuronal responses, whereas the vascular response is confirmed to change on a scale of seconds.

  8. Does IQ affect the functional brain network involved in pseudoword reading in students with reading disability? A magnetoencephalography study.

    Simos, Panagiotis G; Rezaie, Roozbeh; Papanicolaou, Andrew C; Fletcher, Jack M

    2014-01-01

    The study examined whether individual differences in performance and verbal IQ affect the profiles of reading-related regional brain activation in 127 students experiencing reading difficulties and typical readers. Using magnetoencephalography in a pseudoword read-aloud task, we compared brain activation profiles of students experiencing word-level reading difficulties who did (n = 29) or did not (n = 36) meet the IQ-reading achievement discrepancy criterion. Typical readers assigned to a lower-IQ (n = 18) or a higher IQ (n = 44) subgroup served as controls. Minimum norm estimates of regional cortical activity revealed that the degree of hypoactivation in the left superior temporal and supramarginal gyri in both RD subgroups was not affected by IQ. Moreover, IQ did not moderate the positive association between degree of activation in the left fusiform gyrus and phonological decoding ability. We did find, however, that the hypoactivation of the left pars opercularis in RD was restricted to lower-IQ participants. In accordance with previous morphometric and fMRI studies, degree of activity in inferior frontal, and inferior parietal regions correlated with IQ across reading ability subgroups. Results are consistent with current views questioning the relevance of IQ-discrepancy criteria in the diagnosis of dyslexia. PMID:24409136

  9. Does IQ affect the functional brain network involved in pseudoword reading in students with reading disability? A magnetoencephalography study

    Panagiotis G Simos

    2014-01-01

    Full Text Available The study examined whether individual differences in performance and verbal IQ affect the profiles of reading-related regional brain activation in 127 students experiencing reading difficulties and typical readers. Using magnetoencephalography in a pseudoword read-aloud task, we compared brain activation profiles of students experiencing word-level reading difficulties who did (n=29 or did not (n=36 meet the IQ-reading achievement discrepancy criterion. Typical readers assigned to a lower-IQ (n=18 or a higher IQ (n=44 subgroup served as controls. Minimum norm estimates of regional cortical activity revealed that the degree of hypoactivation in the left superior temporal and supramarginal gyri in both RD subgroups was not affected by IQ. Moreover, IQ did not moderate the positive association between degree of activation in the left fusiform gyrus and phonological decoding ability. We did find, however, that the hypoactivation of the left pars opercularis in RD was restricted to lower-IQ participants. In accordance with previous morphometric and fMRI studies, degree of activity in inferior frontal and inferior parietal regions correlated with IQ across reading ability subgroups. Results are consistent with current views questioning the relevance of IQ measures and IQ-discrepancy criteria in the diagnosis of dyslexia.

  10. Does IQ affect the functional brain network involved in pseudoword reading in students with reading disability? A magnetoencephalography study

    Simos, Panagiotis G.; Rezaie, Roozbeh; Papanicolaou, Andrew C.; Fletcher, Jack M.

    2014-01-01

    The study examined whether individual differences in performance and verbal IQ affect the profiles of reading-related regional brain activation in 127 students experiencing reading difficulties and typical readers. Using magnetoencephalography in a pseudoword read-aloud task, we compared brain activation profiles of students experiencing word-level reading difficulties who did (n = 29) or did not (n = 36) meet the IQ-reading achievement discrepancy criterion. Typical readers assigned to a lower-IQ (n = 18) or a higher IQ (n = 44) subgroup served as controls. Minimum norm estimates of regional cortical activity revealed that the degree of hypoactivation in the left superior temporal and supramarginal gyri in both RD subgroups was not affected by IQ. Moreover, IQ did not moderate the positive association between degree of activation in the left fusiform gyrus and phonological decoding ability. We did find, however, that the hypoactivation of the left pars opercularis in RD was restricted to lower-IQ participants. In accordance with previous morphometric and fMRI studies, degree of activity in inferior frontal, and inferior parietal regions correlated with IQ across reading ability subgroups. Results are consistent with current views questioning the relevance of IQ-discrepancy criteria in the diagnosis of dyslexia. PMID:24409136

  11. Auditory and cognitive deficits associated with acquired amusia after stroke: a magnetoencephalography and neuropsychological follow-up study.

    Särkämö, Teppo; Tervaniemi, Mari; Soinila, Seppo; Autti, Taina; Silvennoinen, Heli M; Laine, Matti; Hietanen, Marja; Pihko, Elina

    2010-01-01

    Acquired amusia is a common disorder after damage to the middle cerebral artery (MCA) territory. However, its neurocognitive mechanisms, especially the relative contribution of perceptual and cognitive factors, are still unclear. We studied cognitive and auditory processing in the amusic brain by performing neuropsychological testing as well as magnetoencephalography (MEG) measurements of frequency and duration discrimination using magnetic mismatch negativity (MMNm) recordings. Fifty-three patients with a left (n = 24) or right (n = 29) hemisphere MCA stroke (MRI verified) were investigated 1 week, 3 months, and 6 months after the stroke. Amusia was evaluated using the Montreal Battery of Evaluation of Amusia (MBEA). We found that amusia caused by right hemisphere damage (RHD), especially to temporal and frontal areas, was more severe than amusia caused by left hemisphere damage (LHD). Furthermore, the severity of amusia was found to correlate with weaker frequency MMNm responses only in amusic RHD patients. Additionally, within the RHD subgroup, the amusic patients who had damage to the auditory cortex (AC) showed worse recovery on the MBEA as well as weaker MMNm responses throughout the 6-month follow-up than the non-amusic patients or the amusic patients without AC damage. Furthermore, the amusic patients both with and without AC damage performed worse than the non-amusic patients on tests of working memory, attention, and cognitive flexibility. These findings suggest domain-general cognitive deficits to be the primary mechanism underlying amusia without AC damage whereas amusia with AC damage is associated with both auditory and cognitive deficits. PMID:21152040

  12. Auditory and cognitive deficits associated with acquired amusia after stroke: a magnetoencephalography and neuropsychological follow-up study.

    Teppo Särkämö

    Full Text Available Acquired amusia is a common disorder after damage to the middle cerebral artery (MCA territory. However, its neurocognitive mechanisms, especially the relative contribution of perceptual and cognitive factors, are still unclear. We studied cognitive and auditory processing in the amusic brain by performing neuropsychological testing as well as magnetoencephalography (MEG measurements of frequency and duration discrimination using magnetic mismatch negativity (MMNm recordings. Fifty-three patients with a left (n = 24 or right (n = 29 hemisphere MCA stroke (MRI verified were investigated 1 week, 3 months, and 6 months after the stroke. Amusia was evaluated using the Montreal Battery of Evaluation of Amusia (MBEA. We found that amusia caused by right hemisphere damage (RHD, especially to temporal and frontal areas, was more severe than amusia caused by left hemisphere damage (LHD. Furthermore, the severity of amusia was found to correlate with weaker frequency MMNm responses only in amusic RHD patients. Additionally, within the RHD subgroup, the amusic patients who had damage to the auditory cortex (AC showed worse recovery on the MBEA as well as weaker MMNm responses throughout the 6-month follow-up than the non-amusic patients or the amusic patients without AC damage. Furthermore, the amusic patients both with and without AC damage performed worse than the non-amusic patients on tests of working memory, attention, and cognitive flexibility. These findings suggest domain-general cognitive deficits to be the primary mechanism underlying amusia without AC damage whereas amusia with AC damage is associated with both auditory and cognitive deficits.

  13. 治理语境下的多元行政法%Multipolar Administrative Law Under Context of Governance

    王瑞雪

    2014-01-01

    治理理论给行政法治模式带来了深刻变革,治理机制全方位激励治理主体的普遍参与,尽可能地拓展、开放公共过程,多元行政法由此勃兴。与传统行政法关注行政主体与相对人权利义务关系的视角不同,治理语境下的多元行政法将视野扩展到了跨国治理机构、企业、社会组织等其他治理主体,关注治理网络中不同主体之间的协商与合作。行政法基本原则并未伴随着国家角色的回退而限缩,而是在拘束行政机关的行政行为之外,扩展到了更多承担公共治理任务的主体。治理工具也从过去政府“控制—命令”的传统方式,转向了软硬结合的多元化态势。%The governance theory brings profound changes to the administrative law. The governance mechanism encourages universal participation of different governance bodies in order to expand to more public procedures, leading to the lfourish of the multipolar administrative law. Compared to the perspective focusing on the right-obligation relationship between administrative bodies and the third party of the traditional administrative law, this multipolar administrative law under the governance context turns to pay attention to other governance bodies such as transnational governance organizations, enterprises and social organizations, etc., as well as the negotiation and cooperation among them in the governance network. Nevertheless, the administrative law basic principle does not retreat back with the role of state’s going back and it even acts on more publicgovernance bodies besides the administrative authorities. Moreover, governance tools also comprise the hybrid of soft and hard instruments, rather than the before way of single ‘common-and –control’.

  14. Study on the 143Nd(n, γα)140Ce reaction on resonance neutrons and multipolarity of γ-transitions between compound states

    The 143Nd(n, γa)140Ce reaction on resonance neutrons was investigated by the time-of-flight method at the IBR-30 pulse reactor. The width of the resonance with spin 4- at E0=55 eV was GITAsub(γa)=0.089+-0.017 μeV and at E0=159 eV was GITAsub(γa)=0.087+-0.024 μeV. The ratio of widths of resonances with spin 4- and 3- (on thermal neutrons) gave the radiative strength functions for the γ-transitions between compound states with multipolarity E1 and M1 to be equal to Ssub(γ)sup(cc)(E1)=(8+-3)x10sup(-9) MeV-3 and Ssub(γ)sup(cc) (M1)=(7+-3)x10sup(-9) Mev-3. This confirms the earlier extablished fact of the large contribution of M1 multipolarities into γ-transitions between the compound states. But still one cannot neglect the contribution of E1 multipolarity

  15. Automated Wetland Delineation from Multi-Frequency and Multi-Polarized SAR Images in High Temporal and Spatial Resolution

    Moser, L.; Schmitt, A.; Wendleder, A.

    2016-06-01

    Water scarcity is one of the main challenges posed by the changing climate. Especially in semi-arid regions where water reservoirs are filled during the very short rainy season, but have to store enough water for the extremely long dry season, the intelligent handling of water resources is vital. This study focusses on Lac Bam in Burkina Faso, which is the largest natural lake of the country and of high importance for the local inhabitants for irrigated farming, animal watering, and extraction of water for drinking and sanitation. With respect to the competition for water resources an independent area-wide monitoring system is essential for the acceptance of any decision maker. The following contribution introduces a weather and illumination independent monitoring system for the automated wetland delineation with a high temporal (about two weeks) and a high spatial sampling (about five meters). The similarities of the multispectral and multi-polarized SAR acquisitions by RADARSAT-2 and TerraSAR-X are studied as well as the differences. The results indicate that even basic approaches without pre-classification time series analysis or post-classification filtering are already enough to establish a monitoring system of prime importance for a whole region.

  16. Numerical simulation and performance improvement of a multi-polar concentric Halbach cylindrical magnet for magnetic refrigeration

    You, Yonghua; Guo, Yue; Xiao, Shuifang; Yu, Shen; Ji, Hu; Luo, Xiaobing

    2016-05-01

    Multi-polar concentric Halbach cylinders of magnets could generate the magnetic field varying considerably in the annular gaps, thus were applied in the rotary magnetic refrigerators. In the current investigation, a six-polar concentric Halbach cylinder is developed based on the ideal concentric one by the numerical simulation with COMSOL Multiphysics. Cylinder radii are optimized and magnet material profiles are adjusted for a better overall performance (Λcool). Moreover, the segmentation on the concentric cylinder is conducted for an easy fabrication, and the edge effect of finite-length device is studied. With the present investigation, it is found that a larger external radius of external cylinder facilitates a larger flux density in the high field region (| B | bar high), while Λcool could be worse. Meanwhile, with the removal of magnet materials enclosed by the equipotential lines of magnetic vector potential, the magnetic flux density in low field region (| B | bar low) drops from 0.271 to 0.0136 T, and Λcool rises from 1.36 to 1.85 T0.7. Moreover, a proper segmentation would not degrade the difference between | B | bar high and | B | bar low, on the contrary, Λcool rises by about 20.2% due to magnet materials lack for efficiency replaced by soft irons. Finally, current 3D simulation indicates the edge effect on Λcool could be trivial.

  17. Occurrence of multipolar mitoses and association with Aurora-A/-B kinases and p53 mutations in aneuploid esophageal carcinoma cells

    Münch Claudia

    2011-04-01

    Full Text Available Abstract Background Aurora kinases and loss of p53 function are implicated in the carcinogenesis of aneuploid esophageal cancers. Their association with occurrence of multipolar mitoses in the two main histotypes of aneuploid esophageal squamous cell carcinoma (ESCC and Barrett's adenocarcinoma (BAC remains unclear. Here, we investigated the occurrence of multipolar mitoses, Aurora-A/-B gene copy numbers and expression/activation as well as p53 alterations in aneuploid ESCC and BAC cancer cell lines. Results A control esophageal epithelial cell line (EPC-hTERT had normal Aurora-A and -B gene copy numbers and expression, was p53 wild type and displayed bipolar mitoses. In contrast, both ESCC (OE21, Kyse-410 and BAC (OE33, OE19 cell lines were aneuploid and displayed elevated gene copy numbers of Aurora-A (chromosome 20 polysomy: OE21, OE33, OE19; gene amplification: Kyse-410 and Aurora-B (chromosome 17 polysomy: OE21, Kyse-410. Aurora-B gene copy numbers were not elevated in OE19 and OE33 cells despite chromosome 17 polysomy. Aurora-A expression and activity (Aurora-A/phosphoT288 was not directly linked to gene copy numbers and was highest in Kyse-410 and OE33 cells. Aurora-B expression and activity (Aurora-B/phosphoT232 was higher in OE21 and Kyse-410 than in OE33 and OE19 cells. The mitotic index was highest in OE21, followed by OE33 > OE19 > Kyse-410 and EPC-hTERT cells. Multipolar mitoses occurred with high frequency in OE33 (13.8 ± 4.2%, followed by OE21 (7.7 ± 5.0% and Kyse-410 (6.3 ± 2.0% cells. Single multipolar mitoses occurred in OE19 (1.0 ± 1.0% cells. Distinct p53 mutations and p53 protein expression patterns were found in all esophageal cancer cell lines, but complete functional p53 inactivation occurred in OE21 and OE33 only. Conclusions High Aurora-A expression alone is not associated with overt multipolar mitoses in aneuploid ESCC and BAC cancer cells, as specifically shown here for OE21 and OE33 cells, respectively

  18. The Swath Imaging Multi-polarization Photon-counting Lidar (SIMPL): A Pathfinder for the LIDAR Surface Topography (LIST) Mission

    Dabney, P.; Harding, D.; Abshire, J.; Seas, A.; Sun, X.; Shuman, C.; Scambos, T.

    2007-12-01

    The Swath Imaging Multi-polarization Photon-counting Lidar (SIMPL) is an airborne prototype in development to demonstrate laser altimetry measurement methods and components that enable efficient, high-resolution, swath mapping of topography and surface properties from space. This demonstration is advancing technologies that are applicable to the global elevation mapping objectives (5 m spatial resolution, 10 cm vertical precision) of the LIDAR Surface Topography (LIST) mission recommended by the National Research Council in the Earth Science Decadal Survey report to NASA and NOAA. The main focus of this instrument development, sponsored by the NASA Earth Science and Technology Office Instrument Incubator Program, is to demonstrate an approach for detailed monitoring of ice sheet, sea ice and glacier change from a spacecraft in low Earth orbit. Although it currently emphasizes polar-region cryosphere objectives, the SIMPL approach is also applicable in other applications including measuring changes in land topography, forest height and structure, and inland water and snow cover height and extent. SIMPL employs a short-pulse (1 nsec) fiber laser transmitters operating at 1064 nm and 532 nm, a beam splitter to divide the energy into four parallel beams displaced cross-track, single photon counting modules (SPCM) detectors, and high precision timing electronics to achieve < 15 cm range precision per single detected photon. Measurement of the backscatter energy with polarization parallel and perpendicular to the laser transmit pulse provides the depolarization ratio of the surface returns at 532 and 1064 nm, in order to differentiate surface types based on their scattering properties. Results of laboratory testing of a single beam breadboard and the design and implementation of the four-beam flight instrument will be described.

  19. BRICS AND ITS ROLE IN THE SHAPING OF A MULTIPOLAR WORLD

    A. V. Vinogradov

    2014-01-01

    Full Text Available Unlike other dialogue format — G7 — BRICS countries represent not only different social and economic systems, but also different civilizations. Civilizations are the basic actors of history because they exist longer than other social subjects, and have a greater influence on world history than any other historical entity. Until today the basis of the international relations was formed by principles of inter-European relations. But the model of relations within one civilization inevitably has the limited value. Moreover, it is not the only model possible. Growing threat to Euro-Atlantic’s main advantage — economic superiority, has opened prospects to other trends. BRICS will inevitably develop from economic group into international political and intercivilizational consortium.

  20. BRICS AND ITS ROLE IN THE SHAPING OF A MULTIPOLAR WORLD

    Vinogradov, A. V.

    2015-01-01

    Unlike other dialogue format — G7 — BRICS countries represent not only different social and economic systems, but also different civilizations. Civilizations are the basic actors of history because they exist longer than other social subjects, and have a greater influence on world history than any other historical entity. Until today the basis of the international relations was formed by principles of inter-European relations. But the model of relations within one civilization inevitably has ...

  1. Multipolar Force Fields and Their Effects on Solvent Dynamics around Simple Solutes

    Jakobsen, Sofie; Bereau, Tristan; Meuwly, Markus

    2015-01-01

    The performance of multipole (MTP) and point charge (PC) force fields in classical molecular dynamics (MD) simulations of condensed-phase systems for both equilibrium and dynamical quantities is compared. MTP electrostatics provides an improved description of the anisotropic electrostatic potential......, quantities are affected by the quality of the electrostatic model. The alteration of the first solvation shell in MTP simulations is validated by comparing with lifetimes and correlation times of solute–solvent interactions from experiment. The improved dynamical behavior found in the MTP simulations......—observed for molecules parametrized using very different protocols—suggests that a systematic improvement of both equilibrium and dynamical quantities when using MTP electrostatics is possible....

  2. Experimental investigation of microwave interaction with magnetoplasma in miniature multipolar configuration using impedance measurements

    Dey, Indranuj, E-mail: indranuj@aees.kyushu-u.ac.jp; Toyoda, Yuji; Yamamoto, Naoji; Nakashima, Hideki [Department of Advanced Energy Engineering Science, Kyushu University, Kasuga 816-8580 (Japan)

    2014-09-15

    A miniature microwave plasma source employing both radial and axial magnetic fields for plasma confinement has been developed for micro-propulsion applications. Plasma is initiated by launching microwaves via a short monopole antenna to circumvent geometrical cutoff limitations. The amplitude and phase of the forward and reflected microwave power is measured to obtain the complex reflection coefficient from which the equivalent impedance of the plasma source is determined. Effect of critical plasma density condition is reflected in the measurements and provides insight into the working of the miniature plasma source. A basic impedance calculation model is developed to help in understanding the experimental observations. From experiment and theory, it is seen that the equivalent impedance magnitude is controlled by the coaxial discharge boundary conditions, and the phase is influenced primarily by the plasma immersed antenna impedance.

  3. Multipolarity analysis for {sup 14}C high-energy resonance populated by ({sup 18}O,{sup 16}O) two-neutron transfer reaction

    Carbone, D., E-mail: carboned@lns.infn.it; Cavallaro, M.; Bondì, M.; Agodi, C.; Cunsolo, A. [INFN-Laboratori Nazionali del Sud, Catania (Italy); Cappuzzello, F. [INFN-Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Catania (Italy); Azaiez, F.; Franchoo, S.; Khan, E. [Institut de Physique Nucleaire, Universitè Paris-Sud, Orsay (France); Bonaccorso, A. [INFN-Sezione di Pisa, Pisa (Italy); Fortunato, L. [Dipartimento di Fisica e Astronomia, Università di Padova, Padova (Italy); INFN-Sezione di Padova, Padova (Italy); Foti, A. [Dipartimento di Fisica e Astronomia, Università di Catania, Catania (Italy); INFN-Sezione di Catania, Catania (Italy); Linares, R.; Lubian, J. [Instituto de Fisica, Universidade Federal Fluminense, Niteroi (Brazil); Scarpaci, J. A. [Centre de Sciences Nucleaires et de Sciences de Matieres, Universitè Paris-Sud, Orsay (France); Vitturi, A. [INFN-Sezione di Padova, Padova (Italy); INFN-Sezione di Catania, Catania (Italy)

    2015-10-15

    The {sup 12}C({sup 18}O,{sup 16}O){sup 14}C reaction at 84 MeV incident energy has been explored up to high excitation energy of the residual nucleus thanks to the use of the MAGNEX spectrometer to detect the ejectiles. In the region above the two-neutron separation energy, a resonance has been observed at 16.9 MeV. A multipolarity analysis of the cross section angular distribution indicates an L = 0 character for such a transition.

  4. The Fate of Sub-micron Circumplanetary Dust Grains II: Multipolar Fields

    Jontof-Hutter, Daniel

    2012-01-01

    We study the radial and vertical stability of dust grains launched with all charge-to-mass ratios at arbitrary distances from rotating planets with complex magnetic fields. We show that the aligned dipole magnetic field model analyzed by Jontof-Hutter and Hamilton (2012) is an excellent approximation in most cases, but that fundamentally new physics arises with the inclusion of non-axisymmetric magnetic field terms. In particular, large numbers of distant negatively-charged dust grains, stable in a magnetic dipole, can be driven to escape by a more complex field. We trace the origin of the instability to overlapping Lorentz resonances which are extremely powerful when the gravitational and electromagnetic forces on a dust grain are comparable. These resonances enable a dust grain to tap the spin energy of the planet to power its escape. We also explore the relatively minor influence of different launch speeds and the far more important effects of variable grain charge. Only the latter are capable of significa...

  5. C3G/Rapgef1 Is Required in Multipolar Neurons for the Transition to a Bipolar Morphology during Cortical Development.

    Bhavin Shah

    Full Text Available The establishment of a polarized morphology is essential for the development and function of neurons. During the development of the mammalian neocortex, neurons arise in the ventricular zone (VZ from radial glia cells (RGCs and leave the VZ to generate the cortical plate (CP. During their migration, newborn neurons first assume a multipolar morphology in the subventricular zone (SVZ and lower intermediate zone (IZ. Subsequently, they undergo a multi-to-bipolar (MTB transition to become bipolar in the upper IZ by developing a leading process and a trailing axon. The small GTPases Rap1A and Rap1B act as master regulators of neural cell polarity in the developing mouse neocortex. They are required for maintaining the polarity of RGCs and directing the MTB transition of multipolar neurons. Here we show that the Rap1 guanine nucleotide exchange factor (GEF C3G (encoded by the Rapgef1 gene is a crucial regulator of the MTB transition in vivo by conditionally inactivating the Rapgef1 gene in the developing mouse cortex at different time points during neuronal development. Inactivation of C3G results in defects in neuronal migration, axon formation and cortical lamination. Live cell imaging shows that C3G is required in cortical neurons for both the specification of an axon and the initiation of radial migration by forming a leading process.

  6. C3G/Rapgef1 Is Required in Multipolar Neurons for the Transition to a Bipolar Morphology during Cortical Development.

    Shah, Bhavin; Lutter, Daniela; Bochenek, Magdalena L; Kato, Katsuhiro; Tsytsyura, Yaroslav; Glyvuk, Natalia; Sakakibara, Akira; Klingauf, Jürgen; Adams, Ralf H; Püschel, Andreas W

    2016-01-01

    The establishment of a polarized morphology is essential for the development and function of neurons. During the development of the mammalian neocortex, neurons arise in the ventricular zone (VZ) from radial glia cells (RGCs) and leave the VZ to generate the cortical plate (CP). During their migration, newborn neurons first assume a multipolar morphology in the subventricular zone (SVZ) and lower intermediate zone (IZ). Subsequently, they undergo a multi-to-bipolar (MTB) transition to become bipolar in the upper IZ by developing a leading process and a trailing axon. The small GTPases Rap1A and Rap1B act as master regulators of neural cell polarity in the developing mouse neocortex. They are required for maintaining the polarity of RGCs and directing the MTB transition of multipolar neurons. Here we show that the Rap1 guanine nucleotide exchange factor (GEF) C3G (encoded by the Rapgef1 gene) is a crucial regulator of the MTB transition in vivo by conditionally inactivating the Rapgef1 gene in the developing mouse cortex at different time points during neuronal development. Inactivation of C3G results in defects in neuronal migration, axon formation and cortical lamination. Live cell imaging shows that C3G is required in cortical neurons for both the specification of an axon and the initiation of radial migration by forming a leading process. PMID:27111087

  7. Multipolarity or cosmopolitanism?

    Hansen, Allan Dreyer

    of hegemony – as developed by herself and Laclau in Hegemony and Socialist Strategy, (Laclau and Mouffe,1985), precisely allows us to see the distance between universal values, such as freedom and equality for all, and their actual interpretation and use. The fact that the West are using democracy and human......In a series of publications Chantal Mouffe (2004, 2005a, 2005b, 2008, 2009, 2013) has criticized cosmopolitanism for its lack of conceptualization of power, conflict and struggle, in short of politics. Even though this critique is largely well placed, the conclusions drawn from the analysis...... by Mouffe are flawed. As she puts it, if a cosmopolitan democracy “was ever realized, it could only signify the world hegemony of a dominant power that would have been able to impose its conception of the world on the entire planet and which, identifying its interests with those of humanity, would treat any...

  8. Moving Toward Multipolarity

    KERRY; BROWN

    2009-01-01

    Prospects of an improved relationship between China and Europe are brightening but expectations may have to be reined in Since 2003, the European Union (EU) and China have described their relationship as one of "strategic partnership." But the term is one that

  9. A MULTIPOLAR COLD WAR

    GAGIK HARUTYUNYAN

    2007-01-01

    The present article draws parallels between existing political realities and the onesthat occurred during the Cold War in the second half of the 20th century. Similarto the previous one, the new Cold War is consistent with the logic of «the policy ofdeterrence» which nowadays is directed against the United States. «Cold War-1»reflected stiff competition between the two opposite ideological and geopoliticalprograms. Meanwhile, today we have several poles of power and, therefore, «ColdWar-2» is...

  10. Per-point and per-field contextual classification of multipolarization and multiple incidence angle aircraft L-band radar data

    Hoffer, Roger M.; Hussin, Yousif Ali

    1989-01-01

    Multipolarized aircraft L-band radar data are classified using two different image classification algorithms: (1) a per-point classifier, and (2) a contextual, or per-field, classifier. Due to the distinct variations in radar backscatter as a function of incidence angle, the data are stratified into three incidence-angle groupings, and training and test data are defined for each stratum. A low-pass digital mean filter with varied window size (i.e., 3x3, 5x5, and 7x7 pixels) is applied to the data prior to the classification. A predominately forested area in northern Florida was the study site. The results obtained by using these image classifiers are then presented and discussed.

  11. Reduction of Fluoroscopic Exposure Using a New Fluoroscopy Integrating Technology in a 3D-Mapping System During Pulmonary Vein Isolation With a Circular Multipolar Irrigated Catheter.

    Blockhaus, Christian; Schmidt, Jan; Kurt, Muhammed; Clasen, Lukas; Brinkmeyer, Christoph; Katsianos, Efstratios; Müller, Patrick; Gerguri, Shqipe; Kelm, Malte; Shin, Dong-In; Makimoto, Hisaki

    2016-05-25

    Pulmonary vein isolation (PVI) is a cornerstone therapy in patients with atrial fibrillation (AF). With increasing numbers of PVI procedures, demand arises to reduce the cumulative fluoroscopic radiation exposure for both the physician and the patient. New technologies are emerging to address this issue. Here, we report our first experiences with a new fluoroscopy integrating technology in addition to a current 3D-mapping system. The new fluoroscopy integrating system (FIS) with 3D-mapping was used prospectively in 15 patients with AF. Control PVI cases (n = 37) were collected retrospectively as a complete series. Total procedure time (skin to skin), fluoroscopic time, and dose-area-product (DAP) data were analyzed. All PVI procedures were performed by one experienced physician using a commercially available circular multipolar irrigated ablation catheter. All PVI procedures were successfully undertaken without major complications. Baseline characteristics of the two groups showed no significant differences. In the group using the FIS, the fluoroscopic time and DAP were significantly reduced from 571 ± 187 seconds versus 1011 ± 527 seconds (P = 0.0029) and 4342 ± 2073 cGycm(2) versus 6208 ± 3314 cGycm(2) (P = 0.049), respectively. Mean procedure time was not significantly affected and was 114 ± 31 minutes versus 104 ± 24 minutes (P = 0.23) by the FIS.The use of the new FIS with the current 3D-mapping system enables a significant reduction of the total fluoroscopy time and DAP compared to the previous combination of 3D-mapping system plus normal fluoroscopy during PVI utilizing a circular multipolar irrigated ablation catheter. However, the concomitant total procedure time is not affected. Thus, the new system reduces the radiation exposure for both the physicians and patients. PMID:27181037

  12. Anti-Stress, Behavioural and Magnetoencephalography Effects of an l-Theanine-Based Nutrient Drink: A Randomised, Double-Blind, Placebo-Controlled, Crossover Trial

    David J. White

    2016-01-01

    Full Text Available l-theanine (γ-glutamylethylamide is an amino acid found primarily in the green tea plant. This study explored the effects of an l-theanine-based nutrient drink on mood responses to a cognitive stressor. Additional measures included an assessment of cognitive performance and resting state alpha oscillatory activity using magnetoencephalography (MEG. Thirty-four healthy adults aged 18–40 participated in this double-blind, placebo-controlled, balanced crossover study. The primary outcome measure, subjective stress response to a multitasking cognitive stressor, was significantly reduced one hour after administration of the l-theanine drink when compared to placebo. The salivary cortisol response to the stressor was reduced three hours post-dose following active treatment. No treatment-related cognitive performance changes were observed. Resting state alpha oscillatory activity was significantly greater in posterior MEG sensors after active treatment compared to placebo two hours post-dose; however, this effect was only apparent for those higher in trait anxiety. This change in resting state alpha oscillatory activity was not correlated with the change in subjective stress response or the cortisol response, suggesting further research is required to assess the functional relevance of these treatment-related changes in resting alpha activity. These findings further support the anti-stress effects of l-theanine.

  13. Anti-Stress, Behavioural and Magnetoencephalography Effects of an L-Theanine-Based Nutrient Drink: A Randomised, Double-Blind, Placebo-Controlled, Crossover Trial.

    White, David J; de Klerk, Suzanne; Woods, William; Gondalia, Shakuntla; Noonan, Chris; Scholey, Andrew B

    2016-01-01

    L-theanine (γ-glutamylethylamide) is an amino acid found primarily in the green tea plant. This study explored the effects of an L-theanine-based nutrient drink on mood responses to a cognitive stressor. Additional measures included an assessment of cognitive performance and resting state alpha oscillatory activity using magnetoencephalography (MEG). Thirty-four healthy adults aged 18-40 participated in this double-blind, placebo-controlled, balanced crossover study. The primary outcome measure, subjective stress response to a multitasking cognitive stressor, was significantly reduced one hour after administration of the L-theanine drink when compared to placebo. The salivary cortisol response to the stressor was reduced three hours post-dose following active treatment. No treatment-related cognitive performance changes were observed. Resting state alpha oscillatory activity was significantly greater in posterior MEG sensors after active treatment compared to placebo two hours post-dose; however, this effect was only apparent for those higher in trait anxiety. This change in resting state alpha oscillatory activity was not correlated with the change in subjective stress response or the cortisol response, suggesting further research is required to assess the functional relevance of these treatment-related changes in resting alpha activity. These findings further support the anti-stress effects of L-theanine. PMID:26797633

  14. Parametrized post-Newtonian theory of reference frames, multipolar expansions and equations of motion in the N-body problem

    along with the law of relativistic precession of its spatial axes. These transformations depend on the PPN parameters β and γ, generalize general relativistic transformations of the IAU 2000 resolutions, and should be used in the data processing of the solar system gravitational experiments aimed to detect the presence of the scalar field. These PPN transformations are also applicable in the precise time-keeping metrology, celestial mechanics, astrometry, geodesy and navigation.We consider a multipolar post-Newtonian expansion of the gravitational and scalar fields and construct a set of internal and external gravitational multipoles depending on the parameters β and γ. These PPN multipoles generalize the Thorne-Blanchet-Damour multipoles defined in harmonic coordinates of general theory of relativity. The PPN multipoles of the scalar-tensor theory of gravity are split in three classes-active, conformal, and scalar multipoles. Only two of them are algebraically independent and we chose to work with the conformal and active multipoles. We derive the laws of conservations of the multipole moments and show that they must be formulated in terms of the conformal multipoles. We focus then on the law of conservation of body's linear momentum which is defined as a time derivative of the conformal dipole moment of the body in the local coordinates. We prove that the local force violating the law of conservation of the body's linear momentum depends exclusively on the active multipole moments of the body along with a few other terms which depend on the internal structure of the body and are responsible for the violation of the strong principle of equivalence (the Nordtvedt effect).The PPN translational equations of motion of extended bodies in the global coordinate frame and with all gravitational multipoles taken into account are derived from the law of conservation of the body's linear momentum supplemented by the law of motion of the origin of the local frame derived from

  15. Using Structural Equation Modeling to Assess Functional Connectivity in the Brain: Power and Sample Size Considerations

    Sideridis, Georgios; Simos, Panagiotis; Papanicolaou, Andrew; Fletcher, Jack

    2014-01-01

    The present study assessed the impact of sample size on the power and fit of structural equation modeling applied to functional brain connectivity hypotheses. The data consisted of time-constrained minimum norm estimates of regional brain activity during performance of a reading task obtained with magnetoencephalography. Power analysis was first…

  16. Detection and Magnetic Source Imaging of Fast Oscillations (40-160 Hz) Recorded with Magnetoencephalography in Focal Epilepsy Patients.

    von Ellenrieder, Nicolás; Pellegrino, Giovanni; Hedrich, Tanguy; Gotman, Jean; Lina, Jean-Marc; Grova, Christophe; Kobayashi, Eliane

    2016-03-01

    We present a framework to detect fast oscillations (FOs) in magnetoencephalography (MEG) and to perform magnetic source imaging (MSI) to determine the location and extent of their generators in the cortex. FOs can be of physiologic origin associated to sensory processing and memory consolidation. In epilepsy, FOs are of pathologic origin and biomarkers of the epileptogenic zone. Seventeen patients with focal epilepsy previously confirmed with identified FOs in scalp electroencephalography (EEG) were evaluated. To handle data deriving from large number of sensors (275 axial gradiometers) we used an automatic detector with high sensitivity. False positives were discarded by two human experts. MSI of the FOs was performed with the wavelet based maximum entropy on the mean method. We found FOs in 11/17 patients, in only one patient the channel with highest FO rate was not concordant with the epileptogenic region and might correspond to physiologic oscillations. MEG FOs rates were very low: 0.02-4.55 per minute. Compared to scalp EEG, detection sensitivity was lower, but the specificity higher in MEG. MSI of FOs showed concordance or partial concordance with proven generators of seizures and epileptiform activity in 10/11 patients. We have validated the proposed framework for the non-invasive study of FOs with MEG. The excellent overall concordance with other clinical gold standard evaluation tools indicates that MEG FOs can provide relevant information to guide implantation for intracranial EEG pre-surgical evaluation and for surgical treatment, and demonstrates the important added value of choosing appropriate FOs detection and source localization methods. PMID:26830767

  17. Crisis del lóbulo temporal registrada mediante magnetoencefalografía: caso clínico Temporal lobe seizure recorded by magnetoencephalography: case report

    Carlos Amo

    2004-09-01

    Full Text Available La localización del inicio de las crisis es un factor importante para la evaluación prequirúrgica de la epilepsia. En este trabajo se describe la localización del inicio de una crisis registrada mediante magnetoencefalografía (MEG en un niño de 12 años que presenta crisis parciales complejas farmacorresistentes. La RM muestra una lesión de 20mm de diámetro en el hipocampo izquierdo. EEG de superficie con ondas theta temporales izquierdas. Registro MEG interictal con punta-onda aislada posterior e inferior a la lesión de la RM. Registro MEG ictal con punta-onda (2 Hz. La localización de los dipolos indica el inicio de la crisis en la circunvolución temporal inferior en la misma localización que la actividad interictal MEG. Esta actividad ictal se propaga bilateralmente a áreas frontales. El registro corticográfico intraquirúrgico confirma los resultados de la localización interictal mediante MEG.Ictal onset localization is a important factor in presurgical evaluation of epilepsy. This paper describes the localization of a seizure onset recorded by magnetoencephalography (MEG from a 12-year-old male patient who suffered from complex partial drug-resistant seizures. MRI revealed a 20mm diameter lesion located in left hippocampus. Scalp EEG showed left temporal theta waves. Interictal MEG registrations detected isolated spike-wave activity posterior and inferior to the MRI lesion. Ictal MEG showed continuous spike-wave activity (2 Hz. Dipole localization sited seizure onset in the inferior left temporal gyrus, the same localization of the interictal MEG activity. This ictal activity spreads bilaterally to frontal areas. Intrasurgical electrocorticography recording confirmed interictal MEG results.

  18. Spectral power and functional connectivity changes during mindfulness meditation with eyes open: A magnetoencephalography (MEG) study in long-term meditators.

    Wong, W P; Camfield, D A; Woods, W; Sarris, J; Pipingas, A

    2015-10-01

    Whilst a number of previous studies have been conducted in order to investigate functional brain changes associated with eyes-closed meditation techniques, there is a relative scarcity in the literature with regards to changes occurring during eyes-open meditation. The current project used magnetoencephalography (MEG) to investigate differences in spectral power and functional connectivity between 11 long-term mindfulness meditators (LTMMs) with >5 years of experience and 12 meditation-naïve control participants both during baseline eyes-open rest and eyes-open open-monitoring (OM) mindfulness meditation. During resting with eyes-open, prior to meditating, greater mean alpha power was observed for LTMMs in comparison to controls. However, during the course of OM meditation, a significantly greater increase in theta power was observed over a broad fronto-centro-parietal region for control participants in comparison to LTMMs. In contrast, whole-head mean connectivity was found to be significantly greater for long-term meditators in comparison to controls in the theta band both during rest as well as during meditation. Additionally, mean connectivity was significantly lower for long-term meditators in the low gamma band during rest and significantly lower in both low and high gamma bands during meditation; and the variance of low-gamma connectivity scores for long-term meditators was significantly decreased compared to the control group. The current study provides important new information as to the trait functional changes in brain activity associated with long-term mindfulness meditation, as well as the state changes specifically associated with eyes-open open monitoring meditation techniques. PMID:26166440

  19. Interpreting sea surface slicks on the basis of the normalized radar cross-section model using RADARSAT-2 copolarization dual-channel SAR images

    Ivonin, D. V.; Skrunes, S.; Brekke, C.; Ivanov, A. Yu.

    2016-03-01

    A simple automatic multipolarization technique for discrimination of main types of thin oil films (of thickness less than the radio wave skin depth) from natural ones is proposed. It is based on a new multipolarization parameter related to the ratio between the damping in the slick of specially normalized resonant and nonresonant signals calculated using the normalized radar cross-section model proposed by Kudryavtsev et al. (2003a). The technique is tested on RADARSAT-2 copolarization (VV/HH) synthetic aperture radar images of slicks of a priori known provenance (mineral oils, e.g., emulsion and crude oil, and plant oil served to model a natural slick) released during annual oil-on-water exercises in the North Sea in 2011 and 2012. It has been shown that the suggested multipolarization parameter gives new capabilities in interpreting slicks visible on synthetic aperture radar images while allowing discrimination between mineral oil and plant oil slicks.

  20. Binary black hole coalescence in the extreme-mass-ratio limit: Testing and improving the effective-one-body multipolar waveform

    We discuss the properties of the effective-one-body (EOB) multipolar gravitational waveform emitted by nonspinning black-hole binaries of masses μ and M in the extreme-mass-ratio limit μ/M=ν-4 rad and maintain then a remarkably accurate phase coherence during the long inspiral (∼33 orbits), accumulating only about -2x10-3 rad until the last stable orbit, i.e. Δφ/φ∼-5.95x10-6. We obtain such accuracy without calibrating the analytically resummed EOB waveform to numerical data, which indicates the aptitude of the EOB waveform for studies concerning the Laser Interferometer Space Antenna. We then improve the behavior of the EOB waveform around merger by introducing and tuning next-to-quasicircular corrections in both the gravitational wave amplitude and phase. For each multipole we tune only four next-to-quasicircular parameters by requiring compatibility between EOB and Regge-Wheeler-Zerilli waveforms at the light ring. The resulting phase difference around the merger time is as small as ±0.015 rad, with a fractional amplitude agreement of 2.5%. This suggest that next-to-quasicircular corrections to the phase can be a useful ingredient in comparisons between EOB and numerical-relativity waveforms.

  1. Multipolar phases and magnetically hidden order: review of the heavy-fermion compound Ce1‑x La x B6

    Cameron, Alistair S.; Friemel, Gerd; Inosov, Dmytro S.

    2016-06-01

    Cerium hexaboride is a cubic f-electron heavy-fermion compound that displays a rich array of low-temperature magnetic ordering phenomena which have been the subject of investigation for more than 50 years. Its complex behaviour is the result of competing interactions, with both itinerant and local electrons playing important roles. Investigating this material has proven to be a substantial challenge, in particular because of the appearance of a ‘magnetically hidden order’ phase, which remained elusive to neutron-scattering investigations for many years. It was not until the development of modern x-ray scattering techniques that the long suspected multipolar origin of this phase was confirmed. Doping with non-magnetic lanthanum dilutes the magnetic cerium sublattice and reduces the f-electron count, bringing about substantial changes to the ground state with the emergence of new phases and quantum critical phenomena. To this day, Ce1‑x La x B6 and its related compounds remain a subject of intense interest. Despite the substantial progress in understanding their behaviour, they continue to reveal new and unexplained physical phenomena. Here we present a review of the accumulated body of knowledge on this family of materials in order to provide a firm standpoint for future investigations.

  2. The ablated volume and the thermal field distribution in swine vertebral body created by multi-polar radiofrequency ablation: an experiment in vitro

    Objective: To observe the extent of bone coagulation and the thermal field distribution created in ablating the swine vertebral bodies in vitro with multi-polar radiofrequency and to discuss the correlation between the electrode position in the vertebral body and the safety of the spinal cord as well as the soft tissue injury around the vertebral body. Methods: Thirty fresh adult porcine vertebrae were randomly and equally divided into two groups. The depth of the electrode needle was 10 mm or 20 mm.When the ablation process reached to a stable state, the temperature at the scheduled spots was estimated. Twenty minutes after ablation, the vertebral body was cut along the electrode needle plane and also along the plane perpendicular to the electrode needle to observe the extent of bone coagulation. Results: The temperature at the scheduled spots reached to a stable state in 3.5 minutes. The more close to the electrode the spot was, the more quickly the temperature rose. No soft tissue injury around the vertebral body was observed in both groups and no spinal cord injury occurred when the electrode needle was 10 mm or 20 mm deep in the vertebral body. Conclusion: In treating vertebral metastases, the radiofrequency ablation is safe and reliable if the posterior wall of the vertebral body remains intact. (authors)

  3. The multipolar magnetic fields of accreting pre-main-sequence stars: B at the inner disk, B along the accretion flow, and B at the accretion shock

    Gregory, Scott G; Hussain, Gaitee A J

    2016-01-01

    Zeeman-Doppler imaging studies have revealed the complexity of the large-scale magnetic fields of accreting pre-main-sequence stars. All have multipolar magnetic fields with the octupole component being the dominant field mode for many of the stars studied thusfar. Young accreting stars with fully convective interiors often feature simple axisymmetric magnetic fields with dipole components of order a kilo-Gauss (at least those of mass $\\gtrsim0.5\\,{\\rm M}_\\odot$), while those with substantially radiative interiors host more complex non-axisymmetric magnetic fields with dipole components of order a few 0.1 kilo-Gauss. Here, via several simple examples, we demonstrate that i). in most cases, the dipole component alone can be used to estimate the disk truncation radius (but little else); ii) due the presence of higher order magnetic field components, the field strength in the accretion spots is far in excess of that expected if a pure dipole magnetic field is assumed. (Fields of $\\sim$6$\\,{\\rm kG}$ have been mea...

  4. Spatiotemporal Accuracy of Gradient Magnetic-Field Topography (GMFT) Confirmed by Simultaneous Magnetoencephalography and Intracranial Electroencephalography Recordings in Patients with Intractable Epilepsy.

    Shirozu, Hiroshi; Hashizume, Akira; Masuda, Hiroshi; Fukuda, Masafumi; Ito, Yosuke; Nakayama, Yoko; Higashijima, Takefumi; Kameyama, Shigeki

    2016-01-01

    Gradient magnetic-field topography (GMFT) is one method for analyzing magnetoencephalography (MEG) and representing the spatiotemporal dynamics of activity on the brain surface. In contrast to spatial filters, GMFT does not include a process reconstructing sources by mixing sensor signals with adequate weighting. Consequently, noisy sensors have localized and limited effects on the results, and GMFT can handle MEG recordings with low signal-to-noise ratio. This property is derived from the principle of the planar-type gradiometer, which obtains maximum gradient magnetic-field signals just above the electrical current source. We assumed that this characteristic allows GMFT to represent even faint changes in brain activities that cannot be achieved with conventional equivalent current dipole analysis or spatial filters. GMFT is thus hypothesized to represent brain surface activities from onset to propagation of epileptic discharges. This study aimed to validate the spatiotemporal accuracy of GMFT by analyzing epileptic activities using simultaneous MEG and intracranial electroencephalography (iEEG) recordings. Participants in this study comprised 12 patients with intractable epilepsy. Epileptic spikes simultaneously detected on both MEG and iEEG were analyzed by GMFT and voltage topography (VT), respectively. Discrepancies in spatial distribution between GMFT and VT were evaluated for each epileptic spike. On the lateral cortices, areas of GMFT activity onset were almost concordant with VT activities arising at the gyral unit level (concordance rate, 66.7-100%). Median time lag between GMFT and VT at onset in each patient was 11.0-42.0 ms. On the temporal base, VT represented basal activities, whereas GMFT failed but instead represented propagated activities of the lateral temporal cortices. Activities limited to within the basal temporal or deep brain region were not reflected on GMFT. In conclusion, GMFT appears to accurately represent brain activities of the

  5. Multi-polarization Antenna for Mobile Communication%一种适用于移动通信的多极化天线

    刘宗全; 钱祖平; 韩振平; 倪为民

    2011-01-01

    为满足移动通信系统极化复用的需求,文章设计了一种新型多极化天线。该天线有两个独立端口,分别工作在圆极化和线极化,可以接收空间三个互相正交的电场分量。实测结果表明,线极化和圆极化端口回波损耗S_(11)小于-10 dB的工作频带分别为1.69 GHz~1.84 GHz和1.66 GHz~2.32GHz,圆极化轴比(AR)小于3dB的工作频带为1.77 GHz~1.97 GHz,端口间隔离度均在-15 dB以下,满足了移动通信系统天线设计小型化的要求。%To meet the polarization multiplexing demand of the mobile communication system, a new multi-polarization antenna was designed.The antenna contains two independent ports working with linear and circular polarization respectively,so that it can receive three orthogonal components of electric field in space.The measured results show that the impedance bandwidth whose S_(11) is less than -10 dB is 1.69 GHz~l.84 GHz and 1.66 GHz~2.32 GHz for linear-polarization and circular-polarization ports respectively.The bandwidth for AR3 dB is 1.77 GHz~1.97 GHz.The isolation between the two ports is below -15 dB.The antenna can meet the miniaturization demand of the mobile communication system antenna design.

  6. Increased doublecortin (DCX expression and incidence of DCX-immunoreactive multipolar cells in the subventricular zone-olfactory bulb system of suicides

    Marissa E Maheu

    2015-06-01

    Full Text Available Postmortem studies have confirmed the occurrence of adult hippocampal neurogenesis in humans and implicated this process in antidepressant response, yet neurogenesis in other regions remains to be examined in the context of depression. Here we assess the extent of subventricular zone-olfactory bulb (SVZ-OB neurogenesis in adult humans having died by suicide. Protein expression of proliferative and neurogenic markers Sox2, proliferating cell nuclear antigen, and doublecortin (DCX were examined in postmortem SVZ and OB samples from depressed suicides and matched sudden-death controls. In the SVZ, DCX-immunoreactive (IR cells displayed phenotypes typical of progenitors, whereas in the olfactory tract (OT, they were multipolar with variable size and morphologies suggestive of differentiating cells. DCX expression was significantly increased in the OB of suicides, whereas SVZ DCX expression was higher among unmedicated, but not antidepressant-treated, suicides. Although very few DCX-IR cells were present in the control OT, they were considerably more common in suicides and correlated with OB DCX levels. Suicides also displayed higher DCX-IR process volumes. These results support the notion that OB neurogenesis is minimal in adult humans. They further indicate that the differentiation and migration of SVZ-derived neuroblasts may be altered in unmedicated suicides, leading to an accumulation of ectopically-differentiating cells in the OT. Normal SVZ DCX expression among suicides receiving antidepressants suggests a potentially novel mode of action of antidepressant medication. Given the modest group sizes and rarity of DCX-IR cells assessed here, a larger-scale characterization will be required before firm conclusions can be made regarding the identity of these cells.

  7. A Rússia na ordem mundial: com o Ocidente, com o Oriente ou um pólo autônomo em um mundo multipolar?

    Alexander Zhebit

    2003-06-01

    Full Text Available O artigo persegue o objetivo de definir o lugar e o papel da Rússia nas relações internacionais contemporâneas nos últimos anos. Ao se debruçar sobre o dilema tradicional da política externa russa - Ocidentalismo versus Orientalismo - o autor analisa o cenário de multipolaridade defendido pela nova concepção da política externa russa e o relaciona com a fase do pragmatismo e do multilateralismo que caracteriza a atuação internacional da Rússia de Putin, fazendo considerações, decorrentes do impacto dos ataques terroristas aos Estados Unidos em 11 de setembro de 2001 sobre a política externa russa. A atitude pragmática e a natureza multivetorial da política externa russa contribuem, segundo o autor, para o fortalecimento das posições internacionais da Rússia em comparação com a perda ou a natureza incerta das alianças e dos relacionamentos do período da transição pós-soviética.The article pursues the purpose to place Russia and its politics within the context of today's international relations. While discussing the traditional dilemma of the Russian foreign politics - Occidentalism versus Orientalism - the author analyses the scenario of multipolarity, backed up by the new Russian foreign policy concept. Hence it is related to the pragmatism and the multilateralism of the international posture of Putin's Russia, the author makes several considerations, which follow from the impact of the September 11th, 2001, terrorist attacks on the United States of America with regard to Russia's foreign policy. The pragmatic attitude and the multi-axis nature of the Russian foreign policy nowadays contribute, according to the author, to strengthen Russia's international background in comparison with the loss or the uncertain nature of alliances and relationships of the post-Soviet transition period.

  8. Mental Imagery of Speech and Movement Implicates the Dynamics of Internal Forward Models

    DavidPoeppel

    2010-01-01

    The classical concept of efference copies in the context of internal forward models has stimulated productive research in cognitive science and neuroscience. There are compelling reasons to argue for such a mechanism, but finding direct evidence in the human brain remains difficult. Here we investigate the dynamics of internal forward models from an unconventional angle: mental imagery, assessed while recording high temporal resolution neuronal activity using magnetoencephalography (MEG). We ...

  9. Quantifying the dynamics of water bodies, wetlands and biomass in the Poyang Lake region: A multi-polarization SAR remote sensing approach

    Sang, Huiyong

    Field measurements were combined with synthetic aperture radar (SAR) images to evaluate the use of C-band multi-polarized radar remote sensing for estimating plant parameters (plant height, fresh biomass, dry biomass and vegetation water content) of wetland vegetation, and mapping the dynamics of water bodies, wetlands (natural wetlands and rice paddies) and flooding extents in the Poyang Lake region. The capacity of L-band SAR in land cover mapping was also investigated by integrating with optical imagery. Hydrological patterns in Poyang Lake are the dominant factor controlling the spatial and temporal variations of wetland species in Poyang Lake. Water levels in this region are primarily governed by five rivers (Ganjiang river, Xiushui river, Raohe river, Fuhe river, and Xinjiang river). Its northern region is also influenced by the backflow from Yangtze River. The above-ground total biomass increased steadily from March following the hydrological cycle. Wetland species colonizing at different altitudes were gradually flooded from late spring to summer. Carex spp. died during flooding periods and started another growth cycle in autumn after flooding receded. Canopy volume dominates the radar backscattering mechanism in Carex spp. wetlands during their growth period, but the temporal variation of radar backscatter from these wetlands is mainly influenced by flooding. Tall wetland species (Miscanthus sacchariflorus, Phragmites communis Trin., and others) still emerged above water surfaces during flooding peaks and started to senesce in autumn. Surface backscattering mechanism is dominant during the early growing stage and the senescent period of tall vegetation. Plant canopy variation controlled the temporal dynamics of radar backscatters from Phragmites communis Min. Radar backscattering mechanisms from Miscanthus sacchariflorus wetlands were more complicated during the flooding periods. The variations of ground water depth and plant structure of Miscanthus

  10. Sustainability in a multipolar world

    Basha i Novosejt, A.; Weterings, R.; Ridder, M. de; Frinking, E.

    2010-01-01

    In its 30-Year Update of the well-known publication ‘The Limits to growth’ the Club of Rome stressed that the once debated notion of a physically limited world growth is becoming apparent in many well-documented studies. Three decades ago, the Brundtland Commission on Development and Environment ini

  11. On World Multi-Polarization

    YuSui

    2004-01-01

    After the end of the Cold War, especially after the Bush Jr. government assuming power, the U.S. has actively pursued unilateralism and strengthened the momentum of unipolarity, relying on its position of strength as the only superpower and taking advantage of the fight against terrorism. However, the re-

  12. Sustainability in a multipolar world

    Basha i Novosejt, A.; R. Weterings; de Ridder, M.; Frinking, E.

    2010-01-01

    In its 30-Year Update of the well-known publication ‘The Limits to growth’ the Club of Rome stressed that the once debated notion of a physically limited world growth is becoming apparent in many well-documented studies. Three decades ago, the Brundtland Commission on Development and Environment initiated an international momentum to secure the needs of both present and future generations through a joint policy agenda for sustainable development. Institutions such as the United Nations played...

  13. Functions and structure of nuclear deterrence in the post-cold war world. More for less - an arms control strategy for the 1990s. A SIOP for Perestroika. Theater nuclear forces and extended deterrence in a multipolar world. Special series report

    Snow, D.M.; Wooten, R.E.; Sundberg, E.E.; Szafranski, R.; Booker, D.L.

    1992-06-01

    This Publication includes: Essay (1). The Function and Structure of Nuclear Deterrence in the Post-Cold War World. Essay (2). More for Less-An Arms Control Strategy for the 1990s. Essay (3). A SIOP for Perestroika. Essay (4). Theater Nuclear Forces and Extended Deterrence in a Multipolar World.

  14. Evaluation of the solid state dipole moment and pyroelectric coefficient of phosphangulene by multipolar modeling of X-ray structure factors

    Madsen, G.K.H.; Krebs, Frederik C; Lebech, B.; Larsen, F.K.

    2000-01-01

    moment measured in a chloroform solution. It is substantiated that the estimated standard deviation of the dipole moment is about 0.8 D. The standard uncertainty (s.u.) of the derived dipole moment has been derived by splitting the dataset into three independent datasets. A novel method for obtaining...

  15. An intertemporal, multi-region general equilibrium model of agricultural trade liberalization in the South Mediterranean NICs, Turkey, and the European Union

    Bayar, Ali; DIAO, Xinshen; Yeldan, A. Erinc

    2000-01-01

    With the aid of an intertemporal, multi-region general equilibrium model, the authors study issues of agricultural trade liberalization, growth and capital accumulation in the context of a world economy moving towards a multi-polar structure. They specifically focus on Turkey, the European Union, the Middle East, and the Economies in Transition; and study alternative scenarios of formation of customs unions and increased trade orientation. The model is based on intertemporal general equilibri...

  16. Experimental Study on Multi-Band and Multi-Polarization Characteristics of Sea Clutter%多波段多极化海杂波特性的实验研究

    康士峰; 葛德彪; 罗贤云; 张忠治

    2000-01-01

    It is well known that the study of sea clutter characteristics is very important for radar and microwave remote sensing. The multi-band (S, C, X, Ku ) and multi-polarization characteristics of sea clutter measured based on the vector metwork analyzer HP8720C are described in this paper. The measureing system, experimental description and methods of data processing are included. The relationship between clutter characteristics (scatter coefficent, doppler spectrum) and frequency, polarization incident angle (including low-grazing angle) are obtained and some typical results are given.%长期以来,海杂波特性研究一直是雷达和微波遥感界普遍关心的问题。本文讨论基于矢量网络分析仪组建的波谱计对海杂波特性所进行的多波段(S,C,X,Ku)多极化测量,包括测量系统、实验描述和数据处理方法,通过数据分析得到不同海态下杂波特性(散射系数、多普勒谱等)随频率、极化和人射角(含小擦地角)的变化关系并给出一些典型结果。

  17. Clinical applications of magnetoencephalography in epilepsy

    Ray Amit

    2010-01-01

    Full Text Available Magnetoencehalography (MEG is being used with increased frequency in the pre-surgical evaluation of patients with epilepsy. One of the major advantages of this technique over the EEG is the lack of distortion of MEG signals by the skull and intervening soft tissue. In addition, the MEG preferentially records activity from tangential sources thus recording activity predominantly from sulci, which is not contaminated by activity from apical gyral (radial sources. While the MEG is probably more sensitive than the EEG in detecting inter-ictal spikes, especially in the some locations such as the superficial frontal cortex and the lateral temporal neocortex, both techniques are usually complementary to each other. The diagnostic accuracy of MEG source localization is usually better as compared to scalp EEG localization. Functional localization of eloquent cortex is another major application of the MEG. The combination of high spatial and temporal resolution of this technique makes it an extremely helpful tool for accurate localization of visual, somatosensory and auditory cortices as well as complex cognitive functions like language. Potential future applications include lateralization of memory function.

  18. The african protoproverbial in a multipolar world

    Taiwo, Ọlọruntọba-Oju

    2014-01-01

    The proverb is a rhetorical universal and as such shares features across linguistic, ethnic and culture boundaries, thus making typological distinctions along ethnic or regional lines a daunting task. Further complicating this scenario within the African context is the relentless hybridization and subversion of the African proverb consequent on colonial contact and sundry postcolonial interventions. This twin trajectory, the conceptual universalism of the proverb and the relent...

  19. Asian century or multi-polar century ?

    Dollar, David

    2007-01-01

    The "rise of Asia" is something of a myth. During 1990-2005 China accounted for 28 percent of global growth, measured at purchasing power parity (PPP). India accounted for 9 percent. The rest of developing Asia, with nearly a billion people, accounted for only 7 percent, the same as Latin America. Hence there is no general success of Asian developing economies. China has grown better than ...

  20. Latin American regionalism in a multipolar world

    Garzón, Jorge F.

    2015-01-01

    The landscape of Latin American regionalism has experienced profound transformations in a relatively short period of time. Regional organizations have proliferated; the open regionalism of the 1990s has gone into decay; new organizations, often referred to as belonging to a new wave of a more political “posthegemonic regionalism,” took center stage; only to be displaced in the attention of observers by newer trade-oriented organizations such as the Pacific Alliance. These developments have be...

  1. 抑郁症住院患者静息态的脑磁频谱分析%A magnetoencephalography analysis of resting state power spectrum of inpatients with major depressive disorder

    汤浩; 卢青; 韩莉; 江海腾; 罗国平; 姚志剑

    2012-01-01

    Objective To explore the discrepancies of magnetoencephalography (MEG) spectral power between female patients with major depressive disorder and nondepressed subjects in resting state.Methods Whole head MEG recordings were obtained in 12 female patients with major depressive disorder and 12 age-and education-matched nondepressed control subjects in resting state condition with eyes closed.Each region's mean power in delta,theta,alpha,beta frequency bands was calculated through power normalization.Discrepancies between groups were obtained by two sample t-test using MATLAB 7.8.Results The power of alpha and beta frequency bands in patients was increased relative to controls,the abnormal brain regions were separately shown as follows:the alpha frequency band in the right parietal lobe (0.031 vs.0.017; t =1.911,P =0.035),the beta frequency band in the left parietal lobe (0.025vs.0.015;t =2.504,P=0.010),the right parietal lobe(0.026 vs.0.016;t =2.063,P =0.026),the left occipital lobe(0.054 vs.0.029 ; t =3.000,P =0.003) and the right occipital lobe (0.046 vs.0.032 ; t =2.035,P =0.027).The power of delta and theta frequency bands was decreased in patients relative to controls,the abnormal brain regions were separately shown as follows:the delta frequency band in the left occipital lobe (0.029 vs.0.049 ; t =-1.788,P =0.044) ; the theta frequency band in the right central region(0.005 vs.0.012;t =-1.820,P =0.041) and the right temporal lobe(0.015 vs.0.023;t =-1.934,P =0.033).Conclusions The discrepancies of spectral power show a prevalence in posterior brain areas involving delta,theta,alpha and beta frequency bands in depressed patients in comparison with nondepressed comparison subjects.%目的 探讨抑郁症患者与正常对照静息态脑磁频谱分布特征的差异.方法 12例女性抑郁症患者(患者组)和12名年龄、受教育程度相匹配的女性健康对照者(对照组)接受脑磁图静息态扫描,通过频谱分析计算delta、theta、alpha

  2. Detailed magnetic model simulations of the H- injection chicane magnets for the CERN PS Booster Upgrade, including eddy currents and influence on beam dynamics

    Benedetto, E; Borburgh, J; Carli, C; Martini, M; Forte, V

    2014-01-01

    The CERN PS Booster will be upgraded with an H- injection system. The chicanemagnets for the injection bump ramp-down in 5 ms and generate eddy currents in the inconel vacuum chamber which perturb the homogeneity of the magnetic field. The multipolar field components are extracted from 3D OPERA simulations and are included in the lattice model. The -beating correction is computed all along the ramp and complete tracking simulations including space-charge are performed to evaluate the impact of these perturbations and correction on beam dynamics.

  3. Nuclear transition matrix elements for Majoron-accompanied neutrinoless double-β decay within a projected-Hartree-Fock-Bogoliubov model

    Rath, P. K.; Chandra, R.; Chaturvedi, K.; Lohani, P.; Raina, P. K.

    2016-02-01

    The model-dependent uncertainties in the nuclear transition matrix elements for the Majoron-accompanied neutrinoless double-β decay (0+→0+transition) of Zr,9694, 100Mo, Te,130128, and 150Nd isotopes are calculated by employing the projected-Hartree-Fock-Bogoliubov formalism with four different parametrizations of the pairing plus multipolar two-body interactions and three different parametrizations of the Jastrow short-range correlations. Uncertainties in the nuclear transition matrix elements turn out to be less than 15% and 21% for decays involving the emission of single and double Majorons, respectively.

  4. Transfer entropy--a model-free measure of effective connectivity for the neurosciences.

    Vicente, Raul; Wibral, Michael; Lindner, Michael; Pipa, Gordon

    2011-02-01

    Understanding causal relationships, or effective connectivity, between parts of the brain is of utmost importance because a large part of the brain's activity is thought to be internally generated and, hence, quantifying stimulus response relationships alone does not fully describe brain dynamics. Past efforts to determine effective connectivity mostly relied on model based approaches such as Granger causality or dynamic causal modeling. Transfer entropy (TE) is an alternative measure of effective connectivity based on information theory. TE does not require a model of the interaction and is inherently non-linear. We investigated the applicability of TE as a metric in a test for effective connectivity to electrophysiological data based on simulations and magnetoencephalography (MEG) recordings in a simple motor task. In particular, we demonstrate that TE improved the detectability of effective connectivity for non-linear interactions, and for sensor level MEG signals where linear methods are hampered by signal-cross-talk due to volume conduction. PMID:20706781

  5. Giant resonance of electrical multipole from droplet model

    The formalism of the electrical multipole resonance developed from the Droplet nuclear model is presented. It combines the approaches of Goldhaber-Teller (GT) and Steinwedel-Jensen (SJ) and it shows the relative contribution of Coulomb, superficial and neutron excess energies. It also discusses the calculation of half-width. The model evaluates correctly the resonance energies as a function of nuclear mass and allows, through the Mixture Index, the prediction of the complementary participation of modes SJ and GT in the giant nuclear resonance. Values of the mixture index, for each multipolarity, reproduce well the form factors obtained from experiments of charged particle inelastic scattering. The formalism presented for the calculation of the half-width gives a macroscopic description of the friction mechanism. The establishment of the macroscopic structure of the Dissipation Function is used as a reference in the comparison of microscopic calculations. (Author)

  6. Modelling the dispersion energy for Van der Waals complexes

    Sanz-Garcia, A

    2002-01-01

    Strictly ab initio calculations of the dispersion energy are unfeasible in practice but for the smallest systems. A sensible alternative is to model the dispersion contribution through a damped multipolar expansion. This thesis proposes to represent the dispersion energy by means of a non-empirical, atom-atom model using damping functions scaled from 'exact' results for one electron-one electron systems. We start by investigating the scalability of ab initio calculated damping functions for closed-shell atom-atom dimers. Ab initio scaling parameters are employed to assess the quality of the damping functions yielded by a predictor scheme based on the charge overlap between the interacting monomers. The investigation of the scaling properties is extended to atom-linear molecule systems, focusing on the dependence on orientation of the short-range dispersion energy and how to account for it using isotropic damping parameters. We study the possibilities of an 'atomic' (multicentre) representation of the dispersi...

  7. Charged patchy particle models in explicit salt: Ion distributions, electrostatic potentials, and effective interactions

    We introduce a set of charged patchy particle models (CPPMs) in order to systematically study the influence of electrostatic charge patchiness and multipolarity on macromolecular interactions by means of implicit-solvent, explicit-ion Langevin dynamics simulations employing the Gromacs software. We consider well-defined zero-, one-, and two-patched spherical globules each of the same net charge and (nanometer) size which are composed of discrete atoms. The studied mono- and multipole moments of the CPPMs are comparable to those of globular proteins with similar size. We first characterize ion distributions and electrostatic potentials around a single CPPM. Although angle-resolved radial distribution functions reveal the expected local accumulation and depletion of counter- and co-ions around the patches, respectively, the orientation-averaged electrostatic potential shows only a small variation among the various CPPMs due to space charge cancellations. Furthermore, we study the orientation-averaged potential of mean force (PMF), the number of accumulated ions on the patches, as well as the CPPM orientations along the center-to-center distance of a pair of CPPMs. We compare the PMFs to the classical Derjaguin-Verwey-Landau-Overbeek theory and previously introduced orientation-averaged Debye-Hückel pair potentials including dipolar interactions. Our simulations confirm the adequacy of the theories in their respective regimes of validity, while low salt concentrations and large multipolar interactions remain a challenge for tractable theoretical descriptions

  8. Charged patchy particle models in explicit salt: Ion distributions, electrostatic potentials, and effective interactions

    Yigit, Cemil; Dzubiella, Joachim, E-mail: joachim.dzubiella@helmholtz-berlin.de [Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, 14109 Berlin (Germany); Helmholtz Virtual Institute “Multifunctional Biomaterials for Medicine,” 14513 Teltow (Germany); Institut für Physik, Humboldt-Universität zu Berlin, 12489 Berlin (Germany); Heyda, Jan [Department of Physical Chemistry, University of Chemistry and Technology, Prague, 166 28 Praha 6 (Czech Republic)

    2015-08-14

    We introduce a set of charged patchy particle models (CPPMs) in order to systematically study the influence of electrostatic charge patchiness and multipolarity on macromolecular interactions by means of implicit-solvent, explicit-ion Langevin dynamics simulations employing the Gromacs software. We consider well-defined zero-, one-, and two-patched spherical globules each of the same net charge and (nanometer) size which are composed of discrete atoms. The studied mono- and multipole moments of the CPPMs are comparable to those of globular proteins with similar size. We first characterize ion distributions and electrostatic potentials around a single CPPM. Although angle-resolved radial distribution functions reveal the expected local accumulation and depletion of counter- and co-ions around the patches, respectively, the orientation-averaged electrostatic potential shows only a small variation among the various CPPMs due to space charge cancellations. Furthermore, we study the orientation-averaged potential of mean force (PMF), the number of accumulated ions on the patches, as well as the CPPM orientations along the center-to-center distance of a pair of CPPMs. We compare the PMFs to the classical Derjaguin-Verwey-Landau-Overbeek theory and previously introduced orientation-averaged Debye-Hückel pair potentials including dipolar interactions. Our simulations confirm the adequacy of the theories in their respective regimes of validity, while low salt concentrations and large multipolar interactions remain a challenge for tractable theoretical descriptions.

  9. Pitfalls in the dipolar model for the neocortical EEG sources.

    Riera, Jorge J; Ogawa, Takeshi; Goto, Takakuni; Sumiyoshi, Akira; Nonaka, Hiroi; Evans, Alan; Miyakawa, Hiroyoshi; Kawashima, Ryuta

    2012-08-01

    For about six decades, primary current sources of the electroencephalogram (EEG) have been assumed dipolar in nature. In this study, we used electrophysiological recordings from anesthetized Wistar rats undergoing repeated whisker deflections to revise the biophysical foundations of the EEG dipolar model. In a first experiment, we performed three-dimensional recordings of extracellular potentials from a large portion of the barrel field to estimate intracortical multipolar moments generated either by single spiking neurons (i.e., pyramidal cells, PC; spiny stellate cells, SS) or by populations of them while experiencing synchronized postsynaptic potentials. As expected, backpropagating spikes along PC dendrites caused dipolar field components larger in the direction perpendicular to the cortical surface (49.7 ± 22.0 nA·mm). In agreement with the fact that SS cells have "close-field" configurations, their dipolar moment at any direction was negligible. Surprisingly, monopolar field components were detectable both at the level of single units (i.e., -11.7 ± 3.4 nA for PC) and at the mesoscopic level of mixed neuronal populations receiving extended synaptic inputs within either a cortical column (-0.44 ± 0.20 μA) or a 2.5-m(3)-voxel volume (-3.32 ± 1.20 μA). To evaluate the relationship between the macroscopically defined EEG equivalent dipole and the mesoscopic intracortical multipolar moments, we performed concurrent recordings of high-resolution skull EEG and laminar local field potentials. From this second experiment, we estimated the time-varying EEG equivalent dipole for the entire barrel field using either a multiple dipole fitting or a distributed type of EEG inverse solution. We demonstrated that mesoscopic multipolar components are altogether absorbed by any equivalent dipole in both types of inverse solutions. We conclude that the primary current sources of the EEG in the neocortex of rodents are not precisely represented by a single equivalent

  10. Low frequency overactivation in dyslexia: Evidence from resting state Magnetoencephalography.

    Pagnotta, Mattia F; Zouridakis, George; Lianyang Li; Lizarazu, Mikel; Lallier, Marie; Molinaro, Nicola; Carreiras, Manuel

    2015-08-01

    In this study, we compared the brain activation profiles obtained from resting state Magnetoencephalographic (MEG) activity in 15 dyslexic patients with the profiles of 15 normal controls, using power spectral density (PSD) analysis. We first estimated intracranial dipolar MEG sources on a dense grid on the cortical surface and then projected these sources on a standardized atlas with 68 regions of interest (ROIs). Averaging the PSD values of all sources in each ROI across all control subjects resulted in a normative database that was used to convert the PSD values of dyslexic patients into z-scores in eight distinct frequency bands. We found that dyslexic patients exhibited statistically significant overactivation in the delta band (0.1-4 Hz) in the right temporal (entorhinal and insula), left inferior frontal (Broca's area), and right inferior frontal regions. Overactivation may be interpreted as a compensatory mechanism for reading characterizing dyslexic patients. These findings suggest that resting-state MEG activation maps may be used as specific biomarkers that can help with the diagnosis of and assess the efficacy of intervention in dyslexia. PMID:26737893

  11. Noise cancellation in magnetoencephalography and electroencephalography with isolated reference sensors

    Kraus, Jr., Robert H.; Espy, Michelle A.; Matlachov, Andrei; Volegov, Petr

    2010-06-01

    An apparatus measures electromagnetic signals from a weak signal source. A plurality of primary sensors is placed in functional proximity to the weak signal source with an electromagnetic field isolation surface arranged adjacent the primary sensors and between the weak signal source and sources of ambient noise. A plurality of reference sensors is placed adjacent the electromagnetic field isolation surface and arranged between the electromagnetic isolation surface and sources of ambient noise.

  12. Distorted cortical networks in dislexia: findings using Magnetoencephalography (MEG

    Eduardo M. Catillo

    2008-04-01

    Full Text Available In dyslexic children a functional deficit in the brain circuitry supporting some of the cognitive operations taking place while they learn how the printed words maps onto spoken language is suspected. Until recently, however, no information existed regarding the functional status of this circuit during the early stages of reading acquisition. In the context of three studies we sought to address key issues in the pathophysiology of this condition using Magnetoencephalograhy (MEG at the University of Texas-Houston. The first study, including 30 kindergarten children at risk for developing reading problems and 15 not-at-risk controls, ascertained that the aberrant neural circuit that underlies reading problems appears to be present in the initial stages of reading acquisition. A subset of these children were retested a year later using identical procedures in a second study. Children in the at-risk group showed the most prominent changes in brain activation profiles and successfully predicted individual differences in the growth of reading skill measures. The results of a third study showed clearly that the aberrant activation profile can be normalized following intensive behavioral instruction. These findings are consistent with the view that dyslexia represents a functional deficit in the neural network that mediates the conversion of print to sound, which is amenable to change given adequate instruction.

  13. Phase-compensated averaging for analyzing electroencephalography and magnetoencephalography epochs.

    Matani, Ayumu; Naruse, Yasushi; Terazono, Yasushi; Iwasaki, Taro; Fujimaki, Norio; Murata, Tsutomu

    2010-05-01

    Stimulus-locked averaging for electroencephalography and/or megnetoencephalography (EEG/MEG) epochs cancels out ongoing spontaneous activities by treating them as noise. However, such spontaneous activities are the object of interest for EEG/MEG researchers who study phase-related phenomena, e.g., long-distance synchronization, phase-reset, and event-related synchronization/desynchronization (ERD/ERS). We propose a complex-weighted averaging method, called phase-compensated averaging, to investigate phase-related phenomena. In this method, any EEG/MEG channel is used as a trigger for averaging by setting the instantaneous phases at the trigger timings to 0 so that cross-channel averages are obtained. First, we evaluated the fundamental characteristics of this method by performing simulations. The results showed that this method could selectively average ongoing spontaneous activity phase-locked in each channel; that is, it evaluates the directional phase-synchronizing relationship between channels. We then analyzed flash evoked potentials. This method clarified the directional phase-synchronizing relationship from the frontal to occipital channels and recovered another piece of information, perhaps regarding the sequence of experiments, which is lost when using only conventional averaging. This method can also be used to reconstruct EEG/MEG time series to visualize long-distance synchronization and phase-reset directly, and on the basis of the potentials, ERS/ERD can be explained as a side effect of phase-reset. PMID:20172813

  14. Magnetoencephalography evidence for different brain subregions serving two musical cultures

    MATSUNAGA, Rie; Yokosawa, Koichi; Abe, Jun-ichi

    2012-01-01

    Individuals who have been exposed to two different musical cultures (bimusicals) can be differentiated from those exposed to only one musical culture (monomusicals). Just as bilingual speakers handle the distinct language-syntactic rules of each of two languages, bimusical listeners handle two distinct musical-syntactic rules (e.g., tonal schemas) in each musical culture. This study sought to determine specific brain activities that contribute to differentiating two culture-specific tonal str...

  15. New modes of nuclear excitations in microscopic and collective model description

    A microscopic approach based on density functional theory and multi-phonon QRPA methods is successfully applied for investigations of pygmy resonances and other excitations of different multipolarities and energies in stable and exotic nuclei. From systematic studies of nuclear response functions a clear indication of close connection between low-energy excited states related to pygmy resonances and nuclear skin oscillations is observed. This is confirmed also in analyses of transition densities and currents. A useful link to collective model approaches is used for distinction of pygmy resonance from other modes of excitations related low-energy multi-phonon vibrations, twist modes or giant resonances observed in response functions and data. Furthermore, nuclear skins are found to affect M1 strength distributions in nuclei, as confirmed by recent experiments. The fine structure of the spin-flip M1 resonance is discussed and compared to experimental data.

  16. New modes of nuclear excitations in microscopic and collective model description

    Tsoneva, Nadia [Institut fuer Theoretische Physik, Universitaet Giessen (Germany); INRNE, BAS, Sofia (Bulgaria); Lenske, Horst [Institut fuer Theoretische Physik, Universitaet Giessen (Germany)

    2013-07-01

    A microscopic approach based on density functional theory and multi-phonon QRPA methods is successfully applied for investigations of pygmy resonances and other excitations of different multipolarities and energies in stable and exotic nuclei. From systematic studies of nuclear response functions a clear indication of close connection between low-energy excited states related to pygmy resonances and nuclear skin oscillations is observed. This is confirmed also in analyses of transition densities and currents. A useful link to collective model approaches is used for distinction of pygmy resonance from other modes of excitations related low-energy multi-phonon vibrations, twist modes or giant resonances observed in response functions and data. Furthermore, nuclear skins are found to affect M1 strength distributions in nuclei, as confirmed by recent experiments. The fine structure of the spin-flip M1 resonance is discussed and compared to experimental data.

  17. Towards a multipolar science world: Trends and impact

    Veugelers, Reinhilde

    2010-01-01

    This paper brings together recent statistical evidence on international (co-)publications and (foreign) PhD-students and scholars to document shifts in geographic sources of scientific production and their impact. The evidence demonstrates that despite the continued dominance of the US and the increasing importance of the EU, the TRIAD is in relative decline. Other geographic sources of science outside the TRIAD are rising, both in quantity, but also, although still to a lesser extent, in qua...

  18. The filamentary Multi-Polar Planetary Nebula NGC 5189

    Sabin, L; López, J A; García-Díaz, Ma T; Ramos-Larios, G

    2012-01-01

    We present a set of optical and infrared images combined with long-slit, medium and high dispersion spectra of the southern planetary nebula (PN) NGC 5189. The complex morphology of this PN is puzzling and has not been studied in detail so far. Our investigation reveals the presence of a new dense and cold infrared torus (alongside the optical one) which probably generated one of the two optically seen bipolar outflows and which might be responsible for the twisted appearance of the optical torus via an interaction process. The high-resolution MES-AAT spectra clearly show the presence of filamentary and knotty structures as well as three expanding bubbles. Our findings therefore suggest that NGC 5189 is a quadrupolar nebula with multiple sets of symmetrical condensations in which the interaction of outflows has determined the complex morphology.

  19. THE FILAMENTARY MULTI-POLAR PLANETARY NEBULA NGC5189

    L. Sabin

    2012-01-01

    Full Text Available We present a set of optical and infrared images combined with long-slit, medium and high dispersion spectra of the southern planetary nebula (PN NGC5189. The complex morphology of this PN is puzzling and has not been studied in detailed so far. Our investigation reveals the presence of a new dense and cold infrared torus (alongside the optical one which probably generated one of the two optically seen bipolar outflows and which might be responsible for the twisted appearance of the optical torus via an interaction process. The high-resolution MES-AAT spectra clearly show the presence of filamentary and knotty structures as well as three expanding bubbles. Our findings therefore suggest that NGC5189 is a quadrupolar nebula with multiple sets of symmetrical condensations in which the interaction of outflows has determined its complex morphology.

  20. GEOPOLITICAL STRATEGIES AND MODERNITY: MULTIPOLAR WORLD OF NOWADAYS

    Radenko Scekic

    2016-01-01

    Full Text Available The political map of the planet has transformed substantially during the last century. Former colonial powers had to be satisfied with the perfidious forms of political and economic control. The last decades were marked by the global dominance of the US and its allies, as well as the military superiority of the NATO pact. The beginning of the new millennium was filled with military and financial crises. On the global stage have appeared new economic and military powers and organizations such as the BRICS, the Eurasian Union, the economic power of China, and Russia's comeback in the geopolitical games. The former geopolitical theories become topical again.

  1. Controversies over the US Hegemony in the Multipolar World

    Gwiazda, Adam

    2010-01-01

    Since the end of the Cold War, American hegemony continues to characterize the international system. This hegemony has met with a considerably higher acceptance by other states and other actors of the international system than a world of competing superpowers and political blocs. The main argument developed in this paper is that American primacy may not last forever, but as there is no effective global security mechanism for coping with the growing threat of extremist religious and political ...

  2. Models

    Juel-Christiansen, Carsten

    2005-01-01

    Artiklen fremhæver den visuelle rotation - billeder, tegninger, modeller, værker - som det privilligerede medium i kommunikationen af ideer imellem skabende arkitekter......Artiklen fremhæver den visuelle rotation - billeder, tegninger, modeller, værker - som det privilligerede medium i kommunikationen af ideer imellem skabende arkitekter...

  3. Modelling

    Spädtke, P

    2013-01-01

    Modeling of technical machines became a standard technique since computer became powerful enough to handle the amount of data relevant to the specific system. Simulation of an existing physical device requires the knowledge of all relevant quantities. Electric fields given by the surrounding boundary as well as magnetic fields caused by coils or permanent magnets have to be known. Internal sources for both fields are sometimes taken into account, such as space charge forces or the internal magnetic field of a moving bunch of charged particles. Used solver routines are briefly described and some bench-marking is shown to estimate necessary computing times for different problems. Different types of charged particle sources will be shown together with a suitable model to describe the physical model. Electron guns are covered as well as different ion sources (volume ion sources, laser ion sources, Penning ion sources, electron resonance ion sources, and H$^-$-sources) together with some remarks on beam transport.

  4. Modelling

    This last volume in the series of textbooks on environmental isotopes in the hydrological cycle provides an overview of the basic principles of existing conceptual formulations of modelling approaches. While some of the concepts provided in Chapter 2 and Chapter 3 are of general validity for quantitative interpretation of isotope data; the modelling methodologies commonly employed for incorporating isotope data into evaluations specifically related to groundwater systems are given in this volume together with some illustrative examples. Development of conceptual models for quantitative interpretations of isotope data in hydrogeology and the assessment of their limitations and field verification has been given priority in the research and development efforts of the IAEA during the last decade. Several Co-ordinated Research Projects on this specific topic were implemented and results published by the IAEA. Based on these efforts and contributions made by a number of scientists involved in this specific field, the IAEA has published two Technical Documents entitled ''Mathematical models and their applications to isotope studies in groundwater studies -- IAEA TECDOC-777, 1994'' and ''Manual on Mathematical models in isotope hydrogeology -- IAEA TECDOC-910, 1996''. Results of a recently completed Co-ordinated Research Project by the IAEA entitled ''Use of isotopes for analysis of flow and transport dynamics in groundwater systems'' will also soon be published by the IAEA. This is the reason why the IAEA was involved in the co-ordination required for preparation of this volume; the material presented is a condensed overview prepared by some of the scientists that were involved in the above cited IAEA activities. This volume VI providing such an overview was included into the series to make this series self-sufficient in its coverage of the field of Isotope Hydrology. A special chapter on the methodologies and concepts related to geochemical modelling in groundwater

  5. Mental imagery of speech and movement implicates the dynamics of internal forward models

    Xing eTian

    2010-10-01

    Full Text Available The classical concept of efference copies in the context of internal forward models has stimulated productive research in cognitive science and neuroscience. There are compelling reasons to argue for such a mechanism, but finding direct evidence in the human brain remains difficult. Here we investigate the dynamics of internal forward models from an unconventional angle: mental imagery, assessed while recording high temporal resolution neuronal activity using magnetoencephalography (MEG. We compare two overt and covert tasks; our covert, mental imagery tasks are unconfounded by overt input/output demands – but in turn necessitate the development of appropriate multi-dimensional topographic analyses. Finger tapping (studies 1-2 and speech experiments (studies 3-5 provide temporally constrained results that implicate the estimation of an efference copy. We suggest that one internal forward model over parietal cortex subserves the kinesthetic feeling in motor imagery. Secondly, observed auditory neural activity ~170 ms after motor estimation in speech experiments (studies 3-5 demonstrates the anticipated auditory consequences of planned motor commands in a second internal forward model in imagery of speech production. Our results provide neurophysiological evidence from the human brain in favor of internal forward models deploying efference copies in somatosensory and auditory cortex, in finger tapping and speech production tasks, respectively, and also suggest the dynamics and sequential updating structure of internal forward models.

  6. Neuronal-like differentiation of bone marrow-derived mesenchymal stem cells induced by striatal extracts from a rat model of Parkinson's disease

    Xiaoling Qin; Wang Han; Zhigang Yu

    2012-01-01

    A rat model of Parkinson's disease was established by 6-hydroxydopamine injection into the medial forebrain bundle. Bone marrow-derived mesenchymal stem cells (BMSCs) were isolated from the femur and tibia, and were co-cultured with 10% and 60% lesioned or intact striatal extracts. The results showed that when exposed to lesioned striatal extracts, BMSCs developed bipolar or multi-polar morphologies, and there was an increase in the percentage of cells that expressed glial fibrillary acidic protein (GFAP), nestin and neuron-specific enolase (NSE). Moreover, the percentage of NSE-positive cells increased with increasing concentrations of lesioned striatal extracts. However, intact striatal extracts only increased the percentage of GFAP-positive cells. The findings suggest that striatal extracts from Parkinson's disease rats induce BMSCs to differentiate into neuronal-like cells in vitro.

  7. Analysis of slow-onset neurite formation in NG108-15 cells: implications for a unified model of neurite elongation.

    Smalheiser, N R

    1989-01-01

    When undifferentiated NG108-15 cells are plated onto polylysine coated Petri dishes in serum-free medium, they form neurites within 1-4 h if plated in the presence of laminin or 5'-deoxy-5'-methylthioadenosine (rapid-onset neurites). In the absence of such agents, serum-deprived NG108-15 cells extend axon-like neurites onto polylysine over several days; here we characterize the dynamic behavior of this slow-onset outgrowth pattern in detail. Individual cells plated on laminin expressed a gradual multipolar-to-unipolar transition due to rapid-onset neurites becoming remodelled into the appearance of slow-onset neurites. This phenomenon reflected the selective stabilization of certain rapid-onset neurites, along with the restriction of motility to their distal tips. Based upon the properties and interactions of both rapid- and slow-onset neurites in NG108-15 cells, a unified model for neurite formation is presented. PMID:2917412

  8. A Novel Method for Integrating MEG and BOLD fMRI Signals With the Linear Convolution Model in Human Primary Somatosensory Cortex

    Nangini, Cathy; Tam, Fred; Graham, Simon J.

    2016-01-01

    Characterizing the neurovascular coupling between hemodynamic signals and their neural origins is crucial to functional neuroimaging research, even more so as new methods become available for integrating results from different functional neuroimaging modalities. We present a novel method to relate magnetoencephalography (MEG) and BOLD fMRI data from primary somatosensory cortex within the context of the linear convolution model. This model, which relates neural activity to BOLD signal change, has been widely used to predict BOLD signals but typically lacks experimentally derived measurements of neural activity. In this study, an fMRI experiment is performed using variable-duration (≤1 s) vibrotactile stimuli applied at 22 Hz, analogous to a previously published MEG study (Nangini et al., [2006]: Neuroimage 33:252–262), testing whether MEG source waveforms from the previous study can inform the convolution model and improve BOLD signal estimates across all stimulus durations. The typical formulation of the convolution model in which the input is given by the stimulus profile is referred to as Model 1. Model 2 is based on an energy argument relating metabolic demand to the postsynaptic currents largely responsible for the MEG current dipoles, and uses the energy density of the estimated MEG source waveforms as input to the convolution model. It is shown that Model 2 improves the BOLD signal estimates compared to Model 1 under the experimental conditions implemented, suggesting that MEG energy density can be a useful index of hemodynamic activity. PMID:17290370

  9. A simple model of the chaotic eccentricity of Mercury

    Boué, Gwenaël; Farago, François

    2012-01-01

    Mercury's eccentricity is chaotic and can increase so much that collisions with Venus or the Sun become possible (Laskar, 1989, 1990, 1994, 2008, Batygin & Laughlin, 2008, Laskar & Gastineau, 2009). This chaotic behavior results from an intricate network of secular resonances, but in this paper, we show that a simple integrable model with only one degree of freedom is actually able to reproduce the large variations in Mercury's eccentricity, with the correct amplitude and timescale. We show that this behavior occurs in the vicinity of the separatrices of the resonance g1-g5 between the precession frequencies of Mercury and Jupiter. However, the main contribution does not come from the direct interaction between these two planets. It is due to the excitation of Venus' orbit at Jupiter's precession frequency g5. We use a multipolar model that is not expanded with respect to Mercury's eccentricity, but because of the proximity of Mercury and Venus, the Hamiltonian is expanded up to order 20 and more in t...

  10. Multi-area neural mass modeling of EEG and MEG signals.

    Babajani-Feremi, Abbas; Soltanian-Zadeh, Hamid

    2010-09-01

    We previously proposed an integrated electroencephalography (EEG), magnetoencephalography (MEG), and functional Magnetic Resonance Imaging (fMRI) model based on an extended neural mass model (ENMM) within a single cortical area. In the ENMM, a cortical area contains several minicolumns where strengths of their connections diminish exponentially with their distances. The ENMM was derived based on the physiological principles of the cortical minicolumns and their connections within a single cortical area to generate EEG, MEG, and fMRI signals. The purpose of this paper is to further extend the ENMM model from a single-area to a multi-area model to develop a neural mass model of the entire brain that generates EEG and MEG signals. For multi-area modeling, two connection types are considered: short-range connections (SRCs) and long-range connections (LRCs). The intra-area SRCs among the minicolumns within the areas were previously modeled in the ENMM. To define inter-area LRCs among the cortical areas, we consider that the cell populations of all minicolumns in the destination area are affected by the excitatory afferent of the pyramidal cells of all minicolumns in the source area. The state-space representation of the multi-area model is derived considering the intra-minicolumn, SRCs', and LRCs' parameters. Using simulations, we evaluate effects of parameters of the model on its dynamics and, based on stability analysis, find valid ranges for parameters of the model. In addition, we evaluate reducing redundancy of the model parameters using simulation results and conclude that the parameters of the model can be limited to the LRCs and SRCs while the intra-minicolumn parameters stay at their physiological mean values. The proposed multi-area integrated E/MEG model provides an efficient neuroimaging technique for effective connectivity analysis in healthy subjects as well as neurological and psychiatric patients. PMID:20080193

  11. A Skew-t space-varying regression model for the spectral analysis of resting state brain activity.

    Ismail, Salimah; Sun, Wenqi; Nathoo, Farouk S; Babul, Arif; Moiseev, Alexader; Beg, Mirza Faisal; Virji-Babul, Naznin

    2013-08-01

    It is known that in many neurological disorders such as Down syndrome, main brain rhythms shift their frequencies slightly, and characterizing the spatial distribution of these shifts is of interest. This article reports on the development of a Skew-t mixed model for the spatial analysis of resting state brain activity in healthy controls and individuals with Down syndrome. Time series of oscillatory brain activity are recorded using magnetoencephalography, and spectral summaries are examined at multiple sensor locations across the scalp. We focus on the mean frequency of the power spectral density, and use space-varying regression to examine associations with age, gender and Down syndrome across several scalp regions. Spatial smoothing priors are incorporated based on a multivariate Markov random field, and the markedly non-Gaussian nature of the spectral response variable is accommodated by the use of a Skew-t distribution. A range of models representing different assumptions on the association structure and response distribution are examined, and we conduct model selection using the deviance information criterion. (1) Our analysis suggests region-specific differences between healthy controls and individuals with Down syndrome, particularly in the left and right temporal regions, and produces smoothed maps indicating the scalp topography of the estimated differences. PMID:22614763

  12. Modeling Modeling

    Muller, Pierre-Alain; Fondement, Frédéric; Baudry, Benoit

    2009-01-01

    Model-driven engineering and model-based approaches have permeated all branches of software engineering; to the point that it seems that we are using models, as Molière's Monsieur Jourdain was using prose, without knowing it. At the heart of modeling, there is a relation that we establish to represent something by something else. In this paper we review various definitions of models and relations between them. Then, we define a canonical set of relations that can be used to express various ki...

  13. Bayesian multi-dipole modelling of a single topography in MEG by adaptive sequential Monte Carlo samplers

    In this paper, we develop a novel Bayesian approach to the problem of estimating neural currents in the brain from a fixed distribution of magnetic field (called topography), measured by magnetoencephalography. Differently from recent studies that describe inversion techniques, such as spatio-temporal regularization/filtering, in which neural dynamics always plays a role, we face here a purely static inverse problem. Neural currents are modelled as an unknown number of current dipoles, whose state space is described in terms of a variable-dimension model. Within the resulting Bayesian framework, we set up a sequential Monte Carlo sampler to explore the posterior distribution. An adaptation technique is employed in order to effectively balance the computational cost and the quality of the sample approximation. Then, both the number and the parameters of the unknown current dipoles are simultaneously estimated. The performance of the method is assessed by means of synthetic data, generated by source configurations containing up to four dipoles. Eventually, we describe the results obtained by analysing data from a real experiment, involving somatosensory evoked fields, and compare them to those provided by three other methods. (paper)

  14. The structure of 193Au within the Interacting Boson Fermion Model

    A γγ angular correlation experiment investigating the nucleus 193Au is presented. In this work the level scheme of 193Au is extended by new level information on spins, multipolarities and newly observed states. The new results are compared with theoretical predictions from a general Interacting Boson Fermion Model (IBFM) calculation for the positive-parity states. The experimental data is in good agreement with an IBFM calculation using all proton orbitals between the shell closures at Z=50 and Z=126. As a dominant contribution of the d3/2 orbital to the wave function of the lowest excited states is observed, a truncated model of the IBFM using a Bose–Fermi symmetry is applied to the describe 193Au. Using the parameters of a fit performed for 193Au, the level scheme of 192Pt, the supersymmetric partner of 193Au, is predicted but shows a too small boson seniority splitting. We obtained a common fit by including states observed in 192Pt. With the new parameters a supersymmetric description of both nuclei is established

  15. Modeling Modeling Modeling

    Muller, Pierre-Alain; Fondement, Frédéric; Baudry, Benoit; Combemale, Benoit

    2012-01-01

    Model-driven engineering and model-based approaches have permeated all branches of software engineering to the point that it seems that we are using models, as Molière's Monsieur Jourdain was using prose, without knowing it. At the heart of modeling, there is a relation that we establish to represent something by something else. In this paper we review various definitions of models and relations between them. Then, we define a canonical set of relations that can be used to express various kin...

  16. Modelling the dispersion energy for Van der Waals complexes

    Strictly ab initio calculations of the dispersion energy are unfeasible in practice but for the smallest systems. A sensible alternative is to model the dispersion contribution through a damped multipolar expansion. This thesis proposes to represent the dispersion energy by means of a non-empirical, atom-atom model using damping functions scaled from 'exact' results for one electron-one electron systems. We start by investigating the scalability of ab initio calculated damping functions for closed-shell atom-atom dimers. Ab initio scaling parameters are employed to assess the quality of the damping functions yielded by a predictor scheme based on the charge overlap between the interacting monomers. The investigation of the scaling properties is extended to atom-linear molecule systems, focusing on the dependence on orientation of the short-range dispersion energy and how to account for it using isotropic damping parameters. We study the possibilities of an 'atomic' (multicentre) representation of the dispersion energy, in contrast to the conventional 'molecular' (single-centre) picture, devising a well-defined method to obtain 'atomic' dispersion coefficients from the computed molecular ones, as well as 'atomic' damping parameters. In all the studied cases, the 'atomic' approach describes more adequately the anisotropy of the interaction, through a localisation process of the charge overlap effects. The CO2/CO case, in particular, encourages to believe in the transferability of 'atomic' dispersion coefficients and damping parameters, which being confirmed by further work, the present results can be regarded as the basis of an universal and affordable model to estimate the dispersion contribution in intermolecular potentials. (author)

  17. GNSS-Reflectometry: Forest canopies polarization scattering properties and modeling

    Wu, Xuerui; Jin, Shuanggen

    2014-09-01

    Nowadays, GNSS-Reflectometry (GNSS-R) can be a new promising remote sensing tool in the ocean, snow/ice and land surfaces, e.g., vegetation biomass monitoring. Although GNSS-R provides a potentially special L-band multi-angular and multi-polarization measurement, the theoretical vegetation scattering properties and mechanisms for GNSS-R are not understood clearly. In this paper, the GNSS-R vegetation polarization scattering properties are studied and modeled at different incidence angles (specular direction). The bistatic scattering model Bi-mimics is employed, which is the first-order radiative transfer equation. As a kind of forest stand, the Aspen’s crown layer is composed of entire leaves, and its parameters in Mimics handbook are used as model input. The specular circular polarizations (co-polarization RR and cross-polarization LR) are simulated. For cross-polarization, the received polarization is assumed as a linear (horizontal and vertical) polarizations and ±45° linear polarizations. Therefore, the HR VR, +45R and -45R polarizations are simulated here. Contributions from different scattering components at RR, LR and VR polarization are also presented. For co-polarization, it is large in the whole specular angles (10-80°). The scattering trends of the other cross polarization (HR, LR, +45R and -45R) are a little similar when compared to the RR and RV. Therefore, the RHCP and V polarizations are more favorable to collect the reflected signals. The trunk heights and crown depths do not affect the scattering trends of RR, RV and RL, while the trunk height has some effect on the scattering amplitude of different polarizations. The azimuth angle has more effects on RR, RL and RV scattering, especially in lower than 50°. The observation angles and polarization combinations are extremely important for GNSS-R remote sensing.

  18. Nuclear liquid-drop model and surface-curvature effects

    Nuclear liquid-drop model is revisited and an explicit introduction of the surface-curvature terms is presented. The corresponding parameters of the extended classical energy formula are adjusted to the contemporarily known nuclear binding energies and fission-barrier heights. Using 2766 binding energies of nuclei with Z≥8 and N≥8 it is shown that the performance of the new approach is improved by a factor of about 6, compared to the previously published liquid-drop model results, in terms of the masses (new rms deviation =0.698 MeV) and the fission barriers by a factor of about 3.5 (new rms deviation of the fission barriers of isotopes with Z>70 is B>=0.88 MeV). The role of the nuclear surface-curvature terms and their effects on the description of the experimental quantities are discussed in detail. For comparison, the parameters of the more 'traditional' classical energy expressions are refitted, taking into account the nuclear masses known today and the performances of several variants of the model are compared. The isospin dependence in the new description of the barriers is in a good agreement with the extended Thomas-Fermi approach. It also demonstrates a good qualitative agreement with the fission lifetime systematics tested on the long chain of Fermium isotopes known experimentally. The new approach offers a very high stability in terms of the extrapolation from the narrower range of nuclides to a more extended one--a property of particular interest for the contemporary exotic beam projects: the corresponding properties are illustrated and discussed. The new description of the fission barriers being significantly improved, in particular, the new calculated barriers being lower, flatter, but stiffer against high-multipolarity deformations. The chances for 'extra' stabilization of the hyperdeformed minima at high spin increase, thus calling for the new total energy Strutinsky-type calculations

  19. Ordering and Fluctuation of Quantum Multipoles in CeB6

    The effect of multipolar fluctuations on the quadrupolar phase transition in CeB6 is investigated theoretically. It is shown that the fluctuations become strong and field-dependent, reflecting the competition of coupled multipolar interactions. Some unusual phenomena around the transition in CeB6 are shown to be reasonably explained within the RKKY model. (author)

  20. Triphenylphosphonium Cations of the Diterpenoid Isosteviol: Synthesis and Antimitotic Activity in a Sea Urchin Embryo Model.

    Strobykina, Irina Yu; Belenok, Mayya G; Semenova, Marina N; Semenov, Victor V; Babaev, Vasiliy M; Rizvanov, Ildar Kh; Mironov, Vladimir F; Kataev, Vladimir E

    2015-06-26

    A series of novel triphenylphosphonium (TPP) cations of the diterpenoid isosteviol (1, 16-oxo-ent-beyeran-19-oic acid) have been synthesized and evaluated in an in vivo phenotypic sea urchin embryo assay for antimitotic activity. The TPP moiety was applied as a carrier to provide selective accumulation of a connected compound into mitochondria. When applied to fertilized eggs, the targeted isosteviol TPP conjugates induced mitotic arrest with the formation of aberrant multipolar mitotic spindles, whereas both isosteviol and the methyltriphenylphosphonium cation were inactive. The structure-activity relationship study revealed the essential role of the TPP group for the realization of the isosteviol effect, while the chemical structure and the length of the linker only slightly influenced the antimitotic potency. The results obtained using the sea urchin embryo model suggested that TPP conjugates of isosteviol induced mitotic spindle defects and mitotic arrest presumably by affecting mitochondrial DNA. Since targeting mitochondria is considered as an encouraging strategy for cancer therapy, TPP-isosteviol conjugates may represent promising candidates for further design as anticancer agents. PMID:26042548

  1. An asymmetric jet launching model for the protoplanetary nebula CRL 618

    Velazquez, P F; Raga, A C; Toledo-Roy, J C

    2014-01-01

    We propose an asymmetrical jet ejection mechanism in order to model the mirror symmetry observed in the lobe distribution of some protoplanetary nebulae (pPNe), such as the pPN CRL 618. 3D hydrodynamical simulations of a precessing jet launched from an orbiting source were carried out including an alternation in the ejections of the two outflow lobes, depending on which side of the precessing accretion disk is hit by the accretion column from a Roche lobe-filling binary companion. Both synthetic optical emission maps and position-velocity (PV) diagrams were obtained from the numerical results with the purpose of carrying out a direct comparison with observations. Depending on the observer's point of view, multipolar morphologies are obtained which exhibit a mirror symmetry at large distances from the central source. The obtained lobe sizes and their spatial distribution are in good agreement with the observed morphology of the pPN CRL 618. We also obtain that the kinematic ages of the fingers are similar to t...

  2. Detecting single-trial EEG evoked potential using a wavelet domain linear mixed model: application to error potentials classification

    Spinnato, J.; Roubaud, M.-C.; Burle, B.; Torrésani, B.

    2015-06-01

    Objective. The main goal of this work is to develop a model for multisensor signals, such as magnetoencephalography or electroencephalography (EEG) signals that account for inter-trial variability, suitable for corresponding binary classification problems. An important constraint is that the model be simple enough to handle small size and unbalanced datasets, as often encountered in BCI-type experiments. Approach. The method involves the linear mixed effects statistical model, wavelet transform, and spatial filtering, and aims at the characterization of localized discriminant features in multisensor signals. After discrete wavelet transform and spatial filtering, a projection onto the relevant wavelet and spatial channels subspaces is used for dimension reduction. The projected signals are then decomposed as the sum of a signal of interest (i.e., discriminant) and background noise, using a very simple Gaussian linear mixed model. Main results. Thanks to the simplicity of the model, the corresponding parameter estimation problem is simplified. Robust estimates of class-covariance matrices are obtained from small sample sizes and an effective Bayes plug-in classifier is derived. The approach is applied to the detection of error potentials in multichannel EEG data in a very unbalanced situation (detection of rare events). Classification results prove the relevance of the proposed approach in such a context. Significance. The combination of the linear mixed model, wavelet transform and spatial filtering for EEG classification is, to the best of our knowledge, an original approach, which is proven to be effective. This paper improves upon earlier results on similar problems, and the three main ingredients all play an important role.

  3. A new methodology for automated diagnosis of mild cognitive impairment (MCI) using magnetoencephalography (MEG).

    Amezquita-Sanchez, Juan P; Adeli, Anahita; Adeli, Hojjat

    2016-05-15

    Mild cognitive impairment (MCI) is a cognitive disorder characterized by memory impairment, greater than expected by age. A new methodology is presented to identify MCI patients during a working memory task using MEG signals. The methodology consists of four steps: In step 1, the complete ensemble empirical mode decomposition (CEEMD) is used to decompose the MEG signal into a set of adaptive sub-bands according to its contained frequency information. In step 2, a nonlinear dynamics measure based on permutation entropy (PE) analysis is employed to analyze the sub-bands and detect features to be used for MCI detection. In step 3, an analysis of variation (ANOVA) is used for feature selection. In step 4, the enhanced probabilistic neural network (EPNN) classifier is applied to the selected features to distinguish between MCI and healthy patients. The usefulness and effectiveness of the proposed methodology are validated using the sensed MEG data obtained experimentally from 18 MCI and 19 control patients. PMID:26940603

  4. Tinnitus perception and distress is related to abnormal spontaneous brain activity as measured by magnetoencephalography.

    2005-06-01

    Full Text Available BACKGROUND: The neurophysiological mechanisms underlying tinnitus perception are not well understood. Surprisingly, there have been no group studies comparing abnormalities in ongoing, spontaneous neuronal activity in individuals with and without tinnitus perception. METHODS AND FINDINGS: Here, we show that the spontaneous neuronal activity of a group of individuals with tinnitus (n = 17 is characterised by a marked reduction in alpha (8-12 Hz power together with an enhancement in delta (1.5-4 Hz as compared to a normal hearing control group (n = 16. This pattern was especially pronounced for temporal regions. Moreover, correlations with tinnitus-related distress revealed strong associations with this abnormal spontaneous activity pattern, particularly in right temporal and left frontal areas. Overall, effects were stronger for the alpha than for the delta frequency band. A data stream of 5 min, recorded with a whole-head neuromagnetometer under a resting condition, was sufficient to extract the marked differences. CONCLUSIONS: Despite some limitations, there are arguments that the regional pattern of abnormal spontaneous activity we found could reflect a tinnitus-related cortical network. This finding, which suggests that a neurofeedback approach could reduce the adverse effects of this disturbing condition, could have important implications for the treatment of tinnitus.

  5. Temporal processing of audiovisual stimuli is enhanced in musicians: evidence from magnetoencephalography (MEG.

    Yao Lu

    Full Text Available Numerous studies have demonstrated that the structural and functional differences between professional musicians and non-musicians are not only found within a single modality, but also with regard to multisensory integration. In this study we have combined psychophysical with neurophysiological measurements investigating the processing of non-musical, synchronous or various levels of asynchronous audiovisual events. We hypothesize that long-term multisensory experience alters temporal audiovisual processing already at a non-musical stage. Behaviorally, musicians scored significantly better than non-musicians in judging whether the auditory and visual stimuli were synchronous or asynchronous. At the neural level, the statistical analysis for the audiovisual asynchronous response revealed three clusters of activations including the ACC and the SFG and two bilaterally located activations in IFG and STG in both groups. Musicians, in comparison to the non-musicians, responded to synchronous audiovisual events with enhanced neuronal activity in a broad left posterior temporal region that covers the STG, the insula and the Postcentral Gyrus. Musicians also showed significantly greater activation in the left Cerebellum, when confronted with an audiovisual asynchrony. Taken together, our MEG results form a strong indication that long-term musical training alters the basic audiovisual temporal processing already in an early stage (direct after the auditory N1 wave, while the psychophysical results indicate that musical training may also provide behavioral benefits in the accuracy of the estimates regarding the timing of audiovisual events.

  6. A magnetoencephalography study of functional brain connectivity in childhood, adolescence and adulthood

    Smith, Helen Joanna Fabienne

    2015-01-01

    Functional brain networks are interconnected brain regions that flexibly coordinate their activity to support cognitive demands (Fair et al., 2009). Functional brain connectivity describes a statistical dependency between the activities recorded at spatially distinct brain regions (Friston, 2009). Changes in the pattern of connections and level of activation in functional brain networks are thought to occur across development (Taylor, Donner, & Pang, 2012) but the nature of these changes and ...

  7. Deficits of magnetoencephalography regional power in patients with major depressive disorder:an individual spectral analysis

    汤浩

    2014-01-01

    Objective To explore the discrepancies of individualized frequency and band power between major depressive disorder(MDD)and controls in resting state,and the association of abnormal spectral power with clinical severity of MDD.Methods Whole-head MEG recordings were collected in 19 patients with MDD and 19 non-depressed controls in eye-closed resting state.Individual spectral power of each subject was calculated based on

  8. A magnetoencephalography analysis of resting state power spectrum of inpatients with major depressive disorder

    汤浩

    2013-01-01

    Objective To explore the discrepancies of magne-toencephalography(MEG) spectral power between female patients with major depressive disorder and nondepressed subjects in resting state. Methods Whole head MEG recordings were obtained in 12 female patients with major

  9. The influence of low-grade glioma on resting state oscillatory brain activity: a magnetoencephalography study

    Bosma, I.; Stam, C.; Douw, L.; Bartolomei, F.; Heimans, J.; van Dijk; Postma, T.; Klein, M.; Reijneveld, J.

    2008-01-01

    Purpose: In the present MEG-study, power spectral analysis of oscillatory brain activity was used to compare resting state brain activity in both low-grade glioma (LGG) patients and healthy controls. We hypothesized that LGG patients show local as well as diffuse slowing of resting state brain activity compared to healthy controls and that particularly global slowing correlates with neurocognitive dysfunction. Patient and methods Resting state MEG recordings were obtained from 17 LGG patients...

  10. Cyclic Evolution of Coronal Fields from a Coupled Dynamo Potential-Field Source-Surface Model

    Dikpati, Mausumi; Suresh, Akshaya; Burkepile, Joan

    2016-02-01

    The structure of the Sun's corona varies with the solar-cycle phase, from a near spherical symmetry at solar maximum to an axial dipole at solar minimum. It is widely accepted that the large-scale coronal structure is governed by magnetic fields that are most likely generated by dynamo action in the solar interior. In order to understand the variation in coronal structure, we couple a potential-field source-surface model with a cyclic dynamo model. In this coupled model, the magnetic field inside the convection zone is governed by the dynamo equation; these dynamo-generated fields are extended from the photosphere to the corona using a potential-field source-surface model. Assuming axisymmetry, we take linear combinations of associated Legendre polynomials that match the more complex coronal structures. Choosing images of the global corona from the Mauna Loa Solar Observatory at each Carrington rotation over half a cycle (1986 - 1991), we compute the coefficients of the associated Legendre polynomials up to degree eight and compare with observations. We show that at minimum the dipole term dominates, but it fades as the cycle progresses; higher-order multipolar terms begin to dominate. The amplitudes of these terms are not exactly the same for the two limbs, indicating that there is a longitude dependence. While both the 1986 and the 1996 minimum coronas were dipolar, the minimum in 2008 was unusual, since there was a substantial departure from a dipole. We investigate the physical cause of this departure by including a North-South asymmetry in the surface source of the magnetic fields in our flux-transport dynamo model, and find that this asymmetry could be one of the reasons for departure from the dipole in the 2008 minimum.

  11. Joint EEG/fMRI state space model for the detection of directed interactions in human brains--a simulation study.

    Lenz, Michael; Musso, Mariachristina; Linke, Yannick; Tüscher, Oliver; Timmer, Jens; Weiller, Cornelius; Schelter, Björn

    2011-11-01

    An often addressed challenge in neuroscience research is the assignment of different tasks to specific brain regions. In many cases several brain regions are activated during a single task. Therefore, one is also interested in the temporal evolution of brain activity to infer causal relations between activated brain regions. These causal relations may be described by a directed, task specific network which consists of activated brain regions as vertices and directed edges. The edges describe the causal relations. Inference of the task specific brain network from measurements like electroencephalography (EEG) or functional magnetic resonance imaging (fMRI) is challenging, due to the low spatial resolution of the former and the low temporal resolution of the latter. Here, we present a simulation study investigating a possible combined analysis of simultaneously measured EEG and fMRI data to address the challenge specified above. A nonlinear state space model is used to distinguish between the underlying brain states and the (simulated) EEG/fMRI measurements. We make use of a modified unscented Kalman filter and a corresponding unscented smoother for the estimation of the underlying neural activity. Model parameters are estimated using an expectation-maximization algorithm, which exploits the partial linearity of our model. Inference of the brain network structure is then achieved using directed partial correlation, a measure for Granger causality. The results indicate that the convolution effect of the fMRI forward model imposes a big challenge for the parameter estimation and reduces the influence of the fMRI in combined EEG-fMRI models. It remains to be investigated whether other models or similar combinations of other modalities such as, e.g., EEG and magnetoencephalography can increase the profit of the promising idea of combining various modalities. PMID:22027197

  12. Joint EEG/fMRI state space model for the detection of directed interactions in human brains—a simulation study

    An often addressed challenge in neuroscience research is the assignment of different tasks to specific brain regions. In many cases several brain regions are activated during a single task. Therefore, one is also interested in the temporal evolution of brain activity to infer causal relations between activated brain regions. These causal relations may be described by a directed, task specific network which consists of activated brain regions as vertices and directed edges. The edges describe the causal relations. Inference of the task specific brain network from measurements like electroencephalography (EEG) or functional magnetic resonance imaging (fMRI) is challenging, due to the low spatial resolution of the former and the low temporal resolution of the latter. Here, we present a simulation study investigating a possible combined analysis of simultaneously measured EEG and fMRI data to address the challenge specified above. A nonlinear state space model is used to distinguish between the underlying brain states and the (simulated) EEG/fMRI measurements. We make use of a modified unscented Kalman filter and a corresponding unscented smoother for the estimation of the underlying neural activity. Model parameters are estimated using an expectation-maximization algorithm, which exploits the partial linearity of our model. Inference of the brain network structure is then achieved using directed partial correlation, a measure for Granger causality. The results indicate that the convolution effect of the fMRI forward model imposes a big challenge for the parameter estimation and reduces the influence of the fMRI in combined EEG–fMRI models. It remains to be investigated whether other models or similar combinations of other modalities such as, e.g., EEG and magnetoencephalography can increase the profit of the promising idea of combining various modalities

  13. Multi-Polarization ASAR Backscattering from Herbaceous Wetlands in Poyang Lake Region, China

    Huiyong Sang

    2014-05-01

    Full Text Available Wetlands are one of the most important ecosystems on Earth. There is an urgent need to quantify the biophysical parameters (e.g., plant height, aboveground biomass and map total remaining areas of wetlands in order to evaluate the ecological status of wetlands. In this study, Environmental Satellite/Advanced Synthetic Aperture Radar (ENVISAT/ASAR dual-polarization C-band data acquired in 2005 is tested to investigate radar backscattering mechanisms with the variation of hydrological conditions during the growing cycle of two types of herbaceous wetland species, which colonize lake borders with different elevation in Poyang Lake region, China. Phragmites communis (L. Trin. is semi-aquatic emergent vegetation with vertical stem and blade-like leaves, and the emergent Carex spp. has rhizome and long leaves. In this study, the potential of ASAR data in HH-, HV-, and VV-polarization in mapping different wetland types is examined, by observing their dynamic variations throughout the whole flooding cycle. The sensitivity of ASAR backscattering coefficients to vegetation parameters of plant height, fresh and dry biomass, and vegetation water content is also analyzed for Phragmites communis (L. Trin. and Carex spp. The research for Phragmites communis (L. Trin. shows that HH polarization is more sensitive to plant height and dry biomass than HV polarization. ASAR backscattering coefficients are relatively less sensitive to fresh biomass, especially in HV polarization. However, both are highly dependent on canopy water content. In contrast, the dependence of HH- and HV- backscattering from Carex community on vegetation parameters is poor, and the radar backscattering mechanism is controlled by ground water level.

  14. DEVELOPMENT OF ISLAMIC FINANCE MARKETS IN A MULTI-POLAR WORLD AND SUKUK ISSUANCE

    ÇANAKCI, Mehmet

    2014-01-01

    The financial crisis in the world economy after 2008 brought forward the importance of Islamic finance instruments and increased their usage in this way. Islamic finance, as a complementary component among financial instruments, provides sustainable material and spiritual welfare with its fairer, more participative and more sharing structure, by encouraging people/establishments that wishes to make investments and facilitate access to financing in economy. In this context “Sukuk” exports, whi...

  15. Effect of multipolar interaction on the effective thermal conductivity of nanofluids

    Zhou Xiao-Feng; Gao Lei

    2007-01-01

    Nanofluids or liquids with suspended nanoparticles are likely to be the future heat transfer media, as they exhibit higher thermal conductivity than those of liquids. It has been proposed that nanoparticles are apt to congregate and form clusters, and hence the interaction between nanoparticles becomes important. In this paper, by taking into account the interaction between nearest-neighbour inclusions, we adopt the multiple image method to investigate the effective thermal conductivity of nanofluids. Numerical results show that then the thermal conductivity ratio between the nanoparticles and fluids is large, and the two nanoparticles are close up and even touch, and the point-dipole theory such as Maxwell-Garnett theory becomes rough as many-body interactions are neglected. Our theoretical results on the effective thermal conductivity of CuO/water and Al2O3/water nanofluids are in good agreement with experimental data.

  16. Multipolarity of the 228.5-keV transition in 80Y

    We have unambiguously characterized the deexcitation of the 228.5-keV T1/2=4.7-s isomer in 80Y as an M3 transition. This result determines, in conjunction with other experimental data, the spin and parity of the 228.5-keV isomer and the 80Y ground state as 1- and 4-, respectively. (c) 2000 The American Physical Society

  17. Multipolar correlations and deformation effect on nuclear transition matrix elements of double-$\\beta $ decay

    Chandra, R; Rath, P K; Raina, P K; Hirsch, J G

    2009-01-01

    The two neutrino and neutrinoless double beta decay of $^{94,96}$Zr, $^{98,100}$Mo, $^{104}$Ru, $^{110}$Pd, $^{128,130}$Te and $^{150}$Nd isotopes for the $0^{+}\\to 0^{+}$ transition is studied within the PHFB framework along with an effective two-body interaction consisting of pairing, quadrupole-quadrupole and hexadecapole-hexadecapole correlations. It is found that the effect of hexadecapolar correlations can be assimilated substantially as a renormalization of the quadrupole-quadrupole interaction. The effect of deformation on nuclear transition matrix elements is investigated by varying the strength of quadrupolar correlations in the parent and daughter nuclei independently. The variation of the nuclear transition matrix elements as a function of the difference in deformation parameters of parent and daughter nuclei reveals that in general, the former tend to be maximum for equal deformation and they decrease as the difference in deformation parameters increases, exhibiting a very similar trend for the $...

  18. Resonant X-ray scattering and multipolar order in actinide dioxides

    Full text of publication follows: The discovery in 2002 of electric quadrupole ordering in the NpO2 opened a new chapter in the understanding of the low-temperature ground states of actinide dioxides, insulating compounds with the simple cubic CaF2 crystal structure and general formula U1-xNpxO2 (0 ≤ x ≤ 1). The phenomenon found at 25 K in NpO2 is that the 5f charge distribution develops an anisotropic component, with long-range ordering of the charge quadrupoles driven by a primary magnetic octupolar order parameter belonging to the totally symmetric irreducible representation of L = 3 in D3d symmetry (□1). The experiments consist of tuning the photon energy to the actinide M absorption edge (at which photon energy core 3d electrons are promoted to the partially occupied 5f valence states), and then, once the repeat of the anisotropic charge distribution is known, to measure the azimuthal distribution of the scattered resonant x-ray intensity. This intensity distribution is related to the symmetry of the 5f anisotropic charge distribution. The experiments were performed at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France, with the single crystals mounted in ITU. NpO2 shows no measurable magnetic dipole component. In 2003 experiments were performed on a single crystal with x = 0.25. Dipole ordering was found on both the U and Np ions, and quadrupolar ordering was also found associated with both ions. However, these were different from those in pure NpO2. Whereas a longitudinal (L) 3-k configuration was found for NpO2, the x = 0.25 sample was found to have a transverse (T) 3-k configuration. The understanding of these different configurations then allowed an experiment to be performed in 2005 on a single crystal of UO2. The azimuthal dependence of the intensity from non-specular reflections reveals 3-k T anti-ferro-electric-quadrupolar order also UO2. The complication in UO2 is that both dipole ordering and an internal distortion of the oxygen atoms due to the quadrupole ordering are present; these have contrived to make it difficult to observe directly the quadrupole ordering in UO2, although such ordering was predicted almost 40 years ago, and the oxygen displacements reported 30 years ago [5]. These experiments also suggest a qualitative explanation of the unusual behaviour of the mixed oxides with 0.40 < x < 0.80. In this region there is competition between the L and T quadrupole ordering, resulting in quadrupolar frustration and only short-range dipole and quadrupole ordering. (authors)

  19. NATO in a Multipolar World : U.S. Foreign Policy Discourse and the Future of NATO

    2012-01-01

    Oppgaven analyserer amerikansk utenrikspolitisks diskurs med tanke på utfordringer knyttet til NATO. Selv om NATO i utgangspunktet er ansett som en vellykket allianse har den, særlig siden slutten av den kalde krigen, vært et tema for flere debatter. Denne oppgaven tar for seg fire debatter som har vært sentrale rundt NATO og setter de i sammenheng med større spørsmål i amerikansk utenrikspolitikk. En av debattene er strukturelle og omhandler det transatlantiske forholdet, mens de andre er kn...

  20. Wnt Signaling Regulates Multipolar-to-Bipolar Transition of Migrating Neurons in the Cerebral Cortex

    Michael Boitard; Riccardo Bocchi; Kristof Egervari; Volodymyr Petrenko; Beatrice Viale; Stéphane Gremaud; Eloisa Zgraggen; Patrick Salmon; Jozsef Z. Kiss

    2015-01-01

    The precise timing of pyramidal cell migration from the ventricular germinal zone to the cortical plate is essential for establishing cortical layers, and migration errors can lead to neurodevelopmental disorders underlying psychiatric and neurological diseases. Here, we report that Wnt canonical as well as non-canonical signaling is active in pyramidal precursors during radial migration. We demonstrate using constitutive and conditional genetic strategies that transient downregulation of can...

  1. Binary black hole merger in the extreme-mass-ratio limit: a multipolar analysis

    Bernuzzi, Sebastiano

    2010-01-01

    Building up on previous work, we present a new calculation of the gravitational wave (GW) emission generated during the transition from quasi-circular inspiral to plunge, merger and ringdown by a binary system of nonspinning black holes, of masses $m_1$ and $m_2$, in the extreme mass ratio limit, $m_1 m_2\\ll(m_1+m_2)^2$. The relative dynamics of the system is computed {\\it without making any adiabatic approximation} by using an effective one body (EOB) description, namely by representing the binary by an effective particle of mass $\\mu=m_1 m_2/(m_1+m_2)$ moving in a (quasi-)Schwarzschild background of mass $M=m_1+m_2$ and submitted to an $\\O(\

  2. Multipolar representation of Maxwell and Schroedinger equations: Lagrangian and Hamiltonian formalisms: Examples

    Development of quantum engineering put forward new theoretical problems. Behaviour of a single mesoscopic cell (device) we may usually describe by equations of quantum mechanics. However, if experimentators gather hundreds of thousands of similar cells there arises some artificial medium that one already needs to describe by means of new electromagnetic equations. The same problem arises when we try to describe e.g. a sublattice structure of such complex substances like perovskites. It is demonstrated that the inherent primacy of vector potential in quantum systems leads to a generalization of the equations of electromagnetism by introducing in them toroid polarizations. To derive the equations of motion the Lagrangian and the Hamiltonian formalisms are used. Some examples where electromagnetic properties of molecules are described by the toroid moment are pointed out. (author). 26 refs, 7 figs

  3. Treatment of atrial fibrillation with radiofrequency ablation and simultaneous multipolar mapping of the pulmonary veins

    Rocha Neto Almino C.

    2001-01-01

    Full Text Available OBJECTIVE: To demonstrate the feasibility and safety of simultaneous catheterization and mapping of the 4 pulmonary veins for ablation of atrial fibrillation. METHODS: Ten patients, 8 with paroxysmal atrial fibrillation and 2 with persistent atrial fibrillation, refractory to at least 2 antiarrhythmic drugs and without structural cardiopathy, were consecutively studied. Through the transseptal insertion of 2 long sheaths, 4 pulmonary veins were simultaneously catheterized with octapolar microcatheters. After identification of arrhythmogenic foci radiofrequency was applied under angiographic or ultrasonographic control. RESULTS: During 17 procedures, 40 pulmonary veins were mapped, 16 of which had local ectopic activity, related or not with the triggering of atrial fibrillation paroxysms. At the end of each procedure, suppression of arrhythmias was obtained in 8 patients, and elimination of pulmonary vein potentials was accomplished in 4. During the clinical follow-up of 9.6±3 months, 7 patients remained in sinus rhythm, 5 of whom were using antiarrhythmic drugs that had previously been ineffective. None of the patients had pulmonary hypertension or evidence of stenosis in the pulmonary veins. CONCLUSION: Selective and simultaneous catheterization of the 4 pulmonary veins with microcatheters for simultaneous recording of their electrical activity is a feasible and safe procedure that may help ablation of atrial fibrillation.

  4. Dynamic polarizability and electric multipolar transitions in two electron atoms under exponential cosine screened coulomb potential

    Chaudhuri, Supriya K.; Modesto-Costa, Lucas; Mukherjee, Prasanta K.

    2016-05-01

    Detailed investigations on the frequency dependent polarizabilities, transition energies, oscillator strengths, and transition probabilities of two electron systems He, B e2 +, C4 + , and O6 + under electric dipolar (E1) and quadrupolar (E2) excitations have been performed using exponential cosine screened coulomb potential with a view to understand the structural behaviour of such systems due to external confinement produced by plasma environment. Time dependent coupled Hartree-Fock theory within a variational framework has been adopted for studying the first three low lying excited states 1 s2:1Se→1 s n p :1Po (n = 2, 3, 4) and 1 s n d :1De (n = 3, 4, 5) under such excitations. Quantitatively, the effect of confinement produced by the external plasma has been taken care of by considering the change in atomic potential through plasma screening, directly related to the coupling strength of the plasma with the atomic charge cloud. With increased plasma screening, a gradual destabilisation of the energy levels with subsequent reduction of the ionization potential and number of excited states has been observed. Behavioral pattern of the frequency dependent polarizabilities, excitation energies, oscillator strengths, and transition probabilities under systematic increase of the screening has been investigated. Results have been compared thoroughly with those available for free systems and under confinement by exponential cosine screened and screened Coulomb potential.

  5. Controlling multipolar surface plasmon excitation through the azimuthal phase structure of electron vortex beams

    Ugarte, Daniel; Ducati, Caterina

    2016-05-01

    We have theoretically studied how the azimuthal phase structure of an electron vortex beam excites surface plasmons on metal particles of different geometries as observed in electron energy loss spectroscopy (EELS). We have developed a semiclassical approximation combining a ring-shaped beam and the dielectric formalism. Our results indicate that for the case of total orbital angular momentum transfer, we can manipulate surface plasmon multipole excitation and even attain an enhancement factor of several orders of magnitude. Since electron vortex beams interact with particles mostly through effects due to azimuthal symmetry, i.e., in the plane perpendicular to the electron beam, anisotropy information (longitudinal and transversal) of the sample may be derived in EELS studies by comparing nonvortex and vortex beam measurements.

  6. Interpreting shadows: Arms control and defense planning in a rapidly changing multi-polar world

    King, D.R.

    1999-06-01

    The focus of arms control is changing. It now deals with issues affecting all nations and not just the super powers. A new framework for approaching non-proliferation of weapons of mass destruction and arms control could focus on a two-fold policy initiative. The first policy would be a new strategic `triad` built around conventional capability including rapidly deployable forces, regional ballistic missile defense, and long-range precision-strike capability. The second policy would employ an information strategy using the current diplomatic initiatives that appear to be the most productive, or unilateral and multilateral export controls, military assistance in the form of infrastructure, and confidence building measures. Continued success in arms control requires abandoning Cold War policies. Emerging policies will need to appreciate different world views. Good intelligence will be a key factor in the success of any policy orientation and its implementation. The focus needs to change from arms control involving the superpowers to arms control involving everyone.

  7. Multipolar universal relations between f-mode frequency and tidal deformability of compact stars

    Chan, T K; Leung, P T; Lin, L -M

    2014-01-01

    Though individual stellar parameters of compact stars usually demonstrate obvious dependence on the equation of state (EOS), EOS-insensitive universal formulas relating these parameters remarkably exist. In the present paper, we explore the inter-relationship between two such formulas, namely the f-I relation connecting the $f$-mode quadrupole oscillation frequency $\\omega_2$ and the moment of inertia $I$, and the I-Love-Q relations relating $I$, the quadrupole tidal deformability $\\lambda_2$, and the quadrupole moment $Q$, which have been proposed by Lau et al. [Astrophys. J. {\\bf 714}, 1234 (2010)], and Yagi and Yunes [Science, {\\bf 341}, 365 (2013)], respectively. A relativistic universal relation between $\\omega_l$ and $\\lambda_l$ with the same angular momentum $l=2,3,\\ldots$, the so called "diagonal f-Love relation" that holds for realistic compact stars and stiff polytropic stars, is unveiled here. An in-depth investigation in the Newtonian limit is further carried out to pinpoint its underlying physica...

  8. The impact of the new Earth gravity models on the measurement of the Lense-Thirring effect with a new satellite

    Iorio, L

    2005-01-01

    In this paper we investigate the opportunities offered by the new Earth gravity models from the dedicated CHAMP and, especially, GRACE missions to the project of measuring the general relativistic Lense-Thirring effect with a new Earth's artificial satellite. It turns out that it would be possible to abandon the stringent, and expensive, requirements on the orbital geometry of the originally prosed LARES mission (same semimajor axis a=12270 km of the existing LAGEOS and inclination i=70 deg) by inserting the new spacecraft in a relatively low, and cheaper, orbit (a=7500-8000 km, i\\sim 70 deg) and suitably combining its node Omega with those of LAGEOS and LAGEOS II in order to cancel out the first even zonal harmonic coefficients of the multipolar expansion of the terrestrial gravitational potential J_2, J_4 along with their temporal variations. The total systematic error due to the mismodelling in the remaining even zonal harmonics would amount to \\sim 1% and would be insensitive to departures of the inclinat...

  9. Human in vitro reporter model of neuronal development and early differentiation processes

    Bogdahn Ulrich

    2008-02-01

    Full Text Available Abstract Background During developmental and adult neurogenesis, doublecortin is an early neuronal marker expressed when neural stem cells assume a neuronal cell fate. To understand mechanisms involved in early processes of neuronal fate decision, we investigated cell lines for their capacity to induce expression of doublecortin upon neuronal differentiation and develop in vitro reporter models using doublecortin promoter sequences. Results Among various cell lines investigated, the human teratocarcinoma cell line NTERA-2 was found to fulfill our criteria. Following induction of differentiation using retinoic acid treatment, we observed a 16-fold increase in doublecortin mRNA expression, as well as strong induction of doublecortin polypeptide expression. The acquisition of a neuronal precursor phenotype was also substantiated by the establishment of a multipolar neuronal morphology and expression of additional neuronal markers, such as Map2, βIII-tubulin and neuron-specific enolase. Moreover, stable transfection in NTERA-2 cells of reporter constructs encoding fluorescent or luminescent genes under the control of the doublecortin promoter allowed us to directly detect induction of neuronal differentiation in cell culture, such as following retinoic acid treatment or mouse Ngn2 transient overexpression. Conclusion Induction of doublecortin expression in differentiating NTERA-2 cells suggests that these cells accurately recapitulate some of the very early events of neuronal determination. Hence, the use of reporter genes under the control of the doublecortin promoter in NTERA-2 cells will help us to investigate factors involved early in the course of neuronal differentiation processes. Moreover the ease to detect the induction of a neuronal program in this model will permit to perform high throughput screening for compounds acting on the early neuronal differentiation mechanisms.

  10. Distinguishing mechanisms of gamma frequency oscillations in human current source signals using a computational model of a laminar neocortical network

    Shane Lee

    2013-12-01

    Full Text Available Gamma frequency rhythms have been implicated in numerous studies for their role in healthy and abnormal brain function. The frequency band has been described to encompass as broad a range as 30–150 Hz. Crucial to understanding the role of gamma in brain function is an identification of the underlying neural mechanisms, which is particularly difficult in the absence of invasive recordings in macroscopic human signals such as those from magnetoencephalography (MEG and electroencephalography (EEG. Here, we studied features of current dipole (CD signals from two distinct mechanisms of gamma generation, using a computational model of a laminar cortical circuit designed specifically to simulate CDs in a biophysically principled manner (Jones et al., 2007; Jones et al., 2009. We simulated spiking pyramidal interneuronal gamma (PING whose period is regulated by the decay time constant of GABAA-mediated synaptic inhibition and also subthreshold gamma driven by gamma-periodic exogenous excitatory synaptic drive. Our model predicts distinguishable CD features created by spiking PING compared to subthreshold driven gamma that can help to disambiguate mechanisms of gamma oscillations in human signals. We found that gamma rhythms in neocortical layer 5 can obscure a simultaneous, independent gamma in layer 2/3. Further, we arrived at a novel interpretation of the origin of high gamma frequency rhythms (100–150 Hz, showing that they emerged from a specific temporal feature of CDs associated with single cycles of PING activity and did not reflect a separate rhythmic process. Last we show that the emergence of observable subthreshold gamma required highly coherent exogenous drive. Our results are the first to demonstrate features of gamma oscillations in human current source signals that distinguish cellular and circuit level mechanisms of these rhythms and may help guide understanding of their functional role.

  11. How neurons migrate: a dynamic in-silico model of neuronal migration in the developing cortex

    Setty, Yaki

    2011-09-30

    Abstract Background Neuronal migration, the process by which neurons migrate from their place of origin to their final position in the brain, is a central process for normal brain development and function. Advances in experimental techniques have revealed much about many of the molecular components involved in this process. Notwithstanding these advances, how the molecular machinery works together to govern the migration process has yet to be fully understood. Here we present a computational model of neuronal migration, in which four key molecular entities, Lis1, DCX, Reelin and GABA, form a molecular program that mediates the migration process. Results The model simulated the dynamic migration process, consistent with in-vivo observations of morphological, cellular and population-level phenomena. Specifically, the model reproduced migration phases, cellular dynamics and population distributions that concur with experimental observations in normal neuronal development. We tested the model under reduced activity of Lis1 and DCX and found an aberrant development similar to observations in Lis1 and DCX silencing expression experiments. Analysis of the model gave rise to unforeseen insights that could guide future experimental study. Specifically: (1) the model revealed the possibility that under conditions of Lis1 reduced expression, neurons experience an oscillatory neuron-glial association prior to the multipolar stage; and (2) we hypothesized that observed morphology variations in rats and mice may be explained by a single difference in the way that Lis1 and DCX stimulate bipolar motility. From this we make the following predictions: (1) under reduced Lis1 and enhanced DCX expression, we predict a reduced bipolar migration in rats, and (2) under enhanced DCX expression in mice we predict a normal or a higher bipolar migration. Conclusions We present here a system-wide computational model of neuronal migration that integrates theory and data within a precise

  12. Use of the isolated problem approach for multi-compartment BEM models of electro-magnetic source imaging

    Gençer, Nevzat G.; Akalin-Acar, Zeynep

    2005-07-01

    The isolated problem approach (IPA) is a method used in the boundary element method (BEM) to overcome numerical inaccuracies caused by the high-conductivity difference in the skull and the brain tissues in the head. Hämäläinen and Sarvas (1989 IEEE Trans. Biomed. Eng. 36 165-71) described how the source terms can be updated to overcome these inaccuracies for a three-layer head model. Meijs et al (1989 IEEE Trans. Biomed. Eng. 36 1038-49) derived the integral equations for the general case where there are an arbitrary number of layers inside the skull. However, the IPA is used in the literature only for three-layer head models. Studies that use complex boundary element head models that investigate the inhomogeneities in the brain or model the cerebrospinal fluid (CSF) do not make use of the IPA. In this study, the generalized formulation of the IPA for multi-layer models is presented in terms of integral equations. The discretized version of these equations are presented in two different forms. In a previous study (Akalinodotn-Acar and Gençer 2004 Phys. Med. Biol. 49 5011-28), we derived formulations to calculate the electroencephalography and magnetoencephalography transfer matrices assuming a single layer in the skull. In this study, the transfer matrix formulations are updated to incorporate the generalized IPA. The effects of the IPA are investigated on the accuracy of spherical and realistic models when the CSF layer and a tumour tissue are included in the model. It is observed that, in the spherical model, for a radial dipole 1 mm close to the brain surface, the relative difference measure (RDM*) drops from 1.88 to 0.03 when IPA is used. For the realistic model, the inclusion of the CSF layer does not change the field pattern significantly. However, the inclusion of an inhomogeneity changes the field pattern by 25% for a dipole oriented towards the inhomogeneity. The effect of the IPA is also investigated when there is an inhomogeneity in the brain. In

  13. Modeling Model Slicers

    Blouin A.; Combemale B.; Baudry B.; Beaudoux O.

    2011-01-01

    International audience Among model comprehension tools, model slicers are tools that extract a subset from a model, for a specific purpose. Model slicers are tools that let modelers rapidly gather relevant knowledge from large models. However, existing slicers are dedicated to one modeling language. This is an issue when we observe that new domain specific modeling languages (DSMLs), for which we want slicing abilities, are created almost on a daily basis. This paper proposes the Kompren l...

  14. Testing the geomagnetic dipole and reversing dynamo models over Earth's cooling history

    Heimpel, Moritz; Evans, Ted

    2014-05-01

    Continental drift reconstructions rely on the assumption that Earth's mean magnetic field has been a geocentric axial dipole over geologic time. However, the coupled dynamics of mantle and core convection may have had profound effects on the magnetic field in the distant past. Previous dynamo models have linked differences between polar and equatorial mantle heat flow to apparently anomalous paleomagnetic fields, and changes in reversal frequency. Here we use the inclination test (Evans, 1976) to interpret observational magnetic field models and polarity-reversing numerical dynamos representing various convective states of the mantle and core. Dynamo models with uniform buoyancy flux represent three convective states of the mantle and core: (1) present era Earth, driven thermo-chemically at the inner core boundary; (2) mantle overturn, with elevated heat flux at the core-mantle boundary, and (3) ancient Earth prior to inner core nucleation, with buoyancy production solely at the CMB. Consistent with Earth's present magnetic field, dynamos driven by buoyancy due to inner core growth are nearly dipolar. In contrast, elevated CMB heat flow yields small to moderate inclination flattening due to a persistent octupole that reverses synchronously with the dipole. For the ancient Earth models the relatively strong octupole component tends to stabilize the dynamo and decrease the reversal frequency. Our results, along with evidence of a young inner core, imply that an entirely liquid core contributed to shallow inclinations in Precambrian time. We also run models with latitudinally variable heat flux boundary conditions to further investigate the relationship between dynamo flow fields, the octupole component, magnetic inclinations and reversal frequency. For models with increased polar CMB heat flux we find that the relative strength of the octupole component increases in proportion to latitudinal heat flux variation. On the other hand, models are very sensitive to

  15. Modeling Model Uncertainty

    Onatski, Alexei; Williams, Noah

    2003-01-01

    Recently there has been much interest in studying monetary policy under model uncertainty. We develop methods to analyze different sources of uncertainty in one coherent structure useful for policy decisions. We show how to estimate the size of the uncertainty based on time series data, and incorporate this uncertainty in policy optimization. We propose two different approaches to modeling model uncertainty. The first is model error modeling, which imposes additional structure on the errors o...

  16. A Real-Time Magnetoencephalography Brain-Computer Interface Using Interactive 3D Visualization and the Hadoop Ecosystem

    Wilbert A. McClay

    2015-09-01

    Full Text Available Ecumenically, the fastest growing segment of Big Data is human biology-related data and the annual data creation is on the order of zetabytes. The implications are global across industries, of which the treatment of brain related illnesses and trauma could see the most significant and immediate effects. The next generation of health care IT and sensory devices are acquiring and storing massive amounts of patient related data. An innovative Brain-Computer Interface (BCI for interactive 3D visualization is presented utilizing the Hadoop Ecosystem for data analysis and storage. The BCI is an implementation of Bayesian factor analysis algorithms that can distinguish distinct thought actions using magneto encephalographic (MEG brain signals. We have collected data on five subjects yielding 90% positive performance in MEG mid- and post-movement activity. We describe a driver that substitutes the actions of the BCI as mouse button presses for real-time use in visual simulations. This process has been added into a flight visualization demonstration. By thinking left or right, the user experiences the aircraft turning in the chosen direction. The driver components of the BCI can be compiled into any software and substitute a user’s intent for specific keyboard strikes or mouse button presses. The BCI’s data analytics OPEN ACCESS Brain. Sci. 2015, 5 420 of a subject’s MEG brainwaves and flight visualization performance are stored and analyzed using the Hadoop Ecosystem as a quick retrieval data warehouse.

  17. A Real-Time Magnetoencephalography Brain-Computer Interface Using Interactive 3D Visualization and the Hadoop Ecosystem.

    McClay, Wilbert A; Yadav, Nancy; Ozbek, Yusuf; Haas, Andy; Attias, Hagaii T; Nagarajan, Srikantan S

    2015-01-01

    Ecumenically, the fastest growing segment of Big Data is human biology-related data and the annual data creation is on the order of zetabytes. The implications are global across industries, of which the treatment of brain related illnesses and trauma could see the most significant and immediate effects. The next generation of health care IT and sensory devices are acquiring and storing massive amounts of patient related data. An innovative Brain-Computer Interface (BCI) for interactive 3D visualization is presented utilizing the Hadoop Ecosystem for data analysis and storage. The BCI is an implementation of Bayesian factor analysis algorithms that can distinguish distinct thought actions using magneto encephalographic (MEG) brain signals. We have collected data on five subjects yielding 90% positive performance in MEG mid- and post-movement activity. We describe a driver that substitutes the actions of the BCI as mouse button presses for real-time use in visual simulations. This process has been added into a flight visualization demonstration. By thinking left or right, the user experiences the aircraft turning in the chosen direction. The driver components of the BCI can be compiled into any software and substitute a user's intent for specific keyboard strikes or mouse button presses. The BCI's data analytics OPEN ACCESS Brain. Sci. 2015, 5 420 of a subject's MEG brainwaves and flight visualization performance are stored and analyzed using the Hadoop Ecosystem as a quick retrieval data warehouse. PMID:26437432

  18. Reconstructing coherent networks from electroencephalography and magnetoencephalography with reduced contamination from volume conduction or magnetic field spread.

    Mark Drakesmith

    Full Text Available Volume conduction (VC and magnetic field spread (MFS induce spurious correlations between EEG/MEG sensors, such that the estimation of functional networks from scalp recordings is inaccurate. Imaginary coherency [1] reduces VC/MFS artefacts between sensors by assuming that instantaneous interactions are caused predominantly by VC/MFS and do not contribute to the imaginary part of the cross-spectral densities (CSDs. We propose an adaptation of the dynamic imaging of coherent sources (DICS [2] - a method for reconstructing the CSDs between sources, and subsequently inferring functional connectivity based on coherences between those sources. Firstly, we reformulate the principle of imaginary coherency by performing an eigenvector decomposition of the imaginary part of the CSD to estimate the power that only contributes to the non-zero phase-lagged (NZPL interactions. Secondly, we construct an NZPL-optimised spatial filter with two a priori assumptions: (1 that only NZPL interactions exist at the source level and (2 the NZPL CSD at the sensor level is a good approximation of the projected source NZPL CSDs. We compare the performance of the NZPL method to the standard method by reconstructing a coherent network from simulated EEG/MEG recordings. We demonstrate that, as long as there are phase differences between the sources, the NZPL method reliably detects the underlying networks from EEG and MEG. We show that the method is also robust to very small phase lags, noise from phase jitter, and is less sensitive to regularisation parameters. The method is applied to a human dataset to infer parts of a coherent network underpinning face recognition.

  19. A Real-Time Magnetoencephalography Brain-Computer Interface Using Interactive 3D Visualization and the Hadoop Ecosystem

    McClay, Wilbert A.; Yadav, Nancy; Ozbek, Yusuf; Haas, Andy; Attias, Hagaii T.; Nagarajan, Srikantan S.

    2015-01-01

    Ecumenically, the fastest growing segment of Big Data is human biology-related data and the annual data creation is on the order of zetabytes. The implications are global across industries, of which the treatment of brain related illnesses and trauma could see the most significant and immediate effects. The next generation of health care IT and sensory devices are acquiring and storing massive amounts of patient related data. An innovative Brain-Computer Interface (BCI) for interactive 3D visualization is presented utilizing the Hadoop Ecosystem for data analysis and storage. The BCI is an implementation of Bayesian factor analysis algorithms that can distinguish distinct thought actions using magneto encephalographic (MEG) brain signals. We have collected data on five subjects yielding 90% positive performance in MEG mid- and post-movement activity. We describe a driver that substitutes the actions of the BCI as mouse button presses for real-time use in visual simulations. This process has been added into a flight visualization demonstration. By thinking left or right, the user experiences the aircraft turning in the chosen direction. The driver components of the BCI can be compiled into any software and substitute a user’s intent for specific keyboard strikes or mouse button presses. The BCI’s data analytics of a subject’s MEG brainwaves and flight visualization performance are stored and analyzed using the Hadoop Ecosystem as a quick retrieval data warehouse. PMID:26437432

  20. Non-invasive long-term recordings of cortical 'direct current' (DC-) activity in humans using magnetoencephalography.

    Mackert, B M; Wübbeler, G; Burghoff, M; Marx, P; Trahms, L; Curio, G

    1999-10-01

    Recently, biomagnetic fields below 0.1 Hz arising from nerve or muscle injury currents have been measured non-invasively using superconducting quantum interference devices (SQUIDs). Here we report first long-term recordings of cortical direct current (DC) fields in humans based on a horizontal modulation (0.4 Hz) of the body and, respectively, head position beneath the sensor array: near-DC fields with amplitudes between 90 and 540 fT were detected in 5/5 subjects over the auditory cortex throughout prolonged stimulation periods (here: 30 s) during which subjects were listening to concert music. These results prove the feasibility to record non-invasively low amplitude near-DC magnetic fields of the human brain and open the perspective for studies on DC-phenomena in stroke, such as anoxic depolarization or periinfarct depolarization, and in migraine patients. PMID:10515183

  1. A marker for differentiation of capabilities for processing of musical harmonies as detected by magnetoencephalography in musicians.

    Beisteiner, R; Erdler, M; Mayer, D; Gartus, A; Edward, V; Kaindl, T; Golaszewski, S; Lindinger, G; Deecke, L

    1999-12-17

    This investigation was designed to study the characteristics of a marker for harmonic processing and to test whether it could be used for differentiating harmonic processing capabilities. The first three chords of an ordinary musical cadenca were presented to the left ear to establish a harmonic context followed by a harmonic or non-harmonic target tone. Cadencas were presented rapidly and randomly in different keys to render the task difficult. Results showed a specific P3m (magnetic P300) effect to the non-harmonic targets which was only visible in subjects with low target recognition errors. Low resolution electro-magnetic tomography current density maps showed P3m sources in the right temporoparietal, left temporoparietal and frontocentral brain areas with right temporoparietal sources being strongest and most reliable. The results offer new possibilities to selectively study harmonic variables in music processing. PMID:10643892

  2. Business Models as Models

    Baden-Fuller, C.; Morgan, M S

    2010-01-01

    Drawing on research undertaken in the history and philosophy of science, with particular reference to the extensive literature which discusses the use of models in biology and economics, we explore the question ‘Are Business Models useful?’ We point out that they act as various forms of model: to provide means to describe and classify businesses; to operate as sites for scientific investigation; and to act as recipes for creative managers. We argue that studying business models as models is r...

  3. Nonlinear interactions in the thalamocortical loop in essential tremor: A model-based frequency domain analysis.

    He, F; Sarrigiannis, P G; Billings, S A; Wei, H; Rowe, J; Romanowski, C; Hoggard, N; Hadjivassilliou, M; Rao, D G; Grünewald, R; Khan, A; Yianni, J

    2016-06-01

    There is increasing evidence to suggest that essential tremor has a central origin. Different structures appear to be part of the central tremorogenic network, including the motor cortex, the thalamus and the cerebellum. Some studies using electroencephalogram (EEG) and magnetoencephalography (MEG) show linear association in the tremor frequency between the motor cortex and the contralateral tremor electromyography (EMG). Additionally, high thalamomuscular coherence is found with the use of thalamic local field potential (LFP) recordings and tremulous EMG in patients undergoing surgery for deep brain stimulation (DBS). Despite a well-established reciprocal anatomical connection between the thalamus and cortex, the functional association between the two structures during "tremor-on" periods remains elusive. Thalamic (Vim) LFPs, ipsilateral scalp EEG from the sensorimotor cortex and contralateral tremor arm EMG recordings were obtained from two patients with essential tremor who had undergone successful surgery for DBS. Coherence analysis shows a strong linear association between thalamic LFPs and contralateral tremor EMG, but the relationship between the EEG and the thalamus is much less clear. These measurements were then analyzed by constructing a novel parametric nonlinear autoregressive with exogenous input (NARX) model. This new approach uncovered two distinct and not overlapping frequency "channels" of communication between Vim thalamus and the ipsilateral motor cortex, defining robustly "tremor-on" versus "tremor-off" states. The associated estimated nonlinear time lags also showed non-overlapping values between the two states, with longer corticothalamic lags (exceeding 50ms) in the tremor active state, suggesting involvement of an indirect multisynaptic loop. The results reveal the importance of the nonlinear interactions between cortical and subcortical areas in the central motor network of essential tremor. This work is important because it demonstrates

  4. Model Validation and Model Error Modeling

    Ljung, Lennart

    1999-01-01

    To validate an estimated model and to have a good understanding of its reliability is a central aspect of System Identification. This contribution discusses these aspects in the light of model error models that are explicit descriptions of the model error. A model error model is implicitly present in most model validation methods, so the concept is more of a representation form than a set of new techniques. Traditional model validation is essentially a test of whether the confidence region of...

  5. On macromolecular refinement at subatomic resolution withinteratomic scatterers

    Afonine, Pavel V.; Grosse-Kunstleve, Ralf W.; Adams, Paul D.; Lunin, Vladimir Y.; Urzhumtsev, Alexandre

    2007-11-09

    A study of the accurate electron density distribution in molecular crystals at subatomic resolution, better than {approx} 1.0 {angstrom}, requires more detailed models than those based on independent spherical atoms. A tool conventionally used in small-molecule crystallography is the multipolar model. Even at upper resolution limits of 0.8-1.0 {angstrom}, the number of experimental data is insufficient for the full multipolar model refinement. As an alternative, a simpler model composed of conventional independent spherical atoms augmented by additional scatterers to model bonding effects has been proposed. Refinement of these mixed models for several benchmark datasets gave results comparable in quality with results of multipolar refinement and superior of those for conventional models. Applications to several datasets of both small- and macro-molecules are shown. These refinements were performed using the general-purpose macromolecular refinement module phenix.refine of the PHENIX package.

  6. Harnessing Fluorine-Sulfur Contacts and Multipolar Interactions for the Design of p53 Mutant Y220C Rescue Drugs.

    Bauer, Matthias R; Jones, Rhiannon N; Baud, Matthias G J; Wilcken, Rainer; Boeckler, Frank M; Fersht, Alan R; Joerger, Andreas C; Spencer, John

    2016-08-19

    Many oncogenic mutants of the tumor suppressor p53 are conformationally unstable, including the frequently occurring Y220C mutant. We have previously developed several small-molecule stabilizers of this mutant. One of these molecules, PhiKan083, 1-(9-ethyl-9H-carbazole-3-yl)-N-methylmethanamine, binds to a mutation-induced surface crevice with a KD = 150 μM, thereby increasing the melting temperature of the protein and slowing its rate of aggregation. Incorporation of fluorine atoms into small molecule ligands can substantially improve binding affinity to their protein targets. We have, therefore, harnessed fluorine-protein interactions to improve the affinity of this ligand. Step-wise introduction of fluorines at the carbazole ethyl anchor, which is deeply buried within the binding site in the Y220C-PhiKan083 complex, led to a 5-fold increase in affinity for a 2,2,2-trifluoroethyl anchor (ligand efficiency of 0.3 kcal mol(-1) atom(-1)). High-resolution crystal structures of the Y220C-ligand complexes combined with quantum chemical calculations revealed favorable interactions of the fluorines with protein backbone carbonyl groups (Leu145 and Trp146) and the sulfur of Cys220 at the mutation site. Affinity gains were, however, only achieved upon trifluorination, despite favorable interactions of the mono- and difluorinated anchors with the binding pocket, indicating a trade-off between energetically favorable protein-fluorine interactions and increased desolvation penalties. Taken together, the optimized carbazole scaffold provides a promising starting point for the development of high-affinity ligands to reactivate the tumor suppressor function of the p53 mutant Y220C in cancer cells. PMID:27267810

  7. Correction of Multipolar Field Errors in Insertion Regions for the Phase 1 LHC Upgrade and Dynamic Aperture

    Tomás, R; de Maria, R

    2008-01-01

    The Phase 1 upgrade of the LHC interaction regions aims at increasing the machine luminosity by reducing the beam size at the interaction point. This requires an in-depth review of the full insertion region layout and a large set of options have been proposed with conceptually different designs. This paper reports on a general approach for the compensation of the non-linear eld errors of the insertion region magnets by means of dedicated correctors. The goal is to use the same correction approach for all the different layouts. The correction algorithm is based on the computation of the high orders of the polynomial transfer map using MAD-X and Polymorphic Tracking Code, while the actual performance of the method is estimated by computing the dynamic aperture of the layouts under study.

  8. Disarmament and security in a multipolar world: Non-proliferation, regional cooperation, keeping and building the peace

    In the context of disarmament process entering a new phase issues of consolidating the non-proliferation regime nuclear-weapon-free zones, export control regime of nuclear materials, and future of nuclear weapons are discussed. 8 notes

  9. Maternal inheritance of mitochondria: multipolarity, multiallelism and hierarchical transmission of mitochondrial DNA in the true slime mold Physarum polycephalum.

    Moriyama, Yohsuke; Kawano, Shigeyuki

    2010-03-01

    Direct evidence of digestion of paternal mitochondrial DNA (mtDNA) has been found in the true slime mold Physarum polycephalum. This is the first report on the selective digestion of mtDNA inside the zygote, and is striking evidence for the mechanism of maternal inheritance of mitochondria. Moreover, two mitochondrial nuclease activities were detected in this organism as-candidates for the nucleases responsible for selective digestion of mtDNA. In the true slime mold, there is an additional-feature of the uniparental inheritance of mitochondria.Although mitochondria are believed to be inherited from the maternal lineage in nearly all eukaryotes, the mating types of the true slime mold P. polycephalum is not restricted to two: there are three mating loci--matA, matB,and matC--and these loci have 16, 15, and 3 alleles,-respectively. Interestingly, the transmission patterns of mtDNA are determined by the matA locus, in a hierarchical-fashion (matA hierarchy) as follows: matA7[matA2[matA11[matA12[matA15/matA16[matA1[matA6.The strain possessing the higher status of matA would be the mtDNA donor in crosses. Furthermore, we have found that some crosses showed biparental inheritance of mitochondria.This review describes the phenomenon of hierarchical transmission of mtDNA in true slime molds, and discusses the presumed molecular mechanism of maternal and biparental inheritance. PMID:20082112

  10. Preferred Ice Crystal Orientation Fabric Measurements within the Greenland Ice Sheet Using Multi-Polarization Radar Data

    Velez-Gonzalez, J. A.; JiLu, L.; Leuschen, C.; Gogineni, P.; Van der Veen, C. J.; Tsoflias, G. P.; Drews, R.; Harish, A. R.

    2013-12-01

    Discharge of ice from the Greenland Ice Sheet to the ocean has increased significantly over the last 25 years due to the acceleration of important outlet glaciers. It was reported that the Greenland Ice Sheet contributed about 2.5 m out of about 6 m of sea-level rise during the Eemian interglacial period. The temperatures during Eemian were reported to be about 8o×4o C higher than the mean of the past millennium. Laboratory measurements have shown that glacial ice, characterized by preferred crystal orientation fabric (COF), is three times more deformable than ice with randomly oriented crystalline structures. Layers characterized by preferred ice COF can influence the flow behavior of a glacier or ice sheet. However, COF measurements are typically obtained from ice cores, and thus are very spatially limited and mostly constrained to areas with little ice flow. A more efficient technique to map the extent of ice fabric over larger regions of ice sheets is needed to better understand the effects on large scale ice flow processes. Radar measurements are capable of discriminating between reflections caused by changes in density, electrical permittivity and COF by exploiting the anisotropic and birefringent properties of ice crystals. For this investigation two radar datasets were collected during the survey of the Greenland Eemian Ice Drilling Site (77.45°N 51.06°W) in August 2008, using a ground-based and chirped-pulse Multi-Channel Radar Depth Sounder (MCRDS) developed by the Center for Remote Sensing of Ice Sheets (CReSIS). The radar used two transmit and eight receive antennas at the center frequency of 150 MHz with a bandwidth of 30 MHz. The first data set consisted of polarimatric measurements acquired in a circular pattern (radius: 35 m) with two co-polarized antenna orientations (one transmitter and four receivers oriented with 90° offsets in the directions of the incident H-Field and E-Field, respectively). Analysis of the circular data shows a periodic power variation with four distinct extinction patterns occurring at 90 degree intervals starting at approximately 700 m depth. Furthermore a 20 degree phase change is observed between the E- and H-field data. Both observations suggest that approximately 72% of the 2542m ice column exhibits birefringent anisotropy caused by preferred ice crystal orientation. The second dataset was acquired in a grid pattern consisting of twenty 10-Km 2D lines (NW to SE) spaced at 0.5-Km and three 10-Km lines (NE to SW) spaced at 2.5-Km. Both transmit and eight receive antenna were oriented parallel to the vehicle track, resulting in E-Field co-polarized data. We will determine the dominant COF relative to the ice divide for a 100 square Km region around the NEEM camp using the results from both datasets. The results of this investigation will be compared to the NEEM ice core observations to determine the accuracy of the analysis. In this investigation we will provide a brief overview of the system and experiments and present the results of data analysis.

  11. Actant Models

    Poulsen, Helle

    1996-01-01

    This paper presents a functional modelling method called Actant Modelling rooted in linguistics and semiotics. Actant modelling can be integrated with Multilevel Flow Modelling (MFM) in order to give an interpretation of actants.......This paper presents a functional modelling method called Actant Modelling rooted in linguistics and semiotics. Actant modelling can be integrated with Multilevel Flow Modelling (MFM) in order to give an interpretation of actants....

  12. Modelling the models

    Anaïs Schaeffer

    2012-01-01

    By analysing the production of mesons in the forward region of LHC proton-proton collisions, the LHCf collaboration has provided key information needed to calibrate extremely high-energy cosmic ray models.   Average transverse momentum (pT) as a function of rapidity loss ∆y. Black dots represent LHCf data and the red diamonds represent SPS experiment UA7 results. The predictions of hadronic interaction models are shown by open boxes (sibyll 2.1), open circles (qgsjet II-03) and open triangles (epos 1.99). Among these models, epos 1.99 shows the best overall agreement with the LHCf data. LHCf is dedicated to the measurement of neutral particles emitted at extremely small angles in the very forward region of LHC collisions. Two imaging calorimeters – Arm1 and Arm2 – take data 140 m either side of the ATLAS interaction point. “The physics goal of this type of analysis is to provide data for calibrating the hadron interaction models – the well-known &...

  13. Modelling Practice

    Cameron, Ian; Gani, Rafiqul

    2011-01-01

    This chapter deals with the practicalities of building, testing, deploying and maintaining models. It gives specific advice for each phase of the modelling cycle. To do this, a modelling framework is introduced which covers: problem and model definition; model conceptualization; model data...... requirements; model construction; model solution; model verification; model validation and finally model deployment and maintenance. Within the adopted methodology, each step is discussedthrough the consideration of key issues and questions relevant to the modelling activity. Practical advice, based on many...... years of experience is providing in directing the reader in their activities.Traps and pitfalls are discussed and strategies also given to improve model development towards “fit-for-purpose” models. The emphasis in this chapter is the adoption and exercise of a modelling methodology that has proven very...

  14. Model misinterpretation

    Daniel J Kliebenstein

    2012-01-01

    Models of myriad forms are rapidly becoming central to biology. This ranges from statistical models that are fundamental to the interpretation of experimental results to ODE models that attempt to describe the results in a mechanistic format. Models will be more and more essential to biologists but this growing importance requires all model users to become more sophisticated about what is in a model and how that limits the usability of the model. This review attempts to relay the potential pi...

  15. Promoting Models

    Li, Qin; Zhao, Yongxin; Wu, Xiaofeng; Liu, Si

    There can be multitudinous models specifying aspects of the same system. Each model has a bias towards one aspect. These models often override in specific aspects though they have different expressions. A specification written in one model can be refined by introducing additional information from other models. The paper proposes a concept of promoting models which is a methodology to obtain refinements with support from cooperating models. It refines a primary model by integrating the information from a secondary model. The promotion principle is not merely an academic point, but also a reliable and robust engineering technique which can be used to develop software and hardware systems. It can also check the consistency between two specifications from different models. A case of modeling a simple online shopping system with the cooperation of the guarded design model and CSP model illustrates the practicability of the promotion principle.

  16. Models within models

    Anyone who worries that physicists are running out of interesting challenges to tackle and important problems to solve should read the two, very different feature articles in this issue. In 'Climate change: complexity in action', Klaus Hasselmann and colleagues write about the challenges of including economic and political dimensions in computer simulations of climate change. It is hard to imagine a physics-based topic that has a greater impact on the world at large. In 'Quarks, diquarks and pentaquarks', Robert Jaffe and Frank Wilczek describe our current understanding of quantum chromodynamics and the strong nuclear force. In this case it is hard to think of many more difficult problems in fundamental physics. Traditional climate modelling is difficult enough because a whole range of effects in the atmosphere and the oceans have to be taken into account. It typically takes weeks for a state-of-the-art supercomputer to simulate 100 years of climate change with a horizontal resolution of 100 km. But climate change is about much more than solving difficult differential equations - there are crucial social, political and economic influences as well. Some researchers, including a significant number of physicists, have started to look at this integrated-assessment approach. The first challenge is to develop climate models that take minutes to run on a laptop. The next challenge is to develop analogous models that work in the social, political and economic arenas - which is not a trivial task - and then integrate all these different models and explore all the possible global-warming scenarios. Physicists also hope to integrate quantum chromodynamics (QCD) into the larger framework of a so-called theory of everything. Like climate modellers, particle theorists working on QCD require enormous computational resources for their calculations, and even then there are limits to what can be achieved (e.g. the mass of the proton has yet to be calculated from first principles

  17. Model Warehouse

    2003-01-01

    This paper puts forward a new conception:model warehouse,analyzes the reason why model warehouse appears and introduces the characteristics and architecture of model warehouse.Last,this paper points out that model warehouse is an important part of WebGIS.

  18. Constitutive Models

    Sales-Cruz, Mauricio; Piccolo, Chiara; Heitzig, Martina;

    2011-01-01

    This chapter presents various types of constitutive models and their applications. There are 3 aspects dealt with in this chapter, namely: creation and solution of property models, the application of parameter estimation and finally application examples of constitutive models. A systematic...... procedure is introduced for the analysis and solution of property models. Models that capture and represent the temperature dependent behaviour of physical properties are introduced, as well as equation of state models (EOS) such as the SRK EOS. Modelling of liquid phase activity coefficients are also...... covered, illustrating several models such as the Wilson equation and NRTL equation, along with their solution strategies. A section shows how to use experimental data to regress the property model parameters using a least squares approach. A full model analysis is applied in each example that discusses...

  19. Model error

    Katerina Simons

    1997-01-01

    Modern finance would not have been possible without models. Increasingly complex quantitative models drive financial innovation and the growth of derivatives markets. Models are necessary to value financial instruments and to measure the risks of individual positions and portfolios. Yet when used inappropriately, the models themselves can become an important source of risk. Recently, several well-publicized instances occurred of institutions suffering significant losses attributed to model er...

  20. Model cities

    M Batty

    2007-01-01

    The term ?model? is now central to our thinking about how weunderstand and design cities. We suggest a variety of ways inwhich we use ?models?, linking these ideas to Abercrombie?sexposition of Town and Country Planning which represented thestate of the art fifty years ago. Here we focus on using models asphysical representations of the city, tracing the development ofsymbolic models where the focus is on simulating how functiongenerates form, to iconic models where the focus is on representi...

  1. Supermatrix models

    Yost, S.A.

    1991-05-01

    Radom matrix models based on an integral over supermatrices are proposed as a natural extension of bosonic matrix models. The subtle nature of superspace integration allows these models to have very different properties from the analogous bosonic models. Two choices of integration slice are investigated. One leads to a perturbative structure which is reminiscent of, and perhaps identical to, the usual Hermitian matrix models. Another leads to an eigenvalue reduction which can be described by a two component plasma in one dimension. A stationary point of the model is described.

  2. Modelling Overview

    Larsen, Lars Bjørn; Vesterager, Johan

    This report provides an overview of the existing models of global manufacturing, describes the required modelling views and associated methods and identifies tools, which can provide support for this modelling activity.The model adopted for global manufacturing is that of an extended enterprise....... One or more units from beyond the network may complement the extended enterprise. The common reference model for this extended enterprise will utilise GERAM (Generalised Enterprise Reference Architecture and Methodology) to provide an architectural framework for the modelling carried out within the...

  3. Geochemical modeling

    Contributions to the workshop 'Geochemical modeling' from 19 to 20 September 1990 at the Karlsruhe Nuclear Research Centre. The report contains the programme and a selection of the lectures held at the workshop 'Geochemical modeling'. (BBR)

  4. ENTRAINMENT MODELS

    This presentation presented information on entrainment models. Entrainment models use entrainment hypotheses to express the continuity equation. The advantage is that plume boundaries are known. A major disadvantage is that the problems that can be solved are rather simple. The ...

  5. Enterprise Modeling

    Fox, Mark S.; Gruninger, Michael

    1998-01-01

    To remain competitive, enterprises must become increasingly agile and integrated across their functions. Enterprise models play a critical role in this integration, enabling better designs for enterprises, analysis of their performance, and management of their operations. This article motivates the need for enterprise models and introduces the concepts of generic and deductive enterprise models. It reviews research to date on enterprise modeling and considers in detail the Toronto virtual ent...

  6. Battery Modeling

    Jongerden, M.R.; Haverkort, B.R.

    2008-01-01

    The use of mobile devices is often limited by the capacity of the employed batteries. The battery lifetime determines how long one can use a device. Battery modeling can help to predict, and possibly extend this lifetime. Many different battery models have been developed over the years. However, with these models one can only compute lifetimes for specific discharge profiles, and not for workloads in general. In this paper, we give an overview of the different battery models that are availabl...

  7. Computable models

    Turner, Raymond

    2009-01-01

    Computational models can be found everywhere in present day science and engineering. In providing a logical framework and foundation for the specification and design of specification languages, Raymond Turner uses this framework to introduce and study computable models. In doing so he presents the first systematic attempt to provide computational models with a logical foundation. Computable models have wide-ranging applications from programming language semantics and specification languages, through to knowledge representation languages and formalism for natural language semantics. They are al

  8. Model Building

    Frampton, Paul H.

    1997-01-01

    In this talk I begin with some general discussion of model building in particle theory, emphasizing the need for motivation and testability. Three illustrative examples are then described. The first is the Left-Right model which provides an explanation for the chirality of quarks and leptons. The second is the 331-model which offers a first step to understanding the three generations of quarks and leptons. Third and last is the SU(15) model which can accommodate the light leptoquarks possibly...

  9. Magnetosphere models

    In this work the most recent magnetospheric models are reviewed. After a short overview of the particle environment, a synthetic survey of the problem is given. For each feature of magnetospheric modelling (boundary, current sheet, ring-current) the approaches used by different authors are described. In the second part a description is given of the magnetospheric models, divided into four groups. In the last part, the different uses of magnetospheric models are illustrated by means of examples

  10. Reorganisation of brain networks in frontotemporal dementia and progressive supranuclear palsy ☆

    Hughes, Laura E.; Ghosh, Boyd C. P.; Rowe, James B.

    2013-01-01

    The disruption of large-scale brain networks is increasingly recognised as a consequence of neurodegenerative dementias. We assessed adults with behavioural variant frontotemporal dementia and progressive supranuclear palsy using magnetoencephalography during an auditory oddball paradigm. Network connectivity among bilateral temporal, frontal and parietal sources was examined using dynamic causal modelling. We found evidence for a systematic change in effective connectivity in both diseases. ...

  11. Phoenix model

    Phoenix (formerly referred to as the Second Generation Model or SGM) is a global general equilibrium model designed to analyze energy-economy-climate related questions and policy implications in the medium- to long-term. This model disaggregates the global economy into 26 industr...

  12. Zeebrugge Model

    Sclütter, Flemming; Frigaard, Peter; Liu, Zhou

    This report presents the model test results on wave run-up on the Zeebrugge breakwater under the simulated prototype storms. The model test was performed in January 2000 at the Hydraulics & Coastal Engineering Laboratory, Aalborg University. The detailed description of the model is given in...

  13. Interface models

    Ravn, Anders P.; Staunstrup, Jørgen

    1994-01-01

    This paper proposes a model for specifying interfaces between concurrently executing modules of a computing system. The model does not prescribe a particular type of communication protocol and is aimed at describing interfaces between both software and hardware modules or a combination of the two....... The model describes both functional and timing properties of an interface...

  14. Hydrological models are mediating models

    Babel, L. V.; Karssenberg, D.

    2013-08-01

    Despite the increasing role of models in hydrological research and decision-making processes, only few accounts of the nature and function of models exist in hydrology. Earlier considerations have traditionally been conducted while making a clear distinction between physically-based and conceptual models. A new philosophical account, primarily based on the fields of physics and economics, transcends classes of models and scientific disciplines by considering models as "mediators" between theory and observations. The core of this approach lies in identifying models as (1) being only partially dependent on theory and observations, (2) integrating non-deductive elements in their construction, and (3) carrying the role of instruments of scientific enquiry about both theory and the world. The applicability of this approach to hydrology is evaluated in the present article. Three widely used hydrological models, each showing a different degree of apparent physicality, are confronted to the main characteristics of the "mediating models" concept. We argue that irrespective of their kind, hydrological models depend on both theory and observations, rather than merely on one of these two domains. Their construction is additionally involving a large number of miscellaneous, external ingredients, such as past experiences, model objectives, knowledge and preferences of the modeller, as well as hardware and software resources. We show that hydrological models convey the role of instruments in scientific practice by mediating between theory and the world. It results from these considerations that the traditional distinction between physically-based and conceptual models is necessarily too simplistic and refers at best to the stage at which theory and observations are steering model construction. The large variety of ingredients involved in model construction would deserve closer attention, for being rarely explicitly presented in peer-reviewed literature. We believe that devoting

  15. Model Selection

    Selén, Yngve

    2004-01-01

    Before using a parametric model one has to be sure that it offers a reasonable description of the system to be modeled. If a bad model structure is employed, the obtained model will also be bad, no matter how good is the parameter estimation method. There exist many possible ways of validating candidate models. This thesis focuses on one of the most common ways, i.e., the use of information criteria. First, some common information criteria are presented, and in the later chapters, various ext...

  16. Cadastral Modeling

    Stubkjær, Erik

    2005-01-01

    Modeling is a term that refers to a variety of efforts, including data and process modeling. The domain to be modeled may be a department, an organization, or even an industrial sector. E-business presupposes the modeling of an industrial sector, a substantial task. Cadastral modeling compares...... to the modeling of an industrial sector, as it aims at rendering the basic concepts that relate to the domain of real estate and the pertinent human activities. The palpable objects are pieces of land and buildings, documents, data stores and archives, as well as persons in their diverse roles as owners, holders...... to land. The paper advances the position that cadastral modeling has to include not only the physical objects, agents, and information sets of the domain, but also the objectives or requirements of cadastral systems....

  17. Modeling Pharmacokinetics.

    Bois, Frederic Y; Brochot, Céline

    2016-01-01

    Pharmacokinetics is the study of the fate of xenobiotics in a living organism. Physiologically based pharmacokinetic (PBPK) models provide realistic descriptions of xenobiotics' absorption, distribution, metabolism, and excretion processes. They model the body as a set of homogeneous compartments representing organs, and their parameters refer to anatomical, physiological, biochemical, and physicochemical entities. They offer a quantitative mechanistic framework to understand and simulate the time-course of the concentration of a substance in various organs and body fluids. These models are well suited for performing extrapolations inherent to toxicology and pharmacology (e.g., between species or doses) and for integrating data obtained from various sources (e.g., in vitro or in vivo experiments, structure-activity models). In this chapter, we describe the practical development and basic use of a PBPK model from model building to model simulations, through implementation with an easily accessible free software. PMID:27311461

  18. ICRF modelling

    This lecture provides a survey of the methods used to model fast magnetosonic wave coupling, propagation, and absorption in tokamaks. The validity and limitations of three distinct types of modelling codes, which will be contrasted, include discrete models which utilize ray tracing techniques, approximate continuous field models based on a parabolic approximation of the wave equation, and full field models derived using finite difference techniques. Inclusion of mode conversion effects in these models and modification of the minority distribution function will also be discussed. The lecture will conclude with a presentation of time-dependent global transport simulations of ICRF-heated tokamak discharges obtained in conjunction with the ICRF modelling codes. 52 refs., 15 figs

  19. Model choice versus model criticism

    Robert, Christian P.; Mengersen, Kerrie; Chen, Carla

    2009-01-01

    The new perspectives on ABC and Bayesian model criticisms presented in Ratmann et al.(2009) are challenging standard approaches to Bayesian model choice. We discuss here some issues arising from the authors' approach, including prior influence, model assessment and criticism, and the meaning of error in ABC.

  20. Ventilation Model

    H. Yang

    1999-11-04

    The purpose of this analysis and model report (AMR) for the Ventilation Model is to analyze the effects of pre-closure continuous ventilation in the Engineered Barrier System (EBS) emplacement drifts and provide heat removal data to support EBS design. It will also provide input data (initial conditions, and time varying boundary conditions) for the EBS post-closure performance assessment and the EBS Water Distribution and Removal Process Model. The objective of the analysis is to develop, describe, and apply calculation methods and models that can be used to predict thermal conditions within emplacement drifts under forced ventilation during the pre-closure period. The scope of this analysis includes: (1) Provide a general description of effects and heat transfer process of emplacement drift ventilation. (2) Develop a modeling approach to simulate the impacts of pre-closure ventilation on the thermal conditions in emplacement drifts. (3) Identify and document inputs to be used for modeling emplacement ventilation. (4) Perform calculations of temperatures and heat removal in the emplacement drift. (5) Address general considerations of the effect of water/moisture removal by ventilation on the repository thermal conditions. The numerical modeling in this document will be limited to heat-only modeling and calculations. Only a preliminary assessment of the heat/moisture ventilation effects and modeling method will be performed in this revision. Modeling of moisture effects on heat removal and emplacement drift temperature may be performed in the future.

  1. Event Modeling

    Bækgaard, Lars

    2001-01-01

    The purpose of this chapter is to discuss conceptual event modeling within a context of information modeling. Traditionally, information modeling has been concerned with the modeling of a universe of discourse in terms of information structures. However, most interesting universes of discourse...... are dynamic and we present a modeling approach that can be used to model such dynamics.We characterize events as both information objects and change agents (Bækgaard 1997). When viewed as information objects events are phenomena that can be observed and described. For example, borrow events in a library can...... temporarily from bookcases to borrowers. When we characterize events as change agents we focus on concepts like transactions, entity processes, and workflow processes....

  2. Event Modeling

    Bækgaard, Lars

    2001-01-01

    The purpose of this chapter is to discuss conceptual event modeling within a context of information modeling. Traditionally, information modeling has been concerned with the modeling of a universe of discourse in terms of information structures. However, most interesting universes of discourse...... are dynamic and we present a modeling approach that can be used to model such dynamics. We characterize events as both information objects and change agents (Bækgaard 1997). When viewed as information objects events are phenomena that can be observed and described. For example, borrow events in a library can...... temporarily from bookcases to borrowers. When we characterize events as change agents we focus on concepts like transactions, entity processes, and workflow processes....

  3. Turbulence modelling

    This paper is an introduction course in modelling turbulent thermohydraulics, aimed at computational fluid dynamics users. No specific knowledge other than the Navier Stokes equations is required beforehand. Chapter I (which those who are not beginners can skip) provides basic ideas on turbulence physics and is taken up in a textbook prepared by the teaching team of the ENPC (Benque, Viollet). Chapter II describes turbulent viscosity type modelling and the 2k-ε two equations model. It provides details of the channel flow case and the boundary conditions. Chapter III describes the 'standard' (Rij-ε) Reynolds tensions transport model and introduces more recent models called 'feasible'. A second paper deals with heat transfer and the effects of gravity, and returns to the Reynolds stress transport model. (author)

  4. Phenomenological models

    Braby, L.A.

    1990-09-01

    The biological effects of ionizing radiation exposure are the result of a complex sequence of physical, chemical, biochemical, and physiological interactions. One way to begin a search for an understanding of health effects of radiation is through the development of phenomenological models of the response. Many models have been presented and tested in the slowly evolving process of characterizing cellular response. A range of models covering different endpoints and phenomena has developed in parallel. Many of these models employ similar assumptions about some underlying processes while differing about the nature of others. An attempt is made to organize many of the models into groups with similar features and to compare the consequences of those features with the actual experimental observations. It is assumed that by showing that some assumptions are inconsistent with experimental observations, the job of devising and testing mechanistic models can be simplified. 43 refs., 13 figs.

  5. Turbulence Model

    Nielsen, Mogens Peter; Shui, Wan; Johansson, Jens

    2011-01-01

    In this report a new turbulence model is presented.In contrast to the bulk of modern work, the model is a classical continuum model with a relatively simple constitutive equation. The constitutive equation is, as usual in continuum mechanics, entirely empirical. It has the usual Newton or Stokes...... term with stresses depending linearly on the strain rates. This term takes into account the transfer of linear momentum from one part of the fluid to another. Besides there is another term, which takes into account the transfer of angular momentum. Thus the model implies a new definition of turbulence....... The model is in a virgin state, but a number of numerical tests have been carried out with good results. It is published to encourage other researchers to study the model in order to find its merits and possible limitations....

  6. Mathematical modelling

    Blomhøj, Morten

    2004-01-01

    Developing competences for setting up, analysing and criticising mathematical models are normally seen as relevant only from and above upper secondary level. The general belief among teachers is that modelling activities presuppose conceptual understanding of the mathematics involved. Mathematical...... modelling, however, can be seen as a practice of teaching that place the relation between real life and mathematics into the centre of teaching and learning mathematics, and this is relevant at all levels. Modelling activities may motivate the learning process and help the learner to establish cognitive...... roots for the construction of important mathematical concepts. In addition competences for setting up, analysing and criticising modelling processes and the possible use of models is a formative aim in this own right for mathematics teaching in general education. The paper presents a theoretical...

  7. Mathematical modelling

    2016-01-01

    This book provides a thorough introduction to the challenge of applying mathematics in real-world scenarios. Modelling tasks rarely involve well-defined categories, and they often require multidisciplinary input from mathematics, physics, computer sciences, or engineering. In keeping with this spirit of modelling, the book includes a wealth of cross-references between the chapters and frequently points to the real-world context. The book combines classical approaches to modelling with novel areas such as soft computing methods, inverse problems, and model uncertainty. Attention is also paid to the interaction between models, data and the use of mathematical software. The reader will find a broad selection of theoretical tools for practicing industrial mathematics, including the analysis of continuum models, probabilistic and discrete phenomena, and asymptotic and sensitivity analysis.

  8. Logistic models

    Sochůrková, Adéla

    2012-01-01

    The aim of this thesis is the compilation of an inventory management methods, describe their principles and assess the appropriateness of their use. In the introductory part of the work, "The nature and importance of inventory management" are briefly described the inventory management, the main objectives of inventory control models, the basic division of inventory species and costs of supply. The following chapter "Overview of inventory control models" includes a breakdown of models from dif...

  9. Why Model?

    Epstein, Joshua M.

    2008-01-01

    This address treats some enduring misconceptions about modeling. One of these is that the goal is always prediction. The lecture distinguishes between explanation and prediction as modeling goals, and offers sixteen reasons other than prediction to build a model. It also challenges the common assumption that scientific theories arise from and 'summarize' data, when often, theories precede and guide data collection; without theory, in other words, it is not clear what data to collect. Among ot...

  10. Mental models

    Marco Antonio Moreira

    1996-12-01

    Full Text Available The mental models subject is presented particularly in the light of Johnson-Laird’s theory. Views from different authors are also presented but the emphasis lies in Johson-Laird’s approach, proposing mental models as a third path in the images x propositions debate. In this perspective, the nature, content, and typology of mental models are discussed, as well as the issue of conciousness and computability. In addition, the methodology of research studies are provided. Essentially, the aim of the paper is to provide an introduction to the mental models topic, having science education research in mind.

  11. Zeebrugge Model

    Liu, Zhou; Frigaard, Peter

    This report presents the model on wave run-up and run-down on the Zeebrugge breakwater under short-crested oblique wave attacks. The model test was performed in March-April 2000 at the Hydraulics & Coastal Engineering Laboratory, Aalborg University.......This report presents the model on wave run-up and run-down on the Zeebrugge breakwater under short-crested oblique wave attacks. The model test was performed in March-April 2000 at the Hydraulics & Coastal Engineering Laboratory, Aalborg University....

  12. Stream Modelling

    Vestergaard, Kristian

    engineers, but as the scale and the complexity of the hydraulic works increased, the mathematical models became so complex that a mathematical solution could not be obtained. This created a demand for new methods and again the experimental investigation became popular, but this time as measurements on small......-scale models. But still the scale and complexity of hydraulic works were increasing, and soon even small-scale models reached a natural limit for some applications. In the mean time the modern computer was developed, and it became possible to solve complex mathematical models by use of computer-based numerical...

  13. Ventilation Model

    The purpose of the Ventilation Model is to simulate the heat transfer processes in and around waste emplacement drifts during periods of forced ventilation. The model evaluates the effects of emplacement drift ventilation on the thermal conditions in the emplacement drifts and surrounding rock mass, and calculates the heat removal by ventilation as a measure of the viability of ventilation to delay the onset of peak repository temperature and reduce its magnitude. The heat removal by ventilation is temporally and spatially dependent, and is expressed as the fraction of heat carried away by the ventilation air compared to the fraction of heat produced by radionuclide decay. One minus the heat removal is called the wall heat fraction, or the remaining amount of heat that is transferred via conduction to the surrounding rock mass. Downstream models, such as the ''Multiscale Thermohydrologic Model'' (BSC 2001), use the wall heat fractions as outputted from the Ventilation Model to initialize their post-closure analyses. The Ventilation Model report was initially developed to analyze the effects of preclosure continuous ventilation in the Engineered Barrier System (EBS) emplacement drifts, and to provide heat removal data to support EBS design. Revision 00 of the Ventilation Model included documentation of the modeling results from the ANSYS-based heat transfer model. The purposes of Revision 01 of the Ventilation Model are: (1) To validate the conceptual model for preclosure ventilation of emplacement drifts and verify its numerical application in accordance with new procedural requirements as outlined in AP-SIII-10Q, Models (Section 7.0). (2) To satisfy technical issues posed in KTI agreement RDTME 3.14 (Reamer and Williams 2001a). Specifically to demonstrate, with respect to the ANSYS ventilation model, the adequacy of the discretization (Section 6.2.3.1), and the downstream applicability of the model results (i.e. wall heat fractions) to initialize post

  14. Modeling Documents with Event Model

    Longhui Wang

    2015-08-01

    Full Text Available Currently deep learning has made great breakthroughs in visual and speech processing, mainly because it draws lessons from the hierarchical mode that brain deals with images and speech. In the field of NLP, a topic model is one of the important ways for modeling documents. Topic models are built on a generative model that clearly does not match the way humans write. In this paper, we propose Event Model, which is unsupervised and based on the language processing mechanism of neurolinguistics, to model documents. In Event Model, documents are descriptions of concrete or abstract events seen, heard, or sensed by people and words are objects in the events. Event Model has two stages: word learning and dimensionality reduction. Word learning is to learn semantics of words based on deep learning. Dimensionality reduction is the process that representing a document as a low dimensional vector by a linear mode that is completely different from topic models. Event Model achieves state-of-the-art results on document retrieval tasks.

  15. Education models

    Poortman, Sybilla; Sloep, Peter

    2006-01-01

    Educational models describes a case study on a complex learning object. Possibilities are investigated for using this learning object, which is based on a particular educational model, outside of its original context. Furthermore, this study provides advice that might lead to an increase in teachers’ motivation for using and sharing learning objects. This document is aimed at teachers and educational designers.

  16. Didactical Modelling

    Højgaard, Tomas; Hansen, Rune

    2016-01-01

    The purpose of this paper is to introduce Didactical Modelling as a research methodology in mathematics education. We compare the methodology with other approaches and argue that Didactical Modelling has its own specificity. We discuss the methodological “why” and explain why we find it useful to...

  17. Neurofuzzy Modelling

    Jantzen, Jan

    1998-01-01

    A neural network can approximate a function, but it is impossible to interpret the result in terms of natural language. The fusion of neural networks and fuzzy logic in neurofuzzy models provide learning as well as readability. Control engineers find this useful, because the models can be...

  18. Martingale Model

    Giandomenico, Rossano

    2006-01-01

    The model determines a stochastic continuous process as continuous limit of a stochastic discrete process so to show that the stochastic continuous process converges to the stochastic discrete process such that we can integrate it. Furthermore, the model determines the expected volatility and the expected mean so to show that the volatility and the mean are increasing function of the time.

  19. Scribe modeller

    Løssing, Ulrik

    1986-01-01

    Ulrik Løssing har redigeret, illustreret og oversat: "Scribe Modeller System, Sheffield, november 1985" af forfatterne: Cedric Green, David Cooper og John Wells.......Ulrik Løssing har redigeret, illustreret og oversat: "Scribe Modeller System, Sheffield, november 1985" af forfatterne: Cedric Green, David Cooper og John Wells....

  20. Animal models

    Gøtze, Jens Peter; Krentz, Andrew

    2014-01-01

    In this issue of Cardiovascular Endocrinology, we are proud to present a broad and dedicated spectrum of reviews on animal models in cardiovascular disease. The reviews cover most aspects of animal models in science from basic differences and similarities between small animals and the human...

  1. Modelling Constructs

    Kindler, Ekkart

    2009-01-01

    There are many different notations and formalisms for modelling business processes and workflows. These notations and formalisms have been introduced with different purposes and objectives. Later, influenced by other notations, comparisons with other tools, or by standardization efforts, these...... notations have been extended in order to increase expressiveness and to be more competitive. This resulted in an increasing number of notations and formalisms for modelling business processes and in an increase of the different modelling constructs provided by modelling notations, which makes it difficult...... to compare modelling notations and to make transformations between them. One of the reasons is that, in each notation, the new concepts are introduced in a different way by extending the already existing constructs. In this chapter, we go the opposite direction: We show that it is possible to add...

  2. Building Models and Building Modelling

    Jørgensen, Kaj Asbjørn; Skauge, Jørn

    teoretiske basis for de kapitler, der har et mere teoretisk indhold. De følgende appendikser B-D indeholder nærmere karakteristika om de to modellerings CAD-programmer ArchiCAD og Architectural Desktop tillige med en sammenligning mellem de to værktøjer. I de resterende to appendikser beskrives de specielle...... problemstillinger vedrørende modellering af de to "Sorthøjparken"-modeller og de resul­terende modeller bliver præsenteret og evalueret. Den samlede rapport er udgivet på projektets hjemmeside: www.iprod.aau.dk/bygit/Web3B/ under Technical Reports....

  3. OSPREY Model

    Veronica J. Rutledge

    2013-01-01

    The absence of industrial scale nuclear fuel reprocessing in the U.S. has precluded the necessary driver for developing the advanced simulation capability now prevalent in so many other countries. Thus, it is essential to model complex series of unit operations to simulate, understand, and predict inherent transient behavior and feedback loops. A capability of accurately simulating the dynamic behavior of advanced fuel cycle separation processes will provide substantial cost savings and many technical benefits. The specific fuel cycle separation process discussed in this report is the off-gas treatment system. The off-gas separation consists of a series of scrubbers and adsorption beds to capture constituents of interest. Dynamic models are being developed to simulate each unit operation involved so each unit operation can be used as a stand-alone model and in series with multiple others. Currently, an adsorption model has been developed within Multi-physics Object Oriented Simulation Environment (MOOSE) developed at the Idaho National Laboratory (INL). Off-gas Separation and REcoverY (OSPREY) models the adsorption of off-gas constituents for dispersed plug flow in a packed bed under non-isothermal and non-isobaric conditions. Inputs to the model include gas, sorbent, and column properties, equilibrium and kinetic data, and inlet conditions. The simulation outputs component concentrations along the column length as a function of time from which breakthrough data is obtained. The breakthrough data can be used to determine bed capacity, which in turn can be used to size columns. It also outputs temperature along the column length as a function of time and pressure drop along the column length. Experimental data and parameters were input into the adsorption model to develop models specific for krypton adsorption. The same can be done for iodine, xenon, and tritium. The model will be validated with experimental breakthrough curves. Customers will be given access to

  4. Graphical Rasch models

    Kreiner, Svend; Christensen, Karl Bang

    Rasch models; Partial Credit models; Rating Scale models; Item bias; Differential item functioning; Local independence; Graphical models......Rasch models; Partial Credit models; Rating Scale models; Item bias; Differential item functioning; Local independence; Graphical models...

  5. Stereometric Modelling

    Grimaldi, P.

    2012-07-01

    These mandatory guidelines are provided for preparation of papers accepted for publication in the series of Volumes of The The stereometric modelling means modelling achieved with : - the use of a pair of virtual cameras, with parallel axes and positioned at a mutual distance average of 1/10 of the distance camera-object (in practice the realization and use of a stereometric camera in the modeling program); - the shot visualization in two distinct windows - the stereoscopic viewing of the shot while modelling. Since the definition of "3D vision" is inaccurately referred to as the simple perspective of an object, it is required to add the word stereo so that "3D stereo vision " shall stand for "three-dimensional view" and ,therefore, measure the width, height and depth of the surveyed image. Thanks to the development of a stereo metric model , either real or virtual, through the "materialization", either real or virtual, of the optical-stereo metric model made visible with a stereoscope. It is feasible a continuous on line updating of the cultural heritage with the help of photogrammetry and stereometric modelling. The catalogue of the Architectonic Photogrammetry Laboratory of Politecnico di Bari is available on line at: http://rappresentazione.stereofot.it:591/StereoFot/FMPro?-db=StereoFot.fp5&-lay=Scheda&-format=cerca.htm&-view

  6. Radarsat-2 Backscattering for the Modeling of Biophysical Parameters of Regenerating Mangrove Forests

    Michele F. Cougo

    2015-12-01

    Full Text Available The aim of this study is to understand the relationship between radar backscattering (σ°, β° and γ of a multi-polarized Radarsat-2 C-band image with the structural attributes of regenerating mangrove vegetation located at the mouth of the Amazon River. CBH (circumference at breast height, height and species data were collected to characterize vegetation structure and above-ground biomass (AGB at 17 plots with a total of 3090 measured individuals. Significant relationships between the linear σ° in VH (vertical transmit, horizontal receive cross-polarization produced r2 values of 0.63 for the average height, 0.53 for the DBH, 0.46 for the basal area (BA and 0.52 for the AGB. Using co-polarized HH (horizontal transmit, horizontal receive and VV (vertical transmit, vertical receive, r2 values increased to 0.81, 0.79, 0.67 and 0.79, respectively. Vegetation attribute maps of average canopy height, DBH and AGB were generated for the study area. We conclude that multi-polarized Radarsat-2 images were adequate for characterization of vegetation attributes in areas of mangrove regeneration.

  7. Model theory

    Hodges, Wilfrid

    1993-01-01

    An up-to-date and integrated introduction to model theory, designed to be used for graduate courses (for students who are familiar with first-order logic), and as a reference for more experienced logicians and mathematicians.

  8. Modeling Arcs

    Insepov, Zeke; Veitzer, Seth; Mahalingam, Sudhakar

    2011-01-01

    Although vacuum arcs were first identified over 110 years ago, they are not yet well understood. We have since developed a model of breakdown and gradient limits that tries to explain, in a self-consistent way: arc triggering, plasma initiation, plasma evolution, surface damage and gra- dient limits. We use simple PIC codes for modeling plasmas, molecular dynamics for modeling surface breakdown, and surface damage, and mesoscale surface thermodynamics and finite element electrostatic codes for to evaluate surface properties. Since any given experiment seems to have more variables than data points, we have tried to consider a wide variety of arcing (rf structures, e beam welding, laser ablation, etc.) to help constrain the problem, and concentrate on common mechanisms. While the mechanisms can be comparatively simple, modeling can be challenging.

  9. Paleoclimate Modeling

    National Oceanic and Atmospheric Administration, Department of Commerce — Computer simulations of past climate. Variables provided as model output are described by parameter keyword. In some cases the parameter keywords are a subset of...

  10. MHD model

    The author's goal is to provide a physical understanding of the ideal MHD model which includes: (1) a basic description of the model, (2) a derivation starting from a more fundamental kinetic model, and (3) a discussion of its range of validity. The ideal MHD model is a single-fluid model that describes the effects of magnetic geometry on the macroscopic equilibrium and stability properties of fusion plasmas. The model is derived in a straight forward manner by forming the mass, momentum, and energy moments of the Boltzmann equation. The moment equations reduce to ideal MHD with the introduction of three critical assumptions: high collisionality, small ion gyro radius, and small resistivity. An analysis of the validity conditions shows that the collision-dominated assumption is never satisfied in plasmas of fusion interest. The remaining two conditions are satisfied by a wide margin. A careful examination of the collision-dominated assumption shows that those particular parts of ideal MHD treated inaccurately (i.e., the parallel momentum and energy equations), play little, if any practical role in MHD equilibrium and stability. These equations primarily describe compression and expansion of a plasma whereas most MHD instabilities involve incompressible motions. The model is incorrect only where it does not matter. This realization leads to the introduction of a modified MHD model known as collisionless MHD which makes predictions nearly identical to collision-dominated assumption. It is thus valid for plasmas of fusion interest. The derivation follows from an analysis of single-particle guiding center motion in a collisionless plasma and the subsequent closure of the system by the heuristic assumption that the motions of interest are incompressible

  11. Accelerated life models modeling and statistical analysis

    Bagdonavicius, Vilijandas

    2001-01-01

    Failure Time DistributionsIntroductionParametric Classes of Failure Time DistributionsAccelerated Life ModelsIntroductionGeneralized Sedyakin's ModelAccelerated Failure Time ModelProportional Hazards ModelGeneralized Proportional Hazards ModelsGeneralized Additive and Additive-Multiplicative Hazards ModelsChanging Shape and Scale ModelsGeneralizationsModels Including Switch-Up and Cycling EffectsHeredity HypothesisSummaryAccelerated Degradation ModelsIntroductionDegradation ModelsModeling the Influence of Explanatory Varia

  12. Model fit and model selection

    Kocherlakota, Narayana R.

    2007-01-01

    This paper uses an example to show that a model that fits the available data perfectly may provide worse answers to policy questions than an alternative, imperfectly fitting model. The author argues that, in the context of Bayesian estimation, this result can be interpreted as being due to the use of an inappropriate prior over the parameters of shock processes. He urges the use of priors that are obtained from explicit auxiliary information, not from the desire to obtain identification.

  13. Model composition in model checking

    Felscher, Ingo

    2014-01-01

    Model-checking allows one to formally check properties of systems: these properties are modeled as logic formulas and the systems as structures like transition systems. These transition systems are often composed, i.e., they arise in form of products or sums. The composition technique allows us to deduce the truth of a formula in the composed system from "interface information": the truth of formulas for the component systems and information in which components which of these formulas hold. W...

  14. Analog model

    The invention relates to devices for modelling the space-dependent kinetics of a nuclear reactor. It can be advantageously used in studying the dynamics of the neutron field in the core to determine the effect of the control rods on the power distribution in the core, for training purposes. The proposed analog model of a nuclear reactor comprises operational amplifiers and a grid of resistors simulating neutron diffusion. Connected to the grid nodes are supply resistors modelling absorption and multiplication of neutrons. This is achieved by that, in the proposed model, all resistors through which power is supplied to the grid nodes are interconnected by their other leads and coupled to the output of the amplifier unit common for all nodes. Therewith, the amlifier unit models the transfer function of a ''point'' reactor. Connected to the input of this unit which includes two to four amplifiers are resistors for addition of signals with a grid node. Coupled to the grid nodes via additional resistors are voltage sources simulating reactivity

  15. Lens Model

    Nash, Ulrik William

    2014-01-01

    Firms consist of people who make decisions to achieve goals. How do these people develop the expectations which underpin the choices they make? The lens model provides one answer to this question. It was developed by cognitive psychologist Egon Brunswik (1952) to illustrate his theory of probabil......Firms consist of people who make decisions to achieve goals. How do these people develop the expectations which underpin the choices they make? The lens model provides one answer to this question. It was developed by cognitive psychologist Egon Brunswik (1952) to illustrate his theory of...... probabilistic functionalism, and concerns the environment and the mind, and adaptation by the latter to the former. This entry is about the lens model, and probabilistic functionalism more broadly. Focus will mostly be on firms and their employees, but, to fully appreciate the scope, we have to keep in mind the...

  16. Persistent Modelling

    2012-01-01

    The relationship between representation and the represented is examined here through the notion of persistent modelling. This notion is not novel to the activity of architectural design if it is considered as describing a continued active and iterative engagement with design concerns – an evident...... characteristic of architectural practice. But the persistence in persistent modelling can also be understood to apply in other ways, reflecting and anticipating extended roles for representation. This book identifies three principle areas in which these extensions are becoming apparent within contemporary....... It also provides critical insight into the use of contemporary modelling tools and methods, together with an examination of the implications their use has within the territories of architectural design, realisation and experience....

  17. Modelling Defiguration

    Bork Petersen, Franziska

    2013-01-01

    focus centres on how the catwalk scenography evokes a ‘defiguration’ of the walking models and to what effect. Vibskov’s mobile catwalk draws attention to the walk, which is a key element of models’ performance but which usually functions in fashion shows merely to present clothes in the most...... advantageous manner. Stepping on the catwalk’s sloping, moving surfaces decelerates the models’ walk and makes it cautious, hesitant and shaky: suddenly the models lack exactly the affirmative, staccato, striving quality of motion, and the condescending expression that they perform on most contemporary...... determines the models’ walk. Furthermore, letting the models set off sound through triggers with attached sound samples gives them an implied agency. This calls into question the designer’s unrestricted authorship....

  18. Inflatable Models

    Ling Li; Vasily Volkov

    2006-01-01

    A physically-based model is presented for the simulation of a new type of deformable objects-inflatable objects, such as shaped balloons, which consist of pressurized air enclosed by an elastic surface. These objects have properties inherent in both 3D and 2D elastic bodies, as they demonstrate the behaviour of 3D shapes using 2D formulations. As there is no internal structure in them, their behaviour is substantially different from the behaviour of deformable solid objects. We use one of the few available models for deformable surfaces, and enhance it to include the forces of internal and external pressure. These pressure forces may also incorporate buoyancy forces, to allow objects filled with a low density gas to float in denser media. The obtained models demonstrate rich dynamic behaviour, such as bouncing, floating, deflation and inflation.

  19. Supernova models

    Recent progress in understanding the observed properties of Type I supernovae as a consequence of the thermonuclear detonation of white dwarf stars and the ensuing decay of the 56Ni produced therein is reviewed. Within the context of this model for Type I explosions and the 1978 model for Type II explosions, the expected nucleosynthesis and gamma-line spectra from both kinds of supernovae are presented. Finally, a qualitatively new approach to the problem of massive star death and Type II supernovae based upon a combination of rotation and thermonuclear burning is discussed

  20. Molecular modeling

    Aarti Sharma

    2009-01-01

    Full Text Available The use of computational chemistry in the development of novel pharmaceuticals is becoming an increasingly important tool. In the past, drugs were simply screened for effectiveness. The recent advances in computing power and the exponential growth of the knowledge of protein structures have made it possible for organic compounds to be tailored to decrease the harmful side effects and increase the potency. This article provides a detailed description of the techniques employed in molecular modeling. Molecular modeling is a rapidly developing discipline, and has been supported by the dramatic improvements in computer hardware and software in recent years.

  1. Cheating models

    Arnoldi, Jakob

    The article discusses the use of algorithmic models for so-called High Frequency Trading (HFT) in finance. HFT is controversial yet widespread in modern financial markets. It is a form of automated trading technology which critics among other things claim can lead to market manipulation. Drawing on...... two cases, this article shows that manipulation more likely happens in the reverse way, meaning that human traders attempt to make algorithms ‘make mistakes’ or ‘mislead’ algos. Thus, it is algorithmic models, not humans, that are manipulated. Such manipulation poses challenges for security exchanges...

  2. Molecular Modeling

    Holmes, Jon L.

    1999-06-01

    Molecular modeling has trickled down from the realm of pharmaceutical and research laboratories into the realm of undergraduate chemistry instruction. It has opened avenues for the visualization of chemical concepts that previously were difficult or impossible to convey. I am sure that many of you have developed exercises using the various molecular modeling tools. It is the desire of this Journal to become an avenue for you to share these exercises among your colleagues. It is to this end that Ron Starkey has agreed to edit such a column and to publish not only the description of such exercises, but also the software documents they use. The WWW is the obvious medium to distribute this combination and so accepted submissions will appear online as a feature of JCE Internet. Typical molecular modeling exercise: finding conformation energies. Molecular Modeling Exercises and Experiments is the latest feature column of JCE Internet, joining Conceptual Questions and Challenge Problems, Hal's Picks, and Mathcad in the Chemistry Curriculum. JCE Internet continues to seek submissions in these areas of interest and submissions of general interest. If you have developed materials and would like to submit them, please see our Guide to Submissions for more information. The Chemical Education Resource Shelf, Equipment Buyers Guide, and WWW Site Review would also like to hear about chemistry textbooks and software, equipment, and WWW sites, respectively. Please consult JCE Internet Features to learn more about these resources at JCE Online. Email Announcements Would you like to be informed by email when the latest issue of the Journal is available online? when a new JCE Software title is shipping? when a new JCE Internet article has been published or is available for Open Review? when your subscription is about to expire? A new feature of JCE Online makes this possible. Visit our Guestbook to learn how. When you submit the form on this page, which includes your email address

  3. Modelling language

    Cardey, Sylviane

    2013-01-01

    In response to the need for reliable results from natural language processing, this book presents an original way of decomposing a language(s) in a microscopic manner by means of intra/inter‑language norms and divergences, going progressively from languages as systems to the linguistic, mathematical and computational models, which being based on a constructive approach are inherently traceable. Languages are described with their elements aggregating or repelling each other to form viable interrelated micro‑systems. The abstract model, which contrary to the current state of the art works in int

  4. Smashnova Model

    Sivaram, C.

    2007-01-01

    An alternate model for gamma ray bursts is suggested. For a white dwarf (WD) and neutron star (NS) very close binary system, the WD (close to Mch) can detonate due to tidal heating, leading to a SN. Material falling on to the NS at relativistic velocities can cause its collapse to a magnetar or quark star or black hole leading to a GRB. As the material smashes on to the NS, it is dubbed the Smashnova model. Here the SN is followed by a GRB. NS impacting a RG (or RSG) (like in Thorne-Zytkow ob...

  5. Defect modelling

    Calculations, drawing principally on developments at AERE Harwell, of the relaxation about lattice defects are reviewed with emphasis on the techniques required for such calculations. The principles of defect modelling are outlined and various programs developed for defect simulations are discussed. Particular calculations for metals, ionic crystals and oxides, are considered. (UK)

  6. Modeling Minds

    Michael, John

    others' minds. Then (2), in order to bring to light some possible justifications, as well as hazards and criticisms of the methodology of looking time tests, I will take a closer look at the concept of folk psychology and will focus on the idea that folk psychology involves using oneself as a model of...

  7. Why Model?

    Olaf eWolkenhauer

    2014-01-01

    Full Text Available Next generation sequencing technologies are bringing about a renaissance of mining approaches. A comprehensive picture of the genetic landscape of an individual patient will be useful, for example, to identify groups of patients that do or do not respond to certain therapies. The high expectations may however not be satisfied if the number of patient groups with similar characteristics is going to be very large. I therefore doubt that mining sequence data will give us an understanding of why and when therapies work. For understanding the mechanisms underlying diseases, an alternative approach is to model small networks in quantitative mechanistic detail, to elucidate the role of gene and proteins in dynamically changing the functioning of cells. Here an obvious critique is that these models consider too few components, compared to what might be relevant for any particular cell function. I show here that mining approaches and dynamical systems theory are two ends of a spectrum of methodologies to choose from. Drawing upon personal experience in numerous interdisciplinary collaborations, I provide guidance on how to model by discussing the question Why model?

  8. Painting models

    Baart, F.; Donchyts, G.; van Dam, A.; Plieger, M.

    2015-12-01

    The emergence of interactive art has blurred the line between electronic, computer graphics and art. Here we apply this art form to numerical models. Here we show how the transformation of a numerical model into an interactive painting can both provide insights and solve real world problems. The cases that are used as an example include forensic reconstructions, dredging optimization, barrier design. The system can be fed using any source of time varying vector fields, such as hydrodynamic models. The cases used here, the Indian Ocean (HYCOM), the Wadden Sea (Delft3D Curvilinear), San Francisco Bay (3Di subgrid and Delft3D Flexible Mesh), show that the method used is suitable for different time and spatial scales. High resolution numerical models become interactive paintings by exchanging their velocity fields with a high resolution (>=1M cells) image based flow visualization that runs in a html5 compatible web browser. The image based flow visualization combines three images into a new image: the current image, a drawing, and a uv + mask field. The advection scheme that computes the resultant image is executed in the graphics card using WebGL, allowing for 1M grid cells at 60Hz performance on mediocre graphic cards. The software is provided as open source software. By using different sources for a drawing one can gain insight into several aspects of the velocity fields. These aspects include not only the commonly represented magnitude and direction, but also divergence, topology and turbulence .

  9. Logic Model

    Taylor, Julie

    2013-01-01

    This paper provides a brief overview of the NSPCC/University of Edinburgh Child Protection Research Centre. It highlights the Centre's work, approach, progress to date and direction of travel. The document includes the Centre's Logic Model which details types of research and outcomes.

  10. Transport modeling

    R.E. Waltz

    2007-01-01

    @@ There has been remarkable progress during the past decade in understanding and modeling turbulent transport in tokamaks. With some exceptions the progress is derived from the huge increases in computational power and the ability to simulate tokamak turbulence with ever more fundamental and physically realistic dynamical equations, e.g.

  11. Model CAPM

    Burianová, Eva

    2008-01-01

    Cílem první části této bakalářské práce je - pomocí analýzy výchozích textů - teoretické shrnutí ekonomických modelů a teorií, na kterých model CAPM stojí: Markowitzův model teorie portfolia (analýza maximalizace očekávaného užitku a na něm založený model výběru optimálního portfolia), Tobina (rozšíření Markowitzova modelu ? rozdělení výběru optimálního portfolia do dvou fází; nejprve určení optimální kombinace rizikových instrumentů a následná alokace dostupného kapitálu mezi tuto optimální ...

  12. Zeebrugge Model

    Jensen, Morten S.; Frigaard, Peter

    In the following, results from model tests with Zeebrugge breakwater are presented. The objective with these tests is partly to investigate the influence on wave run-up due to a changing waterlevel during a storm. Finally, the influence on wave run-up due to an introduced longshore current is...

  13. Modelling Entrepreneurship

    N. Bosma (Niels); G. de Wit (Gerrit); M.A. Carree (Martin)

    2003-01-01

    textabstractTwo approaches can be distinguished with respect to modelling entrepreneurship: (i) the approach focusing on the net development of the number of entrepreneurs in an equilibrium framework and (ii) the approach focusing on the entries and exits of entrepreneurs. In this paper we unify the

  14. Criticality Model

    The ''Disposal Criticality Analysis Methodology Topical Report'' (YMP 2003) presents the methodology for evaluating potential criticality situations in the monitored geologic repository. As stated in the referenced Topical Report, the detailed methodology for performing the disposal criticality analyses will be documented in model reports. Many of the models developed in support of the Topical Report differ from the definition of models as given in the Office of Civilian Radioactive Waste Management procedure AP-SIII.10Q, ''Models'', in that they are procedural, rather than mathematical. These model reports document the detailed methodology necessary to implement the approach presented in the Disposal Criticality Analysis Methodology Topical Report and provide calculations utilizing the methodology. Thus, the governing procedure for this type of report is AP-3.12Q, ''Design Calculations and Analyses''. The ''Criticality Model'' is of this latter type, providing a process evaluating the criticality potential of in-package and external configurations. The purpose of this analysis is to layout the process for calculating the criticality potential for various in-package and external configurations and to calculate lower-bound tolerance limit (LBTL) values and determine range of applicability (ROA) parameters. The LBTL calculations and the ROA determinations are performed using selected benchmark experiments that are applicable to various waste forms and various in-package and external configurations. The waste forms considered in this calculation are pressurized water reactor (PWR), boiling water reactor (BWR), Fast Flux Test Facility (FFTF), Training Research Isotope General Atomic (TRIGA), Enrico Fermi, Shippingport pressurized water reactor, Shippingport light water breeder reactor (LWBR), N-Reactor, Melt and Dilute, and Fort Saint Vrain Reactor spent nuclear fuel (SNF). The scope of this analysis is to document the criticality computational method. The criticality

  15. Criticality Model

    A. Alsaed

    2004-09-14

    The ''Disposal Criticality Analysis Methodology Topical Report'' (YMP 2003) presents the methodology for evaluating potential criticality situations in the monitored geologic repository. As stated in the referenced Topical Report, the detailed methodology for performing the disposal criticality analyses will be documented in model reports. Many of the models developed in support of the Topical Report differ from the definition of models as given in the Office of Civilian Radioactive Waste Management procedure AP-SIII.10Q, ''Models'', in that they are procedural, rather than mathematical. These model reports document the detailed methodology necessary to implement the approach presented in the Disposal Criticality Analysis Methodology Topical Report and provide calculations utilizing the methodology. Thus, the governing procedure for this type of report is AP-3.12Q, ''Design Calculations and Analyses''. The ''Criticality Model'' is of this latter type, providing a process evaluating the criticality potential of in-package and external configurations. The purpose of this analysis is to layout the process for calculating the criticality potential for various in-package and external configurations and to calculate lower-bound tolerance limit (LBTL) values and determine range of applicability (ROA) parameters. The LBTL calculations and the ROA determinations are performed using selected benchmark experiments that are applicable to various waste forms and various in-package and external configurations. The waste forms considered in this calculation are pressurized water reactor (PWR), boiling water reactor (BWR), Fast Flux Test Facility (FFTF), Training Research Isotope General Atomic (TRIGA), Enrico Fermi, Shippingport pressurized water reactor, Shippingport light water breeder reactor (LWBR), N-Reactor, Melt and Dilute, and Fort Saint Vrain Reactor spent nuclear fuel (SNF). The scope of

  16. Information Model for Product Modeling

    焦国方; 刘慎权

    1992-01-01

    The Key problems in product modeling for integrated CAD ∥CAM systems are the information structures and representations of products.They are taking more and more important roles in engineering applications.With the investigation on engineering product information and from the viewpoint of industrial process,in this paper,the information models are proposed and the definitions of the framework of product information are given.And then,the integration and the consistence of product information are discussed by introucing the entity and its instance.As a summary,the information structures described in this paper have many advantage and natures helpful in engineering design.

  17. Molecular Modelling

    Aarti Sharma

    2009-12-01

    Full Text Available

    The use of computational chemistry in the development of novel pharmaceuticals is becoming an increasingly important
    tool. In the past, drugs were simply screened for effectiveness. The recent advances in computing power and
    the exponential growth of the knowledge of protein structures have made it possible for organic compounds to tailored to
    decrease harmful side effects and increase the potency. This article provides a detailed description of the techniques
    employed in molecular modeling. Molecular modelling is a rapidly developing discipline, and has been supported from
    the dramatic improvements in computer hardware and software in recent years.

  18. Leadership model

    Almeida, Leandro S.; José Fernando A. Cruz; Ferreira, Helena Isabel dos Santos Ribeiro; Pinto, Alberto

    2011-01-01

    The Theory of Planned Behavior studies the decision-making mechanisms of individuals. We propose the Nash Equilibria as one, of many, possible mechanisms of transforming human intentions in behavior. This process corresponds to the best strategic individual decision taking in account the collective response. We built a game theoretical model to understand the role of leaders in decision-making of individuals or groups. We study the characteristics of the leaders that can have a...

  19. Model Uncertainty

    Clyde, Merlise; George, Edward I.

    2004-01-01

    The evolution of Bayesian approaches for model uncertainty over the past decade has been remarkable. Catalyzed by advances in methods and technology for posterior computation, the scope of these methods has widened substantially. Major thrusts of these developments have included new methods for semiautomatic prior specification and posterior exploration. To illustrate key aspects of this evolution, the highlights of some of these developments are described.

  20. Supersymmetric models

    This lecture was given at the KEK Summer School on August 3-6, 1993 by Professor N. Sakai. All the available experimental data at low energy can be adequately described by the standard model with SU(3) x SU(2) x U(1) gauge group. The three different gauge coupling constants originate from the three different interactions, namely, strong, weak and electromagnetic interactions. The three interactions described by the three different gauge groups can be truly unified into a single gauge group if a simple gauge group to describe all three interactions is chosen. Even if the grand unified theory is not accepted, the existence of gravitational interaction is sure. There are only two options to explain the gauge hierarchy, that is, technicolor model and supersymmetry. As the introduction to supersymmetry, Spinors and Grassmann number, Supertransformation, unitary representation, chiral scalar superfield and supersymmetric Lagrangian field theory are explained. Regarding the supersymmetric SU(3) x SU(2) x U(1) model, Yukawa coupling and particle content are described. It should be noted that the Higgsino (chiral fermions associated with Higgs scalar) in general introduces anomaly in gauge currents. The simplest way out of such anomaly problem is to introduce Higgsino doublet in pair. (K.I.)

  1. Modeling biomembranes.

    Plimpton, Steven James; Heffernan, Julieanne; Sasaki, Darryl Yoshio; Frischknecht, Amalie Lucile; Stevens, Mark Jackson; Frink, Laura J. Douglas

    2005-11-01

    Understanding the properties and behavior of biomembranes is fundamental to many biological processes and technologies. Microdomains in biomembranes or ''lipid rafts'' are now known to be an integral part of cell signaling, vesicle formation, fusion processes, protein trafficking, and viral and toxin infection processes. Understanding how microdomains form, how they depend on membrane constituents, and how they act not only has biological implications, but also will impact Sandia's effort in development of membranes that structurally adapt to their environment in a controlled manner. To provide such understanding, we created physically-based models of biomembranes. Molecular dynamics (MD) simulations and classical density functional theory (DFT) calculations using these models were applied to phenomena such as microdomain formation, membrane fusion, pattern formation, and protein insertion. Because lipid dynamics and self-organization in membranes occur on length and time scales beyond atomistic MD, we used coarse-grained models of double tail lipid molecules that spontaneously self-assemble into bilayers. DFT provided equilibrium information on membrane structure. Experimental work was performed to further help elucidate the fundamental membrane organization principles.

  2. Ozone modeling

    Exhaust gases from power plants that burn fossil fuels contain concentrations of sulfur dioxide (SO2), nitric oxide (NO), particulate matter, hydrocarbon compounds and trace metals. Estimated emissions from the operation of a hypothetical 500 MW coal-fired power plant are given. Ozone is considered a secondary pollutant, since it is not emitted directly into the atmosphere but is formed from other air pollutants, specifically, nitrogen oxides (NO), and non-methane organic compounds (NMOQ) in the presence of sunlight. (NMOC are sometimes referred to as hydrocarbons, HC, or volatile organic compounds, VOC, and they may or may not include methane). Additionally, ozone formation Alternative is a function of the ratio of NMOC concentrations to NOx concentrations. A typical ozone isopleth is shown, generated with the Empirical Kinetic Modeling Approach (EKMA) option of the Environmental Protection Agency's (EPA) Ozone Isopleth Plotting Mechanism (OZIPM-4) model. Ozone isopleth diagrams, originally generated with smog chamber data, are more commonly generated with photochemical reaction mechanisms and tested against smog chamber data. The shape of the isopleth curves is a function of the region (i.e. background conditions) where ozone concentrations are simulated. The location of an ozone concentration on the isopleth diagram is defined by the ratio of NMOC and NOx coordinates of the point, known as the NMOC/NOx ratio. Results obtained by the described model are presented

  3. Technological Forecasting---Model Selection, Model Stability, and Combining Models

    Nigel Meade; Towhidul Islam

    1998-01-01

    The paper identifies 29 models that the literature suggests are appropriate for technological forecasting. These models are divided into three classes according to the timing of the point of inflexion in the innovation or substitution process. Faced with a given data set and such a choice, the issue of model selection needs to be addressed. Evidence used to aid model selection is drawn from measures of model fit and model stability. An analysis of the forecasting performance of these models u...

  4. Statistical analysis of multipole components in the magnetic field of the RHIC arc regions

    Beebe-Wang,J.; Jain, A.

    2009-05-04

    The existence of multipolar components in the dipole and quadrupole magnets is one of the factors limiting the beam stability in the RHIC operations. Therefore, the statistical properties of the non-linear fields are crucial for understanding the beam behavior and for achieving the superior performance in RHIC. In an earlier work [1], the field quality analysis of the RHIC interaction regions (IR) was presented. Furthermore, a procedure for developing non-linear IR models constructed from measured multipolar data of RHIC IR magnets was described. However, the field quality in the regions outside of the RHIC IR had not yet been addressed. In this paper, we present the statistical analysis of multipolar components in the magnetic fields of the RHIC arc regions. The emphasis is on the lower order components, especially the sextupole in the arc dipole and the 12-pole in the quadrupole magnets, since they are shown to have the strongest effects on the beam stability. Finally, the inclusion of the measured multipolar components data of RHIC arc regions and their statistical properties into tracking models is discussed.

  5. Model Construct Based Enterprise Model Architecture and Its Modeling Approach

    2002-01-01

    In order to support enterprise integration, a kind of model construct based enterprise model architecture and its modeling approach are studied in this paper. First, the structural makeup and internal relationships of enterprise model architecture are discussed. Then, the concept of reusable model construct (MC) which belongs to the control view and can help to derive other views is proposed. The modeling approach based on model construct consists of three steps, reference model architecture synthesis, enterprise model customization, system design and implementation. According to MC based modeling approach a case study with the background of one-kind-product machinery manufacturing enterprises is illustrated. It is shown that proposal model construct based enterprise model architecture and modeling approach are practical and efficient.

  6. Numerical models

    Unnikrishnan, A.S.; Manoj, N.T.

    the wetted perimeter and A the area of cross section (excluding mud flats); C = (1.49/n)R1/6, where n is the Manning coefficient. The numerical scheme used by Harleman and Lee (1969) was used to solve the above equations. In this scheme, the continuity... equation is solved at odd grid points to compute eta at the next time step and the momentum equation is solved at even grid points to compute U . The original scheme of Harleman & Lee (1969) was developed for a single channel. For developing a model...

  7. A Model

    Liu Zhiyang

    2011-01-01

    Similar to ISO Technical Committees,SAC Technical Committees undertake the management and coordination of standard's development and amendments in various sectors in industry,playing the role as a bridge among enterprises,research institutions and the governmental standardization administration.How to fully play the essential role is the vital issue SAC has been committing to resolve.Among hundreds of SAC TCs,one stands out in knitting together those isolated,scattered,but highly competitive enterprises in the same industry with the "Standards" thread,and achieving remarkable results in promoting industry development with standardization.It sets a role model for other TCs.

  8. Scalable improvement of SPME multipolar electrostatics in anisotropic polarizable molecular mechanics using a general short-range penetration correction up to quadrupoles

    Narth, Christophe; Lagardère, Louis; Polack, Etienne; Gresh, Nohad; Wang, Qiantao; Bell, David R.; Rackers, Joshua A.; Ponder, Jay W.; Ren, Pengyu Y.; Piquemal*, Jean-Philip

    2016-01-01

    International audience We propose a general coupling of the Smooth Particle Mesh Ewald (SPME) approach for distributed multipoles to a short-range charge penetration correction modifying the charge-charge, charge-dipole and charge-quadrupole energies. Such an approach significantly improves electrostatics when compared to ab initio values and has been calibrated on Symmetry-Adapted Perturbation Theory (SAPT) reference data. Various neutral molecular dimers have been tested as results on ch...

  9. From model checking to model measuring

    Henzinger, Thomas A.; Otop, Jan

    2013-01-01

    We define the model-measuring problem: given a model $M$ and specification~$\\varphi$, what is the maximal distance $\\rho$ such that all models $M'$ within distance $\\rho$ from $M$ satisfy (or violate)~$\\varphi$. The model measuring problem presupposes a distance function on models. We concentrate on automatic distance functions, which are defined by weighted automata. The model-measuring problem subsumes several generalizations of the classical model-checking problem, in particular, qu...

  10. ModelWizard: Toward Interactive Model Construction

    Hutchison, Dylan

    2016-01-01

    Data scientists engage in model construction to discover machine learning models that well explain a dataset, in terms of predictiveness, understandability and generalization across domains. Questions such as "what if we model common cause Z" and "what if Y's dependence on X reverses" inspire many candidate models to consider and compare, yet current tools emphasize constructing a final model all at once. To more naturally reflect exploration when debating numerous models, we propose an inter...

  11. Towards a Multi Business Model Innovation Model

    Lindgren, Peter; Jørgensen, Rasmus

    2012-01-01

    This paper studies the evolution of business model (BM) innovations related to a multi business model framework. The paper tries to answer the research questions: • What are the requirements for a multi business model innovation model (BMIM)? • How should a multi business model innovation model...... look like? Different generations of BMIMs are initially studied in the context of laying the baseline for how next generation multi BM Innovation model (BMIM) should look like. All generations of models are analyzed with the purpose of comparing the characteristics and challenges of previous...

  12. Better Language Models with Model Merging

    Brants, T

    1996-01-01

    This paper investigates model merging, a technique for deriving Markov models from text or speech corpora. Models are derived by starting with a large and specific model and by successively combining states to build smaller and more general models. We present methods to reduce the time complexity of the algorithm and report on experiments on deriving language models for a speech recognition task. The experiments show the advantage of model merging over the standard bigram approach. The merged model assigns a lower perplexity to the test set and uses considerably fewer states.

  13. Impedance model for nanostructures

    R. S. Akhmedov

    2007-06-01

    Full Text Available The application of the impedance model for nanoelectronic quantum-mechanical structures modelling is described. Characteristics illustrating the efficiency of the model are presented.

  14. Building Mental Models by Dissecting Physical Models

    Srivastava, Anveshna

    2016-01-01

    When students build physical models from prefabricated components to learn about model systems, there is an implicit trade-off between the physical degrees of freedom in building the model and the intensity of instructor supervision needed. Models that are too flexible, permitting multiple possible constructions require greater supervision to…

  15. From Product Models to Product State Models

    Larsen, Michael Holm

    1999-01-01

    A well-known technology designed to handle product data is Product Models. Product Models are in their current form not able to handle all types of product state information. Hence, the concept of a Product State Model (PSM) is proposed. The PSM and in particular how to model a PSM is the Research...

  16. The IMACLIM model; Le modele IMACLIM

    NONE

    2003-07-01

    This document provides annexes to the IMACLIM model which propose an actualized description of IMACLIM, model allowing the design of an evaluation tool of the greenhouse gases reduction policies. The model is described in a version coupled with the POLES, technical and economical model of the energy industry. Notations, equations, sources, processing and specifications are proposed and detailed. (A.L.B.)

  17. Global Business Models

    Rask, Morten

    insight from the literature about business models, international product policy, international entry modes and globalization into a conceptual model of relevant design elements of global business models, enabling global business model innovation to deal with differences in a downstream perspective...

  18. Forward model nonlinearity versus inverse model nonlinearity

    Mehl, S.

    2007-01-01

    The issue of concern is the impact of forward model nonlinearity on the nonlinearity of the inverse model. The question posed is, "Does increased nonlinearity in the head solution (forward model) always result in increased nonlinearity in the inverse solution (estimation of hydraulic conductivity)?" It is shown that the two nonlinearities are separate, and it is not universally true that increased forward model nonlinearity increases inverse model nonlinearity. ?? 2007 National Ground Water Association.

  19. Modeling for Sustainability

    Combemale, Benoit; Cheng, Betty H.C.; Moreira, Ana; Bruel, Jean-Michel; Gray, Jeff

    2015-01-01

    Various disciplines use models for different purposes. An engineering model, including a software engineering model, is often developed to guide the construction of a non-existent system. A scientific model is created to better understand a natural phenomenon (i.e., an already existing system). An engineering model may incorporate scientific models to build a system. Sustainability is an area that requires both types of models. Both engineering and scientific models have been used to support ...

  20. Rotating universe models

    A review is made of some properties of the rotating Universe models. Godel's model is identified as a generalized filted model. Some properties of new solutions of the Einstein's equations, which are rotating non-stationary Universe models, are presented and analyzed. These models have the Godel's model as a particular case. Non-stationary cosmological models are found which are a generalization of the Godel's metrics in an analogous way in which Friedmann is to the Einstein's model. (L.C.)

  1. Concept Modeling vs. Data modeling in Practice

    Madsen, Bodil Nistrup; Erdman Thomsen, Hanne

    2015-01-01

    This chapter shows the usefulness of terminological concept modeling as a first step in data modeling. First, we introduce terminological concept modeling with terminological ontologies, i.e. concept systems enriched with characteristics modeled as feature specifications. This enables a formal...... account of the inheritance of characteristics and allows us to introduce a number of principles and constraints which render concept modeling more coherent than earlier approaches. Second, we explain how terminological ontologies can be used as the basis for developing conceptual and logical data models....... We also show how to map from the various elements in the terminological ontology to elements in the data models, and explain the differences between the models. Finally the usefulness of terminological ontologies as a prerequisite for IT development and data modeling is illustrated with examples from...

  2. Modelling of Hydraulic Robot

    Madsen, Henrik; Zhou, Jianjun; Hansen, Lars Henrik

    1997-01-01

    This paper describes a case study of identifying the physical model (or the grey box model) of a hydraulic test robot. The obtained model is intended to provide a basis for model-based control of the robot. The physical model is formulated in continuous time and is derived by application of the l......This paper describes a case study of identifying the physical model (or the grey box model) of a hydraulic test robot. The obtained model is intended to provide a basis for model-based control of the robot. The physical model is formulated in continuous time and is derived by application...

  3. Auditory evoked fields measured noninvasively with small-animal MEG reveal rapid repetition suppression in the guinea pig

    Christianson, G. B.; Chait, M; De CheveignÉ, A.; Linden, J. F.

    2014-01-01

    In animal models, single-neuron response properties such as stimulus-specific adaptation (SSA) have been described as possible precursors to the mismatch negativity (MMN), a human brain response to stimulus change. Here, we attempt to bridge the gap between human and animal studies by characterising responses to changes in the frequency of repeated tone series in the anaesthetised guinea pig using small-animal magnetoencephalography (MEG). We show that: (1) auditory evoked fields (AEFs) quali...

  4. Non-Gaussian probabilistic MEG source localisation based on kernel density estimation ☆

    Mohseni, Hamid R.; Kringelbach, Morten L.; Woolrich, Mark W; Baker, Adam; Aziz, Tipu Z; Probert-Smith, Penny

    2014-01-01

    There is strong evidence to suggest that data recorded from magnetoencephalography (MEG) follows a non-Gaussian distribution. However, existing standard methods for source localisation model the data using only second order statistics, and therefore use the inherent assumption of a Gaussian distribution. In this paper, we present a new general method for non-Gaussian source estimation of stationary signals for localising brain activity from MEG data. By providing a Bayesian formulation for ME...

  5. Optimal predictive model selection

    Barbieri, Maria Maddalena; Berger, James O.

    2004-01-01

    Often the goal of model selection is to choose a model for future prediction, and it is natural to measure the accuracy of a future prediction by squared error loss. Under the Bayesian approach, it is commonly perceived that the optimal predictive model is the model with highest posterior probability, but this is not necessarily the case. In this paper we show that, for selection among normal linear models, the optimal predictive model is often the median probability model, which is defined a...

  6. Business Model Innovation

    Dodgson, Mark; Gann, David; Phillips, Nelson; Massa, Lorenzo; Tucci, Christopher

    2014-01-01

    The chapter offers a broad review of the literature at the nexus between Business Models and innovation studies, and examines the notion of Business Model Innovation in three different situations: Business Model Design in newly formed organizations, Business Model Reconfiguration in incumbent firms, and Business Model Innovation in the broad context of sustainability. Tools and perspectives to make sense of Business Models and support managers and entrepreneurs in dealing with Business Model ...

  7. Wake modelling combining mesoscale and microscale models

    Badger, Jake; Volker, Patrick; Prospathospoulos, J.; Sieros, G.; Ott, Søren; Réthoré, Pierre-Elouan; Hahmann, Andrea N.; Hasager, Charlotte Bay

    2013-01-01

    In this paper the basis for introducing thrust information from microscale wake models into mesocale model wake parameterizations will be described. A classification system for the different types of mesoscale wake parameterizations is suggested and outlined. Four different mesoscale wake...

  8. Model Manipulation for End-User Modelers

    Acretoaie, Vlad

    , and transformations using their modeling notation and editor of choice. The VM* languages are implemented via a single execution engine, the VM* Runtime, built on top of the Henshin graph-based transformation engine. This approach combines the benefits of flexibility, maturity, and formality. To simplify model editor......End-user modelers are domain experts who create and use models as part of their work. They are typically not Software Engineers, and have little or no programming and meta-modeling experience. However, using model manipulation languages developed in the context of Model-Driven Engineering often...... requires such experience. These languages are therefore only used by a small subset of the modelers that could, in theory, benefit from them. The goals of this thesis are to substantiate this observation, introduce the concepts and tools required to overcome it, and provide empirical evidence in support...

  9. Model Checking of Boolean Process Models

    Schneider, Christoph; Wehler, Joachim

    2011-01-01

    In the field of Business Process Management formal models for the control flow of business processes have been designed since more than 15 years. Which methods are best suited to verify the bulk of these models? The first step is to select a formal language which fixes the semantics of the models. We adopt the language of Boolean systems as reference language for Boolean process models. Boolean systems form a simple subclass of coloured Petri nets. Their characteristics are low tokens to mode...

  10. MODEL VALIDATION AND THE PHILIPPINE PROGRAMMING MODEL

    Rodriguez, Gil R. Jr.; Kunkel, David E.

    1980-01-01

    This research demonstrates the need and the procedure for testing sector programming models It compares the model estimates of endogenous variables to carefully selected base period parameters It uses an operational, static, deterministic, and highly aggregate programming model of Philippine agriculture as the framework Alternative formulations of the Philippine model are also examined for possible errors In the consumption, production, and objective function data sets

  11. Molecular Models: Construction of Models with Magnets

    Kalinovčić P.

    2015-01-01

    Molecular models are indispensable tools in teaching chemistry. Beside their high price, commercially available models are generally too small for classroom demonstration. This paper suggests how to make space-filling (callote) models from Styrofoam with magnetic balls as connectors and disc magnets for showing molecular polarity

  12. QSMSR QUALITATIVE MODEL

    Tahir Abdullah

    2012-02-01

    Full Text Available Software architecture design and requirement engineering are core and independent areas of engineering. A lot of research, education and practice are carried on Requirement elicitation and doing refine it, but it is a major issue of engineering. QSMSR model act as a bridge between requirement and design there is a huge gap between these two areas of software architecture and requirement engineering. The QSMSR model divide into two sub model qualitative model and Principal model in this research we focus on Qualitative model which further divide into two sub models fabricated model and classified model. Classified model make the sub groups of the role and match it with components. The Fabricated model link QSMSR Principal Model to an architecture design. At the end it provides the QSMSR Architecture model of the system as output.

  13. "Bohr's Atomic Model."

    Willden, Jeff

    2001-01-01

    "Bohr's Atomic Model" is a small interactive multimedia program that introduces the viewer to a simplified model of the atom. This interactive simulation lets students build an atom using an atomic construction set. The underlying design methodology for "Bohr's Atomic Model" is model-centered instruction, which means the central model of the…

  14. Model-Independent Diffs

    Könemann, Patrick

    just contain a list of strings, one for each line, whereas the structure of models is defined by their meta models. There are tools available which are able to compute the diff between two models, e.g. RSA or EMF Compare. However, their diff is not model-independent, i.e. it refers to the models it was...

  15. Automated data model evaluation

    Modeling process is essential phase within information systems development and implementation. This paper presents methods and techniques for analysis and evaluation of data model correctness. Recent methodologies and development results regarding automation of the process of model correctness analysis and relations with ontology tools has been presented. Key words: Database modeling, Data model correctness, Evaluation

  16. Modelling Foundations and Applications

    selected from 81 submissions. Papers on all aspects of MDE were received, including topics such as architectural modelling and product lines, code generation, domain-specic modeling, metamodeling, model analysis and verication, model management, model transformation and simulation. The breadth of topics...

  17. Armas estratégicas e poder no sistema internacional: o advento das armas de energia direta e seu impacto potencial sobre a guerra e a distribuição multipolar de capacidades Strategic weapons and power in international system: the arise of direct energy weapons and their potential impact over the war and multipolar distribution of capabilities

    Fabrício Schiavo Ávila

    2009-04-01

    Full Text Available O pós-Guerra Fria (1991-2006 apresenta uma mudança significativa no cenário estratégico: a maior acessibilidade da tecnologia militar e o surgimento de novas armas capazes de modificar o poder coercitivo dos países - como as armas de energia direta - acabam pondo em xeque a ideia de que a primazia nuclear é condição suficiente para garantir a unipolaridade. Focando-se no atual recrudescimento das tensões entre EUA e Rússia - especialmente com a proposta norte-americana de implementação do Escudo Antimíssil no Leste Europeu - e analisando as relações de poder entre os três países, procuramos revelar que tipo de competição ocorrerá no sistema internacional nas próximas décadas. O presente artigo analisa as reais possibilidades de que a primazia nuclear norte-americana se torne efetiva, uma vez que, para tanto, é necessário o desarmamento estratégico das demais potências. Como uma guerra nuclear entre os três países possui um custo político muito elevado, as disputas tendem a ser decididas na esfera das operações. Para ilustrar esta última afirmação, usamos um cenário contrafactual de guerra nuclear limitada entre Estados Unidos, Rússia e China, por meio do qual tentamos evidenciar as precondições táticas e operacionais para uma eventual vitória da coalizão sino-russa.The evolution of the Post-Cold War (1991-2006 international system shows a significant amount of change regarding the strategic capabilities of United States, Russia, and China. The rise of a new class of strategic weapons called directed energy weapons (lasers and high power microwaves, as well as the great costs associated with the quest for nuclear primacy, demand closer examination of the current assumption about the links between nuclear primacy and unipolar distribution of power in the International System. Starting with the current tensions between US and Russia, we try to reveal in this article what kind of competition might be observed in the international system over the next decade. The present work analyzes the real possibilities of the USA achieving an effective nuclear primacy condition, which requires the complete disarmament of all other powers. Since a nuclear war between the three countries has a very high political cost, disputes tend to be settled on the operational sphere. In order to demonstrate this final point, we made comparative use of two nuclear war scenarios. The article concludes by establishing the tactical and operational conditions that Russia and China seems to counting with in order to defeat United States if a shooting war comes.

  18. Environmental Satellite Models for a Macroeconomic Model

    To support national environmental policy, it is desirable to forecast and analyse environmental indicators consistently with economic variables. However, environmental indicators are physical measures linked to physical activities that are not specified in economic models. One way to deal with this is to develop environmental satellite models linked to economic models. The system of models presented gives a frame of reference where emissions of greenhouse gases, acid gases, and leaching of nutrients to the aquatic environment are analysed in line with - and consistently with - macroeconomic variables. This paper gives an overview of the data and the satellite models. Finally, the results of applying the model system to calculate the impacts on emissions and the economy are reviewed in a few illustrative examples. The models have been developed for Denmark; however, most of the environmental data used are from the CORINAIR system implemented in numerous countries

  19. Geologic Framework Model Analysis Model Report

    R. Clayton

    2000-12-19

    The purpose of this report is to document the Geologic Framework Model (GFM), Version 3.1 (GFM3.1) with regard to data input, modeling methods, assumptions, uncertainties, limitations, and validation of the model results, qualification status of the model, and the differences between Version 3.1 and previous versions. The GFM represents a three-dimensional interpretation of the stratigraphy and structural features of the location of the potential Yucca Mountain radioactive waste repository. The GFM encompasses an area of 65 square miles (170 square kilometers) and a volume of 185 cubic miles (771 cubic kilometers). The boundaries of the GFM were chosen to encompass the most widely distributed set of exploratory boreholes (the Water Table or WT series) and to provide a geologic framework over the area of interest for hydrologic flow and radionuclide transport modeling through the unsaturated zone (UZ). The depth of the model is constrained by the inferred depth of the Tertiary-Paleozoic unconformity. The GFM was constructed from geologic map and borehole data. Additional information from measured stratigraphy sections, gravity profiles, and seismic profiles was also considered. This interim change notice (ICN) was prepared in accordance with the Technical Work Plan for the Integrated Site Model Process Model Report Revision 01 (CRWMS M&O 2000). The constraints, caveats, and limitations associated with this model are discussed in the appropriate text sections that follow. The GFM is one component of the Integrated Site Model (ISM) (Figure l), which has been developed to provide a consistent volumetric portrayal of the rock layers, rock properties, and mineralogy of the Yucca Mountain site. The ISM consists of three components: (1) Geologic Framework Model (GFM); (2) Rock Properties Model (RPM); and (3) Mineralogic Model (MM). The ISM merges the detailed project stratigraphy into model stratigraphic units that are most useful for the primary downstream models and the

  20. Geologic Framework Model Analysis Model Report

    The purpose of this report is to document the Geologic Framework Model (GFM), Version 3.1 (GFM3.1) with regard to data input, modeling methods, assumptions, uncertainties, limitations, and validation of the model results, qualification status of the model, and the differences between Version 3.1 and previous versions. The GFM represents a three-dimensional interpretation of the stratigraphy and structural features of the location of the potential Yucca Mountain radioactive waste repository. The GFM encompasses an area of 65 square miles (170 square kilometers) and a volume of 185 cubic miles (771 cubic kilometers). The boundaries of the GFM were chosen to encompass the most widely distributed set of exploratory boreholes (the Water Table or WT series) and to provide a geologic framework over the area of interest for hydrologic flow and radionuclide transport modeling through the unsaturated zone (UZ). The depth of the model is constrained by the inferred depth of the Tertiary-Paleozoic unconformity. The GFM was constructed from geologic map and borehole data. Additional information from measured stratigraphy sections, gravity profiles, and seismic profiles was also considered. This interim change notice (ICN) was prepared in accordance with the Technical Work Plan for the Integrated Site Model Process Model Report Revision 01 (CRWMS M and O 2000). The constraints, caveats, and limitations associated with this model are discussed in the appropriate text sections that follow. The GFM is one component of the Integrated Site Model (ISM) (Figure l), which has been developed to provide a consistent volumetric portrayal of the rock layers, rock properties, and mineralogy of the Yucca Mountain site. The ISM consists of three components: (1) Geologic Framework Model (GFM); (2) Rock Properties Model (RPM); and (3) Mineralogic Model (MM). The ISM merges the detailed project stratigraphy into model stratigraphic units that are most useful for the primary downstream models and

  1. Collaborative networks: Reference modeling

    L.M. Camarinha-Matos; H. Afsarmanesh

    2008-01-01

    Collaborative Networks: Reference Modeling works to establish a theoretical foundation for Collaborative Networks. Particular emphasis is put on modeling multiple facets of collaborative networks and establishing a comprehensive modeling framework that captures and structures diverse perspectives of

  2. Wildfire Risk Main Model

    Earth Data Analysis Center, University of New Mexico — The model combines three modeled fire behavior parameters (rate of spread, flame length, crown fire potential) and one modeled ecological health measure (fire...

  3. Example of a stable wormhole in general relativity

    Bronnikov, K. A.; Lipatova, L. N.; Novikov, I. D.; Shatskiy, A. A.

    2013-01-01

    We study a static, spherically symmetric wormhole model whose metric coincides with that of the so-called Ellis wormhole but the material source of gravity consists of a perfect fluid with negative density and a source-free radial electric or magnetic field. For a certain class of fluid equations of state, it has been shown that this wormhole model is linearly stable under both spherically symmetric perturbations and axial perturbations of arbitrary multipolarity. A similar behavior is predic...

  4. Generalization of GLRT-Based Magnetic Anomaly Detection

    Pepe, Pascal; Zozor, Steeve; Rouve, Laure-Line; Coulomb, Jean-Louis; Servière, Christine; Muley, Jean

    2015-01-01

    International audience Magnetic anomaly detection (MAD) refers to a passive method used to reveal hidden magnetic masses and is most commonly based on a dipolar target model. This paper proposes a generalization of the MAD through a multipolar model that provides a more precise description of the anomaly and serves a twofold objective: to improve the detection performance , and to widen the variety of detectable targets. The dipole detection strategy – namely an orthonormal decomposition o...

  5. LSTM based Conversation Models

    Luan, Yi; Ji, Yangfeng; Ostendorf, Mari

    2016-01-01

    In this paper, we present a conversational model that incorporates both context and participant role for two-party conversations. Different architectures are explored for integrating participant role and context information into a Long Short-term Memory (LSTM) language model. The conversational model can function as a language model or a language generation model. Experiments on the Ubuntu Dialog Corpus show that our model can capture multiple turn interaction between participants. The propos...

  6. Computational neurogenetic modeling

    Benuskova, Lubica

    2010-01-01

    Computational Neurogenetic Modeling is a student text, introducing the scope and problems of a new scientific discipline - Computational Neurogenetic Modeling (CNGM). CNGM is concerned with the study and development of dynamic neuronal models for modeling brain functions with respect to genes and dynamic interactions between genes. These include neural network models and their integration with gene network models. This new area brings together knowledge from various scientific disciplines, such as computer and information science, neuroscience and cognitive science, genetics and molecular biol

  7. TRACKING CLIMATE MODELS

    National Aeronautics and Space Administration — CLAIRE MONTELEONI*, GAVIN SCHMIDT, AND SHAILESH SAROHA* Climate models are complex mathematical models designed by meteorologists, geophysicists, and climate...

  8. Environmental Modeling Center

    Federal Laboratory Consortium — The Environmental Modeling Center provides the computational tools to perform geostatistical analysis, to model ground water and atmospheric releases for comparison...

  9. Combustion modeling in a model combustor

    L.Y.Jiang; I.Campbell; K.Su

    2007-01-01

    The flow-field of a propane-air diffusion flame combustor with interior and exterior conjugate heat transfers was numerically studied.Results obtained from four combustion models,combined with the re-normalization group (RNG) k-ε turbulence model,discrete ordinates radiation model and enhanced wall treatment are presented and discussed.The results are compared with a comprehensive database obtained from a series of experimental measurements.The flow patterns and the recirculation zone length in the combustion chamber are accurately predicted,and the mean axial velocities are in fairly good agreement with the experimental data,particularly at downstream sections for all four combustion models.The mean temperature profiles are captured fairly well by the eddy dissipation (EDS),probability density function (PDF),and laminar flamelet combustion models.However,the EDS-finite-rate combustion model fails to provide an acceptable temperature field.In general,the flamelet model illustrates little superiority over the PDF model,and to some extent the PDF model shows better performance than the EDS model.

  10. ROCK PROPERTIES MODEL ANALYSIS MODEL REPORT

    The purpose of this Analysis and Model Report (AMR) is to document Rock Properties Model (RPM) 3.1 with regard to input data, model methods, assumptions, uncertainties and limitations of model results, and qualification status of the model. The report also documents the differences between the current and previous versions and validation of the model. The rock properties models are intended principally for use as input to numerical physical-process modeling, such as of ground-water flow and/or radionuclide transport. The constraints, caveats, and limitations associated with this model are discussed in the appropriate text sections that follow. This work was conducted in accordance with the following planning documents: WA-0344, ''3-D Rock Properties Modeling for FY 1998'' (SNL 1997, WA-0358), ''3-D Rock Properties Modeling for FY 1999'' (SNL 1999), and the technical development plan, Rock Properties Model Version 3.1, (CRWMS MandO 1999c). The Interim Change Notice (ICNs), ICN 02 and ICN 03, of this AMR were prepared as part of activities being conducted under the Technical Work Plan, TWP-NBS-GS-000003, ''Technical Work Plan for the Integrated Site Model, Process Model Report, Revision 01'' (CRWMS MandO 2000b). The purpose of ICN 03 is to record changes in data input status due to data qualification and verification activities. These work plans describe the scope, objectives, tasks, methodology, and implementing procedures for model construction. The constraints, caveats, and limitations associated with this model are discussed in the appropriate text sections that follow. The work scope for this activity consists of the following: (1) Conversion of the input data (laboratory measured porosity data, x-ray diffraction mineralogy, petrophysical calculations of bound water, and petrophysical calculations of porosity) for each borehole into stratigraphic coordinates; (2) Re-sampling and merging of data sets; (3) Development of geostatistical simulations of porosity; (4

  11. ROCK PROPERTIES MODEL ANALYSIS MODEL REPORT

    Clinton Lum

    2002-02-04

    The purpose of this Analysis and Model Report (AMR) is to document Rock Properties Model (RPM) 3.1 with regard to input data, model methods, assumptions, uncertainties and limitations of model results, and qualification status of the model. The report also documents the differences between the current and previous versions and validation of the model. The rock properties models are intended principally for use as input to numerical physical-process modeling, such as of ground-water flow and/or radionuclide transport. The constraints, caveats, and limitations associated with this model are discussed in the appropriate text sections that follow. This work was conducted in accordance with the following planning documents: WA-0344, ''3-D Rock Properties Modeling for FY 1998'' (SNL 1997, WA-0358), ''3-D Rock Properties Modeling for FY 1999'' (SNL 1999), and the technical development plan, Rock Properties Model Version 3.1, (CRWMS M&O 1999c). The Interim Change Notice (ICNs), ICN 02 and ICN 03, of this AMR were prepared as part of activities being conducted under the Technical Work Plan, TWP-NBS-GS-000003, ''Technical Work Plan for the Integrated Site Model, Process Model Report, Revision 01'' (CRWMS M&O 2000b). The purpose of ICN 03 is to record changes in data input status due to data qualification and verification activities. These work plans describe the scope, objectives, tasks, methodology, and implementing procedures for model construction. The constraints, caveats, and limitations associated with this model are discussed in the appropriate text sections that follow. The work scope for this activity consists of the following: (1) Conversion of the input data (laboratory measured porosity data, x-ray diffraction mineralogy, petrophysical calculations of bound water, and petrophysical calculations of porosity) for each borehole into stratigraphic coordinates; (2) Re-sampling and merging of data sets; (3

  12. Business value modeling based on BPMN models

    Masoumigoudarzi, Farahnaz

    2014-01-01

    In this study we will try to clarify the explanation of modeling and measuring 'Business Values', as it is defined in business context, in the business processes of a company and introduce different methods and select the one which is best for modeling the company's business values. These methods have been used by researchers in business analytics and senior managers of many companies. The focus in this project is business value detection and modeling. The basis of this research is on BPM...

  13. A future of the model organism model

    Rine, Jasper

    2014-01-01

    Changes in technology are fundamentally reframing our concept of what constitutes a model organism. Nevertheless, research advances in the more traditional model organisms have enabled fresh and exciting opportunities for young scientists to establish new careers and offer the hope of comprehensive understanding of fundamental processes in life. New advances in translational research can be expected to heighten the importance of basic research in model organisms and expand opportunities. Howe...

  14. Failure prediction model: Model napovedovanja odpovedi:

    Čelan, Štefan; Težak, Oto; Žižek, Adolf

    2002-01-01

    Preventative maintenance is vital for delicate technical products. Electronic components or the whole system must be changed, and thus need a good model that will indicate failure accurately. In this paper a stochastic stress-strength quantitative model is presented, folowing the five original hypothesis. Proposed new model of failure prediction could be used by the system maintenance. Failure risk could be instantaneosly calculated. The given theory considers the influences of stress on the ...

  15. Better models are more effectively connected models

    Nunes, João Pedro; Bielders, Charles; Darboux, Frederic; Fiener, Peter; Finger, David; Turnbull-Lloyd, Laura; Wainwright, John

    2016-04-01

    The concept of hydrologic and geomorphologic connectivity describes the processes and pathways which link sources (e.g. rainfall, snow and ice melt, springs, eroded areas and barren lands) to accumulation areas (e.g. foot slopes, streams, aquifers, reservoirs), and the spatial variations thereof. There are many examples of hydrological and sediment connectivity on a watershed scale; in consequence, a process-based understanding of connectivity is crucial to help managers understand their systems and adopt adequate measures for flood prevention, pollution mitigation and soil protection, among others. Modelling is often used as a tool to understand and predict fluxes within a catchment by complementing observations with model results. Catchment models should therefore be able to reproduce the linkages, and thus the connectivity of water and sediment fluxes within the systems under simulation. In modelling, a high level of spatial and temporal detail is desirable to ensure taking into account a maximum number of components, which then enables connectivity to emerge from the simulated structures and functions. However, computational constraints and, in many cases, lack of data prevent the representation of all relevant processes and spatial/temporal variability in most models. In most cases, therefore, the level of detail selected for modelling is too coarse to represent the system in a way in which connectivity can emerge; a problem which can be circumvented by representing fine-scale structures and processes within coarser scale models using a variety of approaches. This poster focuses on the results of ongoing discussions on modelling connectivity held during several workshops within COST Action Connecteur. It assesses the current state of the art of incorporating the concept of connectivity in hydrological and sediment models, as well as the attitudes of modellers towards this issue. The discussion will focus on the different approaches through which connectivity

  16. AIDS Epidemiological models

    Rahmani, Fouad Lazhar

    2010-11-01

    The aim of this paper is to present mathematical modelling of the spread of infection in the context of the transmission of the human immunodeficiency virus (HIV) and the acquired immune deficiency syndrome (AIDS). These models are based in part on the models suggested in the field of th AIDS mathematical modelling as reported by ISHAM [6].

  17. Lanchester combat models

    MacKay, N. J.

    2006-01-01

    An overview of Lanchester combat models, emphasising their pedagogical possibilities. After a description of the aimed-fire model and comments on the literature, we introduce briefly a range of further topics: a discrete equivalent, the unaimed-fire model, mixed forces, the meaning of a 'unit', support troops, Bracken's generalization and an asymmetric model.

  18. Lumped-parameter models

    Ibsen, Lars Bo; Liingaard, M.

    2006-12-15

    A lumped-parameter model represents the frequency dependent soil-structure interaction of a massless foundation placed on or embedded into an unbounded soil domain. In this technical report the steps of establishing a lumped-parameter model are presented. Following sections are included in this report: Static and dynamic formulation, Simple lumped-parameter models and Advanced lumped-parameter models. (au)

  19. Animal Models for imaging

    Croft, Barbara Y.

    2002-01-01

    Animal models can be used in the study of disease. This chapter discusses imaging animal models to elucidate the process of human disease. The mouse is used as the primary model. Though this choice simplifies many research choices, it necessitates compromises for in vivo imaging. In the future, we can expect improvements in both animal models and imaging techniques.

  20. Deeper model endgame analysis

    Andrist, Rafael B.; Haworth, Guy McCrossan

    2005-01-01

    A reference model of Fallible Endgame Play has been implemented and exercised with the chess-engine WILHELM. Past experiments have demonstrated the value of the model and the robustness of decisions based on it: experiments agree well with a Markov Model theory. Here, the reference model is exercised on the well-known endgame KBBKN.

  1. Generative Models of Disfluency

    Miller, Timothy A.

    2010-01-01

    This thesis describes a generative model for representing disfluent phenomena in human speech. This model makes use of observed syntactic structure present in disfluent speech, and uses a right-corner transform on syntax trees to model this structure in a very natural way. Specifically, the phenomenon of speech repair is modeled by explicitly…

  2. Modelling Railway Interlocking Systems

    Lindegaard, Morten Peter; Viuf, P.; Haxthausen, Anne Elisabeth

    2000-01-01

    In this report we present a model of interlocking systems, and describe how the model may be validated by simulation. Station topologies are modelled by graphs in which the nodes denote track segments, and the edges denote connectivity for train traÆc. Points and signals are modelled by annotatio...

  3. On Multiobjective Evolution Model

    Ahmed, E; Elettreby, M. F.

    2004-01-01

    Self-Organized Criticality (SOC) phenomena could have a significant effect on the dynamics of ecosystems. The Bak-Sneppen (BS) model is a simple and robust model of biological evolution that exhibits punctuated equilibrium behavior. Here we will introduce random version of BS model. Also we generalize the single objective BS model to a multiobjective one.

  4. On Multiobjective Evolution Model

    Ahmed, E.; Elettreby, M. F.

    Self-Organized Criticality (SOC) phenomena could have a significant effect on the dynamics of ecosystems. The Bak-Sneppen (BS) model is a simple and robust model of biological evolution that exhibits punctuated equilibrium behavior. Here, we will introduce random version of BS model. We also generalize the single objective BS model to a multiobjective one.

  5. Biomass Scenario Model

    2015-09-01

    The Biomass Scenario Model (BSM) is a unique, carefully validated, state-of-the-art dynamic model of the domestic biofuels supply chain which explicitly focuses on policy issues, their feasibility, and potential side effects. It integrates resource availability, physical/technological/economic constraints, behavior, and policy. The model uses a system dynamics simulation (not optimization) to model dynamic interactions across the supply chain.

  6. Masonry behavior and modelling

    Angelillo, Maurizio; Lourenço, Paulo B.; Milani, G.

    2014-01-01

    In this Chapter we present the basic experimental facts on masonry materials and introduce simple and refined models for masonry. The simple models are essentially macroscopic and based on the assumption that the material is incapable of sustaining tensile loads (No-Tension assumption). The refined models account for the microscopic structure of masonry, modeling the interaction between the blocks and the interfaces.

  7. Numerical Modelling of Streams

    Vestergaard, Kristian

    In recent years there has been a sharp increase in the use of numerical water quality models. Numeric water quality modeling can be divided into three steps: Hydrodynamic modeling for the determination of stream flow and water levels. Modelling of transport and dispersion of a conservative...

  8. Wastewater Treatment Models

    Gernaey, Krist; Sin, Gürkan

    2008-01-01

    The state-of-the-art level reached in modeling wastewater treatment plants (WWTPs) is reported. For suspended growth systems, WWTP models have evolved from simple description of biological removal of organic carbon and nitrogen in aeration tanks (ASM1 in 1987) to more advanced levels including...... practice of WWTP modeling by linking the wastewater treatment line with the sludge handling line in one modeling platform. Application of WWTP models is currently rather time consuming and thus expensive due to the high model complexity, and requires a great deal of process knowledge and modeling expertise...

  9. Wastewater treatment models

    Gernaey, Krist; Sin, Gürkan

    2011-01-01

    The state-of-the-art level reached in modeling wastewater treatment plants (WWTPs) is reported. For suspended growth systems, WWTP models have evolved from simple description of biological removal of organic carbon and nitrogen in aeration tanks (ASM1 in 1987) to more advanced levels including...... WWTP modeling by linking the wastewater treatment line with the sludge handling line in one modeling platform. Application of WWTP models is currently rather time consuming and thus expensive due to the high model complexity, and requires a great deal of process knowledge and modeling expertise...

  10. Validation of HEDR models

    The Hanford Environmental Dose Reconstruction (HEDR) Project has developed a set of computer models for estimating the possible radiation doses that individuals may have received from past Hanford Site operations. This document describes the validation of these models. In the HEDR Project, the model validation exercise consisted of comparing computational model estimates with limited historical field measurements and experimental measurements that are independent of those used to develop the models. The results of any one test do not mean that a model is valid. Rather, the collection of tests together provide a level of confidence that the HEDR models are valid

  11. Meta-model Pruning

    Sen S; Moha N.; Baudry B.; Jezequel J.-M.

    2009-01-01

    International audience Large and complex meta-models such as those of Uml and its profiles are growing due to modelling and inter-operability needs of numerous stakeholders. The complexity of such meta-models has led to coining of the term meta-muddle. Individual users often exercise only a small view of a meta-muddle for tasks ranging from model creation to construction of model transformations. What is the effective meta-model that represents this view? We present a flexible meta-model p...

  12. Validation of HEDR models

    The Hanford Environmental Dose Reconstruction (HEDR) Project has developed a set of computer models for estimating the possible radiation doses that individuals may have received from past Hanford Site operations. This document describes the validation of these models. In the HEDR Project, the model validation exercise consisted of comparing computational model predictions with limited historical field measurements and experimental measurements that are independent of those used to develop the models. The results of any one test do not mean that a model is valid. Rather, the collection of tests together provide a level of confidence that the HEDR models are valid

  13. Conceptual Model for Communication

    Fedaghi, Sabah Al; Fadel, Zahraa

    2009-01-01

    A variety of idealized models of communication systems exist, and all may have something in common. Starting with Shannons communication model and ending with the OSI model, this paper presents progressively more advanced forms of modeling of communication systems by tying communication models together based on the notion of flow. The basic communication process is divided into different spheres (sources, channels, and destinations), each with its own five interior stages, receiving, processing, creating, releasing, and transferring of information. The flow of information is ontologically distinguished from the flow of physical signals, accordingly, Shannons model, network based OSI models, and TCP IP are redesigned.

  14. Protein Models Comparator

    Widera, Paweł

    2011-01-01

    The process of comparison of computer generated protein structural models is an important element of protein structure prediction. It has many uses including model quality evaluation, selection of the final models from a large set of candidates or optimisation of parameters of energy functions used in template free modelling and refinement. Although many protein comparison methods are available online on numerous web servers, their ability to handle a large scale model comparison is often very limited. Most of the servers offer only a single pairwise structural comparison, and they usually do not provide a model-specific comparison with a fixed alignment between the models. To bridge the gap between the protein and model structure comparison we have developed the Protein Models Comparator (pm-cmp). To be able to deliver the scalability on demand and handle large comparison experiments the pm-cmp was implemented "in the cloud". Protein Models Comparator is a scalable web application for a fast distributed comp...

  15. Conceptual Model for Communication

    Zahra'a Fadel; Ala'a Alsaqa; Sabah Al-Fedaghi

    2009-01-01

    A variety of idealized models of communication systems exist, and all may have something in common. Starting with Shannon’s communication model and ending with the OSI model, this paper presents progressively more advanced forms of modeling of communication systems by tying communication models together based on the notion of flow. The basic communication process is divided into different spheres (sources, channels, and destinations), each with its own five interior stages: receiving, process...

  16. Dimension of linear models

    Høskuldsson, Agnar

    1996-01-01

    Determination of the proper dimension of a given linear model is one of the most important tasks in the applied modeling work. We consider here eight criteria that can be used to determine the dimension of the model, or equivalently, the number of components to use in the model. Four of these...... the basic problems in determining the dimension of linear models. Then each of the eight measures are treated. The results are illustrated by examples....

  17. Visualizing Risk Prediction Models

    Vanya Van Belle; Ben Van Calster

    2015-01-01

    Objective Risk prediction models can assist clinicians in making decisions. To boost the uptake of these models in clinical practice, it is important that end-users understand how the model works and can efficiently communicate its results. We introduce novel methods for interpretable model visualization. Methods The proposed visualization techniques are applied to two prediction models from the Framingham Heart Study for the prediction of intermittent claudication and stroke after atrial fib...

  18. The monetary policy model

    William Poole

    2006-01-01

    Most monetary economists today conduct their analysis within some version of a rational expectations model. A well-defined equilibrium in such a model requires that the private sector understand policy goals and the policymakers' model of the economy. An austere version of the model, with no information asymmetries, is valid only to a first approximation but nevertheless provides core insights to short- and long-run monetary policy. In this model, effective policy requires clarity of policy g...

  19. Analysis of Business Models

    Slavik Stefan; Bednar Richard

    2014-01-01

    The term business model has been used in practice for few years, but companies create, define and innovate their models subconsciously from the start of business. Our paper is aimed to clear the theory about business model, hence definition and all the components that form each business. In the second part, we create an analytical tool and analyze the real business models in Slovakia and define the characteristics of each part of business model, i.e., customers, distribution, value, resour...

  20. Inference for Multiplicative Models

    Wexler, Ydo; Meek, Christopher

    2012-01-01

    The paper introduces a generalization for known probabilistic models such as log-linear and graphical models, called here multiplicative models. These models, that express probabilities via product of parameters are shown to capture multiple forms of contextual independence between variables, including decision graphs and noisy-OR functions. An inference algorithm for multiplicative models is provided and its correctness is proved. The complexity analysis of the inference algorithm uses a mor...

  1. RIVM Model Catalogue

    Wortelboer FG

    1994-01-01

    This report contains the descriptions of the models currently used within the National Institute of Public Health and Environmental Protection (RIVM). Each model description contains the following entries: Name of the model, Contact in RIVM, Purpose, Policy theme, Technical specifications, Status, Availability, Documentation. Besides, the report contains a list of the models grouped by laboratory, a list of the models grouped by theme, and an index. The purpose of this report is both to give ...

  2. An enhanced communication model

    Flensburg, Per

    2010-01-01

    The concept of information is often taken for more or less granted in research about information systems. This paper introduces a model starting with Shannon and Weaver data transmission model and ends with knowledge transfer between individual persons. The model is in fact an enhanced communication model giving a framework for discussing problems in the communication process. A specific feature of the model is the aim for providing design guidelines in designing the communication process. Th...

  3. Model Driven Language Engineering

    Patrascoiu, Octavian

    2005-01-01

    Modeling is a most important exercise in software engineering and development and one of the current practices is object-oriented (OO) modeling. The Object Management Group (OMG) has defined a standard object-oriented modeling language the Unified Modeling Language (UML). The OMG is not only interested in modeling languages; its primary aim is to enable easy integration of software systems and components using vendor-neutral technologies. This thesis investigates the possibilities for designi...

  4. Latent classification models

    Langseth, Helge; Nielsen, Thomas Dyhre

    2005-01-01

    parametric family ofdistributions.  In this paper we propose a new set of models forclassification in continuous domains, termed latent classificationmodels. The latent classification model can roughly be seen ascombining the \\NB model with a mixture of factor analyzers,thereby relaxing the assumptions of...... classification model, and wedemonstrate empirically that the accuracy of the proposed model issignificantly higher than the accuracy of other probabilisticclassifiers....

  5. Fundamentals of Friction Modeling

    Al-Bender, Farid

    2010-01-01

    This communication presents an overview of friction model-building, which starts from the generic mechanisms behind friction to construct models that simulate observed macroscopic friction behavior. First, basic friction properties are presented. Then, the generic friction model is outlined. Hereafter, simple heuristic/empirical models are discussed, which are suitable for quick simulation and control purposes. An example of these is the Generalized Maxwell-Slip model.

  6. Distilling Model Knowledge

    Papamakarios, George

    2015-01-01

    Top-performing machine learning systems, such as deep neural networks, large ensembles and complex probabilistic graphical models, can be expensive to store, slow to evaluate and hard to integrate into larger systems. Ideally, we would like to replace such cumbersome models with simpler models that perform equally well. In this thesis, we study knowledge distillation, the idea of extracting the knowledge contained in a complex model and injecting it into a more convenient model. We present a ...

  7. QSMSR QUALITATIVE MODEL

    Tahir Abdullah; Shahbaz Nazeer

    2012-01-01

    Software architecture design and requirement engineering are core and independent areas of engineering. A lot of research, education and practice are carried on Requirement elicitation and doing refine it, but it is a major issue of engineering. QSMSR model act as a bridge between requirement and design there is a huge gap between these two areas of software architecture and requirement engineering. The QSMSR model divide into two sub model qualitative model and Principal model in this resear...

  8. Bubble models, data acquisition and model applicability

    Jebavá, Marcela; Kloužek, Jaroslav; Němec, Lubomír

    Vsetín : GLASS SERVICE ,INC, 2005, s. 182-191. ISBN 80-239-4687-0. [International Seminar on Mathematical Modeling and Advanced Numerical Methods in Furnace Design and Operation /8./. Velké Karlovice (CZ), 19.05.2005-20.05.2005] Institutional research plan: CEZ:AV0Z40320502 Keywords : bubble models Subject RIV: CA - Inorganic Chemistry

  9. Standard Model Masses and Models of Nuclei

    Rivero, Alejandro

    2003-01-01

    We note an intriguing coincidence in nuclear levels, that the subshells responsible for doubly magic numbers happen to bracket nuclei at the energies of the Standard Model bosons. This could show that these bosons actually contribute to the effective mesons of nuclear models.

  10. Geochemistry Model Validation Report: External Accumulation Model

    The purpose of this Analysis and Modeling Report (AMR) is to validate the External Accumulation Model that predicts accumulation of fissile materials in fractures and lithophysae in the rock beneath a degrading waste package (WP) in the potential monitored geologic repository at Yucca Mountain. (Lithophysae are voids in the rock having concentric shells of finely crystalline alkali feldspar, quartz, and other materials that were formed due to entrapped gas that later escaped, DOE 1998, p. A-25.) The intended use of this model is to estimate the quantities of external accumulation of fissile material for use in external criticality risk assessments for different types of degrading WPs: U.S. Department of Energy (DOE) Spent Nuclear Fuel (SNF) codisposed with High Level Waste (HLW) glass, commercial SNF, and Immobilized Plutonium Ceramic (Pu-ceramic) codisposed with HLW glass. The scope of the model validation is to (1) describe the model and the parameters used to develop the model, (2) provide rationale for selection of the parameters by comparisons with measured values, and (3) demonstrate that the parameters chosen are the most conservative selection for external criticality risk calculations. To demonstrate the applicability of the model, a Pu-ceramic WP is used as an example. The model begins with a source term from separately documented EQ6 calculations; where the source term is defined as the composition versus time of the water flowing out of a breached waste package (WP). Next, PHREEQC, is used to simulate the transport and interaction of the source term with the resident water and fractured tuff below the repository. In these simulations the primary mechanism for accumulation is mixing of the high pH, actinide-laden source term with resident water; thus lowering the pH values sufficiently for fissile minerals to become insoluble and precipitate. In the final section of the model, the outputs from PHREEQC, are processed to produce mass of accumulation

  11. Pavement Aging Model by Response Surface Modeling

    Manzano-Ramírez A.

    2011-10-01

    Full Text Available In this work, surface course aging was modeled by Response Surface Methodology (RSM. The Marshall specimens were placed in a conventional oven for time and temperature conditions established on the basis of the environment factors of the region where the surface course is constructed by AC-20 from the Ing. Antonio M. Amor refinery. Volatilized material (VM, load resistance increment (ΔL and flow resistance increment (ΔF models were developed by the RSM. Cylindrical specimens with real aging were extracted from the surface course pilot to evaluate the error of the models. The VM model was adequate, in contrast (ΔL and (ΔF models were almost adequate with an error of 20 %, that was associated with the other environmental factors, which were not considered at the beginning of the research.

  12. Model Validation Status Review

    E.L. Hardin

    2001-11-28

    The primary objective for the Model Validation Status Review was to perform a one-time evaluation of model validation associated with the analysis/model reports (AMRs) containing model input to total-system performance assessment (TSPA) for the Yucca Mountain site recommendation (SR). This review was performed in response to Corrective Action Request BSC-01-C-01 (Clark 2001, Krisha 2001) pursuant to Quality Assurance review findings of an adverse trend in model validation deficiency. The review findings in this report provide the following information which defines the extent of model validation deficiency and the corrective action needed: (1) AMRs that contain or support models are identified, and conversely, for each model the supporting documentation is identified. (2) The use for each model is determined based on whether the output is used directly for TSPA-SR, or for screening (exclusion) of features, events, and processes (FEPs), and the nature of the model output. (3) Two approaches are used to evaluate the extent to which the validation for each model is compliant with AP-3.10Q (Analyses and Models). The approaches differ in regard to whether model validation is achieved within individual AMRs as originally intended, or whether model validation could be readily achieved by incorporating information from other sources. (4) Recommendations are presented for changes to the AMRs, and additional model development activities or data collection, that will remedy model validation review findings, in support of licensing activities. The Model Validation Status Review emphasized those AMRs that support TSPA-SR (CRWMS M&O 2000bl and 2000bm). A series of workshops and teleconferences was held to discuss and integrate the review findings. The review encompassed 125 AMRs (Table 1) plus certain other supporting documents and data needed to assess model validity. The AMRs were grouped in 21 model areas representing the modeling of processes affecting the natural and

  13. Model Validation Status Review

    The primary objective for the Model Validation Status Review was to perform a one-time evaluation of model validation associated with the analysis/model reports (AMRs) containing model input to total-system performance assessment (TSPA) for the Yucca Mountain site recommendation (SR). This review was performed in response to Corrective Action Request BSC-01-C-01 (Clark 2001, Krisha 2001) pursuant to Quality Assurance review findings of an adverse trend in model validation deficiency. The review findings in this report provide the following information which defines the extent of model validation deficiency and the corrective action needed: (1) AMRs that contain or support models are identified, and conversely, for each model the supporting documentation is identified. (2) The use for each model is determined based on whether the output is used directly for TSPA-SR, or for screening (exclusion) of features, events, and processes (FEPs), and the nature of the model output. (3) Two approaches are used to evaluate the extent to which the validation for each model is compliant with AP-3.10Q (Analyses and Models). The approaches differ in regard to whether model validation is achieved within individual AMRs as originally intended, or whether model validation could be readily achieved by incorporating information from other sources. (4) Recommendations are presented for changes to the AMRs, and additional model development activities or data collection, that will remedy model validation review findings, in support of licensing activities. The Model Validation Status Review emphasized those AMRs that support TSPA-SR (CRWMS M and O 2000bl and 2000bm). A series of workshops and teleconferences was held to discuss and integrate the review findings. The review encompassed 125 AMRs (Table 1) plus certain other supporting documents and data needed to assess model validity. The AMRs were grouped in 21 model areas representing the modeling of processes affecting the natural and

  14. Product and Process Modelling

    Cameron, Ian T.; Gani, Rafiqul

    This book covers the area of product and process modelling via a case study approach. It addresses a wide range of modelling applications with emphasis on modelling methodology and the subsequent in-depth analysis of mathematical models to gain insight via structural aspects of the models....... These approaches are put into the context of life cycle modelling, where multiscale and multiform modelling is increasingly prevalent in the 21st century. The book commences with a discussion of modern product and process modelling theory and practice followed by a series of case studies drawn from a variety...... to biotechnology applications, food, polymer and human health application areas. The book highlights to important nature of modern product and process modelling in the decision making processes across the life cycle. As such it provides an important resource for students, researchers and industrial practitioners....

  15. Modeling extragalactic bowshocks. I. The model.

    Ferruit, P.; Binette, L.; Sutherland, R. S.; Pecontal, E.

    1997-06-01

    To probe the effects of the nuclear activity on the host galaxy, it is essential to disentangle the relative contribution of shock excitation from that of photoionization. One milestone towards this goal is the ability to model the bowshock structures created by the interaction of radio ejecta with their surrounding medium. We have built a bowshock model based on TDA's one (Taylor, Dyson & Axon, 1992MNRAS.255..351T) which was itself derived from an earlier work on Herbig-Haro objects. Since TDA's original model supplied the astronomers with only [OIII]λ5007 fluxes and profiles for various models of bowshocks, we undertook to include magnetic fields and to incorporate all of the atomic data tables of the code Mappings Ic for the computation of ionization states, cooling rates and line emissivities of the gas. This new model allows us to map line ratios and profiles of extragalactic bowshocks for all major lines of astrophysical interest. In this first paper, we present our model, analyse the gas behavior along the bowshock and give some examples of model results.

  16. On Communication Models

    蒋娜; 谢有琪

    2012-01-01

    With the development of human society, the social hub enlarges beyond one community to the extent that the world is deemed as a community as a whole. Communication, therefore, plays an increasingly important role in our daily life. As a consequence, communication model or the definition of which is not so much a definition as a guide in communication. However, some existed communication models are not as practical as it was. This paper tries to make an overall contrast among three communication models Coded Model, Gable Communication Model and Ostensive Inferential Model, to see how they assist people to comprehend verbal and non -verbal communication.

  17. Towards Approximate Model Transformations

    Troya, Javier; Wimmer, Manuel; Vallecillo, Antonio; Burgueño, Loli

    2014-01-01

    As the size and complexity of models grow, there is a need to count on novel mechanisms and tools for transforming them. This is required, e.g., when model transformations need to provide target models without having access to the complete source models or in really short time—as it happens, e.g., with streaming models—or with very large models for which the transformation algorithms become too slow to be of practical use if the complete population of a model is investigated. In this pa...

  18. Five models of capitalism

    Luiz Carlos Bresser-Pereira

    2012-03-01

    Full Text Available Besides analyzing capitalist societies historically and thinking of them in terms of phases or stages, we may compare different models or varieties of capitalism. In this paper I survey the literature on this subject, and distinguish the classification that has a production or business approach from those that use a mainly political criterion. I identify five forms of capitalism: among the rich countries, the liberal democratic or Anglo-Saxon model, the social or European model, and the endogenous social integration or Japanese model; among developing countries, I distinguish the Asian developmental model from the liberal-dependent model that characterizes most other developing countries, including Brazil.

  19. Microsoft tabular modeling cookbook

    Braak, Paul te

    2013-01-01

    This book follows a cookbook style with recipes explaining the steps for developing analytic data using Business Intelligence Semantic Models.This book is designed for developers who wish to develop powerful and dynamic models for users as well as those who are responsible for the administration of models in corporate environments. It is also targeted at analysts and users of Excel who wish to advance their knowledge of Excel through the development of tabular models or who wish to analyze data through tabular modeling techniques. We assume no prior knowledge of tabular modeling

  20. THE IMPROVED XINANJIANG MODEL

    LI Zhi-jia; YAO Cheng; KONG Xiang-guang

    2005-01-01

    To improve the Xinanjiang model, the runoff generating from infiltration-excess is added to the model.The another 6 parameters are added to Xinanjiang model.In principle, the improved Xinanjiang model can be used to simulate runoff in the humid, semi-humid and also semi-arid regions.The application in Yi River shows the improved Xinanjiang model could forecast discharge with higher accuracy and can satisfy the practical requirements.It also shows that the improved model is reasonable.

  1. Elastic Appearance Models

    Hansen, Mads Fogtmann; Fagertun, Jens; Larsen, Rasmus

    2011-01-01

    This paper presents a fusion of the active appearance model (AAM) and the Riemannian elasticity framework which yields a non-linear shape model and a linear texture model – the active elastic appearance model (EAM). The non-linear elasticity shape model is more flexible than the usual linear...... subspace model, and it is therefore able to capture more complex shape variations. Local rotation and translation invariance are the primary explanation for the additional flexibility. In addition, we introduce global scale invariance into the Riemannian elasticity framework which together with the local...

  2. Flexible survival regression modelling

    Cortese, Giuliana; Scheike, Thomas H; Martinussen, Torben

    2009-01-01

    time-varying effects. The introduced models are all applied to data on breast cancer from the Norwegian cancer registry, and these analyses clearly reveal the shortcomings of Cox's regression model and the need for other supplementary analyses with models such as those we present here.......Regression analysis of survival data, and more generally event history data, is typically based on Cox's regression model. We here review some recent methodology, focusing on the limitations of Cox's regression model. The key limitation is that the model is not well suited to represent time...

  3. Energy-consumption modelling

    Reiter, E.R.

    1980-01-01

    A highly sophisticated and accurate approach is described to compute on an hourly or daily basis the energy consumption for space heating by individual buildings, urban sectors, and whole cities. The need for models and specifically weather-sensitive models, composite models, and space-heating models are discussed. Development of the Colorado State University Model, based on heat-transfer equations and on a heuristic, adaptive, self-organizing computation learning approach, is described. Results of modeling energy consumption by the city of Minneapolis and Cheyenne are given. Some data on energy consumption in individual buildings are included.

  4. Modelling farmers' labour supply in CGE models

    Gaasland, Ivar

    2008-01-01

    In most CGE models with special focus on farm policy, the on-farm wage either follows the ordinary wage in the economy or it is varies according to an assumption of sector specific farm labour. This paper demonstrates a practical and empirical consistent way to model farm household allocation of labour in CGE models, assuming that farm labour is partially sector specific. In this set up, preferences for farming and the relative wage between on-farm and off-farm work, determines the allocation...

  5. Modeling Guru: Knowledge Base for NASA Modelers

    Seablom, M. S.; Wojcik, G. S.; van Aartsen, B. H.

    2009-05-01

    Modeling Guru is an on-line knowledge-sharing resource for anyone involved with or interested in NASA's scientific models or High End Computing (HEC) systems. Developed and maintained by the NASA's Software Integration and Visualization Office (SIVO) and the NASA Center for Computational Sciences (NCCS), Modeling Guru's combined forums and knowledge base for research and collaboration is becoming a repository for the accumulated expertise of NASA's scientific modeling and HEC communities. All NASA modelers and associates are encouraged to participate and provide knowledge about the models and systems so that other users may benefit from their experience. Modeling Guru is divided into a hierarchy of communities, each with its own set forums and knowledge base documents. Current modeling communities include those for space science, land and atmospheric dynamics, atmospheric chemistry, and oceanography. In addition, there are communities focused on NCCS systems, HEC tools and libraries, and programming and scripting languages. Anyone may view most of the content on Modeling Guru (available at http://modelingguru.nasa.gov/), but you must log in to post messages and subscribe to community postings. The site offers a full range of "Web 2.0" features, including discussion forums, "wiki" document generation, document uploading, RSS feeds, search tools, blogs, email notification, and "breadcrumb" links. A discussion (a.k.a. forum "thread") is used to post comments, solicit feedback, or ask questions. If marked as a question, SIVO will monitor the thread, and normally respond within a day. Discussions can include embedded images, tables, and formatting through the use of the Rich Text Editor. Also, the user can add "Tags" to their thread to facilitate later searches. The "knowledge base" is comprised of documents that are used to capture and share expertise with others. The default "wiki" document lets users edit within the browser so others can easily collaborate on the

  6. Empirical Model Building Data, Models, and Reality

    Thompson, James R

    2011-01-01

    Praise for the First Edition "This...novel and highly stimulating book, which emphasizes solving real problems...should be widely read. It will have a positive and lasting effect on the teaching of modeling and statistics in general." - Short Book Reviews This new edition features developments and real-world examples that showcase essential empirical modeling techniques Successful empirical model building is founded on the relationship between data and approximate representations of the real systems that generated that data. As a result, it is essential for researchers who construct these m

  7. Major Differences between the Jerome Model and the Horace Model

    朱艳

    2014-01-01

    There are three famous translation models in the field of translation: the Jerome model, the Horace model and the Schleiermacher model. The production and development of the three models have significant influence on the translation. To find the major differences between the two western classical translation theoretical models, we discuss the Jerome model and the Hor-ace model deeply in this paper.

  8. Biosphere Model Report

    D.W. Wu; A.J. Smith

    2004-11-08

    The purpose of this report is to document the biosphere model, the Environmental Radiation Model for Yucca Mountain, Nevada (ERMYN), which describes radionuclide transport processes in the biosphere and associated human exposure that may arise as the result of radionuclide release from the geologic repository at Yucca Mountain. The biosphere model is one of the process models that support the Yucca Mountain Project (YMP) Total System Performance Assessment (TSPA) for the license application (LA), TSPA-LA. The ERMYN provides the capability of performing human radiation dose assessments. This report documents the biosphere model, which includes: (1) Describing the reference biosphere, human receptor, exposure scenarios, and primary radionuclides for each exposure scenario (Section 6.1); (2) Developing a biosphere conceptual model using site-specific features, events, and processes (FEPs) (Section 6.2), the reference biosphere (Section 6.1.1), the human receptor (Section 6.1.2), and approximations (Sections 6.3.1.4 and 6.3.2.4); (3) Building a mathematical model using the biosphere conceptual model (Section 6.3) and published biosphere models (Sections 6.4 and 6.5); (4) Summarizing input parameters for the mathematical model, including the uncertainty associated with input values (Section 6.6); (5) Identifying improvements in the ERMYN compared with the model used in previous biosphere modeling (Section 6.7); (6) Constructing an ERMYN implementation tool (model) based on the biosphere mathematical model using GoldSim stochastic simulation software (Sections 6.8 and 6.9); (7) Verifying the ERMYN by comparing output from the software with hand calculations to ensure that the GoldSim implementation is correct (Section 6.10); (8) Validating the ERMYN by corroborating it with published biosphere models; comparing conceptual models, mathematical models, and numerical results (Section 7).

  9. Biosphere Model Report

    The purpose of this report is to document the biosphere model, the Environmental Radiation Model for Yucca Mountain, Nevada (ERMYN), which describes radionuclide transport processes in the biosphere and associated human exposure that may arise as the result of radionuclide release from the geologic repository at Yucca Mountain. The biosphere model is one of the process models that support the Yucca Mountain Project (YMP) Total System Performance Assessment (TSPA) for the license application (LA), TSPA-LA. The ERMYN provides the capability of performing human radiation dose assessments. This report documents the biosphere model, which includes: (1) Describing the reference biosphere, human receptor, exposure scenarios, and primary radionuclides for each exposure scenario (Section 6.1); (2) Developing a biosphere conceptual model using site-specific features, events, and processes (FEPs) (Section 6.2), the reference biosphere (Section 6.1.1), the human receptor (Section 6.1.2), and approximations (Sections 6.3.1.4 and 6.3.2.4); (3) Building a mathematical model using the biosphere conceptual model (Section 6.3) and published biosphere models (Sections 6.4 and 6.5); (4) Summarizing input parameters for the mathematical model, including the uncertainty associated with input values (Section 6.6); (5) Identifying improvements in the ERMYN compared with the model used in previous biosphere modeling (Section 6.7); (6) Constructing an ERMYN implementation tool (model) based on the biosphere mathematical model using GoldSim stochastic simulation software (Sections 6.8 and 6.9); (7) Verifying the ERMYN by comparing output from the software with hand calculations to ensure that the GoldSim implementation is correct (Section 6.10); (8) Validating the ERMYN by corroborating it with published biosphere models; comparing conceptual models, mathematical models, and numerical results (Section 7)

  10. A Measurement of Primordial Non-Gaussianity Using WMAP 5-Year Temperature Skewness Power Spectrum

    Smidt, Joseph; Amblard, Alexandre; Serra, Paolo; Cooray, Asantha

    2009-01-01

    We constrain the primordial non-Gaussianity parameter of the local model f_{NL} using the skewness power spectrum associated with the two-to-one cumulant correlator of cosmic microwave background temperature anisotropies. This bispectrum-related power spectrum was constructed after weighting the temperature map with the appropriate window functions to form an estimator that probes the multipolar dependence of the underlying bispectrum associated with the primordial non-Gaussianity. We also es...

  11. What controls the large-scale magnetic fields of M dwarfs?

    Gastine, T.; Morin, J.; Duarte, L.; Reiners, A; Christensen, U; Wicht, J

    2013-01-01

    Observations of active M dwarfs show a broad variety of large-scale magnetic fields encompassing dipole-dominated and multipolar geometries. We detail the analogy between some anelastic dynamo simulations and spectropolarimetric observations of 23 M stars. In numerical models, the relative contribution of inertia and Coriolis force in the global force balance -estimated by the so-called local Rossby number- is known to have a strong impact on the magnetic field geometry. We discuss the releva...

  12. New Modes of Nuclear Excitations

    Tsoneva Nadia; Lenske Horst

    2013-01-01

    We present a theoretical approach based on density functional theory supplemented by a microscopic multi-phonon model which is applied for investigations of pygmy resonances and other excitations of different multipolarities in stable and exotic nuclei. The possible relation of low-energy modes to the properties of neutron or proton skins is systematically studied in isotonic and isotopic chains. The fine structure of nuclear electric and magnetic response functions is analyzed and compared t...

  13. Nonlinear Modeling by Assembling Piecewise Linear Models

    Yao, Weigang; Liou, Meng-Sing

    2013-01-01

    To preserve nonlinearity of a full order system over a parameters range of interest, we propose a simple modeling approach by assembling a set of piecewise local solutions, including the first-order Taylor series terms expanded about some sampling states. The work by Rewienski and White inspired our use of piecewise linear local solutions. The assembly of these local approximations is accomplished by assigning nonlinear weights, through radial basis functions in this study. The efficacy of the proposed procedure is validated for a two-dimensional airfoil moving at different Mach numbers and pitching motions, under which the flow exhibits prominent nonlinear behaviors. All results confirm that our nonlinear model is accurate and stable for predicting not only aerodynamic forces but also detailed flowfields. Moreover, the model is robustness-accurate for inputs considerably different from the base trajectory in form and magnitude. This modeling preserves nonlinearity of the problems considered in a rather simple and accurate manner.

  14. Modeling agriculture in the Community Land Model

    B. Drewniak; Song, J.(Pusan National University, Pusan, South Korea); Prell, J.; Kotamarthi, V. R.; Jacob, R.

    2012-01-01

    The potential impact of climate change on agriculture is uncertain. In addition, agriculture could influence above- and below-ground carbon storage. Development of models that represent agriculture is necessary to address these impacts. We have developed an approach to integrate agriculture representations for three crop types – maize, soybean, and spring wheat – into the coupled carbon-nitrogen version of the Community Land Model (CLM), to help address these questions. Here we present the...

  15. Modeling agriculture in the Community Land Model

    B. Drewniak; Song, J.(Pusan National University, Pusan, South Korea); Prell, J.; Kotamarthi, V. R.; Jacob, R.

    2013-01-01

    The potential impact of climate change on agriculture is uncertain. In addition, agriculture could influence above- and below-ground carbon storage. Development of models that represent agriculture is necessary to address these impacts. We have developed an approach to integrate agriculture representations for three crop types – maize, soybean, and spring wheat – into the coupled carbon–nitrogen version of the Community Land Model (CLM), to help address these questions. Here we present the ne...

  16. OPEC model : adjustment or new model

    Since the early eighties, the international oil industry went through major changes : new financial markets, reintegration, opening of the upstream, liberalization of investments, privatization. This article provides answers to two major questions : what are the reasons for these changes ? ; do these changes announce the replacement of OPEC model by a new model in which state intervention is weaker and national companies more autonomous. This would imply a profound change of political and institutional systems of oil producing countries. (Author)

  17. Solid Waste Projection Model: Model user's guide

    The Solid Waste Projection Model (SWPM) system is an analytical tool developed by Pacific Northwest Laboratory (PNL) for Westinghouse Hanford company (WHC) specifically to address solid waste management issues at the Hanford Central Waste Complex (HCWC). This document, one of six documents supporting the SWPM system, contains a description of the system and instructions for preparing to use SWPM and operating Version 1 of the model. 4 figs., 1 tab

  18. A costal dispersion model

    A dispersion model to be used off costal waters has been developed. The model has been applied to describe the migration of radionuclides in the Baltic sea. A summary of the results is presented here. (K.A.E)

  19. Modeling Infectious Diseases

    ... Background Information > Modeling Infectious Diseases Fact Sheet Modeling Infectious Diseases Fact Sheet Tagline (Optional) Using computers to prepare ... Content Area Predicting the potential spread of an infectious disease requires much more than simply connecting cities on ...

  20. LAT Background Models

    National Aeronautics and Space Administration — The Galactic model is a spatial and spectral template. The model for the Galactic diffuse emission was developed using spectral line surveys of HI and CO (as a...