1,891 research outputs found
Convergence of Pyramidal and Medial Brain Stem Descending Pathways Onto Macaque Cervical Spinal Interneurons
No full textRiddle CN, Baker SN. Convergence of pyramidal and medial brain stem descending pathways onto macaque cervical spinal interneurons. J Neurophysiol 103: 2821-2832, 2010. First published March 24, 2010; doi: 10.1152/jn.00491.2009. We investigated the control of spinal interneurons by corticospinal and medial brain stem descending tracts in two macaque monkeys. Stimulating electrodes were implanted in the left pyramidal tract (PT), and the right medial longitudinal fasciculus (MLF), which contains reticulospinal, vestibulospinal, and some tectospinal fibers. Single unit discharge was recorded from 163 interneurons in the intermediate zone of the right spinal cord (segmental levels C-6-C-8) in the awake state; inputs from descending pathways were assessed from the responses to stimulation through the PT and MLF electrodes. Convergent input from both pathways was the most common finding (71/163 cells); responses to PT and MLF stimulation were of similar amplitude. Interneuron discharge was also recorded while the animal performed a reach and grasp task with the right hand; the output connections of the recorded cells were determined by delivering intraspinal microstimulation (ISMS) at the recording sites. Convergent input from MLF/PT stimulation was also common when analysis was restricted to cells that increased their rate during grasp (14/23 cells) or to cells recorded at sites where ISMS elicited finger or wrist movements (23/57 cells). We conclude that medial brain stem and corticospinal descending pathways have largely overlapping effects on spinal interneurons, including those involved in the control of the hand. This may imply a more important role for the brain stem in coordinating hand movements in primates than commonly assumed; brain stem pathways could contribute to the restoration of function seen after lesions to the corticospinal tract
Topological duality on the function space H(CN)
No full textBy a classical theorem, there is an isomorphism between the space of entire functions of exponential type on Cn,ExpCn, and the analytic functions on H(Cn),H′(Cn) [see, for example, F. Trèves, Topological vector spaces, distributions, and kernels, Academic Press, New York, 1967; MR0225131 (37 #726)]. In this note, the author extends this useful theorem to H(CN), the space of analytic functions on the countable product of complex lines. Specifically, he considers H(CN) endowed with the compact-open topology τ0 and the associated bornological topology τδ. For both τ=τ0 and τδ, the author characterizes the strong duals (H(CN),τ)′ as spaces of entire functions of exponential type on CN. {Reviewer's remark: In the meantime the author has shown (private communication) that these dual spaces are different.}Depto. de Análisis Matemático y Matemática AplicadaFac. de Ciencias MatemáticasTRUEpu
Structural and transport properties of neutral radical crystals of Co-III(tmp)(CN)(2) (tmp=5,10,15,20-tetramethylporphyrinato) and the CN-bridged polymer [Co-III( tmp)(CN)](n)
No full textAn axially ligated Co(tmp) (tmp = 5,10,15,20-tetramethylporphyrinato) anion, [Co-III(tmp)(CN)(2)](-), has been prepared and subjected to electrochemical oxidation to obtain the open shell tmp pi-ligand. With acetone as the solvent, solvent-free neutral radical crystals of Co-III(tmp)(CN)(2) are obtained, whereas solvent-inclusive crystals of Co-III(tmp)(CN)(2)center dot 2CH(3)CN are obtained with CH3CN as the solvent. In both crystals, the open shell tmp ring deforms into a ruffled form, which makes the pi-pi interactions in the crystal weak. Thus, the electrical conductivity is low, and the crystals behave as semiconductors with a room temperature resistivity of 10(6) Omega cm and an activation energy of about 0.3 eV. When the solvent is acetone, non-oxidized crystals of the CN-bridged polymer {[Co-III(tmp)(CN)](acetone)}(n) are obtained as a byproduct. The closed shell tmp ring deforms into a ruffled form, and there pi-pi interactions in the crystal are negligible. The room temperature resistivity is rather high at about 10(8) Omega cm
Isovariant maps from free Cn-manifolds to representation spheres
No full textAbstractThe isovariant version of Borsuk–Ulam type theorems has been studied by Wasserman and the first author. In this paper, first we consider the relation between the existence of Cn-isovariant maps from free Cn-manifolds to representation spheres and Borsuk–Ulam type inequalities for their dimensions. Our main result classifies the Cn-isovariant maps by Cn-isovariant homotopy types when a Borsuk–Ulam type inequality holds. For proving it, we use the multidegree of a Cn-equivariant map developed by the first author
Investigation of the interaction between corticomuscular coherence, motor precision and perceived difficulty in wrist flexion and extension
No full textIncludes abstract.Includes bibliographical references.Recently, behavioural (motor precision) differences were reported between isometric wrist flexion and extension. Neurophysiological as well as clinical differences have also been reported between these antagonistic movements. Corticomuscular coherence (CMC), i.e. the frequency specific temporal coupling between the electroencephalogram (EEG) and electromyogram (EMG) recorded during isometric force production, reflects the functional connectivity between cortex and muscle. A single muscle (flexor digitorum superficialis) study suggests a positive correlation between 15-35 Hz (beta) CMC and motor precision of the muscle. Yet, no study has simultaneously compared CMC and motor precision between wrist flexion and extension. Task perceived difficulty, which is a perceptual variable, may influence both motor precision and CMC, but has not been studied yet. The main aim of the present study was to investigate the interaction between CMC, motor precision and perceived difficulty in isometric wrist flexion and extension tasks
Differential Spectral Imaging of the CN Violet Band in Laser-Induced Plasmas on TNT Simulant Molecules
No full textDual channel emission imaging of m-nitrobenzoic acid and benzoic acid was performed in order to visualize the morphology of the CN violet band emission of a TNT analogue. The CN channel was corrected for continuum emission using a simultaneously imaged background channel. Simultaneous dual channel imaging alleviated problems with shot to shot variation in the plasma morphology due to the friable substrates and showed differences between plasmas formed on the two targets
ELECTRONIC SPECTROSCOPY AND PREDISSOCIATION DYNAMICS OF Ne-CN
No full textAuthor Institution: Department of Chemistry, Emory UniversityIn previous work we have recorded and analyzed three bands of Ne-CN which were associated with the CN B-X 0-0 transition. These features were assigned to the electronic origin and two internal rotor levels [Y. Lin and M. C. Heaven, J. Chen. Phys. 94, 5765(1991)]. More recently we have re-examined the spectrum in the vicinity of the CN 0-0 transition, and recorded spectra for the bands associated with the CN 1-0 transition. Ten previously unobserved bands have been characterized. Features corresponding to multiple excitations of the internal rotor mode, and excitation of the CN-Ne stretch, are present. We are in the process of fitting a two-dimensional potential energy surface to this date. A search for Ne-CN bands associated with the CN 3-0 transition was made. A single feature, with a homogenously broadened national envelope, was observed next to the CN , 3-0, R(1) line. Complex features associated with the transition could not be found. A possible explanation for these results in that is subject to rapid predissociations caused by spin-orbit relaxation and internal conversion. The fact that fluorescence cannot be seen following excitation of the lower energy spin-orbit component suggests that internal conversion is much faster that A state radiative decay. Observation of fluorescence following excitation of the higher energy spin-orbit component would then imply that spin-orbit relaxation ) is much faster that internal conversion. These speculations are being explored in a series of opticalûoptical double resonance experiments
INSTABILITIES IN THE ELPASOLITE STRUCTURES: AND
No full textAuthor Institution: Department of Chemistry, The University of TexasThe structural phase transformations in and have been probed using Raman scattering and optical microscopy. The salt undergoes two phase transformations while the salt is observed optically to have one phase change . The phase change in the salt is 1st order involving rotation of the octahedra. The transition is 2nd order with the structural distortion proceeding along a soft translational mode. The phase transformation in involves a simultaneous distortion among the same two phonons. The structural instabilities for these two salts are the same as those observed for other salts indicating that materials with the elpasolite structure may share a common lattice instability. The transition temperatures for salts correlate with the size of the site, as is consistent with the earlier suggestion that the major driving force for the instabilities in these materials results from atoms occupying too large a site in the cubic lattice. As the site size decreases, the high temperature cubic cell is stabilized thereby lowering the critical temperatures for the phase transformations. The correlation of site size and the critical temperature is not maintained in comparison of the and salts. The unusual behavior of the material has been attributed to a cooperative interaction of the external phonon instabilities with the internal forces of the complexion
Spectral Characteristics of CN Radical (B -> X) and Its Application in Determination of Rotational and Vibrational Temperatures of Plasma
No full textThe aim is to resolve the difficulties of measurement of temperature at several thousands of Celsius degrees for some unstable non-equilibrium gas flows. Based on the molecular spectroscopy theory and inherent molecular structure characteristics of the CN radical, the dependence of the spectral profile on the rotational temperature (RT), vibrational temperature (VT) and optical apparatus function are numerically explored within some certain ranges. Meanwhile, by comparing the numerically calculated spectra with the experimental spectra of the CN radical, the corresponding RT and VT of the plasma induced by the interaction of the laser pulse from an oscillated Nd:YAG laser with the coal target are determined, respectively. In addition, a short discussion on the thermodynamic state and the energy transfer process of the CN radical is also given
Eastern Europe's experience with banking reform : is there a role for banks in the transition?
No full textAre there lessons to be learned about how Eastern European countries have dealt with problems in their banking systems? What role have these countries assigned to banks during the transition? How have they used banks in dealing with the enterprise problem? The author addresses these questions by analyzing experience in Bulgaria, Hungary, Poland, Romania, and the former Czech and Slovak Federal Republic. Most of these countries have made substantial progress in restructuring their banking systems, but few have used their banking systems to improve the allocation of credit and hence stimulate the supply response. The author finds the following. The problem is not whether banks hold nonperforming loans but how banks can avoid accumulating more nonperforming loans. The underlying problem is how to close loss-making and nonviable enterprises. The countries that have encouraged the establishment of new private banks, that have introduced regulation and supervision, and that have tried to make banks more competitive have been more successful at improving the allocation of credit and achieving more control over loss-making enterprises. Banks must focus on assessing risk - and for this, capital, private ownership, and adequate regulation are crucial. How quickly banks achieve independence in credit decisions depends on how fast new governance structures can be introduced. In this, the five countries have been less successful. The objectives of bank recapitulation should be to prevent banks from accumulating more nonperforming loans (that is, dealing with the enterprise problem) and to give them the governance structure that would prevent them from incurring new nonperforming loans. This requires introducing a system of risk and reward - by making banks comply with capital adequacy requirements, by privatizing a critical number of banks, and by introducing strong regulation and supervision. Government should see that banks provide efficient payment systems, the basis for trust in banking systems. Introducing adequate regulation and supervision has been difficult as it requires knowing what the banks'role should be. Evidence strongly supports the need to recapitalize and privatize a critical number of banks. Authorities cannot rely on banks to exert control on enterprises early in the transition. In the early stages, control over state-owned enterprises should be exercised by a semipublic institution.Banks&Banking Reform,Financial Intermediation,Financial Crisis Management&Restructuring,Municipal Financial Management,Banking Law
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