999 resultados para A7


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"September 1974."

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The collision (6)He+ (120)Sn has been investigated at four energies near the Coulomb barrier. A large yield of a particles has been detected, with energies around the energy of the scattered (6)He beam. The energy and angular distributions of the a particles have been analyzed and compared with breakup and neutron transfer calculations.

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The elastic scattering of (6)He on (120)Sn has been measured at four energies above the Coulomb barrier using the (6)He beam produced at the RIBRAS (Radioactive Ion Beams in Brasil) facility. The elastic angular distributions have been analyzed with the optical model and three- and four-body continuum-discretized coupled-channels calculations. The total reaction cross sections have been derived and compared with other systems of similar masses.

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The elastic-scattering angular distribution for (8)Li on (12)C has been measured at E(LAB) = 23.9 MeV with (8)Li radioactive nuclear beam produced by the Radioactive Ion Beams in Brazil facility. This angular distribution was analyzed in terms of optical-model with Woods-Saxon and double-folding Sao Paulo potential. The roles of the breakup and inelastic channels were also investigated with cluster folding and deformed potentials, respectively, through coupled-channels calculations. The angular distribution for the proton-transfer (12)C((8)Li, (9)Be)(11)B reaction was also measured at the same energy. The spectroscopic factor for the <(9)Be|(8)Li + p > bound system was obtained and compared with shell-model calculations and with other experimental values. Total reaction cross sections for the present system were also extracted from the elastic-scattering analysis. A systematic of the reduced reaction cross sections obtained from the present and published data on (6,7,8)Li isotopes on (12)C was performed as a function of energy.

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New data for the (6)He + (9)Be reaction at E(1ab) = 16.2 and 21.3 MeV have been taken and analyzed. The effect of the collective couplings to the excited states of the target has been studied by means of coupled-channels calculations, using a double-folding potential for the bare interaction between the colliding nuclei, supplemented with a phenomenological imaginary part of Woods-Saxon type. In addition, three- and four-body continuum-discretized coupled-channels calculations have been performed to investigate the effect of the projectile breakup on the elastic scattering. Both effects, the coupling to target and projectile excited states, are found to affect significantly the elastic scattering. The trivial local polarization potential extracted from the continuum-discretized coupled-channels calculations indicates that continuum couplings produce a repulsive real part and a long-range imaginary part in the projectile-target interaction.

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The activities of conantokin-G (con-G), conantokin-T (con-T), and several novel analogues have been studied using polyamine enhancement of [H-3]MK-801 binding to human glutamate-N-methyl-D-aspartate (NMDA) receptors, and their structures have been examined using CD and H-1 NMR spectroscopy. The potencies of con-G[A7], con-G, and con-T as noncompetitive inhibitors of spermine-enhanced [H-3]MK-801 binding to NMDA receptor obtained from human brain tissue are similar to those obtained using rat brain tissue. The secondary structure and activity of con-G are found to be highly sensitive to amino acid substitution and modification. NMR chemical shift data indicate that con-G, con-G[D8,D17], and con-G[A7] have similar conformations in the presence of Ca2+. This consists of a helix for residues 2-16, which is kinked in the vicinity of Gla10. This is confirmed by 3D structure calculations on con-G[A7]. Restraining this helix in a linear form (i.e., con-G[A7,E10-K13]) results in a minor reduction in potency. Incorporation of a 7-10 salt-bridge replacement (con-G[K7-E10]) prevents helix formation in aqueous solution and produces a peptide with low potency. Peptides with the Leu5-Tyr5 substitution also have low potencies (con-G[Y5,A7] and con-G[Y5,K7]) indicating that Leu5 in con-G is important for full antagonist behavior. We have also shown that the Gla-Ala7 substitution increases potency, whereas the Gla-Lys7 substitution has no effect. Con-G and con-G[K7] both exhibit selectivity between NMDA subtypes from mid-frontal and superior temporal gyri, but not between sensorimotor and mid-frontal gyri. Asn8 and/or Asn17 appear to be important for the ability of con-G to function as an inhibitor of polyamine-stimulated [3H]MK-801 binding, but not in maintaining secondary structure. The presence of Ca2+ does not increase the potencies of con-G and con-T for NMDA receptors but does stabilize the helical structures of con-G, con-G[D8,D17], and, to a lesser extent, con-G[A7]. The NMR data support the existence of at least two independent Ca2+-chelating sites in con-G, one involving Gla7 and possibly Gla3 and the other likely to involve Gla10 and/or Gla14.

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OBJECTIVE: A new nerve transfer technique using a healthy fascicle of the posterior cord for suprascapular nerve reconstruction is presented. This technique was used in a patient with posttraumatic brachial plexopathy resulting in upper trunk injury with proximal root stumps that were unavailable for grafting associated with multiple nerve dysfunction. CLINICAL PRESENTATION: A 45-year-old man sustained a right brachial plexus injury after a bicycle accident. Clinical evaluation and electromyography indicated upper trunk involvement. Trapezius muscle function and triceps strength were normal on physical examination. INTERVENTION: The patient underwent a combined supra- and infraclavicular approach to the brachial plexus. A neuroma-in-continuity of the upper trunk and fibrotic C5 and C6 roots were identified. Electrical stimulation of the phrenic and spinal accessory nerves produced no response. The suprascapular nerve was dissected from the upper trunk, transected, and rerouted to the infraclavicular fossa. A healthy fascicle of the posterior cord to the triceps muscle was transferred to the suprascapular nerve. At the time of the 1-year follow-up evaluation, arm abduction against gravity and external rotation reached 40 and 34 degrees, respectively. CONCLUSION: The posterior cord can be used as a source of donor fascicle to the suprascapular nerve after its infraclavicular relocation. This new intraplexal nerve transfer could be applied in patients with isolated injury of the upper trunk and concomitant lesion of the extraplexal nerve donors usually used for reinnervation of the suprascapular nerve.

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Insect ganglia are often composed of fused segmental units or neuromeres. We estimated the evolution of the ventral nerve cord (VNC) in higher Diptera by comparing the patterns of neuromere fusion among 33 families of the Brachycera. Variation within families is uncommon, and VNC architecture does not appear to be influenced by body shape. The outgroup pattern, seen in lower Diptera, is fusion of neuromeres belonging to thoracic segments 1 and 2 (T1 and T2), and fusion of neuromeres derived from T3 and abdominal segment 1 (A1). In the abdomen, neuromeres A7-10 are fused into the terminal abdominal ganglion (TAG). Increased neuromere fusion is a feature of the Brachycera. No brachyceran shows less fusion than the outgroups. We established six pattern elements; (1) fusion of T1 and T2, (2) fusion of T3 and A1, (3) fusion of the T1/T2 andT3/A1 ganglia, (4) increase in the number of neuromeres comprising the TAG, (5) anteriorward fusion of abdominal neuromeres, and (6) the complete fusion of thoracic and abdominal neuromeres into a synganglion. States 1 and 2 are present in the outgroup lower Diptera, and state 3 in the Xylophagomorpha, Stratiomyomorpha, Tabanomorpha and Cyclorrhapha. State 4 is a feature of all Eremoneura. State 5 is present in Cyclorrhapha only, and state 6, fusion into a synganglion, has evolved at least 4 times in the Eremoneura. Synapomorphies are provided for the Cyclorrhapha and Muscoidea, and a grouping of three basal brachyceran infraorders Xylophagomorpha, Stratiomyomorpha and Tabanomorpha. The patterns of fusion suggest that VNC architecture has evolved irreversibly, in accordance with Dollo's law.

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The present study describes the distribution and cellular morphology of catecholaminergic neurons in the CNS of two species of monotreme, the platypus (Ornithorhynchus anatinus) and the short-beaked echidna (Tachyglossus aculeatus). Tyrosine hydroxylase immunohistochemistry was used to visualize these neurons. The standard A1-A17, C1-C3 nomenclature was used for expediency, but the neuroanatomical names of the various nuclei have also been given. Monotremes exhibit catecholaminergic neurons in the diencephalon (All, A12, A13, A14, A15), midbrain (A8, A9, A10), rostral rhombencephalon (A5, A6, A7), and medulla (A1, A2, C1, C2). The subdivisions of these neurons are in general agreement with those of other mammals, and indeed other amniotes. Apart from minor differences, those being a lack of A4, A3, and C3 groups, the catecholaminergic system of monotremes is very similar to that of other mammals. Catecholaminergic neurons outside these nuclei, such as those reported for other mammals, were not numerous with occasional cells observed in the striatum. It seems unlikely that differences in the sleep phenomenology of monotremes, as compared to other mammals, can be explained by these differences. The similarity of this system across mammalian and amniote species underlines the evolutionary conservatism of the catecholaminergic system. Copyright (C) 2002 S. Karger AG, Basel.

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A s??rie tem o objetivo de divulgar dados sistematizados sobre o servi??o p??blico federal. Dessa forma, os estudos contribuem para a consolida????o do direito constitucional de acesso ?? informa????o e para a produ????o de conhecimento sobre gest??o p??blica. O folder apresenta diversas informa????es de interesse p??blico sobre os gastos relativos ?? manuten????o da estrutura funcional do Governo Federal. Cont??m 17 infogr??ficos que incluem dados sobre a configura????o das remunera????es dos servidores, a evolu????o da receita e despesa com servidores ativos, aposentados e pensionistas e a distribui????o das despesas por unidades federadas, entre outras informa????es