Collège de France

About: Collège de France is a education organization based out in Paris, France. It is known for research contribution in the topics: Population & Receptor. The organization has 6541 authors who have published 11983 publications receiving 648742 citations. The organization is also known as: College de France.

Characteristics of central 5-HT receptors and their adaptive changes following intracerebral 5,7-dihydroxytryptamine administration in the rat.

Abstract: Lysed synaptosomal (P 2 ) fractions from adult rat brain were extensively washed and incubated in such a way that most bound 5-HT was eliminated. These membranes contained a high affinity ( K d = 1.6 nM) binding site for [ 3 H]5-HT that exhibited the expected properties of a specific receptor of 5-HT. In particular, known agonists and antagonists of 5-HT in the central nervous system inhibited the binding of [ 3 H]5-HT to synaptosomal membranes with IC 50 values ranging between 5 nM (metergoline) and 2.18 µM (MK-212). The slopes of logit-log competitive inhibition plots of [ 3 H]5-HT binding by various drugs including an agonist (quipazine) and several antagonists (methiothepin, mianserine) were less than 1.0 suggesting possible negative cooperativity. This did not occur with 5-HT itself since the Hill coefficient of [ 3 H]5-HT binding was not significantly different than one. Chemical lesioning of serotoninergic neurons by the intracerebral injection of 5,7-dihydroxytryptamine (5,7-HT) resulted in a significant increase in the number of high affinity binding sites for [ 3 H]5-HT in the hippocampus (+39%) but not in the striatum 18 days after the injection. This change was first detected on the 8th day after 5,7-HT treatment (+25%) when 5-HT levels in the hippocampus were decreased by 80% as compared with normal adult values. Neither the affinity nor the Hill coefficient of [ 3 H]5-HT binding, nor the characteristics of the binding sites for [ 3 H]dihydroalprenolol (a beta -noradrenergic antagonist) and [ 3 H]haloperidol (a DA antagonist) in the hippocampus and the striatum, respectively, were altered by 5,7-HT treatment. These findings are discussed in relation to the reported behavioral evidence for supersensitivity toward 5-HT agonists in 5,7-HT-treated animals.

Detection of a non‐Gaussian spot in WMAP

Abstract: An extremely cold and big spot in the Wilkinson Microwave Anisotropy Probe (WMAP) 1-yr data is analysed. Our work is a continuation of a previous paper by Vielva et al. that reported the detection of non-Gaussianity, with a method based on the spherical Mexican hat wavelet (SMHW) technique. We study the spots at different thresholds on the SMHW coefficient maps, considering six estimators, namely the number of maxima, the number of minima, the numbers of hot and cold spots, and the number of pixels of those spots. At SMHW scales around 4° (10° on the sky), the data deviate from Gaussianity. The analysis is performed on all of the sky, the Northern and Southern hemispheres, and on four regions covering all of the sky. A cold spot at (b = -57°,l = 209°) is found to be the source of this non-Gaussian signature. We compare the spots of our data with 10 000 Gaussian simulations, and conclude that only around 0.2 per cent of them present such a cold spot. Excluding this spot, the remaining map is compatible with Gaussianity, and even the excess of kurtosis in the paper by Vielva et al. is found to be due exclusively to this spot. Finally, we study whether the spot causing the observed deviation from Gaussianity could be generated by systematics or foregrounds. None of them seem to be responsible for the non-Gaussian detection.

Long bone histology of the hadrosaurid dinosaur Maiasaura peeblesorum: growth dynamics and physiology based on an ontogenetic series of skeletal elements

Abstract: Ontogenetic changes in the bone histology of Maiasaura peeblesorum are revealed by six relatively distinct but gradational growth stages: early and late nestling, early and late juvenile, sub-adult, and adult. These stages are distinguished not only by relative size but by changes in the histological patterns of bones at each stage. In general, the earliest stages are marked by spongy bone matrix with large vascular canals. Through growth, the cortical bone differentiates into fibro-lamellar tissue that tends to become more regularly layered in the outer cortex. By the sub-adult stage, lines of arrested growth (LAGs) begin to appear regularly. Resorption lines and substantial Haversian substitution in many long bones also begin to appear at this stage, and the external cortex has a lamellar-zonal structure in some bones that indicates imminent cessation of growth. Judging by the rates of apposition of similar bone tissues in living amniotes, and by the number and placement of LAGs, these patterns...

Functional MRI of Galvanic Vestibular Stimulation

Abstract: Lobel, Elie, Justus F. Kleine, Denis Le Bihan, Anne Leroy-Willig A, and Alain Berthoz. Functional MRI of galvanic vestibular stimulation. J. Neurophysiol. 80: 2699–2709, 1998. The cortical processi...

Solutions of the Two-Dimensional Hubbard Model: Benchmarks and Results from a Wide Range of Numerical Algorithms

Abstract: Numerical results for ground-state and excited-state properties (energies, double occupancies, and Matsubara-axis self-energies) of the single-orbital Hubbard model on a two-dimensional square lattice are presented, in order to provide an assessment of our ability to compute accurate results in the thermodynamic limit. Many methods are employed, including auxiliary-field quantum Monte Carlo, bare and bold-line diagrammatic Monte Carlo, method of dual fermions, density matrix embedding theory, density matrix renormalization group, dynamical cluster approximation, diffusion Monte Carlo within a fixed-node approximation, unrestricted coupled cluster theory, and multireference projected Hartree-Fock methods. Comparison of results obtained by different methods allows for the identification of uncertainties and systematic errors. The importance of extrapolation to converged thermodynamic-limit values is emphasized. Cases where agreement between different methods is obtained establish benchmark results that may be useful in the validation of new approaches and the improvement of existing methods.