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951.
Smell is often regarded as an ancillary perception in primates, who seem so dominated by their sense of vision. In this paper, we will portray some aspects of the significance of olfaction to human life and speculate on what evolutionary factors contribute to keeping it alive. We then outline the functional architecture of olfactory sensory neurons and their signal transduction pathways, which are the primary detectors that render olfactory perception possible. Throughout the phylogenetic tree, olfactory neurons, at their apical tip, are either decorated with cilia or with microvilli. The significance of this dichotomy is unknown. It is generally assumed that mammalian olfactory neurons are of the ciliary type only. The existence of so-called olfactory microvillar cells in mammals, however, is well documented, but their nature remains unclear and their function orphaned. This paper discusses the possibility, that in the main olfactory epithelium of mammals ciliated and microvillar sensory cells exist concurrently. We review evidence related to this hypothesis and ask, what function olfactory microvillar cells might have and what signalling mechanisms they use. 相似文献
952.
Background
Numerous electrophysiological, ultrastructural, and immunocytochemical studies on rodent taste buds have been carried out on rat taste buds. In recent years, however, the mouse has become the species of choice for molecular and other studies on sensory transduction in taste buds. Do rat and mouse taste buds have the same cell types, sensory transduction markers and synaptic proteins? In the present study we have used antisera directed against PLCβ2, α-gustducin, serotonin (5-HT), PGP 9.5 and synaptobrevin-2 to determine the percentages of taste cells expressing these markers in taste buds in both rodent species. We also determined the numbers of taste cells in the taste buds as well as taste bud volume.Results
There are significant differences (p < 0.05) between mouse and rat taste buds in the percentages of taste cells displaying immunoreactivity for all five markers. Rat taste buds display significantly more immunoreactivity than mice for PLCβ2 (31.8% vs 19.6%), α-gustducin (18% vs 14.6%), and synaptobrevin-2 (31.2% vs 26.3%). Mice, however, have more cells that display immunoreactivity to 5-HT (15.9% vs 13.7%) and PGP 9.5 (14.3% vs 9.4%). Mouse taste buds contain an average of 85.8 taste cells vs 68.4 taste cells in rat taste buds. The average volume of a mouse taste bud (42,000 μm3) is smaller than a rat taste bud (64,200 μm3). The numerical density of taste cells in mouse circumvallate taste buds (2.1 cells/1000 μm3) is significantly higher than that in the rat (1.2 cells/1000 μm3).Conclusion
These results suggest that rats and mice differ significantly in the percentages of taste cells expressing signaling molecules. We speculate that these observed dissimilarities may reflect differences in their gustatory processing.953.
Salvatore D'Aniello George H Fisher Enza Topo Gabriele Ferrandino Jordi Garcia-Fernàndez Antimo D'Aniello 《BMC neuroscience》2007,8(1):109
Background
NMDA (N-methyl-D-aspartic acid) is a widely known agonist for a class of glutamate receptors, the NMDA type. Synthetic NMDA elicits very strong activity for the induction of hypothalamic factors and hypophyseal hormones in mammals. Moreover, endogenous NMDA has been found in rat, where it has a role in the induction of GnRH (Gonadotropin Releasing Hormone) in the hypothalamus, and of LH (Luteinizing Hormone) and PRL (Prolactin) in the pituitary gland. 相似文献954.
Felipe J. Llanes-Estrada Tim Van Cauteren Ángel P. Martín 《The European Physical Journal C - Particles and Fields》2007,51(4):945-952
We study the multiple solutions of the truncated propagator Dyson–Schwinger equation for a simple fermion theory with Yukawa
coupling to a scalar field. Upon increasing the coupling constant g, other parameters being fixed, more than one non-perturbative
solution breaking chiral symmetry becomes possible and we find these numerically. These “recurrences” appear as a mechanism
to generate different fermion generations as quanta of the same fundamental field in an interacting field theory, without
assuming any composite structure. The number of recurrences or flavors is reduced to the question of the value of the Yukawa
coupling, and it has no special profound significance in the standard model. The resulting mass function can have one or more
nodes and the measurement that potentially detects them can be thought of as a collider-based test of the virtual dispersion
relation for the charged lepton member of each family. This requires the three independent measurements of the charged lepton’s energy,
three-momentum and off-shellness. We illustrate how this can be achieved for the (more difficult) case of the tau lepton.
PACS 12.15.Ff; 11.30.Rd 相似文献
955.
Oleg Lebedev Hans Peter Nilles Stuart Raby Saúl Ramos-Sánchez Michael Ratz Patrick K.S. Vaudrevange Akın Wingerter 《Physics letters. [Part B]》2007
We explore a “fertile patch” of the heterotic landscape based on a Z6-II orbifold with SO(10) and E6 local GUT structures. We search for models allowing for the exact MSSM spectrum. Our result is that of order 100 out of a total 3×104 inequivalent models satisfy this requirement. 相似文献
956.
Perlbarg V Bellec P Anton JL Pélégrini-Issac M Doyon J Benali H 《Magnetic resonance imaging》2007,25(1):35-46
When applied to functional magnetic resonance imaging (fMRI) data, spatial independent component analysis (sICA), a data-driven technique that addresses the blind source separation problem, seems able to extract components specifically related to physiological noise and brain movements. These components should be removed from the data to achieve structured noise reduction and improve any subsequent detection and analysis of signal fluctuations related to neural activity. We propose a new automatic method called CORSICA (CORrection of Structured noise using spatial Independent Component Analysis) to identify the components related to physiological noise, using prior information on the spatial localization of the main physiological fluctuations in fMRI data. As opposed to existing spectral priors, which may be subject to aliasing effects for long-TR data sets (typically acquired with TR >1 s), such spatial priors can be applied to fMRI data, regardless of the TR of the acquisitions. By comparing the proposed automatic selection to a manual selection performed visually by a human operator, we first show that CORSICA is able to identify the noise-related components for long-TR data with a high sensitivity and a specificity of 1. On short-TR data sets, we validate that the proposed method of noise reduction allows a substantial improvement of the signal-to-noise ratio evaluated at the cardiac and respiratory frequencies, even in the gray matter, while preserving the main fluctuations related to neural activity. 相似文献
957.
A zero modes’ Fock space is constructed for the extended chiral WZNW model. It gives room to a realization of the fusion ring of representations of the restricted quantum universal enveloping
algebra at an even root of unity, and of its infinite dimensional extension by the Lusztig operators We provide a streamlined derivation of the characteristic equation for the Casimir invariant from the defining relations
of A central result is the characterization of the Grothendieck ring of both and in Theorem 3.1. The properties of the fusion ring in are related to the braiding properties of correlation functions of primary fields of the conformal current algebra model.
相似文献
958.
We exhibit a Poisson module restoring a twisted Poincaré duality between Poisson homology and cohomology for the polynomial
algebra endowed with Poisson bracket arising from a uniparametrised quantum affine space. This Poisson module is obtained as the
semiclassical limit of the dualising bimodule for Hochschild homology of the corresponding quantum affine space. As a corollary
we compute the Poisson cohomology of R, and so retrieve a result obtained by direct methods (so completely different from ours) by Monnier.
This research of the first author was supported by a Marie Curie Intra-European Fellowship within the 6th European Community
Framework Programme. The second author was supported by EPSRC Grant EP/D034167/1. 相似文献
959.
Ebrahimi-Fard Kurusch José M. Gracia-Bondía Frédéric Patras 《Letters in Mathematical Physics》2007,81(1):61-75
The word problem for an arbitrary associative Rota–Baxter algebra is solved. This leads to a noncommutative generalization
of the classical Spitzer identities. Links to other combinatorial aspects are indicated.
相似文献
960.
Scaling symmetry of -type Drinfel’d–Sokolov hierarchy is investigated. Applying similarity reduction to the hierarchy, one can obtain the Schlesinger
equation with (n + 1) regular singularities. Especially in the case of n = 3, the hierarchy contains the three-wave resonant system and the similarity reduction gives the generic case of the Painlevé
VI equation. We also discuss Weyl group symmetry of the hierarchy.
相似文献