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Search Results: 1 - 10 of 10711 matches for " Matthew LeComte "
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Delta activity independent of its activity as a ligand of Notch
Lee-Peng Mok, Tielin Qin, Boris Bardot, Matthew LeComte, Asal Homayouni, Francois Ahimou, Cedric Wesley
BMC Developmental Biology , 2005, DOI: 10.1186/1471-213x-5-6
Abstract: Using Drosophila cultured cells we show that the full length Delta promotes accumulation of Daughterless protein, fringe RNA, and pangolin RNA in the absence of Scabrous or Notch. Scabrous binds Delta and suppresses this activity even though it increases the level of the Delta intracellular domain. We also show that Scabrous can promote Notch receptor activity, in the absence of Delta.Delta has activity that is independent of its activity as a ligand of Notch. Scabrous suppresses this Delta activity. Scabrous also promotes Notch activity that is dependent on Delta's ligand activity. Thus, Notch, Delta, and Scabrous might function in complex combinatorial or mutually exclusive interactions during development. The data reported here will be of significant help in understanding these interactions in vivo.Notch (N) and Delta (Dl) are cell surface proteins that are required for differentiation of almost all tissues in the fruit fly Drosophila melanogaster. They are evolutionarily conserved, functioning similarly in animals from worms to humans [1,2]. The best-known instance of their function is the process of lateral inhibition that initiates differentiation of the neuronal and epidermal tissues from proneural cells that are predisposed to making the neuronal tissue. Proneural cells express high levels of the neuronal transcription co-factors from the Achaete Scute Complex (ASC) or related genes [3,4]. These factors require their partner Daughterless (Da) to activate transcription of the neurogenesis genes [5-7]. Da is expressed at low levels in all Drosophila cells [8] and up regulated in proneural cells specified to differentiate the neurons [5]. Whether or not the up regulation of Da expression is part of lateral inhibition is not clear in Drosophila. In Caenorhabditis elegans, however, the differential accumulation of the Da homolog HLH-2 is the earliest detectable difference between the cells taking up alternate fates during lateral inhibition [9]. As N and Dl are k
The Effects of Neurofeedback Training on Memory Performance in Elderly Subjects  [PDF]
Ga?l Lecomte, Jacques Juhel
Psychology (PSYCH) , 2011, DOI: 10.4236/psych.2011.28129
Abstract: Neurofeedback or electroencephalographic operant conditioning (EEG-OC) is an EEG biofeedback technique used to train individuals to control or modify their cortical activity through learned self-regulation. Initially used for treating a variety of pathologies, neurofeedback has been employed more recently to improve the physical or cognitive performance of human beings. The purpose of this study is to assess the hypothesis of the effect of neurofeedback (the ‘awakened mind’ model) on the memory performance of subjects aged over 65. 30 participants were shared equally between 3 groups: an experimental group that underwent 4 neurofeedback training sessions; a non-neurofeedback group trained at relaxation; and a ‘waiting list’ control group. Results showed that the members of the Neurofeedback group learned to increase the spectral power of the alpha frequency range as well as the alpha/thêta ratio, and that compared with the members of the two other groups, neurofeedback training resulted in a more pronounced decrease, albeit without any relation to changes in EEG activity and the level of stress and anxiety of participants undergoing such training. Yet contrary to expectations, no improvement of memory performance (differed recall of words and learning of lists of words) was observed. These mixed results, which suggest a wide range of applications, underline the need for a more systematic assessment of the potential applications of NFB training in elderly humans in order to be better able to specify the effects of the retained protocol on cognitive performance.
A dichotomy characterizing analytic digraphs of uncountable Borel chromatic number in any dimension
Dominique Lecomte
Mathematics , 2007,
Abstract: We study the extension of the Kechris-Solecki-Todorcevic dichotomy on analytic graphs to dimensions higher than 2. We prove that the extension is possible in any dimension, finite or infinite. The original proof works in the case of the finite dimension. We first prove that the natural extension does not work in the case of the infinite dimension, for the notion of continuous homomorphism used in the original theorem. Then we solve the problem in the case of the infinite dimension. Finally, we prove that the natural extension works in the case of the infinite dimension, but for the notion of Baire-measurable homomorphism.
Classes de Wadge potentielles des boréliens à coupes dénombrables
Dominique Lecomte
Mathematics , 2007,
Abstract: We give, for each non self-dual Wadge class C contained in the class of the Gdelta sets, a characterization of Borel sets which are not potentially in C, among Borel sets with countable vertical sections; to do this, we use results of partial uniformization.
On minimal non-potentially closed subsets of the plane
Dominique Lecomte
Mathematics , 2007,
Abstract: We study the Borel subsets of the plane that can be made closed by refining the Polish topology on the real line. These sets are called potentially closed. We first compare Borel subsets of the plane using products of continuous functions. We show the existence of a perfect antichain made of minimal sets among non-potentially closed sets. We apply this result to graphs, quasi-orders and partial orders. We also give a non-potentially closed set minimum for another notion of comparison. Finally, we show that we cannot have injectivity in the Kechris-Solecki-Todorcevic dichotomy about analytic graphs.
Uniformisations partielles et critères à la Hurewicz dans le plan
Dominique Lecomte
Mathematics , 2007,
Abstract: We give characterizations of the Borel sets potentially in some Wadge class, among the Borel sets with countable vertical sections of a product of two Polish spaces. To do this, we use some partial uniformization results.
Omega-powers and descriptive set theory
Dominique Lecomte
Mathematics , 2007,
Abstract: We study the sets of the infinite sentences constructible with a dictionary over a finite alphabet, from the viewpoint of descriptive set theory. Among other things, this gives some true co-analytic sets. The case where the dictionary is finite is studied and gives a natural example of a set at the level omega of the Wadge hierarchy.
Classes de Wadge potentielles et théorèmes d'uniformisation partielle
Dominique Lecomte
Mathematics , 2007,
Abstract: We want to give a construction as simple as possible of a Borel subset of a product of two Polish spaces. This introduces the notion of potential Wadge class. Among other things, we study the non-potentially closed sets, by proving Hurewicz-like results. This leads to partial uniformization theorems, on big sets, in the sense of cardinality or Baire category.
Tests à la Hurewicz dans le plan
Dominique Lecomte
Mathematics , 2007,
Abstract: We give, for some Borel sets of a product of two Polish spaces, including the Borel sets with countable sections, a Hurewicz-like characterization of those which cannot become a transfinite difference of open sets by changing the two Polish topologies.
Hurewicz-like tests for Borel subsets of the plane
Dominique Lecomte
Mathematics , 2007,
Abstract: Let xi be a non-null countable ordinal. We study the Borel subsets of the plane that can be made $\bormxi$ by refining the Polish topology on the real line. These sets are called potentially $\bormxi$. We give a Hurewicz-like test to recognize potentially $\bormxi$ sets.
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