Giraud O.,University Of Toulouse Ups |
Giraud O.,French National Center for Scientific Research |
Giraud O.,University Paris - Sud |
Thas K.,Ghent University
Reviews of Modern Physics | Year: 2010
In a celebrated paper "Can one hear the shape of a drum?" M. Kac [Am. Math. Monthly 73, 1 (1966)]10.2307/2313748 asked his famous question about the existence of nonisometric billiards having the same spectrum of the Laplacian. This question was eventually answered positively in 1992 by the construction of noncongruent planar isospectral pairs. This review highlights mathematical and physical aspects of isospectrality. © 2010 The American Physical Society.
Aretz M.,University Of Toulouse Ups |
Aretz M.,French National Center for Scientific Research
Palaontologische Zeitschrift | Year: 2010
The Viséan succession of the Jerada Massif contains a relatively diverse rugose coral fauna, which comprises 12 genera. Only two of these (Siphonodendron and Lithostrotion) are reported to include more than one species. Most taxa show distinctive facies dependencies. Small solitary corals are found in shaly environments of the Oued Es-Sassi Formation. On the northern flank a coral patch reef formed on an oolitic shoal in the Koudiat Es-Senn Formation. Its core mainly consists of Lithostrotion vorticale colonies, whereas in its surroundings literally hundreds of specimens of Siphonophyllia samsonensis occur. Associated with these dominant taxa occur colonial and further large solitary taxa (Palaeosmilia, Dibunophyllum). Tizraia and Pareynia are restricted to microbial-dominated buildup facies. Their presence might be strongly controlled by the development of this buildup type, because further occurrences in Algeria, Morocco, and Belgium are all in the same facies. The coral fauna at Jerada is a typical Late Viséan assemblage for the Western European Province. The Eastern Moroccan Meseta may be an important pathway within the province for the connection between the Central Saharan basins and NW Europe. The biostratigraphic ages of the coral fauna partly contradict ages based on carbonate microfossils; the coral ages are slightly older and typical Brigantian coral taxa are absent. © 2009 Springer-Verlag.
Gillot J.,University Of Toulouse Ups |
Lepoutre S.,University Of Toulouse Ups |
Gauguet A.,University Of Toulouse Ups |
Buchner M.,University Of Toulouse Ups |
Vigue J.,University Of Toulouse Ups
Physical Review Letters | Year: 2013
In this Letter, we report a measurement of the He-McKellar-Wilkens (HMW) topological phase by atom interferometry. The experiment is done with our lithium atom interferometer, and in order to suppress the stray effects present in our first experiment, we use optical pumping of the Li7 atoms in their F=2, mF=+2 (or -2) ground state sublevel. In these conditions, the measured phase shift is the sum of the HMW phase and of the Aharonov-Casher phase, which are separated due to their different mF dependence. The HMW phase has been measured for different lithium beam velocities and the results are in very good agreement with a phase independent of the atom velocity, as expected for a topological phase. © 2013 American Physical Society.
Hoareau-Aveilla C.,University Of Toulouse Ups |
Fayet-Lebaron E.,University Of Toulouse Ups |
Jady B.E.,University Of Toulouse Ups |
Henras A.K.,University Of Toulouse Ups |
And 2 more authors.
Nucleic Acids Research | Year: 2012
Yeast snR30 is an essential box H/ACA small nucleolar RNA (snoRNA) that promotes 18S rRNA processing through forming transient base-pairing interactions with the newly synthesized 35S pre-rRNA. By using a novel tandem RNA affinity selection approach, followed by coimmunoprecipitation and in vivo cross-linking experiments, we demonstrate that in addition to the four H/ACA core proteins, Cbf5p, Nhp2p, Nop10p and Gar1p, a fraction of snR30 specifically associates with the Utp23p and Kri1p nucleolar proteins. Depletion of Utp23p and Kri1p has no effect on the accumulation and recruitment of snR30 to the nascent pre-ribosomes. However, in the absence of Utp23p, the majority of snR30 accumulates in large pre-ribosomal particles. The retained snR30 is not base-paired with the 35S pre-rRNA, indicating that its aberrant tethering to nascent preribosomes is likely mediated by pre-ribosomal protein(s). Thus, Utp23p may promote conformational changes of the pre-ribosome, essential for snR30 release. Neither Utp23p nor Kri1p is required for recruitment of snR30 to the nascent pre-ribosome. On the contrary, depletion of snR30 prevents proper incorporation of both Utp23p and Kri1p into the 90S pre-ribosome containing the 35S pre-rRNA, indicating that snR30 plays a central role in the assembly of functionally active small subunit processome. © 2011 The Author(s).
Gattobigio G.L.,French National Center for Scientific Research |
Gattobigio G.L.,Kastler-Brossel Laboratory |
Couvert A.,Kastler-Brossel Laboratory |
Georgeot B.,University Of Toulouse Ups |
And 2 more authors.
Physical Review Letters | Year: 2011
We study an experimental setup in which a quantum probe, provided by a quasimonomode guided atom laser, interacts with a static localized attractive potential whose characteristic parameters are tunable. In this system, classical mechanics predicts a transition from regular to chaotic behavior as a result of the coupling between the different degrees of freedom. Our experimental results display a clear signature of this transition. On the basis of extensive numerical simulations, we discuss the quantum versus classical physics predictions in this context. This system opens new possibilities for investigating quantum scattering, provides a new testing ground for classical and quantum chaos, and enables us to revisit the quantum-classical correspondence. © 2011 American Physical Society.
O'Donohue M.-F.,University Of Toulouse Ups |
Choesmel V.,University Of Toulouse Ups |
Faubladier M.,University Of Toulouse Ups |
Fichant G.,University Of Toulouse Ups |
Gleizes P.-E.,University Of Toulouse Ups
Journal of Cell Biology | Year: 2010
Our knowledge of the functions of metazoan ribosomal proteins in ribosome synthesis remains fragmentary. Using siRNAs, we show that knockdown of 31 of the 32 ribosomal proteins of the human 40S subunit (ribosomal protein of the small subunit [RPS]) strongly affects pre-ribosomal RNA (rRNA) processing, which often correlates with nucleolar chromatin disorganization. 16 RPSs are strictly required for initiating processing of the sequences flanking the 18S rRNA in the pre-rRNA except at the metazoan-specific early cleavage site. The remaining 16 proteins are necessary for progression of the nuclear and cytoplasmic maturation steps and for nuclear export. Distribution of these two subsets of RPSs in the 40S subunit structure argues for a tight dependence of pre-rRNA processing initiation on the folding of both the body and the head of the forming subunit. Interestingly, the functional dichotomy of RPS proteins reported in this study is correlated with the mutation frequency of RPS genes in Diamond-Blackfan anemia. © 2010 O'Donohue et al.
Sapede D.,University Of Toulouse Ups |
Sapede D.,French National Center for Scientific Research |
Cau E.,University Of Toulouse Ups |
Cau E.,French National Center for Scientific Research
Current Topics in Developmental Biology | Year: 2013
The pineal gland is a small neuroendocrine organ whose main and most conserved function is the nighttime secretion of melatonin. In lower vertebrates, the pineal gland is directly photosensitive. In contrast, in higher vertebrates, the direct photosensitivity of the pineal gland had been lost. Rather, the action of this gland as a relay between environmental light conditions and body functions involves reception of light information by the retina. In parallel to this sensory regression, the pineal gland (and its accessory organs) appears to have lost several functions in relation to light and temperature, which are important in lower vertebrate species. In humans, the functions of the pineal gland overlap with the functions of melatonin. They are extremely widespread and include general effects both on cell protection and on more precise functions, such as sleep and immunity. Recently, the role of melatonin has received a considerable amount of attention due to increased cancer risk in shift workers and the discovery that patients suffering from neurodegenerative diseases, autism, or depression exhibit abnormal melatonin rhythms. © 2013 Elsevier Inc.
Braun D.,University Of Toulouse Ups |
Braun D.,French National Center for Scientific Research |
Martin J.,University Of Toulouse Ups |
Martin J.,French National Center for Scientific Research |
Martin J.,University of Liège
Nature Communications | Year: 2011
Quantum-enhanced measurements use quantum mechanical effects to enhance the sensitivity of the measurement of classical quantities, such as the length of an optical cavity. The major goal is to beat the standard quantum limit (SQL), that is, an uncertainty of order, where N is the number of quantum resources (for example, the number of photons or atoms used), and to achieve a scaling 1/N, known as the Heisenberg limit. So far very few experiments have demonstrated an improvement over the SQL. The required quantum states are generally highly entangled, difficult to produce, and very prone to decoherence. Here, we show that Heisenberg-limited measurements can be achieved without the use of entangled states by coupling the quantum resources to a common environment that can be measured at least in part. The method is robust under decoherence, and in fact the parameter dependence of collective decoherence itself can be used to reach a 1/N scaling. © 2011 Macmillan Publishers Limited. All rights reserved.
Demery V.,University Of Toulouse Ups |
Dean D.S.,University Of Toulouse Ups
European Physical Journal E | Year: 2010
We study the drag force on uniformly moving inclusions which interact linearly with dynamical free field theories commonly used to study soft condensed matter systems. Drag forces are shown to be nonlinear functions of the inclusion velocity and depend strongly on the field dynamics. The general results obtained can be used to explain drag forces in Ising systems and also predict the existence of drag forces on proteins in membranes due to couplings to various physical parameters of the membrane such as composition, phase and height fluctuations. © 2010 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.
Giurfa M.,University Of Toulouse Ups |
Giurfa M.,French National Center for Scientific Research
Wiley Interdisciplinary Reviews: Cognitive Science | Year: 2015
Insects possess small brains but exhibit sophisticated behavioral performances. Recent works have reported the existence of unsuspected cognitive capabilities in various insect species, which go beyond the traditional studied framework of simple associative learning. In this study, I focus on capabilities such as attention, social learning, individual recognition, concept learning, and metacognition, and discuss their presence and mechanistic bases in insects. I analyze whether these behaviors can be explained on the basis of elemental associative learning or, on the contrary, require higher-order explanations. In doing this, I highlight experimental challenges and suggest future directions for investigating the neurobiology of higher-order learning in insects, with the goal of uncovering l architectures underlying cognitive processing. © 2015 John Wiley & Sons, Ltd.