497 research outputs found
Nanopore Fabrication by Controlled Dielectric Breakdown
Nanofabrication techniques for achieving dimensional control at the nanometer
scale are generally equipment-intensive and time-consuming. The use of
energetic beams of electrons or ions has placed the fabrication of nanopores in
thin solid-state membranes within reach of some academic laboratories, yet
these tools are not accessible to many researchers and are poorly suited for
mass-production. Here we describe a fast and simple approach for fabricating a
single nanopore down to 2-nm in size with sub-nm precision, directly in
solution, by controlling dielectric breakdown at the nanoscale. The method
relies on applying a voltage across an insulating membrane to generate a high
electric field, while monitoring the induced leakage current. We show that
nanopores fabricated by this method produce clear electrical signals from
translocating DNA molecules. Considering the tremendous reduction in complexity
and cost, we envision this fabrication strategy would not only benefit
researchers from the physical and life sciences interested in gaining reliable
access to solid-state nanopores, but may provide a path towards manufacturing
of nanopore-based biotechnologies.Comment: 19 pages, 4 figures. Supplementary information contains 22 pages, 11
figures and 2 tables - A version of this manuscript was first submitted for
publication on April 23rd, 2013. It is currently under review at another
journa
Caractérisation électromyographique des lombalgies non-spécifiques chroniques de l'enfant et de l'adolescent
The majority of the worldwide population (80%) suffers from low back pain (LBP) over life. LBP becomes chronic (CLBP) in 10 to 15% of (all) adult cases yielding important functional and socio-economic adverse repercussions. The majority of LBP (85%) is classified as ânon-specificâ (NSCLBP), i.e. with an absence of any identified cause. LBP prevalence on children and adolescents is comparable to adults. Despite the low incidence of serious associated diseases, the fear of missing them increased patientâs exposure to radiation. However, an absence of significant correlation between radiology changes in the lower spine and low back pain was reported for school children. In this context, it is necessary to identify new tools, if possible non-irradiating and inexpensive, to identify specific characteristics of children and adolescents suffering from NSCLBP and thus improve the understanding of this pathology.An interesting tool, highlighted in adult population, is to evaluate surface electromyography (EMG) of low back muscles. Existing EMG phenomena were reported to discriminate adults with and without NSCLBP: reduced trunk muscle endurance, absence of flexion-relaxation phenomenon and guarding hypothesis during gait at different velocities. These EMG characteristics have not yet been confirmed for children and adolescents suffering of NSCLBP.This clinical context justifies the present doctoral work. The aim was to evaluate EMG characteristics in children and adolescents with NSCLBP in comparison with control participants. To achieve these objectives, several complementary studies were successively conducted.Taken together, the results of this doctoral work showed that the EMG characteristics frequently reported for NSCLBP in adults were absent or reduced in children and adolescent suffering from NSCLBP. These findings are inconsistent with the existing literature on adults and might affect the future therapeutic management of children and adolescents with NSCLBP, which is, to date, an imitation of the adult model. It would be interesting to confirm these results on the basis of a larger cohort and to reassess the same children and adolescents in adulthood to identify whether the EMG phenomenon, as known in NSCLBP adults, appears over time.La lombalgie (LBP) touche 80% de la population mondiale adulte et devient chronique dans 10 Ă 15% des cas. Pour la grande majoritĂ© des cas adultes (85%), aucune cause ne peut ĂȘtre clairement identifiĂ©e pour expliquer ces douleurs et lâon parle alors de lombalgie chronique « non-spĂ©cifique » (NSCLBP). Chez lâenfant et lâadolescent, la prĂ©valence de la NSCLBP est semblable Ă celle de lâadulte. MalgrĂ© la faible incidence de pathologies graves associĂ©es, la lombalgie de lâenfant et de lâadolescent implique, souvent dans sa prise en charge diagnostique, une exposition augmentĂ©e aux radiations et un stress parental important. Cependant, la prĂ©sence dâanomalies radiologiques est aussi frĂ©quente dans la population asymptomatique que dans la population avec NSCLBP. Ceci remet en question lâintĂ©rĂȘt clinique de la radiologie pour dĂ©pister une cause possible de NSCLBP. Dans ce contexte, il est nĂ©cessaire dâidentifier de nouveaux outils, si possible non-irradiants et peu coĂ»teux, pour identifier des caractĂ©ristiques spĂ©cifiques aux enfants et adolescents souffrant de NSCLBP et ainsi amĂ©liorer la comprĂ©hension de cette pathologie.Lâanalyse Ă©lectromyographique (EMG) de lâactivitĂ© des muscles paravertĂ©braux lombaires sâest avĂ©rĂ©e cliniquement pertinente dans la population adulte pour discriminer les patients souffrant de NSCLBP des participants asymptomatiques. Plusieurs paramĂštres EMG enregistrĂ©s lors de diffĂ©rentes tĂąches ont Ă©tĂ© identifiĂ©s chez lâadulte pour caractĂ©riser les participants NSCLBP. Les paramĂštres EMG des muscles lombaires les plus couramment rapportĂ©s dans la littĂ©rature sont : un temps de maintien rĂ©duit ainsi quâune fatigue musculaire accĂ©lĂ©rĂ©e pendant le test dâendurance des muscles extenseurs du tronc, la rĂ©duction ou lâabsence du phĂ©nomĂšne de flexion-relaxation (FRP) pendant la tĂąche de flexion maximale du tronc ainsi quâun pattern atypique supportant lâhypothĂšse de prĂ©caution pendant la marche Ă diffĂ©rentes vitesses. Si ces caractĂ©ristiques EMG spĂ©cifiques aux patients souffrant de NSCLBP ont Ă©tĂ© bien Ă©tablies chez lâadulte, la question est dĂ©sormais de savoir ce quâil en est chez lâenfant et lâadolescent souffrant de NSCLBP.Dans ce contexte clinique, lâobjectif de ce travail doctoral Ă©tait dâĂ©valuer les caractĂ©ristiques EMG dĂ©crites ci-dessus dans une cohorte dâenfants et dâadolescents souffrant de NSCLBP en comparaison Ă des participants asymptomatiques (CTRL). Pour y rĂ©pondre, plusieurs Ă©tudes complĂ©mentaires ont Ă©tĂ© effectuĂ©es.Dans leur ensemble, les travaux de cette thĂšse de doctorat ont montrĂ© que les phĂ©nomĂšnes EMG reportĂ©s dans une population adulte avec NSCLBP ne sont pas retrouvĂ©s dans une population pĂ©diatrique avec NSCLBP. Ces rĂ©sultats remettent en question le diagnostic et la prise en charge actuelle des enfants et adolescents souffrant de NSCLBP, qui est, Ă ce jour, calquĂ©e sur le modĂšle adulte. Des Ă©tudes supplĂ©mentaires sont cependant nĂ©cessaires pour confirmer ces rĂ©sultats sur une cohorte plus importante. Il serait aussi intĂ©ressant dâĂ©valuer une mĂȘme cohorte Ă partir de lâenfance jusquâĂ lâĂąge adulte afin dâĂ©valuer quels facteurs pourraient prĂ©dire lâapparition des phĂ©nomĂšnes rapportĂ©s dans la littĂ©rature adulte
Descreening of Field Effect in Electrically Gated Nanopores
This modeling work investigates the electrical modulation characteristics of
field-effect gated nanopores. Highly nonlinear current modulations are observed
in nanopores with non-overlapping electric double layers, including those with
pore diameters 100 times the Debye screening length. We attribute this extended
field-effect gating to a descreening effect, i.e. the counter-ions do not fully
relax to screen the gating potential due to the presence of strong ionic
transport
Parler en doy comme comme clerc dâarmes: miroitements du sujet dans le dĂ©bat poĂ©tique du XVe siĂšcle
The poetic debate as a genre is analyzed in this paper as an example of the integration of lyric dialogs into the form of first-person narrative. We try to explore the impact of this hybridization, especially in Christine de Pizanâs three love debates. The transposition of loversâ dialogs seems to transform the status of the I, as the narÂrator does not appear as a clerk whose authority is linked to knowledge, but as a character involved in a scene and whose role is also to articulate divergent discourses. First, we explore the narrativization of the jeu-parti and the pastourelle in the debates of Christine de Pizan and Guillaume de Machaut, showing that this rewriting leads to structural modifications in narration and elaborates the figure of an ambushed narrator, eager to appropriate other languages or discourses. This scenography emphasizes one of the most important issue of the debate genre, the art of writing the otherâs voice. The hybrid and polyphonic nature of the characterâs voice is in fact object of reflections in the fifteenth century, particularly in the debate over the âčRoman de la Roseâș: Christine de Pizan expresses in this framework her perception of the double speech inherent to charactersâ discourses, elaborated according to conventional representations of social and moral types, but at the same time reflecting the authorâs intentions. The knight of the âčDebat de deux amansâș is analyzed here as an example of these inner contradictions within the characterâs speech. As a consequence, the narratorâs implication in the dialog shades the debate as a whole: claiming to be outside and neutral, but appearing also as a character, the narrator seems no more to embody the authority and undermines the universality of knowledge: the debate can be considered as the expression of the limited point of view of an individualized character. The poetic love debate then reveals in the frame of first-person narrative a form of critical integration of other voices, which in fact weakens the didactic impact of the issues at stake: instance of subjectivity, the narrative I is also shaped by the lyric expression of desire and exemplifies the impossible neutrality of knowledge.The poetic debate as a genre is analyzed in this paper as an example of the integration of lyric dialogs into the form of first-person narrative. We try to explore the impact of this hybridization, especially in Christine de Pizanâs three love debates. The transposition of loversâ dialogs seems to transform the status of the I, as the narÂrator does not appear as a clerk whose authority is linked to knowledge, but as a character involved in a scene and whose role is also to articulate divergent discourses. First, we explore the narrativization of the jeu-parti and the pastourelle in the debates of Christine de Pizan and Guillaume de Machaut, showing that this rewriting leads to structural modifications in narration and elaborates the figure of an ambushed narrator, eager to appropriate other languages or discourses. This scenography emphasizes one of the most important issue of the debate genre, the art of writing the otherâs voice. The hybrid and polyphonic nature of the characterâs voice is in fact object of reflections in the fifteenth century, particularly in the debate over the âčRoman de la Roseâș: Christine de Pizan expresses in this framework her perception of the double speech inherent to charactersâ discourses, elaborated according to conventional representations of social and moral types, but at the same time reflecting the authorâs intentions. The knight of the âčDebat de deux amansâș is analyzed here as an example of these inner contradictions within the characterâs speech. As a consequence, the narratorâs implication in the dialog shades the debate as a whole: claiming to be outside and neutral, but appearing also as a character, the narrator seems no more to embody the authority and undermines the universality of knowledge: the debate can be considered as the expression of the limited point of view of an individualized character. The poetic love debate then reveals in the frame of first-person narrative a form of critical integration of other voices, which in fact weakens the didactic impact of the issues at stake: instance of subjectivity, the narrative I is also shaped by the lyric expression of desire and exemplifies the impossible neutrality of knowledge
Laëtitia Tabard, « Bien assailly, bien deffendu ». Le Genre du débat dans la littérature française de la fin du Moyen-ùge
« Câest beau debat que de deux bons : / Bien assailly, bien deffendu » : la formule de Charles dâOrlĂ©ans dit lâadmiration que suscite parmi les poĂštes le combat verbal Ă©lĂ©gamment menĂ©. Ce goĂ»t pour lâaltercation se manifeste sous de multiples formes durant tout le Moyen Ăge. Les dialogues contradictoires des rĂ©cits allĂ©goriques, le discours intĂ©rieur des personnages de roman, les conflits entre les sentiments personnifiĂ©s qui habitent les chansons des troubadours et des trouvĂšres, les tensons..
Le Livre de lâEspĂ©rance et le mouvement du dĂ©bat
Cet article Ă©tudie la critique des « debaz » dans le Livre de lâEspĂ©rance, pour montrer quâAlain Chartier ne rĂ©cuse pas ainsi, au profit dâune parole dâautoritĂ©, le principe de la discussion contradictoire qui donne sa forme Ă nombre de ses poĂšmes : au contraire, cette Ćuvre fait entendre en sourdine la contestation contre lâordre du monde, pour faire du mouvement du debat, inhĂ©rent Ă la conscience humaine, une expĂ©rience salutaire des limites de lâesprit.This paper reconsiders the criticism levelled against the âdebazâ in the Livre de lâEspĂ©rance, and argues that Alain Chartier does not reject in fact the principle of conflicting dialogue, so significant for the form of his poems: if this treatise gives way to the voice of religious authority, we can still hear a toned down protest against the world order, so that the movement of the debat, which is essential to human consciousness, represents a salutary experience of the limits of thought
De lâefficaciteÌ de visualisations indicielles ou symboliques pour la reÌgulation dâactiviteÌs collaboratives
National audienceRegulatory mechanisms are important when conducting collaborative activities. And previous research showed that providing individual or collective feedback about the ongoing collaboration can lead to better regulation. In this article, we propose to study the impact of different visual of indicators on the control process of collaborative activities. We studied two kinds of indicators : indexical indicators built into the objects being handled and symbolic indicators, added to the activity interface. We conducted a preliminary study with 32 participants. Our results show that regulation efficiency according to the indicator is neither better with indexical visualization nor with symbolic visualization, which leads us to think that a mixed use of indexical and symbolic visualizations would be more effective.Les meÌcanismes de reÌgulation de groupe sont particulieÌrement importants pour mener aÌ bien des activiteÌs collaboratives. Les dispositifs numeÌriques peuvent permettre une meilleure reÌgulation, notamment en fournissant des retours individuels ou collectifs sur la collaboration en cours. Dans cet article, nous proposons dâeÌtudier lâimpact que peuvent avoir diffeÌrentes visualisations dâindicateurs sur le processus de reÌgulation dans les activiteÌs collaboratives. Pour cela, nous avons eÌtudieÌ deux types dâindicateurs, les indicateurs indiciels qui se fondent dans les objets manipuleÌs, et les indicateurs symboliques qui sont adjoints aÌ lâinterface de lâactiviteÌ. Nous avons reÌaliseÌ une eÌtude preÌliminaire avec 32 participants. Les reÌsultats mitigeÌs tendent aÌ montrer que quâune visualisation indicielle ou symbolique nâest pas intrinseÌquement meilleure, ce qui nous laisser penser quâune utilisation mixte pourrait eÌtre plus efficace
Laëtitia Tabard, « Bien assailly, bien deffendu ». Le Genre du débat dans la littérature française de la fin du Moyen-ùge
« Câest beau debat que de deux bons : / Bien assailly, bien deffendu » : la formule de Charles dâOrlĂ©ans dit lâadmiration que suscite parmi les poĂštes le combat verbal Ă©lĂ©gamment menĂ©. Ce goĂ»t pour lâaltercation se manifeste sous de multiples formes durant tout le Moyen Ăge. Les dialogues contradictoires des rĂ©cits allĂ©goriques, le discours intĂ©rieur des personnages de roman, les conflits entre les sentiments personnifiĂ©s qui habitent les chansons des troubadours et des trouvĂšres, les tensons..
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