1-octadecene monolayers on Si(111) hydrogen-terminated surfaces: effects of substrate doping

We have studied the electronic properties, in relation to their structural properties, of monolayers of 1-octadecene attached on a hydrogen-terminated (111) silicon surface. The molecules are attached using the free-radical reaction between C=C and Si-H activated by an ultraviolet illumination. We have compared the structural and electrical properties of monolayers formed on silicon substrate of different types (n-type and p-type) and different doping concentrations from low-doped (~1E14 cm-3) to highly doped (~1E19 cm-3) silicon substrates. We show that the monolayers on n-, p- and p+ silicon are densely packed and that they act as very good insulating films at a nanometer thickness with leakage currents as low as ~1E-7 A.cm-2 and high quality capacitance-voltage characteristics. The monolayers formed on n+-type silicon are more disordered and therefore exhibit larger leakage current densities (>1E-4 A.cm-2) when embedded in a silicon/monolayer/metal junction. The inferior structural and electronic properties obtained with n+-type silicon pinpoint the important role of surface potential and of the position of the surface Fermi level during the chemisorption of the organic monolayers.Comment: 33 pages, 8 figures, to be published J. Appl. Phy

Perturbations in the E-cadherin/catenin junctional complex in mouse embryos resulting in exencephaly

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Abstract Pronominal Anaphora in Three Registers of English

Identifying the expressions in a text that refer to the same entity, or coreference resolution, is an important problem in natural language processing. Abstract anaphora are distinct from other types of reference because they refer to abstract entities in discourse such as events, facts, and propositions, and their antecedents can have non-nominal phrase structure. Non-nominal antecedents are an interesting challenge in coreference resolution because the pronoun provides little information about the syntactic structure or semantics of the antecedent. A great deal of work in corpus annotation for coreference and coreference resolution has focused on newspaper text, and the goal of this study is to investigate how patterns in the use of abstract pronominal anaphora vary in three text types. I compiled a corpus of newswire text, spontaneous dialog and planned speech and annotated all instances of the pronouns ‘it’, this’, and ‘that’. I also annotated any non-nominal antecedents used with these pronouns. I compared frequencies of these pronouns, their referential functions, and characteristics of their non-nominal antecedents. I found variation in the frequencies of referential functions, the choice of pronoun and its referential function, the grammatical structure of non-nominal antecedents and the difficulty of the annotation task. The results indicate that the range of pronominal reference, pronominal anaphora and non-nominal antecedents in spoken discourse may not be retrievable from even very large collections of newswire texts

Real-time dynamics in spin-1/2 chains with adaptive time-dependent DMRG

We investigate the influence of different interaction strengths and dimerizations on the magnetization transport in antiferromagnetic spin-1/2 XXZ-chains. We focus on the real-time evolution of the inhomogeneous initial state with all spins pointing up along the z axis in the left half and down in the right half of the chain, using the adaptive time-dependent density-matrix renormalization group (adaptive t-DMRG). We find on time-scales accessible to us ballistic magnetization transport for small Sz-Sz-interaction and arbitrary dimerization, but almost no transport for stronger Sz-Sz-interaction, with a sharp crossover at Jz=1. At Jz=1 results indicate superdiffusive transport. Additionally, we perform a detailed analysis of the error made by the adaptive time-dependent DMRG using the fact that the evolution in the XX-model is known exactly. We find that the error at small times is dominated by the error made by the Trotter decomposition, whereas for longer times the DMRG truncation error becomes the most important, with a very sharp crossover at some "runaway" time.Comment: 13 pages, 20 figure

La constellation paternelle : une étude pilote en période prénatale

À partir d'une recherche où nous avions mis en évidence que certaines représentations maternelles prénatales concernant le nourrisson avaient un impact décisif sur les interactions précoces (Cupa et al., 1992), nous nous sommes demandés, en parallèle, quel était le poids, sur ces mêmes interactions, des représentations paternelles pendant la grossesse, sachant qu'à cette période les remaniements psychiques du père sont profonds (Bouchard-Godard, 1976 ; Cupa et al., 1997). Si, dans l'entrecroisement des deux champs théoriques où nous situons notre travail, à savoir celui de la psychanalyse et celui de la psychologie développementale, nous trouvons une littérature importante sur le père, peu de recherches concernent la période de la grossesse. Nous exposerons, pour cela, dans une première partie, les résultats et contributions permettant d'apprécier la portée des travaux sur le père, lors de la grossesse, et de présenter les points d'appels théoriques de nos hypothèses. La présentation de notre travail qui suit est celle d'une recherche comparative longitudinale qui s'étend du 7e mois de la grossesse jusqu'au 9e mois après la naissance. Il nous est apparu en effet qu'afin d'explorer simultanément les deux univers représentationnels parentaux et d'en observer les effets sur les interactions triadiques, ce type de méthodologie était le plus pertinent. Les résultats proposés, en dernière partie, concernent uniquement l'analyse des représentations paternelles.The paternal constellation: a pilot study in prenatal period In a research where the authors had argued that some maternal prenatal representations concerning the infant had a decisive impact on precocious interactions (Cupa et al., 1992), they have asked in parallel, what was the weight on these very same interactions of paternal representations during pregnancy, knowing that in this specific period psychic reorganization of the father are profound (Bouchard-Godard, 1976; Cupa et al., 1997). If, in the intertwining of the two theoretical fields where the authors situate their work, being that of psychoanalysis and developmental psychology, there is a an important literature on the father, results and contribution allow to appreciate the impact of studies on the father during pregnancy and present theoretical points of reference of the authors' hypotheses. The presentation of the following study is that of a comparative longitudinal research carried out from the 7th month of pregnancy to 9 months after birth. It appeared indeed to the authors that in order to explore simultaneously the two representational universes and to observe the effects on the triadic interactions, this type of methodology was the most relevant. The results proposed in the last part, only concern the analysis of paternal representations.La constelación paternal: un estudio en perioda prenatal A partir de una investigación dónde ponen en evidencia que ciertas representaciones maternales prenatales relativo al niño lactante tienen un impacto decisivo sobre las interacciones precoces (Cupa et al., 1992), los autores se preguntan, en paralelo, cual es el peso, sobre estas mismas interaciones, de las representaciones paternales durante el embarazo, sabiendo que durante esta perioda las transformaciones síquicos del padre son profundas (Bouchard-Godard, 1976; Cupa et al., 1997). Si, en el entrecruzamiento de los dos campos teóricos dónde se ubica el trabajo, a saber el de la sicoanálisis y el de la sícologia developmental, se encontró una literature importante sobre el padre, muy pocas investigaciones relativo a la perioda del embarazo se consiguieron. Se expone, por eso, en una primera parte, los resultados y contribuciones permitiendo apreciar el alcance de los trabajos sobre el padre durante el embarazo y presentar los puntos teóricos de sus hipotesís. La presentación del trabajo resulta de una investigación comparativa longitudinal la cual se extiende del septimo mes de embarazo hasta el noveno mes. Les apareció que para explorar simultáneamente los dos universos representativos parentales y de observar les efectos sobres las interaciones triadicas, este tipo de metodologia era más pertinente. Los resultados propuestos, en la última parte, se refieren unicamente al análisis de las representaciones paternales