Quantum wire with periodic serial structure

Electron wave motion in a quantum wire with periodic structure is treated by direct solution of the Schrödinger equation as a mode-matching problem. Our method is particularly useful for a wire consisting of several distinct units, where the total transfer matrix for wave propagation is just the product of those for its basic units. It is generally applicable to any linearly connected serial device, and it can be implemented on a small computer. The one-dimensional mesoscopic crystal recently considered by Ulloa, Castaño, and Kirczenow [Phys. Rev. B 41, 12 350 (1990)] is discussed with our method, and is shown to be a strictly one-dimensional problem. Electron motion in the multiple-stub T-shaped potential well considered by Sols et al. [J. Appl. Phys. 66, 3892 (1989)] is also treated. A structure combining features of both of these is investigated.

Enhanced electron-electron correlations in nanometric epitaxial SrRuO3 epitaxial films

Epitaxial and fully strained SrRuO3 thin films have been grown on SrTiO3(100). At initial stages the growth mode is three-dimensional- (3D-)like, leading to a finger-shaped structure aligned with the substrate steps and that eventually evolves into a 2D step-flow growth. We study the impact that the defect structure associated with this unique growth mode transition has on the electronic properties of the films. Detailed analysis of the transport properties of nanometric films reveals that microstructural disorder promotes a shortening of the carrier mean free path. Remarkably enough, at low temperatures, this results in a reinforcement of quantum corrections to the conductivity as predicted by recent models of disordered, strongly correlated electronic systems. This finding may provide a simple explanation for the commonly observed¿in conducting oxides-resistivity minima at low temperature. Simultaneously, the ferromagnetic transition occurring at about 140 K, becomes broader as film thickness decreases down to nanometric range. The relevance of these results for the understanding of the electronic properties of disordered electronic systems and for the technological applications of SrRuO3¿and other ferromagnetic and metallic oxides¿is stressed.

Saccamoeba lacustris, sp. nov. (Amoebozoa: Lobosea: Hartmannellidae), a new lobose amoeba, parasitized by the novel chlamydia 'Candidatus Metachlamydia lacustris' (Chlamydiae: Parachlamydiaceae).

An amoeba isolated from an aquatic biotope, identified morphologically as Saccamoeba limax, was found harbouring mutualistic rod-shaped gram-negative bacteria. During their cultivation on agar plates, a coinfection also by lysis-inducing chlamydia-like organisms was found in some subpopulations of that amoeba. .Here we provide a molecular-based identification of both the amoeba host and the two bacterial endosymbionts. Analysis of the 18S rRNA gene revealed that this strain is the sister-group to Glaeseria, for which we proposed the name Saccamoeba lacustris. The rod-shaped endosymbiont was identified as a member of Variovorax paradoxus group (Comamonadaceae, Beta-Proteobacteria). No growth on bacteriological agars was recorded, hence this symbiont might be strictly intracellular. The chlamydia-like parasite was unable to infect Acanthamoeba and other amoebae in coculture, showing high host specificity. Phylogenetic analysis based on the 16S rDNA indicated that it is a new member of the family Parachlamydiaceae (order Chlamydiales), for which we proposed the name 'Candidatus Metachlamydia lacustris'.

Computer-aided procedure for optimization of layer thickness uniformity in thermal evaporation physical vapor deposition chambers for lens coating

A computer-aided method to improve the thickness uniformity attainable when coating multiple substrates inside a thermal evaporation physical vapor deposition unit is presented. The study is developed for the classical spherical (dome-shaped) calotte and also for a plane sector reversible holder setup. This second arrangement is very useful for coating both sides of the substrate, such as antireflection multilayers on lenses. The design of static correcting shutters for both kinds of configurations is also discussed. Some results of using the method are presented as an illustration.

Evolution of a Ladinian (Middle Triassic) intraplatform basin : stratigraphy, microfacies and palaeoecology of the Meride Limestone (Monte San Giorgio, Canton Ticino, Southern Switzerland)

The Monte San Giorgio (Southern Alps, Ticino, Switzerland) is the most important locality in the world for vertebrates dating back to the Middle Triassic. For this reason it was registered in 2003 as a UNESCO World Heritage Site. One of the objectives of this doctoral thesis was to fill some of the cognitive gaps regarding the Ladinian succession, including in particular the San Giorgio Dolomite and the Meride Limestone. In order to achieve this, the entire succession, more than 600 metres thick, was measured and sampled. Biostratigraphic research based on new finds of fossil invertebrates and microfossils and on the palynological analysis of the entire section was integrated with single-zircon U-Pb dating of volcanic ash layers intercalated in the carbonate succession. This enabled a redefinition of the bio-chronostratigraphic and geochronologic framework of the succession, which encompasses a significantly shorter time interval than previously held. The Ladinian section extends from the E. curionii Ammonoid Zone (Early Fassanian) to the P. archelaus Ammonoid Zone (Early Longobardian). The age of the classic fossiliferous levels of the Meride Limestone, rich in organic matter and containing vertebrate fossils which are known all over the world, was defined in both biostratigraphic and geochronologic terms. The presumed stratigraphie significance of the pachypleurosaurid reptiles found in such levels is called into question by new finds. These fossiliferous horizons were found to correspond to the main volcanoclastic intervals of the Buchenstein Formation (Middle and Upper Pietra Verde). Thus, a correlation with the Bagolino Section (Italy) containing the GSSP for the base of the Ladinian was proposed. Bulk sedimentation rates in the studied succession average 200 m/Myr and therefore prove to be 20 times higher than those of the South-Alpine pelagic basins. These values express high carbonate productivity from the surrounding platforms on one hand, and on the other a marked subsidence of the basin. Only in the intervals consisting of laminated limestones did the sedimentation rates drop to average values of around 30 m/Myr. The distribution of organic and inorganic facies appears to be the consequence of relative variations in sea-level. The laminated and organic-matter- rich intervals of the Meride Limestone are linked to a relative sea-level drop which favoured dysoxic to anoxic bottom-water conditions, coupled with an increase in runoff, perhaps due to recurrent explosive volcanic activity. The transient development under dysoxic conditions of monospecific benthic meio-/macrofaunas was documented. Organic matter suggests a predominant origin due to benthic bacterial activity, as can be witnessed in alveolar structures typical of exopolymeric substances secreted by bacteria within microbial mats. A microbial contribution to the carbonate (peloidal) precipitation was documented. The protective effect exerted by these microbial mats is also indicated as the main taphonomic factor contributing to the excellent preservation of vertebrate fossils. A radiolarian assemblage discovered in the lower part of the section (earliest Ladinian, E. curionii Zone) suggests the transient existence of open-marine but not deep-water connections with the tethyan pelagic basins. It shows marked similarities to the faunas typical of the late Anisian, suggesting therefore a low resolution power provided by radiolarian biostratigraphy in recognizing the Anisian/Ladinian boundary. The present thesis describes a new species of conifer (Elatocladus cassinae), a new species of insect (Dasyleptus triassicus) and seven new species of radiolarians (Eptingium danieli, Eptingium neriae, Parentactinosphaera eoladinica, Sepsagon ticinensis, Sepsagon? valporinae, Novamuria wirzi and Pessagnollum? hexaspinosum). In addition, following revision of the type material of already existent taxa, four new genera of radiolarians are introduced: Bernoulliella, Eohexastylus, Ticinosphaera and Lahmosphaera.

Evolution of mRNA expression levels of autosomal and sex-linked genes in amniotes

In addition to differences in protein-coding gene sequences, changes in expression resulting from mutations in regulatory sequences have long been hypothesized to be responsible for phenotypic differences between species. However, unlike comparison of genome sequences, few studies, generally restricted to pairwise comparisons of closely related mammalian species, have assessed between-species differences at the transcriptome level. They reported that gene expression evolves at different rates in various organs and in a pattern that is overall consistent with neutral models of evolution. In the first part of my thesis, I investigated the evolution of gene expression in therian mammals (i.e.7 placental and marsupials), based on microarray data from human, mouse and the gray short-tailed opossum (Monodelphis domestica). In addition to autosomal genes, a special focus was given to the evolution of X-linked genes. The therian X chromosome was recently shown to be younger than previously thought and to harbor a specific gene content (e.g., genes involved in brain or reproductive functions) that is thought to have been shaped by specific sex-related evolutionary forces. Sex chromosomes derive from ordinary autosomes and their differentiation led to the degeneration of the Y chromosome (in mammals) or W chromosome (in birds). Consequently, X- or Z-linked genes differ in gene dose between males and females such that the heterogametic sex has half the X/Z gene dose compared to the ancestral state. To cope with this dosage imbalance, mammals have been reported to have evolved mechanisms of dosage compensation.¦In the first project, I could first show that transcriptomes evolve at different rates in different organs. Out of the five tissues I investigated, the testis is the most rapidly evolving organ at the gene expression level while the brain has the most conserved transcriptome. Second, my analyses revealed that mammalian gene expression evolution is compatible with a neutral model, where the rates of change in gene expression levels is linked to the efficiency of purifying selection in a given lineage, which, in turn, is determined by the long-term effective population size in that lineage. Thus, the rate of DNA sequence evolution, which could be expected to determine the rate of regulatory sequence change, does not seem to be a major determinant of the rate of gene expression evolution. Thus, most gene expression changes seem to be (slightly) deleterious. Finally, X-linked genes seem to have experienced elevated rates of gene expression change during the early stage of X evolution. To further investigate the evolution of mammalian gene expression, we generated an extensive RNA-Seq gene expression dataset for nine mammalian species and a bird. The analyses of this dataset confirmed the patterns previously observed with microarrays and helped to significantly deepen our view on gene expression evolution.¦In a specific project based on these data, I sought to assess in detail patterns of evolution of dosage compensation in amniotes. My analyses revealed the absence of male to female dosage compensation in monotremes and its presence in marsupials and, in addition, confirmed patterns previously described for placental mammals and birds. I then assessed the global level of expression of X/Z chromosomes and contrasted this with its ancestral gene expression levels estimated from orthologous autosomal genes in species with non-homologous sex chromosomes. This analysis revealed a lack of up-regulation for placental mammals, the level of expression of X-linked genes being proportional to gene dose. Interestingly, the ancestral gene expression level was at least partially restored in marsupials as well as in the heterogametic sex of monotremes and birds. Finally, I investigated alternative mechanisms of dosage compensation and found that gene duplication did not seem to be a widespread mechanism to restore the ancestral gene dose. However, I could show that placental mammals have preferentially down-regulated autosomal genes interacting with X-linked genes which underwent gene expression decrease, and thus identified a novel alternative mechanism of dosage compensation.

Detection of scalar gravitational waves with a hollow spherical antenna

We study the response and cross sections for the absorption of GW energy generated in a Jordan-Brans-Dicke theory by a resonant mass detector shaped as a hollow sphere. As a source of the GW we take a binary system in the Newtonian approximation. For masses of the stars of the order of the solar mass, the emitted GW sweeps a range of frequencies which include the first resonant mode of the detector.

Tonotopic mapping of human auditory cortex.

Since the early days of functional magnetic resonance imaging (fMRI), retinotopic mapping emerged as a powerful and widely-accepted tool, allowing the identification of individual visual cortical fields and furthering the study of visual processing. In contrast, tonotopic mapping in auditory cortex proved more challenging primarily because of the smaller size of auditory cortical fields. The spatial resolution capabilities of fMRI have since advanced, and recent reports from our labs and several others demonstrate the reliability of tonotopic mapping in human auditory cortex. Here we review the wide range of stimulus procedures and analysis methods that have been used to successfully map tonotopy in human auditory cortex. We point out that recent studies provide a remarkably consistent view of human tonotopic organisation, although the interpretation of the maps continues to vary. In particular, there remains controversy over the exact orientation of the primary gradients with respect to Heschl's gyrus, which leads to different predictions about the location of human A1, R, and surrounding fields. We discuss the development of this debate and argue that literature is converging towards an interpretation that core fields A1 and R fold across the rostral and caudal banks of Heschl's gyrus, with tonotopic gradients laid out in a distinctive V-shaped manner. This suggests an organisation that is largely homologous with non-human primates. This article is part of a Special Issue entitled Human Auditory Neuroimaging.

Persistent hyperglycemia at 24-48 h in acute hyperglycemic stroke patients is not associated with a worse functional outcome.

BACKGROUND: Recently, it was shown that the relation between admission glucose and functional outcome after ischemic stroke is described by a J-shaped curve, with a glucose range of 3.7-7.3 mmol/l associated with a favorable outcome. We tested the hypothesis that persistence of hyperglycemia above this threshold at 24-48 h after stroke onset impairs 3-month functional outcome. METHODS: We analyzed all patients with glucose >7.3 mmol/l on admission from the Acute STroke Registry and Analysis of Lausanne (ASTRAL). Patients were divided into two groups according to their subacute glucose level at 24-48 h after last well-being time (group 1: ≤7.3 mmol/l, group 2: >7.3 mmol/l). A favorable functional outcome was defined as a modified Rankin Score (mRS) ≤2 at 3 months. A multiple logistic regression analysis of multiple demographic, clinical, laboratory and neuroimaging covariates was performed to assess predictors of an unfavorable outcome. RESULTS: A total of 1,984 patients with ischemic stroke were admitted between January 1, 2003 and October 20, 2009, within 24 h after last well-being time. In the 421 patients (21.2%) with admission glucose >7.3 mmol/l, the proportion of patients with a favorable outcome was not statistically significantly different between the two groups (59.2 vs. 48.7%, respectively). In multiple logistic regression analysis, unfavorable outcome was significantly associated with age (odds ratio, OR: 1.06, 95% confidence interval, 95% CI: 1.03-1.08 for every 10-year increase), National Institute of Health Stroke Score, NIHSS score, on admission (OR: 1.16, 95% CI: 1.11-1.21), prehospital mRS (OR: 12.63, 95% CI: 2.61-61.10 for patients with score >0), antidiabetic drug usage (OR: 0.36, 95% CI: 0.15-0.86) and glucose on admission (OR: 1.16, 95% CI: 1.02-1.31 for every 1 mmol/l increase). No association was found between persistent hyperglycemia at 24-28 h and outcome in either diabetics or nondiabetics. CONCLUSIONS: In ischemic stroke patients with acute hyperglycemia, persistent hyperglycemia (>7.3 mmol/l) at 24-48 h after stroke onset is not associated with a worse functional outcome at 3 months whether the patient was previously diabetic or not.

The Moroccan political partisan landscape : a polarized microcosm?

Using an original investigative protocol and a data base of 4,127 national delegates from ten Moroccan political organizations, surveyed between 2008 and 2012, this article examines the characteristics of party members in Morocco. Initial results indicate that the field of Moroccan political parties is a small world dominated by city dwellers, mature men, and the most highly educated, wealthiest individuals. However, far from being isolated from ordinary citizens, there are social dynamics at work. While it cannot be reduced to a segmented clientele, it is, nonetheless, shaped by an ideal-typical opposition between parties of notables and parties of activists.

Ankle joint pressure in pes cavovarus after lateralizing calcaneal osteotomies

BACKGROUND: Tendon transfers and calcaneal osteotomies are commonly used to treat symptoms related to medial ankle arthrosis in fixed pes cavovarus. However, the relative effect of these osteotomies in terms of lateralizing the ground contact point of the hindfoot and redistributing ankle joint contact stresses are unknown. MATERIALS AND METHODS: Pes cavovarus with fixed hindfoot varus was simulated in eight cadaver specimens. The effect of three types of calcaneal osteotomies on the migration of the center of force and tibiotalar peak pressure at 300 N axial static load (half-body weight) were recorded using pressure sensors. RESULTS: A significant lateral shift of the center of force was observed: 4.9 mm for the laterally closing Z-shaped osteotomy with additional lateralization of the tuberosity, 3.4 mm for the lateral sliding osteotomy of the calcaneal tuberosity, and 2.7 mm for the laterally closing Z-shaped osteotomy (all p < 0.001). A significant peak pressure reduction was recorded: -0.53 MPa for the Z-shaped osteotomy with lateralization, -0.58 MPa for the lateral sliding osteotomy of the calcaneal tuberosity, and -0.41 MPa for the Z-shaped osteotomy (all p < 0.01). CONCLUSION: This cadaver study supports the hypothesis that lateralizing calcaneal osteotomies substantially help to normalize ankle contact stresses in pes cavovarus.

High-density collagen gel tubes as a matrix for primary human bladder smooth muscle cells.

Tissue-engineered grafts for the urinary tract are being investigated for the potential treatment of several urologic diseases. These grafts, predominantly tubular-shaped, usually require in vitro culture prior to implantation to allow cell engraftment on initially cell-free scaffolds. We have developed a method to produce tubular-shaped collagen scaffolds based on plastic compression. Our approach produces a ready cell-seeded graft that does not need further in vitro culture prior to implantation. The tubular collagen scaffolds were in particular investigated for their structural, mechanical and biological properties. The resulting construct showed an especially high collagen density, and was characterized by favorable mechanical properties assessed by axial extension and radial dilation. Young modulus in particular was greater than non-compressed collagen tubes. Seeding densities affected proliferation rate of primary human bladder smooth muscle cells. An optimal seeding density of 10(6) cells per construct resulted in a 25-fold increase in Alamar blue-based fluorescence after 2 wk in culture. These high-density collagen gel tubes, ready seeded with smooth muscle cells could be further seeded with urothelial cells, drastically shortening the production time of graft for urinary tract regeneration.

L'essence relationnelle. Fonctionnement neurobiologique et relations humaines

Dans une perspective phénoménologique, le corps, les fonctions vitales, le mouvement déterminent un échange constant entre le sujet et le monde, entre soi et l'autre. La neurobiologie, de son côté, s'intéresse aux transformations biologiques liées à ces expériences, mais sa méthode est fort différente. Les auteurs proposent une réflexion sur la manière dont les découvertes de la neurobiologie interviennent pour mieux "comprendre" la dimension de la rencontre. La relation intersubjective est façonnée non seulement par les structures du fonctionnement mental, par le vécu du sujet, mais encore par la "danse" des postures et le mouvement des corps ; elle est enfin portée par le milieu culturel et social, par la nature de l'environnement. La construction des liens entre le patient et le thérapeute permet à chacun d'eux de cheminer vers un accomplissement de sa propre existence. In a phenomenological perspective, the body, the vital functions, the movements determine a constant exchange between the subject and the world, between self and the others. The neurobiology on its part, is interested in the biological transformations connected to these experiences but its method is quite different. The authors suggest to consider how the neurobiological discoveries help to get a better understanding of the dimension of the encounter. The intersubjective relationship is not only shaped by the structures of the mental functioning, by the subject's experiences, but also by the « dance » of the postures and movements of the body; it is nonetheless influenced by the cultural and social environment, as well as by the type of environment. The build-up of relationships between the therapist and the patient allows both of them to find a way to fulfillment of their own existence.

Dynamics of driven three-dimensional thin films: from hdrophilic to superhydrophobic substrates

We study the forced displacement of a thin film of fluid in contact with vertical and inclined substrates of different wetting properties, that range from hydrophilic to hydrophobic, using the lattice-Boltzmann method. We study the stability and pattern formation of the contact line in the hydrophilic and superhydrophobic regimes, which correspond to wedge-shaped and nose-shaped fronts, respectively. We find that contact lines are considerably more stable for hydrophilic substrates and small inclination angles. The qualitative behavior of the front in the linear regime remains independent of the wetting properties of the substrate as a single dispersion relation describes the stability of both wedges and noses. Nonlinear patterns show a clear dependence on wetting properties and substrate inclination angle. The effect is quantified in terms of the pattern growth rate, which vanishes for the sawtooth pattern and is finite for the finger pattern. Sawtooth shaped patterns are observed for hydrophilic substrates and low inclination angles, while finger-shaped patterns arise for hydrophobic substrates and large inclination angles. Finger dynamics show a transient in which neighboring fingers interact, followed by a steady state where each finger grows independently.

Odorant Receptor (Or) genes: polymorphism and divergence in the D. melanogaster and D. pseudoobscura Lineages

Background: In insects, like in most invertebrates, olfaction is the principal sensory modality, which provides animals with essential information for survival and reproduction. Odorant receptors are involved in this response, mediating interactions between an individual and its environment, as well as between individuals of the same or different species. The adaptive importance of odorant receptors renders them good candidates for having their variation shaped by natural selection. Methodology/Principal Findings: We analyzed nucleotide variation in a subset of eight Or genes located on the 3L chromosomal arm of Drosophila melanogaster in a derived population of this species and also in a population of Drosophila pseudoobscura. Some heterogeneity in the silent polymorphism to divergence ratio was detected in the D. melanogaster/D. simulans comparison, with a single gene (Or67b) contributing ~37% to the test statistic. However, no other signals of a very recent selective event were detected at this gene. In contrast, at the speciation timescale, the MK test uncovered the footprint of positive selection driving the evolution of two of the encoded proteins in both D. melanogaster ¿OR65c and OR67a ¿and D. pseudoobscura ¿OR65b1 and OR67c. Conclusions: The powerful polymorphism/divergence approach provided evidence for adaptive evolution at a rather high proportion of the Or genes studied after relatively recent speciation events. It did not provide, however, clear evidence for very recent selective events in either D. melanogaster or D. pseudoobscura.