Lane formation by side-stepping

In this paper we study a system of nonlinear partial differential equations, which describes the evolution of two pedestrian groups moving in opposite direction. The pedestrian dynamics are driven by aversion and cohesion, i.e. the tendency to follow individuals from the own group and step aside in the case of contraflow. We start with a 2D lattice based approach, in which the transition rates reflect the described dynamics, and derive the corresponding PDE system by formally passing to the limit in the spatial and temporal discretization. We discuss the existence of special stationary solutions, which correspond to the formation of directional lanes and prove existence of global in time bounded weak solutions. The proof is based on an approximation argument and entropy inequalities. Furthermore we illustrate the behavior of the system with numerical simulations

Photoinduced electron transfer across ortho-oligo-phenylenes and novel luminophores based on earth-abundant metals

Long-range electron-transfer is of high interest for many fields, such as artificial photosynthesis and molecular electronics. Donor – bridge – Acceptor compounds, wherein photoinduced electron transfer takes place were thoroughly investigated in this regard. Especially para-phenylene systems were chosen due to their rigid, rod-like wire behaviour. Depending on the electronic coupling of the bridge, para-phenylenes reveal �-values ranging from 0.2 to 0.8 °A−1. Their ortho-connected relatives are completely unexplored until now. In chapter I of this thesis the motivation for this work and the theoretical background for electron transfer will be given. This will be followed by a few examples of electron transfers across para-phenylenes, to put the herein presented work into perspective. In chapter II photoinduced electron-transfer across an ortho-phenylene wire consisting of 2 to 6 phenyl units will be presented. A Ru(II)-photosensitiser and a triarylamine electron donor were chosen to investigate the kinetics of the charge-shift reaction. The photoinduced forward, as well as the thermal back-reaction, were explored with time resolved measurements. Due to the flexibility of the bridge and slowly interconverting conformers in solution, analysis of charge-separation remains turbid, but a coherent analysis can be made for charge-recombination. The main discovery is that ortho-phenylenes possess very low �-values for charge-transfer, with a �-value in acetonitrile of 0.04 °A−1. The mechanism for the hole transfer is coherent tunnelling and a relevant aspect seems to be the �-pathway, which is shorter for ortho-phenylenes than for para-phenylenes. Ortho-phenylenes can therefore be considered as a new class of molecular wires. Chapter III will then present the results of photoinduced long-range electron transfer through ortho-naphthalenes, which can form different atropisomers and electron transfer is studied in these systems for the first time. Photoinduced electron transfer would not be possible without photosensitisers, which allow for an enough long living excited state with enough reducing or oxidising power, that electron transfer reactions can take place. Most photosensitisers today which reach the photophysical goals for being applied, for example in photoredox catalysis or in long-range electron transfer, rely on noble metals, such as Ru(II) or Ir(III). Therefore it would be desirable, to shift from noble metals as centres to more earth abundant metals. Nickel(0) allows for an MLCT transition when the ligand orbitals are of the right energy. In chapter IV first preliminary results of a nickel(0) bis(diphenylphosphino)naphthalene complex will be presented, which were accompanied by DFT calculations. Following this approach of using more earth-abundant metals, in chapter V the possibility of titanium(IV) complexes is considered, which could possibly undergo LMCT emission transitions. Different possible approaches towards a titanium-based luminophore will be given

Sedimentary processes in the Thau Lagoon (France): From seasonal to century time scales

As a part of the MICROBENT programme, an investigation of the sedimentation framework was carried out at the water-sediment interface in the Thau Lagoon (French Mediterranean coast). Two main sites, C4 in the middle of the lagoon and C5 near oyster farms, were visited six times between December 2001 and May 2003. Interface sediments were studied using classical sedimentology parameters (radiography RX, grain size distribution) and analysis of selected radionuclides (234Th, 7Be, 210Pb, 226Ra). On a century time scale, excess 210Pb (210Pbxs) presents classical profiles with an upper mixed layer, followed by an exponential decrease of activities to undetectable levels below 20 – 30 cm. At the central site, C4, cores seem to register episodic changes in mean grain size, presenting recurrently peaks. The upper 10 cm of 210Pbxs profiles at site C5 exhibit a mixed layer associated with coarser sediments: this could be related to biological activity. Sedimentation rates derived from 210Pbxs varied from 0.15 cm y−1 at the edge of the basin, to 0.25 cm y−1 at the central site. On a seasonal time scale, 234Th and 7Be both show significant variations in activities and in penetration within the sediment. Bioturbation rates derived from both radionuclides agree well and range between 1–10 cm2 y−1 at site C4 and 1–31 cm2 y−1 at site C5. 234Th and 7Be fluxes at the water-sediment interface show too seasonal variations, more pronounced for site C5. This latter site presents especially a higher variability that is well marked with season, probably in relation with its position near oyster farms

L’intervention psycho-éducative auprès d’enfants autistes : Une expérience en psychiatrie à Lyon

Une expérience de travail « TEACCH » réalisée à Lyon, en France, auprès d'enfants autistes dans le cadre d'un intersecteur de psychiatrie infanto-juvénile est ici décrite : la proposition d'un projet éducatif individualisé part de l'évaluation des possibilités développementales de chacun des enfants; la prise en charge des enfants s'inspire des propositions faites par E. Schopler : dans un environnement structuré l'enfant est mis en situation éducative ; des alternatives à la communication verbale sont également proposées aux enfants, pour la plupart non verbaux. Un travail avec les familles est parallèlement mis en oeuvre : il consiste en un accompagnement dans la prise en charge quotidienne du handicap par les parents; une grande place est accordée à l'harmonisation des aides apportées à l'enfant dans ses différents contextes de vie. Les apports et Iimites de ce travail sont discutés : la détente de l'enfant, l'amélioration de ses capacités relationnelles et de son autonomie sont notables; la restauration d'une qualité de vie et de relation au niveau familial est nette; le déficit mental de l'enfant est de toute évidence un facteur limitant.A "TEACCH" experience conducted in Lyon, France, with autistic children within the framework of an infant-juvenile psychiatric intersectory is described here: the proposal for an invidualized educational project stems from the developmental possibilities of each child; taking children into care is inspired by Schopler's proposals: in a structured environment the child is placed in an educational setting; alternatives to verbal communication are also proposed to the children, who for the most part are non verbal. At the same time, work with families is put into place: it consists of support in the taking in charge by the parents on a daily basis of the handicap of the child: a broad place is given to the harmonization of help to the child in his different life contexts. Contribution and limits of this work are also discussed: the child's capacity to relax, the improvement of his relational capacities and his autonomy are noteworthy; restauration of quality of life and relation with famililies is clear; the child's mental deficit is obviously a limiting factor.Aqui se describe una experiencia de trabajo con nifios autistas "TEACCH" realizada en Lyon, Francia, dentro del marco de un intersectorial de siquiatria infantil-juvenil : la propuesta de un proyecto educativo individualizado parte de la cvaluaciôn de las posibilidades de desarrollo de cada nino; el seguimiento se inspira de las proposiciones hechas par E. Shopler : en un medio estructurado el nino es expuesto a una situaciôn educativa; en donde las alternativas a la comunicacion verbal son propuestas a los ninos, en su mayoria no verbales. Paralelamente se inicia un trabajo con las familias que consiste en un acompanamiento al seguimiento diario de la incapacidad, por los padres; se acuerda una gran importancia a la armonizaciôn de las ayudas que recibe el nino en los diferentes contextos de su vida. Las contribuciones y limites de este trabajo son discutidas : la relajacion del nino, el mejoramiento de sus capacidades de relaciôn y de su autonomîa son notables ; la restauration de la calidad de vida y de relaciôn a nivel familiar es clara ; la deficiencia mental del nino es evidentemente un factor limitativo

Comparison of tablet-delivered and instructor-delivered teaching on receptive identification in children with autism spectrum disorders

The purpose of our study was to compare the effectiveness of tablet- and instructor-delivered teaching (i.e., prompting and reinforcement) on the receptive identification of one-word concepts in children with autism spectrum disorders (ASDs). To this end, we embedded a multielement design within a multiple probe design to compare the effectiveness of the two instructional modalities in seven participants. Two of the seven participants showed generalization on all concepts in fewer instructional trials following instructor-delivered teaching, whereas the remaining five participants had mixed results depending on the concept. In total, the participants showed more rapid generalization with the instructor for 14 of the 19 concepts taught. Our results suggest that tablets should not systematically replace instructor-delivered prompting and reinforcement, but that they may be used to provide supplementary teaching to children with ASD

Education through fiction: acquiring opinion-forming skills in the context of genomics

This study examined the outcomes of a newly designed four-lesson science module on opinion-forming in the context of genomics in upper secondary education. The lesson plan aims to foster sixteen-year-old students’ opinion-forming skills in the context of genomics and to test the effect of the use of fiction in the module. The basic hypothesis tested in this study is whether fiction stimulates students to develop opinions with regard to socio-scientific issues. A quasi-experimental pre- and post-test design was used, involving two treatment groups and one control group. One of the experimental groups received a science module incorporating movie clips (i.e. the movie group). The other experimental group received the same science module, however, only news report clips were used (i.e. the news report group). Prior to and after the module, 266 secondary school students completed a questionnaire to test their opinion-forming skills. The results demonstrate that the science module had a significant positive effect on students’ opinion-forming skills and that the movie group improved their skills more compared to the news report group. It may be concluded that the use of fiction, to be more specific movie clips about genomics extracted from feature films, to introduce a socio-scientific issue in the classroom stimulates students to develop their opinion-forming skills

Mice Transgenic for the Human Carcinoembryonic Antigen Gene Maintain Its Spatiotemporal Expression Pattern

The tumor marker carcinoembryonic antigen (CEA) is predominantly expressed in epithelial cells along the gastrointestinal tract and in a variety of adenocarcinomas. As a basis for investigating its in vivo regulation and for establishing an animal model for tumor immunotherapy, transgenic mice were generated with a 33-kilobase cosmid clone insert containing the complete human CEA gene and flanking sequences. CEA was found in the tongue, esophagus, stomach, small intestine, cecum, colon, and trachea and at low levels in the lung, testis, and uterus of adult mice of independent transgenic strains. CEA was first detected at day 10.5 of embryonic development (embryonic day 10.5) in primary trophoblast giant cells and was found in the developing gut, urethra, trachea, lung, and nucleus pulposus of the vertebral column from embryonic day 14.5 onwards. From embryonic day 16.5 CEA was also visible in the nasal mucosa and tongue. Because this spatiotemporal expression pattern correlates well with that known for humans, it follows that the transferred genomic region contains all of the regulatory elements required for the correct expression of CEA. Furthermore, although mice apparently lack an endogenous CEA gene, the entire repertoire of transcription factors necessary for correct expression of the CEA transgene is conserved between mice and humans. After tumor induction, these immunocompetent mice will serve as a model for optimizing various forms of immunotherapy, using CEA as a target antigen

Derivation and analysis of continuum models for crossing pedestrian traffic

In this paper we study hyperbolic and parabolic nonlinear partial differential equation models, which describe the evolution of two intersecting pedestrian flows. We assume that individuals avoid collisions by sidestepping, which is encoded in the transition rates of the microscopic 2D model. We formally derive the corresponding mean-field models and prove existence of global weak solutions for the parabolic model. Moreover we discuss stability of stationary states for the corresponding one-dimensional model. Furthermore we illustrate the rich dynamics of both systems with numerical simulations

Modeling sensitivity of biodiffusion coefficient to seasonal bioturbation

Biodiffusion coefficient is the predominant parameter used to constrain biological activity in marine sediments. Bioturbation characterization is important because of the dominant role it plays on the flux determination through the sediment-water interface. Biological mixing is quantified through models of radionuclides diagenesis by both a biodiffusion coefficient (Db) and a mixed depth (L) under the basic steady-state assumption. Based on a new global compilation of radionuclide data in marine sediments and on previously published modeling results, we show that short-live radionuclides are perfectly devoted to quantify biological mixing for sediments associated with λL2/Db lower than 125, λ representing the decay constant of the radionuclide. 75 % of the234Th-derived Db, and 79 % of the 7Be-derived Db are concerned by this result. However, as transient regimes prevail within marine sediments, especially at a seasonal time scale and within the coastal and shelf environment, it is necessary to model their impacts on Db calculations. A transient model of radionuclide decay and transport is therefore used to perform extensive sensitivity tests of Db calculations in respect to seasonal mixing. Numerical tests of seasonal sensitivity indicate that 234Th and 7Be are the most sensitive tracers to seasonal biological mixing: the steady-state assumption remains valid and applicable for most of natural marine environments. However, systematic tests reveal that incorrect seasonal sensitivity of 234Th is detected for marine environments with λL2/Db lower than 10 and greater than 1000. In these cases, the apparent seasonal variations of the biological activity need to be corrected. The main parameter in selecting the appropriate radionuclide for field analyses is the dimensionless pulse, which defines the relative importance of decay time scale relative to the seasonal time scale. This pulse controls the relative extension of the domain of satisfactory sensitivity. Consequently, long-lived radionuclides (210Pb and 228Th) are not appropriate for predicting seasonal mixing, except for specific environments which display an unexpected sensitivity to seasonal mixing. These marine environments are characterized by a moderate biological mixing and a deep mixed-layer