Morphogenèse des barrages de travertin de Coal River Springs, sud-est du Territoire du Yukon

L'étude de travertins, situés sur la rive gauche de la Coal River (SE du Yukon), permet de mieux comprendre la genèse de ces dépôts par leur description morphologique, soutenue d'observations hydrologiques et microfaciologiques. L'analyse morphologique révèle que les barrages de travertin sont des phytohermes, à croissance discontinue attribuable aux variations de débit. Une forme nouvelle appelée « encorbellement inverse » est décrite et correspond à une croissance en eau calme. L'analyse microscopique identifie : 1 ) un faciès algaire de type Phormidium/Schizothrix qu'on trouve sur des supports ligneux et des formes en vase, 2) un faciès en glomérule d'origine probablement bactérienne, observé sur la face amont de grands barrages, et 3) un faciès bryophytique qui est le plus fréquent et qui apparaît au sommet des barrages, c'est-à-dire dans les zones de croissance verticale. Les mousses les plus fréquentes sont Brachytecium sp., Bryum sp., Cratoneuron sp., et Gymnostonum recurvirostrum (Hedw.). Les phytohermes sont situés dans le cadre stratigraphique de l'Holocène, après l'encaissement de la Coal River dans ses alluvions. Ils se construisent selon le modèle suivant : leur croissance verticale ainsi que l'épaississement de leur face aval se font surtout par l'encroûtement des mousses et l'épaississement de leur face amont se réalise davantage par l'intermédiaire des faciès cyanobactériens.This study examines the travertine deposits exposed along the left bank of the Coal River located in southeast Yukon. The main purpose of this project is to gain a better understanding of the genesis of these deposits through their morphological descriptions, which include observations of inherent hydrological and microfacies characteristics. The travertine dams are phytoherms characterized by discontinuous forms. This discontinuous nature is attributed to variations in river discharge. A new form named "inversed corbelling" is identified and corresponds to a growth development in a low energy water. Microscopic analyses distinguish: 1) a Phormidium/ Schizothrix algal faciès, observed on pieces of wood or vase shaped substrates, 2) a glomerulitic fades of supposed bacterial origin, observed on the upstream face of dams, and most commonly, 3) a bryophytic facies observed on dam summits, where vertical growth forms prevail. The most common mosses observed are Brachytecium sp., Bryum sp., Cratoneuron sp. and Gymnostonum recurvirostrum (Hedw.). The phytoherms are placed within the Holocene stratigraphie framework, resulting from the incision of the Coal River into its alluvial deposit. A growth model for phytoherms is proposed. Their vertical growth and the thickening of the downstream face is made especially by encrusting of mosses, and the thickening of their upstream face mainly corresponds to cyano-bacterian fades.Die Untersuchung der Kalksinter auf dem linken Ufer des Coal River (Sudost-Yukon) fuhrt zu einem besseren Verstândnis der Genèse dieser Ablagerungen mittels ihrer morphologischen Beschreibung, gestùtzt auf Beobachtungen der Hydrologie und der Mikrofazies. Die morphologische Analyse ergibt, daR die Kalksinterdàmme Phytohermes sind mit unstetigem Wachstum aufgrund der Variationen der Wasserfuhrung. Eine neue Form, genannt "umgekehrtes Gesims", wird be schrieben; sie entspricht dem Wachstum bei ruhigem Wasser. Die mikroskopische Analyse identifiziert: 1)eine Algen-Fazies vom Typus Phormidium/Schizothrix, die man auf holzigen Stutzen und vasenformigen Unterlagen findet, 2) eine Knàuel-Fazies, môglicherweise bakteriellen Ursprungs, die auf dem Stirnhang oberhalb der groRen Dàmme zu sehen ist, und 3) eine bryophytische Fazies, die am hâufigsten auftritt und auf der Spitze der Dàmme ers-cheint, d.h. in den Bereichen vertikalen Wachstums. Die hàufigsten Moose sind Brachytecium sp., Bryum sp., Cratoneuron sp., und Gymnostonum recurvirostrum (Hedw.). Die Phytohermes befinden sich im stratigraphischen Rahmen des Holozàn, nachdem der Coal River sich in seinen Alluvionen eingesenkt hatte. Sie bilden sich nach folgendem Modell: ihr vertikales Wachstum sowie die Verdickung ihrer stromabwàrts gerichteten Seite geschieht vor allem durch Verkrustung der Moose, und die Verdickung ihrer stromaufwàrts gerichteten Seite wird mehr mittels der zyanobakteriellen Fazies realisiert

Somatic mosaicism by a de novo MLH1 mutation as a cause of Lynch syndrome

Background: Lynch syndrome (LS) is caused by germline mismatch repair (MMR) gene mutations. De novo MMR gene mutations are rare, and somatic mosaicism in LS is thought to be infrequent. We describe the first case of somatic mosaicism by a de novo MLH1 mutation for a patient diagnosed with a rectosigmoid adenocarcinoma at age 31. Methods: Twelve years after initial colorectal cancer diagnosis, tumor tissue of the patient was tested with sensitive next generation sequencing (NGS) analysis for the presence of somatic MMR mutations. Results: In tumor tissue, an inactivating MLH1 mutation (c.518_519del; p.(Tyr173Trpfs*18)) was detected, which was also present at low level in the blood of the patient. In both parents, as well as the patient's sisters, the mutation was not present. Conclusion: We show that low‐level mosaicism can be detected by using high‐coverage targeted NGS panels on constitutional and/or tumor DNA. This report illustrates that by using sensitive sequencing techniques, more cases of genetic diseases driven by mosaic mutations may be identified, with important clinical consequences for patients and family members

Microdomains of the C-type lectin DC-SIGN are portals for virus entry into dendritic cells

The C-type lectin dendritic cell (DC)–specific intercellular adhesion molecule grabbing non-integrin (DC-SIGN; CD209) facilitates binding and internalization of several viruses, including HIV-1, on DCs, but the underlying mechanism for being such an efficient phagocytic pathogen-recognition receptor is poorly understood. By high resolution electron microscopy, we demonstrate a direct relation between DC-SIGN function as viral receptor and its microlocalization on the plasma membrane. During development of human monocyte-derived DCs, DC-SIGN becomes organized in well-defined microdomains, with an average diameter of 200 nm. Biochemical experiments and confocal microscopy indicate that DC-SIGN microdomains reside within lipid rafts. Finally, we show that the organization of DC-SIGN in microdomains on the plasma membrane is important for binding and internalization of virus particles, suggesting that these multimolecular assemblies of DC-SIGN act as a docking site for pathogens like HIV-1 to invade the host

Testing Multiple Coordination Constraints with a Novel Bimanual Visuomotor Task

The acquisition of a new bimanual skill depends on several motor coordination constraints. To date, coordination constraints have often been tested relatively independently of one another, particularly with respect to isofrequency and multifrequency rhythms. Here, we used a new paradigm to test the interaction of multiple coordination constraints. Coordination constraints that were tested included temporal complexity, directionality, muscle grouping, and hand dominance. Twenty-two healthy young adults performed a bimanual dial rotation task that required left and right hand coordination to track a moving target on a computer monitor. Two groups were compared, either with or without four days of practice with augmented visual feedback. Four directional patterns were tested such that both hands moved either rightward (clockwise), leftward (counterclockwise), inward or outward relative to each other. Seven frequency ratios (3∶1, 2∶1, 3∶2, 1∶1, 2∶3. 1∶2, 1∶3) between the left and right hand were introduced. As expected, isofrequency patterns (1∶1) were performed more successfully than multifrequency patterns (non 1∶1). In addition, performance was more accurate when participants were required to move faster with the dominant right hand (1∶3, 1∶2 and 2∶3) than with the non-dominant left hand (3∶1, 2∶1, 3∶2). Interestingly, performance deteriorated as the relative angular velocity between the two hands increased, regardless of whether the required frequency ratio was an integer or non-integer. This contrasted with previous finger tapping research where the integer ratios generally led to less error than the non-integer ratios. We suggest that this is due to the different movement topologies that are required of each paradigm. Overall, we found that this visuomotor task was useful for testing the interaction of multiple coordination constraints as well as the release from these constraints with practice in the presence of augmented visual feedback

Tracing employment in business functions. A sectoral and occupational approach

Economic globalisation and the increased pressure on firms to outsource or relocate activities, are often perceived as primarily resulting in job losses. This perspective takes no account of the positive employment effects entailed by these developments, both in terms of new companies and of job creation in existing companies. Recently, different attempts have been made to estimate the impact of economic globalisation on job losses and job gains. The methods applied to this end differ widely, and are still in the process of development. Building on global value chain theory, this paper presents an alternative method to estimate employment effects of economic restructuring. The authors argue that, for the analysis of the structure and development of global value chains, traditional concepts and units of observation, such as ‘the enterprise’ or ‘the sector’, are inadequate, and they propose the business function as a more appropriate unit of analysis. A method is developed to identify business functions by crosstabulating sectors and occupations, and estimations of employment in several business functions are made, using data of the European Labour Force Survey. Evidence is found of a shift of business functions from sectors in which they are ‘peripheral’ to the production process, towards sectors in which they constitute the core activity.status: publishe

Jobcreatie en -destructie bij Vlaamse werkgevers. Originele cijfers op basis van een verbeterde methodologie

In samenwerking met de RSZ werkte het HIVA een methodologie uit die voor het eerst een betrouwbaar beeld geeft over jobcreatie en -destructie bij Belgische werkgevers. De methode laat tevens toe het aantal startende en stoppende werkgevers nauwkeurig in kaart te brengen. Op basis van deze methode werden dynamische kernindicatoren samengesteld voor Vlaamse werkgevers in de periode 2003-2007. Deze working paper vat de Vlaamse resultaten samen. De voornaamste conclusies zijn de volgende: - Achter de traditionele netto-statistieken, die doorgaans zeer geleidelijke evoluties weerspiegelen, gaat een enorme turbulentie op de arbeidsmarkt schuil. In de onderzochte periode gingen er elk jaar iets meer dan 100 000 jobs verloren bij krimpende ondernemingen en bij werkgevers die hun activiteiten stopzetten. Dit jobverlies werd ruimschoots goedgemaakt door groeiende en startende ondernemingen die jaarlijks zo’n 130 000 bijkomende jobs creëerden. - Jobcreatie en –destructie gebeurt gelijktijdig in alle delen van de economie, zowel in groeiende als krimpende sectoren. Zowel in de industrie als in de diensten verdwijnen jaarlijks 5 tot 6 van de 100 bestaande jobs. Het grote verschil tussen beide hoofdsectoren is dat er in de diensten een zeer krachtige jobcreatie tegenover staat, terwijl in de meeste industriële sectoren de banencreatie onvoldoende is om het jobverlies te compenseren. - Een hoge arbeidsmarktturbulentie wijst niet noodzakelijk op een sector in moeilijkheden. Integendeel, in de periode 2003 tot 2007 waren de sectoren met de hoogste turbulentie degene met de sterkste netto-groei van de werkgelegenheid. De conclusies voor Vlaanderen liggen zeer sterk in de lijn van die van internationaal onderzoek naar jobcreatie en -destructie en benadrukken onder meer dat een beleid gericht op het ondersteunen van werknemers bij hun transitie van de ene job naar de andere vertrekt van een grote en reële behoefte.KEROSINE working papernrpages: 21status: publishe

Employee flows to improve measures of job creation and destruction and of firm dynamics. The case of Belgium

This paper presents a method for improved estimation of measures of firm dynamics and job creation and destruction. In keeping with a novel approach recently developed in the Scandinavian countries and the U.S, we use employee flow information to re-establish broken links between records of the same firm, and to identify relationships between firms in case of mergers, take-overs, split-offs, and other forms of restructuring. The study is based on a linked employer-employee data set covering all private employment in Belgium. The employee flow approach results in a substantial quality improvement of the measures discussed. In the period of observation, we find that 35 to 50 per cent of total entries and exits of firms with at least 10 employees does not coincide with the real opening or closing of a firm. After correcting for these spurious events, job creation and destruction levels are substantially revised downwards. Besides affecting average levels, correcting for employee flows also strongly reduces annual variation in estimated measures, especially at the sectoral level.status: publishe