Systèmes de versants et évolution morphopédologique au Nord Togo

L'étude des niveaux cuirassés du Nord Togo permet de retrouver deux surfaces d'aplanissement : le niveau le plus élevé (500 mètres) est attribué au milieu du Tertiaire alors que la deuxième surface, à 300 mètres, a été élaborée à la fin du Tertiaire. L'organisation générale, tant morphologique que pédologique, des versants, est constante : les témoins de la surface fini-tertiaire, sur lesquels le niveau cuirassé surmonte généralement des altérites ferrallitiques, se raccordent à un glacis polygénique quaternaire très élaboré où les sols ferrugineux tropicaux dominent, le bas de versant étant soit recouvert par des colluvions, soit incisé en fonction des reprises d'érosion subactuelles. L'évolution pédologique actuelle est dominée par les phénomènes d'appauvrissement et d'individualisation des oxydes de fer, le caractère le plus original de la région étant l'importance des phénomènes d'appauvrissement interne par nappe perchée soutirante. La morphogenèse se caractérise par l'importance du ruissellement diffus. (Résumé d'auteur

The Scientific Publications of Charles Eric Dawson (1948-1990)

By the time Charles Eric Dawson died on February 11, 1993, he had produced a total of 150 published papers. His contributions represent an important chapter in the ichthyological investigations of marine fishes. His work on fishes of the Americas and on the taxonomy of pipe fishes will long be remembered as two of his most significant and outstanding achievements. Although tribute to this Canadian-American Ichthyologist and longtime Senior Ichthyologist and curator of the ichthyological research collection at the Gulf Coast Research Laboratory is presented elsewhere (Overstreet and Poss, Copeia 1993(3):921-925), it is appropriate that the extensive bibliography of one of GCRL\u27s most productive scientists is compiled and made available to other researchers who will follow in his footsteps. These publications are listed chronologically

The Scientific Publications of Charles Eric Dawson (1948-1990)

By the time Charles Eric Dawson died on February 11, 1993, he had produced a total of 150 published papers. His contributions represent an important chapter in the ichthyological investigations of marine fishes. His work on fishes of the Americas and on the taxonomy of pipe fishes will long be remembered as two of his most significant and outstanding achievements. Although tribute to this Canadian-American Ichthyologist and longtime Senior Ichthyologist and curator of the ichthyological research collection at the Gulf Coast Research Laboratory is presented elsewhere (Overstreet and Poss, Copeia 1993(3):921-925), it is appropriate that the extensive bibliography of one of GCRL\u27s most productive scientists is compiled and made available to other researchers who will follow in his footsteps. These publications are listed chronologically

Accurate 3-D Morphological Measurement Using a Structured-Light Range Sensor

A single-plane structured light range-sensor was tested to establish its usefulness in acquiring 3-D measurements of fish skulls. Twenty-one distances among 22 landmark points for each of 12 neurocrania of the scorpaenid fish Neomerinthe hemingway were taken with digital calipers, with a video-based 2-D imaging system widely used in systematic studies, and with a single-plane structured-light range sensor of inexpensive and simple design. Measures taken by 3-D sensor are highly correlated with those obtained from caliper measurement (r = 0.9995, P \u3c\u3c 0.001 ), with a precision ranging from 0.08–0.43 mm. Like caliper-based measurements, they are less strongly correlated with measurements derived from projected video-imaging. Most skulls were scanned in just over 3 minutes each. Range maps, typically establishing the (x,y,z) coordinates of more than 75,000 points per scan, can be obtained in about 40–50 CPU seconds using software running on multiple platforms. Sensor data taken from different views can be merged to build a more complete 3-D reconstruction. System design, calibration, and use are discussed. By eliminating error due to perspective effects inherent in measuring from projected video images, such sensors hold considerable promise in quantifying biological shape in 3-D for comparative and functional studies

Synthesis and structural characterization of a mimetic membrane-anchored prion protein

During pathogenesis of transmissible spongiform encephalopathies (TSEs) an abnormal form (PrPSc) of the host encoded prion protein (PrPC) accumulates in insoluble fibrils and plaques. The two forms of PrP appear to have identical covalent structures, but differ in secondary and tertiary structure. Both PrPC and PrPSc have glycosylphospatidylinositol (GPI) anchors through which the protein is tethered to cell membranes. Membrane attachment has been suggested to play a role in the conversion of PrPC to PrPSc, but the majority of in vitro studies of the function, structure, folding and stability of PrP use recombinant protein lacking the GPI anchor. In order to study the effects of membranes on the structure of PrP, we synthesized a GPI anchor mimetic (GPIm), which we have covalently coupled to a genetically engineered cysteine residue at the C-terminus of recombinant PrP. The lipid anchor places the protein at the same distance from the membrane as does the naturally occurring GPI anchor. We demonstrate that PrP coupled to GPIm (PrP-GPIm) inserts into model lipid membranes and that structural information can be obtained from this membrane-anchored PrP. We show that the structure of PrP-GPIm reconstituted in phosphatidylcholine and raft membranes resembles that of PrP, without a GPI anchor, in solution. The results provide experimental evidence in support of previous suggestions that NMR structures of soluble, anchor-free forms of PrP represent the structure of cellular, membrane-anchored PrP. The availability of a lipid-anchored construct of PrP provides a unique model to investigate the effects of different lipid environments on the structure and conversion mechanisms of PrP

Radio-Frequency Spectroscopy

Contains reports on four research projects

The Regenerative Capacity of the Zebrafish Caudal Fin Is Not Affected by Repeated Amputations

Background: The zebrafish has the capacity to regenerate many tissues and organs. The caudal fin is one of the most convenient tissues to approach experimentally due to its accessibility, simple structure and fast regeneration. In this work we investigate how the regenerative capacity is affected by recurrent fin amputations and by experimental manipulations that block regeneration. Methodology/Principal Findings: We show that consecutive repeated amputations of zebrafish caudal fin do not reduce its regeneration capacity and do not compromise any of the successive regeneration steps: wound healing, blastema formation and regenerative outgrowth. Interfering with Wnt/ß-catenin signalling using heat-shock-mediated overexpression of Dickkopf1 completely blocks fin regeneration. Notably, if these fins were re-amputated at the non-inhibitory temperature, the regenerated caudal fin reached the original length, even after several rounds of consecutive Wnt/ß-catenin signalling inhibition and re-amputation. Conclusions/Significance: We show that the caudal fin has an almost unlimited capacity to regenerate. Even after inhibition of regeneration caused by the loss of Wnt/ß-catenin signalling, a new amputation resets the regeneration capacity within the caudal fin, suggesting that blastema formation does not depend on a pool of stem/progenitor cells that require Wnt/ßcateni

Adverse events among Ontario home care clients associated with emergency room visit or hospitalization: a retrospective cohort study

Background: Home care (HC) is a critical component of the ongoing restructuring of healthcare in Canada. It impacts three dimensions of healthcare delivery: primary healthcare, chronic disease management, and aging at home strategies. The purpose of our study is to investigate a significant safety dimension of HC, the occurrence of adverse events and their related outcomes. The study reports on the incidence of HC adverse events, the magnitude of the events, the types of events that occur, and the consequences experienced by HC clients in the province of Ontario. Methods: A retrospective cohort design was used, utilizing comprehensive secondary databases available for Ontario HC clients from the years 2008 and 2009. The data were derived from the Canadian Home Care Reporting System, the Hospital Discharge Abstract Database, the National Ambulatory Care Reporting System, the Ontario Mental Health Reporting System, and the Continuing Care Reporting System. Descriptive analysis was used to identify the type and frequency of the adverse events recorded and the consequences of the events. Logistic regression analysis was used to examine the association between the events and their consequences. Results: The study found that the incident rate for adverse events for the HC clients included in the cohort was 13%. The most frequent adverse events identified in the databases were injurious falls, injuries from other than a fall, and medication-related incidents. With respect to outcomes, we determined that an injurious fall was associated with a significant increase in the odds of a client requiring long-term-care facility admission and of client death. We further determined that three types of events, delirium, sepsis, and medication-related incidents were associated directly with an increase in the odds of client death. Conclusions: Our study concludes that 13% of clients in homecare experience an adverse event annually. We also determined that an injurious fall was the most frequent of the adverse events and was associated with increased admission to long-term care or death. We recommend the use of tools that are presently available in Canada, such as the Resident Assessment Instrument and its Clinical Assessment Protocols, for assessing and mitigating the risk of an adverse event occurring.This work was supported by the Canadian Patient Safety Institute; Canadian Institutes of Health Research (CIHR) (Institutes of Health Services and Policy Research, Aging, Circulatory and Respiratory Health and Musculoskeletal Health and Arthritis); the Change Foundation; and the Canadian Health Services Research Foundation (grant number HC-10-05 Doran-Blais

The Time Structure of Hadronic Showers in highly granular Calorimeters with Tungsten and Steel Absorbers

The intrinsic time structure of hadronic showers influences the timing capability and the required integration time of hadronic calorimeters in particle physics experiments, and depends on the active medium and on the absorber of the calorimeter. With the CALICE T3B experiment, a setup of 15 small plastic scintillator tiles read out with Silicon Photomultipliers, the time structure of showers is measured on a statistical basis with high spatial and temporal resolution in sampling calorimeters with tungsten and steel absorbers. The results are compared to GEANT4 (version 9.4 patch 03) simulations with different hadronic physics models. These comparisons demonstrate the importance of using high precision treatment of low-energy neutrons for tungsten absorbers, while an overall good agreement between data and simulations for all considered models is observed for steel.Comment: 24 pages including author list, 9 figures, published in JINS