Lensfree diffractive tomography for the imaging of 3D cell cultures

International audienceNew microscopes are needed to help realize the full potential of 3D organoid culture studies. In order to image large volume of 3D organoid cultures while preserving the ability to catch every single cell, we propose a new imaging platform based on lensfree microscopy. We have built a lensfree diffractive tomography setup performing multi-angle acquisitions of 3D organoid culture embedded in Matrigel ® and developed a dedicated 3D holographic reconstruction algorithm based on the Fourier diffraction theorem. With this new imaging platform, we have been able to reconstruct a 3D volume as large as 21.5 mm 3 of a 3D organoid culture of prostatic RWPE1 cells showing the ability of these cells to assemble in 3D intricate cellular network at the mesoscopic scale. Importantly, comparisons with 2D images show that it is possible to resolve single cells isolated from the main cellular structure with our lensfree diffractive tomography setup

Confinement-Induced Transition between Wavelike Collective Cell Migration Modes

International audienceThe structural and functional organization of biological tissues relies on the intricate interplay between chemical and mechanical signaling. Whereas the role of constant and transient mechanical perturbations is generally accepted, several studies recently highlighted the existence of longrange mechanical excitations (i.e., waves) at the supracellular level. Here, we confine epithelial cell mono-layers to quasi-one dimensional geometries, to force the establishment of tissue-level waves of well-defined wavelength and period. Numerical simulations based on a self-propelled Voronoi model reproduce the observed waves and exhibit a phase transition between a global and a multi-nodal wave, controlled by the confinement size. We conrm experimentally the existence of such a phasetransition, and show that wavelength and period are independent of the confinement length. Together, these results demonstrate the intrinsic origin of tissue oscillations, which could provide cells with a mechanism to accurately measure distances at the supracellular level

Manejo sustentable del ecosistema Salinas Grandes, Chaco Árido

Este libro es el resultado de tres años de investigación adaptativa conjuntamente con los pobladores de la región de Salinas Grandes , Provincia de Catamarca, en el marco del Proyecto GEF “Manejo Sustentable del Ecosistema Salinas Grandes, Chaco Árido”. El trabajo fue realizado por la Facultad de Ciencias Agropecuarias de la Universidad Nacional de Córdoba, en forma conjunta con el Programa Social Agropecuario, Delegación Catamarca; Administración de Parques Nacionales, Delegación Centro; Centro de Zoología Aplicada de la Universidad Nacional de Córdoba y la Red Agroforestal Chaco Argentina

the forest vegetation of the tolfa ceriti mountains northern latium central italy

The Forest Vegetation of the Tolfa-Ceriti Mountains (Northern Latium - Central Italy)The forests of the Tolfa-Ceriti mountains (Latium, central Italy) were investigated through a phytosociological approach. 249 relevés were performed and treated with multivariate analysis. 13 woodland communities were identified, of which 7 belong toQuercetalia pubescenti-petraeae, 1 toFagetalia sylvaticae, 1 toPopuletaliaand 4 toQuercetalia ilicis. The thermophilous Turkey oak-forests occurring on the trachytic hills of the Ceriti Mountains and on the flysch substrates of the Tolfa Mountains were included inRubio peregrinae-Quercetum cerridisass. nova.Quercus cerrisandFraxinus angustifoliasubsp.oxycarpawoodland communities of the footslopes have been ascribed toFraxino oxycarpae-Quercetum cerridis, while the widespread mesophilus Turkey oak forests have been ascribed toMelico-Quercetum cerridis. Cephalantero longifoliae-Quercetum cerridishas been restricted to acid and oligotrophic soils.Quercus petraeawoodlands, occurring on trachytic substrates have been described as a new association namedCarici olbiensis-Quercetum petraeaeass. nova. All these mixed oak woods have been included in the allianceCrataego laevigatae-Quercion cerridisArrigoni 1997. The nomenclatural problems concerning the prior nameTeucrio siculi-Quercion cerridisUbaldi 1988 are also discussed. The beech forests of the higher altitudes have been included inFraxino orni-Fagetum sylvaticae, while theAlnus glutinosaravine woodlands have been described as belonging to the new associationPolysticho setiferi-Alnetum glutinosae. Secondary communities ofAcer monspessulanumandAcer campestredeveloped on flysch substrates, and ofErica arboreaandArbutus unedo(Erico-Arbutetum unedonis) developed on trachytic substrates, have also been identified. Finally two types ofQuercus ilexwood have been identified:Cyclamino repandi-Quercetum ilicis, on sandstones, and the new associationArbuto unedonis-Quercetum ilicisass. nova on volcanic soils. This latter community can be considered as a coenological and geographical vicariant in central Italy of the sicilianErico-Quercetum ilicis

La liaison entre l'épargne et l'investissement dans les pays africains et malgaches d'expression française

Allier J.-P. La liaison entre l'épargne et l'investissement dans les pays africains et malgaches d'expression française. In: Etudes et conjoncture - Institut national de la statistique et des études économiques, n°2, 1963 (18ᵉ année). pp. 159-166

Contribution of piezometric measurement to knowledge and management of low water levels: examples on the chalk aquifer in the Champagne Ardennes region

This article is based on a BRGM study on piezometric indicators, threshold values of discharge and groundwater levels for the assessment of potentially-exploitable water resources of chalky watersheds. A method for estimating low water levels based on groundwater levels is presented from three examples representing chalk aquifers with different cycles: annual, combined and interannual. The first is located in Picardy and the two others in the Champagne-Ardennes region. Piezometers with annual cycles, used in these examples, are supposed to be representative of the aquifer hydro-dynamics. Except for multi-annual systems, the analysis between discharge measurements at a hydrometric station and groundwater levels measured at a piezometer representative of the main aquifer, leads to relatively precise and satisfactory relationships within a chalky context. These relationships may be useful for monitoring, validation, extension or reconstruction of the low water flow data. On the one hand, they allow definition of the piezometric levels corresponding to the different alert thresholds of river discharges. On the other hand, they clarify the proportions of low surface water flow from runoff or drainage of the aquifer. Finally, these correlations give an assessment of the minimum flow for the coming weeks. However, these correlations cannot be used to optimize the value of the exploitable water resource because it seems to be difficult to integrate the value of the effective rainfall that could occur during the draining period. Moreover, in the case of multi-annual systems, the solution is to attempt a comprehensive system modelling and, if it is satisfactory, using the simulated values to get rid of parasites or running the model for forecasting purposes

A 120nm low power asynchronous ADC

ISBN 1-59593-137-6This paper discusses the development of a new kind of low power processing chain which dynamically adapts sampling frequency to signals. Thus, the design of an Asynchronous Analog-to-Digital Converter (A-ADC) is tackled. Its principle is based on a non-uniform sampling scheme and asynchronous technology, that allow significant activity and power savings. A test chip targetting 10-bit speech applications has been fabricated using the 120nm CMOS process from STMicroelectronics. The power consumption is lower than 180µW leading to a Figure of Merit two times better than those of classical Nyquist converters recently published

Dynamics of cell and tissue growth acquired by means of extended field of view lensfree microscopy

International audienc