Structural analysis, clay mineralogy and K-Ar dating of fault gouges from Centovalli Line (Central Alps) for reconstruction of their recent activity

Between the cities of Domodossola and Locarno, the complex ``Centovalli Line'' tectonic zone of the Central Alps outlines deformation phases over a long period of time (probably starting similar to 30 Ma ago) and under variable P-T conditions. The last deformation phases developed gouge-bearing faults with a general E-W trend that crosscuts the roots of the Alpine Canavese zone and the Finero ultramafic body. Kinematic indicators show that the general motion was mainly dextral associated with back thrusting towards the S. The <2 mu m clay fractions of fault gouges from Centovalli Line consist mainly of illite, smectite and chlorite with varied illite-smectite, chlorite-smectite and chlorite-serpentine mixed-layers. Constrained with the illite crystallinity index, the thermal conditions induced by the tectonic activity show a gradual trend from anchizonal to diagenetic conditions. The <2 and <0.2 mu M clay fractions, and hydrothermal K-feldspar separates all provide K-Ar ages between 14.2 +/- 2.9 Ma and roughly 0 Ma, with major episodes at about 12,8, 6 and close to 0 Ma These ages set the recurrent tectonic activity and the associated fluid circulations between Upper Miocene and Recent. On the basis of the K-Ar ages and with a thermal gradient of 25-30 degrees C/km, the studied fault zones were located at a depth of 4-7 km. If they were active until now as observed in field, the exhumation was approximately 2.5-3.0 km for the last 12 Ma with a mean velocity of 0.4 mm/y. Comparison with available models on the recent Alpine evolution shows that the tectonic activity in the area relates to a continuum of the back-thrusting movements of the Canavese Line, and/or to several late-extensional phases of the Rhone-Simplon line. The Centovalli-Val Vigezzo zone therefore represents a major tectonic zone of the Central-Western Alps resulting from different interacting tectonic events. (C) 2011 Elsevier B.V. All rights reserved.

Tibial tunnel placement in posterior cruciate ligament reconstruction: a systematic review.

PURPOSE: Reconstruction of the posterior cruciate ligament (PCL) yields less satisfying results than anterior cruciate ligament reconstruction with respect to laxity control. Accurate tibial tunnel placement is crucial for successful PCL reconstruction using arthroscopic tibial tunnel techniques. A discrepancy between anatomical studies of the tibial PCL insertion site and surgical recommendations for tibial tunnel placement remains. The objective of this study was to identify the optimal placement of the tibial tunnel in PCL reconstruction based on clinical studies. METHODS: In a systematic review of the literature, MEDLINE, EMBASE, Cochrane Review, and Cochrane Central Register of Controlled Trials were screened for articles about PCL reconstruction from January 1990 to September 2011. Clinical trials comparing at least two PCL reconstruction techniques were extracted and independently analysed by each author. Only studies comparing different tibial tunnel placements in the retrospinal area were included. RESULTS: This systematic review found no comparative clinical trial for tibial tunnel placement in PCL reconstruction. Several anatomical, radiological, and biomechanical studies have described the tibial insertion sites of the native PCL and have led to recommendations for placement of the tibial tunnel outlet in the retrospinal area. However, surgical recommendations and the results of morphological studies are often contradictory. CONCLUSIONS: Reliable anatomical landmarks for tunnel placement are lacking. Future randomized controlled trials could compare precisely defined tibial tunnel placements in PCL reconstruction, which would require an established mapping of the retrospinal area of the tibial plateau with defined anatomical and radiological landmarks.

Micromeasurement of total and regional CO2 productions in the one-day-old chick embryo.

A conductometric micromethod combined with image analysis system has been developed allowing to determine the CO2 production within 'two-dimensional' tissues, i.e., flat and thin cell layers or epithelial sheets. The preparation was mounted into an airtight chamber separated in two compartments by a thin silicone membrane permeable to gases. The lower compartment contained the nutritive medium and the preparation. The upper compartment and a conductivity measuring capillary connected in series were perfused with a solution of Ba(OH)2. The CO2 produced by the tissue precipitated as BaCO3 and the resulting decrease of electrical conductivity was linearly related to the total CO2 production. In addition, the pattern of CO2 production was directly observable as the BaCO3 crystals formed upon the silicone membrane over the regions which produced CO2. The spatial distribution of the crystals was quantified by video image processing and the regional CO2 production evaluated with a spatial resolution of 100 microns. This new microtechnique was originally developed to study the CO2 production in the early chick blastoderm which is a disc 1-5 cells thick. At the stage of young neurula the CO2 production was found to be 235 +/- 37 nmol.h-1 (mean +/- SD; n = 10) per blastoderm and large variations of local CO2 production were detected from one region to another (from 0.6 to 6.5 nmol.h-1.mm-2). These results indicate a high metabolic and functional differentiation of cells within the blastoderm. The possible applications and improvements of such a microtechnique are discussed.

A high-resolution anatomical atlas of the transcriptome in the mouse embryo.

Ascertaining when and where genes are expressed is of crucial importance to understanding or predicting the physiological role of genes and proteins and how they interact to form the complex networks that underlie organ development and function. It is, therefore, crucial to determine on a genome-wide level, the spatio-temporal gene expression profiles at cellular resolution. This information is provided by colorimetric RNA in situ hybridization that can elucidate expression of genes in their native context and does so at cellular resolution. We generated what is to our knowledge the first genome-wide transcriptome atlas by RNA in situ hybridization of an entire mammalian organism, the developing mouse at embryonic day 14.5. This digital transcriptome atlas, the Eurexpress atlas (http://www.eurexpress.org), consists of a searchable database of annotated images that can be interactively viewed. We generated anatomy-based expression profiles for over 18,000 coding genes and over 400 microRNAs. We identified 1,002 tissue-specific genes that are a source of novel tissue-specific markers for 37 different anatomical structures. The quality and the resolution of the data revealed novel molecular domains for several developing structures, such as the telencephalon, a novel organization for the hypothalamus, and insight on the Wnt network involved in renal epithelial differentiation during kidney development. The digital transcriptome atlas is a powerful resource to determine co-expression of genes, to identify cell populations and lineages, and to identify functional associations between genes relevant to development and disease.

[Code de l'urbanisme et de l'habitation, art. 257. Décret du 19-9-55 ; arrêté du 1-10-55 et circulaires des 6 octobre et 29 novembre 1955, du Ministère de la reconstruction et du logement. Edition mise à jour au 1er mars 1956.]

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Recueil des principaux textes concernant les dommages de guerre . [Publié par le Ministère de la Reconstruction et du logement. Edition mise à jour au 1er novembre 1955.]

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Development of Craniofacial Bone Defect Reconstruction Implant Based on Fibre-Reinforced Composite with Photopolymerisable Resin Systems. Experimental studies in vitro and in vivo.

Reconstruction of defects in the craniomaxillofacial (CMF) area has mainly been based on bone grafts or metallic fixing plates and screws. Particularly in the case of large calvarial and/or craniofacial defects caused by trauma, tumours or congenital malformations, there is a need for reliable reconstruction biomaterials, because bone grafts or metallic fixing systems do not completely fulfill the criteria for the best possible reconstruction methods in these complicated cases. In this series of studies, the usability of fibre-reinforced composite (FRC) was studied as a biostable, nonmetallic alternative material for reconstructing artificially created bone defects in frontal and calvarial areas of rabbits. The experimental part of this work describes the different stages of the product development process from the first in vitro tests with resin-impregnated fibrereinforced composites to the in vivo animal studies, in which this FRC was tested as an implant material for reconstructing different size bone defects in rabbit frontal and calvarial areas. In the first in vitro study, the FRC was polymerised in contact with bone or blood in the laboratory. The polymerised FRC samples were then incubated in water, which was analysed for residual monomer content by using high performance liquid chromatography (HPLC). It was found that this in vitro polymerisation in contact with bone and blood did not markedly increase the residual monomer leaching from the FRC. In the second in vitro study, different adhesive systems were tested in fixing the implant to bone surface. This was done to find an alternative implant fixing system to screws and pins. On the basis of this study, it was found that the surface of the calvarial bone needed both mechanical and chemical treatments before the resinimpregnated FRC could be properly fixed onto it. In three animal studies performed with rabbit frontal bone defects and critical size calvarial bone defect models, biological responses to the FRC implants were evaluated. On the basis of theseevaluations, it can be concluded that the FRC, based on E-glass (electrical glass) fibres forming a porous fibre veil enables the ingrowth of connective tissues to the inner structures of the material, as well as the bone formation and mineralization inside the fibre veil. Bone formation could be enhanced by using bioactive glass granules fixed to the FRC implants. FRC-implanted bone defects healed partly; no total healing of defects was achieved. Biological responses during the follow-up time, at a maximum of 12 weeks, to resin-impregnated composite implant seemed to depend on the polymerization time of the resin matrix of the FRC. Both of the studied resin systems used in the FRC were photopolymerised and the heat-induced postpolymerisation was used additionally.

Reconstruction of networks from their betweenness centrality

In this paper we study the reconstruction of a network topology from the values of its betweenness centrality, a measure of the influence of each of its nodes in the dissemination of information over the network. We consider a simple metaheuristic, simulated annealing, as the combinatorial optimization method to generate the network from the values of the betweenness centrality. We compare the performance of this technique when reconstructing different categories of networks –random, regular, small-world, scale-free and clustered–. We show that the method allows an exact reconstruction of small networks and leads to good topological approximations in the case of networks with larger orders. The method can be used to generate a quasi-optimal topology fora communication network from a list with the values of the maximum allowable traffic for each node.

Reconstruction of the join time-delay Doppler-scale reflectivity density in the wide-band regime. A frame theory based approach

The inverse scattering problem concerning the determination of the joint time-delayDoppler-scale reflectivity density characterizing continuous target environments is addressed by recourse to the generalized frame theory. A reconstruction formula,involving the echoes of a frame of outgoing signals and its corresponding reciprocalframe, is developed. A ‘‘realistic’’ situation with respect to the transmission ofa finite number of signals is further considered. In such a case, our reconstruction formula is shown to yield the orthogonal projection of the reflectivity density onto a subspace generated by the transmitted signals.

In vitro maintenance, under slow-growth conditions, of oil palm germplasm obtained by embryo rescue

The objective of this work was to evaluate the in vitro maintenance of oil palm (Elaeis guineensis and E. oleifera) accessions under slow-growth conditions. Plants produced by embryo rescue were subject to 1/2MS culture medium supplemented with the carbohydrates sucrose, mannitol, and sorbitol at 1, 2, and 3% under 20 and 25±2ºC. After 12 months, the temperature of 20°C reduced plant growth. Sucrose is the most appropriate carbohydrate for maintaining the quality of the plants, whereas mannitol and sorbitol result in a reduced plant survival.

Robustness of Drosophila early embryo and wing imaginal disc development

Within a developing organism, cells require information on where they are in order to differentiate into the correct cell-type. Pattern formation is the process by which cells acquire and process positional cues and thus determine their fate. This can be achieved by the production and release of a diffusible signaling molecule, called a morphogen, which forms a concentration gradient: exposure to different morphogen levels leads to the activation of specific signaling pathways. Thus, in response to the morphogen gradient, cells start to express different sets of genes, forming domains characterized by a unique combination of differentially expressed genes. As a result, a pattern of cell fates and specification emerges.Though morphogens have been known for decades, it is not yet clear how these gradients form and are interpreted in order to yield highly robust patterns of gene expression. During my PhD thesis, I investigated the properties of Bicoid (Bcd) and Decapentaplegic (Dpp), two morphogens involved in the patterning of the anterior-posterior axis of Drosophila embryo and wing primordium, respectively. In particular, I have been interested in understanding how the pattern proportions are maintained across embryos of different sizes or within a growing tissue. This property is commonly referred to as scaling and is essential for yielding functional organs or organisms. In order to tackle these questions, I analysed fluorescence images showing the pattern of gene expression domains in the early embryo and wing imaginal disc. After characterizing the extent of these domains in a quantitative and systematic manner, I introduced and applied a new scaling measure in order to assess how well proportions are maintained. I found that scaling emerged as a universal property both in early embryos (at least far away from the Bcd source) and in wing imaginal discs (across different developmental stages). Since we were also interested in understanding the mechanisms underlying scaling and how it is transmitted from the morphogen to the target genes down in the signaling cascade, I also quantified scaling in mutant flies where this property could be disrupted. While scaling is largely conserved in embryos with altered bcd dosage, my modeling suggests that Bcd trapping by the nuclei as well as pre-steady state decoding of the morphogen gradient are essential to ensure precise and scaled patterning of the Bcd signaling cascade. In the wing imaginal disc, it appears that as the disc grows, the Dpp response expands and scales with the tissue size. Interestingly, scaling is not perfect at all positions in the field. The scaling of the target gene domains is best where they have a function; Spalt, for example, scales best at the position in the anterior compartment where it helps to form one of the anterior veins of the wing. Analysis of mutants for pentagone, a transcriptional target of Dpp that encodes a secreted feedback regulator of the pathway, indicates that Pentagone plays a key role in scaling the Dpp gradient activity.

Sparse image reconstruction on the sphere: implications of a new sampling theorem.

We study the impact of sampling theorems on the fidelity of sparse image reconstruction on the sphere. We discuss how a reduction in the number of samples required to represent all information content of a band-limited signal acts to improve the fidelity of sparse image reconstruction, through both the dimensionality and sparsity of signals. To demonstrate this result, we consider a simple inpainting problem on the sphere and consider images sparse in the magnitude of their gradient. We develop a framework for total variation inpainting on the sphere, including fast methods to render the inpainting problem computationally feasible at high resolution. Recently a new sampling theorem on the sphere was developed, reducing the required number of samples by a factor of two for equiangular sampling schemes. Through numerical simulations, we verify the enhanced fidelity of sparse image reconstruction due to the more efficient sampling of the sphere provided by the new sampling theorem.

The Application of 3D Reconstruction Techniques in the Analysis of Ancient Tarraco’s Urban Topography

The widespread implementation of GIS-based 3D topographical models has been a great aid in the development and testing of archaeological hypotheses. In this paper, a topographical reconstruction of the ancient city of Tarraco, the Roman capital of the Tarraconensis province, is presented. This model is based on topographical data obtained through archaeological excavations, old photographic documentation, georeferenced archive maps depicting the pre-modern city topography, modern detailed topographical maps and differential GPS measurements. The addition of the Roman urban architectural features to the model offers the possibility to test hypotheses concerning the ideological background manifested in the city shape. This is accomplished mainly through the use of 3D views from the main city accesses. These techniques ultimately demonstrate the ‘theatre-shaped’ layout of the city (to quote Vitrubius) as well as its southwest oriented architecture, whose monumental character was conceived to present a striking aspect to visitors, particularly those arriving from the sea.

Fibronectin in the area opaca of the young chick embryo. Immunofluorescence and immuno-electron-microscopic study

Distribution of fibronectin-like immunoreactivity was studied in the area opaca of the young chick embryo (stages 4-6 HH) by use of the immunofluorescence and protein A-coupled to colloidal gold techniques. Fibronectin, associated to the basement membrane, formed a fibrillar network, the pattern of which changed from the centre to the periphery of the area opaca. At the ultrastructural level, differences in fibronectin distribution were found between non-moving and moving cells. The epithelial-like cells presented fibronectin staining exclusively on their basal side. Actively migrating cells (edge and mesodermal cells) showed immunoreactive material localized around their entire surface and within the cytoplasm. The fibronectin distribution is discussed in relation to three important phenomena taking place during the early growth of the area opaca: anchorage and migration of the edge cells, modification of cell shape in relation to mechanical tension, and expansion of the area vasculosa.

Investigation of discrete imaging models and iterative image reconstruction in differential X-ray phase-contrast tomography.

Differential X-ray phase-contrast tomography (DPCT) refers to a class of promising methods for reconstructing the X-ray refractive index distribution of materials that present weak X-ray absorption contrast. The tomographic projection data in DPCT, from which an estimate of the refractive index distribution is reconstructed, correspond to one-dimensional (1D) derivatives of the two-dimensional (2D) Radon transform of the refractive index distribution. There is an important need for the development of iterative image reconstruction methods for DPCT that can yield useful images from few-view projection data, thereby mitigating the long data-acquisition times and large radiation doses associated with use of analytic reconstruction methods. In this work, we analyze the numerical and statistical properties of two classes of discrete imaging models that form the basis for iterative image reconstruction in DPCT. We also investigate the use of one of the models with a modern image reconstruction algorithm for performing few-view image reconstruction of a tissue specimen.