The optimum speed of wheel - rail's system

El concepte de velocitat òptima és un paràmetre bàsic per arribar a definir el programa d'explotació més convenient d'un servei ferroviari. Basat en l'anànisis de costos i beneficis permet donar resposta a quina ha de ser la velocitat més adequada a considerar d'acord amb un determinat entorn competencial i econòmic. Aquest concepte va ser introduït pels serveis ferroviaris francesos d'alta velocitat posant de manifest que l'objectiu no havia de ser el circular tan ràpid com fos possible sinó com comercialment fos necessari

Resonant Mode Coupling in δ\delta Scuti Stars

Delta Scuti ($\delta$ Sct) variables are intermediate mass stars that lie at the intersection of the main sequence and the instability strip on the Hertzsprung-Russel diagram. Various lines of evidence indicate that nonlinear mode interactions shape their oscillation spectra, including the particularly compelling detection of resonantly interacting mode triplets in the $\delta$ Sct star KIC 8054146. Motivated by these observations, we use the theory of three-mode coupling to study the strength and prevalence of nonlinear mode interactions in fourteen $\delta$ Sct models that span the instability strip. For each model, we calculate the frequency detunings and nonlinear coupling strengths of $\sim 10^4$ unique combinations of mode triplets. We find that all the models contain at least $\sim 100$ well-coupled triplets whose detunings and coupling strengths are consistent with the triplets identified in KIC 8054146. Our results suggest that resonant mode interactions can be significant in $\delta$ Sct stars and may explain why many exhibit rapid changes in amplitude and oscillation period.Comment: 13 pages, 8 figures. Submitted to Ap

Establishing the mangrove killifish, Kryptolebias marmoratus, as a model species for developmental biology

The mangrove killifish, Kryptolebias marmoratus, has the potential of becoming a strong model organism for a range of biological disciplines thanks to its ability to self-fertilise, a process only known to occur in invertebrate animals until its discovery. Selfing, a natural occurrence in this species, has lead to the formation of clonal lineages composed of highly homozygous individuals. The aim of this thesis was to further establish K. marmoratus in the field of developmental biology by providing an information infrastructure to help advance research on this peculiar animal and further promote its place in the pantheon of model organisms. To do so, I first set out to standardise K. marmoratus embryology by providing defined developmental stages with clear visual representations of key embryonic structures. This staging series is an essential tool that will ensure repeatability and consistency within and across different laboratories. Secondly, I examined several techniques for embryonic manipulation and for imaging that can be used in an array of experimental designs. Using these techniques I demonstrated microinjection of embryos by monitoring the yolk syncytial layer and its nuclei, and time-lapse analyses of the yolk surface during embryonic development. Finally, I applied the knowledge gained from my first two studies and examined Bmp signalling in K. marmoratus embryos and its influence on body patterning. By inhibiting this pathway, I found a new phenotype characterised by an extremely short and split body axis. These data highlighted the importance of studying known signalling pathways in unknown organisms as species-specific differences may improve our understanding of fundamental developmental processes. This thesis demonstrates that with its easily obtainable and manipulated embryos, K. marmoratus can be used for embryological research in the same light as other model organisms such as zebrafish or medaka. The rising amount of information on mangrove killifish will help further take advantage of this unique and intriguing species, and supports the use of this hermaphroditic vertebrate as a strong comparative model in developmental biology.Natural Environment Research Counci

EXAMPLE OF PALEOSEBKHA LITTORAL DEPOSITS OF SENONIAN IN THE "BASINS ZONE" OF AIT OURIR (MARRAKECH HIGH ATLAS, MOROCCO)

The comparative analysis of three cuts oriented West-East at the level of the basin of Jbel Sour, led to defining during the Santonian: A western sector of detrital coarse sediments, deposited in the context of a fluvial dynamics. Oriental sector of mainly carbonato- evaporite sedimentation, in a less deep and confined environment, subject to significant subsidence under a hot, arid climate favoring the formation of sebkha facies. These santonien deposits are organized in a regressive megasequence, surmounted by a Maastrichtian transgressive formation, corresponding, in this area, to a tidal-flats environment. This Maastrichtian serie marking the return of the epicontinental sea, under a hot, arid climate, by an Atlantic transgression encompassing the entire study area

Novel reliable and dynamic energy-aware routing protocol for large scale wireless sensor networks

Wireless sensor networks (WSN) are made up of an important number of sensors, called nodes, distributed in random way in a concerned monitoring area. All sensor nodes in the network are mounted with limited energy sources, which makes energy harvesting on top of the list of issues in WSN. A poor communication architecture can result in excessive consumption, reducing the network lifetime and throughput. Centralizing data collection and the introduction of gateways (GTs), to help cluster heads (CHs), improved WSN life time significantly. However, in vast regions, misplacement and poor distribution of GTs wastes a huge amount of energy and decreases network’s performances. In this work, we describe a reliable and dynamic with energy-awareness routing (RDEAR) protocol that provides a new GT’s election approach taking into consideration CHs density, transmission distance and energy. Applied on 20 different networks, RDEAR reduced the overall energy consumption, increased stability zone and network life time as well as other compared metrics. Our proposed approach increased network’s throughput up to 75.92% , 67.7% and 9.78% compared to the low energy adaptive clustering hierarchy (LEACH), distributed energy efficient clustering (DEEC) and static multihop routing (SMR), protocols, respectively

Origins and functions of liver myofibroblasts

AbstractMyofibroblasts combine the matrix-producing functions of fibroblasts and the contractile properties of smooth muscle cells. They are the main effectors of fibrosis in all tissues and make a major contribution to other aspects of the wound healing response, including regeneration and angiogenesis. They display the de novo expression of α-smooth muscle actin. Myofibroblasts, which are absent from the normal liver, are derived from two major sources: hepatic stellate cells (HSCs) and portal mesenchymal cells in the injured liver. Reliable markers for distinguishing between the two subpopulations at the myofibroblast stage are currently lacking, but there is evidence to suggest that both myofibroblast cell types, each exposed to a particular microenvironment (e.g. hypoxia for HSC-MFs, ductular reaction for portal mesenchymal cell-derived myofibroblasts (PMFs)), expand and exert specialist functions, in scarring and inflammation for PMFs, and in vasoregulation and hepatocellular healing for HSC-MFs. Angiogenesis is a major mechanism by which myofibroblasts contribute to the progression of fibrosis in liver disease. It has been clearly demonstrated that liver fibrosis can regress, and this process involves a deactivation of myofibroblasts, although probably not to a fully quiescent phenotype. This article is part of a Special Issue entitled: Fibrosis: Translation of basic research to human disease

A hybrid objective function with empirical stability aware to improve RPL for IoT applications

The diverse applications of the internet of things (IoT) require adaptable routing protocol able to cope with several constraints. Thus, RPL protocol was designed to meet the needs for IoT networks categorized as low power and lossy networks (LLN). RPL uses an objective function based on specific metrics for preferred parents selection through these packets are sent to root. The single routing metric issue generally doesn’t satisfy all routing performance requirements, whereas some are improved others are degraded. In that purpose, we propose a hybrid objective function with empirical stability aware (HOFESA), implemented in the network layer of the embedded operating system CONTIKI, which combines linearly three weighty metrics namely hop count, RSSI and node energy consumption. Also, To remedy to frequent preferred parents changes problems caused by taking into account more than one metric, our proposal relies on static and empirical thresholds. The designed HOFESA, evaluated under COOJA emulator against Standard-RPL and EC-OF, showed a packet delivery ratio improvement, a decrease in the power consumption, the convergence time and DIO control messages as well as it gives network stability through an adequate churn

Bmp suppression in mangrove killifish embryos causes a split in the body axis

This is the final version of the article. Available from Public Library of Science via the DOI in this record.Bone morphogenetic proteins (Bmp) are major players in the formation of the vertebrate body plan due to their crucial role in patterning of the dorsal-ventral (DV) axis. Despite the highly conserved nature of Bmp signalling in vertebrates, the consequences of changing this pathway can be species-specific. Here, we report that Bmp plays an important role in epiboly, yolk syncytial layer (YSL) movements, and anterior-posterior (AP) axis formation in embryos of the self-fertilizing mangrove killifish, Kryptolebias marmoratus. Stage and dose specific exposures of embryos to the Bmp inhibitor dorsomorphin (DM) produced three distinctive morphologies, with the most extreme condition creating the splitbody phenotype, characterised by an extremely short AP axis where the neural tube, somites, and notochord were bilaterally split. In addition, parts of caudal neural tissues were separated from the main body and formed cell islands in the posterior region of the embryo. This splitbody phenotype, which has not been reported in other animals, shows that modification of Bmp may lead to significantly different consequences during development in other vertebrate species.SM was funded by a PhD studentship from the Natural and Environmental Research Council (NERC) in the U

Occurrence of Fungi and Fungal Toxins in Fish Feed during Storage

Periods of unfavorable storing conditions can lead to changes in the quality of fish feeds, as well as the development of relevant mycotoxins. In the present study, a commercial fish feed was stored under defined conditions for four weeks. The main findings indicate that even storing fish feeds under unsuitable conditions for a short duration leads to a deterioration in quality. Mycotoxin and fungal contamination were subsequently analyzed. These investigations confirmed that different storage conditions can influence the presence of fungi and mycotoxins on fish feed. Notably, ochratoxin A (OTA) was found in samples after warm (25 °C) and humid (>60% relative humidity) treatment. This confirms the importance of this compound as a typical contaminant of fish feed and reveals how fast this mycotoxin can be formed in fish feed during storage