Development of numerical algorithms for practical computation of nonlinear normal modes

When resorting to numerical algorithms, we show that nonlinear normal mode (NNM) computation is possible with limited implementation effort, which paves the way to a practical method for determining the NNMs of nonlinear mechanical systems. The proposed method relies on two main techniques, namely a shooting procedure and a method for the continuation of NNM motions. In addition, sensitivity analysis is used to reduce the computational burden of the algorithm. A simplified discrete model of a nonlinear bladed disk is considered to demonstrate the developments

Downscaling long term socio-economic scenarios at city scale: A case study on Paris

International audienceThe NEDUM-2D model is used to downscale four global socioeconomic scenarios at city scale and simulate the evolution of the Paris urban area between 1900 and 2100. It is based on a dynamic extension of the classical urban economic theory, to explain the spatial distribution of land and real estate values, dwelling surfaces, population density and buildings heights and density. A validation over the 1900-2010 period shows that the model reproduces available data and captures the main determinants of city shape evolution. From four global scenarios and additional local inputs, 32 local scenarios are created and analyzed. Main drivers of urban sprawl and climate and flood vulnerability appear to be local demographic growth and local policies; global factors, such as energy and transport prices, even including possible peak-oil and carbon taxes, have only a limited influence on them. Conversely, transport-related greenhouse gases emissions are mainly driven by global factors, namely vehicle efficiency changes, not by land use. As a consequence, very strict urban policies — including reconstruction — would become necessary to control emissions from urban transportation if technologies reveal unable to do so. These scenarios are a useful input for the design and assessment of mitigation and adaptation policies at local scale

Modélisation de l’effet d’une taxe sur la construction : le Versement pour Sous-Densité

National audienceLe Versement pour Sous Densité est une mesure innovante qui a fait son entrée dans la loi française depuis mi-2012 et qui vise à limiter l’étalement urbain en taxant les nouvelles constructions qui n’atteignent pas un Seuil minimal de densité. Ce papier, à travers l’utilisation d’un modèle transportusage des sols (NEDUM 2D), quantifie les impacts potentiels de cette politique sur l’Ile-de-France et examine les conditions qui lui permettraient de gagner en efficacité tout en limitant les coûts sociaux de sa mise en œuvre. Les résultats de cette étude montrent que si cet outil est correctement utilisé, il peut contribuer à limiter l’étalement urbain tout en augmentant les surfaces construites et donc en diminuant le niveau des prix immobiliers et des loyers. De façon surprenante, il s’agit donc d’une taxe sur la construction qui a pour résultat un accroissement des surfaces des logements. Cependant la mise en œuvre de cette politique est compliquée puisque le choix du Seuil minimal de densité en conditionne largement l’efficacité. Si celui-ci est trop bas le versement peut avoir des impacts contre-productifs comme une accélération de l’étalement urbain. De plus, en fonction de l’objectif privilégié (limitation de l’étalement urbain, accès aux transports en commun, …), le choix du seuil optimal variera

Viticulture and Adaptation to Climate Change

International audienceThe aim of this article is to lay out a series of issues of current concern to researchers in the social sciences, regarding the impact of climate change on the vine and wine sector. The challenge lies in evaluating the cost of transition from one system to another through an integration of the direct and indirect effects of climate change. This adaptation, whether reactive or anticipatory, combines technical and organisational innovations with localisation strategies and institutional changes. Such actions could either try to maintain the existing situation as much as possible or could try to bifurcate towards deep changes, entailing very different costs. Given the multitude of uncertainties at play, not to mention the necessity for continuous adaptation to an ever-changing climate, these costs are hard to quantify. This article will illustrate two sets of measures for wine cultivation adaptation: 'no regrets' measures, which offer immediate benefits, and 'reversible and flexible' measures, which limit the inertia of wine-cultivating systems. In spite of the challenges, what stands out is the evident re-enforcement resulting from the collaboration between researchers and political and economic actors. In the field of wine cultivation, these collaborations can follow two paths: the study of the diversity of existing wine-growing systems and genetic resources or the possibility of more radical technological and social experimentation

Utilisation des outils cohésifs comme indice de sensibilité au registre : une étude développementale

Cette étude explore l’utilisation de la subordination non fléchie comme moyen de cohésion syntaxique dans des textes écrits et oraux produits par des enfants et des adultes. Le choix de cette structure particulière comme objet d’étude a été motivé par le fait qu’elle est réputée être acquise tardivement, et qu’elle est associée à des variétés formelles du français. Les résultats révèlent que la subordination non fléchie considérée comme indice de différenciation entre français parlé et français écrit n’est pas effective avant l’âge adulte. L’ordre de passation s’avère, chez les enfants, être un facteur beaucoup plus décisif dans l’utilisation de ce trait : chez les enfants, les textes produits dans l’ordre écrit puis oral manifestent un taux d’utilisation de subordination non fléchie significativement plus élevé, quel que soit le mode de production (oral ou écrit). Ces résultats suggèrent que l’étude du développement de la syntaxe chez l’enfant ne peut ignorer à quel point les performances peuvent varier en fonction du contexte de production, ni ignorer le développement de la connaissance de l’enfant sur l’adaptation de son langage au contexte.This study investigates the use of non-finite subordination as a means of syntactic cohesion in spoken and written texts collected from French-speaking children and adults. This particular structure was selected because it is a late acquisition and is more frequent in formal varieties of French. Results reveal that differentiation between spoken and written French, measured by the use of non-finite subordination, is stable only in adult subjects. Children’s production of non-finite subordination is influenced by the order of production. Those children who produced written texts before spoken texts show a significantly higher rate in the use of non-finite subordination in both their written and their spoken texts. We conclude that the study of children’s developing syntax should take seriously into account how performance varies as a function of the production context and of children’s increasing knowledge of register appropriateness

Systematizing and upscaling urban climate change mitigation

The question of what cities can contribute to mitigation and adapting to climate change is gaining traction among researchers and policy makers alike. However, while the field is rich with case studies, methods that provide rich data across municipalities and potentially at global scale remain underdeveloped, and comparative insights remain scarce. Here we summarize contributions to the focus issue on 'Systematizing and Upscaling Urban Climate Solutions', also drawing from presentations given at an accompanying conference in 2018. We highlight four core areas for systematizing and upscaling urban climate mitigation solutions. First, with more and better (big) data and associated machine learning methods, there is increasing potential to compare types of cities and leverage collective understanding. Second, while urban climate assessments have mostly emphasized urban planning, demand-side action as related to both behavioral change and modified social practices relevant to urban space deserve more academic attention and integration across a diverse set of social sciences. Third, climate mitigation would be intangible as a single objective at the urban scale, and measures and solutions that coordinate mitigation coherently with adaptation and broader sustainable development goals require explicit conceptualization and systematization. Forth, all insights should come together to develop governance frameworks that translate scientific exercises into concrete, realistic and organized action plans on the ground, for all cities

RETRATO SIN IDENTIFICAR [Material gráfico]

Copia digital. Madrid : Ministerio de Educación, Cultura y Deporte, 201

Time-Course of Changes in the Myonuclear Domain During Denervation in Young-Adult and Old Rat Gastrocnemius Muscle

If myonuclear loss initiates muscle wasting, it should precede the loss of muscle mass. As aging affects muscle plasticity, the time-course of muscle atrophy during disuse may differ between young and old animals. To investigate this, gastrocnemius muscles of 5- and 25-month-old rats were exposed to 1, 2, or 4 weeks of denervation, whereas the contralateral gastrocnemius muscles served as controls. Muscle fibers of each type responded similarly to 4 weeks of denervation. For both ages most of the atrophy (36%; P < 0.001) occurred in the first 2 weeks. In young-adult muscles, the myonuclear number remained constant, but in old muscles it decreased to below control level after 4 weeks of denervation (P < 0.05). Despite this differential response, myonuclear domain size decreased similarly at both ages (P < 0.001). In both young-adult and old rats, denervation-induced atrophy was not preceded by a loss of myonuclei. © 2011 Wiley Periodicals, Inc

Quantitative study of the effects of long-term denervation on the extensor digitorum longus muscle of the rat

Background In order to understand the cellular basis underlying the progressively poorer restorative capacity of long-term denervated muscle, we determined the effects of long-term denervation on the muscle fibers and satellite cell population of the rat extensor digitorum longus (EDL) muscle. Methods In 36 male rats, the right hind legs were denervated, and EDL muscles were removed 2, 4, 7, 12, and 18 months later. Muscles were either fixed for electron microscopic analysis or were dissociated into individual muscle fibers for direct fiber counting or for confocal microscopic analysis. Results The percentage of satellite cells rose from the 2.8% control value to 9.1% at 2 months of denervation; thereafter the percentage decreased to 1.1% at 18 months of denervation. The number of myonuclei per muscle fiber steadily declined from 410 in 4 month control muscle to 158 in 7 month denervated muscle. Up to 7 months of denervation, the total number of muscle fibers per muscle remained relatively constant at somewhat over 5,000. The calculated total satellite cell population in 4 month denervated EDL muscle was the same as that of controls at 65,000, but by 7 months of denervation it had declined to 21,000. With increasing time of denervation, the number of cross-sectional profiles of muscle fibers not containing nuclei rose from 14% in control muscle to 49% in 12 month denervated muscle. This was correlated with a pronounced regular clumping of the nuclei, with pronounced nonnucleated segments between nuclear clumps. Conclusions Increasing times of denervation are accompanied by a pronounced decline in the number of myonuclei per muscle fiber and an initial rise and subsequent fall in satellite cell number. These changes are correlated with a decreasing restorative ability of these muscles over the same periods of denervation. Further work on the proliferative capacity of the remaining satellite cells is necessary before firm quantitative conclusions can be made. Anat. Rec. 248:346-354 1997. © 1997 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34280/1/7_ftp.pd

Testosterone mediates satellite cell activation in denervated rat levator ani muscle

Denervation stimulates quiescent satellite cells in skeletal muscle to reenter the cell cycle. In the androgen-sensitive rat levator ani muscle (LA), this mitotic response to loss of neural input fails to occur in castrated animals. To elucidate the role of androgens in denervation-induced satellite cell proliferation, the denervated LA of castrated rats (Group A) was compared with that of animals infixed with testosterone implants after castration (Group B). Mean myofiber cross-sectional areas (Group A: 362.95 Μm 2 ± 27.74; Group B: 403.13 Μm 2 ± 53.87) and linear nuclear densities (Group A: 74.07 mm −1 ± 17.58; Group B: 104.13 mm −1 ± 4.06) were similar ( P > 0.05) in both groups. The androgen-deprived myofibers of Group A, however, had a significantly lower nuclear content (271.0 ± 74.91 vs. 1,285.80 ± 81.74 in Group B; P < 0.05) on account of their considerably shorter mean length (3.44 mm ± 0.29 vs. 12.31 mm ± 0.92 in Group B; P < 0.05). The proportional representation of satellite cells in hormone-replaced, denervated muscle was more than twice that in the untreated group (Group B: 5.15 ± 0.83% vs. Group A: 2.28 ± 0.23%; P < 0.05). In absolute terms, the satellite cell number in Group B was approximately an order of magnitude greater than in Group A (408.4 × 10 3 vs. 38.08 × 10 3 ). The results confirm the absence of testosterone as the factor responsible for the inability of satellite cells in the LA of castrated rats to respond mitotically to the withdrawal of neural input after denervation. Anat Rec 263:19–24, 2001. © 2001 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34289/1/1072_ftp.pd