ParisTech

About: ParisTech is a education organization based out in Paris, France. It is known for research contribution in the topics: Residual stress & Finite element method. The organization has 1888 authors who have published 1965 publications receiving 55532 citations. The organization is also known as: Paris Institute of Technology & ParisTech Développement.

Sagittal rebalancing of the pelvis and the thoracic spine after pedicle subtraction osteotomy at the lumbar level.

Abstract: DESIGN Retrospective study of radiologic records of patients who underwent lumbar pedicle subtraction osteotomy (PSO) procedures. OBJECTIVE To evaluate the restoration of spinal balance above and below the osteotomy site after PSO for various causes. SUMMARY OF BACKGROUND DATA The normal sagittal balance of the spine has been widely documented. Sagittal imbalance can be surgically treated with vertebral osteotomy. Reports have described its technical aspects and local radiologic results. Less is known about the spontaneous rebalancing of the spine cranially and caudally to the osteotomy site. METHODS The French Scoliosis Study Group conducted a multicenter retrospective study from the records of a combined cohort of 356 patients. Spinal balance after PSO was assessed radiologically. In this study, we focused specifically on measuring the reorientation of the pelvis and upper thoracic segments and investigated the influence of pelvic incidence, osteotomy level, and regional lordosis gain. The population was classified according to the indication for the procedure: posttraumatic deformity, degenerative kyphosis, scoliosis, or ankylosing spondylarthritis. RESULTS The average regional lordosis gain was 26.1 degrees. In the degenerative kyphosis and scoliosis groups, the level of osteotomy and the incidence angle tended to influence pelvic adaptation (better balance of the caudal portion was associated with low-level PSO and low-incidence angle). The posttraumatic deformity cases had a specific pattern: balance changes after PSO were limited to the local lordosis gain, with less pelvic and thoracic reorientation, probably due to spinal flexibility. On the contrary, the spondylarthritis cases showed less pelvic and more thoracic reorientation, probably due to hip and spinal stiffness. CONCLUSIONS Better knowledge from a large series of the overall spontaneous spinal balance after PSO and the pelvic/thoracic reorientation would be useful for preoperative planning of lumbar osteotomies and predicting pelvic and hip reorientation. LEVEL OF EVIDENCE Level II.

A Numerical Study of Cavitation Induced Vibration

Abstract: The present work deals with an original study of the dynamics of an elastic structure immerged in an unsteady partial cavitating flow. The latter corresponds to the case of a leading edge attached cavity that exhibits periodical oscillations. The elastic structure is a cantilevered rectangular hydrofoil made of polyacetal plastic material (E = 3GPa). The computational fluid dynamics is based on a 2D unsteady single fluid model of cavitation with a barotropic law and a k – e – RNG modified turbulent model. The computational structure dynamics is carried out using a 3D finite element code. The fluid structure coupling is based on a chained weak coupling algorithm for which the 2D unsteady local fluid loading is computed on a rigid hydrofoil, then interpolated on the 3D deformable hydrofoil to compute the structural dynamics. The results are compared to the experiment ones carried out in the hydrodynamic tunnel of the research institute at the French Naval Academy for flow conditions close to the numerical ones. It is shown that in spite of a weak coupling algorithm, the forced vibration due to the periodical behaviour of the unsteady partial cavity is rather well predicted by the computation and compared favourably with the experiments. However, the experiments reveal that cavitation influences the natural modal response of the elastic structure in a more complex fluid structure interaction process.Copyright © 2010 by ASME

Development projects and land use conflicts in pakistani rural settings an analysis

Abstract: This article describes the impact of the Chotiari water reservoir on socio-economic values and livelihoods in Pakistan and the policy implications of the project, based on deeper analysis. First, it defines the background of the reservoir through the concepts of land distribution with respect to national and international interests. Then the research emphasizes the depletion of natural resource values to rural communities in terms of economic activities and wild resource gathering for rural livelihoods. It highlights the root causes of conflicts with response to land use decisions of the project. Finally, the article offers a discussion on the governance and policy implications of the findings, particularly from a land use conflict perspective.

The Impact of a Radical Innovation on Business Models: Incremental Adjustments or Big Bang?

Abstract: In this paper we study the impact of a radical technological innovation on business models. Do firms react by adjusting their business models incrementally, through iterative steps? Or do such innovations lead, instead, to a big bang of new innovative business models that are all adopted and experimented by the industry? To answer these questions, we analyze the impact of digitization — a radical innovation — on business models in the recorded music industry. Using an economic analysis of the effects of digitization, we begin by building five potential digital business models for the music industry. Then, using data from a survey on a sample of French record companies, we map these record labels on our digital business models. Our analysis suggests that digitization has led to a big bang of business models in the music industry, rather than to incremental adjustments of the existing business model.