Search results for "points"
showing 10 items of 415 documents
Second order optimality conditions in the smooth case and applications in optimal control
2007
International audience; The aim of this article is to present algorithms to compute the first conjugate time along a smooth extremal curve, where the trajectory ceases to be optimal. It is based on recent theoretical developments of geometric optimal control, and the article contains a review of second order optimality conditions. The computations are related to a test of positivity of the intrinsic second order derivative or a test of singularity of the extremal flow. We derive an algorithm called COTCOT (Conditions of Order Two and COnjugate times), available on the web, and apply it to the minimal time problem of orbit transfer, and to the attitude control problem of a rigid spacecraft. …
Minimum fuel control of the planar circular restricted three-body problem
2012
The circular restricted three-body problem is considered to model the dynamics of an artificial body submitted to the attraction of two planets. Minimization of the fuel consumption of the spacecraft during the transfer, e.g. from the Earth to the Moon, is considered. In the light of the controllability results of Caillau and Daoud (SIAM J Control Optim, 2012), existence for this optimal control problem is discussed under simplifying assumptions. Thanks to Pontryagin maximum principle, the properties of fuel minimizing controls is detailed, revealing a bang-bang structure which is typical of L1-minimization problems. Because of the resulting non-smoothness of the Hamiltonian two-point bound…
Famille à un paramètre de coniques utilisant des courbes de Bézier à poids complexes
2019
The paper deals with conics in a rational Bézier representation based on mass points where the weights are complex numbers here. A special representation of conics using weighted points and vectors offers a calculus flexibility in the handle elementary geometrical transformations as rotations, homotheties and direct similarity transformations. Some examples are proposed to the reader.
Hollywood et l’ergonomie des vidéos pour la formation: Effet de la continuité des points de vue de la caméra dans l’apprentissage d’une procédure méd…
2021
International audience; La conception de vidéos éducatives selon des principes cinématographiques peut affecter leur efficacité potentielle pour l'apprentissage. L'objectif de la présente expérience était d'étudier l'effet de la continuité filmique dans l'apprentissage d'une procédure médicale dans la formation aux soins infirmiers. Nous avons testé l'effet de la violation de la règle des 180° qui propose que la caméra doit rester du même côté d'un axe imaginaire de 180° lorsqu'un événement en cours est filmé. Dans une expérience de type pré-post tests, 56 étudiants en soins infirmiers ont été répartis en deux groupes pour apprendre une procédure de réanimation cardiopulmonaire à partir d'u…
Focal Points in Collective Free Improvisation
2013
OLLECTIVE FREE IMPROVISATION (herein abbreviated as CFI), while not a recent phenomenon in music (free jazz’s first experiments date from the late 1950s), remains under-studied. The extant literature either deals with political aspects (Carles and Comolli 2000) or tries to analyze the resulting music, using musicological tools (Jost 1994) or new concepts drawn from the complexity sciences (Borgo 2005). My research on CFI focuses on a cognitive approach, in order to understand the process of collective improvisation: 1 how a group of improvisers who do not know each other and are not using a common referent 2 (Pressing 1988) can answer the challenge of making music together. This paper deals…
Parental and professional agency in terminations for fetal anomalies: analysis of Finnish women's accounts
2013
This study explores the construction of parental and professional agency in the written accounts by women who have undergone selective abortion (N=8). The analysis of the data was based on qualitative, linguistic discourse analysis. The accounts indicate that the mothers themselves exhibited both strong and weak agency during the process of prenatal diagnosis. The role of the professionals was usually discussed in these accounts concerning only the phases of pregnancy when something out of ordinary had been detected. After the termination, the mothers expressed that they were forced to exhibit strong agency and find ways to cope with their distress unaided due to a lack of professional supp…
Extracellular Vesicles and Tumor-Immune Escape: Biological Functions and Clinical Perspectives
2020
The modulation of the immune system is one of the hallmarks of cancer. It is now widely described that cancer cells are able to evade the immune response and thus establish immune tolerance. The exploration of the mechanisms underlying this ability of cancer cells has always attracted the scientific community and is the basis for the development of new promising cancer therapies. Recent evidence has highlighted how extracellular vesicles (EVs) represent a mechanism by which cancer cells promote immune escape by inducing phenotypic changes on different immune cell populations. In this review, we will discuss the recent findings on the role of tumor-derived extracellular vesicles (TEVs) in re…
New 1,2,4-oxadiazole nortopsentin derivatives with cytotoxic activity
2019
New analogs of nortopsentin, a natural 2,4-bis(3&prime
The Putative Metal Coordination Motif in the Endonuclease Domain of Human Parvovirus B19 NS1 Is Critical for NS1 Induced S Phase Arrest and DNA Damage
2011
The non-structural proteins (NS) of the parvovirus family are highly conserved multi-functional molecules that have been extensively characterized and shown to be integral to viral replication. Along with NTP-dependent helicase activity, these proteins carry within their sequences domains that allow them to bind DNA and act as nucleases in order to resolve the concatameric intermediates developed during viral replication. The parvovirus B19 NS1 protein contains sequence domains highly similar to those previously implicated in the above-described functions of NS proteins from adeno-associated virus (AAV), minute virus of mice (MVM) and other non-human parvoviruses. Previous studies have show…
Antecedents of Market Orientation in The Banking Sector During Its Digital Transformation
2019
Firms are under increasing pressure to remain relevant for their customers and need to rethink how to remain market-oriented in the digital age. This is evident in the banking sector where the traditional banks are gradually being challenged by digital native competitors and growing customer demands. Consequently, this study examines what it takes to be market oriented in the banking sector at the age of increasing digitalization. Specifically, we focus on developing the theory on the antecedents of MO and examine how banks can regain market orientation under changing market conditions. Although Market Orientation (MO) has been a widely studied concept that has been applied in numerous diff…