151 research outputs found
An optimal control problem for the continuity equation arising in smart charging
This paper is focused on the mathematical modeling and solution of the
optimal charging of a large population of identical plug-in electric vehicles
(PEVs) with mixed state variables (continuous and discrete). A mean field
assumption is formulated to describe the evolution interaction of the PEVs
population. The optimal control of the resulting continuity equation of the
mixed system under state constraints is investigated. We prove the existence of
a minimizer. We then characterize the solution as the weak solution of a system
of two coupled PDEs: a continuity equation and of a Hamilton-Jacobi equation.
We provide regularity results of the optimal feedback control
DISSOLUTION OF AEROSOL IRON IN SEA WATER USING FLOW-INJECTION WITH CHEMILUMINESCENCE DETECTION
Iron is an essential micronutrient for the metabolism of marine organisms and
impacts on primary productivity and hence indirectly on climate change. The dominant
source of iron to the sea surface in open ocean regions is from the atmosphere by aeolian
dust transport but the solubility of iron from dust is poorly constrained. In this thesis,
chemical and physical factors impacting on the process of dust dissolution and iron
release in seawater were investigated using FI-CL detection.
A manual FI manifold was automated and optimised for the determination of iron,
at nanomolar concentrations, released from aerosols in seawater. The limit of detection
was 0.04 ± 0.03 nM and the precision (rsd) ranged from 0.2 to 10.8%. Protocols,
maintenance find troubleshooting sections were documented for effective utilisation o f the
technique. A seawater treatment system to produce low DOC (dissolved organic carbon)
and dFe (dissolved iron) seawater was adapted and optimised. This UV photo-oxidation
system was poorly efficient in removing DOC (-40%), complexing ligands (~60%) and
dFe (apparent removal 90%).
An autosampler was designed, validated, and integrated with an incubation system
for sub-sampling during dissolution experiments of aerosol iron in seawater. Fast release
of iron f r om the aerosol particles occurred within the first 2 h, followed by a decrease over
1 day. Preliminary experiments w i t h UV-irradiated seawater exhibited lower solubilities
compared w i t h non UV-irradiated seawater. High dust concentrations gave lower final
solubilities compared with low dust concentrations. A 24 h kinetic study was carried out
using NIST 1648 under contrasting light and dark regimes. Dissolution of the endmember
under dark conditions released 0.36% of the iron whilst the addition of 20 nM to
200 nM Desferrioxamine B (DFOB) stimulated a release of 0.90 to 1.6%. In light, the
release of iron was 0.50% with aerosol, whilst the addition of DFOB (20 nM) induced an
adsorption (-1.18%).
Iron release from aerosol samples from three sites around the Eastern
Mediterranean: Erdemli, Tel-Shikmona and Heraklion was determined in a NATO
funded project. The solubility of contrasting aerosol populations from crustal and
anthropogenic sources was investigated. Crustally derived aerosol samples exhibited a
variable kinetic profile of iron release with an average of maximum solubility of 0.39 ±
0.52%. The anthropogenically influenced aerosol samples exhibited consistent kinetic
profiles (fast release < 2 h) with an average of maximum solubility of 10.6 ± 8.9%. From
these results, an approximation of the atmospheric dry inputs of soluble iron in seawater
to the Levantine Basin was calculated for the first time, ranging from 804 ± 910 t for the
Northern Levantine Basin to 2,670 ± 3,050 t for the Southern Levantine Basin
Sur l'extension, le style et l'ùge de mise en place de la nappe de Gavarnie (Pyrénées centrales)
Novel Fat DepotâSpecific Mechanisms Underlie Resistance to Visceral Obesity and Inflammation in 11ÎČ-Hydroxysteroid Dehydrogenase Type 1âDeficient Mice
Mammography-based screening program: preliminary results from a first 2-year round in a Brazilian region using mobile and fixed units
RLH, TBS and ALF made substantial contributions to the conception and
design of the article, the acquisition, analysis and interpretation of the data,
and drafting of the article. ECM, JSCM and NB made substantial
contributions to the conception and design of the study.Background: Breast cancer is the most frequently diagnosed cancer and the leading cause of cancer deaths
among women worldwide. The use of mobile mammography units to offer screening to women living in remote
areas is a rational strategy to increase the number of women examined. This study aimed to evaluate results from
the first 2 years of a government-organized mammography screening program implemented with a mobile unit
(MU) and a fixed unit (FU) in a rural county in Brazil. The program offered breast cancer screening to women living
in Barretos and the surrounding area.
Methods: Based on epidemiologic data, 54 238 women, aged 40 to 69 years, were eligible for breast cancer
screening. The study included women examined from April 1, 2003 to March 31, 2005. The chi-square test and
Bonferroni correction analyses were used to evaluate the frequencies of tumors and the importance of clinical
parameters and tumor characteristics. Significance was set at p < 0.05.
Results: Overall, 17 964 women underwent mammography. This represented 33.1% of eligible women in the area.
A mean of 18.6 and 26.3 women per day were examined in the FU and MU, respectively. Seventy six patients were
diagnosed with breast cancer (41 (54%) in the MU). This represented 4.2 cases of breast cancer per 1000
examinations. The number of cancers detected was significantly higher in women aged 60 to 69 years than in
those aged 50 to 59 years (p < 0.001) or 40 to 49 years (p < 0.001). No difference was observed between women
aged 40 to 49 years and those aged 50 to 59 years (p = 0.164). The proportion of tumors in the early (EC 0 and EC
I) and advanced (CS III and CS IV) stages of development were 43.4% and 15.8%, respectively.
Conclusions: Preliminary results indicate that this mammography screening program is feasible for implementation
in a rural Brazilian territory and favor program continuation
Mouvements collectifs et structure sociale chez le zebrafish en environnement fragmenté.
The collective decision-making is one of the mecanisms used by social species during foraging, path optimisation, collective movements, predator avoidance or habitat selection. Zebrafish (Danio rerio), gregarious animal models in biology, have never been studied in the context of collective binary choices. We found logical to analyse their decision behaviours. The goal of this thesis is to meet the expectations of the ASSISI|bf project of creation of an andjustable experimental setup able to sustain robots and fish, of development of an adaptive and self-organised mixed society and of the caracterisation of individual and collective behaviours of the zebrafish, implementable in the robots. We show that the collective decision making and the cohesion of groups of zebrafish in an open environment, composed of two identical landmarks, are dynamical processes that vary in function of the strain of Danio rerio (AB or TL) and are related to the density of the populations. Always on the move, the fish oscillate between the two landmarks. The AB zebrafish are more attracted by the landmarks and are less cohesive than the TL zebrafish. In a contrained environment, two rooms connected by a corridor, we do the same type of experiments with only AB zebrafish and vary the density of the groups from 1 to 20 individuals. AB zebrafish swim together. The increase of the density of the groups make them split. We noticed that the density of the groups has an effect on the topology of the groups : during collective departures from a room to the other one, there is a correlation between the rank of exit of the zebrafish (followers) and the rank of the distances of each individual from the initiator of the exits. This correlation is higher when the followers are either the closest or the farest from the initiator.Using the previous experimental setup, we focused also on the topics related to leadership for groups of 2 to 10 individuals. We show that each fish intiate at least once a collective departure and that the number of initiations is proportional to the number of initiation attempts. Also, we found that all the fish have the same success rate in the initiations after an initiation attempt and that there is a positive correlation between the intiations and the average speed. A deeper analysis of the collective movements shows that the zebrafish swim in group and transit without any interruption or even without periodicity between the rooms. We are currently improving this study and will bring new points of comparison to check if the non-periodicity of the transitions could be related to the density of the groups. Finally, we developed a new version of the Y-maze based on the previous observations.This perpetual Y-maze shows many usefull features for the study of the behaviour : a low habituation rate, a reduction of the interactions between the animals and the experimentators, and allows the fish to move in a Y-maze without starting nor ending zones as in typical Y-mazeLa prise de dĂ©cision collective est un des mĂ©canismes usitĂ©s par les espĂšces sociales lors dâĂ©vĂ©nements de collectes de nourriture, dâoptimisation de chemins, de mouvements collectifs, de fuites face Ă un prĂ©dateur ou bien mĂȘme de sĂ©lections dâhabitat. Les zebrafish (Danio rerio), animaux grĂ©gaires de rĂ©fĂ©rence en biologie, nâont jamais Ă©tĂ© Ă©tudiĂ©s dans des contextes de choix collectifs binaires et ils nous semblait lĂ©gitime dâanalyser leurs comportements dĂ©cisionnels. Lâobjectif de cette thĂšse est de rĂ©pondre aux attentes du projet ASSISI|bf de crĂ©ation dâun systĂšme expĂ©rimental modulable capable dâaccueillir robots comme poissons, de mise au point dâune sociĂ©tĂ© mixte adaptative auto-organisĂ©e, et de caractĂ©risation des comportements individuels et collectifs des zebrafish implĂ©mentables dans les robots. Nos observations montrent que la prise collective de dĂ©cision et la cohĂ©sion des groupes en environnement ouvert, et prĂ©sentant deux points de repĂšre identiques, sont des processus dynamiques qui varient selon la souche de Danio rerio (AB ou TL) et sont liĂ©es Ă la densitĂ© des populations. Constamment en mouvement, les poissons oscillent entre les deux points de repĂšre identiques installĂ©s dans leur environnement. La souche AB est toujours plus attirĂ©e par ces hĂ©tĂ©rogĂ©nĂ©itĂ©s et est beaucoup moins cohĂ©sive que la souche TL. En environnement contraint, de type deux chambres reliĂ©es par un couloir, nous rĂ©itĂ©rons le mĂȘme type dâexpĂ©rience chez la souche la plus Ă mĂȘme de prendre des dĂ©cisions collectivement (AB) et en faisant varier la densitĂ© des groupes de 1 Ă 20 individus. Il ressort que les Danio rerio de type AB restent essentiellement en groupe mais que lâaugmentation de leur densitĂ© tend Ă les diviser. Nous remarquons aussi que la densitĂ© influe partiellement sur la topologie du groupe : il existe, lors des sorties collectives, une corrĂ©lation entre lâordre de sortie des zebrafish (les suiveurs) et lâordre de distance de chaque individu par rapport Ă lâinitiateur desdites sorties. Cette corrĂ©lation est dâautant plus forte quand les suiveurs sont soit trĂšs proches, soit les plus Ă©loignĂ©s de lâinitiateur. Le dispositif expĂ©rimental prĂ©cĂ©dent nous permet dâautre part de nous concentrer sur la notion de leadership chez des groupes de 2 Ă 10 Danio rerio AB. Nous mettons en Ă©vidence que chaque poisson initie au moins une fois un dĂ©part collectif, le nombre dâinitiations effectives est proportionnel au nombre de tentatives dâinitiations, que tous les poissons prĂ©sentent le mĂȘme taux de succĂšs dâinitiation aprĂšs une tentative et quâil existe une corrĂ©lation positive entre initiations et vitesse moyenne de nage.Une analyse poussĂ©e des mouvements collectifs nous fait constater que les zebrafish se dĂ©placent essentiellement en groupe et transitent sans interruption ni pĂ©riodicitĂ© entre les chambres. Nous sommes actuellement en train dâamĂ©liorer cette Ă©tude en apportant de nouveaux points de comparaison afin de vĂ©rifier si la non-pĂ©riodicitĂ© des transitions entre les chambres est liĂ©e Ă la densitĂ© des groupes testĂ©s. Enfin, nous nous inspirons du prĂ©cĂ©dent systĂšme expĂ©rimental â les deux chambres reliĂ©es par un couloir â pour crĂ©er une version actualisĂ©e dâun labyrinthe en Y. Ce labyrinthe en Y est dit perpĂ©tuel car il combine tout le savoir faire que nous avons dĂ©veloppĂ© dans lâĂ©laboration des prĂ©cĂ©dents systĂšmes expĂ©rimentaux : une faible habituation des zebrafish pour leur milieu, une rĂ©duction des interactions entre lâexpĂ©rimentateur et les animaux et la possibilitĂ© pour les poissons de circuler dans un labyrinthe Ă symĂ©trie centrale, sans zone de dĂ©part ni zone de fin formalisĂ©es (typiques des labyrinthes en Y
La fonction logistique, un outil performant d'analyse et de prévision à moyen terme. Application à la production de pétrole et de gaz aux Etats-Unis, en URSS et dans d'autres pays
A partir de la similitude observée entre l'évolution de la production pétroliÚre d'un pays et celle de la pénétration d'un produit dans un marché (fonction logistique), l'auteur expose le principe d'une méthode originale qui permet, sous certaines conditions, de prévoir quelle sera la production annuelle probable d'un pays producteur à un horizon de 10 à 15 ans. La validité de cette méthode est d'abord démontrée sur l'exemple de la production pétroliÚre aux Etats-Unis. Elle est ensuite illustrée par les résultats obtenus pour un certain nombre de pays : production future de gaz aux Etats-Unis, production pétroliÚre future du Canada, de l'URSS, du Venezuela et de l'ensemble du monde hors Moyen-Orient
Collective movements and social structure of the zebrafish in a fragmented environment
La prise de dĂ©cision collective est un des mĂ©canismes usitĂ©s par les espĂšces sociales lors dâĂ©vĂ©nements de collectes de nourriture, dâoptimisation de chemins, de mouvements collectifs, de fuites face Ă un prĂ©dateur ou bien mĂȘme de sĂ©lections dâhabitat. Les zebrafish (Danio rerio), animaux grĂ©gaires de rĂ©fĂ©rence en biologie, nâont jamais Ă©tĂ© Ă©tudiĂ©s dans des contextes de choix collectifs binaires et ils nous semblait lĂ©gitime dâanalyser leurs comportements dĂ©cisionnels. Lâobjectif de cette thĂšse est de rĂ©pondre aux attentes du projet ASSISI|bf de crĂ©ation dâun systĂšme expĂ©rimental modulable capable dâaccueillir robots comme poissons, de mise au point dâune sociĂ©tĂ© mixte adaptative auto-organisĂ©e, et de caractĂ©risation des comportements individuels et collectifs des zebrafish implĂ©mentables dans les robots. Nos observations montrent que la prise collective de dĂ©cision et la cohĂ©sion des groupes en environnement ouvert, et prĂ©sentant deux points de repĂšre identiques, sont des processus dynamiques qui varient selon la souche de Danio rerio (AB ou TL) et sont liĂ©es Ă la densitĂ© des populations. Constamment en mouvement, les poissons oscillent entre les deux points de repĂšre identiques installĂ©s dans leur environnement. La souche AB est toujours plus attirĂ©e par ces hĂ©tĂ©rogĂ©nĂ©itĂ©s et est beaucoup moins cohĂ©sive que la souche TL. En environnement contraint, de type deux chambres reliĂ©es par un couloir, nous rĂ©itĂ©rons le mĂȘme type dâexpĂ©rience chez la souche la plus Ă mĂȘme de prendre des dĂ©cisions collectivement (AB) et en faisant varier la densitĂ© des groupes de 1 Ă 20 individus. Il ressort que les Danio rerio de type AB restent essentiellement en groupe mais que lâaugmentation de leur densitĂ© tend Ă les diviser. Nous remarquons aussi que la densitĂ© influe partiellement sur la topologie du groupe : il existe, lors des sorties collectives, une corrĂ©lation entre lâordre de sortie des zebrafish (les suiveurs) et lâordre de distance de chaque individu par rapport Ă lâinitiateur desdites sorties. Cette corrĂ©lation est dâautant plus forte quand les suiveurs sont soit trĂšs proches, soit les plus Ă©loignĂ©s de lâinitiateur. Le dispositif expĂ©rimental prĂ©cĂ©dent nous permet dâautre part de nous concentrer sur la notion de leadership chez des groupes de 2 Ă 10 Danio rerio AB. Nous mettons en Ă©vidence que chaque poisson initie au moins une fois un dĂ©part collectif, le nombre dâinitiations effectives est proportionnel au nombre de tentatives dâinitiations, que tous les poissons prĂ©sentent le mĂȘme taux de succĂšs dâinitiation aprĂšs une tentative et quâil existe une corrĂ©lation positive entre initiations et vitesse moyenne de nage.Une analyse poussĂ©e des mouvements collectifs nous fait constater que les zebrafish se dĂ©placent essentiellement en groupe et transitent sans interruption ni pĂ©riodicitĂ© entre les chambres. Nous sommes actuellement en train dâamĂ©liorer cette Ă©tude en apportant de nouveaux points de comparaison afin de vĂ©rifier si la non-pĂ©riodicitĂ© des transitions entre les chambres est liĂ©e Ă la densitĂ© des groupes testĂ©s. Enfin, nous nous inspirons du prĂ©cĂ©dent systĂšme expĂ©rimental â les deux chambres reliĂ©es par un couloir â pour crĂ©er une version actualisĂ©e dâun labyrinthe en Y. Ce labyrinthe en Y est dit perpĂ©tuel car il combine tout le savoir faire que nous avons dĂ©veloppĂ© dans lâĂ©laboration des prĂ©cĂ©dents systĂšmes expĂ©rimentaux : une faible habituation des zebrafish pour leur milieu, une rĂ©duction des interactions entre lâexpĂ©rimentateur et les animaux et la possibilitĂ© pour les poissons de circuler dans un labyrinthe Ă symĂ©trie centrale, sans zone de dĂ©part ni zone de fin formalisĂ©es (typiques des labyrinthes en Y)The collective decision-making is one of the mecanisms used by social species during foraging, path optimisation, collective movements, predator avoidance or habitat selection. Zebrafish (Danio rerio), gregarious animal models in biology, have never been studied in the context of collective binary choices. We found logical to analyse their decision behaviours. The goal of this thesis is to meet the expectations of the ASSISI|bf project of creation of an andjustable experimental setup able to sustain robots and fish, of development of an adaptive and self-organised mixed society and of the caracterisation of individual and collective behaviours of the zebrafish, implementable in the robots. We show that the collective decision making and the cohesion of groups of zebrafish in an open environment, composed of two identical landmarks, are dynamical processes that vary in function of the strain of Danio rerio (AB or TL) and are related to the density of the populations. Always on the move, the fish oscillate between the two landmarks. The AB zebrafish are more attracted by the landmarks and are less cohesive than the TL zebrafish. In a contrained environment, two rooms connected by a corridor, we do the same type of experiments with only AB zebrafish and vary the density of the groups from 1 to 20 individuals. AB zebrafish swim together. The increase of the density of the groups make them split. We noticed that the density of the groups has an effect on the topology of the groups : during collective departures from a room to the other one, there is a correlation between the rank of exit of the zebrafish (followers) and the rank of the distances of each individual from the initiator of the exits. This correlation is higher when the followers are either the closest or the farest from the initiator.Using the previous experimental setup, we focused also on the topics related to leadership for groups of 2 to 10 individuals. We show that each fish intiate at least once a collective departure and that the number of initiations is proportional to the number of initiation attempts. Also, we found that all the fish have the same success rate in the initiations after an initiation attempt and that there is a positive correlation between the intiations and the average speed. A deeper analysis of the collective movements shows that the zebrafish swim in group and transit without any interruption or even without periodicity between the rooms. We are currently improving this study and will bring new points of comparison to check if the non-periodicity of the transitions could be related to the density of the groups. Finally, we developed a new version of the Y-maze based on the previous observations.This perpetual Y-maze shows many usefull features for the study of the behaviour : a low habituation rate, a reduction of the interactions between the animals and the experimentators, and allows the fish to move in a Y-maze without starting nor ending zones as in typical Y-maz
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