‘This restless enemy of all fertility’: exploring paradigms of coastal dune management in Western Europe over the last 700 years

Drifting sand has inundated settlements and damaged agricultural land along the coasts of Western Europe for the last 700 years. The need to control sand migration has been an important driver of the management of coastal sand dunes and here we analyse original archival materials to provide new insights into historically changing coastal dune management practices. Records of coastal sand movement in Denmark, The Netherlands, Britain, Ireland and France were reviewed and three distinct management approaches were identified. The ways in which these approaches have played out in space and time were examined with particular reference to records from landed estates in Britain and Ireland. We demonstrate how historical evidence can be used to inform contemporary debates on dune management strategy and practice. We propose a new place-based approach to the future management of coastal dunes that can incorporate both expert and locally produced ‘knowledges’ and that is underpinned by an understanding of how both natural forces and human interventions have shaped these dune landscapes over time

Etude analytique du fonctionnement des moteurs à réluctance alimentés à fréquence variable

In switched reluctance motors fed by a constant voltage source (like a battery) at high frequencies, the current becomes unpredictable and often cannot reach a given reference value, because of the variation of the inductances with the rotor position ; the “motional” m.m.f. generates commutation troubles which increase with the frequency. An optimal control as well as an approximate design of the motor require a quick and simple calculation of currents, powers and losses ; now, in principle, the non-linear electrical equation needs a numerical resolution, whose results cannot be extrapolated. By linearizing this equation by intervals, the method proposed here allows to express analytically, in any case, the phase currents, the torque and the copper losses, when the feeding voltage itself is constant by intervals. The model neglects saturation, but a simple adjustment of the inductance (chosen ad libitum) allows to deal with it. The calculation is immediate and perfectly accurate as long as the machine parameters themselves are well defined. Some results are given as examples for two usual feeding modes.Dans les machines à réluctance alimentées à haute fréquence par une source à tension constante, comme une batterie, le courant varie de manière difficilement prévisible, à cause de la variation des inductances avec la position du rotor, et souvent ne parvient pas à s'établir à une valeur de consigne imposée ; la f.é.m. “motionnelle” engendre des difficultés de communication qui s'aggravent avec l'augmentation de fréquence jusqu'à empêcher le fonctionnement. Tant pour optimiser la commande que pour dimensionner approximativement un moteur ; on doit pouvoir calculer simplement et rapidement le courant et la puissance ; or l'équation électrique, non linéaire, doit en principe être résolue numériquement et les résultats ne sont pratiquement pas extrapolables. En linéarisant par intervalles cette équation, la méthode proposée ici permer d'exprimer analytiquement et dans tous les cas les courants de phase, la puissance fournie et les pertes Joule, lorsque la tension aux bornes de l'enroulement est constante par morceaux. Le modèle utilisé néglige la saturation ; mais il est possible de tenir compte de celle-ci par des ajustements, facilement calculables, de la courbe d'inductance, quelle que soit son allure. Les calculs sont immédiats et parfaitement précis pour autant que les paramètres soient bien définis. Quelques résultats sont donnés à titre d'exemple, pour deux modes d'alimentation usuels

Equivalence between the method of magnetic images and the variable separation method in the study of some slotless surface permanent magnet synchronous machines

In the present paper, the equivalence between the magnetic images method and the classical variable separation method is set up. These methods are separately applied to calculate the magnetic scalar potentials and the magnetic vector potentials in the air-gap of some cylindrical synchronous machines, excited by surface permanent magnets with radial and/or azimuthal magnetisation, and without polar pieces. The rotor and the stator are assumed slotless, and the whole electric machine non saturated. The expressions of the magnetic scalar potentials of each method are interpreted, and their equivalence is established. The Mayn purpose of this paper is then the demonstration that the magnetic images method is applicable for the study of simplified synchronous machines. The interest of the magnetic images use in comparison with the variable separation method is shown

A la reconquête des forêts. Les Landes, à l'aube d'un nouvel équilibre

Cinq explorations de forêts en pleine renaissance conciliant développement économique et préoccupations écologiques. Dans ce volet : la forêt des Landes composée d’immenses pinèdes qui constituent le moteur économique de l’Aquitaine. Développée par l’homme au XIXe siècle, la forêt des Landes est composée d’immenses pinèdes qui constituent le moteur économique de l’Aquitaine. Depuis le passage de la tempête Klaus, qui a ravagé en janvier 2009 plus de la moitié du massif landais, les forestiers s’emploient à repenser les pratiques en mariant nouvelles technologies et méthodes écologiques, avec la collaboration de scientifiques. Ces derniers préconisent la lutte biologique contre les parasites et l’introduction d’espèces d’arbres plus résistantes. Mais si la polyculture ouvre de nouvelles perspectives, elle représente aussi une rupture radicale avec le modèle d’exploitation en place depuis des décennies

Primary productivity in the recently flooded 'Sep Reservoir' (Puy-de-Dôme, France)

International audienceSeasonal variations in phytoplankton biomass and production were studied in 1996 and 1997 in the newly flooded (1995) Sep Reservoir (France) in relation to various physico-chemical environmental factors. No trophic upsurge occurred in the reservoir as has been found in most of the newly flooded reservoirs. Phytoplankton composition changed drastically from 1996 to 1997, the latter year being characterized by a rarity of diatoms. Areal euphotic chlorophyll a concentration and phytoplankton carbon biomass were typical of mesotrophic lakes in 1996 and of somewhat oligotrophic environments in 1997. In contrast, the primary production (PP) rates were similar in both years, indicating a change in the factors controlling phytoplankton populations from 1996 to 1997. The low PP (compared with the algal biomass present) in 1996 seemed to be related to the instability of the water column and the Zmix:Zeu ratio, whose negative effects on the phytoplankton community were apparently more pronounced in 1996 than in 1997. Orthophosphate concentrations, and their contribution to total phosphorus, remained low in 1996 but increased with time in 1997. The temporal losses of orthophosphates from June to September 1996 accounted for only 42% of the measured PP, indicating that PP in 1996 was also strongly affected by P availability and probably took place due to other P sources such as regenerated nutrients

Radiothérapie adaptative des cancers de la vessie : état de l’art et perspectives pratiques

International audiencePurpose: Radiation therapy (RT) for muscle invasive bladder cancer (MIBC) is challenging, with observed variations in bladder shape and size resulting in inappropriate coverage of the target volumes (CTV). Large margins were historically applied around the CTV, increasing the dose delivered to organs at risk (OAR). With repositioning imaging and visualization of soft tissues during image guided RT, an opportunity to consider these movements and deformations appeared possible with an adaptive RT approach (ART).Materials and methods: A bibliographic search on the PubMed database has been done in January 2019. Studies focusing on patients with MIBC, treating on ART, with the objectives of feasibility, clinical and/or dosimetric evaluation and comparison with a standard irradiation technique were eligible. The purpose of this review was to define the different ART techniques used in clinical practice, to discuss their advantages compared to conventional RT in terms of target volume's coverage and OAR dose and to describe their feasibility in clinical practice.Results: A total of 30 studies were selected. The strategies known as "composite offline", "plan of the day" not individualized or individualized, and "re-optimization" have been identified. All the studies have shown a significant benefit of ART in target coverage and dose of OAR, especially the rectum and small bowel. All ART plans produced are not used during RT sessions. Inter-observer variability for the selection of these plans can be observed. The practical implementation within a department required staff education and training, and increases the duration of treatment preparation. The "A-POLO" approach seems to be the most suitable for practice.Conclusion: ART is the technique of choice for bladder cancer RT. The "plan of the day" approach, individualized according to the A-POLO methodology, seems to be the most effective. The emergence of daily re-optimization, especially using MRI-Linac, is promising. The correlation between dosimetric benefits and clinical efficacy and safety results should be demonstrated into future trials

A la reconquête des forêts. Les Landes, à l'aube d'un nouvel équilibre

Cinq explorations de forêts en pleine renaissance conciliant développement économique et préoccupations écologiques. Dans ce volet : la forêt des Landes composée d’immenses pinèdes qui constituent le moteur économique de l’Aquitaine. Développée par l’homme au XIXe siècle, la forêt des Landes est composée d’immenses pinèdes qui constituent le moteur économique de l’Aquitaine. Depuis le passage de la tempête Klaus, qui a ravagé en janvier 2009 plus de la moitié du massif landais, les forestiers s’emploient à repenser les pratiques en mariant nouvelles technologies et méthodes écologiques, avec la collaboration de scientifiques. Ces derniers préconisent la lutte biologique contre les parasites et l’introduction d’espèces d’arbres plus résistantes. Mais si la polyculture ouvre de nouvelles perspectives, elle représente aussi une rupture radicale avec le modèle d’exploitation en place depuis des décennies

Résultats dosimétriques et cliniques d’une stratégie de radiothérapie adaptativede type “bibliothèque de plans” des cancers de la vessie localisés

International audienceTo account of individual intra-pelvic anatomical variations in muscle invasive bladder cancer (MIBC) irradiation, adaptive radiotherapy (ART) using a personalized plan library may have dosimetric and clinical benefits.Material and methods. The data from ten patients treated for localized MIBC according to the “plan of the day” (P0oD) individualized ART technique were collected and retrospectively analysed. Target volumes and organs at risk (OAR) were delineated at different bladder fill rates, resulting in two or three treatment plans. Daily Cone-Beam CT (CBCT) was used for the selection of PoD at each fraction. Retrospectively, we delineated rectal, intestinal and target volumes on each CBCT, to assess target volume coverage and dose sparing to healthy tissues. A comparison with the conventional radiotherapy technique was performed. The secondary objectives were toxicity and efficacy.Results: The target coverage was respected with the adaptive treatment: 97.3% for the bladder Clinical Target Volume (CTV) (99.5; [60.1-100]) and 98% for the bladder+lymph nodes CTV (98.6; [85.4-100]). Concerning OAR, the volume of healthy tissue spared was 43.7% on average and the V45Gy for the small bowel was 43,4cc (35; [0-129]) (versus 57,6cc). The rectal D50 was on average 18,7Gy for the adaptive treatment (15.9; [2.4-44.1]) versus 17Gy with the conventional approach. With a median follow-up of 2.94 years (95% CI: [0.92-4.02]), we observed three grade 3 toxicities (30%). No grade 4 toxicity was observed. The 2-year overall survival and progression-free survival rates were 65.6% (95% CI: [26-87.6]) and 45.7% (95% CI: [14.3-73]), respectively.Conclusion: The ART technique using a PoD strategy showed a reduction of the irradiated healthy tissue volume while maintaining a similar bladder coverage, with an acceptable rate of toxicity.Objectif de l’étude : pour tenir compte des variations individuelles anatomiques intrapelviennes en cas d’irradiation des tumeurs de la vessie infiltrant le muscle, la radiothérapie adaptative pourrait présenter un bénéfice dosimétrique et clinique.Matériel et méthodes : les données de dix patients pris en charge dans notre centre pour une tumeur de la vessie infiltrant le muscle par radiothérapie adaptative du “plan of the day” (PoD) individualisé ont été analysées rétrospectivement. Lors du scanner de planification, les volumes cibles et organes à risque ont été délinéés à différents taux de remplissage vésical, aboutissant à deux ou trois plans de traitement. Des imageries de positionnement ont été utilisées pour la sélection du PoD à chaque fraction. L’objectif était d’évaluer cette approche en termes de couverture du volume cible et d’épargne de dose aux tissus sains avoisinants, en la comparant à la technique de radiothérapie définie comme classique. Les objectifs secondaires concernaient la toxicité et l’efficacité.Résultats : la couverture cible était respectée avec le traitement adaptatif de 97,3 % pour le volume cible anatomoclinique de la vessie (99,5 ; [60,1–100]) et 98 % pour celui de la vessie et des ganglions (98,6 ; [85,4–100]). S’agissant des organes à risque, le volume de tissu sain épargné était de 43,7 % en moyenne et le volume recevant 45 Gy (V45 Gy) de l’intestin grêle de 43,4cc (35 ; [0–129]) (contre 57,6cc). La dose délivrée dans 50 % (D50) du rectum était en moyenne de 18,7 Gy pour le traitement adaptatif (15,9 ; [2,4–44,1]) contre 17 Gy avec l’approche classique. Avec un recul médian de 2,94 ans (IC95 % [intervalle de confiance à 95 %] : 0,92-4,02), nous avons constaté trois cas de toxicité de grade 3 (30 %). Aucune toxicité de grade 4 n’a été observée. Les taux de survie globale et de survie sans progression à 2 ans étaient respectivement de 65,6 % (IC95 %: 26-87,6) et 45,7 % (IC95 %: 14,3-73).Conclusion : la radiothérapie adaptative utilisant la bibliothèque de plans (PoD) a permis une réduction du volume de tissu sain irradié tout en maintenant une couverture vésicale similaire, avec une toxicité acceptable

The functional importance of bacteriophages in the microbial loop of an oligomesotrophic lake over a diel cycle

The abundances of the different compartments of the microbial loop (i.e., viruses, heterotrophic bacteria, heterotrophic nanoflagellates, and pigmented nanoflagellates), total (TPP) and excreted (EPP) primary production, bacterial production (BP), viral lytic activity (LA), and bacterivory by nanoflagellates (FG) were measured on June 15 and 16, 1998, in a moderate-altitude oligomesotrophic lake (Lac Pavin, France), at 5 and 10 m depths. At both depths, losses of the bacterial community by viral lysis (LA5 m = 1.7 x 106 cells.1-1.h-1, LA10 m = 2.0 x 106 cells.1-1.h-1) were, on average, lower than those due to the grazing activity of flagellates (FG5 m = 10.3 x 106 cells.1-1.h-1 , FG10 m = 8.4 x 106 cells.1-1.h-1). A carbon budget exercise indicated that, for the sampling period and depths, 17.8 % of C from TPP (= 38.1 % of EPP) was used by bacteria. On the other hand, 52.7 % of BP (= 2.15 % of TPP) was grazed by nanoflagellates, while 11.0 % of BP (= 0.45 % of TPP) was lysed by viruses