Growth and yield of red raspberries cultivated under open field condition vs. high tunnel or rain shelter in the northern canadian climate

La culture sous abris avec des infrastructures de type grands tunnels est une nouvelle technologie permettant d’améliorer la production de framboises rouges sous des climats nordiques. L’objectif principal de ce projet de doctorat était d’étudier les performances de ces technologies (grands tunnels vs. abris parapluie de type Voen, en comparaison à la culture en plein champ) et leur effets sur le microclimat, la photosynthèse, la croissance des plantes et le rendement en fruits pour les deux types de framboisiers non-remontants et remontants (Rubus idaeus, L.). Puisque les pratiques culturales doivent être adaptées aux différents environnements de culture, la taille d’été (pour le cultivar non-remontant), l’optimisation de la densité des tiges (pour le cultivar remontant) et l’utilisation de bâches réfléchissantes (pour les deux types des framboisiers) ont été étudiées sous grands tunnels, abris Voen vs. en plein champ. Les plants cultivés sous grands tunnels produisent en moyenne 1,2 et 1,5 fois le rendement en fruits commercialisables que ceux cultivés sous abri Voen pour le cv. non-remontant ‘Jeanne d’Orléans’ et le cv. remontant ‘Polka’, respectivement. Comparativement aux framboisiers cultivés aux champs, le rendement en fruits des plants sous grands tunnels était plus du double pour le cv. ‘Jeanne d’Orléans’ et près du triple pour le cv. ‘Polka’. L’utilisation de bâches réfléchissantes a entrainé un gain significatif sur le rendement en fruits de 12% pour le cv. ‘Jeanne d’Orléans’ et de 17% pour le cv. ‘Polka’. La taille des premières ou deuxièmes pousses a significativement amélioré le rendement en fruits du cv. ‘Jeanne d’Orléans’ de 26% en moyenne par rapport aux framboisiers non taillés. Des augmentations significatives du rendement en fruits de 43% et 71% du cv. ‘Polka’ ont été mesurées avec l’accroissement de la densité à 4 et 6 tiges par pot respectivement, comparativement à deux tiges par pot. Au cours de la période de fructification du cv. ‘Jeanne d’Orléans’, les bâches réfléchissantes ont augmenté significativement la densité de flux photonique photosynthétique (DFPP) réfléchie à la canopée inférieure de 80% en plein champ et de 60% sous grands tunnels, comparativement à seulement 14% sous abri Voen. Durant la saison de fructification du cv. ‘Polka’, un effet positif de bâches sur la lumière réfléchie (jusqu’à 42%) a été mesuré seulement en plein champ. Dans tous les cas, les bâches réfléchissantes n’ont présenté aucun effet significatif sur la DFPP incidente foliaire totale et la photosynthèse. Pour le cv. ‘Jeanne d’Orléans’, la DFPP incidente sur la feuille a été atténuée d’environ 46% sous le deux types de revêtement par rapport au plein champ. Par conséquent, la photosynthèse a été réduite en moyenne de 43% sous grands tunnels et de 17% sous abris Voen. Des effets similaires ont été mesurés pour la DFPP incidente et la photosynthèse avec le cv. Polka. En dépit du taux de photosynthèse des feuilles individuelles systématiquement inférieur à ceux mesurés pour les plants cultivés aux champs, la photosynthèse de la plante entière sous grands tunnels était de 51% supérieure à celle observée au champ pour le cv. ‘Jeanne d’Orléans’, et 46% plus élevée pour le cv. ‘Polka’. Ces résultats s’expliquent par une plus grande (près du double) surface foliaire pour les plants cultivés sous tunnels, qui a compensé pour le plus faible taux de photosynthèse par unité de surface foliaire. Les températures supra-optimales des feuilles mesurées sous grands tunnels (6.6°C plus élevé en moyenne que dans le champ), ainsi que l’atténuation de la DFPP incidente (env. 43%) par les revêtements de tunnels ont contribué à réduire le taux de photosynthèse par unité de surface foliaire. La photosynthèse de la canopée entière était étroitement corrélée avec le rendement en fruits pour les deux types de framboisiers rouges cultivés sous grands tunnels ou en plein champ.

Simulations of droplet dispersion in the wakes of cylinders and icing tunnel spray bars

Simulations of droplet dispersion behind cylinder wakes and downstream of icing tunnel spray bars were conducted. In both cases, a range of droplet sizes were investigated numerically with a Lagrangian particle trajectory approach while the turbulent air flow was investigated with a hybrid Reynolds-Averaged Navier-Stokes/Large-Eddy Simulations approach scheme. In the first study, droplets were injected downstream of a cylinder at sub-critical conditions (i.e. with laminar boundary layer separation). A stochastic continuous random walk (CRW) turbulence model was used to capture the effects of sub-grid turbulence. Small inertia droplets (characterized by small Stokes numbers) were affected by both the large-scale and small-scale vortex structures and closely followed the air flow, while exhibiting a dispersion consistent with that of a scalar flow field. Droplets with intermediate Stokes numbers were centrifuged by the vortices to the outer edges of the wake, yielding an increased dispersion. Large Stokes number droplets were found to be less responsive to the vortex structures and exhibited the least dispersion. Particle concentration was also correlated with vorticity distribution which yielded preferential bias effects as a function of different particle sizes. This trend was qualitatively similar to results seen in homogenous isotropic turbulence, though the influence of particle inertia was less pronounced for the cylinder wake case. A similar study was completed for droplet dispersion within the Icing Research Tunnel (IRT) at the NASA Glenn Research Center, where it is important to obtain a nearly uniform liquid water content (LWC) distribution in the test section (to recreate atmospheric icing conditions).. For this goal, droplets are diffused by the mean and turbulent flow generated from the nozzle air jets, from the upstream spray bars, and from the vertical strut wakes. To understand the influence of these three components, a set of simulations was conducted with a sequential inclusion of these components. Firstly, a jet in an otherwise quiescent airflow was simulated to capture the impact of the air jet on flow turbulence and droplet distribution, and the predictions compared well with experimental results. The effects of the spray bar wake and vertical strut wake were then included with two more simulation conditions, for which it was found that the air jets were the primary driving force for droplet dispersion, i.e. that the spray bar and vertical strut wake effects were secondary.

Temporal and spatial variation in temperature experienced by macrofauna at main endeavour Hydrothermal vent field

A significant focus of hydrothermal vent ecological studies has been to understand how species cope with various stressors through physiological tolerance and biochemical resistance. Yet, the environmental conditions experienced by vent species have not been well characterized. This objective requires continuous observations over time intervals that can capture environmental variability at scales that are relevant to animals. We used autonomous temperature logger arrays (four roughly parallel linear arrays of 12 loggers spaced every 10–12 cm) to study spatial and temporal variations in the thermal regime experienced by hydrothermal vent macrofauna at a diffuse flow vent. Hourly temperatures were recorded over eight months from 2010 to 2011 at Grotto vent in the Main Endeavour vent field on the Juan de Fuca Ridge, a focus area of the Ocean Networks Canada cabled observatory. The conspicuous animal assemblages in video footage contained Ridgeia piscesae tubeworms, gastropods (primarily Lepetodrilus fucensis), and polychaetes (polynoid scaleworms and the palm worm Paralvinella palmiformis). Two dimensional spatial gradients in temperature were generally stable over the deployment period. The average temperature recorded by all arrays, and in some individual loggers, revealed distinctive fluctuations in temperature that often corresponded with the tidal cycle. We postulate that this may be related to changes in bottom currents or fluctuations in vent discharge. A marked transient temperature increase lasting over a period of days was observed in April 2011. While the distributions and behavior of Juan de Fuca Ridge vent invertebrates may be partially constrained by environmental temperature and temperature tolerance, except for the one transient high-temperature event, observed fluid temperatures were generally similar to the thermal preferences for some species, and typically well below lethal temperatures for all species. Average temperatures of the four arrays ranged from 4.1 to 11.0 °C during the deployment, indicating that on an hourly timescale the temperature conditions in this tubeworm community were fairly moderate and stable. The generality of these findings and behavioural responses of vent organisms to predictable rhythmicity and non-periodic temperature shifts are areas for further investigation

Biogeographical distribution of Rimicaris exoculata resident gut epibiont communities along the Mid-Atlantic Ridge hydrothermal vent sites

Rimicaris exoculata is a deep-sea hydrothermal vent shrimp which enlarged gill chamber houses a complex trophic epibiotic community. Its gut harbours an autochthonous and distinct microbial community. This species dominates hydrothermal ecosystems megafauna along the Mid-Atlantic Ridge, regardless of contrasted geochemical conditions prevailing in them. Here, the resident gut epibiont community at four contrasted hydrothermal vent sites (Rainbow/TAG/Logatchev/Ashadze) was analysed and compiled with previous data to evaluate the possible influence of site location, using 16S rRNA surveys and microscopic observations (TEM, SEM and FISH analyses). Filamentous epibionts inserted between the epithelial cells microvilli were observed on all examined samples. Results confirmed resident gut community affiliation to Deferribacteres, Mollicutes, Epsilonproteobacteria and to a lesser extent Gammaproteobacteria lineages. Still a single Deferribacteres phylotype was retrieved at all sites. Four Mollicutes-related OTUs were distinguished, one being only identified on Rainbow specimens. The topology of ribotypes median-joining networks illustrated a community diversification possibly following demographic expansions, suggesting a more ancient evolutionary history and/or a larger effective population size at Rainbow. Finally, the gill chamber community distribution was also analysed through ribotypes networks based on sequences from R. exoculata collected at Rainbow/Snake Pit/TAG/Logatchev/Ashadze sites. Results allow refining hypotheses on the epibiont role and transmission pathways.

Peripheral communities of the Eastern Lau Spreading Center and Valu Fa Ridge: community composition, temporal change and comparison to near-vent communities

Western Pacific hydrothermal vents will soon be subjected to deep-sea mining and peripheral sites are considered the most practical targets. The limited information on community dynamics and temporal change in these communities makes it difficult to anticipate the impact of mining activities and recovery trajectories. We studied community composition of peripheral communities along a cline in hydrothermal chemistry on the Eastern Lau Spreading Center and Valu Fa Ridge (ELSC-VFR) and also studied patterns of temporal change. Peripheral communities located in the northern vent fields of the ELSC-VFR are significantly different from those in the southern vent fields. Higher abundances of zoanthids and anemones were found in northern peripheral sites and the symbiont-containing mussel Bathymodiolus brevior, brisingid seastars and polynoids were only present in the northern peripheral sites. By contrast, certain faunal groups were seen only in the southern peripheral sites, such as lollipop sponges, pycnogonids and ophiuroids. Taxonomic richness of the peripheral communities was similar to that of active vent communities, due to the presence of non-vent endemic species that balanced the absence of species found in areas of active venting. The communities present at waning active sites resemble those of peripheral sites, indicating that peripheral species can colonize previously active vent sites in addition to settling in the periphery of areas of venting. Growth and mortality were observed in a number of the normally slow-growing cladorhizid stick sponges, indicating that these animals may exhibit life history strategies in the vicinity of vents that differ from those previously recorded. A novel facultative association between polynoids and anemones is proposed based on their correlated distributions.

Investigation of test time at undertailored conditions in a shock tunnel.

Cover title.

Carpal tunnel syndrome and computer exposure at work in two large complementary cohorts.

International audience

Instrumentation studies for plasma jet and hypersonic wind tunnel,

"This research was supported by the McDonnell Aircraft Corporation under Contract no. 6140-20 P.O. 7S4899-R."

A variable atmosphere hypersonic wind tunnel for similitude studies

Mode of access: Internet.

Molecular identification and localization of filamentous symbiotic bacteria associated with the hydrothermal vent annelid Alvinella pompejana

Alvinella pompejana is a polychaetous annelid that inhabits high temperature environments associated with active deep-sea hydrothermal vents along the East Pacific Rise. A unique and diverse epibiotic microflora with a prominent filamentous morphotype is found associated with the worm's dorsal integument. A previous study established the taxonomic positions of two epsilon proteobacterial phylotypes, 13B and 5A, which dominated a clone library of 16S rRNA genes amplified by PCR from the epibiotic microbial community of an A. pompejana specimen. In the present study deoxyoligonucleotide PCR primers specific for phylotypes 13B and 5A were used to demonstrate that these phylotypes are regular features of the bacterial community associated with A. pompejana. Assaying of other surfaces around colonies of A. pompejana revealed that phylotypes 13B and 5A are not restricted to A. pompejana. Phylotype 13B occurs on the exterior surfaces of other invertebrate genera and rock surfaces, and phylotype 5A occurs on a congener, Alvinella caudata. The 13B and 5A phylotypes were identified and localized on A. pompejana by in situ hybridization, demonstrating that these two phylotypes are, in fact, the prominent filamentous bacteria on the dorsal integument of A. pompejana. These findings indicate that the filamentous bacterial symbionts of A. pompejana are epsilon Proteobacteria which do not have an obligate requirement for A. pompejana.

Hydrothermal-vent alvinellid polychaete dispersal in the eastern Pacific .1. Influence of vent site distribution, bottom currents, and biological patterns

Deep-sea hydrothermal-vent habitats are typically linear, discontinuous, and short-lived. Some of the vent fauna such as the endemic polychaete family Alvinellidae are thought to lack a planktotrophic larval stage and therefore not to broadcast-release their offspring. The genetic evidence points to exchanges on a scale that seems to contradict this type of reproductive pattern. However, the rift valley may topographically rectify the bottom currents, thereby facilitating the dispersal of propagules between active vent sites separated in some cases by 10s of kilometers or more along the ridge axis. A propagule flux model based on a matrix of intersite distances, long-term current-meter data, and information on the biology and ecology of Alvinellidae was developed to test this hypothesis. Calculations of the number of migrants exchanged between two populations per generation (N-m) allowed comparisons with estimates obtained from genetic studies. N, displays a logarithmic decrease with increasing dispersal duration and reaches the critical value of 1 after 8 d when the propagule Aux model was run in standard conditions. At most, propagule traveling time cannot reasonably exceed 15-30 d, according to the model, whereas reported distances between sites would require longer lasting dispersal abilities. Two nonexclusive explanations are proposed. First, some aspects of the biology of Alvinellidae have been overlooked and long-distance dispersal does occur. Second, such dispersal never occurs in Alvinellidae, but the spatial-temporal dynamics of vent sites over geological timescales allows short-range dispersal processes to maintain gene flow.

Lipid and lipid carbon stable isotope composition of the hydrothermal vent shrimp Mirocaris fortunata: evidence for nutritional dependence on photosynthetically fixed carbon

Mirocaris fortunata were sampled from the Lucky Strike hydrothermal vent area (Eiffel Tower site) on the mid-Atlantic ridge during the French DIVA 2 cruise (June 1994). Small adults (17 to 22 mm total length), although morphologically identical, could be divided into 2 categories on the basis of pigmentation, lipid composition and C-13/C-12 stable isotope ratios of fatty acids. Highly pigmented small adults (8.6 to 9.2 mu g carotenoid shrimp(-1)) contained higher levels of total lipid than similar-sized individuals containing lower levels of pigment (0.9 to 2.9 mu g carotenoid shrimp(-1)). Lipid class analysis indicated that wax esters comprised 62.5% of total lipid in the former group. These pigmented shrimp also contained high proportions of polyunsaturated fatty acids (PUFA), particularly the phototrophic microplanktonic markers 20:5(n-3) and 22:6(n-3) (14.0 and 33.5% respectively). By contrast small adults (22 mm) and adult shrimp (25 to 26 mm) with low levels of carotenoid pigmentation contained lower amounts of total lipid, little or no wax ester and low levels of 20:5(n-3) and 22:6(n-3), but did contain 16:2(n-4) and 18:2(n-4) and the non-methylene interrupted dienes 20:2 Delta 5,13 and 22:2 Delta 7,15. GC-IRMS analysis of all fatty acids and fatty alcohols in the pigmented small adults indicated delta(13)C values of -18.2 to -27.7 parts per thousand, which is consistent with a photosynthetic carbon source for these compounds. The C-13/C-12 isotope composition of fatty acids from low-pigmented small adults and adults was more variable (-12.5 to -33.1 parts per thousand) and suggests a bimodal distribution which may be attributable to differing nutritional sources or the physiological/reproductive status of these shrimp. Samples of eggs, which are carried by the female on the pleopods, represented approximately 57% of total somatic lipid which indicates a substantial reproductive investment by this species. The egg lipids comprised high proportions of triacylglycerols (64.4 to 78.0% of total lipid) whilst the fatty acid composition was dominated by the monounsaturated fatty acids 16:1(n-7), 18:1(n-7) and 18:1(n-9), which accounted for 65.7 to 33.5% of total fatty acids. By contrast, PUFA were relatively minor components of egg lipids, particularly 20:5(n-3) and 22:6(n-3), which accounted for only 1.1 and 2.9% of total egg fatty acids respectively. This indicates that the reproductive investment by this species is supported mainly by material derived from bacterial chemosynthesis. The potential for M. fortunata hedge betting by producing larvae which either metamorphose at the vent site or adopt a bathypelagic lifestyle and delay metamorphosis to facilitate more widespread dispersal is discussed.

Reducing Uncertainties in Estimation of Wind Effects on Tall Buildings Using Aerodynamic Wind Tunnel Tests

Tall buildings are wind-sensitive structures and could experience high wind-induced effects. Aerodynamic boundary layer wind tunnel testing has been the most commonly used method for estimating wind effects on tall buildings. Design wind effects on tall buildings are estimated through analytical processing of the data obtained from aerodynamic wind tunnel tests. Even though it is widely agreed that the data obtained from wind tunnel testing is fairly reliable the post-test analytical procedures are still argued to have remarkable uncertainties. This research work attempted to assess the uncertainties occurring at different stages of the post-test analytical procedures in detail and suggest improved techniques for reducing the uncertainties. Results of the study showed that traditionally used simplifying approximations, particularly in the frequency domain approach, could cause significant uncertainties in estimating aerodynamic wind-induced responses. Based on identified shortcomings, a more accurate dual aerodynamic data analysis framework which works in the frequency and time domains was developed. The comprehensive analysis framework allows estimating modal, resultant and peak values of various wind-induced responses of a tall building more accurately. Estimating design wind effects on tall buildings also requires synthesizing the wind tunnel data with local climatological data of the study site. A novel copula based approach was developed for accurately synthesizing aerodynamic and climatological data up on investigating the causes of significant uncertainties in currently used synthesizing techniques. Improvement of the new approach over the existing techniques was also illustrated with a case study on a 50 story building. At last, a practical dynamic optimization approach was suggested for tuning structural properties of tall buildings towards attaining optimum performance against wind loads with less number of design iterations.

Development of an ecotoxicological protocol for the deep-sea fauna using the hydrothermal vent shrimp Rimicaris exoculata

In light of deep-sea mining industry development, particularly interested in massive-sulphide deposits enriched in metals with high commercial value, efforts are increasing to better understand potential environmental impacts to local fauna. The aim of this study was to assess the natural background levels of biomarkers in the hydrothermal vent shrimp Rimicaris exoculata and their responses to copper exposure at in situ pressure (30MPa) as well as the effects of depressurization and pressurization of the high-pressure aquarium IPOCAMP. R. exoculata were collected from the chimney walls of the hydrothermal vent site TAG (Mid Atlantic Ridge) at 3630m depth during the BICOSE cruise in 2014. Tissue metal accumulation was quantified in different tissues (gills, hepatopancreas and muscle) and a battery of biomarkers was measured: metal exposure (metallothioneins), oxidative stress (catalase, superoxide dismutase, glutathione-S-transferase and glutathione peroxidase) and oxidative damage (lipid peroxidation). Data show a higher concentration of Cu in the hepatopancreas and a slight increase in the gills after incubations (for both exposed groups). Significant induction of metallothioneins was observed in the gills of shrimps exposed to 4μM of Cu compared to the control group. Moreover, activities of enzymes were detected for the in situ group, showing a background protection against metal toxicity. Results suggest that the proposed method, including a physiologically critical step of pressurizing and depressurizing the test chamber to enable the seawater exchange during exposure to contaminants, is not affecting metal accumulation and biomarkers response and may prove a useful method to assess toxicity of contaminants in deep-sea species.

Structural health of a road tunnel intersecting a large and active rockslide

This work presents the case of the San Lorenzo road tunnel, a transportation infrastructure located in the northern part of Italy, involved in the so-called Passo della Morte landslide. This tunnel crosses a large rockslide characterized by slow movements. Damages like water seepage inside the tunnel and concrete lining detachments have surfaced through the years, increasing the risk. This work develops the objective of tracing back the landslide-induced stresses directly responsible for the cracks’ pattern on the most damaged segments of the tunnel. The first section of this work gives information about the global framework: site geography and its strategic relevance, geological setting, hydrological and climate conditions will be provided. The road tunnel infrastructure and its interaction with the landslide phenomena will be discussed together with the active monitoring system, which has been working for more than 20 years. In the second part the several steps and tools used to add more details about the road damages are reported. A visualization of the actual state of the most damaged portions of the road has been reached. Then the attention has been addressed to the stresses acting on the road tunnel’s aforesaid portions, developing a FEM model of a section of the tunnel through a selected software. This latter process can be deemed as a beginning for further developments. Some preliminary results are shown to demonstrate the goodness of the assumptions made. The possible future set by this work aims at constant enlargement of information to be provided to the FEM software, and at the validation of the obtained results through the monitoring data interpretative tools.