Terrestrial structure-from-motion: spatial error analysis of roughness and morphology

Structure-from-Motion (SfM) photogrammetry is rapidly becoming a key tool for morphological characterisation and change detection of the earth surface. This paper demonstrates the use of Terrestrial Structure-from-Motion (TSfM) photogrammetry to acquire morphology and roughness data at the reach-scale in an upland gravel-bed river. We quantify 1) spatially-distributed error in TSfM derived Digital Elevation Models (DEMs) and 2) identify differences in roughness populations acquired from TSfM photogrammetry versus TLS. We identify an association between local topographic variation and error in the TSfM DEM. On flatter surfaces (e.g. bar and terrace surfaces), the difference between the TSfM and TLS DEMs are generally less than ±0.1 m. However, in areas of high topographic variability (>0.4 m) such as berm or terrace edges, differences between the TSfM and TLS DEMs can be up to ±1 m. Our results suggest that grain roughness estimates from the TSfM point cloud generate values twice those derived from the TLS point cloud on coarse berm areas, and up to four-fold those derived from the TLS point cloud over finer gravel bar surfaces. This finding has implications when using SfM data to derive roughness metrics for hydrodynamic modelling. Despite the use of standard filtering procedures, noise pertains in the SfM DEM and the time required for its reduction might partially outweigh the survey efficiency using SfM. Therefore, caution is needed when SfM surveys are employed for the assessment of surface roughness at a reach-scale

Milk production and composition, nitrogen utilization, and grazing behavior of late-lactation dairy cows as affected by time of allocation of a fresh strip of pasture

Eighty late-lactation dairy cows were used to examine the effects of allocating a new pasture strip of a sward based on ryegrass (Lolium perenne L.) in the morning (a.m.; ∼0730 h) or in the afternoon (p.m.; ∼1530 h) on milk production and composition, nitrogen (N) utilization, and grazing behavior. Cows grazed the same pasture strips for 24 h and were offered the same daily herbage allowance. Herbage composition differed among treatments; p.m. herbage had greater dry matter (DM; 22.7 vs. 19.9%), organic matter (OM; 89.5 vs. 88.9%), and water-soluble carbohydrate (10.9 vs. 7.6%) concentrations and lesser crude protein (20.5 vs. 22.2%) and neutral detergent fiber (48.8 vs. 50.4%) concentrations compared with a.m. herbage. Total fatty acids (FA), α-linolenic acid, and polyunsaturated FA (PUFA) were greater in a.m. herbage, whereas monounsaturated FA were greater in p.m. herbage. Estimates of herbage DM intake did not differ among treatments. Daily milk yields and milk fat and milk protein concentrations were similar among treatments, whereas milk fat (684 vs. 627 g/cow), milk protein (545 vs. 505 g/cow), and milk solids (milk fat + milk protein) yields (1,228 vs. 1,132 g/cow) tended to be greater for cows on p.m. herbage. Rumenic acid and total PUFA in milk were greater for cows on a.m. herbage, whereas oleic acid was greater for cows on p.m. herbage. Estimates of urinary N excretion (g/d) did not differ among treatments, but urinary N concentrations were greater for cows on a.m. herbage (5.85 vs. 5.36 g/L). Initial herbage mass (HM) available (kg of DM/ha) and instantaneous HM disappearance rates (kg of DM/ha and kg of DM/h) did not differ, but fractional disappearance rates (0.56 vs. 0.74 per hour for a.m. vs. p.m., respectively) differed. Under the current conditions, timing of pasture strip allocation altered the herbage nutrient supply to cows; allocating a fresh strip of pasture later in the day resulted in moderate increases in milk and milk solids yields in late-lactation dairy cows. Conversely, a greater concentration of precursor FA in a.m. herbage resulted in a greater concentration of beneficial FA in milk, compared with cows on p.m. herbage

Rôle du HLA dans la signalisation des cellules endothéliales en transplantation et contribution de HLA-E aux fonctions immunorégulatrices de l'endothélium

Mieux comprendre le rôle de l'endothélium dans la réponse immune et identifier de nouvelles cibles moléculaires pour le contrôle des dysfonctions endothéliales sont des enjeux majeurs pour combattre de nombreuses pathologies vasculaires et inflammatoires et le rejet de greffe en Transplantation. Les travaux réalisés au cours de ma thèse ont mis en évidence l'activation de GTPase RhoA dans les cellules endothéliales (CE) vasculaires consécutive à la liaison du HLA de classe I par les anticorps allospécifiques. Nous montrons le rôle central de RhoA dans un mécanisme à médiation immune de la prolifération endothéliale qui requiert la géranylgéranylation de RhoA et peut être inhibé par une statine. De façon complémentaire, nous montrons que la fixation d anticorps anti-HLA de classe II induit l apoptose des lymphocytes B mais pas des CE issues du même donneur et suggèrent que les CE échappent à l apoptose par l activation d une voie de survie impliquant la PI3-kinase. Enfin, par la mise en évidence de l expression des formes membranaire et soluble de HLA-E par les CE, nos travaux apportent la première description in vivo et in vitro de l expression et de la régulation de HLA-E par l endothélium. L ensemble de ces travaux montrent que, dans un contexte allogénique, l expression des molécules du HLA de classe I et de classe II par l endothélium contribue, via des voies de signalisation propres, à moduler les fonctions endothéliales telles que la prolifération et l apoptose. De plus, l expression de HLA-E procure de nouvelles fonctions immunorégulatrices aux CE et HLA-E soluble est un nouvel outil pour le diagnostic et l immunothérapie.The identification of new molecular targets to prevent endothelium dysfunction as well as a better understanding of the role of endothelium in the immune response are required to improve vascular injury and transplant outcome. The present study indicates that ligation of HLA class I and class II molecules on graft endothelial cells (EC) mediated by alloreactive anti-donor antibodies selectively activates signaling pathways affecting EC functions such as cell proliferation and apoptosis. Firstly, we showed that RhoA is a key mediator of signaling pathways leading to cytoskeleton reorganization and EC proliferation in response to HLA class I ligation and demonstrated the potent inhibitory effect of simvastatin on allostimulated EC growth. We also found that, in contrast to B cells, graft ECs escape from apoptosis mediated by HLA-DR ligation not as a result of moderate HLA-DR expression but rather as a result of specific signaling pathway involving the PI3-kinase. This study also demonstrated that EC express the non classical class I HLA-E molecules at the cell surface and release soluble HLA-E upon inflammation providing new immunoregulatory functions to EC and tools for diagnosis and immunotherapy.NANTES-BU Médecine pharmacie (441092101) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Temperature dependence of the protein resistance of poly- and oligo(ethylene glycol)-terminated alkanethiolate monolayers

Fourier transform infrared reflection absorption spectroscopy (FT-IRRAS) has been used to study the protein resistance of poly- and oligo(ethylene glycol) (PEG and OEG) terminated alkanethiolate self-assembled monolayers (SAMs) on Au and Ag in the temperature range from 0 to 85 °C. These experiments extend previous room-temperature studies by Harder et al.1 who related the protein adsorption characteristics of OEG-SAMs to the lateral density and corresponding molecular conformation of the ethylene glycol (EG) moieties in the film. In addition to the short oligomer OEG-SAMs, we investigated PEG-derivatized alkanethiolate monolayers with an average chain length of 45 EG units and a mean molecular mass of 2000 g/mol (PEG2000). We observe that films, which are protein resistant at room temperature, maintain their protein repulsive characteristics up to 85 °C but may adsorb significant amounts of protein if the temperature is lowered