MASS NESTING IN OLIVE RIDLEY SEA TURTLES: TIMING, NEARSHORE BEHAVIOR, AND POSSIBLE CUES FOR NESTING SYNCHRONIZATION

During the mass-nesting of sea turtles (also known as arribadas), thousands of turtles emerge from the ocean to nest simultaneously along a small stretch of beach. The research presented here involves a series of studies to describe the mass-nesting behavior and investigate possible mechanisms for synchronization of nesting. As a first step towards investigating this behavior and whether environmental cues might coordinate nesting, ten years of mass-nesting data were analyzed. Patterns in the behavior were described and statistical models were used to identify environmental variables that influence the onset and size of mass-nesting events. Findings suggest that the onset of synchronized nesting in olive ridley turtles is not triggered by a single environmental cue. Instead, events are likely affected by multiple physiological and environmental variables. In principle, behavioral interactions in the ocean might also play a role in the synchronization of nesting. A drone was used to conduct aerial surveys over the nearshore waters of a mass-nesting site during seven events to observe aggregations of turtles. No clear organization of turtles appeared to occur at sea, although in some cases turtles seem to move gradually shoreward prior to the onset of nesting. Findings reveal considerable variation among individual arribadas, with no universal pattern of group movement reliably preceding group emergence on the beach. A pheromone, or other chemical signal, could also serve as a cue to initiate the mass-nesting behavior. To test whether olfaction plays a role in the timing of nesting, I temporarily disrupted olfaction in olive ridley turtles to determine whether this impairment altered the timing of nesting during a mass-nesting event. Turtles captured at sea before an arribada, treated with an olfactory anesthetic, and released offshore nested significantly later than control turtles treated with saline. The results are consistent with the possibility that olfactory cues play a role in synchronizing nesting, although alternative explanations including effects on navigation or health cannot be excluded. Taken together, these findings provide insight into the possible mechanisms for synchronized nesting in sea turtles and have important implications for conservation management at this and other mass-nesting sites.Doctor of Philosoph

Somalie

Daraasaad la sameeyey 1966 oo ku saabsan sidii ay ku suurtaggeli lahayd warshadaynta dalka Soomaaliya iyo diraasaad dhaqaale oo halkaas lagu qoondaynayo mashaariic.Studio sulle possibilità di industrializzazione della Somalia effettuato nel 1966 e studio economico dei progetti in essere.A study on the possibilities of industrialization of Somalia carried out in 1966 and an economic study of the projects in place.Link:http://aei.pitt.edu/34949/1/A1100.pd

Quantifying Nearshore Sea Turtle Densities: Applications of Unmanned Aerial Systems for Population Assessments

Although sea turtles face significant pressure from human activities, some populations are recovering due to conservation programs, bans on the trade of turtle products, and reductions in bycatch. While these trends are encouraging, the status of many populations remains unknown and scientific monitoring is needed to inform conservation and management decisions. To address these gaps, this study presents methods for using unmanned aerial systems (UAS) to conduct population assessments. Using a fixed-wing UAS and a modified strip-transect method, we conducted aerial surveys along a three-kilometer track line at Ostional, Costa Rica during a mass-nesting event of olive ridley turtles (Lepidochelys olivacea). We visually assessed images collected during six transects for sea turtle presence, resulting in 682 certain detections. A cumulative total of 1091 certain and probable turtles were detected in the collected imagery. Using these data, we calculate estimates of sea turtle density (km-2) in nearshore waters. After adjusting for both availability and perception biases, we developed a low-end estimate of 1299 ± 458 and a high-end estimate of 2086 ± 803 turtles per km-2. This pilot study illustrates how UAS can be used to conduct robust, safe, and cost-effective population assessments of sea turtle populations in coastal marine ecosystems

Classification of hepatic metastasis in enhanced CT images by dipolar decision tree

- Cette étude a pour but de réaliser une classification des métastases hépatiques, en imagerie scanner. Les régions d'intérêt analysées représentent du tissu sain, et quatre types de métastases. Pour chaque patient, trois acquisitions sont réalisées (sans injection de produit de contraste, aux phases artérielle et portale après injection). La méthode comporte une première étape de caractérisation par analyse de texture, suivie d'une classification des régions. La méthode de classification utilisée est basée sur les arbres de décision dipolaires. Dans cette méthode, chaque noeud de l'arbre correspond à un test multivariable (hyperplan). La recherche de l'hyperplan optimal est basée sur la séparation des dipôles (paire de vecteurs de paramètres de l'ensemble d'apprentissage). Les résultats préliminaires montrent que la qualité de classification augmente quand le temps d'acquisition des images est pris en compte, et qu'elle est supérieure à celle obtenue par d'autres méthodes de classification

Modélisation vasculaire 3D : vers une compréhension de la texture

L'analyse de texture des images médicales est souvent réalisée selon une approche « aveugle » qui présente l'avantage d'être générique, mais ne permet pas de donner une interprétation physiologique aux caractéristiques de texture mesurées. Nous proposons une démarche plus explicative, basée sur la modélisation d'un constituant important de tout organe, et qui participe, sous certaines conditions, de façon importante à la texture de l'image: la vascularisation. La modélisation de l'acquisition des images scanner permet d'étudier les relations entre les paramètres du modèle vasculaire, liés aux propriétés physiologiques de la vascularisation, et les caractéristiques de texture, ainsi que d'essayer de comprendre l'évolution de ces caractéristiques en fonction des conditions d'acquisition des images

Initial clinical validation of a hybrid in silico—in vitro cardiorespiratory simulator for comprehensive testing of mechanical circulatory support systems

Simulators are expected to assume a prominent role in the process of design—development and testing of cardiovascular medical devices. For this purpose, simulators should capture the complexity of human cardiorespiratory physiology in a realistic way. High fidelity simulations of pathophysiology do not only allow to test the medical device itself, but also to advance practically relevant monitoring and control features while the device acts under realistic conditions. We propose a physiologically controlled cardiorespiratory simulator developed in a mixed in silico-in vitro simulation environment. As inherent to this approach, most of the physiological model complexity is implemented in silico while the in vitro system acts as an interface to connect a medical device. As case scenarios, severe heart failure was modeled, at rest and at exercise and as medical device a left ventricular assist device (LVAD) was connected to the simulator. As initial validation, the simulator output was compared against clinical data from chronic heart failure patients supported by an LVAD, that underwent different levels of exercise tests with concomitant increase in LVAD speed. Simulations were conducted reproducing the same protocol as applied in patients, in terms of exercise intensity and related LVAD speed titration. Results show that the simulator allows to capture the principal parameters of the main adaptative cardiovascular and respiratory processes within the human body occurring from rest to exercise. The simulated functional interaction with the LVAD is comparable to the one clinically observed concerning ventricular unloading, cardiac output, and pump flow. Overall, the proposed simulation system offers a high fidelity in silico-in vitro representation of the human cardiorespiratory pathophysiology. It can be used as a test bench to comprehensively analyze the performance of physically connected medical devices simulating clinically realistic, critical scenarios, thus aiding in the future the development of physiologically responding, patient-adjustable medical devices. Further validation studies will be conducted to assess the performance of the simulator in other pathophysiological conditions

Couplage d'un modèle vasculaire bi-niveau et d'un modèle d'acquisition d'images : application à la simulation d'IRM dynamique du Carcinome Hépatocellulaire

La modélisation physiologique permet de mieux comprendre les images médicales et de mettre en évidence, dans l'image, des marqueurs de la pathologie. Dans cet article, nous proposons de coupler un modèle de la vascularisation hépatique à un modèle d'acquisition d'Images de - Résonance Magnétique (IRM), et d'appliquer ces modèles à la simulation d'IRM dynamique du Carcinome Hépatocellulaire (CHC). Le modèle vasculaire intègre les propriétés anatomiques et fonctionnelles clos vaisseaux, modifiées au cours du développement tumoral (densité vasculaire, débits, perméabilité, etc). Il permet de simuler la propagation de différents produits de contraste, ou tenant compte de leurs principales propriétés physiques et magnétiques, aux niveaux macro- et micro-vasculaire. Les images simulées à clos temps d'acquisition différents (phase artérielle, phase portale) présentent clos contrastes proches de ceux observés sur clos images réelles

Parthenogenesis In The Tropical Gekkonid Lizard, Nactus Arnouxii (Sauria: Gekkonidae)

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137400/1/evo02464.pd