Sea-ice habitat preference of the Pacific walrus (Odobenus rosmarus divergens) in the Bering Sea: a multiscaled approach

Thesis (M.S.) University of Alaska Fairbanks, 2015The goal of this thesis is to define specific parameters of mesoscale sea-ice seascapes for which walruses show preference during important periods of their natural history. This research thesis incorporates sea-ice geophysics, marine-mammal ecology, remote sensing, computer vision techniques, and traditional ecological knowledge of indigenous subsistence hunters in order to quantitatively study walrus preference of sea ice during the spring migration in the Bering Sea. Using an approach that applies seascape ecology, or landscape ecology to the marine environment, our goal is to define specific parameters of ice-patch descriptors and mesoscale seascapes in order to evaluate and describe potential walrus preference for such ice and the ecological services it provides during an important period of their life-cycle. The importance of specific sea-ice properties to walrus occupation motivates an investigation into how walruses use sea ice at multiple spatial scales when previous research suggests that walruses do not show preference for particular floes. Analysis of aerial imagery, using image processing techniques and digital geomorphometric measurements (floe size, shape, and arrangement), demonstrated that while a particular floe may not be preferred, at larger scales a collection of floes, specifically an ice-patch (< 4 km²), was preferred. This shows that walruses occupy ice patches with distinct ice features such as floe convexity, spatial density, and young ice and open water concentration. Ice patches that are occupied by adult and juvenile walruses show a small number of characteristics that vary from those ice patches that were visually unoccupied. Using synthetic aperture radar imagery, we analyzed co-located walrus observations and statistical texture analysis of radar imagery to quantify seascape preferences of walruses during the spring migration. At a coarse resolution of 100-9,000 km², seascape analysis shows that, for the years 2006-2008, walruses were preferentially occupying fragmented pack ice seascapes range 50-89% of the time, when, all throughout the Bering Sea, only range 41-46% of seascapes consisted of fragmented pack ice. Traditional knowledge of a walrus' use of sea ice is investigated through semi-directed interviews conducted with subsistence hunters and elders from Savoonga and Gambell, two Alaskan Native communities on St. Lawrence Island, Alaska. Informants were provided with a large nautical map of the land and ocean surrounding St. Lawrence Island and 45 printed largeformat aerial photographs of walruses on sea ice to stimulate discussion as questions were asked to direct the topics of conversation. Informants discussed change in sea ice conditions over time, walrus behaviors during the fall and spring subsistence hunts, and sea-ice characteristics that walruses typically occupy. These observations are compared with ice-patch preferences analyzed from aerial imagery. Floe size was found to agree with remotely-sensed ice-patch analysis results, while floe shape was not distinguishable to informants during the hunt. Ice-patch arrangement descriptors concentration and density generally agreed with ice-patch analysis results. Results include possible preference of ice-patch descriptors at the ice-patch scale and fragmented pack ice preference at the seascape scale. Traditional knowledge suggests large ice ridges are preferential sea-ice features at the ice-patch scale, which are rapidly becoming less common during the fall and spring migration of sea ice through the Bering Sea. Future work includes increased sophistication of the synthetic aperture radar classification algorithm, experimentation with various spatial scales to determine the optimal scale for walrus' life-cycle events, and incorporation of further traditional knowledge to investigate and interface crosscultural sea-ice observations, knowledge and science to determine sea ice importance to marine mammals in a changing Arctic

The Impact of Regulatory Changes on the Efficiency of the Phase II EU ETS European Carbon Futures

This study investigates long-horizon weak form market efficiency in the Phase II EU ETS (European Union Emissions Trading Scheme) Carbon Futures Market. Using data that encompasses exchange based (ECX) trades in Phase I and Phase II ECX CFI futures contracts from January 1, 2008, to September 28, 2010, this study employs various tests of long horizon weak form market efficiency including variance ratio tests, tests of trading rule profitability, and serial correlation. In contrast to prior research that focuses on Phase I EU ETS, this study finds evidence of a significant structural change to the EU ETS from Phase I to Phase II, and supports the efficient market hypothesis during Phase II (2008 “2010). Results suggest that documented improvements in market quality, increasing trading activity, and removal of Phase I market frictions have fostered improvements in market efficiency into and during Phase II

Howdah: Load Profiling via In-Band Flow Classification and P4

The challenges of managing datacenter traffic increase with the complexity and variety of new Internet and Web applications. Efficient network management systems are often required to thwart delays and minimize failures. In this regard, it appears helpful to identify in advance the different classes of flows that (co)exist in the network, characterizing them into different types according to the different latency/bandwidth requirements. In this paper, we propose Howdah, a traffic identification and profiling mechanism that uses Machine Learning and a congestion-aware forwarding strategy to offer adaptation to different traffic classes with the support of programmable data-planes. With Howdah, sender and gateway elements inject in-band traffic information obtained using supervised learning. When a switch or a router receives a packet, it exploits such host-based traffic classification to adapt to a desirable traffic profile, for example, balancing the load. We compare our solutions against recent traffic engineering solutions and show the efficacy of cooperation between host traffic classification and P4-based switch forwarding policies, reducing packet transmission time in datacenter scenarios

Deserts and pile-ups in the distribution of exoplanets due to photoevaporative disc clearing

We present models of giant planet migration in evolving protoplanetary discs. We show that disc clearing by EUV photoevaporation can have a strong effect on the distribution of giant planet semi-major axes. During disc clearing planet migration is slowed or accelerated in the region where photoevaporation opens a gap in the disc, resulting in "deserts" where few giant planets are found and corresponding "pile-ups" at smaller and larger radii. However, the precise locations and sizes of these features are strong functions of the efficiency of planetary accretion, and therefore also strongly dependent on planet mass. We suggest that photoevaporative disc clearing may be responsible for the pile-up of ~Jupiter-mass planets at ~1AU seen in exoplanet surveys, and show that observations of the distribution of exoplanet semi-major axes can be used to test models of both planet migration and disc clearing.Comment: 5 pages, 3 figures. Accepted for publication in MNRAS Letter

Evaluación de los riesgos potenciales en carreteras por carencia de señalizaciones y propuesta de solución para la carretera Quinua – San Francisco (km. 26+000 – km. 78+500)

El tramo vial materia de la investigación a realizar, se ubica al Noreste del Departamento de Ayacucho, entre las provincias de Huamanga y La Mar. En la actualidad, entre las progresivas km. 26 + 000 hasta el km. 78 + 500 con un total de 52.5 km, existe una carretera de dos vías pavimentadas de 7.5 m. de ancho de calzada, la misma que carece de señalización, siendo esta condición el problema que motiva la presente tesis. Para que una vía cumpla sus objetivos y principalmente con las normas de seguridad vial, se necesita que las señales viales sean ubicados convenientemente para que orientarán a los conductores en el logro de una mejor operatividad de sus vehículos y mediante ello, evitar accidentes. Las poblaciones de Quinua, Tambo y otras localidades de la zona han migrado a la localidad de San Francisco y otros lugares de la Amazonía de Ayacucho y como consecuencia de ello, por razones de intercambio de productos y/o servicios, se produce en esa ruta un continuo desplazamiento de personas, mediante los vehículos automotores. Es por esto que, según el Manual de Dispositivos de Control de Tránsito Automotor en Calles y Carreteras, lograremos colocar las señalizaciones donde sea conveniente y así ayude a mejorar la seguridad en el tránsito de la zona.Tesi

Slideflow: Deep Learning for Digital Histopathology with Real-Time Whole-Slide Visualization

Deep learning methods have emerged as powerful tools for analyzing histopathological images, but current methods are often specialized for specific domains and software environments, and few open-source options exist for deploying models in an interactive interface. Experimenting with different deep learning approaches typically requires switching software libraries and reprocessing data, reducing the feasibility and practicality of experimenting with new architectures. We developed a flexible deep learning library for histopathology called Slideflow, a package which supports a broad array of deep learning methods for digital pathology and includes a fast whole-slide interface for deploying trained models. Slideflow includes unique tools for whole-slide image data processing, efficient stain normalization and augmentation, weakly-supervised whole-slide classification, uncertainty quantification, feature generation, feature space analysis, and explainability. Whole-slide image processing is highly optimized, enabling whole-slide tile extraction at 40X magnification in 2.5 seconds per slide. The framework-agnostic data processing pipeline enables rapid experimentation with new methods built with either Tensorflow or PyTorch, and the graphical user interface supports real-time visualization of slides, predictions, heatmaps, and feature space characteristics on a variety of hardware devices, including ARM-based devices such as the Raspberry Pi

Cretaceous tetrapod tracks from Italy: a treasure trove of exceptional biodiversity

After about thirty years of investigation, the Cretaceous tetrapod track record from Italy has proved to be a ‘Rosetta Stone’ for improving understanding of the palaeogeographical and palaeoenvironmental evolution of the peri-Adriatic area. In the present contribution, we summarize current knowledge and diferent interpretations proposed on the basis of twelve ichnosites from northern, central and southern Italy. The tetrapod track record is represented by few ichnosites in the earliest Cretaceous, with the bulk of the record reported from carbonate platform deposits of the Aptian-Cenomanian interval and, in the Late Cretaceous, from a extensive-tracksite in Apulia preserving thousands of dinosaur footprints. On the whole, the ichnological diversity documented by the material indicates a high diversity of trackmakers, among which are sauropods, diferent kinds of theropods, ankylosaurs and hadrosaurs. The persistent occurrence of dinosaur footprints at diferent stratigraphic levels produced significant questions and constituted a dramatic constraint for the understanding of palaeogeographical and geodynamical evolution of the Mediterranean area during the Mesozoic, suggesting new and diferent interpretations that challenged previous reconstructions.Fil: Petti, Fabio Massimo. Museo Delle Scienze Di Trento; ItaliaFil: Antonelli, Mateo. Università di Roma; ItaliaFil: Citton, Paolo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; ArgentinaFil: Mariotti, Nino. Università di Roma; ItaliaFil: Petruzzelli, Marco. Università di Bari, Dipartimento di Scienze della Terra e Geoambientali; ItaliaFil: Pignatti, Johannes. Università di Roma; ItaliaFil: D’Orazi Porchetti, Simone. Università di Roma; ItaliaFil: Romano, Marco. Università di Roma; ItaliaFil: Sacchi, Eva. Università di Roma; ItaliaFil: Sacco, Enrico. Università di Roma; ItaliaFil: Wagensommer, Alexander. GRID (Gruppo di Ricerca sulle Impronte di Dinosauro), San Giovanni Rotondo; Itali

On the origin of [Ne II] emission in young stars: mid-infrared and optical observations with the Very Large Telescope

{Abridged version for ArXiv}. We provide direct constraints on the origin of the [Ne II] emission in 15 young stars using high-spatial and spectral resolution observations with VISIR at the VLT that allow us to study the kinematics of the emitting gas. In addition we compare the [Ne II] line with optical forbidden lines observed for three stars with UVES. The [Ne II] line was detected in 7 stars, among them the first confirmed detection of [Ne II] in a Herbig Be star, V892 Tau. In four cases, the large blueshifted lines indicate an origin in a jet. In two stars, the small shifts and asymmetric profiles indicate an origin in a photo-evaporative wind. CoKu Tau 1, seen close to edge-on, shows a spatially unresolved line centered at the stellar rest velocity, although cross-dispersion centroids move within 10 AU from one side of the star to the other as a function of wavelength. The line profile is symmetric with wings extending up to about +-80 km/s. The origin of the [Ne II] line could either be due to the bipolar jet or to the disk. For the stars with VLT-UVES observations, in several cases, the optical forbidden line profiles and shifts are very similar to the profile of the [Ne II] line, suggesting that the lines are emitted in the same region. A general trend observed with VISIR is a lower line flux when compared with the fluxes obtained with Spitzer. We found no correlation between the line full-width at half maximum and the line peak velocity. The [Ne II] line remains undetected in a large part of the sample, an indication that the emission detected with Spitzer in those stars is likely extended.Comment: Accepted for publication in Astronomy & Astrophysics; revised version: corrected minor typos, corrected center values (col 3) for CoKuTau1 in Table