Short-term sediment resuspension on the continental slope and geochemical implications: the Faeroe-Shetland Channel

Continental slopes are important and complex regions that connect shallow shelf seas with the deep ocean. Since a large part of the global primary productivity takes place on the continental margins, knowledge on sediment resuspension and associated processes on the continental slope is crucial to understand the fate of particles, including biogenic debris. The objectives of the study described in this thesis were to better understand the interactions between near-bottom currents and surface sediments of the continental slope, and to assess the impact of sediment resuspension on the cross-slope redistribution of biogenic and non-biogenic particles. While most of the studies conducted on sediment resuspension on continental margins have investigated the role of seasonal to inter-annual variations of the near-bottom currents, this thesis particularly focuses on short-term (tidal to sub-tidal) mechanisms. High-resolution studies have the potential to provide valuable information on the short-term processes involved in sediment resuspension, which, due to their difficulty to be resolved, have not received much attention, yet. The novel aspect of this work lies in the combination of fast sampling near-bottom sediment traps, turbidity sensors and current meters moored on a high-energy continental slope. Our data show that massive and abrupt sediment resuspension occurred at mid-slope and is associated with sudden drop of the temperature and upslope surge of the near-bottom currents. A more detailed study reveals that such massive resuspension was facilitated by strong vertical velocities generated at the leading edge of internal non-linear waves travelling up the slope. This finding suggests the importance of the interaction of such a phenomenon with the seabed can provide a potentially dominant mechanism for upward transport of sediment over continental slopes that may counteract downward avalanching of material by gravity. The results presented in this thesis show the importance of the short-term processes in the resuspension of sediment on the slope and in the transfer of biogenic materials from the shelf to the deep ocean. This transfer may have significant implications for organic matter recycling along the ocean margins. This work represents the first step towards a better understanding of these potentially very active processes. Clearly, further investigations are needed, particularly for the highly productive ocean margins such as areas with high continental input or coastal upwelling regions, which are also receiving much attention in terms of their paleo-climatological significance. Furthermore, high-energy processes (see Chapter 3) and the associated massive sediment transport and organic matter recycling (see Chapters 2, 4 and 5) may create major perturbations of the sedimentary signal and lead to erroneous interpretation of proxy data

Developing Intensity-Duration-Frequency (IDF) Curves From Satellite-Based Precipitation: Methodology and Evaluation

Given the continuous advancement in the retrieval of precipitation from satellites, it is important to develop methods that incorporate satellite-based precipitation data sets in the design and planning of infrastructure. This is because in many regions around the world, in situ rainfall observations are sparse and have insufficient record length. A handful of studies examined the use of satellite-based precipitation to develop intensity-duration-frequency (IDF) curves; however, they have mostly focused on small spatial domains and relied on combining satellite-based with ground-based precipitation data sets. In this study, we explore this issue by providing a methodological framework with the potential to be applied in ungauged regions. This framework is based on accounting for the characteristics of satellite-based precipitation products, namely, adjustment of bias and transformation of areal to point rainfall. The latter method is based on previous studies on the reverse transformation (point to areal) commonly used to obtain catchment-scale IDF curves. The paper proceeds by applying this framework to develop IDF curves over the contiguous United States (CONUS); the data set used is Precipitation Estimation from Remotely Sensed Information Using Artificial Neural Networks – Climate Data Record (PERSIANN-CDR). IDFs are then evaluated against National Oceanic and Atmospheric Administration (NOAA) Atlas 14 to provide a quantitative estimate of their accuracy. Results show that median errors are in the range of (17–22%), (6–12%), and (3–8%) for one-day, two-day and three-day IDFs, respectively, and return periods in the range (2–100) years. Furthermore, a considerable percentage of satellite-based IDFs lie within the confidence interval of NOAA Atlas 14

Hipertiroidismo felino : caso clínico

Tras efectuar una revisión bibliográfica centrada en el diagnóstico clínico y laboratorial del hipertiroidismo felino, así como en el tratamiento mediante antitiroideos orales, el presente artículo describe un caso de esta patología felina geriátrica todavía poco frecuente en España. Posteriormente se discuten aspectos importantes del diagnóstico y tratamiento.After a bibliographic update focused on clinical and laboratorial diagnosis of feline hiperthyroidism, as well on its oral treatment, this article describes one case of this geriatric unfrequent disease in Spain. Then, important diagnostic and treatment issues are discussed

Porosity measurements of interstellar ice mixtures using optical laser interference and extended effective medium approximations

Aims. This article aims to provide an alternative method of measuring the porosity of multi-phase composite ices from their refractive indices and of characterising how the abundance of a premixed contaminant (e.g., CO2) affects the porosity of water-rich ice mixtures during omni-directional deposition. Methods. We combine optical laser interference and extended effective medium approximations (EMAs) to measure the porosity of three astrophysically relevant ice mixtures: H2O:CO2=10:1, 4:1, and 2:1. Infrared spectroscopy is used as a benchmarking test of this new laboratory-based method. Results. By independently monitoring the O-H dangling modes of the different water-rich ice mixtures, we confirm the porosities predicted by the extended EMAs. We also demonstrate that CO2 premixed with water in the gas phase does not significantly affect the ice morphology during omni-directional deposition, as long as the physical conditions favourable to segregation are not reached. We propose a mechanism in which CO2 molecules diffuse on the surface of the growing ice sample prior to being incorporated into the bulk and then fill the pores partly or completely, depending on the relative abundance and the growth temperature.Comment: 9 pages, 6 figures, 1 table. Accepted for publication in A&

An analysis of interplanetary solar radio emissions associated with a coronal mass ejection

Coronal mass ejections (CMEs) are large-scale eruptions of magnetized plasma that may cause severe geomagnetic storms if Earth-directed. Here we report a rare instance with comprehensive in situ and remote sensing observa- tions of a CME combining white-light, radio, and plasma measurements from four different vantage points. For the first time, we have successfully applied a radio direction-finding technique to an interplanetary type II burst detected by two identical widely separated radio receivers. The derived locations of the type II and type III bursts are in general agreement with the white light CME recon- struction. We find that the radio emission arises from the flanks of the CME, and are most likely associated with the CME-driven shock. Our work demon- strates the complementarity between radio triangulation and 3D reconstruction techniques for space weather applications

Gene expression profiling reveals overexpression of TSPAN13 in prostate cancer.

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