Modelling spatial trends and local competition effects using semiparametric additive models

The aim of this project was to develop a joint approach to the estimation of spatial trends and competition effects in agricultural field trials. We chose to model the trend by means of a semi parametric model and to extend this class of models to include any number of smooth terms. Explicit expressions for the linear and smooth parts of the model are derived. Two approximations to the standard errors of the linear part are presented and compared. We discuss graphical methods for the initial identification of spatial structure in the data and propose more formal procedures to select the degree of smoothing and to test for the significance of treatment effects. We review the methodology already developed for competition models and improve the fitting procedure by calculating exact adjustments of the profile likelihood for a class of normal regression models. Classical competition models are extended to allow for the estimation of spatial trends via one or more linear smoothers. Methods to estimate the smoothing parameter in the presence of competition were derived. However, we have established that this approach needs to be extended to include correlated errors before it is complete. A mixed model approach to competition was also investigated. The analysis of the data from two agricultural trials grown at SCRI indicated that SAMs provide a flexible framework for identifying underlying trends in field trials. They generally improve precision of the treatment estimates and they enable spatial trends to be easily visualised. Competition between neighbouring plots was also identified

Emplacement of Cuban Ophiolites

According to their lithological and structural characteristics, three ophiolite bearing structural units are recognized in Cuba: 1) The Northern Ophiolitic Belt, a complex mélange that stretches more than 1000 km along the island; 2) The metamorphic basement of the Cretaceous Volcanic Arc Terrane; and 3) The tectonic slices in the high pressure metamorphic Escambray (Guamuhaya) Massif of south central Cuba. The available age constrains indicate that relics of oceanic lithosphere in Cuba are Late Mesozoic in age and probably originated in two different tectonic environments; 1) in a Late Jurassic- Neocomian small oceanic basin resulting from drifting between North America and a southern continent; and 2) in a suprasubduction marginal basin developed between the North American passive margin and an Aptian-Albian volcanic arc. Serpentinite slices and the high pressure amphibolites in the Mesozoic metasedimentary rocks of the Escambray (Guamuhaya) Massif originated during closure of a small oceanic basin, possibly during the Albian. The basement metamorphic rocks of the Volcanic Arc Terrane were derived from Upper Jurassic- Neocomian oceanic crust, metamorphosed during the development on this crust of a Middle Cretaceous volcanic arc. Ophiolites of the northern belt were probably derived from both the formerly mentioned small oceanic basin and suprasubduction marginal basin, and were emplaced in several episodes from the Campanian to the Middle Eocene. The different ophiolite types in Cuba represent relics of the oceanic lithosphere (the Proto-Caribbean oceanic basin) that developed between North and South America after the Pangea breakup. An alternative plate tectonic model is proposed and discussed

Optimal controller gains for inner current controllers in VSC inverters

The standard method for controlling an IGBT inverter (or any VSC inverter for that matter) is by vector current control. This control system consists of two cascaded control loops. One possible realisation of the outer controller is to control the DC bus voltage such that no more power is taken off the DC bus than is available. This creates a current reference, which is fed into the inner current controller. The inner current controller then regulates the current passing through the IGBT such that the desired power is dispatched onto the grid. Whilst most research treats the grid connection as a simple RL circuit, there is little consistency on the method by which the gains of the inner current controller are selected. Internal model control, modulus optimum and root locus methods are just a few of the methods used to find the gains. However, it is not clear which of these methods yields the best performance of the inner current controller. This work suggests that tuning on phase margin or manually tuning may not achieve the best results

Unifying thermodynamic and kinetic descriptions of single-molecule processes: RNA unfolding under tension

We use mesoscopic non-equilibrium thermodynamics theory to describe RNA unfolding under tension. The theory introduces reaction coordinates, characterizing a continuum of states for each bond in the molecule. The unfolding considered is so slow that one can assume local equilibrium in the space of the reaction coordinates. In the quasi-stationary limit of high sequential barriers, our theory yields the master equation of a recently proposed sequential-step model. Non-linear switching kinetics is found between open and closed states. Our theory unifies the thermodynamic and kinetic descriptions and offers a systematic procedure to characterize the dynamics of the unfolding processComment: 13 pages, 3 figure

CELL DEATH AND VIABILITY IN MARINE PHYTOPLANKTON

CITONATAplicación de ensayos in vitro para la detección precoz de ficotoxinas en muestras de poblaciones fitoplanctónicas multiespecífica

Entropy, non-ergodicity and non-Gaussian behaviour in ballistic transport

Ballistic transportation introduces new challenges in the thermodynamic properties of a gas of particles. For example, violation of mixing, ergodicity and of the fluctuation-dissipation theorem may occur, since all these processes are connected. In this work, we obtain results for all ranges of diffusion, i.e., both for subdiffusion and superdiffusion, where the bath is such that it gives origin to a colored noise. In this way we obtain the skewness and the non-Gaussian factor for the probability distribution function of the dynamical variable. We put particular emphasis on ballistic diffusion, and we demonstrate that in this case, although the second law of thermodynamics is preserved, the entropy does not reach a maximum and a non-Gaussian behavior occurs. This implies the non-applicability of the central limit theorem.Comment: 9 pages, 2 figure

Rose Bengal test: diagnostic yield and use for the rapid diagnosis of human brucellosis in emergency departments in endemic areas

ABSTRACTThe aim of the present study was to analyse the diagnostic yield of the rose Bengal test for the rapid diagnosis of human brucellosis in an emergency department in an area where the disease is endemic. The study included 711 patients diagnosed initially with brucellosis and 270 controls. Brucellosis patients were divided into three groups: group I, individuals with no regular exposure to or history of brucellosis; group II, individuals exposed repeatedly to Brucella infection; and group III, individuals infected with Brucella who had received appropriate treatment during the previous 12 months. Blood cultures were positive for 445 (62.6%) brucellosis patients, while the remaining 266 (37.4%) patients were diagnosed according to clinical and serological criteria. The overall sensitivity of the rose Bengal test was 92.9%. The specificities for groups I, II and III were 94.3%, 91.7% and 76.9%, respectively, with positive likelihood ratios of 16.5, 10.4 and 4.2, respectively. The diagnostic gain after the performance of the rose Bengal test was good or very good in patients with no previous exposure to Brucella or history of brucellosis, but poor in patients who were exposed repeatedly to Brucella or had a history of brucellosis and a low pre-test probability. Use of the rose Bengal test as the sole technique for the diagnosis of brucellosis in endemic areas should be considered very carefully in the context of patients who are exposed repeatedly to Brucella or have a history of brucellosis

Estudio fisiológico de Dinophysis spp. durante un ciclo de afloramiento/hundimiento en la Ría de Pontevedra

HABITFloraciones Algales Nocivas en Capas Fina

The record of a high-energy event in a mud entrapment on the inner shelf off the Guadiana river

Recent environmental changes associated with high-energy events and human impacts were investigated in a mud entrapment confined in the paleo-Guadiana incised valley. Those changes were recorded in a gravity core during the last 2500 years. An erosional event seems to have occurred at ca. 500 cal yr BP but it is not clear how much sediment was removed. This event was followed by an increase in river discharges until ca. 465 cal yr BP while the benthic foraminiferal faunas were dominated by species associated with shallow-water sandy sediments. Upward, sedimentological and benthic foraminiferal variations indicated environmental changes, promoted by variable sediment supplies to the shelf.info:eu-repo/semantics/publishedVersio

Paleoceanographic and climatic implications of a new Mediterranean Outflow branch in the southern Gulf of Cadiz

The presence of contourite drifts in the southern Gulf of Cadiz (GoC) along the Moroccan margin raises questions about the (re)circulation of Mediterranean Outflow Water (MOW) in the GoC and the origin of the currents depositing them. Here, we compare two cores representative of Iberian and Moroccan contourite drifts, covering the last 22 kyr. Although the whole sequence is contouritic in character, it reflects the interaction of distinctive silty-contourite facies (high flow velocity periods) imbedded in muddy-contourite facies (low flow velocity periods). Evidence from benthic foraminifera δ13C, sortable silt grain-size, oceanographic CTD profiles and numerical simulations, indicate the Mediterranean water mass as the source of the southern contourite deposits. Our data, therefore, suggests an additional branch of upper-MOW veering southwards off the Straits of Gibraltar along the Moroccan margin. During MIS-(Marine Isotope Stage) 2, upper-MOW was a sluggish current while in the Holocene upper-MOW dominated as a fast, semi-steady flow. Throughout the deglaciation, silty contourites associated with higher flow speeds were deposited in the northern and southern GoC during cold events such as Heinrich Stadial 1 (HS1) and the Younger Dryas, forced by global millennial-scale climate variability. Millennial variability also appears to drive the deposition of silty-contourites in the Holocene. We estimated an average duration of 1 ka for the process of depositing a fast contourite unit. The case of silty-contourite I6 (within HS1) allows us to illustrate with extremely high resolution a “rapid” sequential change in circulation, with gradual slow-down of dense Mediterranean water while surface was freshening (HS1), provoking injection of high-salinity intermediate waters (via contour-currents) into the GoC, and hence the North Atlantic. The subsequent brief collapse of dense water formation in the Mediterranean Sea triggered a major increase in sea surface temperatures (10 °C/ka) in the GoC, developing into the next interstadial (Bølling/Allerød). The impact of Mediterranean intermediate waters is manifested here by triggering a substantial rearrangement of intermediate and deep circulation in the North Atlantic, which would have further impacted the Atlantic Meridional Overturning Circulation (AMOC)