A high-precision liDAR-based method for surveying and classifying coastal notches

Formation of notches is an important process in the erosion of seaside cliffs. Monitoring of coastal notch erosion rate and processes has become a prime research focus for many coastal geomorphologists. Observation of notch erosion rate considers a number of characteristics, including cliff collapse risk, distinction of historical sea levels, and recognition of ongoing erosional mechanisms. This study presents new approaches for surveying and classifying marine notches based on a high-precision light detection and ranging (LiDAR)-based experiment performed on a small region of a coastal cliff in southern Portugal. A terrestrial LiDAR scanner was used to measure geometrical parameters and surface roughness of selected notches, enabling their classification according to shape and origin. The implemented methodology proved to be a highly effective tool for providing an unbiased analysis of marine morphodynamic processes acting on the seaside cliffs. In the analyzed population of voids carved into Miocene calcarenites in a coastal cliff section, two types of notch morphology were distinguished, namely U-shaped and V-shaped. The method presented here provides valuable data for landscape evaluation, sea-level changes, and any other types of analyses that rely on the accurate interpretation of cliff morphological features.National Science Centre [UMO-2015/17/D/ST10/02191

Spatio-temporal conjecture for diffusion

We present here a conjecture about the equivalence between the noise density of states of a system governed by a generalized Langevin equation and the fluctuation in the energy density of states in a Hamiltonian system. We present evidence of this for a disordered Heisenberg system.Comment: 6 pages, 1 figure. Submitted to Physica

On the use of spectral element methods for under-resolved simulations of transitional and turbulent flows

The present thesis comprises a sequence of studies that investigate the suitability of spectral element methods for model-free under-resolved computations of transitional and turbulent flows. More specifically, the continuous and the discontinuous Galerkin (i.e. CG and DG) methods have their performance assessed for under-resolved direct numerical simulations (uDNS) / implicit large eddy simulations (iLES). In these approaches, the governing equations of fluid motion are solved in unfiltered form, as in a typical direct numerical simulation, but the degrees of freedom employed are insufficient to capture all the turbulent scales. Numerical dissipation introduced by appropriate stabilisation techniques complements molecular viscosity in providing small-scale regularisation at very large Reynolds numbers. Added spectral vanishing viscosity (SVV) is considered for CG, while upwind dissipation is relied upon for DG-based computations. In both cases, the use of polynomial dealiasing strategies is assumed. Focus is given to the so-called eigensolution analysis framework, where numerical dispersion and diffusion errors are appraised in wavenumber/frequency space for simplified model problems, such as the one-dimensional linear advection equation. In the assessment of CG and DG, both temporal and spatial eigenanalyses are considered. While the former assumes periodic boundary conditions and is better suited for temporally evolving problems, the latter considers inflow / outflow type boundaries and should be favoured for spatially developing flows. Despite the simplicity of linear eigensolution analyses, surprisingly useful insights can be obtained from them and verified in actual turbulence problems. In fact, one of the most important contributions of this thesis is to highlight how linear eigenanalysis can be helpful in explaining why and how to use spectral element methods (particularly CG and DG) in uDNS/iLES approaches. Various aspects of solution quality and numerical stability are discussed by connecting observations from eigensolution analyses and under-resolved turbulence computations. First, DG’s temporal eigenanalysis is revisited and a simple criterion named "the 1% rule" is devised to estimate DG’s effective resolution power in spectral space. This criterion is shown to pinpoint the wavenumber beyond which a numerically induced dissipation range appears in the energy spectra of Burgers turbulence simulations in one dimension. Next, the temporal eigenanalysis of CG is discussed with and without SVV. A modified SVV operator based on DG’s upwind dissipation is proposed to enhance CG’s accuracy and robustness for uDNS / iLES. In the sequence, an extensive set of DG computations of the inviscid Taylor-Green vortex model problem is considered. These are used for the validation of the 1% rule in actual three-dimensional transitional / turbulent flows. The performance of various Riemann solvers is also discussed in this infinite Reynolds number scenario, with high quality solutions being achieved. Subsequently, the capabilities of CG for uDNS/iLES are tested through a complex turbulent boundary layer (periodic) test problem. While LES results of this test case are known to require sophisticated modelling and relatively fine grids, high-order CG approaches are shown to deliver surprisingly good quality with significantly less degrees of freedom, even without SVV. Finally, spatial eigenanalyses are conducted for DG and CG. Differences caused by upwinding levels and Riemann solvers are explored in the DG case, while robust SVV design is considered for CG, again by reference to DG’s upwind dissipation. These aspects are then tested in a two-dimensional test problem that mimics spatially developing grid turbulence. In summary, a point is made that uDNS/iLES approaches based on high-order spectral element methods, when properly stabilised, are very powerful tools for the computation of practically all types of transitional and turbulent flows. This capability is argued to stem essentially from their superior resolution power per degree of freedom and the absence of (often restrictive) modelling assumptions. Conscientious usage is however necessary as solution quality and numerical robustness may depend strongly on discretisation variables such as polynomial order, appropriate mesh spacing, Riemann solver, SVV parameters, dealiasing strategy and alternative stabilisation techniques.Open Acces

Threads and Or-Parallelism Unified

One of the main advantages of Logic Programming (LP) is that it provides an excellent framework for the parallel execution of programs. In this work we investigate novel techniques to efficiently exploit parallelism from real-world applications in low cost multi-core architectures. To achieve these goals, we revive and redesign the YapOr system to exploit or-parallelism based on a multi-threaded implementation. Our new approach takes full advantage of the state-of-the-art fast and optimized YAP Prolog engine and shares the underlying execution environment, scheduler and most of the data structures used to support YapOr's model. Initial experiments with our new approach consistently achieve almost linear speedups for most of the applications, proving itself as a good alternative for exploiting implicit parallelism in the currently available low cost multi-core architectures.Comment: 17 pages, 21 figures, International Conference on Logic Programming (ICLP 2010

Improving communication skill training in patient centered medical practice for enhancing rational use of laboratory tests: The core of bioinformation for leveraging stakeholder engagement in regulatory science.

Requests for laboratory tests are among the most relevant additional tools used by physicians as part of patient's health problemsolving. However, the overestimation of complementary investigation may be linked to less reflective medical practice as a consequence of a poor physician-patient communication, and may impair patient-centered care. This scenario is likely to result from reduced consultation time, and a clinical model focused on the disease. We propose a new medical intervention program that specifically targets improving the patient-centered communication of laboratory tests results, the core of bioinformation in health care. Expectations are that medical students training in communication skills significantly improve physicians-patient relationship, reduce inappropriate use of laboratorial tests, and raise stakeholder engagement

Dissipative maps at the chaos threshold: Numerical results for the single-site map

We numerically study, at the edge of chaos, the behaviour of the sibgle-site map $x_{t+1}=x_t-x_t/(x_t^2+\gamma^2)$, where $\gamma$ is the map parameter.Comment: 8 pages with 4 figures, submitted to Physica

La constitucionalización del Derecho y el régimen jurídico-administrativo

El presente estudio investiga en qué medida el fenómeno de la constitucionalización del Derecho administrativo promueve una relectura de los principios fundamentales de la materia desde la óptica de la Constitución, ayudando a la reestructuración dogmática del papel central ocupado por el hombre en el ordenamiento jurídico y de la dimensión material de la democracia, con una modificación sustancial de la relación entre Administración y administrado.This study researches to what extent the phenomenon of constitutionalization of administrative law promotes a re-reading of the fundamental principies of the matter from the perspective of the Constitution, helping to dogmatically restructure the central role occupied by individuals in the legal system and the material dimension of democracy, with a substantial change in the relationship between administration and administered

Cost-utility analysis of imaging for surveillance and diagnosis of hepatocellular carcinoma

Le carcinome hépatocellulaire (CHC) est une complication sérieuse associée aux maladies hépatiques chroniques. Les lignes directrices actuelles recommandent la surveillance du CHC par échographie tous les six mois. Cependant, la surveillance par échographie peut être difficile chez certains patients, notamment ceux atteints de cirrhose ou d'obésité. Autrement, la tomodensitométrie (TDM), l'imagerie par résonance magnétique (IRM) et l'IRM abrégée ont été explorées comme techniques d'imagerie alternatives et peuvent être utilisées chez les patients qui sont susceptibles d’avoir une échographie techniquement inadéquate. L’objectif de ce mémoire est d’évaluer l’impact économique de différentes stratégies de dépistage et de diagnostic basées sur l'imagerie chez des patients à risque de CHC, tout en tenant compte d'examens techniquement inadéquats et du taux de compliance des patients au programme de dépistage. Nous avons comparé sept stratégies de dépistage et diagnostic: stratégie A, échographie pour le dépistage et TDM pour le diagnostic; stratégie B, échographie pour le dépistage et IRM pour le diagnostic; stratégie C, échographie pour le dépistage et TDM pour une surveillance inadéquate ou positive; stratégie D, échographie pour le dépistage et IRM pour un dépistage inadéquat ou positif; stratégie E, dépistage et diagnostic par TDM suivis par une IRM en cas de dépistage inadéquat; stratégie F, dépistage et diagnostic avec IRM suivis par TDM pour un dépistage inadéquat; et stratégie G, dépistage avec IRM abrégée suivi par TDM pour un dépistage inadéquat ou IRM pour un dépistage positif. Deux scénarios de compliance au programme de surveillance ont été évalués: optimal et conservateur. Pour chaque scénario, la stratégie la plus coût-efficace reposait sur un seuil de propension à payer de Can$50,000 (dollars Canadiens) par année de vie ajustée en fonction de la qualité (AVAQ). Nous avons également effectué des analyses de sensibilité. Nos résultats ont démontré que la stratégie E était la stratégie la plus coût-efficace dans le scénario de compliance optimal (Can$13,631/AVAQ). Cependant, dans le scénario conservateur, la stratégie G constituait l'alternative la plus coût-efficace pour remplacer la pratique actuelle de surveillance par échographie (Can$39,681/AVAQ). Les analyses de sensibilité ont confirmé l'analyse de base dans le scénario de compliance optimal. Par contre, plusieurs paramètres ont modifié le rapport de coût-efficacité dans le scénario d’observance conservateur. En effectuant cette analyse économique, nous avons conclu qu'une approche individuelle, tenant compte des particularités cliniques des patients, est plus coût-efficace que la stratégie actuelle uniforme. Cependant, avant de mettre en place un programme de surveillance incorporant des modalités d'imagerie autres que l'échographie, les futures études devraient se concentrer sur le fardeau économique associé aux diagnostics faux positifs du CHC et sur la performance diagnostique d'examens d'IRM abrégés dans le scénario de surveillance.Hepatocellular carcinoma (HCC) is a serious complication associated with chronic liver disease. Current guidelines recommended HCC surveillance using ultrasound (US) every six months. However, US surveillance can be challenging for some patients, particularly those with cirrhosis or obesity. Alternately, computed tomography (CT), magnetic resonance imaging (MRI), and abbreviated MRI have been explored as alternative imaging modalities and may be used in selected patients who are likely to have experienced inadequate US examinations. In this thesis, we aimed to assess the cost-effectiveness of imaging-based surveillance and diagnostic strategies in patients at risk of HCC while taking into account technically inadequate examinations and patients’ compliance. We compared seven surveillance and diagnostic strategies: strategy A, US for surveillance and CT for diagnosis; strategy B, US for surveillance and MRI for diagnosis; strategy C, US for surveillance and CT for inadequate or positive surveillance; strategy D, US for surveillance and MRI for inadequate or positive surveillance; strategy E, surveillance and diagnosis with CT followed by MRI for inadequate surveillance; strategy F, surveillance and diagnosis with MRI followed by CT for inadequate surveillance; and strategy G, surveillance with abbreviated MRI followed by CT for inadequate surveillance or MRI for positive surveillance. Two compliance scenarios were evaluated: optimal and conservative. For each scenario, the most cost-effective strategy was based on a willingness-to-pay threshold of Can$50,000 (Canadian dollars) per quality-adjusted life year (QALY). We also performed sensitivity analyses. Our results demonstrated that strategy E was the most cost-effective strategy in scenarios with optimal patient compliance (Can$13,631/QALY). However, in scenarios with low patient compliance, strategy G was the most cost-effective alternative to the current US-surveillance practice (Can$39,681/QALY). Sensitivity analyses supported the base-case analysis in the optimal compliance scenario; however, several parameters altered the cost-effectiveness relationship in the conservative compliance scenario. By performing this economic analysis, we concluded that an individual approach, considering the clinical particularities of the patients, is more cost-effective than the current “one-size-fits-all” strategy. However, before implementing a surveillance program incorporating imaging modalities other than US, future studies should address the economic burden associated with false-positive HCC diagnoses and the accuracy of abbreviated MRI examinations in a surveillance setting