Trajectory Synthesis for Fisher Information Maximization

Estimation of model parameters in a dynamic system can be significantly improved with the choice of experimental trajectory. For general, nonlinear dynamic systems, finding globally "best" trajectories is typically not feasible; however, given an initial estimate of the model parameters and an initial trajectory, we present a continuous-time optimization method that produces a locally optimal trajectory for parameter estimation in the presence of measurement noise. The optimization algorithm is formulated to find system trajectories that improve a norm on the Fisher information matrix. A double-pendulum cart apparatus is used to numerically and experimentally validate this technique. In simulation, the optimized trajectory increases the minimum eigenvalue of the Fisher information matrix by three orders of magnitude compared to the initial trajectory. Experimental results show that this optimized trajectory translates to an order of magnitude improvement in the parameter estimate error in practice.Comment: 12 page

Learning Users’ Interests in a Market-Based Recommender System

Recommender systems are widely used to cope with the problem of information overload and, consequently, many recommendation methods have been developed. However, no one technique is best for all users in all situations. To combat this, we have previously developed a market-based recommender system that allows multiple agents (each representing a different recommendation method or system) to compete with one another to present their best recommendations to the user. Our marketplace thus coordinates multiple recommender agents and ensures only the best recommendations are presented. To do this effectively, however, each agent needs to learn the users’ interests and adapt its recommending behaviour accordingly. To this end, in this paper, we develop a reinforcement learning and Boltzmann exploration strategy that the recommender agents can use for these tasks. We then demonstrate that this strategy helps the agents to effectively obtain information about the users’ interests which, in turn, speeds up the market convergence and enables the system to rapidly highlight the best recommendations

Hemangioendotelioma multicéntrico de muñeca

Se presenta el caso de un hemangioendotelioma multicéntrico grado I localizado en el extremo distal del cúbito y en varios huesos del carpo en un varón de 57 años como hallazgo casual en un estudio radiográfico realizado tras un traumatismo de muñeca. El paciente fue tratado mediante resección amplia del extremo distal del cúbito y de los huesos del carpo afectos (ganchoso, piramidal y pisiforme) y artrodesis radiocarpiana con injerto autólogo tricortical de cresta ilíaca. Tras un seguimiento de 24 meses el paciente está asintomático y no presenta recidivas locales ni metástasis a distancia.A case of multicentric hemangioendothelioma located at the distal ulnar and different carpal bones was found in a 57-year-old man after a Rx control because a wrist trauma. The patient was treated by wide resection of distal ulnar and the affected carpal bones. Fusion of the radiocarpal joint was performed using tricortical autologous bone graft taken from the iliac crest. After 24-month follow-up, the patient was asymptomatic without local recurrence or metastasis

(How) Do research and administrative duties affect university professors’ teaching?

We analyze the interaction between university professors’ teaching quality and their research and administrative activities. Our sample is a high-quality individual panel data set from a medium size public Spanish university that allows us to avoid several types of biases frequently encountered in the literature. Although researchers teach roughly 20% more than non-researchers, their teaching quality is also 20% higher. Instructors with no research are 5 times more likely than the rest to be among the worst teachers. Over much of the relevant range, we find a nonlinear and positive relationship between research output and teaching quantity on teaching quality. Our conclusions may be useful for decision makers in universities and governments

Presència i distribució espacial de concentracions anormals d'ió nitrat a les aigües subterrànies dels aqüífers del Baix Fluvià (Alt Empordà)

Presentem una caracterització de la distribució espacial de la contaminació per nitrats en els aqüífers de la plana del baix Fluvià. En concret, els valors de concentració més elevats s’han observat a l’aqüífer superficial, on sobrepassen, amb escreix, els límits de potabilitat aconsellats pel RD 1138/1990. L’àrea més afectada ocupa part dels termes municipals de Vilamacolum i Torroella de Fluvià, en els quals hi predominen concentracions que oscil·len entre 50 i 200 mg × L–1. Els focus de contaminació són de tipus puntual i difús. Documentada la presència anormal de nitrats en aquest aqüífer, es planteja el correcte maneig agrícola, en vistes a una doble finalitat: d’una banda, contribuir a la planificació d’unes bones pràctiques agrícoles tenint en compte la relació entre volums de reg i aportacions de nitrogen; d’altra banda, preveure una progressiva recuperació de la qualitat de l’aqüífer, a partir de l’ús de tecnologies que integrin la ubicació d’unes zones favorables on es pugui maximitzar l’extracció del recurs contaminat, i la ubicació d’uns sòls aptes per a l’aplicació d’aquest recurs, amb uns criteris agronòmics coherents.Presentamos una caracterización de la distribución espacial de la contaminación por nitratos en los acuíferos de la llanura del baix Fluvià. En concreto, los valores de concentración más elevados se han observado en el acuífero superficial, donde sobrepasan, con creces, los límites de potabilidad aconsejados por el RD 1138/1990. El área más afectada ocupa parte de los términos municipales de Vilamacolum y Torroella de Fluvià, en los cuales predominan concentraciones que oscilan entre 50 y 200 mg × L–1. Los focos de contaminación son de tipo puntual y difuso. Documentada la presencia anormal de nitratos en este acuífero, se plantea el correcto manejo agrícola, en vistas a una doble finalidad: por un lado, contribuir a la planificación de unas buenas prácticas agrícolas teniendo en cuenta la relación entre volúmenes de riego y aportaciones de nitrógeno; por otro lado, prever una progresiva recuperación de la calidad del acuífero, a partir de usar tecnologías que integren la ubicación de unas zonas favorables donde se pueda maximizar la extracción del recurso contaminado, y la ubicación de unos suelos aptos para la aplicación de este recurso, con unos criterios agronómicos coherentes.A characterisation of spatial distribution of the nitrate groundwater contamination in the baix Fluvià plain is presented. Specially, the highest values have been found in the upper aquifer, where the critical values specified by RD 1138/1990 for drinking water are clearly surpassed in some cases. The worse afeected areas are the municipalities of Vilamacolum and Torroella de Fluvià where concentrations between 50 and 200 meq × l–1 are dominant. The contamination comes from both point and non-point sources. After documenting the abnormal amounts of nitrate in such aquifer the next issue is good agricultural management. This has two aims. Firstly, to contribute to the planning of good agricultural practices taking the relationship between amount of irrigation water and inputs of nitrogen into account. Secondly, to try to recover the aquifer progressively using technologies capable of integrating the setting of favourable areas where the polluted resource could be withdranw and other spots where there are soils suitable for the application of such resource, all with coherent agronomic criteria

Proprotein convertase subtilisin/kexin type 9 inhibitors in secondary prevention of vascular events in patients with stroke: consensus document and practice guidance

Introducción: Los pacientes, tras un ictus o un ataque isquémico transitorio, presentan un riesgo muy elevado de sufrir nuevos episodios vasculares. La reducción del nivel de colesterol unido a lipoproteínas de baja densidad (cLDL) reduce la incidencia de nuevos episodios, si bien una proporción importante de pacientes no alcanza los objetivos terapéuticos recomendados con los tratamientos hipolipemiantes actuales. El objetivo de este documento de consenso es actualizar el papel de los inhibidores de la proproteína convertasa subtilisina/kexina tipo 9 (iPCSK9; alirocumab y evolocumab) en la prevención secundaria de episodios vasculares en pacientes con ictus isquémico previo. Métodos: Se realizó una revisión bibliográfica para identificar las principales evidencias sobre el uso de iPCSK9 en estos pacientes y los objetivos terapéuticos recomendados de cLDL. Los resultados se discutieron en 2 reuniones de consenso, que constituyeron la base para la elaboración del documento. Conclusiones: Los iPSCSK9 son eficaces en la reducción del riesgo vascular en prevención secundaria y, específicamente, evolocumab ha demostrado esta reducción en pacientes con ictus isquémico previo. Ambos fármacos han demostrado un buen perfil de seguridad, incluso en pacientes que alcanzaron un nivel de cLDL <20?mg/dL. En este sentido, en el subestudio de episodios neurocognitivos con evolocumab no se observó ninguna señal de empeoramiento de la función cognitiva en pacientes con nivel muy bajo de cLDL. Con base en estas evidencias, en el documento se presentan recomendaciones prácticas sobre el uso de iPCSK9 para la prevención secundaria y seguimiento de episodios vasculares en pacientes con ictus isquémico previo.Introduction: Patients with history of stroke or transient ischaemic attack present considerable risk of future vascular events. Reducing levels of low-density lipoprotein (LDL) cholesterol decreases the incidence of new vascular events, although in a substantial number of patients, the currently available lipid-lowering therapies fail to achieve the therapeutic goals recommended in clinical guidelines. The aim of this consensus statement is to provide updated information on the role of the proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors alirocumab and evolocumab in the secondary prevention of vascular events in patients with history of ischaemic stroke. Methods: A literature review was performed to identify the main evidence on the use of PCSK9 inhibitors in these patients and the recommended therapeutic targets of LDL cholesterol. The results were discussed in 2 consensus meetings that constituted the basis for the drafting of the document. Conclusions: PCSK9 inhibitors are effective in reducing vascular risk in secondary prevention; evolocumab specifically has achieved this reduction in patients with history of ischaemic stroke. Moreover, both alirocumab and evolocumab present good safety profiles, even in patients achieving LDL cholesterol levels < 20 mg/dL, and no signs of cognitive impairment have been observed in patients treated with evolocumab who achieved very low levels of LDL cholesterol. In the light of this evidence, we provide practical recommendations about the use of PCSK9 inhibitors in secondary prevention of vascular events in patients with history of ischaemic stroke and follow-up of these patients.Los autores agradecen el apoyo recibido por parte de Amgen SA para la realización de este proyecto y a Ogilvy Health y Paula Martín Vaquero, PhD, por el apoyo metodológico y la asistencia editorial y de redacción médica para la elaboración de este documento de consenso

Tree-Based Methods for Discovery of Association between Flow Cytometry Data and Clinical Endpoints

We demonstrate the application and comparative interpretations of three tree-based algorithms for the analysis of data arising from flow cytometry: classification and regression trees (CARTs), random forests (RFs), and logic regression (LR). Specifically, we consider the question of what best predicts CD4 T-cell recovery in HIV-1 infected persons starting antiretroviral therapy with CD4 count between 200 and 350 cell/μL. A comparison to a more standard contingency table analysis is provided. While contingency table analysis and RFs provide information on the importance of each potential predictor variable, CART and LR offer additional insight into the combinations of variables that together are predictive of the outcome. In all cases considered, baseline CD3-DR-CD56+CD16+ emerges as an important predictor variable, while the tree-based approaches identify additional variables as potentially informative. Application of tree-based methods to our data suggests that a combination of baseline immune activation states, with emphasis on CD8 T-cell activation, may be a better predictor than any single T-cell/innate cell subset analyzed. Taken together, we show that tree-based methods can be successfully applied to flow cytometry data to better inform and discover associations that may not emerge in the context of a univariate analysis

A novel algorithm for dynamic student profile adaptation based on learning styles

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.E-learning recommendation systems are used to enhance student performance and knowledge by providing tailor- made services based on the students’ preferences and learning styles, which are typically stored in student profiles. For such systems to remain effective, the profiles need to be able to adapt and reflect the students’ changing behaviour. In this paper, we introduce new algorithms that are designed to track student learning behaviour patterns, capture their learning styles, and maintain dynamic student profiles within a recommendation system (RS). This paper also proposes a new method to extract features that characterise student behaviour to identify students’ learning styles with respect to the Felder-Silverman learning style model (FSLSM). In order to test the efficiency of the proposed algorithm, we present a series of experiments that use a dataset of real students to demonstrate how our proposed algorithm can effectively model a dynamic student profile and adapt to different student learning behaviour. The results revealed that the students could effectively increase their learning efficiency and quality for the courses when the learning styles are identified, and proper recommendations are made by using our method