State Estimation and Smoothing for the Probability Hypothesis Density Filter

Tracking multiple objects is a challenging problem for an automated system, with applications in many domains. Typically the system must be able to represent the posterior distribution of the state of the targets, using a recursive algorithm that takes information from noisy measurements. However, in many important cases the number of targets is also unknown, and has also to be estimated from data. The Probability Hypothesis Density (PHD) filter is an effective approach for this problem. The method uses a first-order moment approximation to develop a recursive algorithm for the optimal Bayesian filter. The PHD recursion can implemented in closed form in some restricted cases, and more generally using Sequential Monte Carlo (SMC) methods. The assumptions made in the PHD filter are appealing for computational reasons in real-time tracking implementations. These are only justifiable when the signal to noise ratio (SNR) of a single target is high enough that remediates the loss of information from the approximation. Although the original derivation of the PHD filter is based on functional expansions of belief-mass functions, it can also be developed by exploiting elementary constructions of Poisson processes. This thesis presents novel strategies for improving the Sequential Monte Carlo implementation of PHD filter using the point process approach. Firstly, we propose a post-processing state estimation step for the PHD filter, using Markov Chain Monte Carlo methods for mixture models. Secondly, we develop recursive Bayesian smoothing algorithms using the approximations of the filter backwards in time. The purpose of both strategies is to overcome the problems arising from the PHD filter assumptions. As a motivating example, we analyze the performance of the methods for the difficult problem of person tracking in crowded environment

The effect of water on the binding of glycosaminoglycan saccharides to hydroxyapatite surfaces: A molecular dynamics study

Classical molecular dynamics (MD) simulations have been employed to study the interaction of the saccharides glucuronic acid (GlcA) and N-acetylgalactosamine (GalNAc) with the (0001) and (011̄0) surfaces of the mineral hydroxyapatite (HAP). GlcA and GalNAc are the two constituent monosaccharides of the glycosaminoglycan chondroitin sulfate, which is commonly found in bone and cartilage and has been implicated in the modulation of the hydroxyapatite biomineralization process. MD simulations of the mineral surfaces and the saccharides in the presence of solvent water allowed the calculation of the adsorption energies of the saccharides on the HAP surfaces. The calculations show that GalNAc interacts with HAP principally through the sulfate and the carbonyl of acetyl amine groups, whereas the GlcA interacts primarily through the carboxylate functional groups. The mode and strength of the interaction depends on the orientation of the saccharide with respect to the surface and the level of disruption of the layer of water competing with the saccharide for adsorption sites on the HAP surface, suggesting that chondroitin 4-sulfate binds to the layer of solvent water rather than to HAP

Molecular dynamics simulations of bio-active phosphate-based glass surfaces

Classical molecular dynamics (MD) simulations were used to study the structural changes in the surfaces of biocompatible phosphate glasses with compositions (P2O5)0.45(CaO)x(Na2O)0.55 − x (x = 30, 35, 40) to evaluate their effect on the solubility of the material. Direct comparison of the data for the three compositions highlighted the critical role that an enhancement in Na+ concentration plays in the hydrolysis of the material, which is responsible for the release of network components into solution. The calculations also confirm that the most soluble material is (P2O5)0.45(CaO)0.30(Na2O)0.25, has the lowest calcium coordination number, thereby causing fewer cross links to phosphate chains

Structures and properties of phosphate-based bioactive glasses from computer simulation: a review

Phosphate-based bioactive glasses (PBGs) dissolve harmlessly in the body with a dissolution rate which depends sensitively on composition. This makes them proposed vectors for e.g. drug delivery, or other applications where an active component needs to be delivered at a therapeutically appropriate rate. Molecular dynamics (MD) simulations provide atomic-level structural information about PBG compositions. We review recent work to show that MD is an excellent tool to unravel the connections between the PBG glass composition, its atomic structure, and its dissolution rate, which can help to optimise PBGs for specific medical applications

Evaluación de dos fórmulas de yogur enriquecido con harina de Acheta domesticus y harina de Brosimum alicastrum Swartz, como alimentos complementarios

La prevalencia de desnutrición en niños en Guatemala es constante y se ha mantenido alta por años. Tomando en cuenta esta problemática se planteó un modelo de alimentación complementaria a base de yogur enriquecido con harinas de alto valor proteico en niños de edad preescolar en el suroccidente de Guatemala. Los tratamientos evaluados fueron yogur con harina de Acheta domesticus (grillo), yogur con harina de Brosimum alicastrum Swartz (ramón) y un grupo control. Se evaluó el peso, talla y velocidad de crecimiento durante cuatro meses brindando 125 mL de yogur cinco días por semana. La ganancia media (desviación estándar) de peso en kg fue de 3.21 (1.84), 2.22 (1.14) y 1.67 (0.64) para A. domesticus, B. alicastrum y grupo control, respectivamente. Mostrando la mezcla de yogur con harina de A. domesticus diferencia significativa frente al control (p < .05), por el contrario, no se encontró diferencia significativa (p > .05) cuando se comparó con yogur con harina de B. alicastrum. Para el incremento en talla en cm los resultados fueron 4.61 (1.13), 4.25 (1.54) y 3.07 (1.84) para A. domesticus, B. alicastrum y grupo control, respectivamente, mostrando ambas diferencias significativas frente al control (p < .05). Se determinaron los costos por dosis los cuales fueron US$0.56 (A. domesticus) y US$0.36 (B. alicastrum). Se concluye que el yogur con harina de A. domesticus fue el que presentó mejor respuesta en las variables de estudio

Las metástasis óseas del cáncer

Las metástasis óseas representan un problema clínico devastador en las neoplasias más frecuentes, especialmente en el mieloma múltiple, mama, próstata, y pulmón. Las consecuencias incluyen dolores refractarios a analgésicos convencionales, osteolisis que conlleva en ocasiones compresión medular, fracturas patológicas, y trastornos metabólicos. Recientes avances en el diagnóstico mediante técnicas de imagen, así como diversas técnicas bioquímicas, han favorecido un certero diagnóstico y seguimiento. El aumento de la supervivencia se ha mejorado mediante una aproximación multimodal en los tratamientos con la combinación de la inhibición de la osteolisis, la cirugía ortopédica profiláctica y la radioterapia. Recientes progresos en la investigación básica han determinado la huella molecular de metástasis de un tumor capaz de predecir su proclividad metastásica. La investigación básica favorecerá un conocimiento de los mecanismos básicos y llevará a elucidar dianas moleculares que favorecerán el desarrollo de fármacos capaces de prevenir, amortiguar o bloquear el proceso metastático.Bone metastases represent a devastating clinical problem in the most frequent neoplasies, especially in multiple myeloma, tumours breast, prostate and lung. The consequences include pain which is refractory to conventional analgesics, osteolysis often leading to bone-marrow compression and pathological fractures, and metabolic disorders. Recent advances in diagnosis using imaging techniques as well as different biochemical techniques have helped accurate diagnosis and follow-up. The increase in survival has improved through a multimodal approach combining, inhibition of osteolysis, with prophylactic orthopaedic surgery and radiation therapy. Recent advances in basic research have determined the molecular metastatic that can predict its proclivity to metastasize. Basic research will improve understanding of the basic mechanisms and lead to the clarification of molecular targets that will help in the development of medicines capable of preventing, decreasing or blocking the metastatic process

A content analysis in reverse logistics: a review

The purpose of this paper is to provide a comprehensive review in the various publications on the concept of Reverse Logistics (RL) and the related areas within the period 1998-2012. The content analysis approach has been opted to collect the relevant information from different books, journals, and conferences. A broad review of literature in RL from its emergence until the recent discussions have been analyzed and compared in this research. The findings show that, the theoretical construct in RL has been initiated from the conjunction features in the waste management and logistics activities. This idea had been developed by introducing the new term as RL and its definitions and contents such as the activities; key drivers; barriers to use; material flow, and networks in RL. Furthermore, the findings present the various modelling in different aspects of RL, for instance, the mathematical modelling by applying the existence methods in Multi Attribute Decision-Making Models (MADM). In addition, the environmental concerns and governmental legislatives matters and impacts, which have been highlighted, recently, on RL have been deliberated. Hence, this paper would assist the researchers and practitioners to obtain a broad review of RL in the last decade and, also provide an agenda for the future researches

New prioritized value iteration for Markov decision processes

The problem of solving large Markov decision processes accurately and quickly is challenging. Since the computational effort incurred is considerable, current research focuses on finding superior acceleration techniques. For instance, the convergence properties of current solution methods depend, to a great extent, on the order of backup operations. On one hand, algorithms such as topological sorting are able to find good orderings but their overhead is usually high. On the other hand, shortest path methods, such as Dijkstra's algorithm which is based on priority queues, have been applied successfully to the solution of deterministic shortest-path Markov decision processes. Here, we propose an improved value iteration algorithm based on Dijkstra's algorithm for solving shortest path Markov decision processes. 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Search for composite and exotic fermions at LEP 2

A search for unstable heavy fermions with the DELPHI detector at LEP is reported. Sequential and non-canonical leptons, as well as excited leptons and quarks, are considered. The data analysed correspond to an integrated luminosity of about 48 pb^{-1} at an e^+e^- centre-of-mass energy of 183 GeV and about 20 pb^{-1} equally shared between the centre-of-mass energies of 172 GeV and 161 GeV. The search for pair-produced new leptons establishes 95% confidence level mass limits in the region between 70 GeV/c^2 and 90 GeV/c^2, depending on the channel. The search for singly produced excited leptons and quarks establishes upper limits on the ratio of the coupling of the excited fermio

The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the extended Baryon Oscillation Spectroscopic Survey and from the second phase of the Apache Point Observatory Galactic Evolution Experiment

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in operation since July 2014. This paper describes the second data release from this phase, and the fourteenth from SDSS overall (making this, Data Release Fourteen or DR14). This release makes public data taken by SDSS-IV in its first two years of operation (July 2014-2016). Like all previous SDSS releases, DR14 is cumulative, including the most recent reductions and calibrations of all data taken by SDSS since the first phase began operations in 2000. New in DR14 is the first public release of data from the extended Baryon Oscillation Spectroscopic Survey (eBOSS); the first data from the second phase of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2), including stellar parameter estimates from an innovative data driven machine learning algorithm known as "The Cannon"; and almost twice as many data cubes from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous release (N = 2812 in total). This paper describes the location and format of the publicly available data from SDSS-IV surveys. We provide references to the important technical papers describing how these data have been taken (both targeting and observation details) and processed for scientific use. The SDSS website (www.sdss.org) has been updated for this release, and provides links to data downloads, as well as tutorials and examples of data use. SDSS-IV is planning to continue to collect astronomical data until 2020, and will be followed by SDSS-V.Comment: SDSS-IV collaboration alphabetical author data release paper. DR14 happened on 31st July 2017. 19 pages, 5 figures. Accepted by ApJS on 28th Nov 2017 (this is the "post-print" and "post-proofs" version; minor corrections only from v1, and most of errors found in proofs corrected