Large-scale Statistical Inference in Internet of Things Scenarios

The problem we address is performing statistical inference in Internet of Things scenarios, which are typically composed by a massive number of sensor nodes. We consider a traditional distributed scenario in which sensors make local observations about monitored phenomena and supply a central node (fusion centre) with relevant statistics for making a global decision about the state of the network. The primary contribution of the proposed statistical inference framework is that it is tailored for large-scale multisensor networks by combining non-parametric local detection approach with multiple hypotheses testing procedure that controls error rates. In particular, a local detector is employed by each sensor node. The decision problem at the detector is formulated as a binary hypothesis. The detector employs bootstrapping and non-parametric two-sample Anderson-Darling test to approximate the probability function of and calculate relevant test statistics. The fusion centre employs the False Discovery Rate control procedure for simultaneously evaluating the massive number of sensors test statistics as well as for controlling error rates. For a large number of sensors, demanding local conditions (probability models that resemble each other under the null and alternative hypotheses) and several sensors observing departure from nominal conditions, the power of the proposed statistical framework is large (above 90 %). When only few events occur, it might be challenging for the fusion centre to detect them all. To understand and address this problem we analysed the simulation results, which brought insights into the performance of the proposed statistical inference approach as well as potential ways of improving it

A Statistical Approach to Characterize and Detect Degradation Within the Barabasi-Albert Network

Social Network Analysis (SNA) is widely used by the intelligence community when analyzing the relationships between individuals within groups of interest. Hence, any tools that can be quantitatively shown to help improve the analyses are advantageous for the intelligence community. To date, there have been no methods developed to characterize a real world network as a Barabasi-Albert network which is a type of network with properties contained in many real-world networks. In this research, two newly developed statistical tests using the degree distribution and the L-moments of the degree distribution are proposed with application to classifying networks and detecting degradation within a network. The feasibility of these tests is shown by using the degree distribution for network and sub-network characterization of a selected scale-free real world networks. Further, sensitivity to the level of network degradation, via edge or node deletion, is examined with recommendation made as to the detectable size of degradation achievable by the statistical tests. Finally, the degree distribution of simulated Barabasi-Albert networks is investigated and results demonstrate that the theoretical distribution derived previously in the literature is not applicable to all network sizes. These results provide a foundation on which a statistically driven approach for network characterization can be built for network classification and monitoring

Genetic diversity, biogeography and the morpho-genetic relationship in extant planktonic foraminifera

Planktonic foraminifera are widely used as proxies for the reconstruction of past ocean conditions, a method that requires exact species classification and knowledge of their ecological adaptations. Species classification traditionally was conducted using morphological characteristics of the calcite shell. The application of genetic approaches on living planktonic foraminifera, however, challenged the classical species concept, by discovering a large number of cryptic species within the morphospecies. The present dissertation aims at establishing a connection between the fossil record and the genetic background of extant species by finding out to what degree morphologically defined species reflect real biological diversity. Molecular genetic techniques in combination with morphometric analyses were used to examine the extent of cryptic diversity in selected morphospecies and its relation to morphological traits. Furthermore, the biogeographic distribution patterns of extant species were analyzed in order to differentiate between species with local adaptations and endemism versus species with global dispersal and gene flow

Untangling hotel industry’s inefficiency: An SFA approach applied to a renowned Portuguese hotel chain

The present paper explores the technical efficiency of four hotels from Teixeira Duarte Group - a renowned Portuguese hotel chain. An efficiency ranking is established from these four hotel units located in Portugal using Stochastic Frontier Analysis. This methodology allows to discriminate between measurement error and systematic inefficiencies in the estimation process enabling to investigate the main inefficiency causes. Several suggestions concerning efficiency improvement are undertaken for each hotel studied.info:eu-repo/semantics/publishedVersio

Genetic diversity, biogeography and the morpho-genetic relationship in extant planktonic forminifera

Planktonic foraminifera are widely used as proxies for the reconstruction of past ocean conditions, a method that requires exact species classification and knowledge of their ecological adaptations. Species classification traditionally was conducted using morphological characteristics of the calcite shell. The application of genetic approaches on living planktonic foraminifera, however, challenged the classical species concept, by discovering a large number of cryptic species within the morphospecies. The present dissertation aims at establishing a connection between the fossil record and the genetic background of extant species by finding out to what degree morphologically defined species reflect real biological diversity. Molecular genetic techniques in combination with morphometric analyses were used to examine the extent of cryptic diversity in selected morphospecies and its relation to morphological traits. Furthermore, the biogeographic distribution patterns of extant species were analyzed in order to differentiate between species with local adaptations and endemism versus species with global dispersal and gene flow

Estudio tafonómico y espacial del yacimiento DS del Lecho I de la garganta de Olduvai (Tanzania)

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Geografía e Historia, leída el 16-12-2020Faunal remains recovered at early archaeological sites dated to around 2 million years (Ma) play a critical role in discussions about the evolution of early hominin behavior. Anthropogenic assemblages from this time period are scarce, however and, until recently, most of the available evidence on the behavior of early Homo has been almost exclusively obtained at the FLK Zinj site from Bed I in Olduvai Gorge (Tanzania). The recent discovery of DS (David’s Site, 1.84 Ma) and two additional hominin-made accumulations on the same paleosurface as the iconic site of FLK Zinj provides an invaluable opportunity to address key issues regarding early hominin lifestyles, particularly their subsistence behaviors and their foraging capabilities. The DS site has been extensively excavated and is exceptionally well preserved. Over the past years, significant advances in taphonomic and spatial statistical techniques have been made, which mainly involve the combination of several variables in multivariate approaches and the use of machine learning algorithms. The application of these methods to the faunal fossil record within extended frames of reference helps overcome equifinality when trying to detect the main agent of site formation and interpret site function...Los restos faunísticos recuperados en algunos de los yacimientos arqueológicos más antiguos, que datan de alrededor de dos millones de años (Ma), desempeñan un papel muy importante en las discusiones sobre la evolución del comportamiento de los homininos. Sin embargo, los conjuntos arqueológicos de origen antrópico de ese periodo son escasos y, hasta hace poco, la mayor parte de los datos disponibles sobre el comportamiento de los primeros miembros del género Homo han sido obtenidos casi exclusivamente del yacimiento FLK Zinj del Lecho I de la Garganta de Olduvai (Tanzania). El reciente descubrimiento de DS (David’s Site, 1.84 Ma) y de otras dos acumulaciones generadas por homininos sobre la misma paleosuperficie que el emblemático yacimiento de FLK Zinj, brinda una valiosa oportunidad para abordar cuestiones clave relacionadas con la forma de vida de los primeros Homo con nuevos datos, en particular sus comportamientos de subsistencia y sus capacidades depredadoras. El yacimiento se ha excavado en extensión y se encuentra excepcionalmente bien preservado. A lo largo de los últimos años, se han realizado avances significativos en las herramientas tafonómicas y espaciales estadísticas disponibles, que ahora comprenden principalmente la combinación de varias variables en aproximaciones multivariantes y el uso de algoritmos de máquinas de aprendizaje automático. La aplicación de estos métodos al registro faunístico fósil y la utilización de marcos referenciales ampliados permite superar problemas de equifinalidad a la hora de detectar el agente principal de formación del yacimiento e interpretar la funcionalidad de la localidad...Fac. de Geografía e HistoriaTRUEunpu

The Influence of the Environment on Shell Morphology and Calcification in Planktonic Foraminifera

Ein genaueres Verständnis darüber, auf welche Weise Umweltstress die Morphologie einer Population beeinflusst, könnte sich als wertvolles Werkzeug für die Rekonstruktion vergangener Stress-Intensitäten und Umweltbedingungen herausstellen. Insbesondere könnte es hilfreich sein, den Zustand einer Population (inkl. der Vorhersage von Aussterbeereignissen) zu bestimmen. Morphometrische Studien eignen sich hier besser als Populations-Dynamik Ansätze, da letztere von den natürlicherweise großen Schwankungen der Populationsgröße beeinflusst werden. Kalzitisches marines Mikroplankton (z.B. planktonische Foraminiferen) sind ein ideales Modellsystem für solche Studien, da sie in hohen Häufigkeiten im fossilen Befund erhalten bleiben und ihre gekammerte Schale eine Rekonstruktion der gesamten Ontogenie zulässt. Ihr hervorragendes Fossilisationspotential erlaubt außerdem natürliche Experimente auf ökologisch wirksamen Zeitskalen zu untersuchen, die nicht im Labor simuliert werden könnten. Planktonische Foraminiferen werden bereits häufig für geochemische und Populations-Studien verwendet, um vergangene Umweltbedingungen zu rekonstruieren. Ihre Schalen-Morphologie und -Kalzifikation wurden jedoch bisher selten untersucht, obwohl sie potentiell nützlich sind um vergangene Umweltbedingungen und Foraminiferen-Phylogenie zu rekonstruieren und rezente Ökosysteme zu monitorieren. Durch ihren hohen Anteil an der weltweiten Karbonat-Produktion könnte eine umweltbedingte Änderung ihrer Schalen-Kalzifikation zudem das ozeanische Karbonatsystem stören. Diese Studie versucht daher den Einfluss von Umweltänderungen (inkl. Stress) auf die Biometrie von Foraminiferen zu untersuchen. Zu diesem Zweck wurden mehrere Foraminiferen-Arten aus zwei pleistozänen Sedimentkernen und einer Sediment-Fallenserie bezüglich des Umwelteinflusses auf deren Morphologie und Schalen-Kalzifikation untersucht. Die Kalzifikations-Intensität (Menge an vorhandenem Kalzit) ist generell positiv mit der Karbonat-Sättigung des Meerwassers korreliert. Unter konstanter Karbonat-Sättigung zeigen sich jedoch außerdem Spezies-spezifische Einflüsse von Temperatur und Produktivität auf die Kalzifikations-Intensität der Schalen, welche den Einfluss der Karbonat-Sättigung auf diesen Parameter vermutlich zu jeder Zeit modifizieren. Kryptische Speziation stellt zudem ein signifikantes Problem für Kalzifikationsstudien dar, da die Schalen-Kalzifikation auch zw. kryptischen Spezies die traditionell oft zusammengefasst wurden deutlich unterschiedlich ist. Die Schalen-Größe war in keinem Fall mit der Spezies-Häufigkeit korreliert, was man erwartet hätte, wenn Letztere ein Maß für optimale Umweltbedingungen wäre. Zudem zeigt auch die Schalen-Kalzifikation unterschiedliche Korrelationen mit der Spezies-Häufigkeit, so dass entweder die Spezies-Häufigkeit kein brauchbarer Indikator für optimale Umweltbedingungen ist, oder dass optimale Bedingungen die Schalen-Biometrie von Foraminiferen nicht einheitlich beeinflussen. Andere morphologische Parameter zeigten charakteristische Änderungen welche auf Umwelt-Stress zurückzuführen sind. Diese Trends resultierten sämtlich in deutlichen Änderungen der Populations-Morphologie, ausgelöst durch selektive Prozesse, im Rahmen ökologisch relevanter Zeit-Skalen. Nahezu lethale Stress-Intensitäten resultierten hierbei in einer Populations-Morphologie, die deutlich von der einer weniger gestressten Population abwich. Diese Studie konnte zeigen, dass Foraminiferen-Biometrie (trotz ihrer uni-zellulären Organisationsstufe) komplex auf Umweltänderungen reagiert. Die beobachteten Reaktionen werden vom Zusammenspiel der abiotischen Umwelt, biotischer Stress-Reaktionen und kryptischer Diversität beeinflusst, so dass weitere Studien notwendig sind um diese Probleme zu minimieren.Understanding the effect of environmental stress on the morphology of a population can be developed into a versatile tool to reconstruct stress levels. Such knowledge could help to reconstruct past environments and to predict the state of a population, including future extinction. Especially for the latter aspect, morphometrics could be a valuable alternative for population-dynamics approaches, which suffer from the naturally high variability of population sizes. Calcitic marine microplankton, such as planktonic Foraminifera, offers an excellent model system for such studies. Planktonic Foraminifera occur in high abundances in the fossil record and their chambered shells allow the reconstruction of individual morphologies during their entire ontogeny. Their excellent fossilisation potential further allows to study natural experiments, which occurred over ecologically effective timescales that would have been impossible to simulate during laboratory experiments. Planktonic Foraminifera have already been broadly applied for geochemical and population studies to reconstruct past environments. Their morphology and shell calcification have in contrast been subject to comparably few studies so far. This is unfortunate, since both parameters could be useful for past environmental reconstructions, recent environmental monitoring, and phylogenetic research. Since planktonic Foraminifera have a large share on the worldwide marine calcite deposition, environmentally induced changes in their shell calcification could furthermore significantly influence the oceanic carbon pump. This study therefore aims at a better understanding of the influence of changing environments, including results of environmental stress, on the biometry of planktonic Foraminifera. For this purpose, several foraminiferal species were investigated within three selected environmental settings: two Pleistocene sediment cores and one sediment trap series. The shell calcification intensity and morphology have been investigated in light of their relation to environmental forcing and biological stress. The shell calcification intensity (amount of calcite present in the adult shell) shows signs of a universal positive correlation with carbonate saturation of the sea water. When the carbonate saturation is kept nearly constant, however, it is evident that shell calcification intensity is also influenced by other factors like temperature and productivity. Those secondary influences act species-specific and are presumably able to mediate or modify the effects of carbonate saturation. It could further be shown that cryptic speciation is a severe problem for calcification studies, because shell calcification is already significantly different between pseudo-cryptic species that have been commonly pooled together in the past. Shell size was in no case related to species abundance, what would have been expected under the assumption that species are most abundant under optimal environmental conditions. Together with the fact that shell calcification intensity is also variably correlated to species abundance, this implies that either species abundance is no versatile proxy for optimal growth conditions, or that optimal conditions are not uniformly related to biometric traits. Other phenotypic traits were observed to show characteristic deviations in relationship to environmental stress. The observed trends all led to a clear change in population morphology over ecologically relevant timescales as result of natural selective patterns. In a community which is exposed to near-lethal stress levels, this can culminate in a unique morphology that is clearly different from that of a less stressed population. The obtained results imply that foraminiferal biometry, despite their unicellular level of organisation, reacts in complex ways toward changes in the environmental setting. Those reactions are complicated by the interplay of abiotic (environment) and biotic (stress) factors and the presence of hidden diversity. Further research is needed to minimize those problems

Optimization of logical networks for the modelling of cancer signalling pathways

Cancer is one of the main causes of death throughout the world. The survival of patients diagnosed with various cancer types remains low despite the numerous progresses of the last decades. Some of the reasons for this unmet clinical need are the high heterogeneity between patients, the differentiation of cancer cells within a single tumor, the persistence of cancer stem cells, and the high number of possible clinical phenotypes arising from the combination of the genetic and epigenetic insults that confer to cells the functional characteristics enabling them to proliferate, evade the immune system and programmed cell death, and give rise to neoplasms. To identify new therapeutic options, a better understanding of the mechanisms that generate and maintain these functional characteristics is needed. As many of the alterations that characterize cancerous lesions relate to the signaling pathways that ensure the adequacy of cellular behavior in a specific micro-environment and in response to molecular cues, it is likely that increased knowledge about these signaling pathways will result in the identification of new pharmacological targets towards which new drugs can be designed. As such, the modeling of the cellular regulatory networks can play a prominent role in this understanding, as computational modeling allows the integration of large quantities of data and the simulation of large systems. Logical modeling is well adapted to the large-scale modeling of regulatory networks. Different types of logical network modeling have been used successfully to study cancer signaling pathways and investigate specific hypotheses. In this work we propose a Dynamic Bayesian Network framework to contextualize network models of signaling pathways. We implemented FALCON, a Matlab toolbox to formulate the parametrization of a prior-knowledge interaction network given a set of biological measurements under different experimental conditions. The FALCON toolbox allows a systems-level analysis of the model with the aim of identifying the most sensitive nodes and interactions of the inferred regulatory network and point to possible ways to modify its functional properties. The resulting hypotheses can be tested in the form of virtual knock-out experiments. We also propose a series of regularization schemes, materializing biological assumptions, to incorporate relevant research questions in the optimization procedure. These questions include the detection of the active signaling pathways in a specific context, the identification of the most important differences within a group of cell lines, or the time-frame of network rewiring. We used the toolbox and its extensions on a series of toy models and biological examples. We showed that our pipeline is able to identify cell type-specific parameters that are predictive of drug sensitivity, using a regularization scheme based on local parameter densities in the parameter space. We applied FALCON to the analysis of the resistance mechanism in A375 melanoma cells adapted to low doses of a TNFR agonist, and we accurately predict the re-sensitization and successful induction of apoptosis in the adapted cells via the silencing of XIAP and the down-regulation of NFkB. We further point to specific drug combinations that could be applied in the clinics. Overall, we demonstrate that our approach is able to identify the most relevant changes between sensitive and resistant cancer clones