The Ice Age: It Really Was Short

The Ice Age and its ending have been dated based on uniformitarian thinking with 14C, dendrochronology, varves and many tens of other dating methods. These dating methods have been correlated to each other, and basically have been fitted to the uniformitarian interpretation of the geological column. The methods, which are stated to be more important, have been more carefully studied. These methods are sometimes even labeled “absolute,” and are the main methods for correlation and especially dating of the last stages of the Ice Age. Fieldwork on Swedish laminated clays called (yearly) varves show climbing ripples and water escape structures, hence showing that the “varves” cannot be yearly but must instead sometimes even have been catastrophically deposited. Also, the “absolute” correlation of 14C dates and dendrochronology has been shown to be faulty, and fits a short biblical chronology very well. Glacigenic erosional and depositional landforms, for example, extent and stratigraphy of tills, moraine forms, depth of glacial erosion, and glaciofluvial sediments, all indicate one single short Ice Age

Diamictites: Ice-Ages or Gravity Flows?

A literature study directed mainly on sedimentological/erosional structures, combined with limited field work, give good grounds for rejecting the normal ice-age interpretation for relics from Pre-Pleistocene ice-ages , in favour of an interpretation as (mainly) different kinds of gravity flows. The long ages held by uniformitarian geologists for the formation of these structures are therefore no longer necessary, and the data instead point to an interpretation favouring a short timescale. Deposits from especially dense gravity flows can look very similar to till. Also, many structures formed in gravity flows can look very similar to structures formed or influenced by glaciers . Some examples are till fabric, the occurrence of erratics, polished and striated stones and bedrock, the occurence of dropstones and periglacial phenomena. The following regularly occuring structures are features of Pre-Pleistocene till ites which are never or rarely formed by glaciers, but are usually formed by gravity flows: A) the small extension and great depth of the tillites , B) the small size of erratics, C) stones pressed down in the underlying material, D-E) sorting of stones and erratics, F) channels eroded by water below the tillites , G) layers of dolomite and coal in close connection with the tillites , H) boulder pavements, I) no weathered till or soil profiles between different tillite layers , and J) the geographical occurence and extension of late Precambrian tillites . All the above speaks against the interpretation of diamictites as glacial deposits, but favours gravity flows

The origin of upper Precambrian diamictites, northern Norway: a case study applicable to diamictites in general

Upper Precambrian diamictites in Varangerfjorden (northern Norway) have been examined for evidence of origin, whether glaciogenic, gravity flow or polygenetic. Studies of geomorphology, sedimentology and surface microtextures on quartz sand grains are integrated to provide multiple pieces of evidence for the geological agents responsible for the origin of the diamictites. The documented sedimentary and erosional structures, formerly interpreted in a glaciogenic context (e.g., diamict structure, pavements and striations) have been reanalysed. Field and laboratory data demonstrate that, contrary to conclusions reached in many earlier studies, the diamictites and adjacent deposits did not originate from glaciogenic processes. Evidence from macrostructures may occasionally be equivocal or can be interpreted as representing reworked, glacially derived material. Evidence from surface microtextures, from outcrops which are believed to exhibit the most unequivocal signs for glaciation, display no imprint at all of glaciogenic processes, and a multicyclical origin of the deposits can be demonstrated. The geological context implies (and no geological data contradict this) an origin by gravity flows, possibly in a submarine fan environment. This reinterpretation of the diamictites in northern Norway may imply that the palaeoclimatological hypothesis of a deep frozen earth during parts of the Neoproterozoic has to be revised

Learning with MISELBO: The Mixture Cookbook

Mixture models in variational inference (VI) is an active field of research. Recent works have established their connection to multiple importance sampling (MIS) through the MISELBO and advanced the use of ensemble approximations for large-scale problems. However, as we show here, an independent learning of the ensemble components can lead to suboptimal diversity. Hence, we study the effect of instead using MISELBO as an objective function for learning mixtures, and we propose the first ever mixture of variational approximations for a normalizing flow-based hierarchical variational autoencoder (VAE) with VampPrior and a PixelCNN decoder network. Two major insights led to the construction of this novel composite model. First, mixture models have potential to be off-the-shelf tools for practitioners to obtain more flexible posterior approximations in VAEs. Therefore, we make them more accessible by demonstrating how to apply them to four popular architectures. Second, the mixture components cooperate in order to cover the target distribution while trying to maximize their diversity when MISELBO is the objective function. We explain this cooperative behavior by drawing a novel connection between VI and adaptive importance sampling. Finally, we demonstrate the superiority of the Mixture VAEs' learned feature representations on both image and single-cell transcriptome data, and obtain state-of-the-art results among VAE architectures in terms of negative log-likelihood on the MNIST and FashionMNIST datasets. Code available here: \url{https://github.com/Lagergren-Lab/MixtureVAEs}

Female Faculty: Why So Few and Why Care?

Despite slow ongoing progress in increasing the representation of women in academia, women remain significantly under-represented at senior levels, in particular in the natural sciences and engineering. Not infrequently, this is downplayed by bringing forth arguments such as inherent biological differences between genders, that current policies are adequate to address the issue, or by deflecting this as being “not my problem” among other examples. In this piece we present scientific evidence that counters these claims, as well as a best-practice example, Genie, from Chalmers University of Technology, where one of the authors is currently employed. We also highlight particular challenges caused by the current COVID-19 pandemic. Finally, we conclude by proposing some possible solutions to the situation and emphasize that we need to all do our part, to ensure that the next generation of academics experience a more diverse, inclusive, and equitable working environment

Förgreningar med mixturer: Fylogenetisk inferens som inte räds lite osäkerhet

Phylogeny, the study of evolutionary relationships among species and other taxa, plays a crucial role in understanding the history of life. Bayesian analysis using Markov chain Monte Carlo (MCMC) is a widely used approach for inferring phylogenetic trees, but it suffers from slow convergence in higher dimensions and is slow to converge. This thesis focuses on exploring variational inference (VI), a methodology that is believed to lead to improved speed and accuracy of phylogenetic models. However, VI models are known to concentrate the density of the learned approximation in high-likelihood areas. This thesis evaluates the current state of Variational Inference Bayesian Phylogenetics (VBPI) and proposes a solution using a mixture of components to improve the VBPI method's performance on complex datasets and multimodal latent spaces. Additionally, we cover the basics of phylogenetics to provide a comprehensive understanding of the field.Fylogeni, vilket är studien av evolutionära relationer mellan arter och andra taxonomiska grupper, spelar en viktig roll för att förstå livets historia. En ofta använd metod för att dra slutsatser om fylogenetiska träd är bayesiansk analys med Markov Chain Monte Carlo (MCMC), men den lider av långsam konvergens i högre dimensioner och kräver oändligt med tid. Denna uppsats fokuserar på att undersöka hur variationsinferens (VI) kan nyttjas inom fylogenetisk inferens med hög noggranhet. Vi fokuserar specifik på en modell kallad VBPI. Men VI-modeller är allmänt kända att att koncentrera sig på höga sannolikhetsområden i posteriorfördelningar. Vi utvärderar prestandan för Variatinal Inference Baysian Phylogenetics (VBPI) och föreslår en förbättring som använder mixturer av förslagsfördelningar för att förbättra VBPI-modellens förmåga att hantera mer komplexa datamängder och multimodala posteriorfördelningar. Utöver dettta går vi igenom grunderna i fylogenetik för att ge en omfattande förståelse av området

International legal problems concerning the use of Adaptive Camouflage

Adaptivt kamouflage är en signaturanpassningsteknik som ger stridsfordon förmågan att anpassa sin värmesignatur utefter omgivningen eller imitera andra objekts signatur, i syfte att undgå upptäckt eller identifiering.I denna studie genomförs en analys om vilka folkrättsliga problem som kan uppstå vid användandet av adaptivt kamouflage.Studiens resultat visar att de folkrättsliga problem som kan uppstå vid användningen av adaptivt kamouflage är distinktionsproblem, då tekniken möjliggör för stridsfordon att imitera signaturen av civila personbilar. Denna användning av adaptivt kamouflage kan anses som brott mot distinktionsprincipen.Adaptiv camouflage is a camouflage system which gives combat vehicles the ability to mimic the heat signature of its surroundings or copy the signature of other objects, to avoid detection or identification.This study conducts an analysis concerning the international legal problems that may arise from the use of adaptive camouflage.The result of the study show that the international legal problems that may arise from the use of adaptive camouflage are; distinction problems, when a combat vehicle can copy the heat signature of a civilian car. This use of adaptive camouflage can be seen as a violation against the principle of distinction

Tephrochronology : Methodology and correlations, Antarctic Peninsula Area

Abstract Methods for tephrochronology are evaluated, in the following way: Lake sediments <500 years old from three small Antarctic lakes were analysed for identification of tephras. Subsamples were analysed for a) grain size, and identification and concentration of volcanogenic grains, b) identification of tephra horizons, c) element abundance by EPMA WDS/EDS and LA-ICP-MS, and d) possible correlations between lakes and volcanoes. Volcanogenic minerals and shards were found all through the sediment cores in all three lakes, in different abundances. A high background population of volcanogenic mineral grains, in all samples, made the identification of tephra horizons difficult, and shards could only be distinguished by certainty after chemical analysis of elements. The tephra layers commonly could not be seen by the naked eye, and, hence they are regarded as cryptotephras. Because of the small size of recent eruptions in the research area, and the travel distance of ash, most shards are small and difficult to analyse. Nine possible tephra horizons have been recorded in the three lakes, and preliminary correlations have been made. But because of analytical problems, the proposed correlations between the lakes and possible volcanic sources are preliminary

Förgreningar med mixturer: Fylogenetisk inferens som inte räds lite osäkerhet

Phylogeny, the study of evolutionary relationships among species and other taxa, plays a crucial role in understanding the history of life. Bayesian analysis using Markov chain Monte Carlo (MCMC) is a widely used approach for inferring phylogenetic trees, but it suffers from slow convergence in higher dimensions and is slow to converge. This thesis focuses on exploring variational inference (VI), a methodology that is believed to lead to improved speed and accuracy of phylogenetic models. However, VI models are known to concentrate the density of the learned approximation in high-likelihood areas. This thesis evaluates the current state of Variational Inference Bayesian Phylogenetics (VBPI) and proposes a solution using a mixture of components to improve the VBPI method's performance on complex datasets and multimodal latent spaces. Additionally, we cover the basics of phylogenetics to provide a comprehensive understanding of the field.Fylogeni, vilket är studien av evolutionära relationer mellan arter och andra taxonomiska grupper, spelar en viktig roll för att förstå livets historia. En ofta använd metod för att dra slutsatser om fylogenetiska träd är bayesiansk analys med Markov Chain Monte Carlo (MCMC), men den lider av långsam konvergens i högre dimensioner och kräver oändligt med tid. Denna uppsats fokuserar på att undersöka hur variationsinferens (VI) kan nyttjas inom fylogenetisk inferens med hög noggranhet. Vi fokuserar specifik på en modell kallad VBPI. Men VI-modeller är allmänt kända att att koncentrera sig på höga sannolikhetsområden i posteriorfördelningar. Vi utvärderar prestandan för Variatinal Inference Baysian Phylogenetics (VBPI) och föreslår en förbättring som använder mixturer av förslagsfördelningar för att förbättra VBPI-modellens förmåga att hantera mer komplexa datamängder och multimodala posteriorfördelningar. Utöver dettta går vi igenom grunderna i fylogenetik för att ge en omfattande förståelse av området