Facial re-enactment, speech synthesis and the rise of the Deepfake

Emergent technologies in the fields of audio speech synthesis and video facial manipulation have the potential to drastically impact our societal patterns of multimedia consumption. At a time when social media and internet culture is plagued by misinformation, propaganda and “fake news”, their latent misuse represents a possible looming threat to fragile systems of information sharing and social democratic discourse. It has thus become increasingly recognised in both academic and mainstream journalism that the ramifications of these tools must be examined to determine what they are and how their widespread availability can be managed. This research project seeks to examine four emerging software programs – Face2Face, FakeApp , Adobe VoCo and Lyrebird – that are designed to facilitate the synthesis of speech and manipulate facial features in videos. I will explore their positive industry applications and the potentially negative consequences of their release into the public domain. Consideration will be directed to how such consequences and risks can be ameliorated through detection, regulation and education. A final analysis of these three competing threads will then attempt to address whether the practical and commercial applications of these technologies are outweighed by the inherent unethical or illegal uses they engender, and if so; what we can do in response

Secular change in TTG compositions: Implications for the evolution of Archaean geodynamics

It is estimated that around three quarters of Earth's first generation continental crust had been produced by the end of the Archaean Eon, 2.5 billion years ago. This ancient continental crust is mostly composed of variably deformed and metamorphosed magmatic rocks of the tonalite–trondhjemite–granodiorite (TTG) suite that formed by partial melting of hydrated mafic rocks. However, the geodynamic regime under which TTG magmas formed is a matter of ongoing debate. Using a filtered global geochemical dataset of 563 samples with ages ranging from the Eoarchaean to Neoarchaean (4.0–2.5 Ga), we interrogate the bulk rock major oxide and trace element composition of TTGs to assess evidence for secular change. Despite a high degree of scatter in the data, the concentrations or ratios of several key major oxides and trace elements show statistically significant trends that indicate maxima, minima and/or transitions in the interval 3.3–3.0 Ga. Importantly, a change point analysis of K2O/Na2O, Sr/Y and LaN/YbN demonstrates a statistically significant (>99% confidence) change during this 300 Ma period. These shifts may be linked to a fundamental change in geodynamic regime around the peak in upper mantle temperatures from one dominated by non-uniformitarian, deformable stagnant lid processes to another dominated by the emergence of global mobile lid or plate tectonic processes by the end of the Archaean. A notable change is also evident at 2.8–2.7 Ga that coincides with a major jump in the rate of survival of metamorphic rocks with contrasting thermal gradients, which may relate to the emergence of more potassic continental arc magmas and an increased preservation potential during collisional orogenesis. In many cases, the chemical composition of TTGs shows an increasing spread through the Archaean, reflecting the irreversible differentiation of the lithosphere

Ambulance Universal Chassis and Suspension Design

This MQP focuses on understanding the mechanics of the chassis of an ambulance in order to design a new chassis that can sustain the weight of a typical ambulance and also be able to suppress the surface road vibrations. We investigate all alternative suspension designs to implement and analyze the most accommodating design. Furthermore, we chose hydropneumatic suspension as the best alternative to current suspension systems in ambulances. We designed a bolt-on kit for aftermarket installation of hydropneumatic suspension into current ambulances using our 2004 Ford F-350 ambulance as a template. Our proposed chassis provides better ambulance ride quality compared to existing ambulance vehicles

Homogenising the upper continental crust : the Si isotope evolution of the crust recorded by ancient glacial diamictites

This work was supported by PhD funding to MM by the University of St Andrews School of Earth and Environmental Sciences and the Handsel scheme, as well as by NERC grant NE/R002134/1 to PS and NSF grant EAR-1321954 to RR and RG.Twenty-four composite samples of the fine-grained matrix of glacial diamictites deposited from the Mesoarchaean to Palaeozoic have been analysed for their silicon isotope composition and used to establish, for the first time, the long-term secular Si isotope record of the compositional evolution of upper continental crust (UCC). Diamictites with Archaean and Palaeoproterozoic Nd model ages show greater silicon isotope heterogeneity than those with younger model ages (irrespective of depositional age). We attribute the anomalously light Si isotope compositions of some diamictites with Archaean model ages to the presence of glacially milled banded iron formation (BIF), substantiated by the high iron content and Ge/Si in these samples. We infer that relatively heavy Si isotope signatures in some Palaeoproterozoic diamictites (all of which have Archaean Nd model ages) are due to contribution from tonalite-trondhjemite-granodiorites (TTGs), evidenced by the abundance of TTG clasts. By the Neoproterozoic (with model ages ranging from 2.3 to 1.8 Ga), diamictite Si isotope compositions exhibit a range comparable to modern UCC. This reduced variability through time is interpreted as reflecting the decreasing importance of BIF and TTG in post-Archaean continental crust. The secular evolution of Si isotopes in the diamictites offers an independent test of models for the emergence of stable cratons and the onset of horizontal mobile-lid tectonism. The early Archaean UCC was heterogeneous and incorporated significant amounts of isotopically light BIF, but following the late Archaean stabilisation of cratons, coupled with the oxygenation of the atmosphere that led to the reduced neoformation of BIF and diminishing quantities of TTGs, the UCC became increasingly homogeneous. This homogenisation likely occurred via reworking of preexisting crust, as evidenced by Archaean Nd model ages recorded in younger diamictites.Publisher PDFPeer reviewe

Apatite: a U-Pb thermochronometer or geochronometer?

Apatite is an accessory mineral that is frequently found in both igneous and clastic sedimentary rocks. It is conventionally considered to be characterized by a closure temperature range between 375 and 600 °C and hence has been employed to address mid-temperature thermochronology questions relevant to the reconstruction of thermal events in the middle to lower crust. However, questions remain as to whether apatite faithfully records thermally-activated volume diffusion profiles, or rather is influenced by recrystallization and new growth processes. We present a case study of two apatite samples from the Akia Terrane in Greenland that help chart some of the post magmatic history of this region. Apatite in a tonalitic gneiss has distinct U-enriched rims and its U-Pb apparent ages correlate with Mn chemistry, with a high Mn group yielding an age of c. 2813 Ma. The U-Pb and trace element chemistry and morphology support an interpretation in which these apatite crystals are originally igneous and record cooling after metamorphism, with subsequent generation of discrete new rims. Epidote observed in the sample implies a <600 °C fluid infiltration event associated with apatite rims. The second sample, from a granitic leucosome, contains apparently homogeneous apatite, however U-Pb analyses define two distinct discordia arrays with different common Pb components. An older, c. 2490 Ma, component is associated with elevated Sr, whereas a younger, c. 1800 Ma, component has lower Sr concentration. A depth profile reveals an older core with progressively younger ages towards a compositionally discrete late Paleoproterozoic rim. The chemical and age profiles do not directly correspond, implying different diffusion rates between trace elements and U and Pb. The variation in core ages is interpreted to reflect radiogenic-Pb loss from a metamorphic population during new rim growth. The younger, c. 1800 Ma U-Pb age is interpreted to date new apatite growth from a compositionally distinct reservoir driven by tectonothermal and fluid activity, consistent with regional mica Ar-Ar ages. Results from these two samples show that recrystallization, dissolution and regrowth processes likely formed the younger rim overgrowths, and at temperatures below those often considered to be closure temperatures for Pb diffusion in apatite. The results from these samples imply many apatite grains may not record simple thermally activated Pb diffusion profiles and cautions against inversion of apatite U-Pb data to thermal histories without detailed knowledge of the grain growth/alteration processes

Identification of a Pre-Contact Polar Bear Victim at Native Point, Southampton Island, Nunavut, Using 3D Technology and a Virtual Zooarchaeology Collection

The skeletal remains of an adult Sadlermiut woman with obvious trauma to her cranial and post-cranial skeleton were excavated from Native Point (KkHh-1), Southampton Island, Nunavut, in 1954. In order to determine the possible cause of this damage, we first documented the skeletal injuries using traditional bioarchaeological techniques. We then created a three-dimensional model of the cranium and mandible to permit better visualization and analysis of the cranial lesions, some of which were obscured by post-depositional weathering. This model was imported into a virtual environment in order to compare the lesions with the craniodental structure of four Arctic carnivore species available as digital models through the Virtual Zooarchaeology of the Arctic Project (VZAP), an online comparative faunal collection. We eliminated all but the polar bear (Ursus maritimus) using this process, which suggested that an individual of this species was responsible for the skeletal trauma. We further identified a minimum number of “bites” on the cranium, some with overlapping lesions, which suggested a possible attack sequence. Use of a virtual environment and an online comparative collection were critical to this process and represent a new technique for evaluating past skeletal trauma and its causes.En 1954, lors de travaux archéologiques sur le site Native Point (KkHh-1), île Southampton, Nunavut, les restes du squelette d’une femme adulte de la culture Sadlermiut portant des signes évidents de traumatismes crânien et post-crânien avaient été excavés. Dans le but de déterminer les causes possibles de ces dommages, nous avons d’abord documenté les lésions squelettiques à l’aide de techniques bio-archéologiques traditionnelles. Ensuite, nous avons créé un modèle en trois dimensions du crâne et de la mandibule pour permettre de bien visualiser et analyser les lésions crâniennes, notamment parce que certaines d’entre elles étaient obscurcies par l’érosion post-dépositionnelle. Ce modèle a été importé dans un environnement virtuel afin de comparer les lésions à la structure cranio-dentaire de quatre espèces carnivores provenant de l’Arctique dont les modèles figurent déjà dans la collection ostéologique comparative en ligne du projet VZAP (Virtual Zooarchaeology of the Arctic Project). Nous avons ainsi éliminé tous les carnivores à l’exception de l’ours polaire (Ursus maritimus), laissant penser qu’un membre de cette espèce serait responsable des traumatismes du squelette de cette femme. Nous avons également identifié des morsures sur le crâne de cette femme, suggérant une possible séquence d’attaques, ne serait-ce que par la présence d’une série de lésions qui se chevauchent. L’utilisation d’un environnement virtuel et d’une collection comparative virtuelle a joué un rôle déterminant dans ce processus et représente une nouvelle technique pour évaluer les traumatismes squelettiques anciens et leurs causes

Silicon isotopes in an Archaean migmatite confirm seawater silicification of TTG sources

Funding: This work was made possible by PhD funding to MM by the University of St Andrews School of Earth and Environmental Sciences and the Handsel scheme, in addition to NERC grant NE/R002134/1 to PS.Unraveling ancient melting processes is key to understanding how the earliest, tonalite-trondhjemite-granodiorite (TTG)-dominated continental crust formed from partial melting of amphibolite. Application of silicon isotope analysis to ancient crust reveals that Archaean TTGs exhibit consistently high Si isotope values (δ30Si) compared to modern granitoids, attributed to seawater-derived silica introduced by either (a) partial melting of variably silicified basalts or (b) assimilation of authigenic silica-rich marine lithologies in the melt source. However, both mechanisms can introduce highly variable δ30Si, conflicting with the strikingly consistent δ30Si compositions of Archaean TTGs. This study investigates an alternative model, whereby the distinct mineralogy and chemistry of TTG melt sources impart a distinct silicon isotope composition to the melt, compared with “modern” granitoids. We measured δ30Si in component parts (melanosome and leucosome) of an Archaean (2.7 Ga) mafic migmatite and coeval amphibolites and mafic granulites from the Kapuskasing uplift, Canada, to explore how Si isotopes fractionate during incipient TTG melt formation. Our data reveal leucosome (i.e., melt) exhibits consistently high δ30Si values compared to a relatively isotopically lighter melanosome (i.e., residuum). We also derive inter-mineral silicon isotope fractionation factors for mineral separates that agree well with those of ab initio estimates for the same minerals and show that the magnitude of equilibrium fractionation between TTG source rock and melt replicates that in Phanerozoic granitoids. We conclude the effects of magmatic differentiation on δ30Si have remained consistent throughout Earth history, meaning that Archaean TTGs must require a source isotopically heavier than unaltered basalt, as reflected by our amphibolites and mafic migmatite components. The consistently heavy δ30Si of seawater through Earth history, and the high SiO2 content of amphibolites relative to coeval leucosome-free granulites in our study area, imply seawater silicification is the source of the observed high δ30Si. Thus, the consistently heavy Si isotope compositions measured in Archaean melt products define a unique aspect of ancient crust formation: that of the silicification of TTG source rock, implying the intrinsic involvement of a primeval hydrosphere.Publisher PDFPeer reviewe

Crustal rejuvenation stabilised Earth’s first cratons

This work was funded by Australian Research Council grant FL160100168 and Australian Research Council grant DP180100580.The formation of stable, evolved (silica-rich) crust was essential in constructing Earth’s first cratons, the ancient nuclei of continents. Eoarchaean (4000–3600 million years ago, Ma) evolved crust occurs on most continents, yet evidence for older, Hadean evolved crust is mostly limited to rare Hadean zircons recycled into younger rocks. Resolving why the preserved volume of evolved crust increased in the Eoarchaean is key to understanding how the first cratons stabilised. Here we report new zircon uranium-lead and hafnium isotope data from the Yilgarn Craton, Australia, which provides an extensive record of Hadean–Eoarchaean evolved magmatism. These data reveal that the first stable, evolved rocks in the Yilgarn Craton formed during an influx of juvenile (recently extracted from the mantle) magmatic source material into the craton. The concurrent shift to juvenile sources and onset of crustal preservation links craton stabilisation to the accumulation of enduring rafts of buoyant, melt-depleted mantle.Publisher PDFPeer reviewe

Threat Models over Space and Time: A Case Study of E2EE Messaging Applications

Threat modelling is foundational to secure systems engineering and should be done in consideration of the context within which systems operate. On the other hand, the continuous evolution of both the technical sophistication of threats and the system attack surface is an inescapable reality. In this work, we explore the extent to which real-world systems engineering reflects the changing threat context. To this end we examine the desktop clients of six widely used end-to-end-encrypted mobile messaging applications to understand the extent to which they adjusted their threat model over space (when enabling clients on new platforms, such as desktop clients) and time (as new threats emerged). We experimented with short-lived adversarial access against these desktop clients and analyzed the results with respect to two popular threat elicitation frameworks, STRIDE and LINDDUN. The results demonstrate that system designers need to both recognise the threats in the evolving context within which systems operate and, more importantly, to mitigate them by rescoping trust boundaries in a manner that those within the administrative boundary cannot violate security and privacy properties. Such a nuanced understanding of trust boundary scopes and their relationship with administrative boundaries allows for better administration of shared components, including securing them with safe defaults