614 research outputs found

    Speech recognition by recursive stochastic modelling

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    Complicit in the Murder Program: Podcasting Dystopia in The Intercept’s Evening at the Talk House (2018)

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    Podcasting is an increasingly popular audio-only, on-demand narrative form that draws millions of listeners, both within the U.S. and worldwide. While podcast scholars are excited about podcasts’ potential to create content that finds no place in the mainstream media, they have not yet investigated how contemporary fictional podcasts can create societal critiques. This paper investigates the political potential of critical news platform The Intercept’s special feature audio play Evening at the Talk House (2018) by analyzing its content, form, and funding model. I will argue that Evening at the Talk House effectively uses the affordances of both the podcast and the dystopian narrative mode to expose the U.S. empire for American citizens by collapsing the distinction between the ‘good’ and safe homeland and the evil ‘other’ abroad. Evening at the Talk House, thus, raises questions about the complicity of regular citizens in enabling ‘murder programs’ (e.g. drone strikes, wars in Iraq and Afghanistan) as citizens actively take part in and become the victims of imperial violence. However, consistent with The Intercept’s daily reporting, Talk House fails to address a major motivation of the U.S. empire: establishing and maintaining global capitalism. This neglect can be explained by considering how the platform was established, as tech billionaire Pierre Omidyar provided its funding

    Impaired ATP synthase assembly associated with a mutation in the human ATP synthase subunit 6 gene

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    Mutations in human mitochondrial DNA are a well recognized cause of disease. A mutation at nucleotide position 8993 of human mitochondrial DNA, located within the gene for ATP synthase subunit 6, is associated with the neurological muscle weakness, ataxia, and retinitis pigmentosa (NARP) syndrome. To enable analysis of this mutation in control nuclear backgrounds, two different cell lines were transformed with mitochondria carrying NARP mutant mitochondrial DNA. Transformant cell lines had decreased ATP synthesis capacity, and many also had abnormally high levels of two ATP synthase sub-complexes, one of which was F1-ATPase. A combination of metabolic labeling and immunoblotting experiments indicated that assembly of ATP synthase was slowed and that the assembled holoenzyme was unstable in cells carrying NARP mutant mitochondrial DNA compared with control cells. These findings indicate that altered assembly and stability of ATP synthase are underlying molecular defects associated with the NARP mutation in subunit 6 of ATP synthase, yet intrinsic enzyme activity is also compromised

    Epidemiological investigations into the 2007 outbreak of equine influenza in Australia

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    Equine influenza is a highly contagious and widespread viral respiratory disease of horses and other equid species, characterised by fever and a harsh dry cough. Prior to August 2007, Australia was one of only three countries to have remained free of equine influenza. An incursion of equine influenza virus H3N8 in that month resulted in a four-month outbreak during which approximately 69,000 horses were infected on an estimated 9599 premises across two States. Most of the geographic spread occurred within the first 10 days and was associated with the movement of infected horses prior to the implementation of movement controls. The outbreak was contained through a series of interventions that ultimately led to the eradication of equine influenza from Australia. During and immediately after the outbreak, intensive epidemiological investigations, laboratory and retrospective analytical studies were conducted culminating in a series of detailed reports and publications, and the collation of a highly detailed outbreak dataset. Further research into the factors that contributed to the spread of the outbreak and the effectiveness of measures implemented to control and contain it was considered important. The aim of this thesis was therefore to investigate the factors that contributed to the spread of the 2007 equine influenza outbreak in Australia and to develop statistical methods and tools useful for informing the surveillance and control of future emergency animal disease events. A case-control study was conducted to investigate premises-level risk factors, specifically whether compliance with advised biosecurity measures prevented the spread of equine influenza onto horse premises. Horse owners and managers on 200 properties across highly affected areas of New South Wales were interviewed. The proximity of premises to the nearest infected premises was the factor most strongly associated with case status. Case premises were more likely than control premises to be within 5 km and beyond 10km of an infected premises. Having a footbath in place on the premises before any horses were infected was associated with a nearly four-fold reduction in odds of infection (odds ratio = 0.27; 95% confidence interval: iv 0.09, 0.83). This protective association may have reflected overall premises biosecurity standards related to the fomite transmission of equine influenza: there was high correlation amongst several, generally protective, variables representing personal ‗barrier hygiene‘ biosecurity measures (hand-washing, changing clothes and shoes, and having a footbath in place). The movement of infected horses and local disease diffusion were known to be important mechanisms of spread early in this outbreak. A network analysis was conducted to investigate the relative contribution of each mechanism. The relationship between infected and susceptible horse premises (contact through animal movements and spatial proximity) was described by constructing a mixed transmission network. During the first 10 days of the 2007 equine influenza outbreak in Australia, horses on 197 premises were infected. A new likelihood-based approach was developed and it was estimated that 28.3% of early disease spread (prior to the implementation of horse movement restrictions) was through the movement of infected horses (95% CI: 25.6, 31.0%). Most local spread was estimated to have occurred within 5 km of infected premises. Based on a direct estimate of the shape of the spatial transmission kernel, the incidence beyond 15 km was very low. The median distance that infected horses were moved was 123 km (range 4–579 km). In an extension of the network analysis, novel methods were developed to delineate spatial clusters of infected premises and describe the sequence of cluster formation and the widespread dispersal experienced during the first 30 days of the outbreak. Premises identified as infected by the movement of infected horses were found to be critical to the seeding of infection in spatial clusters. Combined analysis of spatial and contact network data demonstrated that early in this outbreak local spread emanated outwards from the small number of infected premises in the contact network, up to a distance of around 15 km. A purely spatial method of modelling epidemic spread (kriging) was imprecise in describing the pattern of spread during this early phase of the outbreak (explaining only 13% of the variation in estimated date of onset of v infected premises), because early dissemination was dominated by network-based spread. Prior to this thesis, there was an abundance of anecdotal information regarding the role of meteorological factors and other environmental determinants in the spread of the 2007 equine influenza outbreak in Australia. A survival analysis was therefore conducted to empirically estimate the association between meteorological variables (wind, air temperature, relative humidity and rainfall) and time-to-infection in the largest cluster of the outbreak, in northwest Sydney. The equine influenza outbreak dataset was structured to enable generalised Cox regression modelling of the association between time-varying covariates representing premiseslevel meteorological conditions. The cumulative incidence in the northwest Sydney cluster was estimated to be 53.0% (95% CI: 51.4, 54.7%). Local spatial spread of equine influenza was found to be associated with relative humidity, air temperature and wind velocity. Meteorological conditions 3–5 days prior were strongly associated with hazard of influenza infection. Strong winds (>30 km hour-1) from the direction of nearby infected premises were associated with influenza infection, as was low relative humidity (<60%). A nonlinear relationship was observed with air temperature: the lowest hazard was on days when maximum daily air temperature was between 20–25 °C. Drawing on the findings of the above studies, a spatially-explicit stochastic epidemic model of equine influenza transmission was developed to investigate the underlying disease process, estimate the effectiveness of several control measures applied during the 2007 outbreak and to provide a dynamic modelling framework for rapid assessment of future equine influenza outbreaks in Australia. A reversible jump Markov chain Monte Carlo algorithm was used to estimate Bayesian posterior distributions of key epidemiological parameters based on data from two highly affected regions. A large amount of regional heterogeneity was observed in the underlying epidemic process, the estimated rate of decay of transmission by distance from infected premises, the intra-premises transmission rate and the effect of premises area. Model outputs were highly cross-correlated both temporally and spatially with data observed during vi the 2007 outbreak, and with outputs of a previous model. Pseudo-validation of the model against data, not used in its development, demonstrated of how it may be applied to develop rapid assessments of future outbreaks affecting horse populations in comparable regions to those studied. The study results documented in this thesis have elucidated the key factors underlying the spread of the 2007 equine influenza outbreak in Australia, and presented new methods of describing such rapidly spreading epidemics. The movement of infected horses, meteorological variables (air temperature, humidity and wind speed), on-farm biosecurity measures and intrinsic features of horse premises (proximity to other infected premises, numbers of horses held and premises area) were all important variables that influenced the spread of infection onto horse premises. These insights allow development of better policy and control programs in the event of a future equine influenza virus incursion

    Mitochondrial membrane biogenesis: phospholipids and proteins go hand in hand

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    Mitochondrial membrane biogenesis requires the import and synthesis of proteins as well as phospholipids. How the mitochondrion regulates phospholipid levels and maintains a tight protein-to-phospholipid ratio is not well understood. Two recent papers (Kutik, S., M. Rissler, X.L. Guan, B. Guiard, G. Shui, N. Gebert, P.N. Heacock, P. Rehling, W. Dowhan, M.R. Wenk, et al. 2008. J. Cell Biol. 183:1213–1221; Osman, C., M. Haag, C. Potting, J. Rodenfels, P.V. Dip, F.T. Wieland, B. BrĂŒgger, B. Westermann, and T. Langer. 2009. J. Cell Biol. 184:583–596) identify novel regulators of mitochondrial phospholipid biosynthesis. The biochemical approach of Kutik et al. (2008) uncovered an unexpected role of the mitochondrial translocator assembly and maintenance protein, Tam41, in the biosynthesis of cardiolipin (CL), the signature phospholipid of mitochondria. The genetic analyses of Osman et al. (2009) led to the discovery of a new class of mitochondrial proteins that coordinately regulate CL and phosphatidylethanolamine, another key mitochondrial phospholipid. These elegant studies highlight overlapping functions and interdependent roles of mitochondrial phospholipid biosynthesis and protein import and assembly

    Iterative orthology prediction uncovers new mitochondrial proteins and identifies C12orf62 as the human ortholog of COX14, a protein involved in the assembly of cytochrome c oxidase

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    BACKGROUND: Orthology is a central tenet of comparative genomics and ortholog identification is instrumental to protein function prediction. Major advances have been made to determine orthology relations among a set of homologous proteins. However, they depend on the comparison of individual sequences and do not take into account divergent orthologs. RESULTS: We have developed an iterative orthology prediction method, Ortho-Profile, that uses reciprocal best hits at the level of sequence profiles to infer orthology. It increases ortholog detection by 20% compared to sequence-to-sequence comparisons. Ortho-Profile predicts 598 human orthologs of mitochondrial proteins from Saccharomyces cerevisiae and Schizosaccharomyces pombe with 94% accuracy. Of these, 181 were not known to localize to mitochondria in mammals. Among the predictions of the Ortho-Profile method are 11 human cytochrome c oxidase (COX) assembly proteins that are implicated in mitochondrial function and disease. Their co-expression patterns, experimentally verified subcellular localization, and co-purification with human COX-associated proteins support these predictions. For the human gene C12orf62, the ortholog of S. cerevisiae COX14, we specifically confirm its role in negative regulation of the translation of cytochrome c oxidase. CONCLUSIONS: Divergent homologs can often only be detected by comparing sequence profiles and profile-based hidden Markov models. The Ortho-Profile method takes advantage of these techniques in the quest for orthologs

    Reduction of the ATPase inhibitory factor 1 (IF1) leads to visual impairment in vertebrates

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    In vertebrates, mitochondria are tightly preserved energy producing organelles, which sustain nervous system development and function. The understanding of proteins that regulate their homoeostasis in complex animals is therefore critical and doing so via means of systemic analysis pivotal to inform pathophysiological conditions associated with mitochondrial deficiency. With the goal to decipher the role of the ATPase inhibitory factor 1 (IF1) in brain development, we employed the zebrafish as elected model reporting that the Atpif1a−/− zebrafish mutant, pinotage (pnttq209), which lacks one of the two IF1 paralogous, exhibits visual impairment alongside increased apoptotic bodies and neuroinflammation in both brain and retina. This associates with increased processing of the dynamin-like GTPase optic atrophy 1 (OPA1), whose ablation is a direct cause of inherited optic atrophy. Defects in vision associated with the processing of OPA1 are specular in Atpif1−/− mice thus confirming a regulatory axis, which interlinks IF1 and OPA1 in the definition of mitochondrial fitness and specialised brain functions. This study unveils a functional relay between IF1 and OPA1 in central nervous system besides representing an example of how the zebrafish model could be harnessed to infer the activity of mitochondrial proteins during development

    Prohibitins Are Required for Cancer Cell Proliferation and Adhesion

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    Prohibitin 1 (PHB1) is a highly conserved protein that together with its homologue prohibitin 2 (PHB2) mainly localizes to the inner mitochondrial membrane. Although it was originally identified by its ability to inhibit G1/S progression in human fibroblasts, its role as tumor suppressor is debated. To determine the function of prohibitins in maintaining cell homeostasis, we generated cancer cell lines expressing prohibitin-directed shRNAs. We show that prohibitin proteins are necessary for the proliferation of cancer cells. Down-regulation of prohibitin expression drastically reduced the rate of cell division. Furthermore, mitochondrial morphology was not affected, but loss of prohibitins did lead to the degradation of the fusion protein OPA1 and, in certain cancer cell lines, to a reduced capability to exhibit anchorage-independent growth. These cancer cells also exhibited reduced adhesion to the extracellular matrix. Taken together, these observations suggest prohibitins play a crucial role in adhesion processes in the cell and thereby sustaining cancer cell propagation and survival

    NDUFS4 deletion triggers loss of NDUFA12 in Ndufs4−/− mice and Leigh syndrome patients: A stabilizing role for NDUFAF2

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    Mutations in NDUFS4, which encodes an accessory subunit of mitochondrial oxidative phosphorylation (OXPHOS) complex I (CI), induce Leigh syndrome (LS). LS is a poorly understood pediatric disorder featuring brain-specific anomalies and early death. To study the LS pathomechanism, we here compared OXPHOS proteomes between various Ndufs4−/− mouse tissues. Ndufs4−/− animals displayed significantly lower CI subunit levels in brain/diaphragm relative to other tissues (liver/heart/kidney/skeletal muscle), whereas other OXPHOS subunit levels were not reduced. Absence of NDUFS4 induced near complete absence of the NDUFA12 accessory subunit, a 50% reduction in other CI subunit levels, and an increase in specific CI assembly factors. Among the latter, NDUFAF2 was most highly increased. Regarding NDUFS4, NDUFA12 and NDUFAF2, identical results were obtained in Ndufs4−/− mouse embryonic fibroblasts (MEFs) and NDUFS4-mutated LS patient cells. Ndufs4−/− MEFs contained active CI in situ but blue-native-PAGE highlighted that NDUFAF2 attached to an inactive CI subcomplex (CI-830) and inactive assemblies of higher MW. In NDUFA12-mutated LS patient cells, NDUFA12 absence did not reduce NDUFS4 levels but triggered NDUFAF2 association to active CI. BN-PAGE revealed no such association in LS patient fibroblasts with mutations in other CI subunit-encoding genes where NDUFAF2 was attached to CI-830 (NDUFS1, NDUFV1 mutation) or not detected (NDUFS7 mutation). Supported by enzymological and CI in silico structural analysis, we conclude that absence of NDUFS4 induces near complete absence of NDUFA12 but not vice versa, and that NDUFAF2 stabilizes active CI in Ndufs4−/− mice and LS patient cells, perhaps in concert with mitochondrial inner membrane lipids
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