Distortion estimation and compensation by multi-tone sweep

Audio conferencing systems typically include an echo canceller to remove echo from the loudspeaker that is picked up by the microphone. The echo canceller includes a linear echo canceller for removing linear echos, and a residual echo suppressor for suppressing residual non-linear echos. The residual echo suppressor functions based upon a characterization of the inter-modulation products generated by the audio system, e.g., provided as a distortion map generated using a single-tone sweep at different volumes on the loudspeaker and measuring the distortion at the microphone. Extending this approach to multi-tone input signals has prohibitive memory requirements

Noise and howling mitigation in audio/video conferencing

Loudspeaker-to-microphone feedback causes echoes in audio/video conferences. A microphone typically has a background-noise level estimator, which provides noise-level estimates for the purpose of setting parameters within acoustic echo cancelers (AEC), noise reducers, comfort noise generators (CNG), etc. Output from a noisy loudspeaker may be picked up by the microphone, adding to background noise already present at the microphone. Loudspeaker noise, when picked up by the microphone, causes a misestimation of background noise, which in turn leads to incorrect parameter setting. This can lead to divergence of adaptive AEC circuitry, audible echoes, howling, etc

Tropical Materialisms: Toward Decolonial Poetics, Practices and Possibilities

Tropical Materialisms concur on at least three things: humans are always entangled with non-human/material agents; such entanglement is necessary for any creative act to take place; and these same entanglements allow us to interrogate and re-evaluate preconceived notions about the world. This Special Issue aligns itself with the fields of new materialism and posthumanism. What is particularly exciting is the opportunity to rearticulate these fields in tropical terms, that is, with scholarly and creative practices from and about the tropical world. This focus is crucial given that current scholarship in new materialism and posthumanism predominantly comes from European temperate contexts and is informed by Western philosophies. In order to decolonize the ontological turn, this Special Issue recognises not only that colonial knowledge systems impacted the tropics, but also that matter’s liveliness was and is well understood in Indigenous cosmologies, ancient philosophies and ‘animist materialism’. The papers collected together in this special issue offers materialisms informed by decolonizing intuitions. They variously demonstrate how the tropics, as geographic zone and as pertaining to poetics (via tropes ), can theoretically inform and historically problematise new materialism and posthumanism. They offer new vocabularies through which discourses on tropical materialism may be initiated; and a cartography of practices across disciplinary fields which demonstrate what this tropical materialism may be. The Special Issue collection it itself a form of poiesis: a creative engagement with the world

Exploring the competition between variable renewable electricity and a carbon-neutral baseload technology

In this paper we explore the competition between variable renewable energy sources (VRE) and a carbon-neutral baseload technology in the transition to a low-carbon power system. We study a stylized system subject to a gradually increasing carbon tax using an agent-based model where agents are power companies investing in new capacity. The agents make predictions of the profitability of different investment options. Five electricity generating technologies are available in the model: coal, gas, wind, solar PV and a more expensive carbon-neutral baseload technology. We compare the output from our model with a corresponding optimization model. We present two main findings: (1)\ua0installed capacity of VRE initially increases with a carbon tax. However, once the carbon tax has reached a certain level the installed capacity of VRE starts to decline due to competition with the stylized carbon-neutral baseload technology. (2)\ua0With limited foresight we find that the model underinvests (first 25 years) in wind and then overinvests in wind compared to the optimal solution. The reasons for these dynamic phenomena are explained and an extensive sensitivity analysis is carried out

Using iPSC-derived cortical organoids to study disease mechanisms of POLG-disease and explore new therapeutic strategies

POLG-related diseases are a set of severe mitochondrial myopathies caused by a mutation in the POLG gene. The POLG gene encodes for the catalytic subunit of the mitochondrial DNA (mtDNA) polymerase gamma (Pol-γ). Pol-γ is responsible for the replication and maintenance of mtDNA, and dysfunction of Pol-γ due to mutations in the POLG gene leads to mtDNA depletion and an accumulation of mtDNA deletions over time. This impairment of the mtDNA leads to dysfunctions in the mitochondrial respiratory chain, leading to severe cellular energy depletion as a result of reduced adenine triphosphate (ATP) production. POLG-related diseases have a large degree of variance in the age that symptoms manifest and the severity of the symptoms. POLG-related diseases manifest mainly in postmitotic tissues such as those of the brain, skeletal muscle and liver, and mutations in the POLG gene have been associated with several disorders such as Alpers-Huttenlocher syndrome (AHS), progressive external ophthalmoplegia (PEO), and childhood myocerebrohepatopathy syndrome (MCHS). POLG-related disorders often manifest severe neurological symptoms, and there are currently no effective treatments available for POLG-diseases. One of the main challenges in conducting studies of POLG-related disease is the limited availability of patient tissues available for study. To overcome this challenge, we have in this study developed a method for generating cortical organoids (COs) from patient derived induced pluripotent stem cells (iPSCs). In this study we have generated COs from iPSCs from a patient carrying the mutations p.Ala467Thr and p.Trp748Ser, known to be associated with several POLG-related neurodegenerative disorders including AHS. In this thesis we attempt to determine the ability of generated POLG COs to accurately model the phenotypic features of POLG-disease, as well as an initial investigation into nicotinamide riboside (NR) as a potential novel therapeutic treatment option. We discovered distinct differences in the growth patterns of POLG COs, notably a tendency for POLG COs to fuse together in culture at a far greater rate than the control. Flow cytometry analysis also revealed POLG COs had lowered cell viability, and overall decreased expression of markers indicating depletion of neuronal mass, loss of mitochondrial mass, complex I (C1) depletion and loss of mtDNA volume. However, when normalizing the mitochondrial mass to the neuronal mass, and normalizing mtDNA volume and C1 to the mitochondrial mass a reduction was no longer observed. NR supplementation was seen to have a rescuing effect on the POLG COs, increasing cell viability and increasing expression of markers indicating increased overall neuronal mass, mitochondrial mass, C1 and mtDNA. But the same trend was not observed in normalized values. This study is part of our preliminary investigations into the utilization of COs as a potential modeling system for POLG-related disease, as such this study was conducted on a limited number of repeats and lacks any statistical analysis. Therefore, it is important to keep in mind that these are preliminary findings, and that further investigation is required to confirm if these findings are significant. Furthermore, the methodology revealed a certain degree of limitations including difficulties with imaging, variable staining efficiency, and an overall low viable cell population throughout samples showing that there is still a need to improve and optimize our protocols. However, the findings of this study have given valuable insight into the cellular impacts of POLG mutations and serve as a foundation for further research in this field. In conclusion, this study has opened a new frontier in the study of POLG and other mitochondrial diseases and holds promise for the development of novel therapeutic strategies.Masteroppgave i biomedisinBMED395MAMD-MEDB

BMI, sex and outcomes in hospitalised patients in western Sweden during the COVID-19 pandemic

High body mass index (BMI) is associated with severe COVID-19 but findings regarding the need of intensive care (IC) and mortality are mixed. Using electronic health records, we identified all patients in western Sweden hospitalised with COVID-19 to evaluate 30-day mortality or assignment to IC. Adjusted logistic regression models were used to estimate odds ratios (OR) and 95% confidence intervals (CI) for outcomes. Of totally 9761 patients, BMI was available in 7325 (75%), included in the study. There was a marked inverse association between BMI and age (underweight and normal weight patients were on average 78 and 75\ua0years, whereas overweight and obese were 68 and 62\ua0years). While older age, male sex and several comorbidities associated with higher mortality after multivariable adjustment, BMI did not. However, BMI ≥ 30\ua0kg/m2\ua0(OR 1.46, 95% CI 1.21–1.75) was associated with need of IC; this association was restricted to women (BMI ≥ 30; OR 1.96 (95% CI 1.41–2.73), and not significant in men; OR 1.22 (95% CI 0.97–1.54). In this comprehensive hospital population with COVID-19, BMI was not associated with 30-day mortality risk. Among the obese, women, but not men, had a higher risk of assignment to IC

ProDeGe: a computational protocol for fully automated decontamination of genomes

Single amplified genomes and genomes assembled from metagenomes have enabled the exploration of uncultured microorganisms at an unprecedented scale. However, both these types of products are plagued by contamination. Since these genomes are now being generated in a high-throughput manner and sequences from them are propagating into public databases to drive novel scientific discoveries, rigorous quality controls and decontamination protocols are urgently needed. Here, we present ProDeGe (Protocol for fully automated Decontamination of Genomes), the first computational protocol for fully automated decontamination of draft genomes. ProDeGe classifies sequences into two classes—clean and contaminant—using a combination of homology and feature-based methodologies. On average, 84% of sequence from the non-target organism is removed from the data set (specificity) and 84% of the sequence from the target organism is retained (sensitivity). The procedure operates successfully at a rate of ~0.30 CPU core hours per megabase of sequence and can be applied to any type of genome sequence

Scattering theory for Klein-Gordon equations with non-positive energy

We study the scattering theory for charged Klein-Gordon equations: \{{array}{l} (\p_{t}- \i v(x))^{2}\phi(t,x) \epsilon^{2}(x, D_{x})\phi(t,x)=0,[2mm] \phi(0, x)= f_{0}, [2mm] \i^{-1} \p_{t}\phi(0, x)= f_{1}, {array}. where: \epsilon^{2}(x, D_{x})= \sum_{1\leq j, k\leq n}(\p_{x_{j}} \i b_{j}(x))A^{jk}(x)(\p_{x_{k}} \i b_{k}(x))+ m^{2}(x), describing a Klein-Gordon field minimally coupled to an external electromagnetic field described by the electric potential $v(x)$ and magnetic potential $\vec{b}(x)$. The flow of the Klein-Gordon equation preserves the energy: h[f, f]:= \int_{\rr^{n}}\bar{f}_{1}(x) f_{1}(x)+ \bar{f}_{0}(x)\epsilon^{2}(x, D_{x})f_{0}(x) - \bar{f}_{0}(x) v^{2}(x) f_{0}(x) \d x. We consider the situation when the energy is not positive. In this case the flow cannot be written as a unitary group on a Hilbert space, and the Klein-Gordon equation may have complex eigenfrequencies. Using the theory of definitizable operators on Krein spaces and time-dependent methods, we prove the existence and completeness of wave operators, both in the short- and long-range cases. The range of the wave operators are characterized in terms of the spectral theory of the generator, as in the usual Hilbert space case

Making Neural Networks Interpretable with Attribution: Application to Implicit Signals Prediction

Explaining recommendations enables users to understand whether recommended items are relevant to their needs and has been shown to increase their trust in the system. More generally, if designing explainable machine learning models is key to check the sanity and robustness of a decision process and improve their efficiency, it however remains a challenge for complex architectures, especially deep neural networks that are often deemed "black-box". In this paper, we propose a novel formulation of interpretable deep neural networks for the attribution task. Differently to popular post-hoc methods, our approach is interpretable by design. Using masked weights, hidden features can be deeply attributed, split into several input-restricted sub-networks and trained as a boosted mixture of experts. Experimental results on synthetic data and real-world recommendation tasks demonstrate that our method enables to build models achieving close predictive performances to their non-interpretable counterparts, while providing informative attribution interpretations.Comment: 14th ACM Conference on Recommender Systems (RecSys '20

Acute sleep deprivation increases portion size and affects food choice in young men

SummaryAcute sleep loss increases food intake in adults. However, little is known about the influence of acute sleep loss on portion size choice, and whether this depends on both hunger state and the type of food (snack or meal item) offered to an individual. The aim of the current study was to compare portion size choice after a night of sleep and a period of nocturnal wakefulness (a condition experienced by night-shift workers, e.g. physicians and nurses). Sixteen men (age: 23±0.9 years, BMI: 23.6±0.6kg/m2) participated in a randomized within-subject design with two conditions, 8-h of sleep and total sleep deprivation (TSD). In the morning following sleep interventions, portion size, comprising meal and snack items, was measured using a computer-based task, in both fasted and sated state. In addition, hunger as well as plasma levels of ghrelin were measured. In the morning after TSD, subjects had increased plasma ghrelin levels (13%, p=0.04), and chose larger portions (14%, p=0.02), irrespective of the type of food, as compared to the sleep condition. Self-reported hunger was also enhanced (p<0.01). Following breakfast, sleep-deprived subjects chose larger portions of snacks (16%, p=0.02), whereas the selection of meal items did not differ between the sleep interventions (6%, p=0.13). Our results suggest that overeating in the morning after sleep loss is driven by both homeostatic and hedonic factors. Further, they show that portion size choice after sleep loss depend on both an individual's hunger status, and the type of food offered