cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Towards engineering rhodococcus for biodiesel production from lignin
Creators: name: Somani, Hannah
Publisher: name: Imperial College London
Year: 2018

description: There is a pressing need for sustainable liquid transportation fuels to address climate change concerns and meet increasing global energy demand. Biofuels offer a low carbon alternative to fossil fuels, and microbial biodiesel has the potential to play a key role in their future. This thesis first assesses the economic and environmental considerations associated with producing biodiesel from lignin on a large scale. The analysis concludes that it could be commercially viable by sourcing underutilised waste lignin as a feedstock and using existing pulp mill or biorefinery infrastructure in the process, bringing costs in line with current cellulosic bioethanol production at around $140 per barrel of oil equivalent. Based on this conclusion the oleaginous bacteria Rhodococcus opacus PD630 was then selected to explore the potential use of this genus of microorganisms to carry out this process. We demonstrate its capacity to metabolise, and accumulate intracellular lipids, when provided with lignin breakdown model compounds as a sole carbon source under nitrogen limiting conditions. Cells reached 22% lipid content (dry weight) after 36 hours when grown on 4-hydroxybenzoic acid, 14% after 48 hours on vanillic acid and were able to grow on, but not synthesise lipids from, vanillin. Although this demonstrated that the strain could use lignin breakdown products for lipid biosynthesis it was unable use untreated Kraft lignin for this purpose. To remedy this we sought to express the DypB lignin peroxidase from the ligninolytic strain, R. jostii RHA1, in R. opacus PD630 to catalyse depolymerisation. Attempts at plasmid construction, cloning and protein expression were challenging, and creating a single organism able to perform the whole bioconversion pathway proved elusive. A mixed enzymatic and microbial approach using T. versicolor laccase was more successful. The laccase catalysed lignin depolymerisation, in the presence of syringaldehyde as a redox mediator, allowing R. opacus PD630 to metabolise the breakdown products and accumulate lipids. A 96-hour depolymerisation reaction followed by fermentation yielded 20% cell lipid content after 60 hours. Combining these steps into a simultaneous process slowed culture growth, but cells reached a higher lipid content of 23% after 72 hours. These results demonstrate that a mixed approach of enzymatic lignin depolymerisation and microbial fermentation is a potential route for converting waste lignin, a renewable feedstock, into biodiesel, a sustainable alternative to fossil fuels.
Fast Adaptive Non-Monotone Submodular Maximization Subject to a Knapsack Constraint
Creators: name: Amanatidis, Georgios
name: Fusco, Federico
name: Lazos, Philip
name: Leonardi, Stefano
name: Reiffenhäuser, Rebecca
Publisher: name: arXiv
Year: 2020
Subjects: subject: Data Structures and Algorithms (cs.DS)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: Constrained submodular maximization problems encompass a wide variety of applications, including personalized recommendation, team formation, and revenue maximization via viral marketing. The massive instances occurring in modern day applications can render existing algorithms prohibitively slow, while frequently, those instances are also inherently stochastic. Focusing on these challenges, we revisit the classic problem of maximizing a (possibly non-monotone) submodular function subject to a knapsack constraint. We present a simple randomized greedy algorithm that achieves a $5.83$ approximation and runs in $O(n \log n)$ time, i.e., at least a factor $n$ faster than other state-of-the-art algorithms. The robustness of our approach allows us to further transfer it to a stochastic version of the problem. There, we obtain a 9-approximation to the best adaptive policy, which is the first constant approximation for non-monotone objectives. Experimental evaluation of our algorithms showcases their improved performance on real and synthetic data.
description: Same as v1. Version 2 was a replacement intended for arXiv:2102.08327 and erroneously updated here
Randomized Value Functions via Multiplicative Normalizing Flows
Creators: name: Touati, Ahmed
name: Satija, Harsh
name: Romoff, Joshua
name: Pineau, Joelle
name: Vincent, Pascal
Publisher: name: arXiv
Year: 2018
Subjects: subject: Machine Learning (cs.LG)
subject: Machine Learning (stat.ML)
subject: FOS: Computer and information sciences

description: Randomized value functions offer a promising approach towards the challenge of efficient exploration in complex environments with high dimensional state and action spaces. Unlike traditional point estimate methods, randomized value functions maintain a posterior distribution over action-space values. This prevents the agent's behavior policy from prematurely exploiting early estimates and falling into local optima. In this work, we leverage recent advances in variational Bayesian neural networks and combine these with traditional Deep Q-Networks (DQN) and Deep Deterministic Policy Gradient (DDPG) to achieve randomized value functions for high-dimensional domains. In particular, we augment DQN and DDPG with multiplicative normalizing flows in order to track a rich approximate posterior distribution over the parameters of the value function. This allows the agent to perform approximate Thompson sampling in a computationally efficient manner via stochastic gradient methods. We demonstrate the benefits of our approach through an empirical comparison in high dimensional environments.
Steps toward the power spectrum of matter. I.The mean spectrum of galaxies
Creators: name: Einasto, J.
name: Einasto, M.
name: Tago, E.
name: Starobinsky, A. A.
name: Atrio-Barandela, F.
name: M"uller, V.
name: Knebe, A.
name: Frisch, P.
name: Cen, R.
name: Andernach, H.
name: Tucker, D.
Publisher: name: arXiv
Year: 1998
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We calculate the mean power spectrum of galaxies using published power spectra of galaxies and clusters of galaxies. On small scales we use the power spectrum derived from the 2-dimensional distribution of APM galaxies, on large scales we use power spectra derived from 3-dimensional data for galaxy and cluster samples. Spectra are reduced to real space and to the amplitude of the power spectrum of APM galaxies. Available data indicate the presence of two different populations in the nearby Universe. Clusters of galaxies sample a relatively large region in the Universe where rich, medium and poor superclusters are well represented. Their mean power spectrum has a spike on scale 120 h^{-1}Mpc, followed by an approximate power-law spectrum of index n = -1.9 towards small scales. The power spectrum found from LCRS and IRAS 1.2 Jy surveys is flatter around the maximum, which may represent regions of the Universe with medium-rich and poor superclusters.
description: LaTex (sty files added), 35 pages, 5 PostScript figures and Table with mean power spectrum embedded, Astrophysical Journal (accepted)
Analytic and numerical analysis of the cosmic 21cm signal
Creators: name: Schmit, Claude
Publisher: name: Imperial College London
Year: 2018

description: Cosmology in the 21st century has matured into a precision science. Measurements of the cosmic microwave background, galaxy surveys, weak lensing studies and supernovae surveys all but confirm that we live in a geometrically flat Universe dominated by a dark energy component where most of the matter is dark. Yet, challenges to this model remain as well as periods in its evolution unobserved at present. The next decade will see the construction of a new generation of telescopes poised to answer some of these remaining questions and peer into unseen depths. Because of the technological advances of the previous decades and the scale of the new generation of telescopes, for the first time, cosmology will be constrained through the observation of the cosmic 21cm signal emitted by hydrogen atoms across the Universe. Being the ubiquitous element present throughout the different evolutionary stages of the Universe, neutral hydrogen holds great potential to answer many of the remaining challenges which face cosmology today. In the context of 21cm radiation, we identify two approaches which will increase the information gain from future observations, a numerical as well as an analytic approach. The numerical challenges of future analyses are a consequence of the data rates of next generation telescopes, and we address this here introducing machine learning techniques as a possible solution. Artificial neural networks have gained much attention in both the scientific and commercial world, and we apply one such network here as a way to emulate numerical simulations necessary for parameter inference from future data. Further, we identify the potential of the bispectrum, the Fourier transform of the three-point statistic, as a cosmological probe in the context of low redshift 21cm intensity mapping experiments. This higher order statistical analysis can constrain cosmological parameters beyond the capabilities of CMB observations and power spectrum analyses of the 21cm signal. Lastly, we focus on a fully 3D expansion of the 21cm power spectrum in the natural spherical basis for large angle observations, drawing on the success of the technique in weak lensing studies.
Comparing two models for measuring the neutron star equation of state from gravitational-wave signals
Creators: name: Carney, Matthew F.
name: Wade, Leslie E.
name: Irwin, Burke S.
Publisher: name: arXiv
Year: 2018
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Observations of gravitational-wave signals from binary neutron-star mergers, like GW170817, can be used to constrain the neutron-star equation of state (EoS). One method involves modeling the EoS and measuring the model parameters through Bayesian inference. A previous study has demonstrated the effectiveness of using a phenomenologically parameterized piecewise polytrope to extract constraining information from a simulated population of binary neutron-star mergers. Despite its advantages compared to more traditional methods of measuring the tidal deformability of neutron stars, notable deficiencies arise when using this EoS model. In this work, we describe in detail the implementation of a model built from a spectral decomposition of the adiabatic index that was used by the LIGO-Virgo Collaboration in to constrain the neutron star EoS from GW170817. We demonstrate its overall consistency in recovering the neutron star EoS from a simulated signal to the piecewise polytropic implementation used in and explain any differences that arise. We find that both models recover consistent tidal information from the simulate signals with tightest constraints on the EoS around twice nuclear saturation density. As expected, the statistical error that arises in the piecewise polytropic representation near the fixed joining densities is greatly reduced by using the spectral model. In addition, we find that our choice of prior can have a dominant effect on EoS constraints
Macroplastic Debris Transfer in Rivers: A Travel Distance Approach
Creators: name: Newbould, Robert
Publisher: name: University of Leicester
Year: 2021
Subjects: Uncategorized

description: Plastic accumulation in the marine environment is a major concern given the harmful effects and longevity of plastics at sea. To understand and mitigate this accumulation, an understanding of plastic transport in rivers and estimates of riverine plastic flux are required (since rivers are potentially significant transport pathways of plastic debris to the oceans). Existing methods to investigate plastic transport in rivers and to estimate riverine plastic flux (from field measurements and modelling efforts) are, however, very crude, subject to a high degree of uncertainty and (perhaps most importantly) fail to consider the processes controlling displacement. Here, a new and fundamentally different approach to investigating plastic transport in rivers is presented, which considers the travel distances of individual items of macroplastic debris (and thus, the processes controlling displacement). This approach combines an experimental component, in which macroplastic tracers were tracked in a small river reach, with the construction of a numerical model, which is intended to act as an interpretive conceptual framework. Macroplastic travel distances were found to be low and variable and the travel distance distribution was systematically controlled by the location and characteristics of ‘trapping points’ (particularly overhanging trees and meander bends). The numerical model was based on ‘the probability of trapping’ and described particle displacement distributions reasonably well. Although significant knowledge gaps remain (which require further investigation), the tracer experiment results and outputs from the numerical model demonstrated the feasibility of using a travel distance approach to understand and predict plastic transfer in rivers. This approach also has the potential to improve riverine plastic flux estimates.
Angiotensin II type 2 receptor signalling promotes glioblastoma growth: A novel target for therapeutic intervention
Creators: name: Renziehausen, Alexander Wilhelm Jay
Publisher: name: Imperial College London
Year: 2017

description: The renin-angiotensin system (RAS) is a major homeostatic regulator of salt-water equilibrium, intravascular volume and blood pressure. Aside from its importance in normal physiology, locally expressed components of this system are increasingly being implicated in numerous diverse pathologies, including cancer. However, the role of angiotensin signalling and its potential for therapeutic intervention remain largely unexplored in glioblastoma (GBM). This study set out to investigate the functions of the angiotensin II type 1 and type 2 receptors (AT1R and AT2R) in GBM and determine whether clinically approved drugs that target these receptors could be repurposed as novel therapeutics. To this end several GBM cell lines, patient derived primary cell cultures and stem-like cells (GSCs) were profiled for angiotensin receptor gene expression and interrogated in functional assays using angiotensin II or receptor-specific antagonists. This is the first report that inhibition of AT2R significantly reduces GBM cell growth, migration and the ability of these cells to induce angiogenesis under serum-starved conditions. This was particularly evident when GBM cells expressing this receptor were treated with the AT2R antagonist EMA401, which is currently under clinical development for the treatment of neuropathic pain. RNA-sequencing studies revealed that blocking AT2R leads to significant differential expression of numerous genes linked to pathways important in cancer, particularly upregulation of putative tumour suppressor genes such as RPH3AL or DUSP2 and downregulation of genes known to enhance tumour cell survival such as TRPV6 or ALDH3A1. Contrary to previous reports in other cancer types, inhibition of AT1R had no direct effect on the growth of GBM cells, despite significantly limiting their ability to induce angiogensis in vitro. Together these findings demonstrate that AT2R is the main angiotensin receptor supporting GBM growth and that its inhibition is a novel therapeutic strategy that warrants pre-clinical testing.
A Regret Analysis of Bilateral Trade
Creators: name: Cesa-Bianchi, Nicolò
name: Cesari, Tommaso
name: Colomboni, Roberto
name: Fusco, Federico
name: Leonardi, Stefano
Publisher: name: arXiv
Year: 2021
Subjects: subject: Machine Learning (cs.LG)
subject: Theoretical Economics (econ.TH)
subject: Machine Learning (stat.ML)
subject: FOS: Computer and information sciences
subject: FOS: Economics and business

description: Bilateral trade, a fundamental topic in economics, models the problem of intermediating between two strategic agents, a seller and a buyer, willing to trade a good for which they hold private valuations. Despite the simplicity of this problem, a classical result by Myerson and Satterthwaite (1983) affirms the impossibility of designing a mechanism which is simultaneously efficient, incentive compatible, individually rational, and budget balanced. This impossibility result fostered an intense investigation of meaningful trade-offs between these desired properties. Much work has focused on approximately efficient fixed-price mechanisms, i.e., Blumrosen and Dobzinski (2014; 2016), Colini-Baldeschi et al. (2016), which have been shown to fully characterize strong budget balanced and ex-post individually rational direct revelation mechanisms. All these results, however, either assume some knowledge on the priors of the seller/buyer valuations, or a black box access to some samples of the distributions, as in D{ü}tting et al. (2021). In this paper, we cast for the first time the bilateral trade problem in a regret minimization framework over rounds of seller/buyer interactions, with no prior knowledge on the private seller/buyer valuations. Our main contribution is a complete characterization of the regret regimes for fixed-price mechanisms with different models of feedback and private valuations, using as benchmark the best fixed price in hindsight. More precisely, we prove the following bounds on the regret:
 $\bullet$ $\widetildeΘ(\sqrt{T})$ for full-feedback (i.e., direct revelation mechanisms);
 $\bullet$ $\widetildeΘ(T^{2/3})$ for realistic feedback (i.e., posted-price mechanisms) and independent seller/buyer valuations with bounded densities;
 $\bullet$ $Θ(T)$ for realistic feedback and seller/buyer valuations with bounded densities;
 $\bullet$ $Θ(T)$ for realistic feedback and independent seller/buyer valuations;
 $\bullet$ $Θ(T)$ for the adversarial setting.
CARE Project Briefing July 2018
Creators: name: Martin, Melanie
Publisher: name: figshare
Year: 2018
Subjects: subject: 160102 Biological (Physical) Anthropology
subject: FOS: Sociology
subject: 111799 Public Health and Health Services not elsewhere classified
subject: FOS: Health sciences
subject: 111708 Health and Community Services

description: Project briefing presented to the Community Health Center and Community Planning Development Office of Barrio Namqom, Formosa Argentina in July 2018. Discusses results from published studies on early pubertal development and factors associated with cesarean section deliveries in Namqom families. Data collection was carried out from 2011-2015 by the Chaco Area Reproductive Ecology Project.
Steps toward the power spectrum of matter. II. The biasing correction with sigma_8 normalization
Creators: name: Einasto, J.
name: Einasto, M.
name: Tago, E.
name: M"uller, V.
name: Knebe, A.
name: Cen, R.
name: Starobinsky, A. A.
name: Atrio-Barandela, F.
Publisher: name: arXiv
Year: 1998
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: A new method to determine the bias parameter of galaxies relative to matter is suggested. The method is based on the assumption that gravity is the dominating force which determines the formation of the structure in the Universe. Due to gravitational instability the galaxy formation is a threshold process: in low-density environments galaxies do not form and matter remains in primordial form. We investigate the influence of the presence of void and clustered populations to the power spectrum of matter and galaxies. The power spectrum of galaxies is similar to the power spectrum of matter; the fraction of total matter in the clustered population determines the difference between amplitudes of fluctuations of matter and galaxies, i.e. the bias factor. To determine the fraction of matter in voids and clustered population we perform numerical simulations. The fraction of matter in galaxies at the present epoch is found using a calibration through the sigma_8 parameter.
description: LaTex (sty files added), 31 pages, 4 PostScript figures embedded, Astrophysical Journal (accepted)
Transitions Project study briefing
Creators: name: Martin, Melanie
Publisher: name: figshare
Year: 2018
Subjects: subject: 160102 Biological (Physical) Anthropology
subject: FOS: Sociology
subject: 111799 Public Health and Health Services not elsewhere classified
subject: FOS: Health sciences
subject: 111708 Health and Community Services

description: Project briefing presented to the Community Health Center and Community Planning Development Office of Barrio Namqom, Formosa Argentina in July 2018. Discusses results from published studies on early pubertal development and factors associated with cesarean section deliveries in Namqom families. Data collection was carried out from 2011-2015 by the Chaco Area Reproductive Ecology Project.
Steps toward the power spectrum of matter. III. The primordial spectrum
Creators: name: Einasto, J.
name: Einasto, M.
name: Tago, E.
name: Starobinsky, A. A.
name: Atrio-Barandela, F.
name: M"uller, V.
name: Knebe, A.
name: Cen, R.
Publisher: name: arXiv
Year: 1998
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Observed power spectrum of matter found in Papers I and II is compared with analytical power spectra. Spatially flat cold and mixed dark matter models with cosmological constant and open models are considered. The primordial power spectrum of matter is determined using the power spectrum of matter and the transfer functions of analytical models. The primordial power spectrum has a break in amplitude. We conclude that a scale-free primordial power spectrum is excluded if presently available data on the distribution of clusters and galaxies represent the true mass distribution of the Universe.
description: LaTex (sty files added), 22 pages, 5 PostScript figures embedded, Astrophysical Journal (accepted)
Visual maps between coarsely convex spaces
Creators: name: Ezawa, Yuuhei
name: Fukaya, Tomohiro
Publisher: name: arXiv
Year: 2021
Subjects: subject: Metric Geometry (math.MG)
subject: Geometric Topology (math.GT)
subject: FOS: Mathematics
subject: Primary 53C23, Secondary 20F67, 20F65, 20F69

description: The class of coarsely convex spaces is a coarse geometric analogue of the class of nonpositively curved Riemannian manifolds. It includes Gromov hyperbolic spaces, CAT(0) spaces, proper injective metric spaces and systolic complexes. It is well known that quasi-isometric embeddings of Gromov hyperbolic spaces induce topological embeddings of their boundaries. Dydak and Virk studied maps between Gromov hyperbolic spaces which induce continuous maps between their boundaries. In this paper, we generalize their work to maps between coarsely convex spaces.
description: 33 pages
Prestressed cold-formed steel beams
Creators: name: Hadjipantelis, Nicolaos
Publisher: name: Imperial College London
Year: 2018

description: A novel concept, whereby prestressing techniques are utilised to enhance the load-carrying capacity and serviceability performance of cold-formed steel beams, is proposed. The prestressing is applied by means of a high-strength steel cable located within the bottom hollow flange of the cold-formed steel beam at an eccentric location with respect to its strong geometric axis. Since the initial stresses generated by the prestressing are opposite in sign to those induced during the subsequent imposed vertical loading stage, the development of instabilities is delayed and thus the capacity of the cold-formed steel beam is enhanced. Owing to the pre-camber that is induced along the member during the prestressing stage and the contribution of the cable to the system bending stiffness, the overall vertical deflections of the member are reduced significantly. Prestressed cold-formed steel beams can provide highly-efficient structural solutions. Owing to their enhanced structural performance, for a given span and imposed vertical load, a smaller cross-section is required and thus a more lightweight solution is achievable. Potentially, the proposed beams can open up new applications for cold-formed steel in construction, particularly in cases where increased load-carrying capacities, longer spans and reduced deflections are desired. The current thesis presents the conceptual development of prestressed cold-formed steel beams. The mechanical behaviour of the proposed structural system is explored using analytical and numerical models with the origin of the obtained structural benefits being demonstrated. Finite element modelling is employed to simulate the behaviour of the proposed beams during the prestressing and imposed vertical loading stages and parametric studies are conducted to investigate the influence of the key controlling parameters, such as the prestress level, cable size, section slenderness and centroid location. Finally, design recommendations and failure criteria, which define the permissible design zone for the prestressed system, are developed with their implementation being demonstrated through practical a worked example.
title: ADCO, Comptes du Petit-Cîteaux (1477-1491) (11 H 1179), f. 00637
Creators: name: de la Côte d'Or, Archives départementales
name: Archives Départementales De La Côte D'Or
name: Petot, Frédérique
name: Projet CBMA
name: CBMA/CG21/F.PETOT/2019
name: Petot, Frédéric
name: Archives Départementales De La Côte-D'Or
Publisher: name: NAKALA - https://nakala.fr (Huma-Num - CNRS)
publisherIdentifier: https://ror.org/04ces3204
publisherIdentifierScheme: ROR
Year: 2020
Subjects: subject: LaMOP
subject: Laboratoire de Médiévistique Occidentale de Paris
subject: cartulaire
subject: comptes
subject: Corpus Burgundiae Medii Aevi
subject: Chartes de la Bourgogne du Moyen Âge

description: Comptes du Petit-Cîteaux (1477-1491), Archives départementales de la Côte-d'Or, (11 H 1179). Numérisation en mode image.
description: Relation: http://www.cbma-project.eu/
description: Bibliographic citation: Comptes du Petit-Cîteaux (1477-1491), Archives départementales de la Côte-d'Or, (11 H 1179), f. 00637, in Projet CBMA - Corpus Burgundiae Medii Aevi [Ressource en ligne], https://manuscrits.cbma-project.eu/
description: Provenance: https://www.geonames.org/3024876
description: Provenance: http://www.idref.fr/030974844/id
description: Provenance: https://catalogue.bnf.fr/ark:/12148/cb12228351v
description: Provenance: abbaye de Cîteaux
description: Provenance: http://www.wikidata.org/entity/Q843261
On (signed) Takagi-Landsberg functions: $p^{\text{th}}$ variation, maximum, and modulus of continuity
Creators: name: Mishura, Yuliya
name: Schied, Alexander
Publisher: name: arXiv
Year: 2018
Subjects: subject: Probability (math.PR)
subject: FOS: Mathematics
subject: 28A80, 26A30, 26A27, 60G17, 60H05, 26A15, 26A16

description: We study a class $\mathfrak X^H$ of signed Takagi-Landsberg functions with Hurst parameter $H\in(0,1)$. We first show that the functions in $\mathfrak X^H$ admit a linear $p^{\text{th}}$ variation along the sequence of dyadic partitions of $[0,1]$, where $p=1/H$. The slope of the linear increase can be represented as the $p^{\text{th}}$ absolute moment of the infinite Bernoulli convolution with parameter $2^{H-1}$. The existence of a continuous $p^{\text{th}}$ variation enables the use of the functions in $\mathfrak X^H$ as test integrators for higher-order pathwise Itô calculus. Our next results concern the maximum, the maximizers, and the modulus of continuity of the classical Takagi-Landsberg function for all $0
Evidence for Temperature Chaos in Spin Glasses
Creators: name: Zhai, Qiang
name: Orbach, Raymond L.
name: Schlagel, Deborah
Publisher: name: arXiv
Year: 2020
Subjects: subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: We study the field cooled magnetization of a CuMn spin glass under temperature perturbations. The $T$-cycling curves are compared with the reference curve without temperature cycling. There is a crossover from the cumulative aging region to noncumulative aging region as the temperature change is increased. The cumulative aging range scales with the chaos length $\ell_\mathrm{c}$, becoming comparable to the correlation length, $ξ$, at the crossover boundary. The extracted chaos exponent, $ζ= 1.1$, is in agreement with theoretical predictions. Our results strongly suggest temperature chaos exists in real spin glasses system.
Spatially-resolved and temporally-explicit global wind energy potentials as inputs to assessment models
Creators: name: Bosch, Jonathan
Publisher: name: Imperial College London
Year: 2018

description: Several decarbonisation scenarios indicate that renewable energy will be a key supply route to mitigate carbon emissions this century. To better represent the implications of such an energy transition, it is important that energy systems models (ESMs) can realistically characterise the technical and economic potential of renewable energy resources. This thesis presents a temporally-explicit and geospatially-resolved methodology for estimating the global wind energy potential, i.e. the annual terawatt-hour (TWh/yr) production potential of wind farms, assuming that capacity could be built across the viable onshore and offshore areas of each country, globally. Further, a geospatially-resolved levelised cost of electricity (LCOE) model is developed to characterise the offshore cost potential, accounting for non-resource related cost factors. Capacity potential is produced in tranches according to the average annual capacity factor and the capacity factor in each time slice. For offshore wind, capacity potential is also disaggregated by the distance to shore and water depth, which are the main cost drivers. A technology-rich description of fixed and floating foundation types allows LCOEs to be calculated for each grid cell across the globe, relative to location-specific annual energy production (AEP). Results show that the global wind energy potential is vast, but severely diminished if areas far from electricity infrastructure are discounted. Nevertheless, for onshore wind the capacity potential for capacity factors above 15% is 267 TW, with a generation potential of 580,000 TWh/yr. The offshore potential is 329,600 TWh/yr with a relatively smaller deployment capacity of 85.6 TW, reflecting the access to higher capacity factors in offshore areas. Deployment potential is favourable for countries with large shallow water areas. However, recent cost developments have made access to transitional and deep water locations much more feasible as long as turbine size increases continue to offset the relatively higher foundation costs.
$α$-Expansions with odd partial quotients
Creators: name: Boca, Florin P.
name: Merriman, Claire
Publisher: name: arXiv
Year: 2018
Subjects: subject: Dynamical Systems (math.DS)
subject: FOS: Mathematics
subject: 37E05, 11J70, 11K50, 37A35

description: We consider an analogue of Nakada's $α$-continued fraction transformation in the setting of continued fractions with odd partial quotients. More precisely, given $α\in [\frac{1}{2}(\sqrt{5}-1),\frac{1}{2}(\sqrt{5}+1)]$, we show that every irrational number $x\in I_α=[α-2,α)$ can be uniquely represented as $$ x= \cfrac{e_1 (x;α)}{d_1 (x;α) +\cfrac{e_2(x;α)}{d_2(x;α)+\cdots}} , $$ with $e_i(x;α) \in \{ \pm 1\}$ and $d_i(x;α) \in 2{\mathbb N} -1$ determined by the iterates of the transformation $$φ_α(x) := \frac{1}{| x|} - 2 \bigg[ \frac{1}{2| x|} +\frac{1-α}{2} \bigg]-1$$ of $I_α$. We also describe the natural extension of $φ_α$ and prove that the endomorphism $φ_α$ is exact.
description: a few typos corrected in the published version
Entanglement and quantum clocks in curved spacetime
Creators: name: Lock, Maximilian
Publisher: name: Imperial College London
Year: 2018

description: In this thesis, we investigate how motion through a curved spacetime background affects a system's dynamics, specifically the entanglement contained between its degrees of freedom, and our ability to use the system as a clock. We incorporate both quantum theory and general relativity using quantum field theory in curved spacetime, localising the field by boundaries to describe e.g. an optical cavity. We derive the effect of boundary motion on the state of the field contained therein. A moving boundary can create particles from the vacuum in a phenomenon known as the dynamical Casimir effect; we give a description of the effect in curved spacetime. Reconsidering a common scenario, now adopting the Schwarzschild metric, we find novel particle-production resonances due to the curvature. We also discuss a potential enhancement of the effect in the phonon field of a Bose-Einstein condensate. We apply these results to a quantum model of the famous light-clock thought experiment. After motivating and reviewing the model, we show for Gaussian clock states that the discrepancy between two such clocks is state-independent, and separates into classical and quantum effects. We numerically investigate the discrepancy when one clock is held in a gravitational field and the other falls a certain distance, finding quantitative and qualitative differences from the case of classical pointlike observers. We further show that the quantum and classical effects respectively increase and decrease in magnitude with increasing gravitational field strength. We then study entanglement in a number of drop-tower scenarios, considering entanglement generated between field modes within an apparatus, and the degradation of an initially entangled state, both between spatially separated parties, and between modes contained within one apparatus. We quantify the effect via the negativity or the entanglement fidelity, as appropriate to each case. We present numerical investigations into the entanglement generated/degraded, finding novel features compared to previous investigations of non-inertial motion in flat spacetime, and discuss our results in the context of recent experiments on the subject.
A Digital Moral Framework for Australian Secondary Schools
Creators: name: JOHN BELLAVANCE
Publisher: name: Monash University
Year: 2018
Subjects: Education

description: This study investigated how the moral domains of moral reasoning, moral emotion and moral behaviour mediated the use of information and communication technologies (ICTs) by a small group of secondary school students aged 15-16 years old. The study’s main aim was to provide further understanding of adolescents’ moral development, taking into consideration the relationship between morality, ICTs and pedagogy. The first outcome of the study is a Digital Moral Framework (DMF) that parents and teachers can use to foster moral practices and address moral challenges faced by secondary school students while using ICTs. The DMF outlines some moral values and abilities that can mediate the use of ICTs. The second outcome is the Cyber Values Systems model (CVS) that can be used to analyse and understand the role of values in in the use of ICTs by young people.
Learning Graph Laplacian with MCP
Creators: name: Zhang, Yangjing
name: Toh, Kim-Chuan
name: Sun, Defeng
Publisher: name: arXiv
Year: 2020
Subjects: subject: Machine Learning (cs.LG)
subject: Optimization and Control (math.OC)
subject: FOS: Computer and information sciences
subject: FOS: Mathematics

description: We consider the problem of learning a graph under the Laplacian constraint with a non-convex penalty: minimax concave penalty (MCP). For solving the MCP penalized graphical model, we design an inexact proximal difference-of-convex algorithm (DCA) and prove its convergence to critical points. We note that each subproblem of the proximal DCA enjoys the nice property that the objective function in its dual problem is continuously differentiable with a semismooth gradient. Therefore, we apply an efficient semismooth Newton method to subproblems of the proximal DCA. Numerical experiments on various synthetic and real data sets demonstrate the effectiveness of the non-convex penalty MCP in promoting sparsity. Compared with the existing state-of-the-art method, our method is demonstrated to be more efficient and reliable for learning graph Laplacian with MCP.
description: 32 pages
Linking Lie groupoid representations and representations of infinite-dimensional Lie groups
Creators: name: Amiri, Habib
name: Schmeding, Alexander
Publisher: name: arXiv
Year: 2018
Subjects: subject: Group Theory (math.GR)
subject: Representation Theory (math.RT)
subject: FOS: Mathematics
subject: 22E66 (primary), 22E65, 22A22, 58D15 (secondary)

description: The present paper links the representation theory of Lie groupoids and infinite-dimensional Lie groups. We show that smooth representations of Lie groupoids give rise to smooth representations of associated Lie groups. The groups envisaged here are the bisection group and a group of groupoid self maps. Then representations of the Lie groupoids give rise to representations of the infinite-dimensional Lie groups on spaces of (compactly supported) bundle sections. Endowing the spaces of bundle sections with a fine Whitney type topology, the fine very strong topology, we even obtain continuous and smooth representations. It is known that in the topological category, this correspondence can be reversed for certain topological groupoids. We extend this result to the smooth category under weaker assumptions on the groupoids.
description: 33 pages, v2: Corrected numerous typos and some small mistakes, small rewrite to improve readability, main results remain unchanged
Improvements to the Montel-Carathéodory Theorem for families of $\mathbb{P}^n$-valued holomorphic curves
Creators: name: Datt, Gopal
Publisher: name: arXiv
Year: 2020
Subjects: subject: Complex Variables (math.CV)
subject: FOS: Mathematics
subject: 32A19, 30D45, 32A22

description: In this paper, we establish various sufficient conditions for a family of holomorphic mappings on a domain $D\subseteq\mathbb{C}$ into $\mathbb{P}^n$ to be normal. Our results are improvements to the Montel-Carathéodory Theorem for a family of $\mathbb{P}^n$-valued holomorphic curves.
The internal structure of the Uranian satellites:a preliminary note
Creators: name: Celebonovic, V.
Publisher: name: arXiv
Year: 1998
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Preliminary results of a theoretical determination of the basic parameters of the internal structure of the five Uranian satellies are presented.
description: PDF file,no figures
The Radio-to-Submm Spectral Index as a Redshift Indicator
Creators: name: Carilli, C. L.
name: Yun, Min Su
Publisher: name: arXiv
Year: 1998
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present models of the 1.4 GHz to 350 GHz spectral index, alpha(350/1.4), for starburst galaxies as a function of redshift. The models include a semi-analytic formulation, based on the well quantified radio-to-far infrared correlation for low redshift star forming galaxies, and an empirical formulation, based on the observed spectrum of the starburst galaxies M82 and Arp 220. We compare the models to the observed values of alpha(350/1.4) for starburst galaxies at low and high redshift. We find reasonable agreement between the models and the observations, and in particular, that an observed spectral index of alpha(350/1.4) > +0.5 indicates that the target source is likely to be at high redshift, z > 1. The evolution of alpha(350/1.4) with redshift is mainly due to the very steep rise in the Raleigh-Jeans portion of the thermal dust spectrum shifting into the 350 GHz band with increasing redshift. We also discuss situations where this relationship could be violated. We then apply our models to examine the putative identifications of submm sources in the Hubble Deep Field, and conclude that the submm sources reported by Hughes et al. are likely to be at high redshifts, z > 1.5.
description: standard LATEX file plus 1 postscript figure. Added references and revised figure. second figure revision. Final Proof version. to appear in Astrophysical Journal Letters
The immunomodulatory effects of nociceptin – development and validation of a biosensor assay
Creators: name: Hebbes, Christopher
Publisher: name: University of Leicester
Year: 2021
Subjects: Uncategorized

description: Opioids have long been associated with increased susceptibility to infectious diseases, and the role of the classical opioids in immunomodulation is a subject of some debate. A fourth opioid-like receptor, sharing significant sequence homology, and Gi mechanism, to the classical MOP, DOP and KOP opioid receptors has emerging evidence for its expression throughout the immune system. Furthermore, observational evidence suggests that the concentration of nociceptin, the endogenous agonist for this receptor increases in the human plasma, synovial fluid and sputum sampled in the context of inflammatory conditions. Administration of exogenous nociceptin worsens mortality in an animal model of sepsis, further suggestive that this non-classical opioid may have an immunomodulatory role in-vivo.Despite limited observational evidence, localising the source of the increased nociceptin concentration has been challenging, because of its low concentration and problems with existing use of ELISA and RIA tests. Chimeric G-proteins facilitate non-classical coupling between intracellular pathways, allowing the use of new markers as a readout of receptor activation, and therefore local detection of agonist ligands and their concentration.This work validated the design of a chimeric G-protein based biosensor test to detect nociceptin release from a single cell. In principle, the biosensor facilitated nociceptin receptor coupling via Gq to calcium flux for a non-invasive and non-radioactive readout of receptor activation. The validated test was used to investigate nociceptin release from immunocytes (and subtypes) from healthy individuals and patients admitted to the intensive care unit with sepsis. These data were correlated with additional PCR and immunohistochemistry tests to determine expression of nociceptin, its receptor and their precursors.In general, mixed granulocytes were found to release nociceptin. In evaluating immunocyte subsets, both nociceptin and its receptor are found in eosinophils and neutrophils from individuals with sepsis, and when incubated in an environment mimicking sepsis, suggesting upregulation of this system in sepsis.
title: Dissociating the Disruptive Effects of Irrelevant Music and Speech on Serial Recall of Tonal and Verbal Sequences
Creators: name: Kattner, Florian
name: Meinhardt, Hanna
Publisher: name: Frontiers
Year: 2020

description: Task-irrelevant speech or music sounds are known to disrupt verbal short-term memory even when participants are instructed to ignore the sound, suggesting that automatically processed acoustical changes interfere with the rehearsal of phonological items. However, much less is known about auditory distraction in tasks that require the memorization and recall of non-phonological auditory items. In the present study, both musically trained and untrained participants were asked to memorize random tone sequences (consisting of low, medium, and high pitch tones) while task-irrelevant sound was presented. Irrelevant instrumental music was found to produce more disruption of tonal recall than white noise, whereas irrelevant speech produced intermediate levels of disruption. In contrast, only speech produced significant interference in an analogous verbal recall task. Crucially, although musically trained participants were able to recall more tones in general, the degree of auditory distraction that was produced by irrelevant music in the tonal recall task was found to be independent of musical expertise. The findings are in line with the assumption of two separate mechanisms for the maintenance of tonal and phonological information. Specifically, short-term memory for tone sequences may rely on a pitch-based rehearsal system which is disrupted by the perception of irrelevant pitch changes as contained in instrumental music (and to a lesser extent in speech), whereas serial recall of verbal items is most sensitive to phonological sounds.
Mixing time for the asymmetric simple exclusion process in a random environment
Creators: name: Lacoin, Hubert
name: Yang, Shangjie
Publisher: name: arXiv
Year: 2021
Subjects: subject: Probability (math.PR)
subject: Mathematical Physics (math-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 60K37, 60J27

description: We consider the simple exclusion process in the integer segment $ [1, N]$ with $k\le N/2$ particles and spatially inhomogenous jumping rates. A particle at site $x\in [ 1, N]$ jumps to site $x-1$ (if $x\ge 2$) at rate $1-ω_x$ and to site $x+1$ (if $x \le N-1$) at rate $ω_x$ if the target site is not occupied. The sequence $ω=(ω_x)_{ x \in \mathbb{Z}}$ is chosen by IID sampling from a probability law whose support is bounded away from zero and one (in other words the random environment satisfies the uniform ellipticity condition). We further assume $\mathbb{E}[ \log ρ_1 ]<0$ where $ρ_1:= (1-ω_1)/ω_1$, which implies that our particles have a tendency to move to the right. We prove that the mixing time of the exclusion process in this setup grows like a power of $N$. More precisely, for the exclusion process with $N^{β+o(1)}$ particles where $β\in [0,1)$, we have in the large $N$ asymptotic $$ N^{\max\left(1,\frac {1}λ, β+ \frac 1 {2λ}\right)+o(1)} \le t_{\mathrm{Mix}}^{N,k} \le N^{C+o(1)}$$ where $λ>0$ is such that $\mathbb{E}[ρ_1^λ]=1$ ($λ=\infty$ if the equation has no positive root) and $C$ is a constant which depends on the distribution of $ω$. We conjecture that our lower bound is sharp up to sub-polynomial correction.
description: 35 pages, 5 figures
Effect of scalar leptoquarks on the lepton flavor violation decays of B meson
Creators: name: Sheng, Jin-Huan
name: Wang, Ru-Min
name: Yang, Ya-Dong
Publisher: name: arXiv
Year: 2018
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Leptoquarks have been suggested to solve a variety of discrepancies between the expected and observed phenomenon. In this paper, we investigate the effect of scalar leptoquarks on the lepton flavor violating B meson rare decays which involve the quark level transition $\bar{b} \to \bar{s} \ell^-_i \ell^+_j(i \neq j)$. The leptoquark parameter space is constrained by using the recently measured upper limits on the $\mathcal{B}(B_s^0 \to \ell^-_i \ell^+_j)$ and $\mathcal{B}(B \to K^{(*)}\ell^-_i \ell^+_j)$. Using such constrained leptoquark parameter space, some relevant physical quantities are also predicted and we find that the constrained New Physics parameters in the leptoquark model have very obvious effects on the relevant physical quantities in this paper. With future measurements of observable in $B \to K^{(*)}\ell^-_i \ell^+_j$ decays at the LHCb, more and more differentiated from the other NP explanations could be tested.
description: 16 pages;5 figures Appendix; publication in International Journal of Theoretical Physics