cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Investigations of the use of spent sorbent from the Ca looping process in cement manufacture and investigation of long-term CO2 uptake in cement and concrete
Creators: name: Hills, Thomas Peter
Publisher: name: Imperial College London
Year: 2016

description: This thesis comes in three distinct parts: an evaluation of concrete carbonation to improve accuracy of lifecycle carbon emissions of concrete; a detailed rationale outlining the importance of carbon capture and storage (CCS) for Portland cement and discussing viable technology deployment trajectories for the UK; and experimental investigation of one of the most promising carbon capture technology for the industry. Using a data set of around 2000 points from the literature, two regression models using common predictor variables were generated using multilevel modelling. One of these was used to quantify the amount of CO2 absorbed annually by all the world’s concrete. The best estimate for 2012 was 136 Mt CO2. To better understand the current development status of five carbon capture technologies in the cement industry, a sector-specific Technology Readiness Level (TRL) scale was produced. From this, dates of commercialisation are predicted and used in a bottom-up model which simulates the installation of carbon capture on UK cement plants at times when they are expected to be closed for other major alterations. The calculated rate of decarbonisation is compared with those presented in existing top-down pathways to determine how realistic the latter are. They seem realistic but only in a supportive policy environment. One of the five promising technologies studied was calcium looping. It is attractive for the Portland cement industry because the mainly CaO waste from the capture plant can be used as a raw material in the cement plant. The effect of looping on the compressive strength of cement was investigated. There was not statistically significant (α = 0.05) difference between the compressive strength of cement made with CaO looped 0, 5 and 10 times. Some significant differences were observed between cements which differed in other ways such as the type of sorbent used as the raw material.
Heavy oil upgrading through oxidative cracking in near-critical and supercritical water
Creators: name: Arcelus Arrillaga, Pedro Manuel
Publisher: name: Imperial College London
Year: 2016

description: The gradual decline in conventional oil production combined with an increasing world energy demand has made the production and upgrading of heavy and extra heavy oil feedstocks crucial for the future of the global energy market. Properties of heavy oil such as high viscosity and high specific gravity as well as the high percentage of asphaltenes, heteroatoms and metals cause severe problems during extraction and refining processes. As a result, traditional upgrading technologies are not suitable as a standalone method to process these feedstocks. This makes necessary the development of alternative or complementary technologies to process heavy oil feedstocks in a more efficient and environmentally friendly way. This work is aimed to study an alternative heavy oil upgrading process that takes advantage of the unique properties of water at near-critical and supercritical conditions as reaction medium to perform the oxidative cracking of heavy oil feedstocks. The process consists of three main stages including the partial oxidation, cracking of the molecule, and removal of part of the oxygen incorporated from the final product. The process was studied using phenanthrene and methyl naphthalene as heavy oil model compounds and also Maya oil vacuum residue as real feedstock. This was performed in a purposely built microbomb batch reactor and an oxidative cracking flow reactor. The effect of the main process variables and the potential reaction pathways were studied with model compounds. Then the process was tested with real feedstock and the inclusion of a zeolite based catalyst to enhance yields to light oil was considered. It was found that process conditions have an important influence in the yield and selectivity to different product fractions. Optimum conditions to maximize the production of organic soluble products were determined. It was observed that polycyclic aromatic hydrocarbons were not reactive in the absence or at low concentration of reactive oxygen species. However, oxygenated intermediates continued to react in water alone. In addition, it was observed that intermediate products were mainly oxygenated compounds and that the oxygenation proceeded preferentially through central rings. A hydrogen rich gas product was obtained. Experiments with vacuum residue showed that high yields to liquid products with low boiling point are obtained keeping low yields to coke at most conditions studied. The addition of a zeolite based catalyst showed improvement in the process, increasing the yield to light oil and reducing the average molecular weight of the product. Heteroatoms and metals present were mainly removed as coke and showed to be relatively stable.
Ovis aries subsp. hispanica Linnaeus, 1758, subspec. nov.
Creators: name: Linnaeus, Carolus
Publisher: name: Laurentius Salvius
Year: 1758
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Artiodactyla
Bovidae
Ovis
Ovis aries
Ovis aries subsp. hispanica

description: Ovis aries subsp. hispanica [subspec. nov.]
cornuta cornuum spira extrorsum tracta.
description: Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on page 70, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206
title: The Influence of C-Ions and X-rays on Human Umbilical Vein Endothelial Cells
Creators: name: Helm, Alexander
name: Lee, Ryonfa
name: Durante, Marco
name: Ritter, Sylvia
Publisher: name: Frontiers Media S.A.
Year: 2024

description: Damage to the endothelium of blood vessels, which may occur during radiotherapy, is discussed as a potential precursor to the development of cardiovascular disease. We thus chose human umbilical vein endothelial cells as a model system to examine the effect of low- and high-linear energy transfer (LET) radiation. Cells were exposed to 250 kV X-rays or carbon ions (C-ions) with the energies of either 9.8 MeV/u (LET = 170 keV/μm) or 91 MeV/u (LET = 28 keV/μm). Subculture of cells was performed regularly up to 46 days (~22 population doublings) post-irradiation. Immediately after exposure, cells were seeded for the colony forming assay. Additionally, at regular intervals, mitochondrial membrane potential (MMP) (JC-1 staining) and cellular senescence (senescence-associated β-galactosidase staining) were assessed. Cytogenetic damage was investigated by the micronucleus assay and the high-resolution multiplex fluorescence in situ hybridization (mFISH) technique. Analysis of radiation-induced damage shortly after exposure showed that C-ions are more effective than X-rays with respect to cell inactivation or the induction of cytogenetic damage (micronucleus assay) as observed in other cell systems. For 9.8 and 91 MeV/u C-ions, relative biological effectiveness values of 2.4 and 1.5 were obtained for cell inactivation. At the subsequent time points, the number of micronucleated cells decreased to the control level. Analysis of chromosomal damage by mFISH technique revealed aberrations frequently involving chromosome 13 irrespective of dose or radiation quality. Disruption of the MMP was seen only a few days after exposure to X-rays or C-ions. Cellular senescence was not altered by radiation at any time point investigated. Altogether, our data indicate that shortly after exposure C-ions were more effective in damaging endothelial cells than X-rays. However, late damage to endothelial cells was not found for the applied conditions and endpoints.
Cluster Mass Estimate and a Cusp of the Mass Density Distribution in Clusters of Galaxies
Creators: name: Makino, Nobuyoshi
name: Asano, Katsuaki
Publisher: name: arXiv
Year: 1998
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We study density cusps in the center of clusters of galaxies to reconcile X-ray mass estimates with gravitational lensing masses. For various mass density models with cusps we compute X-ray surface brightness distribution, and fit them to observations to measure the range of parameters in the density models. The Einstein radii estimated from these density models are compared with Einstein radii derived from the observed arcs for Abell 2163, Abell 2218, and RX J1347.5-1145. The X-ray masses and lensing masses corresponding to these Einstein radii are also compared. While steeper cusps give smaller ratios of lensing mass to X-ray mass, the X-ray surface brightnesses estimated from flatter cusps are better fits to the observations. For Abell 2163 and Abell 2218, although the isothermal sphere with a finite core cannot produce giant arc images, a density model with a central cusp can produce a finite Einstein radius, which is smaller than the observed radii. We find that a total mass density profile which declines as $\sim r^{-1.4}$ produces the largest radius in models which are consistent with the X-ray surface brightness profile. As the result, the extremely large ratio of the lensing mass to the X-ray mass is improved from 2.2 to 1.4 for Abell 2163, and from 3 to 2.4 for Abell 2218. For RX J1347.5-1145, which is a cooling flow cluster, we cannot reduce the mass discrepancy.
description: 23 pages, 10 figures, Latex, uses aasms4.sty, accepted for publication in ApJ, Part 1
Greenhouse gas emissions induced by Mexican intermediate trade
Creators: name: Orozco-Morales, Roberto Carlos
Publisher: name: Zenodo
Year: 2024

description: The increase in trade in Mexico (imports and exports) has also generated an increase in greenhouse gas emissions. However, differentiated patterns are observed. While secondary activities are characterized by being net importers of emissions, primary and service activities are net exporters of emissions.

 

Imports from the Mexican's main export activities - electronic and electrical equipment and vehicles - generate the highest emissions quotas abroad. In other words, the requirements for imported intermediate inputs are developed in polluting production processes in their places of origin.

 

Since the macroeconomic perspective, the results suggest analyzing the supply chains of the mentioned sectors in terms of their energy efficiency.
The Morphological Evolution of Galaxies
Creators: name: Ellis, R. S.
Publisher: name: arXiv
Year: 1995
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: I review the general progress made in the study of galaxy evolution concentrating on the impact of systematic ground-based spectroscopic surveys of faint galaxies and high resolution imaging with Hubble Space Telescope. The picture emerging is one where massive regular galaxies have changed little since redshift $z\simeq$1, whereas there has been a marked decline in the abundance of less massive star forming dwarf galaxies. Reconciling these trends with the conventional hierarchical growth of structure on galactic scales and determining the fate of the star forming dwarfs remains a major unsolved problem in contemporary cosmology
description: gzipped postscript. The preprint is also available at http://www.ast.cam.ac.uk/preprint/PrePrint.html
TERMINOLOGIYADA GIPERO-GIPONIMIK HODISALAR
Creators: name: Ermatov, Ixtiyor
name: Axrorov, Alisher
name: Mamaraximov, Sirojiddin
Publisher: name: Zenodo
Year: 2024

description: Maqolada terminologiya tizimida zid ma’noli bo‘lmagan leksik birliklar va ularning lug‘aviy-mazmuniy medioqurilmalari, ularning denotativ asosi har xil bo‘lgan lug‘aviy birliklar (giponim, giperonim, ekvonim, partonim, funktsionimlar)dan biri bo‘lgan giponim terminlar munosabati haqida fikr yuritiladi. Tilshunoslik terminlari maqolaning illyustrativ materiali sifatida xizmat qiladi.
Conservation payments in data-poor, developing-world fisheries
Creators: name: Bladon, Annabelle Jade
Publisher: name: Imperial College London
Year: 2016

description: Effective fisheries management is limited in the developing world by weak institutions, inadequate financing and a lack of reliable data. Conservation payments are a novel concept in fisheries management. In this thesis I take a multidisciplinary approach to explore whether they could help to address gaps in traditional fisheries management, using the Bangladesh hilsa (Tenualosa ilisha) fishery and its ongoing payment scheme as a case study. I develop a qualitative frame of reference against which current or potential hilsa management interventions could be evaluated, demonstrating that – even in data-limited fisheries – counterfactuals can be developed and used to guide management. In the absence of data for formal evaluation, I then investigate the scope for additionality in hilsa management by assessing the evidence for and against a reconstructed theory of change. Although the potential for overall additionality is equivocal, my findings demonstrate scope for individual elements of the management package to have had additionality, and provide some support for the use of conservation payments. As is common in artisanal fisheries management, hilsa management is focused on the protection of juveniles. Through population modelling, I demonstrate that size selectivity is much less important than catch volume, in terms of effect on overall hilsa population biomass. This analysis suggests that the targeting of payments would benefit from a more rigorous ecological foundation. Through statistical modelling of household survey data, I find a strong spatial pattern in payment distribution that reflects the political economy of Bangladesh rather than the official social goals of the scheme. I also find evidence of strong trade-offs between social and ecological goals. Finally, I investigate the potential for Conservation Trust Funds (CTFs) to enhance the sustainability of payments. Developing-world fisheries pose challenges to the translation of conservation payments from concept to reality. I find that CTFs can support and catalyse the development of enabling conditions for sustainable payment institutions, but only if best practice standards are followed.
Additional file 1: of Transcriptome dynamics of rooting zone and aboveground parts of cuttings during adventitious root formation in Cryptomeria japonica D. Don
Creators: name: Fukuda, Yuki
name: Hirao, Tomonori
name: Mishima, Kentaro
name: Ohira, Mineko
name: Hiraoka, Yuichiro
name: Takahashi, Makoto
name: Watanabe, Atsushi
Publisher: name: figshare
Year: 2018
Subjects: subject: Genetics
subject: FOS: Biological sciences
subject: Molecular Biology
subject: Ecology
subject: 69999 Biological Sciences not elsewhere classified
subject: Developmental Biology
subject: Plant Biology

description: Figure S1. Validation of microarray data by qRT-PCR at the base. Bars represent the means Âą standard errors of the means (SE) for three biological replicates. (DOCX 142 kb)
Cosmochemistry of iron meteorites; trace element composition of metal and sulfide phases
Creators: name: Leclerc, Marlene
Publisher: name: Imperial College London
Year: 2015

description: Trace elements composition of the metal and sulfide phases in iron meteorites have been studied in 42 iron meteorites and 2 pallasites. 19 iron meteorites thick sections containing sulfide inclusions have been mapped and their mineralogy, tex- ture and major and minor element compositions analyzed by SEM and EPMA and their trace elements composition measured using LA-ICP-MS. A highly homoge- neous fragment of Cape York troilite has been found suitable to be used as a sulfide standard for moderately volatile elements in LA-ICP-MS analysis. A further 34 sulfide samples were digested in ultrapure acids and analyzed by Solution-ICP-MS. In thick sections, the iron meteorites Dronino, Nantan and Patos de Minas showed a rim of Ni and Co-rich sulfides around troilite (FeS) nodules, they are terrestrial weathering products of the troilite. X-RD analysis produced the char- acteristic pattern for pentlandite ((Fe,Ni)9S8) and heazlewoodite (Ni3S2). Analy- sis of powder from a sulfide nodule of Uruac ̧u also showed presence of magnetite (Fe3O4) and goethite (FeO(OH)), infilling cracks within the troilite nodule. Terres- trial weathering and shock-melting are found not to affect the moderately volatile trace elements content of the sulfide, except for Ni and Co that are enriched by terrestrial weathering. Bulk iron meteorite compositions have been calculated from LA-ICP-MS and Solution-ICP-MS measurements. They show a depletion of moderately volatile ele- ments (condensing between 1350 and 650 degrees K) and the strongly volatiles Cd and In. The depletion is greater for IVA irons. IABs, IIABs, IIIABs and pallasites have similar levels of depletion which are greater than what has been observed for ordinary chondrites. The selenium content of the sulfide is inversely correlated with bulk Ni content and the bulk selenium vs. bulk sulfur content show loss of a sulfide liquid from the IIIAB and IVA parent-body but not from the IAB group which lies on the CI line.
Mesh adaptation strategies for compressible flows using a high-order spectral/hp element discretisation
Creators: name: Ekelschot, Dirk
Publisher: name: Imperial College London
Year: 2016

description: An accurate calculation of aerodynamic force coe cients for a given geometry is of fundamental importance for aircraft design. High-order spectral/hp element methods, which use a discontinuous Galerkin discretisation of the compressible Navier-Stokes equations, are now increasingly being used to improve the accuracy of flow simulations and thus the force coe cients. To reduce error in the calculated force coe cients whilst keeping computational cost minimal, I propose a p-adaptation method where the degree of the approximating polynomial is locally increased in the regions of the flow where low resolution is identified using a goal-based error estimator. We initially calculate a steady-state solution to the governing equations using a low polynomial order and use a goal-based error indicator to identify parts of the computational domain that require improved solution accuracy and increase the approximation order there. We demonstrate the cost-effectiveness of our method across a range of polynomial orders by considering a number of examples in two- and three-dimensions and in subsonic and transonic flow regimes. Reductions in both the number of degrees of freedom required to resolve the force coe cients to a given error, as well as the computational cost, are both observed in using the p-adaptive technique. In addition to the adjoint-based p-adaptation strategy, I propose a mesh deformation strategy that relies on a thermo-elastic formulation. The thermal-elastic formulation is initially used to control mesh validity. Two mesh quality indicators are proposed and used to illustrate that by heating up (expanding) or cooling down (contracting) the appropriate elements, an improved robustness of the classical mesh deformation strategy is obtained. The idea is extended to perform shock wave r-adaptation (adaptation through redistribution) for high Mach number flows. The mesh deformation strategy keeps the mesh topology unchanged, contracts the elements that cover the shock wave, keeps the number of elements constant and the computation as e cient as the unrefined case. The suitability of r-adaptation for shock waves is illustrated using internal and external compressible flow problems.
Nonlinear stability of prestressed stayed columns with multiple crossarm systems
Creators: name: Yu, Jialiang
Publisher: name: Imperial College London
Year: 2016

description: Prestressed stayed steel columns are increasing in popularity in the construction industry. This type of structure possesses a considerably higher buckling resistance as compared to the conventional column without a commensurate increase in self-weight, owing to the extra stiffnesses provided by the system of crossarms and cable stays. Most of the previous literature focused on the buckling load of the stayed column while systematic studies on the post-buckling behaviour of the single-bay column have only been conducted more recently. Although the significance of the post-buckling behaviour of such structures has already been demonstrated, certain relevant topics have not been satisfactorily studied for the stayed columns with multiple crossarm systems, which potentially possess even higher buckling resistances as compared to the single crossarm cases. Therefore, the aim of the current thesis is to reveal the post-buckling behaviour of the prestressed stayed column with multiple crossarms along the length. A finite element model of a prestressed stayed column with multiple crossarms along the length is developed with the initial imperfections and the prestress taken into consideration. Interactive buckling is found to be the most dangerous case particularly when the critical buckling mode is anti-symmetric. It is found that the post-buckling behaviour is strongly linked to the actual geometric arrangement of the structure. Sensitivities to the levels of the prestress and the initial imperfections are also presented. The observations obtained from the FE model are first validated qualitatively by a simplified analytical model. The simplified model also reveals the process for how the pure buckling modes interact during the post-buckling stage. To compare with the results of the FE model quantitatively, a more sophisticated analytical model is subsequently developed. The total potential energy of the system is formulated in conjunction with the Rayleigh--Ritz method. The slackening of the stays is also successfully simulated. An identical observation, in that interactive buckling governs the post-buckling response when anti-symmetric buckling is critical, is obtained also. Excellent quantitative agreement is found between the results from the FE and the more sophisticated analytical model. Parametric studies on the geometric configurations where interactive buckling is most significant are also presented. Finally, a large number of separate cases with different structural geometries and levels of prestress are studied. The actual optimal prestress, which accounts for the load carrying capacity of the column and the required material resistances of different structural components, is determined for the triple-bay stayed column. This demonstrates that the nonlinear response of the stayed column system is practically important from a safety as well as an efficiency perspective.
Food Price Transmission and Economic Development
Creators: name: Elleby, Christian
name: Jensen, Frank
Publisher: name: Taylor & Francis
Year: 2018
Subjects: subject: Medicine
subject: Neuroscience
subject: Biotechnology
subject: 59999 Environmental Sciences not elsewhere classified
subject: FOS: Earth and related environmental sciences
subject: Ecology
subject: FOS: Biological sciences
subject: Sociology
subject: FOS: Sociology
subject: Cancer
subject: Science Policy

description: In this paper we challenge the conventional wisdom that the world’s poorest countries are also the most vulnerable to spikes in international food prices. We derive an inverted U-shaped relationship between food price transmission and the development level of a country from a theoretical model. This prediction is subsequently tested in two sets of regressions where economic development is approximated by per capita income and where we control for a number of other potential determinants of food price transmission. The first set of regressions is based on estimated transmission elasticities and the second on actual domestic food price changes during spikes in international food prices. In both sets of regressions we find strong evidence of the existence of an inverted U-shaped relation between food price transmission and income. Thus, food prices in middle income (rather than in low income) countries respond the strongest to changes in international food prices, implying that the poor in these countries are the most exposed to spikes in food prices. We also show that the factors explaining the variation in the estimated transmission elasticities can explain the variation in domestic food price changes during spikes in international food prices equally well.
Augmenting pulmonary rehabilitation in chronic obstructive pulmonary disease: studies of ACE-inhibition and nitrate supplementation
Creators: name: Curtis, Katrina Jane
Publisher: name: Imperial College London
Year: 2016

description: This thesis addresses two approaches to enhancing exercise capacity in chronic obstructive pulmonary disease (COPD). The first is by manipulation of the renin-angiotensin system through angiotensin-converting enzyme (ACE) inhibition to establish if this can augment the response to pulmonary rehabilitation. The second is nitrate supplementation, assessed for its effects on endurance exercise parameters. In a cross-sectional study of 78 patients with at least moderate severity COPD I found no association between ACE genotype and exercise parameters during incremental cycle ergometry, in contrast to previous work from a Chinese group. The role of the renin-angiotensin pathway in skeletal muscle impairment in COPD is likely to be highly complex, and there are both potential beneficial and adverse effects of angiotensin II, and potentially conflicting effects on strength and endurance exercise capacity. The absence of differences in a cross-sectional study do not preclude the possibility that the ACE genotype may influence the response to both training and detraining through physical inactivity, and this remains an area of possible future research. I went on to test the effect of the ACE-inhibitor enalapril on the response to pulmonary rehabilitation, focussing on the change in peak exercise capacity. I undertook a double-blind randomised controlled trial of 80 COPD patients with at least moderate airflow obstruction referred for pulmonary rehabilitation. There was evidence of adequate suppression of ACE activity through both the suppression of serum ACE levels and alteration in blood pressure parameters in the enalapril treated arm. Contrary to expectations the peak power achieved on incremental cycle ergometry increased more in the placebo arm of the study than the ACE-inhibitor treated arm. No significant differences were noted in computed tomography measures of muscle bulk, quadriceps strength or health-related quality of life. Thus, in subjects without a pre-existing clinical indication for ACE-inhibition, use of the ACE-inhibitor enalapril reduced the response to exercise training in COPD. I also conducted a pilot study to investigate the role of acute nitrate supplementation on endurance exercise characteristics and oxygen consumption during endurance exercise in COPD. I recruited 25 subjects into a double-blind, placebo-controlled, single-dose cross-over study. Nitrate supplementation, in the form of beetroot juice at a dose of 12.9 mmoles, significantly lowered resting diastolic blood pressure and isotime pulmonary oxygen consumption. This did not translate into an improvement in endurance time. This preliminary work will provide the basis for further studies, including the potential role of nitrate supplementation in enhancing the response to pulmonary rehabilitation and the role of nitrate supplementation on exercise capacity in individuals with exercise induced hypoxaemia.
Entanglement spectroscopy with a depth-two quantum circuit
Creators: name: Subasi, Yigit
name: Cincio, Lukasz
name: Coles, Patrick J.
Publisher: name: arXiv
Year: 2018
Subjects: subject: Quantum Physics (quant-ph)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Noisy intermediate-scale quantum (NISQ) computers have gate errors and decoherence, limiting the depth of circuits that can be implemented on them. A strategy for NISQ algorithms is to reduce the circuit depth at the expense of increasing the qubit count. Here, we exploit this trade-off for an application called entanglement spectroscopy, where one computes the entanglement of a state $| ψ\rangle$ on systems $AB$ by evaluating the Rényi entropy of the reduced state $ρ_A = {\rm Tr}_B(| ψ\rangle \langle ψ|)$. For a $k$-qubit state $ρ(k)$, the Rényi entropy of order $n$ is computed via ${\rm Tr}(ρ(k)^{n})$, with the complexity growing exponentially in $k$ for classical computers. Johri, Steiger, and Troyer [PRB 96, 195136 (2017)] introduced a quantum algorithm that requires $n$ copies of $| ψ\rangle$ and whose depth scales linearly in $k*n$. Here, we present a quantum algorithm requiring twice the qubit resources ($2n$ copies of $| ψ\rangle$) but with a depth that is independent of both $k$ and $n$. Surprisingly this depth is only two gates. Our numerical simulations show that this short depth leads to an increased robustness to noise.
description: 10 pages, 6 figures
Repeated Relativistic Ejections in GRS 1915+105
Creators: name: Rodriguez, L. F.
name: Mirabel, I. F.
Publisher: name: arXiv
Year: 1998
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: In 1994 February-August we observed with the VLA four ejection events of radio emitting clouds from the high energy source GRS 1915+105. These events are all consistent with anti-parallel ejections of twin pairs of clouds moving away from the compact source at $\sim$ 0.92 of the speed of light and angles of $\sim$ 70$^{\circ}$ with respect to the line of sight. The flux ratios and time evolution of the expelled clouds are consistent with actual motions of the radiating matter rather than with the simple propagation of pulses in a medium moving at slower velocities. The large kinetic power of the sudden, short, and rather discontinuous ejections exceeds by more than an order of magnitude the maximum steady photon luminosity of the source, suggesting that in GRS 1915+105 a radiation acceleration mechanism of the ejecta is unlikely. As in other galactic and extragalactic radio sources, the decrease in flux density as a function of angular separation from the central source shows a steepening with distance. Additional ejection events have been observed in 1995 and 1997 and we compare them with the 1994 events.
description: 20 pages, 7 figures. To appear in The Astrophysical Journal, January 10, 1999 issue
Improving high performance computing using code generation and compilation techniques
Creators: name: Bercea, Gheorghe-Teodor
Publisher: name: Imperial College London
Year: 2017

description: In an ideal world, scientific applications would be expressed as high-level compositions of abstractions that encapsulate parallelism and deliver near-optimal performance with low maintainability costs. The alternative, where such abstractions are unavailable, is for application programmers to control execution using an appropriate explicitly parallel programming model. In this thesis we explore both approaches, represented by the Firedrake framework and the OpenMP programming model respectively. We also explore how OpenMP can support high level abstractions such as Firedrake. Firedrake is designed as a composition of domain-specific abstractions for solving partial differential equations via the finite element method. We extend Firedrake with support for extruded meshes frequently used in geophysical simulations. We introduce algorithms for numbering and iterating over any discretization supported by an extruded mesh. Starting with version 4.0, OpenMP computations, previously intended exclusively for the CPU, can be offloaded to accelerators and coprocessors. We introduce code generation schemes for offloading single and nested OpenMP parallel constructs in the CLANG/LLVM toolchain. The schemes map OpenMP directives to the hardware model of the accelerator enabling the programmer to use OpenMP in a prescriptive way. Performance is evaluated on the extruded mesh extensions to Firedrake as well as on LULESH, a widely ported proxy application intended to be representative of an important portion of Department of Energy’s scientific codes. In the case of Firedrake, performance is shown to reach significant percentages of theoretical hardware limits. For OpenMP, the runtime is compared against hand-optimized implementations employing the accelerator-specific CUDA C/C++ language extensions. The additions to the Firedrake framework combine both approaches into a single toolchain containing a newly introduced OpenMP 4.0 Firedrake backend with functionality equivalent to all existing Firedrake backends. OpenMP 4.0 is used as a single representation for both CPU and GPU platforms thus simplifying the application of target-specific optimisations. The OpenMP 4.0 backend improves maintainability through code reuse and will deliver gains in portability as offloading support in CLANG advances.
Weak Interactions in Supernova Cores and Saturation of Nucleon Spin Fluctuations
Creators: name: Sigl, Guenter
Publisher: name: arXiv
Year: 1995
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Extrapolation of perturbative nucleon spin fluctuation rates seems to suggest a strong suppression of weak interactions in supernova cores. We derive a new sum rule for the dynamical spin-density structure function which relates the spin fluctuation rate to the average nuclear interaction energy. For a bremsstrahlung like structure function profile we show that instead of strongly decreasing, the neutrino scattering cross section is roughly density independent and axion emission rates increase somewhat slower than the lowest order emissivities towards the center of a hot supernova core.
description: 9 latex pages, 1 uuencoded postscript figure added via figures command
title: Effects of a Syllable-Based Reading Intervention in Poor-Reading Fourth Graders
Creators: name: Müller, Bettina
name: Richter, Tobias
name: Karageorgos, Panagiotis
name: Krawietz, Sabine
name: Ennemoser, Marco
Publisher: name: Frontiers Media S.A.
Year: 2024

description: In transparent orthographies, persistent reading fluency difficulties are a major cause of poor reading skills in primary school. The purpose of the present study was to investigate effects of a syllable-based reading intervention on word reading fluency and reading comprehension among German-speaking poor readers in Grade 4. The 16-session intervention was based on analyzing the syllabic structure of words to strengthen the mental representations of syllables and words that consist of these syllables. The training materials were designed using the 500 most frequent syllables typically read by fourth graders. The 75 poor readers were randomly allocated to the treatment or the control group. Results indicate a significant and strong effect on the fluency of recognizing single words, whereas text-level reading comprehension was not significantly improved by the training. The specific treatment effect provides evidence that a short syllable-based approach works even in older poor readers at the end of primary school.
WASH and Nutrition Synergies: The Case of Tunisia
Creators: name: Cuesta, Jose
name: Maratou-Kolias, Laura
Publisher: name: Taylor & Francis
Year: 2018
Subjects: subject: Space Science
subject: Medicine
subject: Biotechnology
subject: 59999 Environmental Sciences not elsewhere classified
subject: FOS: Earth and related environmental sciences
subject: Sociology
subject: FOS: Sociology
subject: 69999 Biological Sciences not elsewhere classified
subject: FOS: Biological sciences
subject: 19999 Mathematical Sciences not elsewhere classified
subject: FOS: Mathematics
subject: Cancer
subject: Science Policy
subject: 110309 Infectious Diseases
subject: FOS: Health sciences
subject: Computational Biology

description: This paper develops a simple econometric strategy to operationalise the United Nations Children’s Fund’s (UNICEF’s) conceptual framework for nutrition. It estimates the extent to which child stunting correlates with investments in water, sanitation, and hygiene (WASH) across population groups (poor and nonpoor) and residence (urban and rural). Moving away from estimating single intervention marginal returns, the empirical framework of intervention packages is tested in Tunisia, a country with notable but uneven progress in reducing stunting. A successful nutritional strategy will thereby require mapping the distinctive intervention packages by residence and socio-economic status, away from universal policies, that more strongly correlate with reduction in stunting.
Developing and evaluating a global model for landscape fires
Creators: name: Mangeon, Stephane
Publisher: name: Imperial College London
Year: 2017

description: Fires are integral to the global environment. Changes to that environment have, and will, modify fire behaviour. In turn, fires impact the land surface by burning vegetation, and the atmosphere by emitting large amounts of heat, gases and aerosols. I first studied extreme wildfires in North America, finding satellite observations estimate 79% of the burnt area logged by ground crews during firefighting campaigns, and only 54% during peak burning days. I then describe the development of one such model: the INteractive Fire and Emission algoRithm for Natural envirOnments (INFERNO), a global fire model developed for the UK Met Office’s Unified Model. It innovates by providing a simple parameterisation which uses information on temperature, humidity, soil moisture, and vegetation, to estimate burnt area and fire emissions at the global scale. Live vegetation is used as a proxy for fuel, in reality, litter and ground fuel are predominant. The model performs well against fire danger indices and observations, but shows regional biases and a notable underestimate of emissions during El-Niño years. INFERNO was most sensitive to changes in soil moisture, with regional patterns of fire also strongly influenced by number of ignitions, fuel density, temperature and humidity. Results from multiple fire models participating in the Fire Model Intercomparison Project (FireMIP) show similar performances, with a multi-model mean underestimate of global burnt area, and overestimate of emissions. I identified systematic biases in fuel consumption, which models generally underestimate in tropical forests and peatlands compared to field observations. Models particularly disagreed in areas with strong human-influences. Global fire models are central to our understanding of how fires interact with the land and the atmosphere on large scales, and hold the potential to be an integral part of global models in the future and to catalyse new understandings of feedbacks in the Earth system.
Quantum coins and quantum sampling
Creators: name: Dale, Howard
Publisher: name: Imperial College London
Year: 2016

description: Quantum computing is rapidly becoming one of the largest research areas in quantum physics and yet we are still unable to prove the superiority of quantum computing over classical with the exception of a few contrived and unrealistic scenarios. Understanding the areas in which quantum computing provides an advantage and, more importantly, where that advantage comes from is the key to making progress in the field. We certainly do not solve this mystery in this thesis but do explore some unconventional routes through which answers may be found in the future. To this end we explore quantum advantage in a different computational setting. Rather than working with Turing Machines as most research does, we focus on the Bernoulli Factory: a randomness processing scheme studied in the fields of statistics and computer science. The Bernoulli Factory takes an infinite string of random bits generated with a fixed unknown bias as input and outputs a single random bit, the bias of which is a function of the input bias. This can be seen more intuitively as generating one biased coin from another, given a desired relationship between the two biases. The Bernoulli Factory is inherently probabilistic, like quantum mechanics, and so, it leads us to questions about the fundamental nature of quantum randomness and quantum sampling. We find, as we hoped, that the Bernoulli Factory is more tractable than the Turing Machine and that we are able to prove quantum superiority in both resource efficiency and classes of computable functions. We first give the quantum analogue of the classical Keane-O'’Brien theorem which establishes the increased class of computable functions for the quantum case. We then adjust the problem in a variety of ways, such as introducing multiple coins, errors in state preparation, phases and restriction on the bias or operations allowed. These lead to additional results which lend insight into the problems faced in quantum computing as well as the nature of quantum randomness.
title: Διερευνώντας τον παραμετρικοποιημένο χώρο λύσεων ενός επιλύσιμου μοντέλου πυρηνικού πολέμου
title: Exploring the parametrized solution space of a solvable nuclear war model
titleType: AlternativeTitle
Creators: name: Ανδρής, Ιωάννης
Publisher: name: Πανεπιστήμιο Πειραιώς
Year: 2021
Subjects: subject: Nuclear war
subject: Simulation
subject: Game theory
subject: Strategic stability
subject: Deterrence

description: Στόχος της εργασίας είναι η συστηματική διερεύνηση του χώρου λύσεων ενός επιλύσιμου μοντέλου πυρηνικού πολέμου, όπως αυτό προτάθηκε από τον Norman C. Dalkey, για τις διάφορες τιμές των παραμέτρων του, οι οποίες παράγουν διαφορετικά προφίλ αντιπάλων. Στην πορεία, επιχειρούμε να αναγνωρίσουμε τις βέλτιστες στρατηγικές όπως αυτές προκύπτουν από το χώρο λύσεων, να εξετάσουμε την βασική παραδοχή του μοντέλου ότι μια μεικτή στρατηγική στόχευσης counterforce/countervalue είναι εφικτή, ενώ προτείνουμε και μια μικρή τροποποίηση του μοντέλου, η οποία αντανακλά καλύτερα το αναδυόμενο γεωπολιτικό περιβάλλον που διακρίνεται από την ύπαρξη πολλών παικτών.
Cosmological Models of Gamma-Ray Bursts
Creators: name: Dermer, Charles D.
name: Weiler, Thomas J.
Publisher: name: arXiv
Year: 1995
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We review models of cosmological gamma-ray bursts (GRBs). The statistical and $γ$-ray transparency issues are summarized. Neutron-star and black-hole merger scenarios are described and estimates of merger rates are summarized. We review the simple fireball models for GRBs and the recent work on non-simple fireballs. Alternative cosmological models, including models where GRBs are analogs of active galactic nuclei and where they are produced by high-field, short period pulsars, are also mentioned. The value of neutrino astronomy to solve the GRB puzzle is briefly reviewed.
description: 12 pages, no figures, uuencoded compressed postscript file. Invited review to appear in the proceedings of the 29th ESLAB Symposium "Towards the Source of Gamma-Ray Bursts," Noordwijk, Netherlands, 25-27 April, 1995
Essays on risk and profitability in the future British electricity industry
Creators: name: Avagyan, Vitali
Publisher: name: Imperial College London
Year: 2016

description: This thesis analyses risk and profitability issues in the future British electricity industry through three different studies. The first study develops a novel and fully endogenous portfolio investment model for firms in a competitive electricity industry when they face uncertainties from fuel prices, demand levels, carbon price and renewable penetration. This study finds that both risk aversion and carbon price are crucial factors for investments in nuclear technology. The second study analyses the impact of the cost of capital on optimal investments. Two distinct costs of capital of a project are considered: one in the pre-development and construction (pre-operation) phase and the other in the operation phase. The pre-operation cost of capital is based on the complex and capital-intensive nature of a project, which prevents potential investors from undertaking them under high costs – this is the first driving force for investment followed by the operation cost of capital. Operation cost of capital is based on a company’s ability to generate cash flows that cover debt requirements by varying the debt-equity ratio that a firm can attain. The greater the cash-flow risk, the lower is the level of debt that the firm can include in its financing, and hence, the higher the weighted average cost of capital, given that debt generally benefits from tax shield. The third study analyses the profit risk of energy storage when it faces fuel-price risk. Specifically, it assesses the future electricity industry with different levels of renewable penetration and storage energy capacity. The study shows that energy storage profits depend on the electricity price risk when it makes profits from arbitrage and reserve provision and also shows that storage profit has a positive correlation with that of other generators, especially with profits of gas stations, and this correlation is moderated with the level of electricity demand.
Ovis aries subsp. polycerat Linnaeus, 1758, subspec. nov.
Creators: name: Linnaeus, Carolus
Publisher: name: Laurentius Salvius
Year: 1758
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Artiodactyla
Bovidae
Ovis
Ovis aries
Ovis aries subsp. polycerat

description: Ovis aries subsp. polycerat [subspec. nov.]
Polycerata e gotlandia 248. Aldr. bisulc. 397.
description: Published as part of Linnaeus, Carolus, 1758, Systema Naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Stockholm :Laurentius Salvius on page 70, DOI: 10.5962/bhl.title.542, http://zenodo.org/record/3922206
Smart Contracts for Machine-to-Machine Communication: Possibilities and Limitations
Creators: name: Hanada, Yuichi
name: Hsiao, Luke
name: Levis, Philip
Publisher: name: arXiv
Year: 2018
Subjects: subject: Computers and Society (cs.CY)
subject: FOS: Computer and information sciences

description: Blockchain technologies, such as smart contracts, present a unique interface for machine-to-machine communication that provides a secure, append-only record that can be shared without trust and without a central administrator. We study the possibilities and limitations of using smart contracts for machine-to-machine communication by designing, implementing, and evaluating AGasP, an application for automated gasoline purchases. We find that using smart contracts allows us to directly address the challenges of transparency, longevity, and trust in IoT applications. However, real-world applications using smart contracts must address their important trade-offs, such as performance, privacy, and the challenge of ensuring they are written correctly.
Ανάπτυξη ασφαλούς λογισμικού - Έλεγχος ασφάλειας κώδικα (Java frameworks oriented)
Creators: name: Μαλαχιάς, Θεόδωρος
Publisher: name: Πανεπιστήμιο Πειραιώς
Year: 2021
Subjects: subject: Secure coding
subject: Java
subject: JSF
subject: Spring
subject: Struts
subject: Good practices

description: Η παρούσα διπλωματική έχει ως στόχο την παροχή οδηγιών σε μία ομάδα που αναπτύσσει λογισμικό για μία εφαρμογή web σε γλώσσα Java. Στο πρώτο κεφάλαιο αναλύονται οι διαφορετικές αρχιτεκτονικές που υπάρχουν για την ασφαλή ανάπτυξη εφαρμογών web. Επίσης παρέχονται συμβουλές για την ενίσχυση αυτού του στόχου. Στο κύριο μέρος της διπλωματικής και επόμενο κεφάλαιο αναλύονται διεξοδικά και με παραδείγματα καλές πρακτικές ασφαλούς προγραμματισμού σε Java. Σε κάθε κατηγορία πρακτικών αναλύεται ξεχωριστά πώς εφαρμόζεται σε διάφορα frameworks, η κάθε πρακτική, όπως το JSF, το Spring και το Struts με περισσότερη έμφαση στο JSF καθώς υπάρχει ευρύτερη χρήση του, αλλά και βιβλιογραφία. Στο τελευταίο κεφάλαιο αναλύεται το Static και Dynamic Security Testing (SAST & DAST) καθώς και λογισμικά ανοιχτού κώδικα που μπορεί κάποιος να χρησιμοποιήσει για να να διεξάγει SAST και DAST.