122,160 research outputs found
Author Co-Citation Analysis (ACA): a powerful tool for representing implicit knowledge of scholar knowledge workers
No full textIn the last decade, knowledge has emerged as one of the most important and valuable organizational assets. Gradually this importance caused to emergence of new discipline entitled ―knowledge management‖. However one of the major challenges of knowledge management is conversion implicit or tacit knowledge to explicit knowledge. Thus Making knowledge visible so that it can be better accessed, discussed, valued or generally managed is a long-standing objective in knowledge management. Accordingly in this paper author co- citation analysis (ACA) will be proposed as an efficient technique of knowledge visualization in academia (Scholar knowledge workers)
Unified mathematical treatment of complex cascaded bipartite networks: The case of collections of journal papers
No full textIn this study, a mathematical treatment is proposed for analysis of entities and relations among entities in
complex networks consisting of cascaded bipartite networks. This treatment is applied to the case of
collections of journal papers. In this case, entities are distinguishable objects and concepts, such as papers,
references, paper authors, reference authors, paper journals, reference journals, institutions, terms, and term
definitions. Relations are associations between entity-types such as papers and the references they cite, or
paper authors and the papers they write. An entity-relationship model is introduced that explicitly shows
direct links between entity-types and possible useful indirect relations. From this a matrix formulation and
generalized matrix arithmetic are introduced that allow easy expression of relations between entities and
calculation of weights of indirect links and co-occurrence links. Occurrence matrices, equivalence
matrices, membership matrices and co-occurrence matrices are described. A dynamic model of growth
describes recursive relations in occurrence and co-occurrence matrices as papers are added to the paper
collection. Graph theoretic matrices are introduced to allow information flow studies of networks of papers
linked by their citations. Similarity calculations and similarity fusion are explained. Derivation of feature
vectors for pattern recognition techniques is presented. The relation of the proposed mathematical
treatment to seriation, clustering, multidimensional scaling, and visualization techniques is discussed. It is
shown that most existing bibliometric analysis techniques for dealing with collections of journal papers are
easily expressed in terms of the proposed mathematical treatment: co-citation analysis, bibliographic
coupling analysis, author co-citation analysis, journal co-citation analysis, Braam-Moed-vanRaan (BMV)
co-citation/co-word analysis, latent semantic analysis, hubs and authorities, and multidimensional scaling.
This report discusses an extensive software toolkit that was developed for this research for analyzing and
visualizing entities and links in a collection of journal papers. Additionally, an extensive case study is
presented, analyzing and visualizing 60 years of anthrax research through a collection of journal papers.
When dealing with complex networks that consist of cascaded bipartite networks, the treatment presented
here provides a general mathematical framework for all aspects of analysis of static network structure and
network dynamic growth. As such, it provides a basic paradigm for thinking about and modeling such
networks: computing direct and indirect links, expressing and analyzing statistical distributions of network
characteristics, describing network growth, deriving feature vectors, clustering, and visualizing network
structure and growth
A Multi-Language Comparison of Influences on Author Verification using Character N-Grams
No full textWe create a new multi-language corpus for author verification based on Wikipedia talkpages, and evaluate the influence that differences in topic and time have on character n-gram author profiles. Topic alignment between two texts is found to increase author verification precision, and an authors writing style is found to change over time, but not more significantly after 3 years than after 1 year.Information ArchitectureWISElectrical Engineering, Mathematics and Computer Scienc
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
The atmospheric chemistry of Earth-like exoplanets: a 3D perspective
No full textExoplanets or planets around other stars than the Sun are ubiquitous in the galaxy, with great diversity in stellar and planetary environments. The hundreds of known terrestrial exoplanets with mass and radius similar to Earth are preferentially found around M-dwarf stars. The James Webb Space Telescope (JWST) is providing the first glimpses into the atmospheres of these terrestrial exoplanets which is most easily achieved for planets on close-in orbits around a small and cool host star. The close-in orbits induce strong star-planet gravitational interactions that synchronize the planet's orbital and rotational velocity in a process called tidal locking, producing spin-orbit resonances akin to the Moon's 1:1 and Mercury's 3:2 spin-orbit resonance. Understanding the effects of spin-orbit resonances on atmospheric physics and chemistry is crucial to determine habitability, interpret spectroscopic observations, and put potential biosignatures (signs of biological processes in an atmosphere) into the environmental context.
Comprehensive 3D General Circulation Models (GCMs) that describe the physical processes in a planetary atmosphere have been employed to explore the habitability and observability of such exoplanets. The simulations show that heat transport from a permanent dayside to a permanent nightside prevents atmospheric collapse for 1:1 resonant exoplanets. The atmospheric circulation depends on the planet's rotation rate and orbital configuration and determines the distribution of clouds and hazes. A 3:2 resonant orbit with a theoretically predicted eccentricity of 0.3 changes the stellar irradiation pattern and generally warms the planetary climate. Besides heating and driving circulation, spatially asymmetric energetic radiation from the host star also photolyses molecules, driving the atmospheric composition out of thermochemical equilibrium and motivating the use of 3D coupled Climate-Chemistry Models (CCMs). For 1:1 resonant exoplanets of an Earth-like atmospheric composition, photochemistry driven by M-dwarf radiation can form a global ozone layer, with stellar flares affecting the chemistry and spatial distribution of ozone. The photochemistry is highly sensitive to the stellar flux distribution, in particular at ultraviolet (UV) wavelengths. Other drivers of disequilibrium chemistry such as lightning and circulation as well as the dependence of 3D atmospheric chemistry on the orbital configuration are, as of yet, underexplored. This thesis aims to build upon previous work and investigates the 3D coupled interactions between the physical and chemical processes that govern planetary atmospheres for tidally locked exoplanets around M-dwarfs.
I employ and further develop a 3D CCM -- consisting of the Met Office Unified Model and the UK Chemistry and Aerosols framework -- to simulate the physics and chemistry of exoplanet atmospheres. I configure two tidally locked exoplanets -- nominally Proxima Centauri b and TRAPPIST-1 d -- that are known to exhibit distinct circulation regimes, assuming 1:1 and eccentric 3:2 spin-orbit resonances and Earth-like atmospheric composition (N₂-O₂-CO₂-H₂O). The photochemical simulations consider the Chapman mechanism of ozone formation and the hydrogen oxide (HOₓ) and nitrogen oxide (NOₓ) catalytic cycles of ozone destruction. The CCM was previously used to simulate a 1:1 resonant exoplanet. For this study, I implement the calculation of varying stellar radiation with eccentricity and improve the photochemistry scheme to incorporate the latest stellar spectra in the calculation of spatially and temporally varying photolysis rates. At the time of writing, this is one of only four models able to do these calculations for exoplanets.
In Chapter 3, I demonstrate that using the latest stellar spectrum drives enhanced ozone formation on Proxima Centauri b in a 1:1 spin-orbit resonance with ozone column densities ten times higher than previously found. The global ozone layer shows significant longitudinal variations with an accumulation at the location of permanent nightside gyres. I then investigate the potential for lightning initiation on a tidally locked exoplanet, finding that vigorous convection on the dayside hemisphere results in lightning flash rates (LFR) of up to 0.16 flashes km⁻¹ yr⁻¹, aligning with previously reported cloud coverage. The spatially asymmetric distribution of lightning flashes enhances the dayside hemisphere in NOₓ, which is then advected to the nightside where it reacts to form more complex molecules in the absence of photochemistry. Lightning-induced chemistry is not sufficiently abundant and found too deep in the atmosphere to show detectable features in simulated transmission spectra.
Since the photochemical production of ozone is limited to the dayside hemisphere for 1:1 resonant exoplanets, a connection between the dayside ozone production region and the accumulation of ozone on the nightside has to exist. In Chapter 4, I investigate such dayside-nightside connections and how these explain the longitudinally varying ozone column densities. Transforming from the commonly used geographic to a tidally locked coordinate system to identify inter-hemispheric connections, I find that a stratospheric dayside-to-nightside circulation mechanism transports ozone from the dayside production regions to the nightside, where ozone-rich air then subsides and accumulates at the locations of permanent gyres. With age-of-air tracer experiments, I demonstrate that this circulation mechanism also affects other tracers, as long as the dynamical timescales are shorter than chemical timescales and a stratospheric dayside production mechanism is present.
Chapter 5 compares Proxima Centauri b and TRAPPIST-1 d for both 1:1 and 3:2 spin-orbit resonances, the latter including an eccentricity of 0.3. These planets are known to exhibit distinct circulation regimes for a 1:1 resonance. Regardless of the resonance, TRAPPIST-1 d reaches the runaway greenhouse limit for its true irradiance within 1060 days of simulation. I artificially reduce the irradiance by 22% to ensure a stable climate for the 1:1 resonance, to still investigate the 3D atmospheric chemistry for a planet in this circulation regime. I report stable climates for Proxima Centauri b in both a 1:1 and 3:2 resonance. The 22% reduction in irradiance for TRAPPIST-1 d prevents the runaway greenhouse climate in the 1:1 resonant case. The atmospheric temperature of TRAPPIST-1 d in an eccentric 3:2 resonance increases significantly due to the eccentric orbit and a weaker stabilising cloud feedback, again driving the planet into a runaway greenhouse state. The distributions of ozone for the 3:2 resonant Proxima Centauri b and the 1:1 resonant TRAPPIST-1 d show latitudinal variations in ozone column densities, driven by an equator-to-pole circulation mechanism akin to the Brewer-Dobson circulation that controls the ozone distribution on Earth. Ozone production is stronger on Proxima Centauri b due to a higher UV flux. Ozone destruction is dominated by HOₓ cycling on Proxima Centauri and by NOₓ cycling on TRAPPIST-1 d, resulting from a much higher LFR (up to 1000 flashes km⁻² yr⁻¹) for the latter.
I also demonstrate variability due to the rotation and eccentricity of Proxima Centauri b in a 3:2 spin-orbit resonance in Chapter 5. Especially prominent are the daytime-nighttime and periastron-apoastron cycles in water vapour (H₂O (g)) column densities at 48% and 12%, respectively. Surface temperature and ozone column densities have less pronounced cycles, but all show a brief time lag after periastron and apoastron passages, corresponding to the atmospheric response time. I use the 3D CCM data to generate synthetic emission spectra focusing on the mid-infrared (MIR) range (covered by JWST and also by the concept for the Large Interferometer For Exoplanets or LIFE). The 3D spatial variations and the observed geometry result in spectral fluctuations of up to 36 ppm for the 1:1 resonant exoplanets, depending on the orbital phase angle that we observe. The more homogeneous atmosphere of Proxima Centauri b in a 3:2 spin-orbit resonance lacks spectral fluctuations, presenting a discriminant from the 1:1 case and an important consideration for probing seasonally varying biosignatures.
The thesis highlights the complex 3D interplay in planetary atmospheres between stellar radiation, orbital configuration, atmospheric dynamics, hydrological cycles including cloud formation, lightning initiation, and (photo)chemistry. Chapters 3 and 5 illustrate how the magnitude of ozone production depends on the stellar UV irradiation, but that ozone destruction can be controlled by either the hydrological cycles (producing HOₓ) or lightning initiation (producing NOₓ) and the (photo)chemistry following these processes. Lightning initiation depends on the irradiation and thermodynamics, while orbital parameters like the planet's rotation rate and eccentricity determine the distribution of incoming stellar radiation, in turn also affecting the atmospheric circulation and chemistry. I also illustrate how age-of-air experiments and coordinate system transformations unveil the role of circulation-driven atmospheric chemistry in Chapters 4 and 5, paving the way for further discoveries in climate-dynamics-chemistry interactions as described in Chapter 6. Contrasting the simulations of TRAPPIST-1 d in Chapter 5 underscores the sensitivity of planetary climates to orbital configurations, with implications for habitability studies. Distinct 3D variations in ozone distributions affect potential biosignature interpretation on rocky exoplanets. The presence of spectral fluctuations for the 1:1 resonant cases and the constant spectra for the 3:2 resonant cases provide an important discriminant between both orbital configurations and needs to be considered when studying seasonally varying biosignatures.
I suggest various avenues for further research including 1) climate-dynamics-chemistry interactions, 2) additional disequilibrium chemical processes, 3) habitability for different spin-orbit resonances, 4) intercomparisons for models and (lightning) parametrizations, and 5) prebiotic chemistry in 3D. The 3D variations and potential spectral fluctuations can only be predicted and interpreted using complex 3D CCMs, emphasizing an important role for CCM simulations in developing the science objectives for observatories such as LIFE
The vanishing author in computer-generated works: a critical analysis of recent Australian case law
No full textAbstract
The use of software is ubiquitous in the creation of many copyright works, yet the requirement in copyright law that every work have a human author who engages in independent intellectual effort means that its use may prevent copyright subsistence. Several recent Australian cases have refocused attention on authorship as an essential criterion of copyright subsistence, and these cases suggest that much computer-produced output may be authorless and thus lack copyright protection. This article, the first in a two-part series, analyses how each case deals with the question of authorship of computer-produced works and why the use of software diminishes copyright protection for a significant number of computer-generated works. The article critiques the application of conventional notions of human authorship developed in the pre-computer age to modern productions and suggests alternative approaches to authorship that satisfy both the major objectives of copyright policy and the need to adapt to the computer age. The article argues that, without a broader judicial approach to authorship of computer-generated works, Parliament must remedy the lacuna in protection for these ‘authorless’ works. Possible solutions for reform are suggested. In a forthcoming article, the author comprehensively examines those reform proposals
Diffusive author(s), cohesive author: Analysis of S/N (1994)
No full textThis study indicates the ways in which various aspects of the author(s) are brought forth in Dumb type’s performance art, the S/N production. Previous research has suggested a non-hierarchical organization of Dumb type and the absence of a “privileged author” in Dumb type’s collaborative work, S/N. However, the results that I have investigated from member’s interviews on the creative process of S/N along with my analysis of the recorded images of S/N, indicate a different aspect of the author(s). First, S/N was created through, so to speak, the collective ideas of the members of Dumb type. Further, S/N has at least nine quotations from previous performances, installations, and printed writings, besides the work-in-progress technique. Explicating one of the “author functions” as given by Michel Foucault, each text has plural subjects of the author. However, it has been revealed from members’ interviews that Teiji Furuhashi had a decision-making role in selecting the members’ ideas within the performance. Since then, S/N has had plural subjects of creation; however, Furuhashi is one of the subjects of creation along with the “privileged author.” S/N has plural authors (diffusive authors) yet at the same time, it has a “privileged author,” Teiji Furuhashi (cohesive author)
sj-docx-1-cjk-10.1177_20543581211072330 – Supplemental material for Designing an App for Immunosuppression Adherence and Communication: A Qualitative Approach
No full textSupplemental material, sj-docx-1-cjk-10.1177_20543581211072330 for Designing an App for Immunosuppression Adherence and Communication: A Qualitative Approach by Kara Schick-Makaroff, Laura Lagendyk, Bethany Foster, Ngan N. Lam, Branko Braam, Aminu Bello, Soroush Shojai and Kevin Wen in Canadian Journal of Kidney Health and Disease</p
sj-docx-2-cjk-10.1177_20543581211072330 – Supplemental material for Designing an App for Immunosuppression Adherence and Communication: A Qualitative Approach
No full textSupplemental material, sj-docx-2-cjk-10.1177_20543581211072330 for Designing an App for Immunosuppression Adherence and Communication: A Qualitative Approach by Kara Schick-Makaroff, Laura Lagendyk, Bethany Foster, Ngan N. Lam, Branko Braam, Aminu Bello, Soroush Shojai and Kevin Wen in Canadian Journal of Kidney Health and Disease</p
Yeast at the Crossroads: Nutrient Signalling Paths and Stressful Turns
No full textNutrients serve essential functions as building blocks for cellular components.
Intriguingly, they serve as signalling elements that control basic cellular functions.
In microorganisms such as Saccharomyces cerevisiae, the availability of
nutrients also comes along with further challenges such as fluctuations in
osmolytes, oxygen levels, or pH. Adaptation to these factors requires a coordinated
response from various cellular pathways to ensure survival. This thesis
explores the intersection of nutrient signalling and osmotic stress responses
in S. cerevisiae. Emphasis is placed on (I) the Snf1/Mig1 network, which
regulates the response to carbon source availability, (II) the High Osmolarity
Glycerol (HOG) pathway, governing the osmotic stress response (III) the transcriptional
regulators Nrg1 and Nrg2, whose roles in coordinating nutrientand
osmotic stress responses are not fully understood. Of particular interest
in this study is how cells adapt to lithium ions. Lithium salts have also gained
attention in aging research, yet despite their long history in mood disorder
treatments, their exact effects on cellular signaling remain unclear. We found
that low concentrations of glucose mitigate survival of yeast cells exposed to
lithium chloride. While Nrg1/2 play distinct roles in the response to lithium
chloride exposure, deleting NRG1 markedly increases growth rate in lithium
chloride and glucose. Deletion of both genes confers phenotypic enhancement,
resulting in a distinctive growth pattern with an initial surge and subsequent
drop in growth. Separately, we found fluctuations in shuttling kinetics of Snf1
are influenced by the presence of non-fermentable carbon sources. Additionally,
we employed a genome-wide genetic screen to link mitochondrial gene
expression with nuclear genome regulation, offering new insights into the
crosstalk between cellular subsystems. These findings contribute to our understanding
of the complex crosstalk between nutrient signalling and osmotic
stress responses. By shedding light on the regulatory processes involved in
cellular adaptation, this research adds to our knowledge of how cells respond
to environmental stressors. The implications of these mechanisms extend to
broader biomedical contexts, including aging and age-related diseases such
as metabolic disorders and cancer, where similar signalling pathways play a
critical role
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