Ontological Foundations for Scholarly Debate Mapping Technology

Mapping scholarly debates is an important genre of what can be called Knowledge Domain Analytics (KDA) technology – i.e. technology which combines both quantitative and qualitative methods of analysing specialist knowledge domains. However, current KDA technology research has emerged from diverse traditions and thus lacks a common conceptual foundation. This paper reports on the design of a KDA ontology that aims to provide this foundation. The paper then describes the argumentation extensions to the ontology for supporting scholarly debate mapping as a special form of KDA and demonstrates its expressive capabilities using a case study debate

Stable and Clumped Isotope Characterization of Authigenic Carbonates in Methane Cold Seep Environments

Cold seep environments are characterized by methane-rich fluid migration and discharge at the seafloor. These environments are also intimately linked to microbial communities, which oxidize methane anaerobically, increase alkalinity and promote authigenic carbonate precipitation. We have analyzed a suite of methane-derived authigenic carbonate (MDAC) crusts from the North and Barents Sea using stable and clumped isotopes (δ¹³C, δ¹⁸O, δ⁴⁴Ca, and Δ₄₇) to characterize the sources of fluids as well as the environment of carbonate authigenesis. We additionally assess the potential of MDACs as a Δ₄₇-based paleotemperature archive. The MDACs occur as three main textural-mineralogic types: micritic Mg-calcite cements, micritic aragonite cements and cavity filling aragonite cements. We find that micritic Mg-calcite cements have low δ¹³C_(VPDB) values (−30 to −47‰), high δ⁴⁴Ca_(SW) values (−0.4 to −0.8‰), and Δ₄₇-temperatures (0–6 °C) consistent with shallow sub-seafloor precipitation in isotopic equilibrium. Micritic aragonite cements and cavity filling aragonite cements both have a wider range in δ¹³C_(VPDB) values (−18 to −58‰), lower δ⁴⁴Ca_(SW) values (−0.8 to −1.6‰) and a larger range in Δ₄₇-based apparent temperatures (–2 – 25 °C) with samples displaying equilibrium and disequilibrium clumped isotope values. The range in apparent temperatures as well as δ⁴⁴Ca_(SW) values seen in the aragonite MDACs suggest two kinetic processes: a kinetic isotope effect (KIE) due to the incomplete equilibration of carbon and oxygen isotopes among DIC species from the different sources of DIC (i.e., seawater, methane-sourced DIC and DIC residual to CO₂ degassing or diffusion) and a KIE due to a fast, irreversible precipitation affecting the cations, particularly Ca, bound to carbonate mineral. Our results improve the understanding of kinetic effects on clumped isotope temperatures in MDACs and demonstrate how the multi-isotopic approach combined with textural-mineralogic criteria can be used to identify MDACs for accurate paleotemperature reconstructions

Two Trees: Asset Price Dynamics Induced by Market Clearing

If stocks go up, investors may want to rebalance their portfolios. But investors cannot all rebalance. Expected returns may need to change so that the average investor is still happy to hold the market portfolio despite its changed composition. In this way, simple market clearing can give rise to complex asset market dynamics. We study this phenomenon in a very simple model. Our model has two Lucas trees.' Each tree has i.i.d.dividend growth, and the representative investor has log utility. We are able to give analytical solutions to the model. Despite this simple setup, price-dividend ratios, expected returns, and return variances vary through time. A dividend shock leads to underreaction' in some states, as expected returns rise and prices slowly adjust, and overreaction' in others. Expected returns and excess returns are predictable by price-dividend ratios in the time series and in the cross section, roughly matching value effects and return forecasting regressions. Returns generally display positive serial correlation and negative cross-serial correlation, leading to 'momentuem,' but the opposite signs are possible as well. A shock to one asset's dividend a.ects the price and expected return of the other asset, leading to substantial correlation of returns even when there is no correlation of cash flows and giving the appearance of contagion.' Market clearing allows the inverse portfolio' problem to be solved, in which the weights of the assets in the market portfolio are inverted' to solve for the parameters of the assets' return generating process.

A Lagrangian approach to identifying vortex pinch-off

A criterion for identifying vortex ring pinch-off based on the Lagrangian coherent structures (LCSs) in the flow is proposed and demonstrated for a piston-cylinder arrangement with a piston stroke to diameter (L/D) ratio of ≈ 12. It is found that the appearance of a new disconnected LCS and the termination of the original LCS are indicative of the initiation of vortex pinch-off. The subsequent growth of new LCSs, which tend to roll into spirals, indicates the formation of new vortex cores in the trailing shear layer. Using this criterion, the formation number is found to be 4.1±0.1, which is consistent with the predicted formation number of ≈ 4 of Gharib et al. [ Gharib et al. J. Fluid Mech. 360, 121 (1998) ]. The results obtained using the proposed LCS criterion are compared with those obtained using the circulation criterion of Gharib et al. and are found to be in excellent agreement. The LCS approach is also compared against other metrics, both Lagrangian and Eulerian, and is found to yield insight into the pinch-off process that these do not. Furthermore, the LCS analysis reveals a consistent pattern of coalescing or “pairing” of adjacent vortices in the trailing shear layer, a process which has been extensively documented in circular jets. Given that LCSs are objective and insensitive to local errors in the velocity field, the proposed criterion has the potential to be a robust tool for pinch-off identification. In particular, it may prove useful in the study of unsteady and low Reynolds number flows, where conventional methods based on vorticity prove difficult to us

Znajomość zachowań widowni na podstawie danych statystycznych: Londyn i Amsterdam w połowie lat 30. XX wieku

Publikacja została sfinansowana ze środków Narodowego Programu Rozwoju Humanistyki w ramach projektu nr 12H 11 0004 8

Nested contour dynamics models for axisymmetric vortex rings and vortex wakes

Inviscid models for vortex rings and dipoles are constructed using nested patches of vorticity. These models constitute more realistic approximations to experimental vortex rings and dipoles than the single-contour models of Norbury and Pierrehumbert, and nested contour dynamics algorithms allow their simulation with low computational cost. In two dimensions, nested-contour models for the analytical Lamb dipole are constructed. In the axisymmetric case, a family of models for vortex rings generated by a piston–cylinder apparatus at different stroke ratios is constructed from experimental data. The perturbation response of this family is considered by the introduction of a small region of vorticity at the rear of the vortex, which mimics the addition of circulation to a growing vortex ring by a feeding shear layer. Model vortex rings are found to either accept the additional circulation or shed vorticity into a tail, depending on the perturbation size. A change in the behaviour of the model vortex rings is identified at a stroke ratio of three, when it is found that the maximum relative perturbation size vortex rings can accept becomes approximately constant. We hypothesise that this change in response is related to pinch-off, and that pinch-off might be understood and predicted based on the perturbation responses of model vortex rings. In particular, we suggest that a perturbation response-based framework can be useful in understanding vortex formation in biological flows

Migration Versus Immobility, and Ties to Parents

We investigate the association between geographic proximity to parents and the likelihood of moving longer distances (e.g. at least 40 km), using British panel data from the Understanding Society study and probit regression. We also look at the extent to which this association diminishes by introducing measures of frequency of contact, interaction with neighbors and length of residence. Using a number of different models and samples, we find that living far from parents increases longer distance mobility. Seeing parents weekly and more interactions with neighbors reduce longer distance mobility, but its association with parental proximity remains substantial. The positive effect of living far from parents on the likelihood of moving longer distances is also found in subsamples of those who have lived in their current residence for 5 years or less and of the highly educated, while the negative effect of seeing parents weekly is also found in these subsamples as well as in a subsample of those living close to parents. Even though endogeneity cannot be ruled out completely, these findings show a robust association between family ties and the likelihood of moving a long distance

Reflections on the Venezuelan Transition from a Capitalist Representative to a Socialist Participatory Democracy: What Are Planners to Do?

Venezuela is experiencing a transitional political process in which the government and the majority of Venezuelans want to move from a capitalist representative democracy to a more socialist participatory democracy. This transition is enmeshed in complexities, contradictions, and political opposition. Reflection on the experience of accompanying neighborhood groups in local decision making in Caracas from 2002 to 2006 suggests that planning practitioners and scholars can be allies in the grassroots processes of empowerment and self-determination of local communities and advocates and active agents in the "trickling-up" of greater planning participation to upper levels of government