Austrian Academy of Sciences
Elektronisches Publikationsportal der Österreichischen Akademie der WissenschaftenNot a member yet
51101 research outputs found
Sort by
Agglomeration and population ageing in a two region model of exogenous growth
No full textThis article investigates the effects of introducing demography into the New EconomicGeography. We generalize the constructed capital approach, which relies on infinite individualplanning horizons, by introducing mortality. The resulting overlapping generation frameworkwith heterogeneous individuals allows us to study the effects of ageing on agglomerationprocesses by analytically identifying the level of trade costs that triggers catastrophicagglomeration. Interestingly, this threshold value is rather sensitive to changes in mortality. Inparticular, the introduction of a positive mortality rate makes the symmetric equilibrium morestable and therefore counteracts agglomeration tendencies. In sharp contrast to other NewEconomic Geography approaches, this implies that deeper integration is not necessarilyassociated with higher interregional inequality
Estimating the time-dependent contact rate of SIR and SEIR models in mathematical epidemiology using physics-informed neural networks. ETNA - Electronic Transactions on Numerical Analysis
No full textThe course of an epidemic can often be successfully described mathematically using compartment models. These models result in a system of ordinary differential equations. Two well-known examples are the SIR and the SEIR models. The transition rates between the different compartments are defined by certain parameters that are specific for the respective virus. Often, these parameters are known from the literature or can be determined using statistics. However, the contact rate or the related effective reproduction number are in general not constant in time and thus cannot easily be determined. Here, a new machine learning approach based on physics-informed neural networks is presented that can learn the contact rate from given data for the dynamical systems given by the SIR and SEIR models. The new method generalizes an already known approach for the identification of constant parameters to the variable or time-dependent case. After introducing the new method, it is tested for synthetic data generated by the numerical solution of SIR and SEIR models. The case of exact and perturbed data is considered. In all cases, the contact rate can be learned very satisfactorily. Finally, the SEIR model in combination with physics-informed neural networks is used to learn the contact rate for COVID-19 data given by the course of the epidemic in Germany. The simulation of the number of infected individuals over the course of the epidemic, using the learned contact rate, shows a very promising accordance with the data
Visualising Migration Flow Data with Circular Plots
No full textEffective visualisations of migration flows can substantially enhance our understandingof underlying patterns and trends. However, commonly used migration maps thatshow place-to-place flows as stroked lines drawn atop a geographic map fall short ofconveying the complexities of human movement in a clear and compelling manner.We introduce circular migration plots, a new method for visualising and exploringmigration flow tables in an intuitively graspable way. Our approach aims to providedetailed quantitative information on the intensities and patterns of migration flowsaround the globe by using a visualization design that is effective and visually appealing.The key elements of the design are (a) the arrangement of origins and destinations ofmigration flows in a circular layout, (b) the scaling of individual flows to allow theentire system to be shown simultaneously, (c) the expression of the volume of movementthrough the width of the flow and its direction through the colour of the origin.Drawing on new estimates of 5-year bilateral migration flows between 196 countries,we demonstrate how to create circular migration plots at regional and country levelsusing three alternative software packages: Circos, R, and the JavaScript library d3.js.Circular migration plots considerably improve our ability to graphically evaluatecomplex patterns and trends in migration flow data, and for communicating migrationresearch to scientists in other disciplines and to the general public. Our visualisationmethod is applicable to other kinds of flow data, including trade and remittances flows
Rezension - Werner Zanier (Hrsg.), Kulturwandel um Christi Geburt: Spätlatène- und frühe römische Kaiserzeit in den mittleren Alpen zwischen Südbayern und Gardasee. Akten des Kolloquiums in Innsbruck am 18. und 19. Oktober 2017. Münchner Beiträge zur Vor- und Frühgeschichte 67 (Verlag C. H. Beck, München 2019). Archaeologia Austriaca|Archaeologia Austriaca Band 105/2021 Band 105/2021|
No full textNot just a Return to the patrios politeia – Or How to Turn Ten into Twelve: Response to Ilias Arnaoutoglou. Akten der Gesellschaft für Griechische und Hellenistische Rechtsgeschichte|(28) Symposion 2019 Akten der Gesellschaft für griechische und hellenistische Rechtsgeschichte Band 28|
No full textEin Vergleich der Ergebnisse der ersten Welle des Österreichischen „Survey of Health, Ageing and Retirement in Europe“ (SHARE) und der „Österreichischen Gesundheitsbefragung“ (ATHIS)
No full textTo anticipate future challenges that arise from the ageing society in Austria, it is necessary toanalyse already today the health of elderly people. Currently, two datasets are available forthis purpose, namely the Survey of Health, Ageing and Retirement in Europe (SHARE) andthe Austrian Health Interview Survey (ATHIS). In a first part, the present study depicts aqualitative comparison of both questionnaires concerning the coverage of the state of health,health behaviour and health care utilisation. In a second, it presents a comparison ofdescriptive findings for persons aged 50 years and more regarding the prevalence of variouschronic diseases. A comparison of the included questions shows that both surveys are indifferent ways adaptive to the requirements of elderly people. Yet the benefit of SHARE isthat it captures the socio-demographic circumstances of elderly people much more broadlythan ATHIS. Moreover, SHARE allows a dynamic analysis of the ageing process due to itslongitudinal design. The results of descriptive analyses reveal a higher prevalence for mostdiagnoses of chronic diseases in ATHIS. Certain diseases—like cancer or osteoporosis—tendto be underrepresented in SHARE. In general, the persons interviewed in SHARE tend to behealthier than those included in ATHIS. The higher level of education of the SHARE samplemight only partly explain this discrepancy
Monte Carlo estimators for the Schatten p-norm of symmetric positive semidefinite matrices. ETNA - Electronic Transactions on Numerical Analysis
No full textWe present numerical methods for computing the Schatten p-norm of positive semi-definite matrices. Our motivation stems from uncertainty quantification and optimal experimental design for inverse problems, where the Schatten p-norm defines a measure of uncertainty. Computing the Schatten p-norm of high-dimensional matrices is computationally expensive. We propose a matrix-free method to estimate the Schatten p-norm using a Monte Carlo estimator and derive convergence results and error estimates for the estimator. To efficiently compute the Schatten p-norm for non-integer and large values of p, we use an estimator using Chebyshev polynomial approximations and extend our convergence and error analysis to this setting as well. We demonstrate the performance of our proposed estimators on several test matrices and in an application to optimal experimental design for a model inverse problem
Biocultural resistance and re-existence through a dialogue of knowledges and citizen art in a threatened biosphere reserve. eco.mont (Journal on Protected Mountain Areas Research and Management)|eco.mont Vol. 13 special issue 2021|
No full textBiosphere Reserves face huge challenges worldwide, especially those located in metropolitan areas such as La Campana-Peñuelas Biosphere Reserve in central Chile. As well as direct threats, such as urban sprawl and wildfires, such reserves face a less evident threat in the form of weak community engagement and awareness of the value, opportunities and challenges that the name biosphere reserve offers. Since 2015, environmental conflicts have intensified in this area of Chile, and counter-movements towards re-territorialization have arisen under the slogan “We are biosphere reserve”. This implies a deep understanding of the imbrications of the lives of humans and more-than-humans in a common territory which face common challenges with regard to the preservation of life and regenerative actions and pathways. In Chile, this local social / political / spiritual movement now converges with a national movement towards recovering sovereignty over common goods through a new Constitution. In this article, we describe a fruitful academia-community dialogue of knowledges created through a series of open-access courses, collaborative mapping, and artistic initiatives developed by citizens, such as textile-making and handcrafts using natural pigments. All of these initiatives come together within the framework of very local geopolitical actions for the preservation of the biocultural landscapes found within the biosphere reserve. We discuss these initiatives as forms of biocultural resistance and re-existence
