Kaarel Sikk (University of Luxembourg, C2DH and DGEO)

When? 21^st May 2021, 2 to 3 pm

Where? via Webex (request meeting link by registering to isabelle.piroth@uni.lu or geoffrey.caruso@uni.lu)

Point process modelling provides a framework for exploring systems that can be observed as a set of points. In this study, we studied archaeological settlement patterns with the purpose of isolating regions in landscapes that were suitable for habitation by different populations. We create point process models of the settlement systems of hunter-fisher-gatherer groups (Narva and Combed Ware Culture) and early agrarian communities (Corded Ware Culture) in Stone Age Estonia and compare the spatial structure.

We conceptualize settlement system formation as a point process and develop a first-order point process model representing the environmental suitability for habitation based on geomorphology, soil, and proximity to water. We use MaxEnt and the SDMTune machine learning framework for building the model, variable selection, and estimation. The model is applied to the two communities and the effects of the variables and the resulting spatial patterns compared.

The spatial comparison showed significant differences between the suitable environments for habitation between the two groups. While the hunter-fisher-gatherer population had an entirely shoreline-connected settlement system, the Corded Ware people inhabited the areas further away from water bodies. This resulted in significantly expanded potential space with differing spatial configurations for the incoming agrarian groups but the areas also had a certain overlap.

The results also indicated higher predictive power for hunter-fisher-gatherer sites, which might be caused by a higher variety of agrarian activities, different socio-economic organizations, or effects of the spatial structure of the landscape.

The aim of Quadtrees’ Hubs is to share and discuss research in progress. The hubs are open to anyone interested and somehow familiar with quantitative spatial analysis and modelling and willing to progress with these. Please contact Isabelle Pigeron-Piroth or Geoffrey Caruso for information or to obtain the linnk to the meeting.

On May 21^st, our sixth Quadtrees Hub will take place. The aim is to share and discuss research in progress. Quadtrees’hubs are open to anyone interested and somehow familiar with some quantitative techniques and willing to progress with these. Please contact Isabelle Pigeron-Piroth for information.

When? 21^st May 2021, 2 to 3 pm

Where? via Webex

2-3 pm : Marlène Boura  (University of Luxembourg, DGEO): Towards a spatially explicit urban CO₂ budget. Urban carbon emissions, dispersion and sequestration in Europe

Modelling a steady-state urban carbon balance for 802 European cities at a fine spatial resolution.

Anthropogenic CO2 emissions are downscaled spatially (down to 1 ha) and temporally (from annual to daily) based on the sector of activity, the land use category and the location. Sequestration of CO2 is estimated for different types of urban vegetation, following the IPCC guidelines at the same spatial and temporal resolutions.

For one typical day of each month, we simulate 2 steady-state situations for the CO2 molecules dispersion and capture. The absolute carbon balance and the relative carbon capture (as a percentage of effective anthropogenic emissions) are then computed. The data produced can be used to assess the spatial heterogeneity of the carbon balance within a specific urban area. It can also be used to assess how much of its own emissions an urban area can capture.

The slides from my presentation “Change in Artificial Land Use over time across European Cities: A rescaled radial perspective” can be found here.

Workshops

The first workshop was given by Prof. Nick Holliman of Newcastle University looking at data visualisation and exploring the use of Microsoft Power Bi for visualising data. He also presented some of the data currently being collected in the Newcastle Urban Observatory using censors.

The second workshop explored the use of API’s, what they are and how to use them. This workshop was run by researchers from the Newcastle Urban Observatory. Materials from the API workshop can be found here.

The workshop on Wednesday morning was run by Dr. Robin Lovelace and Dr. Nick Bearman and explored mapping in R. Robin presented some materials from his latest book ‘Geocomputation with R’. More details of the book here. Documents and reproducible code from the GIS mapping in R workshop can be found here.

Finally the last workshop was given by Dr. Laura Hanson along with a number of other researchers and spatial analysts from both the private and public sector.

Conference

One of the main trends I picked up from this conference was the use of visual aids and GIF’s created in R. Any of the presentations which used these presented their research in a particularly powerful way. As researchers one of the biggest challenges is presenting our research in a format which is quick and easy to understand. This can be difficult and sometimes require many graphs, figures and tables to get a point across. Such animations present research in a dynamic way.

R code

From an organisational viewpoint the name badges and reusable coffee cup given out at the start of the conference were two welcome features. The name badges made the first name particularly easy to read without a need to strain your eyes while the coffee cups meant a substantial reduction in disposable coffee cup usage given the approximate 200 attendance.

Twitter

An analysis of the tweets from the conferences reveals some interesting trends. It was not surprising to see the term ‘reproducible’ so high up the list. There is a growing number of publications and producing reproducible research along with the code is fast becoming the norm. Representing the code from R or PyQGIS on GitHub alongside the results that appear in the academic article or conference presentation. It is heartening to see such sharing of knowledge in the geocomputation community and will surely only lead to better outcomes in terms of improved research and evidence for policymakers.Code for carrying this out in R can be found in my GitHub here.

Newcastle

One of the most famous features of Newcastle are the seven bridges which cross the River Tyne ranging in both size and age.

There is also the Newcastle castle and gate house. There is a good mixture in this city of both the new with the historic. Nearby Newcastle is situated Durham Cathedral. Construction started in 1093. The cathedral houses the relics of Saint Cuthbert.

The compactness of the city was evident throughput. Public transport also made it very easy to get around with intercity trains, buses and a metro. The city appears to be going from strength to strength.

The conference dinner took place at St. James’s Park home to Newcastle United FC. The pride of the north east (although I am not sure Sunderland or Middlesbrough fans will agree!!) it has been a trophy less period for the magpies over the last couple of decades despite coming close to breaking Manchester United’s dominance in the mid-nineties under Kevin Keegan. An impressive stadium it has a certain character that a lot of modern stadia lack.

I was involved in two talks, one as a presenter and one as a co-author. The talk format was a 5-minute presentation followed by a 3-minutes questions, which may appear very short (especially while preparing your slides), but forces you to give the core message of your study and to leave the rest for informal talks with your peers… Not bad! So the first talk looked at the influence of exposure to multiple environments, trips purposes and distance on utilitarian walking among older adults, based on the CURHA project (soon to be described on this blog). One of the main results stressed the varying barrier effect of distance on walking by trip purpose. People would be more likely to walk with increasing distance to discretionary activity vs. mandatory ones, as they might be more likely to performed these activities in optimal conditions (good weather, good perceived health, having the time to walk…) and thus, discretionary activities are characterized by a higher flexibility in space and time. The second talk, presented by Pr. Jean-Michel Oppert, examined the differential associations of walking and cycling with obesity markers based on the ACTI-Cités project. The related paper was published earlier this year in Obesity Facts (https://doi.org/10.1159/000488532).

I attended mostly sessions looking at the spatial and environmental determinants of physical activity, intervention on physical activity and measurement of physical activity using new technologies. Among these sessions, I would like to report on a couple of talks that especially caught my attention. The first one was a session on “Air pollution and physical activity”, chaired by Dr. Fiona Bull, who immediately brought back the societal and public health issues at stakes: what to answer when the WHO’s phone rings with India on the line to consult on whether they should maintain or not the marathon given the high levels of air pollution? This session mainly addressed whether exposure to air pollution (while doing sport or physical activity) may modify the positive effect of physical activity on health? The answer was pretty clear: long terms benefits of PA among adults are not erased nor reversed by air pollution, so keep being active! On the top of that, Audrey de Nazelle gave a very informative talk on the exposure to air pollution by transport modes. While individuals spend approximatively 6% of their time in travel, it contributes to 24% of NO² inhalation! However, we should keep in mind that in Europe, pedestrians are the least exposed to air pollution compared to car, bus, and bicycle. And pedestrians might be more flexible than other transport mode to choose their travel path towards roads less saturated by car traffic and therefore less polluted. In a session on impact of places and spaces on physical activity, Dr. Jasper Schipperijn presented a ParkIndex tool to measure the exposure to park and predict the probability of an individual at a specific location to use a park. While in their validation study distance did not seem to predict park use, it confirmed me that the influence of “selective daily mobility” on health behaviors cannot be overlooked and should definitively get more attention by the scientific community.

Slide from Dr. Schipperijn on ParkIndex

Finally, innovative tool to visualize exposure to build environment, simulate changes in the urban environment (i.e. school implementation in a neighborhood), and assess related effects on a large number of health related indicators was presented by Dr. Claire Boulange. The power of communication with stakeholders of such a tool is obvious, and appears as a promising complementary method to assess the relevance of urban planning interventions.

Slide from Dr. Boulange on a simulation to assess the impact of implementing a school in a neighborhood

While a lot of other sessions were highly stimulating, I would like to end this report with the very inspiring talk from Richard Wilkinson “Mind the gap: health inequalities”, who made an irrevocable judgement to the case of social inequalities in physical activity and health, and urged each and every individual present at the conference to tackle the structural causes of physical inactivity, starting with socio-economic inequalities.

Brilliant summary of the major determinants of health issues in our society, by Richard Wilkinson

My first feeling was kind of uncomfortable on the first days with a kind of tabula rasa perspective to research. How can so many and so clever mathematicians and physicists (mostly) really get the grips on the most salient aspects of the research they address, given they seem to apply their skills to so many different topics from one day to the other? The common starting point seemingly being to have a big dataset. If geographers are seen as butterflies by economists (Duranton and Rodríguez-Pose) who think of themselves as lions, what would the latter think of complexity people?! Overall kind of frustration that complexity research seems to lack embedding of their research questions in existing literature. Setting this aspect aside (hoping that embedding is better in written pieces rather than talks) then the quality of the research is definitely overwhelming and reconciling: clarity and simplicity in formulation, clear cut interpretations. Delightful.

Beyond this general impression, the geography oriented research I listened to were definitely great. Not the least was the plenary by Céline Rozenblat from Lausanne on the second day, who entertained us visually and theoretically with a multi-scale network approach. An impressive talk showing a micro understanding of firms location and their role on the global organisation of cities. Very surprising to hear how much of intra-firm interactions are still actually happening within single cities despite the global connections. Also the way she used her empirical results across scales to move from resilience and adaptiveness to the idea of panarchy looked so evident from her work and promising. A specific workshop was then devoted to Open Mole and the computational exploration of models with geographical examples. The SpaceNet workshop also had a couple of talks related to cities (http://spacenet.sci-app.com/), including a very original talk I find by Enzo Nicosia (Queen Mary, London) on street network patterns, taking an areal approach rather than a street graph approach to let the shape of urban blocks emerge. A discovery was also (at least for me) the paper given by Ruiqi Li based on his recent Nature paper. Very dense and rich (too much maybe given again the connection to previous modelling work was rather scarce and details on formulations and parameters absent) presentation that resonates with some of our recent findings with Rémi Lemoy (soon in Env. & Plan. B) on density profiles and previous theoretical work with my S-GHOST fellows (Cavailhès, Frankhauser, Peeters, Thomas, Vuidel) on the emergence of sprawl patterns.

The paroxysm for an urban modeller was then the UrbanSys satellite. A total enjoyment and good occasion to know better the work of Diego Rybski (Potsdam Institute for Climate Impact Research) who shares very similar interests and ways to address intra-urban structures and their scaling.  The perspective offered by Dino Pedreschi (Pisa), although not geographical, finished to convince myself about the relevance of the complex systems research perspective. Not quite the exact quote, but in essence he said: “It is fake news that data driven approach will suffice, it needs theory!”. This is exactly what I wanted to hear! I then felt as a fish in water when presenting after a long long day our empirical research on the scaling of urban land and density profiles (with Rémi Lemoy) and of radial road networks (with Rémi and Estelle Mennicken) to which I adjoined some new set of theoretical simulations to better understand the origins of these structures and their scaling.