| 1. |
- Giesecke, Thomas, et al.
(författare)
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The pace of Holocene vegetation change : testing for synchronous developments
- 2011
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 30:19-20, s. 2805-2814
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Forskningsöversikt (refereegranskat)abstract
- Mid to high latitude forest ecosystems have undergone several major compositional changes during the Holocene. The temporal and spatial patterns of these vegetation changes hold potential information to their causes and triggers. Here we test the hypothesis that the timing of vegetation change was synchronous on a sub-continental scale, which implies a common trigger or a step-like change in climate parameters. Pollen diagrams from selected European regions were statistically divided into assemblage zones and the temporal pattern of the zone boundaries analysed. The results show that the temporal pattern of vegetation change was significantly different from random. Times of change cluster around 8.2, 4.8, 3.7, and 1.2 ka, while times of higher than average stability were found around 2.1 and 5.1 ka. Compositional changes linked to the expansion of Corylus avellana and Alnus glutinosa centre around 10.6 and 9.5 ka, respectively. A climatic trigger initiating these changes may have occurred 0.5 to 1 ka earlier, respectively. The synchronous expansion of C avellana and A. glutinosa exemplify that dispersal is not necessarily followed by population expansion. The partly synchronous, partly random expansion of A. glutinosa in adjacent European regions exemplifies that sudden synchronous population expansions are not species specific traits but vary regionally.
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| 2. |
- Juřičková, Lucie, et al.
(författare)
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Early postglacial recolonisation, refugial dynamics and the origin of a major biodiversity hotspot. A case study from the Malá Fatra mountains, Western Carpathians, Slovakia
- 2018
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Ingår i: Holocene. - : SAGE Publications. - 0959-6836. ; 28:4, s. 583-594
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Tidskriftsartikel (refereegranskat)abstract
- While general trends in Central European postglacial recolonisation dynamics are relatively well known, we often lack studies on intermediate (meta-population, landscape) scales. Such studies are needed to increase our understanding of, for example, the location of refugia; emergence of endemism, rates and trajectories of postglacial migrations; and anthropogenic landscape changes. Here, we focused on the outer Western Carpathian mountain chain Malá Fatra, which is currently characterised by high biodiversity and endemism and is thus considered a likely refugium of the Last Glacial period for the temperate biota of Eastern–Central Europe. We used molluscs and vascular plants as reference taxonomic groups and supported palaeoenvironmental interpretations of their (sub)fossil assemblages using high-resolution geochemical data. Generally, postglacial biotic successions from the study region fit the standard developmental pattern well in Middle and Eastern European uplands. Nevertheless, we found important biogeographically based peculiarities. In total, more than 50 species per (sub)fossil community at the reference site Valča, including 30 woodland species and 11 Carpathian endemites, make site of the highest known Holocene mollusc species diversity in Europe. Our palaeoecological analysis of this long-term biodiversity hotspot suggests that the Western Carpathians were likely an important source of the postglacial recolonisation of Central Europe by forest biota and, at the same time, an area of refugium-based endemism.
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| 3. |
- Lackner, Christian, et al.
(författare)
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Tram to Pedestrian Collisions—Priorities and Potentials
- 2022
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Ingår i: Frontiers in Future Transportation. - : Frontiers Media SA. - 2673-5210. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- To improve mobility in cities in line with environmental goals, in urban traffic, trams represent an increasingly important means of transport. Due to the close interaction with other road users, this makes collisions with trams fairly frequent. This study has investigated accidents between trams and vulnerable road users resulting in personal injury, aimed at identifying priorities for simulating collisions between trams and pedestrians to assess passive safety measures. Tram accident data collection established throughout Europe from multiple sources and with varying degree of details, have been combined and analysed. These analyses comprise risk assessments per km-driven and general tram accident partner and site type evaluations, with more detailed analyses on accident site distance to the closest tram stop and injured body regions, respectively. In total, 7,535 tram-pedestrian accident resulting in 8,802 pedestrian injuries, collected in the year 2000–2021, was analysed. Accident risk ranges from 0.934 accidents per number of tram (million) km-driven, for slight injuries to 0.063 for fatal injuries. Pedestrians represent a large proportion of tram accident collision partners, especially for severe and fatal accidents. In accidents between trams and pedestrians, 3% of reported injuries are fatal, 23% severe and 74% minor. Generally, low-speed accidents close to tram stops often leading to minor injuries were observed to be of significant importance (<20m to the GPS location of a stop). Analysis of accidents was done bases on gender of the pedestrian showing overall similar involvements in accident with slight difference for various age groups and sites. Regardless of injury severity, the most frequently injured body region in accidents involving a tram is the head. Likewise, injuries sustained to the thorax, especially for higher injury severities are of high relevance, followed by injuries to the lower extremities. Based on this study, recommendations for developing reasonable tram-pedestrian accident scenarios for virtual testing can be derived for further optimisation of pedestrian safety of trams.
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| 4. |
- Lagain, Anthony, et al.
(författare)
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Recalibration of the lunar chronology due to spatial cratering-rate variability
- 2024
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Ingår i: Icarus. - : Elsevier. - 0019-1035 .- 1090-2643. ; 411
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Tidskriftsartikel (refereegranskat)abstract
- Cratering chronologies are used to derive the history of planetary bodies and assume an isotropic flux of impactors over the entire surface of the Moon. The impactor population is largely dominated by near-Earth-objects (NEOs) since ∼3.5 billion years ago. However, lunar impact probabilities from the currently known NEO population show an excess of impacts close to the poles compared to the equator as well as a latitudinal dependency of the approach angle of impactors. This is accompanied by a variation of the impact flux and speed with the distance from the apex due to the synchronicity of the lunar orbit around the Earth. Here, we compute the spatial dependency of the cratering rate produced by such variabilities and recalibrate the lunar chronology. We show that it allows to reconcile the crater density measured at mid-latitudes around the Chang'e-5 landing site with the age of the samples collected by this mission. Our updated chronology leads to differences in model ages of up to 30% compared to other chronology systems. The modeled cratering rate variability is then compared with the distribution of lunar craters younger than ∼1 Ma, 1 Ga and 4 Ga. The general trend of the cratering distribution is consistent with the one obtained from dynamical models of NEOs, thus potentially reflecting a nonuniform distribution of orbital parameters of ancient impactor populations, beyond 3.5 Ga ago, i.e., planetary leftovers and cometary bodies. If the nonuniformity of the cratering rate could be tested elsewhere in the Solar System, the recalibrated lunar chronology, corrected from spatial variations of the impact flux and approach conditions of impactors, could be extrapolated on other terrestrial bodies such as Mercury and Mars, at least over the last 3.5 billion years. The modeled cratering rate presented here has strong implications for interpreting results of the Artemis program, aiming to explore the South Pole of our satellite, in particular when it will come to link the radiometric age of the samples collected in this region and the crater density of the sampled units.
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| 5. |
- Mirnig, Alexander G., et al.
(författare)
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External communication of automated shuttles: Results, experiences, and lessons learned from three European long-term research projects
- 2022
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Ingår i: Frontiers Robotics AI. - : Frontiers Media SA. - 2296-9144. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Automated shuttles are already seeing deployment in many places across the world and have the potential to transform public mobility to be safer and more accessible. During the current transition phase from fully manual vehicles toward higher degrees of automation and resulting mixed traffic, there is a heightened need for additional communication or external indicators to comprehend automated vehicle actions for other road users. In this work, we present and discuss the results from seven studies (three preparatory and four main studies) conducted in three European countries aimed at investigating and providing a variety of such external communication solutions to facilitate the exchange of information between automated shuttles and other motorized and non-motorized road users.
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| 6. |
- Robertson, Darrel, et al.
(författare)
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Latitude Variation of Flux and Impact Angle of Asteroid Collisions with Earth and the Moon
- 2021
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Ingår i: The Planetary Science Journal. - : Institute of Physics (IOP). - 2632-3338. ; 2:3
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Tidskriftsartikel (refereegranskat)abstract
- Flux and impact angles were calculated for asteroid collisions with Earth and the Moon, using the latest population models for the distribution of near-Earth objects (NEOs) and precession models to determine the impact probabilities. The calculations predict that the flux of impacts to the poles for Earth is 22% greater than the flux at the equator, and 55% greater for the Moon. Impacts near the equator typically have shallower impact angles with a mode near 30° above the horizontal. Conversely, impacts near the poles are typically steep with a mode close to 65°. Our new analysis updates the previously published results by Le Feuvre & Wieczorek incorporating: (1) an updated debiased distribution of NEOs, and (2) updated collision probabilities that account for Lidov–Kozai precession. The new impact distributions provide an important update to risk models, showing a 7% increase in average population risks from sub-300 m impactors, compared to previous atmospheric entry distributions, mostly due to faster impact velocities.
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