13 results on '"Keller, Thomas"'
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2. Virtual Reality at Secondary School -- First Results
- Author
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Keller, Thomas, Glauser, Philipp, Ebert, Nico, and Brucker-Kley, Elke
- Abstract
This paper examines the use of Virtual Reality (VR) at Swiss secondary schools. Despite many years of research, no well-founded data are available on the effects of the technology on children's learning success. It is assumed that VR is compatible with the learning theory of constructivism through the possibility of immersion, interaction, 3D representation and the possibility of adopting several perspectives. To investigate the topic, a vision has been developed for a learning unit within the competence area Nature and Technology on the subject "Plastics and its effects on the environment". Divided into five learning blocks, the learning unit provides the students with knowledge about the structure, production, recycling and environmental consequences with possible approaches to solutions. Ideas for possible VR applications were developed for each of these blocks. The vision was discussed in four interviews with teachers. The VR applications were commented and evaluated by 20 students of the same class. The topic "Environmental Problem Microplastics" selected for implementation is topical, fits into curriculum and is compatible with the specialist areas suitable for VR. In summary, it can be said that VR is still a long way from a nationwide deployment at the Swiss elementary school. Nevertheless, the educational institutions should observe the technology and develop an understanding of its possibilities through pilot tests. [For the complete proceedings, see ED600498.]
- Published
- 2018
3. A case study of an immersive learning unit for German as a second language.
- Author
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Keller, Thomas, Brucker-Kley, Elke, and Schwammel, Philip
- Subjects
GERMAN language ,DESIGN science ,FIELD research ,CURRICULUM frameworks ,VIRTUAL design ,VIRTUAL reality ,ITERATIVE learning control - Abstract
More and more children and adolescents in Switzerland show serious deficits in their German language skills. In order to specifically promote the language skills of students with a non-German first language, special lessons in German as a second language (GasL) are therefore offered in addition to the regular lessons. The aim of this case study is to evaluate the impact of a pedagogically sound immersive virtual reality learning unit for GasL lessons, which offers students the opportunity to actively speak German and to demonstrate this in the context of two GasL lessons. The research design is based on the "Design Science Research Framework". In this context, the virtual reality learning unit was designed as an innovative prototype (artifact) and iteratively improved. The design considered the didactic framework of the official curriculum as well as the eleven general design guidelines for virtual reality learning units in an educational context. The virtual reality learning unit was tested in a field experiment with five students each at an elementary school and at a secondary school. The students found the virtual reality learning unit as a whole attractive and motivating. But there are operational challenges and necessary prerequisites that have to be considered and created in order to pragmatically and sustainably integrate immersive virtual reality learning units into the existing GasL lessons. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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4. Analytical performance of 17 commercially available point-of-care tests for CRP to support patient management at lower levels of the health system.
- Author
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Calarco, Serafina, Fernandez-Carballo, B. Leticia, Keller, Thomas, Weber, Stephan, Jakobi, Meike, Marsall, Patrick, Schneiderhan-Marra, Nicole, and Dittrich, Sabine
- Subjects
POINT-of-care testing ,MEDICAL personnel ,C-reactive protein - Abstract
Accurate and precise point-of-care (POC) testing for C-reactive protein (CRP) can help support healthcare providers in the clinical management of patients. Here, we compared the analytical performance of 17 commercially available POC CRP tests to enable more decentralized use of the tool. The following CRP tests were evaluated. Eight quantitative tests: QuikRead go (Aidian), INCLIX (Sugentech), Spinit (Biosurfit), LS4000 (Lansionbio), GS 1200 (Gensure Biotech), Standard F200 (SD Biosensor), Epithod 616 (DxGen), IFP-3000 (Xincheng Biological); and nine semi-quantitative tests: Actim CRP (ACTIM), NADAL Dipstick (nal von minden), NADAL cassette (nal von minden), ALLTEST Dipstick (Hangzhou Alltest Biotech), ALLTEST Cassette cut-off 10-40-80 (Hangzhou Alltest Biotech), ALLTEST Cassette cut-off 10–30 (Hangzhou Alltest Biotech), Biotest (Hangzhou Biotest Biotech), BTNX Quad Line (BTNX), BTNX Tri Line (BTNX). Stored samples (n = 660) had previously been tested for CRP using Cobas 8000 Modular analyzer (Roche Diagnostics International AG, Rotkreuz, Switzerland (reference standards). CRP values represented the clinically relevant range (10–100 mg/L) and were grouped into four categories (<10 mg/L, 10–40 mg/L or 10–30 mg/L, 40–80 mg/L or 30–80 mg/L, and > 80mg/L) for majority of the semi-quantitative tests. Among the eight quantitative POC tests evaluated, QuikRead go and Spinit exhibited better agreement with the reference method, showing slopes of 0.963 and 0.921, respectively. Semi-quantitative tests with the four categories showed a poor percentage agreement for the intermediate categories and higher percentage agreement for the lower and upper limit categories. Analytical performance varied considerably for the semi-quantitative tests, especially among the different categories of CRP values. Our findings suggest that quantitative tests might represent the best choice for a variety of use cases, as they can be used across a broad range of CRP categories. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
5. Nesting of ground‐nesting bees in arable fields is not associated with tillage system per se, but with distance to field edge, crop cover, soil and landscape context.
- Author
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Tschanz, Philippe, Vogel, Stefan, Walter, Achim, Keller, Thomas, and Albrecht, Matthias
- Subjects
TILLAGE ,GROUND cover plants ,BEES ,ARABLE land ,CROPS ,COVER crops ,SOIL texture - Abstract
Copyright of Journal of Applied Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2023
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6. Eliciting Personal Attitude Changes on Predictive Policing Based on a Multilinear Narrative.
- Author
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Brunner, Manuel, Brucker-Kley, Elke, and Keller, Thomas
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PREDICTIVE policing ,INTERACTIVE fiction ,LAW enforcement ,BELIEF & doubt - Abstract
The Swiss population has an ambivalent attitude towards freedom and security. Predictive policing is taking place precisely in this area of tension and raises concerns. Despite this controversial situation and although the Swiss authorities are among the pioneers of predictive policing in the German-speaking world, there seems to be no standard work that would provide a clear picture of the current situation in Switzerland. The actual impact remains unclear and existing information is targeted at law enforcement experts. This research is motivated by the belief that the nature and potential impact of complex technologies must be communicated to a broad lay audience. By presenting possible consequences of new technologies in a narrative style, they may become more tangible. The research presented in this paper aims to examine the influence of a thought-provoking narrative on self-assessed attitudes towards predictive policing in Switzerland and the technologies involved. To this end, a multilinear and interactive scenario which portrays possible future manifestations of predictive policing was developed and tested in a first field experiment. In order to ensure the plausibility of the narrative, first the state-of-the-art and the factors influencing the future of predictive policing had to be collected and analyzed. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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7. Impact of monovalent cations on soil structure. Part II. Results of two Swiss soils.
- Author
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Farahani, Elham, Emami, Hojat, and Keller, Thomas
- Subjects
MONOVALENT cations ,SOIL structure ,SOIL permeability ,SOIL composition ,POTASSIUM ,SOILS ,CARBON in soils - Abstract
In this study, we investigated the impact of adding solutions with different potassium and sodium concentrations on dispersible clay, water retention characteristics, air permeability, and soil shrinkage behaviour using two agricultural soils from Switzerland with different clay content but similar organic carbon to clay ratio. Three different solutions (including only Na, only K, and the combination of both) were added to soil samples at three different cation ratio of soil structural stability levels, and the soil samples were incubated for one month. Our findings showed that the amount of readily dispersible clay increased with increasing Na concentrations and with increasing cation ratio of soil structural stability. The treatment with the maximum Na concentration resulted in the highest water retention and in the lowest shrinkage capacity. This was was associated with high amounts of readily dispersible clay. Air permeability generally increased during incubation due to moderate wetting and drying cycles, but the increase was negatively correlated with readily dispersible clay. Readily dispersible clay decreased with increasing K, while readily dispersible clay increased with increasing K in Iranian soil (Part I of our study). This can be attributed to the different clay mineralogy of the studied soils (muscovite in Part I and illite in Part II). [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
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8. Long-Term Performance of a Glass Fiber-Reinforced Polymer Truss Bridge.
- Author
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Keller, Thomas, Yu Bai, and Vallée, Till
- Subjects
PEDESTRIANS ,BRIDGES ,SAFETY ,POLYMERS ,GLASS fibers ,VANDALISM - Abstract
In the summer of 2005, after eight years of use as a temporary bridge during the winter, the Pontresina Bridge for pedestrians was transported to the Swiss Federal Institute of Technology Lausanne for a detailed assessment of the structural safety, serviceability, and long-term durability of the bridge. The assessment included a visual inspection, quasistatic testing identical to that performed in 1997, and detailed investigations of material degradation. The visual inspection showed a variety of different local defects and damage such as local crushing caused by impact, local cracks due to inappropriate storage and lifting of the structure, fiber blooming, degradation of cut surfaces, and damage due to vandalism. Comparisons between load tests performed in 1997 and 2005 showed, however, that the structural safety and serviceability of the bridge have not been affected by these local damages. The stiffness of the pultruded shapes remained unchanged, whereas a slight decrease in strength between 13 and 18% was measured, which, however, is not critical when taking into consideration the high effective safety factors. In view of a further service period of 5 years until the next inspection, the visible damages were repaired. This experience showed that the durability is primarily affected by inappropriate constructive detailing and that pultruded glass fiber-reinforced polymer shapes, if correctly manufactured and processed, can offer good long-term performance and durability. [ABSTRACT FROM AUTHOR]
- Published
- 2007
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9. Sewage Sludge Treatment by Hydrothermal Carbonization: Feasibility Study for Sustainable Nutrient Recovery and Fuel Production.
- Author
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Gerner, Gabriel, Meyer, Luca, Wanner, Rahel, Keller, Thomas, Krebs, Rolf, and Reza, M. Toufiq
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SLUDGE management ,HYDROTHERMAL carbonization ,CARBONIZATION ,SEWAGE sludge ,NONRENEWABLE natural resources ,WASTE products ,WASTE recycling - Abstract
Phosphorus recovery from waste biomass is becoming increasingly important, given that phosphorus is an exhaustible non-renewable resource. For the recovery of plant nutrients and production of climate-neutral fuel from wet waste streams, hydrothermal carbonization (HTC) has been suggested as a promising technology. In this study, digested sewage sludge (DSS) was used as waste material for phosphorus and nitrogen recovery. HTC was conducted at 200 °C for 4 h, followed by phosphorus stripping (PS) or leaching (PL) at room temperature. The results showed that for PS and PL around 84% and 71% of phosphorus, as well as 53% and 54% of nitrogen, respectively, could be recovered in the liquid phase (process water and/or extract). Heavy metals were mainly transferred to the hydrochar and only <1 ppm of Cd and 21–43 ppm of Zn were found to be in the liquid phase of the acid treatments. According to the economic feasibility calculation, the HTC-treatment per dry ton DSS with an industrial-scale plant would cost around 608 USD. Between 349–406 kg of sulfuric acid are required per dry ton DSS to achieve a high yield in phosphorus recovery, which causes additional costs of 96–118 USD. Compared to current sewage sludge treatment costs in Switzerland, which range between 669 USD and 1173 USD, HTC can be an economically feasible process for DSS treatment and nutrient recovery. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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10. Immediate effects of wheeling with agricultural machinery on topsoil gas transport properties and their anisotropy.
- Author
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Martínez, Ingrid, Stettler, Matthias, Lorenz, Marco, Brunotte, Joachim, Weisskopf, Peter, Sommer, Marlies, and Keller, Thomas
- Subjects
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TOPSOIL , *AGRICULTURAL equipment , *SOIL mechanics , *ANISOTROPY , *CLAY soils , *ROCK permeability - Abstract
This study quantified the immediate impact of soil deformation caused by agricultural vehicle traffic on the anisotropy of the topsoil pore system and gas transport properties (air permeability, gas diffusivity). A field experiment was conducted with five repeated passes of a two-axle self-propelled agricultural vehicle (wheel load 8 Mg, tyre size: 1050/50 R32, tyre inflation pressure: 100 kPa) on an arable clay soil (crop at the time of the experiment: grass ley) in north-western Switzerland. Undisturbed cylindrical soil cores were collected in non-wheeled areas, at the edge of the wheel rut (i.e., at 0.5 m lateral distance from the centre of the wheel track), and at the centre line of the wheel track. The soil cores (0.1 m diameter, 0.06 m in height) were taken in two directions (vertical and horizontal) in the topsoil (0.1 m depth). Air-filled porosity (ε a), air permeability (k a) and relative gas diffusivity (D p / D 0) were measured at three matric potentials (corresponding to p F 1.5, 2.0, and 2.5, respectively). The vehicle-induced deformation resulted in significantly reduced ε a , k a , D p / D 0 in the topsoil. Air permeability was highly anisotropic in non-wheeled soil, with higher k a in vertical direction. Compaction mainly affected macropores and hence k a at the wet end (p F 1.5), decreased the vertical k a more than the horizontal k a , and consequently, k a became less anisotropic due to compaction. This effect was stronger under the edge of the wheel rut than in the centre of the wheel rut. The anisotropy of D p / D 0 was little affected by the vehicle-induced soil deformation. Our results show that soil deformation due to vehicle traffic not only decreases the gas transport capacity of soil but also changes the anisotropy of air permeability, with consequences on soil aeration and soil-atmosphere gas exchange. • Impacts of wheeling are different under the centre and under the edge of the wheel rut. • Wheeling decreased the gas transport properties and changed the anisotropy. • Air permeability was more affected than gas diffusivity. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
11. Predicting the relative density from on-the-go horizontal penetrometer measurements at some arable top soils in Northern Switzerland.
- Author
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Naderi-Boldaji, Mojtaba, Weisskopf, Peter, Stettler, Matthias, and Keller, Thomas
- Subjects
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SOIL density , *SOIL texture , *SOIL moisture , *SANDY loam soils , *PENETROMETERS - Abstract
This study sought to develop empirical models to predict soil relative density ( ρ rel ) from measurements of horizontal penetrometer resistance (PR) and soil water content ( θ g ) in a wide range of soil textures. This permits the comparison of the state of soil compactness in different soil textures. It was hypothesised that model coefficients would be texture-dependent when soil compactness was expressed as bulk density ( ρ d ) and that a model with constant coefficients could be obtained when soil compactness was expressed in terms of ρ rel (obtained as the ratio of ρ d to reference bulk density ( ρ ref )). Field measurements were conducted in 2014 using a horizontal penetrometer at 0.25 m depth in 10 fields in Switzerland with a wide range of soil textures covering sandy loam, silt loam, loam, clay loam and clay (clay concentration, (CC) = 153–585 g kg −1 and organic matter concentration, (OM) = 9–168 g kg −1 ). At selected locations along the penetrometer measurement transects, cylindrical soil cores were sampled for determination of soil texture, OM, θ g and ρ d . Soil water potential and effective stress ( σ ') were also estimated for each location. Standard Proctor tests were performed on eight soils with variable textures. Proctor density was well described as a function of CC and OM ( R 2 adj = 0.97, RMSE = 0.046 Mg m −3 ) and was used as reference density to obtain ρ rel . From this we developed a model for prediction of ρ rel from PR and σ ′ that allows comparisons between soils without changes in model coefficients. However, σ ' cannot be obtained from on-the-go measurements and the model is therefore of limited value for soil compaction mapping. A model for estimating ρ rel from PR and θ g yielded satisfactory predictions ( R 2 adj = 0.66, RMSE = 3.3%), although θ g is a texture-dependent measure of soil water that cannot be compared across soils. Moreover, ρ d was well predicted from PR and θ g ( R 2 adj = 0.93, RMSE = 0.05 Mg m −3 ), possibly because all our measurements were carried out at similar soil water potential, which implies that θ g carries soil textural information. Future research should test the proposed equations for a wide range of soil water potential values. The findings presented can be of use in developing measurement systems for mapping soil compactness that combine the proposed prediction functions with horizontal penetrometer and water content sensor systems. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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12. Pedoclimatic factors and management determine soil organic carbon and aggregation in farmer fields at a regional scale.
- Author
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Büchi, Lucie, Walder, Florian, Banerjee, Samiran, Colombi, Tino, van der Heijden, Marcel G.A., Keller, Thomas, Charles, Raphaël, and Six, Johan
- Subjects
- *
SOIL management , *CARBON in soils , *ORGANIC farming , *FARMS , *SOIL structure - Abstract
• Conventional fields with and without tillage, and organic with tillage were compared. • Little differences in soil carbon and soil aggregate between cropping systems. • Differences were visible only for the surface layer (0–5 cm depth). • High within-system variability was observed, mainly linked to soil texture. • Good soil quality can be achieved in any system depending on local conditions. The degradation of soil from agricultural land is a major threat to food security and a driver of global changes. Soil conservation systems are thus being promoted and/or adopted worldwide. In this on-farm study conducted in Switzerland, we compared the effect of three cropping systems – conventional with tillage, conventional without tillage (i.e. no-till) and organic farming with tillage – on soil quality. Samples from 60 winter wheat fields belonging to these three systems were analysed for soil carbon concentration, soil aggregate distribution and soil biological properties (microbial carbon and mycorrhizal biomarkers), at three different depths (0–5 cm, 5–20 cm and 20–50 cm). Information about cropping practices was collected through surveys. The main differences in soil properties between systems occurred for the surface layer (0–5 cm depth), with increased soil organic carbon concentration and stock under no-till compared to the conventionally tilled fields. No-till and organic fields showed a higher mean aggregate size and proportion of macroaggregates in the surface layer compared to tilled conventional fields, with a greater amount of carbon in the large macroaggregates. However, large within-system variability was also observed, which tended to override differences between systems. Across systems, clay content, microbial carbon, and the mycorrhizal PFLA biomarkers were the major drivers of soil organic carbon concentration, clay to carbon ratio and carbon accumulation in the large macroaggregate fraction. Aggregation at 0–5 cm was mostly related to tillage depth, while climate variables and especially clay content played a major role for deeper layers. Our results demonstrate that within the constraints set by soil texture and climate, organic agriculture and no-till can contribute to improved soil carbon and aggregation properties. Thus, we advocate for the identification of the main drivers of soil quality in order to inform management and improve soil functioning in agricultural fields in the long term. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
13. Agricultural intensification reduces microbial network complexity and the abundance of keystone taxa in roots.
- Author
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Banerjee S, Walder F, Büchi L, Meyer M, Held AY, Gattinger A, Keller T, Charles R, and van der Heijden MGA
- Subjects
- Agriculture, Glomeromycota genetics, Glomeromycota isolation & purification, Microbial Consortia, Mycorrhizae genetics, Mycorrhizae isolation & purification, Phosphorus metabolism, Soil chemistry, Switzerland, Triticum microbiology, Glomeromycota classification, Mycorrhizae classification, Plant Roots microbiology, Soil Microbiology
- Abstract
Root-associated microbes play a key role in plant performance and productivity, making them important players in agroecosystems. So far, very few studies have assessed the impact of different farming systems on the root microbiota and it is still unclear whether agricultural intensification influences the structure and complexity of microbial communities. We investigated the impact of conventional, no-till, and organic farming on wheat root fungal communities using PacBio SMRT sequencing on samples collected from 60 farmlands in Switzerland. Organic farming harbored a much more complex fungal network with significantly higher connectivity than conventional and no-till farming systems. The abundance of keystone taxa was the highest under organic farming where agricultural intensification was the lowest. We also found a strong negative association (R
2 = 0.366; P < 0.0001) between agricultural intensification and root fungal network connectivity. The occurrence of keystone taxa was best explained by soil phosphorus levels, bulk density, pH, and mycorrhizal colonization. The majority of keystone taxa are known to form arbuscular mycorrhizal associations with plants and belong to the orders Glomerales, Paraglomerales, and Diversisporales. Supporting this, the abundance of mycorrhizal fungi in roots and soils was also significantly higher under organic farming. To our knowledge, this is the first study to report mycorrhizal keystone taxa for agroecosystems, and we demonstrate that agricultural intensification reduces network complexity and the abundance of keystone taxa in the root microbiome.- Published
- 2019
- Full Text
- View/download PDF
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