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Sex differences in the association between long-term ambient particulate air pollution and the intestinal microbiome composition of children
No full textThe intestinal microbiome is essential for gastrointestinal and overall health, yet its response to air pollution inchildren remains underexplored. In a study involving 412 young children from the ENVIRONAGE cohort, stoolsamples were analysed via Illumina Miseq sequencing to assess microbiome alpha diversity (observed richness,species evenness, and Shannon diversity) and composition. Exposure to previous year particulate air pollution(black carbon, PM2.5, coarse PM, and PM10) was modeled using high-resolution spatial–temporal interpolationmodels. Multiple linear regression models were adjusted for a priori selected covariables and stratified by sex.Furthermore, we performed a differential relative abundance analysis at family and genus level, while accountingfor the same covariables. Statistically significant effect modification by sex was apparent for severalintestinal alpha diversity indices and air pollutants. In boys, we observed negative associations between particulateair pollution exposure and intestinal microbiome richness (estimates ranging from 5.55 to 9.06 perinterquartile range (IQR) increase in particulate air pollution exposure) and Shannon diversity (estimates rangingfrom 0.058 to 0.095 per IQR increase). Differently, in girls non-significant positive associations wereobserved with species evenness (estimates ranging from 0.019 to 0.020 per IQR increase) and Shannon diversity(estimate 0.065 per IQR increase in black carbon). After multiple testing correction, we reported several bacterialfamilies and genera (Streptococcaceae, Clostridiales Incertae Sedis XIII, Coriobacteriaceae, Streptococcus, and Paraprevotella)to be oppositely associated with particulate air pollution exposure in boys and girls. Our findings showa sex-dependent association between particulate air pollution exposure and intestinal microbiome composition,highlighting boys as potentially more vulnerable to diversity loss associated with childhood exposure to particulatepollution.The intestinal microbiome is essential for gastrointestinal and overall health, yet its response to air pollution inchildren remains underexplored. In a study involving 412 young children from the ENVIRONAGE cohort, stoolsamples were analysed via Illumina Miseq sequencing to assess microbiome alpha diversity (observed richness,species evenness, and Shannon diversity) and composition. Exposure to previous year particulate air pollution(black carbon, PM2.5, coarse PM, and PM10) was modeled using high-resolution spatial–temporal interpolationmodels. Multiple linear regression models were adjusted for a priori selected covariables and stratified by sex.Furthermore, we performed a differential relative abundance analysis at family and genus level, while accountingfor the same covariables. Statistically significant effect modification by sex was apparent for severalintestinal alpha diversity indices and air pollutants. In boys, we observed negative associations between particulateair pollution exposure and intestinal microbiome richness (estimates ranging from 5.55 to 9.06 perinterquartile range (IQR) increase in particulate air pollution exposure) and Shannon diversity (estimates rangingfrom 0.058 to 0.095 per IQR increase). Differently, in girls non-significant positive associations wereobserved with species evenness (estimates ranging from 0.019 to 0.020 per IQR increase) and Shannon diversity(estimate 0.065 per IQR increase in black carbon). After multiple testing correction, we reported several bacterialfamilies and genera (Streptococcaceae, Clostridiales Incertae Sedis XIII, Coriobacteriaceae, Streptococcus, and Paraprevotella)to be oppositely associated with particulate air pollution exposure in boys and girls. Our findings showa sex-dependent association between particulate air pollution exposure and intestinal microbiome composition,highlighting boys as potentially more vulnerable to diversity loss associated with childhood exposure to particulatepollution.A
Advances in agrogeophysics : geophysical monitoring of the fresh-saline water interface in an agricultural field in the Belgian polders
No full textPolders are coastal low-lying areas reclaimed on the sea mainly for agriculture. They are constantly drained by pumps, ditches and subsurface drains. In West-Flanders, Belgium they are composed of a shallow freshwater lens on top of denser saline groundwater. This freshwater lens is essential for crop growth but during dry periods, it can disappear and the saline groundwater can enter the root zone by capillary rise and endanger yield. To prevent this, farmers can use controlled drainage to raise the water table in their field during winter months to increase the freshwater lens thickness. To study the effectiveness of the technique, we monitored three fields with piezometers, resistivity sticks alongside field mapping using electromagnetic induction for three years. The resistivity sticks highlighted lithological differences, but also enabled us to monitor the fresh–saline water interface and the water table accurately. Controlled drainage retained additional rainfall during intense summer precipitation but little effect was observed on the fresh–saline water interface. Soil heterogeneity and past land use of the field seem to have a larger effect on the fresh–saline water interface. Despite the limited effect on the freshwater lens, the value of geophysical methods for monitoring its thickness for field-scale study was demonstrated.Les polders sont des zones gagnées sur la mer, principalement pour l’agriculture. Ils sont constamment drainés. En Flandre occidentale, en Belgique, ils sont constitués d’une lentille d’eau douce peu profonde sur une nappe phréatique saline. Cette lentille d’eau douce est essentielle à la croissance des cultures, mais pendant les périodes sèches, elle peut disparaître et l’eau saline peut remonté jusqu’aux racines et compromettre le rendement. Pour éviter cela, les agriculteurs peuvent utiliser le drainage contrôlé afin d’augmenter l’épaisseur de la lentille d’eau douce. Pour étudier l’efficacité de cette technique, nous avons suivi trois champs à l’aide de piézomètres, de sondes de résistivité et d’une cartographie par induction électromagnétique pendant trois ans. Ces techniques ont mis en évidence les différences lithologiques et ont également permis de surveiller avec précision l’interface eau douce-eau salée et le niveau de la nappe phréatique. Le drainage contrôlé a permis de retenir des précipitations supplémentaires pendant les fortes précipitations estivales, mais peu d’effets ont été observés sur l’interface eau douce-eau salée. L’hétérogénéité du sol et son utilisation antérieure semblent avoir un effet plus important. Malgré cela, la pertinence des méthodes géophysiques pour suivre l’épaisseur de la lentille d’eau douce à l’échelle du champ a été démontrée.Polders are coastal low-lying areas reclaimed on the sea mainly for agriculture. They are constantly drained by pumps, ditches and subsurface drains. In West-Flanders, Belgium they are composed of a shallow freshwater lens on top of denser saline groundwater. This freshwater lens is essential for crop growth but during dry periods, it can disappear and the saline groundwater can enter the root zone by capillary rise and endanger yield. To prevent this, farmers can use controlled drainage to raise the water table in their field during winter months to increase the freshwater lens thickness. To study the effectiveness of the technique, we monitored three fields with piezometers, resistivity sticks alongside field mapping using electromagnetic induction for three years. The resistivity sticks highlighted lithological differences, but also enabled us to monitor the fresh–saline water interface and the water table accurately. Controlled drainage retained additional rainfall during intense summer precipitation but little effect was observed on the fresh–saline water interface. Soil heterogeneity and past land use of the field seem to have a larger effect on the fresh–saline water interface. Despite the limited effect on the freshwater lens, the value of geophysical methods for monitoring its thickness for field-scale study was demonstrated.Les polders sont des zones gagnées sur la mer, principalement pour l’agriculture. Ils sont constamment drainés. En Flandre occidentale, en Belgique, ils sont constitués d’une lentille d’eau douce peu profonde sur une nappe phréatique saline. Cette lentille d’eau douce est essentielle à la croissance des cultures, mais pendant les périodes sèches, elle peut disparaître et l’eau saline peut remonté jusqu’aux racines et compromettre le rendement. Pour éviter cela, les agriculteurs peuvent utiliser le drainage contrôlé afin d’augmenter l’épaisseur de la lentille d’eau douce. Pour étudier l’efficacité de cette technique, nous avons suivi trois champs à l’aide de piézomètres, de sondes de résistivité et d’une cartographie par induction électromagnétique pendant trois ans. Ces techniques ont mis en évidence les différences lithologiques et ont également permis de surveiller avec précision l’interface eau douce-eau salée et le niveau de la nappe phréatique. Le drainage contrôlé a permis de retenir des précipitations supplémentaires pendant les fortes précipitations estivales, mais peu d’effets ont été observés sur l’interface eau douce-eau salée. L’hétérogénéité du sol et son utilisation antérieure semblent avoir un effet plus important. Malgré cela, la pertinence des méthodes géophysiques pour suivre l’épaisseur de la lentille d’eau douce à l’échelle du champ a été démontrée.A
Otolith increments in common sole (Solea solea) reveal fish growth plasticity to temperature
No full textPhenotypic plasticity is a major mechanism allowing organisms to respond to environmental variability. Understanding phenotypic plasticity of organisms to warming is crucial to predict future impacts of climate change. In this study, we investigated fish growth plasticity to temperature using a large archive of otoliths collected from 1960 to 2020, providing growth data over the period 1958-2019, of three common sole (Solea solea) populations: North Sea, Irish Sea, and Bay of Biscay. We used mixed-effects models to partition growth variation into its intrinsic (age, age at capture) and extrinsic (temperature, density, fishing pressure, nutrient) components; to disentangle individual-level plasticity from the population-level response to temperature; and to assess the environmental dependency of growth plasticity. We demonstrated that sole growth plasticity followed the Temperature-Size Rule with increasing juvenile growth and decreasing adult growth at higher temperature. Under favourable conditions for sole growth, the positive response to warming in juvenile fish is stronger while the negative response in adult fish is weaker and the individual plasticity variance is lower. Our study provides additional support for the universality of the Temperature-Size Rule and contributes to our understanding of fish populations' responses to current and future climate change.Phenotypic plasticity is a major mechanism allowing organisms to respond to environmental variability. Understanding phenotypic plasticity of organisms to warming is crucial to predict future impacts of climate change. In this study, we investigated fish growth plasticity to temperature using a large archive of otoliths collected from 1960 to 2020, providing growth data over the period 1958-2019, of three common sole (Solea solea) populations: North Sea, Irish Sea, and Bay of Biscay. We used mixed-effects models to partition growth variation into its intrinsic (age, age at capture) and extrinsic (temperature, density, fishing pressure, nutrient) components; to disentangle individual-level plasticity from the population-level response to temperature; and to assess the environmental dependency of growth plasticity. We demonstrated that sole growth plasticity followed the Temperature-Size Rule with increasing juvenile growth and decreasing adult growth at higher temperature. Under favourable conditions for sole growth, the positive response to warming in juvenile fish is stronger while the negative response in adult fish is weaker and the individual plasticity variance is lower. Our study provides additional support for the universality of the Temperature-Size Rule and contributes to our understanding of fish populations' responses to current and future climate change.A
Sense of belonging defined: a conceptual exploration through a qualitative content analysis of ethnic-minority students’ experiences at university
No full textIt became apparent that academic retention in higher education (HE) is influenced beyond academic factors alone. Given sense of belonging’s (SoB’s) relationship with educational and broader outcomes, researchers have shifted their attention to studying SoB’s role in explaining social inequities in HE. However, there is little research that describes how ethnic-cultural minority (ECM) students themselves define and experience SoB, which questions the validity of currently employed measurement instruments. This study builds on this research by conducting a qualitative content analysis on data from 69 interviews with Flemish (Belgian) ECM students. While SoB matters for all students, ECM-students experience greater concerns due to their social identities, which make them more vulnerable to negative stereotyping. Flanders constitutes a theoretically interesting case as ECM and low-socioeconomic status students are less likely to enroll and more likely to underachieve in HE, despite its relatively open-access HE-system. The findings show the importance of the social domain and to a lesser extent, the personal and academic domain for ECM students in defining SoB. This paper concludes by offering a definition and the development of a conceptual model of university SoB that seeks to capture its universal aspects across diverse contexts and social groups. The conclusion discusses the implications of this study for future research and social policy.It became apparent that academic retention in higher education (HE) is influenced beyond academic factors alone. Given sense of belonging’s (SoB’s) relationship with educational and broader outcomes, researchers have shifted their attention to studying SoB’s role in explaining social inequities in HE. However, there is little research that describes how ethnic-cultural minority (ECM) students themselves define and experience SoB, which questions the validity of currently employed measurement instruments. This study builds on this research by conducting a qualitative content analysis on data from 69 interviews with Flemish (Belgian) ECM students. While SoB matters for all students, ECM-students experience greater concerns due to their social identities, which make them more vulnerable to negative stereotyping. Flanders constitutes a theoretically interesting case as ECM and low-socioeconomic status students are less likely to enroll and more likely to underachieve in HE, despite its relatively open-access HE-system. The findings show the importance of the social domain and to a lesser extent, the personal and academic domain for ECM students in defining SoB. This paper concludes by offering a definition and the development of a conceptual model of university SoB that seeks to capture its universal aspects across diverse contexts and social groups. The conclusion discusses the implications of this study for future research and social policy.A
Bruno Peeters : liber amicorum /
No full textTer gelegenheid van zijn emeritaat bieden de collega’s en vrienden van prof. dr. Bruno Peeters hem dit Liber Amicorum aan. De academische zitting, waar het Liber Amicorum wordt overhandigd, wordt georganiseerd door de Faculteit Rechten van de Universiteit Antwerpen op 20 mei 2025.Professor Peeters heeft meer dan 40 jaar een onschatbare bijdrage geleverd aan het fiscale landschap in België en daarbuiten. Als gewoon hoogleraar, assessor bij de Raad van State en advocaat aan de Antwerpse balie, staat hij bekend om zijn integriteit, betrokkenheid en vernieuwende inzichten.Het Liber Amicorum omvat 2 boekdelen met bijdragen van 80 auteurs. De behandelde thema’s bestrijken het brede domein van de fiscaliteit, gaande van fiscale ethiek en fundamentele rechtsbeginselen tot actuele onderwerpen zoals de Belgische begroting, de OESO-initiatieven rond Pillar II en innovatieve toepassingen van artificiële intelligentie in het fiscaal recht.Dit werk weerspiegelt niet alleen de veelzijdigheid en academische excellentie van professor Peeters, maar ook de diepe waardering van zijn collega’s en allen die het voorrecht hadden met hem samen te werken. (source: publisher's website)Ter gelegenheid van zijn emeritaat bieden de collega’s en vrienden van prof. dr. Bruno Peeters hem dit Liber Amicorum aan. De academische zitting, waar het Liber Amicorum wordt overhandigd, wordt georganiseerd door de Faculteit Rechten van de Universiteit Antwerpen op 20 mei 2025.Professor Peeters heeft meer dan 40 jaar een onschatbare bijdrage geleverd aan het fiscale landschap in België en daarbuiten. Als gewoon hoogleraar, assessor bij de Raad van State en advocaat aan de Antwerpse balie, staat hij bekend om zijn integriteit, betrokkenheid en vernieuwende inzichten.Het Liber Amicorum omvat 2 boekdelen met bijdragen van 80 auteurs. De behandelde thema’s bestrijken het brede domein van de fiscaliteit, gaande van fiscale ethiek en fundamentele rechtsbeginselen tot actuele onderwerpen zoals de Belgische begroting, de OESO-initiatieven rond Pillar II en innovatieve toepassingen van artificiële intelligentie in het fiscaal recht.Dit werk weerspiegelt niet alleen de veelzijdigheid en academische excellentie van professor Peeters, maar ook de diepe waardering van zijn collega’s en allen die het voorrecht hadden met hem samen te werken. (source: publisher's website
Speed and position measurement of rotating machinery with a triangular pattern vision encoder
No full textThe measurement of the position and speed of rotating machinery is essential in the manufacturing industry in order to effectively control a process. Traditional measurement methods such as encoders, resolvers, and tachometers are limited to a single rotating element, require precise (mechanical) installation, and measure on the motor shaft rather than the load. This article proposes a novel methodology to overcome the shortcomings of conventional sensors with a triangular pattern vision encoder. The approach uses single pixellines in combination with a triangular pattern applied to a roller to capture the position and speed of one or more axes simultaneously. First, a preprocessing step detects the position of a roller in the frame. Second, the width of the triangle is detected and mapped to accurately measure the position of the roller. The main contributions are improved robustness compared to state-of-the-art techniques, straightforward multitarget velocity analysis, and the integration of FDZP as a subpixel technique. The proposed design is validated on an industrial web processing machine (WPM) and achieves an accuracy of 480 μ rad, an improvement of approximately 38% over the benchmark incremental optical encoder, which achieves an accuracy of 770 μ rad.The measurement of the position and speed of rotating machinery is essential in the manufacturing industry in order to effectively control a process. Traditional measurement methods such as encoders, resolvers, and tachometers are limited to a single rotating element, require precise (mechanical) installation, and measure on the motor shaft rather than the load. This article proposes a novel methodology to overcome the shortcomings of conventional sensors with a triangular pattern vision encoder. The approach uses single pixellines in combination with a triangular pattern applied to a roller to capture the position and speed of one or more axes simultaneously. First, a preprocessing step detects the position of a roller in the frame. Second, the width of the triangle is detected and mapped to accurately measure the position of the roller. The main contributions are improved robustness compared to state-of-the-art techniques, straightforward multitarget velocity analysis, and the integration of FDZP as a subpixel technique. The proposed design is validated on an industrial web processing machine (WPM) and achieves an accuracy of 480 μ rad, an improvement of approximately 38% over the benchmark incremental optical encoder, which achieves an accuracy of 770 μ rad.A
Profiles of teachers based on self-reported effective teaching behaviour during team teaching : a cluster analysis
No full textNowadays, collaboration between teachers is gaining momentum as a way of improvingteachers’ teaching practice in schools. Team teaching, a collaborative teaching model wheretwo or more teachers teach together, is an innovative approach that has gained increasinginterest. However, very little research exists on effective teaching behaviour in the context ofteam teaching. This study aims to address this gap by identifying different profiles andanalysing differences between them, through a survey study (n = 525). A hierarchical and kmeans cluster analysis revealed two profiles: teachers with an average level and teachers withhigh self-reported effective teaching behaviour during team teaching. Further, significantdifferences between the two profiles were found, in terms of number of colleagues, use of teamteaching, team teaching experiences, team teaching percentage, collaboration, and sharedresponsibility.Nowadays, collaboration between teachers is gaining momentum as a way of improvingteachers’ teaching practice in schools. Team teaching, a collaborative teaching model wheretwo or more teachers teach together, is an innovative approach that has gained increasinginterest. However, very little research exists on effective teaching behaviour in the context ofteam teaching. This study aims to address this gap by identifying different profiles andanalysing differences between them, through a survey study (n = 525). A hierarchical and kmeans cluster analysis revealed two profiles: teachers with an average level and teachers withhigh self-reported effective teaching behaviour during team teaching. Further, significantdifferences between the two profiles were found, in terms of number of colleagues, use of teamteaching, team teaching experiences, team teaching percentage, collaboration, and sharedresponsibility.A
User-specific walking accessibility : addressing the mismatch between calculated and perceived walking accessibility measures
No full textClimate change is one of the main challenges humanity currently faces. To mitigate its severity,the transport sector needs to reduce greenhouse gas emissions. Walking is essential to makethe transport sector more sustainable, as it can be considered the most sustainable means oftransport. In addition, walking is not only a means of transport itself; it is also needed to startand end a trip with any vehicle and is an essential enabler of public transport and sharedmobility. To encourage people to walk, their walking needs must be fulfilled. This includeswalking accessibility through nearby destinations and a walkable infrastructure in terms ofsecurity, safety, comfort, and pleasurability that meets the needs of all.Accessibility instruments are valuable tools for decision support, but for walking, a generalmismatch between calculated and perceived accessibility has been identified. The reason forthis is the neglect of the perceptions of different user groups and the isolated assessment ofaccessibility, with the disregard of walkability elements. This mismatch shows that existingmeasures are unable to model walking accessibility adequately. With the aim of reducing themismatch between perceived and calculated walking accessibility, this dissertation develops atransferable measure for modelling perceived walking accessibility that can be tailored tospecific user groups. Therefore, three research questions arise: “Which walking accessibilitystudies exist, what do they consider and what are they missing?”, “Which attributes have animpact on perceived walking accessibility?” and “How can the variety of perceptions berepresented in feasible, calculated accessibility measures?”.In order to answer these questions, first, a literature review on existing accessibility measureswas carried out, and recommendations for future measures were drawn. Second, a survey onperceived accessibility was conducted and compared with calculated accessibility to explorethe mismatch further. Moreover, the survey results were statistically analysed to betterunderstand the factors that influence perceived accessibility. Finally, a Perceived user-specificAccessibility measure for Walking (PAW) was developed and applied in a case study. TheAnalytic Hierarchy Process (AHP) method was used to determine the weights of differentinfluencing factors for four sample user groups (seniors, children, wheelchair users, women).Findings indicated that conventional calculated accessibility measures do not do justice to thefour accessibility components defined by Geurs and van Wee (2004); in particular, theindividual and temporal components are neglected. Furthermore, they usually do not representthe pedestrian network with all its micro-elements. Impedance is typically determined bydistance or time, whereas perceived walking time is more accurate. By comparing the survey results with the calculated accessibility, the mismatch between perceived and calculatedaccessibility measures was confirmed, highlighting the inability of conventional calculatedaccessibility measures to capture the accessibility as it is perceived by people. Perceivedaccessibility was found to be influenced by many factors: accessibility, walkability, usercharacteristics, geographical context and temporal changes. Following the findings, themeasure PAW was developed. PAW uses imputed perceptions, which are presented as thekey to closing the gap between perceived and measured accessibility. Therewith, theperceived walking times can be inferred by evaluating how well the walking infrastructuremeets the user’s needs. The results show that conventional accessibility measures oftenoverestimate, but sometimes also underestimate, accessibility compared to PAW.However, it has not yet been proven that PAW represents walking accessibility morerealistically than existing measures. PAW fulfils many of the drawn recommendations, butsome decisions in the development process were made in favour of simplicity instead ofaccuracy. The measure focuses on modelling the individual component and its interplay withthe transport component; thereby, the temporal component is excluded, and the land-usecomponent is only considered partially. The factors influencing perceived walking accessibilityare understood better but cannot be considered conclusive, as the interdependencies arecomplex. Four user groups have been studied in the development of PAW. However, theseare only examples. PAW can be adapted to any user group and transferred to study areasworldwide. But it should be noted that the measure results can only be as good as the inputdata.This research has contributed to the overall understanding of walking accessibility and canhelp to increase the awareness of walking needs and apply these findings to planning practice.The gap between perceived and calculated accessibility measures has not been completelyclosed, but presumably narrowed.Public defense: 2025-02-12Climate change is one of the main challenges humanity currently faces. To mitigate its severity,the transport sector needs to reduce greenhouse gas emissions. Walking is essential to makethe transport sector more sustainable, as it can be considered the most sustainable means oftransport. In addition, walking is not only a means of transport itself; it is also needed to startand end a trip with any vehicle and is an essential enabler of public transport and sharedmobility. To encourage people to walk, their walking needs must be fulfilled. This includeswalking accessibility through nearby destinations and a walkable infrastructure in terms ofsecurity, safety, comfort, and pleasurability that meets the needs of all.Accessibility instruments are valuable tools for decision support, but for walking, a generalmismatch between calculated and perceived accessibility has been identified. The reason forthis is the neglect of the perceptions of different user groups and the isolated assessment ofaccessibility, with the disregard of walkability elements. This mismatch shows that existingmeasures are unable to model walking accessibility adequately. With the aim of reducing themismatch between perceived and calculated walking accessibility, this dissertation develops atransferable measure for modelling perceived walking accessibility that can be tailored tospecific user groups. Therefore, three research questions arise: “Which walking accessibilitystudies exist, what do they consider and what are they missing?”, “Which attributes have animpact on perceived walking accessibility?” and “How can the variety of perceptions berepresented in feasible, calculated accessibility measures?”.In order to answer these questions, first, a literature review on existing accessibility measureswas carried out, and recommendations for future measures were drawn. Second, a survey onperceived accessibility was conducted and compared with calculated accessibility to explorethe mismatch further. Moreover, the survey results were statistically analysed to betterunderstand the factors that influence perceived accessibility. Finally, a Perceived user-specificAccessibility measure for Walking (PAW) was developed and applied in a case study. TheAnalytic Hierarchy Process (AHP) method was used to determine the weights of differentinfluencing factors for four sample user groups (seniors, children, wheelchair users, women).Findings indicated that conventional calculated accessibility measures do not do justice to thefour accessibility components defined by Geurs and van Wee (2004); in particular, theindividual and temporal components are neglected. Furthermore, they usually do not representthe pedestrian network with all its micro-elements. Impedance is typically determined bydistance or time, whereas perceived walking time is more accurate. By comparing the survey results with the calculated accessibility, the mismatch between perceived and calculatedaccessibility measures was confirmed, highlighting the inability of conventional calculatedaccessibility measures to capture the accessibility as it is perceived by people. Perceivedaccessibility was found to be influenced by many factors: accessibility, walkability, usercharacteristics, geographical context and temporal changes. Following the findings, themeasure PAW was developed. PAW uses imputed perceptions, which are presented as thekey to closing the gap between perceived and measured accessibility. Therewith, theperceived walking times can be inferred by evaluating how well the walking infrastructuremeets the user’s needs. The results show that conventional accessibility measures oftenoverestimate, but sometimes also underestimate, accessibility compared to PAW.However, it has not yet been proven that PAW represents walking accessibility morerealistically than existing measures. PAW fulfils many of the drawn recommendations, butsome decisions in the development process were made in favour of simplicity instead ofaccuracy. The measure focuses on modelling the individual component and its interplay withthe transport component; thereby, the temporal component is excluded, and the land-usecomponent is only considered partially. The factors influencing perceived walking accessibilityare understood better but cannot be considered conclusive, as the interdependencies arecomplex. Four user groups have been studied in the development of PAW. However, theseare only examples. PAW can be adapted to any user group and transferred to study areasworldwide. But it should be noted that the measure results can only be as good as the inputdata.This research has contributed to the overall understanding of walking accessibility and canhelp to increase the awareness of walking needs and apply these findings to planning practice.The gap between perceived and calculated accessibility measures has not been completelyclosed, but presumably narrowed.D
Feed additives for methane mitigation : recommendations for identification and selection of bioactive compounds to develop antimethanogenic feed additives
No full textDespite the increasing interest in developing antimethanogenic additives to reduce enteric methane (CH4) emissions and the extensive research conducted over the last decades, the global livestock industry has a very limited number of antimethanogenic feed additives (AMFA) available that can deliver substantial reduction, and they have generally not reached the market yet. This work provides technical recommendations and guidelines for conducting tests intended to screen the potential to reduce, directly or indirectly, enteric CH4 of compounds before they can be further assessed in in vivo conditions. The steps involved in this work cover the discovery, isolation, and identification of compounds capable of affecting CH4 production by rumen microbes, followed by in vitro laboratory testing of potential candidates. The finding of new bioactive compounds as AMFA can be based on 2 approaches: empirical and mechanistic. The empirical approach involves obtaining and screening compounds present in databases and repositories that potentially possess the desired effect but have not yet been tested, screening natural sources of secondary compounds such as plants, fungi, and algae for their antimethanogenic effects, or examining compounds with antimethanogenic effect on microbes in other research domains outside the rumen. In contrast, the mechanistic approach is the theoretical process of discovery new bioactive compounds based on existing knowledge of a biological target or process. The in vitro methodologies reviewed include examining effects at the subcellular level, in single pure cultures of methanogens and examining in more complex mixed rumen microbial populations. Simple in vitro methodologies (subcellular assessments and batch culture) allow testing a large number of compounds, whereas more complex systems simulating the rumen microbial ecosystem can test a limited number of candidates but provide better insight about the antimethanogenic efficacy. This work collated the main advantages, limitations, and technical recommendations associated with each step and methodology use during the identification and screening of AMFA candidates.Despite the increasing interest in developing antimethanogenic additives to reduce enteric methane (CH4) emissions and the extensive research conducted over the last decades, the global livestock industry has a very limited number of antimethanogenic feed additives (AMFA) available that can deliver substantial reduction, and they have generally not reached the market yet. This work provides technical recommendations and guidelines for conducting tests intended to screen the potential to reduce, directly or indirectly, enteric CH4 of compounds before they can be further assessed in in vivo conditions. The steps involved in this work cover the discovery, isolation, and identification of compounds capable of affecting CH4 production by rumen microbes, followed by in vitro laboratory testing of potential candidates. The finding of new bioactive compounds as AMFA can be based on 2 approaches: empirical and mechanistic. The empirical approach involves obtaining and screening compounds present in databases and repositories that potentially possess the desired effect but have not yet been tested, screening natural sources of secondary compounds such as plants, fungi, and algae for their antimethanogenic effects, or examining compounds with antimethanogenic effect on microbes in other research domains outside the rumen. In contrast, the mechanistic approach is the theoretical process of discovery new bioactive compounds based on existing knowledge of a biological target or process. The in vitro methodologies reviewed include examining effects at the subcellular level, in single pure cultures of methanogens and examining in more complex mixed rumen microbial populations. Simple in vitro methodologies (subcellular assessments and batch culture) allow testing a large number of compounds, whereas more complex systems simulating the rumen microbial ecosystem can test a limited number of candidates but provide better insight about the antimethanogenic efficacy. This work collated the main advantages, limitations, and technical recommendations associated with each step and methodology use during the identification and screening of AMFA candidates.A