9,415 research outputs found
The phenomenology of electric dipole moments in models of scalar leptoquarks
We study the phenomenology of electric dipole moments (EDMs) induced in
various scalar leptoquark models. We consider generic leptoquark couplings to
quarks and leptons and match to Standard Model effective field theory. After
evolving the resulting operators to low energies, we connect to EDM experiments
by using up-to-date hadronic, nuclear, and atomic matrix elements. We show that
current experimental limits set strong constraints on the possible CP-violating
phases in leptoquark models. Depending on the quarks and leptons involved in
the interaction, the existing searches for EDMs of leptons, nucleons, atoms,
and molecules all play a role in constraining the CP-violating couplings. We
discuss the impact of hadronic and nuclear uncertainties as well as the
sensitivities that can be achieved with future EDM experiments. Finally, we
study the impact of EDM constraints on a specific leptoquark model that can
explain the recent -physics anomalies.Comment: Published versio
Divergent roles of CprK paralogues from Desulfitobacterium hafniense in activating gene expression
Gene duplication and horizontal gene transfer play an important role in the evolution of prokaryotic genomes. We have investigated the role of three CprK paralogues from the cAMP receptor protein-fumarate and nitrate reduction regulator (CRP-FNR) family of transcriptional regulators that are encoded in the genome of Desulfitobacterium hafniense DCB-2 and possibly regulate expression of genes involved in the energy-conserving terminal reduction of organohalides (halorespiration). The results from in vivo and in vitro promoter probe assays show that two regulators (CprK1 and CprK2) have an at least partially overlapping effector specificity, with preference for ortho-chlorophenols, while meta-chlorophenols proved to be effectors for CprK4. The presence of a potential transposase-encoding gene in the vicinity of the cprK genes indicates that their redundancy is probably caused by mobile genetic elements. The CprK paralogues activated transcription from promoters containing a 14 bp inverted repeat (dehalobox) that closely resembles the FNR-box. We found a strong negative correlation between the rate of transcriptional activation and the number of nuclecitide changes from the optimal dehalobox sequence (TTAAT-N-4-ATTAA). Transcription was initiated by CprK4 from a promoter that is situated upstream of a gene encoding a methyl-accepting chemotaxis protein. This might be the first indication of taxis of an anaerobic bacterium to halogenated aromatic compounds
Determinants of soil organic matter chemistry in maritime temperate forest ecosystems
While the influence of climate, vegetation, management and abiotic site factors on total carbon budgets and turn-over is intensively assessed, the influences of these ecosystem properties on the chemical complexity of soil organic matter (SOM) remains poorly understood. This study addresses the chemical composition of NaOH-extracted SOM from maritime temperate forest sites in Flanders (Belgium) by pyrolysis-GC/MS. The studied forests were chosen based on dominant tree species (Pinus sylvestris, Fagus sylvatica, Quercus robur and Populus spp.), soil texture and soil-moisture conditions. Differences in extractable-SOM pyrolysis products were correlated to site variables including dominant tree species, management of the woody biomass, site history, soil properties, total carbon stocks and indicators for microbial activity. Despite of a typical high intercorrelation between these site variables, the influence of the dominant tree species is prominent. The extractable-SOM composition is strongly correlated to litter quality and available nutrients. In nutrient-poor forests with low litter quality, the decomposition of relatively recalcitrant compounds (i.e. short and mid-chain alkanes/alkenes and aromatic compounds) appears hampered, causing a relative accumulation of these compounds in the soil. However, if substrate quality is favorable, no accumulations of recalcitrant compounds were observed, not even under high soil-moisture conditions. Former heathland vegetation still had a profound influence on extractable-SOM chemistry of young pine forests after a minimum of 60 year
Exploration of the taxonomy of some Pleistocene Cervini (Mammalia, Artiodactyla, Cervidae) from Java and Sumatra (Indonesia): a geometric- and linear morphometric approach
Third molars of extant- and fossil Southeast Asian deer were metrically compared using a linear- and geometric morphometric approach and discussed in relation to known taxonomic information from the literature. Our analysis suggests the presence of medium sized deer of the genus Axis and large sized taxa of the genus Cervus s. l. in Java. Axis lydekkeri and Axis javanicus are considered valid taxa, with A. lydekkeri probably related to the subgenus Hyelaphus. The large deer, such as Cervus kendengensis, Cervus stehlini and Cervus problematicus are most likely of the subgenus Rusa, the former two closely related to extant Cervus timorensis. The Sumatran fossils are members of the subgenus Rusa, but not necessarily conspecific with extant Cervus (Rusa) unicolor
The Impact Of Tax Benefit Systems On Low Income Households In The Benelux Countries. A Simulation Approach Using Synthetic Datasets
Computing the tax-benefit position of similar typical households across countries is a method widely used in comparative fiscal- and social policy research. These calculations provide convenient summary pictures of certain aspects of tax-benefit systems. They can, however, be seriously misleading because they reduce very complex systems to single point estimates. Using an integrated European tax-benefit model (EUROMOD), we substitute the typical household by a synthetic dataset, which can be used across countries. By varying certain important household characteristics (notably income), this dataset captures a much larger range of household situations. The calculations performed on this range of households not only show the tax-benefit position of many individual households but also demonstrate which household characteristics determine taxes and benefits in each country. Hypothetical calculations such as those presented here do not exploit the ability of EUROMOD to determine the impact of social and fiscal policies on actual populations. Nevertheless, they can be a valuable contribution to understanding tax-benefit systems since they allow us to separate the effects of tax-benefit rules from those of the population structure. We compute and compare disposable incomes for a large range of pre-tax-and-benefit income (so called budget constraints) of households in the Benelux countries. Disposable incomes are then decomposed to separately show the effects of each simulated tax and transfer payment. Based on these results, we illustrate the performance of the three tax-benefit systems in terms of ensuring a minimum level of household income.European Union, Microsimulation, Poverty, Benelux, Average Production Worker
Examining the spatially heterogeneous effects of the built environment on walking among older adults
Understanding the relationship between the built environment and walking among older adults could offer important insights for land use and transport policies which seek to promote active ageing. However, most previous studies have explored global relationships, i.e. the effects are averaged or assumed to be constant over the region of interest. In this study, we focus on the local spatial variations in the relationship between the built environment and the daily time spent walking by older adults. We apply a geographically weighted regression (GWR) model, using data collected from 702 older adults in Nanjing, China. Our results show that spatial heterogeneity exists for built environment effects within the entire study area. It has an impact on all the relationships, with nuances in the significance level, parameter magnitude or sign reversals, depending on the location. Therefore, policy interventions would only be effective in certain areas for certain built environment attributes. By exploring the local contexts of relationships, we further suggest that the spatial heterogeneity stems from contextual effects, i.e. the specificities of places with a discriminative composition of individual and/or environmental characteristics. Our findings can help to enrich the understanding of associations between land use and travel behaviour, as well as offer local planning guidance for creating age-friendly neighbourhoods
Sustainable transport modes, travel satisfaction, and emotions: Evidence from car-dependent compact cities
This study investigates how the use of sustainable transport modes relates to travel satisfaction (general evaluation of travel) and travel affect (emotions during travel) in car-dependent compact cities. Thereby, the study provides evidence on sustainable mobility and travel-related well-being in a context of compact urban form but inadequate provisions for public transport, walking, and cycling. A mixed-methods approach was applied comprising quantitative and qualitative analyses of data from the two major cities of Greece, i.e., Athens and Thessaloniki. Travel satisfaction and travel affect are found to be highest for those who walk for commuting, independently of travel time and other factors. Conversely, travel satisfaction and travel affect are lowest for public transport users, largely due to very long travel times but also poor public transport services in one of the two cities. Results indicate that the experience of traveling by public transport, car, and motorcycle within urban areas greatly depends on transport provision and policies. Overall, findings support the idea that to shift to pleasant, satisfying, and sustainable mobility in car-dependent compact cities, car restrictions should be accompanied by massive improvements in public transport, high-quality walking and cycling infrastructure, and an integrated coordination of different modes
Do e-shopping attitudes mediate the effect of the built environment on online shopping frequency of e-shoppers?
It is widely acknowledged that e-shopping has considerable effects on e-shoppers’ travel behavior. Therefore, it is valuable to investigate the built environment effects on online shopping, which can help clarify whether land use policy is effective to manage online shopping and further moderate travel demand. However, this issue has not been fully investigated in prior research. In particular, some existing studies fail to identify a significant link between the built environment and online shopping. One of the possible reasons is that the indirect effects of the built environment on e-shopping through e-shopping attitudes are rarely considered. Against this backdrop, considering the mediating role of e-shopping attitudes, this paper aims to explore the influence of the built environment on the frequency of e-shopping for clothes and shoes, food and drinks, cosmetics, and electronics. Data used in this study are acquired from 675 face-to-face interviews with online buyers in Chengdu, China, and the Structural Equation Modeling method is employed. The outcomes show that higher residential density has a positive impact on online shopping frequency. Higher accessibility to metro stations has an indirect and negative influence on e-shopping frequency through pro-e-shopping attitudes. In contrast, mediated by e-shopping attitudes, higher accessibility to bus stations has an indirect and positive impact on online shopping frequency. The mediating role of attitudes provides a possible explanation for the influences of transportation accessibility on e-shopping frequency. Land use policies seem influential in online shopping attitudes and frequency, and thus moderate e-shoppers’ travel demand
Does a residential relocation enable satisfying travel?
Transport-related residential self-selection indicates that people try to live in a neighbourhood in line with their travel preferences and needs. Although studies have found that travel attitudes are mostly aligned with urban form characteristics of the residential location, no studies have explored whether people are actually able to travel in their preferred way after having relocated. In this study we analyse whether individuals’ travel patterns are consistent with their travel preferences following residential relocation and if this congruency affects their travel satisfaction. Results from 1650 recently relocated residents in the city of Ghent (Belgium) indicate that most respondents were able to change their travel behaviour in congruence with their travel attitudes. The study found that a decrease in travel duration, distance, car use, and public transport use, and an increase in walking and cycling increased travel satisfaction. This is particularly true when changes in travel behaviour interacted with travel attitudes. Results show that when walking and cycling levels change in line with travel attitudes, travel satisfaction increases strongly. However, the interaction between travel behaviour changes and travel attitudes does not always explain travel satisfaction (improvements). We found, for instance, that individuals with reduced travel durations, despite having a positive attitude towards travel in general, have high levels of travel satisfaction (improvements). The findings indicate that built environment interventions enabling a transport-related self-selection process have the potential to contribute to satisfying travel and thereby to improve subjective well-being of residents
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