We perform the first global quantum chromodynamics (QCD) analysis of dihadron production for a comprehensive set of data in electron-positron annihilation, semi-inclusive deep-inelastic scattering, ...and proton-proton collisions, from which we extract simultaneously the transversity distributions of the nucleon and π^{+}π^{-} dihadron fragmentation functions. We incorporate in our fits known theoretical constraints on transversity, namely, its small-x asymptotic behavior and the Soffer bound. We furthermore show that lattice-QCD results for the tensor charges can be successfully included in the analysis. This resolves the previously reported incompatibility between the tensor charges extracted from dihadron production data and lattice QCD. We also find agreement with results for the transversity and tensor charges obtained from measurements on single-hadron production. Overall, our work demonstrates for the first time the universal nature of all available information for the transversity distributions and the tensor charges of the nucleon.
•Natural disturbances in the Alps were reduced by land-use until the 19th century.•Growing stock has increased and forest area has expanded since the mid-19th century.•Structure and disturbances of ...post-1880 forests differ from pre-1880 forests.•Natural disturbances are more important than at any time in the past millennium.
Natural disturbances, such as avalanches, snow breakage, insect outbreaks, windthrow or fires shape mountain forests globally. However, in many regions over the past centuries human activities have strongly influenced forest dynamics, especially following natural disturbances, thus limiting our understanding of natural ecological processes, particularly in densely-settled regions. In this contribution we briefly review the current understanding of changes in forest cover, forest structure, and disturbance regimes in the mountain forests across the European Alps over the past millennia. We also quantify changes in forest cover across the entire Alps based on inventory data over the past century. Finally, using the Swiss Alps as an example, we analyze in-depth changes in forest cover and forest structure and their effect on patterns of fire and wind disturbances, based on digital historic maps from 1880, modern forest cover maps, inventory data on current forest structure, topographical data, and spatially explicit data on disturbances. This multifaceted approach presents a long-term and detailed picture of the dynamics of mountain forest ecosystems in the Alps. During pre-industrial times, natural disturbances were reduced by fire suppression and land-use, which included extraction of large amounts of biomass that decreased total forest cover. More recently, forest cover has increased again across the entire Alps (on average +4% per decade over the past 25–115years). Live tree volume (+10% per decade) and dead tree volume (mean +59% per decade) have increased over the last 15–40yearsin all regions for which data were available. In the Swiss Alps secondary forests that established after 1880 constitute approximately 43% of the forest cover. Compared to forests established previously, post-1880 forests are situated primarily on steep slopes (>30°), have lower biomass, a more aggregated forest structure (primarily stem-exclusion stage), and have been more strongly affected by fires, but less affected by wind disturbance in the 20th century. More broadly, an increase in growing stock and expanding forest areas since the mid-19th century have - along with climatic changes - contributed to an increasing frequency and size of disturbances in the Alps. Although many areas remain intensively managed, the extent, structure, and dynamics of the forests of the Alps reflect natural drivers more strongly today than at any time in the past millennium.
Distributed energy systems (DESs) on a local scale constitute a promising niche to leverage renewable energy provision. These DESs (e.g., micro-cogeneration, multi-energy hubs) integrate renewable ...sources, combined heat and power production, various methods of energy conversion and storage, and active demand-side management. Since the broader uptake of such systems is still at an early stage, research about the adoption potentials of DESs in existing neighborhood contexts is scarce. Given their potential to contribute to energy transitions, it is relevant to gain a better understanding of the conditions under which these systems are diffused. Based on a quantitative study, we investigated the perceived responsibilities and the intended technology uptake of DESs among different societal groups in Switzerland, Germany, and Austria. We analyzed a sample of 2104 survey participants who were exposed to ranking tasks and a framing experiment and were asked questions about both opportunities and challenges in implementing DESs. Our results show an openness to engage with DESs; on average, the opportunities in applying DESs are rated higher than the challenges. However, in all three countries, the participants place the responsibility for the energy system transitions on the national government and large energy supply utilities. Municipalities and households are not yet considered relevant innovators. Moreover, the support of DESs is found to be independent from framing the DES implementation in relation to different scales of rationale (global climate change, national energy independence, or local autarky). Our findings illustrate not only the agents’ attitudes toward DESs but also the structural path dependencies involving the implementation of distributed energy technologies. Our study implies the need to address the willingness to invest in new distributed energy infrastructures at the household level in the future. We discuss the necessity of identifying barriers to and drivers of technology applications ex-ante.
•Understoreys are an important functional component of temperate forests.•Global change affects understorey composition via a range of pathways.•We review 14 published understorey models and evaluate ...their comprehensiveness.•None of the existing models fully accounts for all potential effects of global change.•We suggest several ways forward to develop a next generation of understorey models.
The understorey harbours a substantial part of vascular plant diversity in temperate forests and plays an important functional role, affecting ecosystem processes such as nutrient cycling and overstorey regeneration. Global change, however, is putting these understorey communities on trajectories of change, potentially altering and reducing their functioning in the future. Developing mitigation strategies to safeguard the diversity and functioning of temperate forests in the future is challenging and requires improved predictive capacity. Process-based models that predict understorey community composition over time, based on first principles of ecology, have the potential to guide mitigation endeavours but such approaches are rare. Here, we review fourteen understorey modelling approaches that have been proposed during the last three decades. We evaluate their inclusion of mechanisms that are required to predict the impact of global change on understorey communities. We conclude that none of the currently existing models fully accounts for all processes that we deem important based on empirical and experimental evidence. Based on this review, we contend new models are needed to project the complex impacts of global change on forest understoreys. Plant functional traits should be central to such future model developments, as they drive community assembly processes and provide valuable information on the functioning of the understorey. Given the important role of the overstorey, a coupling of understorey models to overstorey models will be essential to predict the impact of global change on understorey composition and structure, and how it will affect the functioning of temperate forests in the future.
We applied a multiscale modeling approach that involves the statistical-mechanical three-dimensional reference interaction site model with the Kovalenko-Hirata closure approximation (3D-RISM-KH ...molecular theory of solvation) as well as density functional theory (DFT) of electronic structure to study the role of water in aggregation of the asphaltene model compound 4,4'-bis(2-pyren-1-yl-ethyl)-2,2'-bipyridine (PBP) X. Tan, H. Fenniri and M. R. Gray, Energy Fuels, 2008, 22, 715. The solvation free energy and potential of mean force predicted by 3D-RISM-KH reveal favorable pathways for disaggregation of PBP dimers in pure versus water-saturated chloroform solvent. The water density distribution functions elucidate hydrogen bonding preferences and water bridge formation between PBP monomers. The ΔG(298) values of -5 to -7 kcal mol(-1) for transfer of water molecules in chloroform to a state interacting with PBP molecules are in agreement with experimental results. Geometry optimization and thermochemistry analysis of PBP dimers with and without water bridges using WB97Xd/6-31G(d,p) predict that both PBP dimerization and dimer stabilization by water bridges are spontaneous (ΔG(298) < 0). The (1)H NMR chemical shifts of PBP monomers and dimers predicted using the gauge-independent atomic orbital method and polarizable continuum model for solvation in chloroform are in an excellent agreement with the experimental results for dilute and concentrated PBP solutions in chloroform, respectively X. Tan, H. Fenniri and M. R. Gray, Energy Fuels, 2009, 23, 3687. The DFT calculations of PBP dimers with explicit water show that bridges containing 1-3 water molecules lead to stabilization of PBP dimers. Additional water molecules form hydrogen bonds with these bridges and de-shield the PBP protons, negating the effect of water on the (1)H(C3) NMR chemical shift of PBP, in agreement with experiment. The ΔG(298) results show that hydrogen bonding to water and water-promoted polynuclear assembly bridging is as important as π-π interactions for asphaltene aggregation.
Context
The contribution of forest understory to the temperate forest carbon sink is not well known, increasing the uncertainty in C cycling feedbacks on global climate as estimated by Earth System ...Models.
Objectives
We aimed at quantifying the effect of woody and non-woody understory vegetation on net ecosystem production (NEP) for a forested area of 158 km
2
in the European Alps.
Methods
We simulated C dynamics for the period 2000–2014, characterized by above-average temperatures, windstorms and a subsequent bark beetle outbreak for the area, using the regional ecosystem model LandscapeDNDC.
Results
In the entire study area, woody and non-woody understory vegetation caused between 16 and 37% higher regional NEP as compared to a bare soil scenario over the 15-year period. The mean annual contribution of the understory to NEP was in the same order of magnitude as the average annual European (EU-25) forest C sink. After wind and bark beetle disturbances, the understory effect was more pronounced, leading to an increase in NEP between 35 and 67% compared to simulations not taking into account these components.
Conclusions
Our findings strongly support the importance of processes related to the understory in the context of the climate change mitigation potential of temperate forest ecosystems. The expected increases in stand replacing disturbances due to climate change call for a better representation of understory vegetation dynamics and its effect on the ecosystem C balance in regional assessments and Earth System Models.
•Complementary perspective highlighting public opinions and their dynamics or stability.•Peoples’ free reported arguments focus on values and responsibility.•Opponents and proponents use different ...arguments.•One third of the sample did not change their argumentation over time.•Discussion on the use of descriptive data for policy-making processes.
Used nuclear fuel must be safely disposed. One solution to this complex challenge are deep geological repositories. Participatory approaches accompany the selection of suitable sites for these repositories in many countries and have been studied by risk perception scholars. However, most research has used quantitative cross-sectional data to explain the relationships among the variables of interest (particularly risks) and to inform nuclear policies. In this paper, we introduce a complementary perspective highlighting two fundamental factors: public opinions and their dynamics or stability. We provide results of a longitudinal survey (2 measurements 1year apart) on plans for a nuclear waste repository in Switzerland. The respondents (N=841) submitted their own arguments with which they would discuss the site selection process. In addition, we surveyed the respondents’ general opinions. We found a focus on values and responsibility. Those in favor of the repository used different arguments than those who opposed it or were undecided on it. Women perceived the repository more negatively (general opinion) but did not use different arguments than men. A comparison over time showed that one third of the sample did not change their argumentation. The use of descriptive data to enhance policy-making processes is discussed.
PDF
