Transversity and Collins functions from SIDIS and e+e- data

A global analysis of the experimental data on azimuthal asymmetries in semi-inclusive deep inelastic scattering (SIDIS), from the HERMES and COMPASS Collaborations, and in e+e- --> h1 h2 X processes, from the BELLE Collaboration, is performed. It results in the extraction of the Collins fragmentation function and, for the first time, of the transversity distribution function for u and d quarks. These turn out to have opposite signs and to be sizably smaller than their positivity bounds. Predictions for the azimuthal asymmetry A_{UT}^{sin(phi_h + phi_S)}, as will soon be measured at JLab and COMPASS operating on a transversely polarized proton target, are then presented.Comment: Revised version to appear in Phys. Rev. D. Few misprints corrected, new figure

The Sivers Function from SIDIS Data

We study the Sivers effect in transverse single spin asymmetries (SSA) for pion and kaon production in Semi-Inclusive Deep Inelastic Scattering (SIDIS) processes. We perform a fit of A^{sin(phi_h-phi_S)}_UT taking into account the recent data from HERMES and COMPASS Collaborations, which allow a new determination of the Sivers distribution functions for quark and anti-quark with u, d and also s flavours. Estimates for forthcoming SIDIS experiments at COMPASS and JLab are given.Comment: 4 pages, 1 figure. To appear in the proceedings of the XVI International Workshop on Deep-Inelastic Scattering and Related Subjects, DIS 2008, London, U.K., 7-11 April 200

Growth rate of small-scale dynamo at low magnetic Prandtl numbers

In this study we discuss two key issues related to a small-scale dynamo instability at low magnetic Prandtl numbers and large magnetic Reynolds numbers, namely: (i) the scaling for the growth rate of small-scale dynamo instability in the vicinity of the dynamo threshold; (ii) the existence of the Golitsyn spectrum of magnetic fluctuations in small-scale dynamos. There are two different asymptotics for the small-scale dynamo growth rate: in the vicinity of the threshold of the excitation of the small-scale dynamo instability, $\lambda \propto \ln({\rm Rm}/ {\rm Rm}^{\rm cr})$, and when the magnetic Reynolds number is much larger than the threshold of the excitation of the small-scale dynamo instability, $\lambda \propto {\rm Rm}^{1/2}$, where ${\rm Rm}^{\rm cr}$ is the small-scale dynamo instability threshold in the magnetic Reynolds number ${\rm Rm}$. We demonstrated that the existence of the Golitsyn spectrum of magnetic fluctuations requires a finite correlation time of the random velocity field. On the other hand, the influence of the Golitsyn spectrum on the small-scale dynamo instability is minor. This is the reason why it is so difficult to observe this spectrum in direct numerical simulations for the small-scale dynamo with low magnetic Prandtl numbers.Comment: 14 pages, 1 figure, revised versio

Wildlife and pollution: 2001-02 Annual Report

The Wildlife and Pollution contract covers a long-term monitoring programme, the Predatory Bird Monitoring Scheme (PBMS), that examines the levels of certain pollutants in selected wildlife species in Britain. The programme was started in the early 1960s, when there were serious concerns over the effects of organochlorine insecticides and organomercury fungicides on various species of birds and mammals. This early work demonstrated the effects of the organochlorines and eventually contributed to the ban on their use in the UK and abroad. The programme has subsequently assessed the success of these bans by measuring whether there has been a decline in the concentrations of organochlorine pesticides in the livers and eggs of predatory and freshwater fish-eating birds. Investigations have also been made into the levels of industrial polychlorinated biphenyls (PCBs), following their identification as pollutants in 1966. Mercury levels, derived from both agricultural and industrial sources, have also been tracked, although mercury concentrations were not measured in birds collected in 2001. In recent years, investigations have been made into the effects of the newest generation of rodenticides on barn owls Tyto alba. Northern gannet Morus bassanus eggs are also collected approximately biennially from two colonies and, when available, from other sites; eggs were last collected in 2000. This programme is now the longest-running of its kind anywhere in the world and the findings stimulate considerable interest internationally, as well as in Britain. Annual reports give an interim summary of results and every three years these annual results are gathered together into a more substantial report in which they are integrated with previous findings. The latest report of this type covers the period up to and including 2000 (Shore et al. 2005). Results are published periodically in the scientific literature. This current report presents the results of analyses carried out on material collected in 2001. It also includes a review of long-term trends in second-generation anticoagulant rodenticide residues in barn owls that occurred during the monitoring period up to and including the year 2001. The Wildlife and Pollution contract was the subject of scientific assessment within JNCC's rolling programme of peer review in autumn 1993 and was further assessed in 1996. As a result of the last two assessments, some monitoring was curtailed. Most notably, common kestrels Falco tinnunculus are no longer monitored for organochlorines. However, from 2001 onwards, kestrels will be monitored for second-generation anticoagulant rodenticides following the results from an individual study, carried out as part of the PBMS activities, which demonstrated that this species may be particularly vulnerable to exposure to these compounds (Shore et al. 2001). Carcasses and eggs of predatory bird species (such as peregrine falcon Falco peregrinus, common buzzard Buteo buteo, long-eared owl Asio otus, little owl Athene noctua, common kingfisher Alcedo atthis, great crested grebe Podiceps cristatus, and great bittern Botaurus stellaris) which do not form the core part of the PBMS, but are sent to the Centre for Ecology & Hydrology (CEH) by volunteers, are not analysed chemically. However, post-mortem examinations are carried out the carcasses, relevant information is recorded and the cause of death is determined (and reported back to the volunteer who submitted the carcass). Samples of the egg contents and body organs for these species, and samples for the species that do form part of the core monitoring, are all archived at -20°C as part of CEH's unique long-term tissue bank, and are often used in specific targeted research studies in subsequent years. Each section within the Wildlife and Pollution contract is summarised below. Each is dependent on the provision of material from amateur naturalists and other interested parties, and it is not always possible to obtain desired material for analysis, especially from remote areas

Wildlife and pollution: 2000-01 Annual Report

The Wildlife and Pollution contract covers a long-term monitoring programme that examines the levels of certain pollutants in selected wildlife species in Britain. The programme was started in the early 1960s, when there were serious concerns over the effects of organochlorine insecticides and organomercury fungicides on various species of birds and mammals. This early work demonstrated the effects of the organochlorines, and eventually contributed to the ban on their use in the UK and abroad. The programme has measured levels of these compounds in predatory and fish-eating birds since then. Investigations have also been made into the levels of industrial polychlorinated biphenyls (PCBs), following their identification as pollutants in 1966. Mercury levels, derived from both agricultural and industrial sources, have also been tracked. In recent years, investigations have been made into the effects of the latest generation of rodenticides on barn owls Tyto alba. Northern gannet Morus bassanus eggs are also collected approximately biennially from two colonies and, when available, from other sites; eggs were collected from one site in 2000. This programme is now the longest-running of its kind anywhere in the world and the findings stimulate considerable interest internationally, as well as in Britain. Annual reports give an interim summary of results. This current report presents the results of analyses carried out on material collected in 2000. Every three years these annual results are gathered together into a more substantial report in which they are integrated with previous findings. The last report of this type covered the period up to and including 1997 (Newton et al. 1998) and is updated here. The present report summarises the long-term trends in all contaminants (except rodenticides, analysed in Shore et al. 2005) that occurred during the monitoring period up to and including the year 2000. Results are published periodically in the scientific literature, and recent key papers are listed in the references to the present report. The Wildlife and Pollution contract was the subject of scientific assessment within JNCC's rolling programme of peer review in autumn 1993 and was further assessed in 1996. As a result of the last two assessments, some monitoring was curtailed. Specifically, common kestrels Falco tinnunculus were no longer monitored for organochlorines, although from 2001 this species will be monitored annually for second-generation anticoagulant rodenticides. The Centre for Ecology & Hydrology (CEH) still collects specimens for studying other contaminants as part of its core research programme. Similarly, other species (peregrine falcon Falco peregrinus, common buzzard Buteo buteo, long-eared owl Asio otus, little owl Athene noctua, common kingfisher Alcedo atthis, great crested grebe Podiceps cristatus, and great bittern Botaurus stellaris) that were received in small numbers in occasional years were also not analysed routinely, although some were analysed in specific one-off studies and tissues from all birds received at CEH in 2000 are archived in deep-freeze for future potential analyses. Each section within the Wildlife and Pollution contract is summarised below. Each is dependent on the provision of material from amateur naturalists and other interested parties, and it is not always possible to obtain desired material for analysis, especially from remote areas

Local Anisotropy of Fluids using Minkowski Tensors

Statistics of the free volume available to individual particles have previously been studied for simple and complex fluids, granular matter, amorphous solids, and structural glasses. Minkowski tensors provide a set of shape measures that are based on strong mathematical theorems and easily computed for polygonal and polyhedral bodies such as free volume cells (Voronoi cells). They characterize the local structure beyond the two-point correlation function and are suitable to define indices $0\leq \beta_\nu^{a,b}\leq 1$ of local anisotropy. Here, we analyze the statistics of Minkowski tensors for configurations of simple liquid models, including the ideal gas (Poisson point process), the hard disks and hard spheres ensemble, and the Lennard-Jones fluid. We show that Minkowski tensors provide a robust characterization of local anisotropy, which ranges from $\beta_\nu^{a,b}\approx 0.3$ for vapor phases to $\beta_\nu^{a,b}\to 1$ for ordered solids. We find that for fluids, local anisotropy decreases monotonously with increasing free volume and randomness of particle positions. Furthermore, the local anisotropy indices $\beta_\nu^{a,b}$ are sensitive to structural transitions in these simple fluids, as has been previously shown in granular systems for the transition from loose to jammed bead packs

Minkowski Tensors of Anisotropic Spatial Structure

This article describes the theoretical foundation of and explicit algorithms for a novel approach to morphology and anisotropy analysis of complex spatial structure using tensor-valued Minkowski functionals, the so-called Minkowski tensors. Minkowski tensors are generalisations of the well-known scalar Minkowski functionals and are explicitly sensitive to anisotropic aspects of morphology, relevant for example for elastic moduli or permeability of microstructured materials. Here we derive explicit linear-time algorithms to compute these tensorial measures for three-dimensional shapes. These apply to representations of any object that can be represented by a triangulation of its bounding surface; their application is illustrated for the polyhedral Voronoi cellular complexes of jammed sphere configurations, and for triangulations of a biopolymer fibre network obtained by confocal microscopy. The article further bridges the substantial notational and conceptual gap between the different but equivalent approaches to scalar or tensorial Minkowski functionals in mathematics and in physics, hence making the mathematical measure theoretic method more readily accessible for future application in the physical sciences

Sivers Effect for Pion and Kaon Production in Semi-Inclusive Deep Inelastic Scattering

We study the Sivers effect in the transverse single spin asymmetries (SSA) for pion and kaon production in semi-inclusive deep inelastic scattering (SIDIS) processes. We perform a fit of A^sin(phi_h-phi_S)_UT which, by including recent high statistics experimental data for pion and kaon production from HERMES and COMPASS Collaborations, allows a new determination of the Sivers distribution functions for quarks and antiquarks with u, d and s flavours. Estimates for forthcoming SIDIS experiments at COMPASS and JLab are given.Comment: 16 pages, 19 figures; v2: no changes in results and conclusions; some sentences rephrased, few paragraphs (and references) added; a new table (table 2) with individual chi^2 per data points added; figures for JLab at 6 GeV removed; matches the version published on Eur. Phys. J.

Psychosocial peer mediation as sustainable method for conflict prevention and management among refugee communities in Germany

Following the arrival of over 1.2 million refugees and asylum seekers since the 2015 European refugee crisis, Germany has faced enormous humanitarian and societal challenges, with direct implications for participatory peace-building efforts at the local community level. A multitude of postmigration stressors and high prevalence of mental health conditions among refugees contribute to the substantial burden of daily conflicts in refugee shelters and communities. Ongoing exposure to a conflict-prone environment, psychological distress and stigmatization among community members can severely impair the quality of life and aggravate existing health-related, socio-economic and integrational challenges. Previous research has demonstrated the feasibility of individual alternative dispute resolution (ADR) and mental health literacy (MHL) interventions in refugee settings. As interpersonal conflict and psychological well-being constitute mutually interdependent phenomena, integrated methodologies combining ADR with MHL may offer unique value to affected vulnerable populations. However, systemic implementation of such mechanisms in refugee shelters has remained largely unexplored. In recognition of this unmet need and as part of the nonprofit organization R3SOLUTE, we have developed a tailored educational curriculum directed at equipping refugees in shelters and their local neighbor citizens with peer mediation-based ADR and MHL skills. In this multidisciplinary bottom-up approach, termed psychosocial peer mediation (PPM), participants learn to effectively manage and prevent conflicts in their own communities. Based on our field experience with implementing PPM in numerous refugee shelters across Germany between 2018 and 2021, we here provide relevant practical insights and discuss best practices, with a focus on addressing existing challenges and opportunities in the field