101 research outputs found
Maltese bats show phylogeographic affiliation with North-Africa : implications for conservation
In the Mediterranean region, cryptic diversity of bats is common. As distinct genetic lineages should be managed independently for conservation, insight into bat phylogeography is important. The Maltese islands are located in the centre of the Mediterranean between North Africa and Sicily and are densely populated. At present, it is thought that at least seven species of bats are native, but phylogeographic affiliations remain largely unexplored. Therefore, we sequenced a ca. 540 bp fragment of the mitochondrial 16S rRNA gene from 23 bats, which were captured during the citizen-science project Akustika. We found two morphologically cryptic lineages common in North Africa, Plecotus gaisleri and a mainly North-African lineage of Hypsugo savii (named Hypsugo cf. darwinii in some recent studies). We also recorded two Pipistrellus species. The P. kuhlii haplotype belonged to a lineage present in North-Africa and across the Mediterranean. Within P. pipistrellus we found two novel haplotypes that clustered within a North-African clade, well distinguished from the European haplotypes. Our results highlight the historic connection between the bat fauna of the Maltese Islands and North Africa. Malta is one of the few regions in the European Union where P. gaisleri and the North-African clades of P. pipistrellus and H. savii occur. Hence, Malta has an exceptionally high responsibility for the conservation of these taxa in Europe
Constraining the Mass Profiles of Stellar Systems: Schwarzschild Modeling of Discrete Velocity Datasets
(ABRIDGED) We present a new Schwarzschild orbit-superposition code designed
to model discrete datasets composed of velocities of individual kinematic
tracers in a dynamical system. This constitutes an extension of previous
implementations that can only address continuous data in the form of (the
moments of) velocity distributions, thus avoiding potentially important losses
of information due to data binning. Furthermore, the code can handle any
combination of available velocity components, i.e., only line-of-sight
velocities, only proper motions, or a combination of both. It can also handle a
combination of discrete and continuous data. The code finds the distribution
function (DF, a function of the three integrals of motion E, Lz, and I3) that
best reproduces the available kinematic and photometric observations in a given
axisymmetric gravitational potential. The fully numerical approach ensures
considerable freedom on the form of the DF f(E,Lz,I3). This allows a very
general modeling of the orbital structure, thus avoiding restrictive
assumptions about the degree of (an)isotropy of the orbits. We describe the
implementation of the discrete code and present a series of tests of its
performance based on the modeling of simulated datasets generated from a known
DF. We find that the discrete Schwarzschild code recovers the original orbital
structure, M/L ratios, and inclination of the input datasets to satisfactory
accuracy, as quantified by various statistics. The code will be valuable, e.g.,
for modeling stellar motions in Galactic globular clusters, and those of
individual stars, planetary nebulae, or globular clusters in nearby galaxies.
This can shed new light on the total mass distributions of these systems, with
central black holes and dark matter halos being of particular interest.Comment: ApJ, in press; 51 pages, 11 figures; manuscript revised following
comments by refere
First molecular evidence of an invasive agricultural pest, Drosophila suzukii, in the diet of a common bat, Pipistrellus pipistrellus, in Belgian orchards
Bats are major consumers of arthropods, including many agricultural pest species, and can thus reduce and prevent crop damage. However, few, if any, data is available on the potential role of bats in pest control in central Europe. Evidence that bats prey upon locally important pest species would be an important first step to demonstrate their value to local farmers and facilitate conservation measures. In this pilot study, we used a DNA metabarcoding approach to investigate the diet composition of common pipistrelles and brown long-eared bats captured in orchards in Belgium. We show that the spotted wing drosophila (Drosophila suzukii), one of the most harmful pest species in this region, was part of the diet of common pipistrelles. This pest species was recorded in one of the five samples from common pipistrelles. Our results indicate that bats can be valuable assets for biological pest suppression in West-European orchards, thus setting a path for future studies
Everyday pedagogies: New perspectives on youth participation, social learning and citizenship
This chapter focuses on learning from action research projects conducted with young people as part of the PARTISPACE research to explore the implications of young people’s changing forms of participation for innovating pedagogies of participation and citizenship. It aims to offer a new perspective on everyday pedagogies of youth participation understood as processes of situated social learning in action, as young people reflexively engage with and make sense of everyday contexts. The chapter describes by reviewing some critiques of citizenship education, introducing the ideas of Youth Participatory Action Research, and explaining how these were adopted in PARTISPACE. It also focuses on particular aspects of young people’s participation in the projects: the ways in which young people develop agency and capacity through experience; the significance of experimentation, creativity and emergence; reflexive learning and negotiation of boundaries; and relational practices of participatory social learning
Learning on the move: exploring work with vulnerable young men through the lens of movement
This paper discusses a practice context in which process and movement are central to the provision of care and support. It draws on data from a research project conducted with The Men’s Room, Manchester, England which used ethnographic and mobile methods to explore the complex task staff undertake in engaging and supporting highly vulnerable young men. The organisation’s commitment to getting alongside these young men includes a mobile and highly improvised use of temporary city centre spaces for delivering its work. In this paper, I argue that these movements of practice are not simply a logistical necessity or a physical activity, but involve a kinetic way of attending, reflecting, thinking and knowing in which the organisation’s movements are intrinsic to the provision of care and support
Building up the Stellar Halo of the Galaxy
We study numerical simulations of satellite galaxy disruption in a potential
resembling that of the Milky Way. Our goal is to assess whether a merger origin
for the stellar halo would leave observable fossil structure in the phase-space
distribution of nearby stars. We show how mixing of disrupted satellites can be
quantified using a coarse-grained entropy. Although after 10 Gyr few obvious
asymmetries remain in the distribution of particles in configuration space,
strong correlations are still present in velocity space. We give a simple
analytic description of these effects, based on a linearised treatment in
action-angle variables, which shows how the kinematic and density structure of
the debris stream changes with time. By applying this description we find that
a single satellite of current luminosity 10^8 L_\sun disrupted 10 Gyr ago
from an orbit circulating in the inner halo (mean apocentre kpc)
would contribute about kinematically cold streams with internal
velocity dispersions below 5 km/s to the local stellar halo. If the whole
stellar halo were built by disrupted satellites, it should consist locally of
300 - 500 such streams. Clear detection of all these structures would require a
sample of a few thousand stars with 3-D velocities accurate to better than 5
km/s. Even with velocity errors several times worse than this, the expected
clumpiness should be quite evident. We apply our formalism to a group of stars
detected near the North Galactic Pole, and derive an order of magnitude
estimate for the initial properties of the progenitor system.Comment: 28 pages, 10 figures, minor changes, matches the version to appear in
MNRAS, Vol. 307, p.495-517 (August 1999
Stable Models of Elliptical Galaxies
We construct stable axially symmetric models of elliptical galaxies. The
particle density on phase space for these models depends monotonically on the
particle energy and on the third component of the angular momentum. They are
obtained as minimizers of suitably defined energy-Casimir functionals, and this
implies their nonlinear stability. Since our analysis proceeds from a rigorous
but purely mathematical point of view it should be interesting to determine if
any of our models match observational data in astrophysics. The main purpose of
these notes is to initiate some exchange of information between the
astrophysics and the mathematics communities.Comment: 26 page
Regimes of youth participation? Comparative analysis of youth policies and participation across European cities
This paper problematizes the assumption that national policies have a direct impact on youth participation at local level and analyses the relationships between local forms of youth participation and local and national policies. Relying on data from a EU project, the paper focuses on formally institutionalised settings of youth participation and elaborates local constellations of youth participation in six European cities. These constellations may be referred to as regimes of youth participation as they reflect wider structures of power and knowledge that influence the way in which young people’s practices in public spaces and their claims of being part of society are recognised. However, the analysis reveals that rather deducing it from the model of welfare regimes, such a typology needs to be developed starting from the local level and should consider the ways in which different relationships between local youth policies and national welfare states affect youth participation
Non-formal spaces of socio-cultural accompaniment: Responding to young unaccompanied refugees – reflections from the Partispace project.
Drawing on research in progress in the Partispace project we make a case for the recognition of the importance of non-formal spaces in response to young refugees across three different national contexts: Frankfurt in Germany; Gothenburg in Sweden; and Manchester in the UK. It is argued that recognition of local regulation and national controls of immigration which support climates of hostility makes it important to recognise and affirm the significance of non-formal spaces and ‘small spaces close to home’ which are often developed in the ‘third space’ of civil society and arise from the impulses driven by the solidarity of volunteers. In these contexts it is important that practices of hospitality can develop which symbolically reconstitute refugees as hosts and subjects of a democratic conversation, without which there is no possible administrative solution to the refugee crisis. It is essential that educational spaces such as schools, colleges and universities forge strong bonds with such emergent spaces
Elliptical Galaxy Dynamics
A review of elliptical galaxy dynamics, with a focus on nonintegrable models.
Topics covered include torus construction; modelling axisymmetric galaxies;
triaxiality; collisionless relaxation; and collective instabilities.Comment: 97 Latex pages, 14 Postscript figures, uses aastex. To appear in
Publications of the Astronomical Society of the Pacific, February 199
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