Structure of the Draco Dwarf Spheroidal Galaxy

This article studies the structure of the Draco dwarf spheroidal galaxy with an emphasis on the question of whether the spatial distribution of its stars has been affected by the tidal interaction with the Milky Way, using R- and V-band CCD photometry for eleven fields. The article reports coordinates for the center, a position angle of the major axis, and the ellipticity. It also reports the results of searches for asymmetries in the structure of Draco. These results, and searches for a ``break'' in the radial profile and for the presence of principal sequences of Draco in a color-magnitude diagram for regions more than 50 arcmin from the center, yield no evidence that tidal forces from the Milky Way have affected the structure of Draco.Comment: 25 pages, 11 figures, 3 tables. Accepted for publication in A

Non-equilibrium hysteresis and spin relaxation in the mixed-anisotropy dipolar coupled spin-glass LiHo0.5_{0.5}Er0.5_{0.5}F4_{4}

We present a study of the model spin-glass LiHo$_{0.5}$Er$_{0.5}$F$_4$ using simultaneous AC susceptibility, magnetization and magnetocaloric effect measurements along with small angle neutron scattering (SANS) at sub-Kelvin temperatures. All measured bulk quantities reveal hysteretic behavior when the field is applied along the crystallographic c axis. Furthermore avalanche-like relaxation is observed in a static field after ramping from the zero-field-cooled state up to $200 - 300$ Oe. SANS measurements are employed to track the microscopic spin reconfiguration throughout both the hysteresis loop and the related relaxation. Comparing the SANS data to inhomogeneous mean-field calculations performed on a box of one million unit cells provides a real-space picture of the spin configuration. We discover that the avalanche is being driven by released Zeeman energy, which heats the sample and creates positive feedback, continuing the avalanche. The combination of SANS and mean-field simulations reveal that the conventional distribution of cluster sizes is replaced by one with a depletion of intermediate cluster sizes for much of the hysteresis loop.Comment: 6 pages, 4 figure

Determining orbits for the Milky Way's dwarfs

We calculate orbits for the Milky Way dwarf galaxies with proper motions, and compare these to subhalo orbits in a high resolution cosmological simulation. We use this same simulation to assess how well are able to recover orbits in the face of measurement errors, a time varying triaxial gravitational potential, and satellite-satellite interactions. We find that, for present measurement uncertainties, we are able to recover the apocentre r_a and pericentre r_p to ~ 40%. However, even with better data the non-sphericity of the potential and satellite interactions during group infall make the orbital recovery more challenging. Dynamical friction, satellite mass loss and the mass evolution of the main halo play a more minor role. We apply our technique to nine Milky Way dwarfs with observed proper motions. We show that their mean apocentre is consistent with the most massive subhalos that form before z=10, lending support to the idea that the Milky Way dwarfs formed before reionisation.Comment: 2 pages, 1 figure, conference proceeding in "Hunting for the Dark: The Hidden Side of Galaxy Formation", Malta, 19-23 Oct. 2009, eds. V.P. Debattista & C.C. Popesc

Broad host range species in specialised pathogen groups should be treated with suspicion – a case study on Entyloma infecting Ranunculus

Plant pathogenic smut fungi in the broader sense can be divided into the Ustilaginomycetes, which cause classical smut symptoms with masses of blackish spores being produced in a variety of angiosperms, and the Exobasidiomycetes, which are often less conspicuous, as many do not shed large amounts of blackish spores. The leaf-spot causing members of the genus Entyloma (Entylomatales, Exobasidiomycetes) belong to the latter group. Currently, 172 species that all infect eudicots are included in the genus. Vánky (2012) recognised five Entyloma species on species of Ranunculus s.lat. Two have been reported only from Ficaria verna s.lat., while three, E. microsporum, E. ranunculi-repentis, E. verruculosum, have been reported to have a broad host range, encompassing 30, 26, and 5 species of Ranunculus, respectively. This broad host range is in contrast to the generally high host specificity assumed for species of Entyloma, indicating that they may represent complexes of specialised species. The aim of this study was to investigate Entyloma on Ranunculus s.lat. using multigene phylogenies and morphological comparisons. Phylogenetic analyses on the basis of up to four loci (ITS, atp2, ssc1, and map) showed a clustering of Entyloma specimens according to host species. For some of these Entyloma lineages, names not currently in use were available and reinstated. In addition, Entyloma microsporum s.str. is neotypified. Six novel species are described in this study, namely, Entyloma jolantae on Ranunculus oreophilus, E. klenkei on R. marginatus, E. kochmanii on R. lanuginosus, E. piepenbringiae on R. polyanthemos subsp. nemorosus (type host) and R. repens, E. savchenkoi on R. paludosus, and E. thielii on R. montanus. For all species diagnostic bases and morphological characteristics are provided. The results in this study once more highlight the importance of detailed re-investigation of broad host-range pathogens of otherwise specialised plant pathogen groups

Spatial and temporal dynamics of stream chemistry in a forested watershed

Spatial dynamics of solute chemistry and natural abundance isotopes of nitrate (15N and 18O) were examined in seven locations and at the watershed outlet in 2001 and 2002 in a forest watershed in the Adirondack Mountains of New York State, USA. Temporal dynamics were examined during five discharge periods: winter, snowmelt, spring, summer, and fall, based on discharge levels at the watershed outlet. Solute concentrations were variable across space and time with significant (p≤0.05) interaction effects. Year*period was significant for pH, NH4+, NO3-, total N, DOC, and total Al suggesting that inter-annual variability in discharge levels was more important for these solutes than intra-annual variability. Period*sampling point was significant for pH, Mg2+, Ca2+, sum of base cations, Si, and total Al suggesting that the differences in concentration of these solutes among sampling points were moderated by discharge levels. In general, groundwater sources located in upper watershed controlled stream chemistry at higher elevations with highest pH, Ca2+, sum of base cations, Si, and SO42- concentrations, with higher values in summer, and dilution effects during snowmelt. Two low elevation wetlands had a substantial influence over stream chemistry at those locations contributing lowest NO3- and highest DOC. Snowmelt exhibited among the lowest pH, sum of base cations, and SO42-, and highest NO3-, total N, and total Al; snowmelt appeared to dilute groundwater, and flush stored soil-derived solutes. Summer discharge, composed mainly of groundwater, exhibited the lowest flow, among the highest Mg2+, Ca2+, and lowest DON, DOC, and total Al concentrations. Isotopic analysis indicated that NO3-was microbial with primary source in upper watershed soil, from where it was flushed to stream under high discharge-conditions, or drained to groundwater which became its secondary source when discharge was low. Watershed outlet did not exhibit specific solute levels found at source-areas, but represented solute dynamics in the rest of the watershed well

Bayesian exploratory factor analysis

This paper develops and applies a Bayesian approach to Exploratory Factor Analysis that improves on ad hoc classical approaches. Our framework relies on dedicated factor models and simultaneously determines the number of factors, the allocation of each measurement to a unique factor, and the corresponding factor loadings. Classical identification criteria are applied and integrated into our Bayesian procedure to generate models that are stable and clearly interpretable. A Monte Carlo study confirms the validity of the approach. The method is used to produce interpretable low dimensional aggregates from a high dimensional set of psychological measurements. (authors' abstract

Application of new methods of environment analysis and assessment in landscape audits : case studies of urban areas like Czestochowa, Poland

Following the 2000 European Landscape Convention, a new act strengthening landscape protection instruments has been in force since 2015. It sets forth legal aspects of landscape shaping (Dziennik Ustaw 2015, poz. 774) and introduces landscape audits at the province level. A landscape audit consists in identification and characterization of selected landscapes, assessment of their value, selection of so-called priority landscapes and identification of threats for preservation of their value. An audit complies with GIS standards. Analyses use source materials, i.e. digital maps of physical-geographical mesoregions, current topographic maps of digital resources of cartographic databases, latest orthophotomaps and DTMs, maps of potential vegetation, geobotanic regionalization, historic-cultural regionalization and natural landscape types, documentation of historical and cultural values and related complementary resources. A special new methodology (Solon et al. 2014), developed for auditing, was tested in 2015 in an urban area (Myga-Piatek et al. 2015). Landscapes are characterized by determining their analytic (natural and cultural) and synthetic features, with particular focus on the stage of delimitation and identification of landscape units in urban areas. Czestochowa was selected as a case study due to its large natural (karst landscapes of the Czestochowa Upland, numerous forests, nature reserves) and cultural (Saint Mary’s Sanctuary, unique urban architecture) potential. Czestochowa is also a city of former iron ore and mineral resources exploitation, still active industry, dynamic urban sprawl within former farming areas, and dynamically growing tourism. Landscape delimitation and identification distinguished 75 landscape units basing on uniform landscape background (uniform cover and use of the land). Landscape assessment used a new assessment method for anthropogenic transformation of landscape – the indicator describing the correlation between the mean shape index (MSI) and the Shannon diversity index (SHDI) (Pukowiec-Kurda, Sobala 2016). Particular threats and planning suggestions, useful in development of urban areas, were presented for selected priority landscapes

Shapes of Knotted Cyclic Polymers(Knots and soft-matter physics: Topology of polymers and related topics in physics, mathematics and biology)

この論文は国立情報学研究所の電子図書館事業により電子化されました。Momentary configurations of long polymers at thermal equilibrium usually deviate from spherical symmetry and can be better described, on average, by a prolate ellipsoid. The asphericity and nature of asphericity (or prolateness) that describe these momentary ellipsoidal shapes of a polymer are determined by specific expressions involving the three principal moments of inertia calculated for configurations of the polymer. Earlier theoretical studies and numerical simulations have established that as the length of the polymer increases, the average shape for the statistical ensemble of random configurations asymptotically approaches a characteristic universal shape that depends on the solvent quality. It has been established, however, that these universal shapes differ for linear, circular, and branched chains. We investigate here the effect of knotting on the shape of cyclic polymers modeled as random isosegmental polygons. We observe that random polygons forming different knot types reach asymptotic shapes that are distinct from the ensemble average shape. For the same chain length, more complex knots are, on average, more spherical than less complex knots. This paper is a shorter, revised version of the article Ref. [12]. For more details, see Ref. [12]

Core Formation by a Population of Massive Remnants

Core radii of globular clusters in the Large and Small Magellanic Clouds show an increasing trend with age. We propose that this trend is a dynamical effect resulting from the accumulation of massive stars and stellar-mass black holes at the cluster centers. The black holes are remnants of stars with initial masses exceeding 20-25 solar masses; as their orbits decay by dynamical friction, they heat the stellar background and create a core. Using analytical estimates and N-body experiments, we show that the sizes of the cores so produced and their growth rates are consistent with what is observed. We propose that this mechanism is responsible for the formation of cores in all globular clusters and possibly in other systems as well.Comment: 5 page