168 research outputs found
GerManC - Towards a Methodology for Constructing and Annotating Historical Corpora
Our paper focuses on the one hand on the challenges posed by the structural variability, flexibility and ambiguity found in historical corpora and evaluates methods of dealing with them on the other.
We are currently engaged in a project which aims to compile a representative corpus of German for the period 1650-1800. Looking at exemplary data from the first stage of this project (1650-1700), which consists of newspaper texts from this period, we first aim from the perspective of corpus linguistics to identify the problems associated with the morphological, syntactical and graphemic peculiarities that are characteristic of that particular stage. Specific phenomena which significantly complicate automatic tagging, lemmatisation and parsing include, for instance, "abperlende" (Admoni 1980; Demske-Neumann 1990), i.e. complex and often asyndetic syntax; non-syntactic, prosodic, virgulated punctuation (Demske et al. 2004; cf. Stolt 1990), inflectional variability (e.g. Admoni 1990; Besch & Wegera 1987), as well as partly unsystematic and almost experimental allomorphic and allographic (Kettmann, 1992) diversity.
Secondly, we outline a methodology which is intended to facilitate the construction and annotation of such corpora which antedate linguistic standardisation. This is informed by "conventional" and innovative tagging techniques and tools, which are evaluated in terms of utility and accuracy. Finally, we attempt to evaluate the degree to which annotation tools for specialist corpora of this kind can be developed which will substitute for manual or semi-automated annotation
The Absence of Soil-dwelling Microflora will Decrease the Fitness of Arabidopsis thaliana in Presence of Opportunistic Fungus such as Penicillium spp.
To support this claim, A. thaliana strain Col-0, was grown in either autoclaved or non-autoclaved soil and in the presence or absence of Penicillium spp. The Penicillium spp. was utilized into a cultural suspension and sprayed at the base of stems of treatments 1 and 3. The culture suspension proved relatively ineffective for the infection of healthy mature plants. However, the suspension did have a minimal effect on young still-developing plants. Autoclaved treatment had a higher mortality rate on juvenile plants than non-autoclaved treatment when suspension was applied. Illustrating that young vascular plants are more susceptible to fungal infection than mature plants
Mündlichkeit und Schriftlichkeit im schulischen Deutschunterricht in England
The present article deals with the relationship between spoken and written language in teaching German at English schools on the basis of enquiries and interviews with teachers and pupils at a number of schools and colleges and at the University of Manchester. We explain the structure of the curriculum, as determined ultimately by the Ministry for Education and its departments, and consider the motivations for ongoing reforms of the school syllabus. In the last two years of secondary school German is taught for the A-level examinations on the basis of prescribed topics about the life, culture, society and history of the German-speaking countries on the basis of authentic material. However, no systematic attention is paid to the acquisition of elements of grammar or vocabulary, so that knowledge of these can be relatively limited to what is necessary to succeed in the examination. Above all, there is an exclusive concentration on the written language, with the acquisition of competence in listening and speaking also based on texts in formal registers, so that students completing the A-level programmes lack the competence (or even confidence) to cope with the register of informal colloquial speech as used spontaneously by native speakers in everyday communication.</p
Accreted versus In Situ Milky Way Globular Clusters
Here we examine the Milky Way's GC system to estimate the fraction of
accreted versus in situ formed GCs. We first assemble a high quality database
of ages and metallicities for 93 Milky Way GCs from literature deep
colour-magnitude data. The age-metallicity relation for the Milky Way's GCs
reveals two distinct tracks -- one with near constant old age of ~12.8 Gyr and
the other branches to younger ages. We find that the latter young track is
dominated by globular clusters associated with the Sagittarius and Canis Major
dwarf galaxies. Despite being overly simplistic, its age-metallicity relation
can be well represented by a simple closed box model with continuous star
formation. The inferred chemical enrichment history is similar to that of the
Large Magellanic Cloud, but is more enriched, at a given age, compared to the
Small Magellanic Cloud. After excluding Sagittarius and Canis Major GCs,
several young track GCs remain. Their horizontal branch morphologies are often
red and hence classified as Young Halo objects, however they do not tend to
reveal extended horizontal branches (a possible signature of an accreted
remnant nucleus). Retrograde orbit GCs (a key signature of accretion) are
commonly found in the young track. We also examine GCs that lie close to the
Fornax-Leo-Sculptor great circle defined by several satellite galaxies. We find
that several GCs are consistent with the young track and we speculate that they
may have been accreted along with their host dwarf galaxy, whose nucleus may
survive as a GC. Finally, we suggest that 27-47 GCs (about 1/4 of the entire
system), from 6-8 dwarf galaxies, were accreted to build the Milky Way GC
system we seen today.Comment: 13 pages, 9 figures, MNRAS in pres
Heated Disc Stars in the Stellar Halo
Minor accretion events with mass ratio M_sat : M_host ~ 1:10 are common in
the context of LCDM cosmology. We use high-resolution simulations of
Galaxy-analogue systems to show that these mergers can dynamically eject disk
stars into a diffuse light component that resembles a stellar halo both
spatially and kinematically. For a variety of orbital configurations, we find
that ~3-5e8 M_sun of primary stellar disk material is ejected to a distance
larger than 5 kpc above the galactic plane. This ejected contribution is
similar to the mass contributed by the tidal disruption of the satellite galaxy
itself, though it is less extended. If we restrict our analysis to the
approximate solar neighborhood in the disk plane, we find that ~1% of the
initial disk stars in that region would be classified kinematically as halo
stars. Our results suggest that the inner parts of galactic stellar halos
contain ancient disk stars and that these stars may have been liberated in the
very same events that delivered material to the outer stellar halo.Comment: 9 pages, 5 figures; MNRAS accepte
An HST/ACS investigation of the spatial and chemical structure and sub-structure of NGC 891, a Milky Way analogue
We present a structural analysis of NGC891, an edge-on galaxy that has long
been considered to be an analogue of the Milky Way. Using starcounts derived
from deep HST/ACS images, we detect the presence of a thick disk component in
this galaxy with vertical scale height 1.44+/-0.03 kpc and radial scale length
4.8+/-0.1 kpc, only slightly longer than that of the thin disk. A stellar
spheroid with a de Vaucouleurs-like profile is detected from a radial distance
of 0.5 kpc to the edge of the survey at 25 kpc; the structure appears to become
more flattened with distance, reaching q = 0.50 in the outermost halo region
probed. The halo inside of 15 kpc is moderately metal-rich (median [Fe/H] ~
-1.1) and approximately uniform in median metallicity. Beyond that distance a
modest chemical gradient is detected, with the median reaching [Fe/H] ~ -1.3 at
20 kpc. We find evidence for subtle, but very significant, small-scale
variations in the median colour and density over the halo survey area. We argue
that the colour variations are unlikely to be due to internal extinction or
foreground extinction, and reflect instead variations in the stellar
metallicity. Their presence suggests a startling conclusion: that the halo of
this galaxy is composed of a large number of incompletely-mixed
sub-populations, testifying to its origin in a deluge of small accretions.Comment: 21 pages, 16 figures, accepted for publication in MNRA
Tidal disruption of satellite galaxies in a semi-analytic model of galaxy formation
We introduce a new physical recipe into the De Lucia and Blaizot version of the Munich semi-analytic model built upon the Millennium dark matter simulation: the tidal stripping of stellar material from satellite galaxies during mergers. To test the significance of the new physical process we apply a Monte Carlo Markov Chain parameter estimation technique constraining the model with the -band luminosity function, colours and the black hole-bulge mass relation. The differences in parameter correlations, and in the allowed regions in likelihood space, reveal the impact of the new physics on the basic ingredients of the model, such as the star-formation laws, feedback recipes and the black hole growth model. With satellite disruption in place, we get a model likelihood four times higher than in the original model, indicating that the new process seems to be favoured by observations. This is achieved mainly due to a reduction in black hole growth that produces a better agreement between the properties of central black holes and host galaxies. Compared to the best-fit model without disruption, the new model removes the excess of dwarf galaxies in the original recipe with a more modest supernova heating. The new model is now consistent with the three observational data sets used to constrain it, while significantly improving the agreement with observations for the distribution of metals in stars. Moreover, the model now follows the build up of intra-cluster light
Metallicity and kinematical clues to the formation of the Local Group
The kinematics and elemental abundances of resolved stars in the nearby
Universe can be used to infer conditions at high redshift, trace how galaxies
evolve and constrain the nature of dark matter. This approach is complementary
to direct study of systems at high redshift, but I will show that analysis of
individual stars allows one to break degeneracies, such as between star
formation rate and stellar Initial Mass Function, that complicate the analysis
of unresolved, distant galaxies.Comment: 10 pages, 5 figures. Invited review at the Astronomische Gesellschaft
Annual Fall Meeting, `Deciphering the Universe through Spectroscopy',
Potsdam, 21-25 September 200
Hide and seek between Andromeda's halo, disk, and giant stream
Photometry in B, V (down to V ~ 26 mag) is presented for two 23' x 23' fields
of the Andromeda galaxy (M31) that were observed with the blue channel camera
of the Large Binocular Telescope during the Science Demonstration Time. Each
field covers an area of about 5.1kpc x 5.1kpc at the distance of M31 ((m-M)o ~
24.4 mag), sampling, respectively, a northeast region close to the M31 giant
stream (field S2), and an eastern portion of the halo in the direction of the
galaxy minor axis (field H1). The stream field spans a region that includes
Andromeda's disk and the giant stream, and this is reflected in the complexity
of the color magnitude diagram of the field. One corner of the halo field also
includes a portion of the giant stream. Even though these demonstration time
data were obtained under non-optimal observing conditions the B photometry,
acquired in time-series mode, allowed us to identify 274 variable stars (among
which 96 are bona fide and 31 are candidate RR Lyrae stars, 71 are Cepheids,
and 16 are binary systems) by applying the image subtraction technique to
selected portions of the observed fields. Differential flux light curves were
obtained for the vast majority of these variables. Our sample includes mainly
pulsating stars which populate the instability strip from the Classical
Cepheids down to the RR Lyrae stars, thus tracing the different stellar
generations in these regions of M31 down to the horizontal branch of the oldest
(t ~ 10 Gyr) component.Comment: 59 pages, 26 figures, 12 tables, ApJ in pres
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