1,682 research outputs found
Extracting information from short messages
Much currently transmitted information takes the form of e-mails or SMS text messages and so extracting information from such short messages is increasingly important. The words in a message can be partitioned into the syntactic structure, terms from the domain of discourse and the data being transmitted. This paper describes a light-weight Information Extraction component which uses pattern matching to separate the three aspects: the structure is supplied as a template; domain terms are the metadata of a data source (or their synonyms), and data is extracted as those words matching placeholders in the templates
Importance of termites in the diet of the aardwolf Proteles cristatus in South Africa
Analysis of 81 faecal samples collected from seven different localities in South Africa revealed that termites are the most important food item in the diet of the aardwolf. Trinervitermes was found to be the most important genus of termite in the faeces from six of the seven localities, whilst other genera of termites, ants, other insects and millipedes mostly occurred as traces in the faeces. No vertebrate remains or traces of carrion were found.Analise van 81 mismonsters uitsewe verskillende omgewings in Suid-Afrika versamel het getoon dat termiete die belangrikste kositem in die dieè€t van die aardwolf is. Trinervitermes is die belangrikste termietgenus in die mismonsters uit ses van die sewe omgewings, terwyl slegs spore van ander termietgenera, miere, ander insekte en duisendpote in die mis waargeneem is. Geen werweldier- oorblyfsels of aas is gevind nie
Rheology at the micro-scale: new tools for bio-analysis
We present a simple and non-invasive experimental procedure to measure the linear viscoelastic properties of cells by passive particle tracking microrheology. In order to do this, a generalised Langevin equation is adopted to relate the timedependent thermal fluctuations of a probe sensor, immobilised to the cellâs membrane, to the frequency-dependent viscoelastic moduli of the cell. The method has been validated by measuring the linear viscoelastic response of a soft solid and then applied to cell physiology studies. It is shown that the viscoelastic moduli are related to the cellâs cytoskeletal structure, which in this work is modulated either by inhibiting the actin/myosin-II interactions by means of blebbistatin or by varying the solution osmolarity from iso- to hypo-osmotic conditions. The insights gained from this form of rheological analysis promises to be a valuable addition to physiological studies; e.g. cell physiology during pathology and pharmacological response
Developing an ancient epithelial appendage: FGF signalling regulates early tail denticle formation in sharks
Background: Vertebrate epithelial appendages constitute a diverse group of organs that includes integumentary
structures such as reptilian scales, avian feathers and mammalian hair. Recent studies have provided new evidence for
the homology of integumentary organ development throughout amniotes, despite their disparate fnal morphologies.
These structures develop from conserved molecular signalling centres, known as epithelial placodes. It is not yet
certain whether this homology extends beyond the integumentary organs of amniotes, as there is a lack of knowledge
regarding their development in basal vertebrates. As the ancient sister lineage of bony vertebrates, extant chondrichthyans
are well suited to testing the phylogenetic depth of this homology. Elasmobranchs (sharks, skates and
rays) possess hard, mineralised epithelial appendages called odontodes, which include teeth and dermal denticles
(placoid scales). Odontodes constitute some of the oldest known vertebrate integumentary appendages, predating
the origin of gnathostomes. Here, we used an emerging model shark (Scyliorhinus canicula) to test the hypothesis that
denticles are homologous to other placode-derived amniote integumentary organs. To examine the conservation
of putative gene regulatory network (GRN) member function, we undertook small molecule inhibition of fbroblast
growth factor (FGF) signalling during caudal denticle formation.
Results: We show that during early caudal denticle morphogenesis, the shark expresses homologues of conserved
developmental gene families, known to comprise a core GRN for early placode morphogenesis in amniotes. This
includes conserved expression of FGFs, sonic hedgehog (shh) and bone morphogenetic protein 4 (bmp4). Additionally,
we reveal that denticle placodes possess columnar epithelial cells with a reduced rate of proliferation, a conserved
characteristic of amniote skin appendage development. Small molecule inhibition of FGF signalling revealed
placode development is FGF dependent, and inhibiting FGF activity resulted in downregulation of shh and bmp4
expression, consistent with the expectation from comparison to the amniote integumentary appendage GRN.
Conclusion: Overall, these fndings suggest the core GRN for building vertebrate integumentary epithelial appendages
has been highly conserved over 450 million years. This provides evidence for the continuous, historical homology
of epithelial appendage placodes throughout jawed vertebrates, from sharks to mammals. Epithelial placodes
constitute the shared foundation upon which diverse vertebrate integumentary organs have evolved
The construction of a bedrock geology model for the UK: UK3D_v2015
This report is available for download on the BGS UK3D web page to allow the reader to better understand the context and development of UK3D, a national network, or âfence diagram modelâ, of bedrock geology cross-sections. It also explains the development of the metadata underpinning the model and therefore supports use and understanding of UK3D.
The pre-existing BGS GB3D model provided the only nationally consistent representation of the bedrock geology of Great Britain to depths of at least 1 km. The latest version of this model was released in 2014 as the GB3D_v2014 and accompanying report (Mathers et al. 2014b).
However, the existing GB3D_v2014 model lacked equivalent scale presentation of a fence diagram model for Northern Ireland. It was recognised that in order to provide comparable geological information across the United Kingdom it was necessary to upgrade the model to a UK3D fence diagram model incorporating Northern Ireland, with rigorous peer review performed to enable an enhanced dataset.
The objective of this study was therefore to further develop the GB3D model, outlined by Mathers et al. (2014a and b), into a UK3D model by the incorporation of 36 deep boreholes and a framework of 15 cross-sections for Northern Ireland.
The appropriate applications for the revised model are for geoscience communication and education to illustrate the national and regional bedrock geology of the United Kingdom to a depth of at least 1 km with an intended resolution of use in the 1:250 000 to 1:1 million scale range. Limitations inherent in the model preclude such applications as detailed geological assessments, resource-reserve estimation and exploration, and any representation or use outside the intended resolution range.
The new model produced by this study UK3D_v2015 supersedes the earlier 2014 version for England and Wales, for which areas of the fence diagrams remain the same. The Scottish portion of the model remains unchanged from the earlier 2012 version. The new dataset is a wholly owned BGS product and as with its forerunners it is freely available from the BGS website http://bgs.ac.uk as downloads in a variety of formats
The Transition to a Giant Vortex Phase in a Fast Rotating Bose-Einstein Condensate
We study the Gross-Pitaevskii (GP) energy functional for a fast rotating
Bose-Einstein condensate on the unit disc in two dimensions. Writing the
coupling parameter as 1 / \eps^2 we consider the asymptotic regime \eps
\to 0 with the angular velocity proportional to
(\eps^2|\log\eps|)^{-1} . We prove that if \Omega = \Omega_0
(\eps^2|\log\eps|)^{-1} and then a minimizer of
the GP energy functional has no zeros in an annulus at the boundary of the disc
that contains the bulk of the mass. The vorticity resides in a complementary
`hole' around the center where the density is vanishingly small. Moreover, we
prove a lower bound to the ground state energy that matches, up to small
errors, the upper bound obtained from an optimal giant vortex trial function,
and also that the winding number of a GP minimizer around the disc is in accord
with the phase of this trial function.Comment: 52 pages, PDFLaTex. Minor corrections, sign convention modified. To
be published in Commun. Math. Phy
A gamma- and X-ray detector for cryogenic, high magnetic field applications
As part of an experiment to measure the spectrum of photons emitted in
beta-decay of the free neutron, we developed and operated a detector consisting
of 12 bismuth germanate (BGO) crystals coupled to avalanche photodiodes (APDs).
The detector was operated near liquid nitrogen temperature in the bore of a
superconducting magnet and registered photons with energies from 5 keV to 1000
keV. To enlarge the detection range, we also directly detected soft X-rays with
energies between 0.2 keV and 20 keV with three large area APDs. The
construction and operation of the detector is presented, as well as information
on operation of APDs at cryogenic temperatures
Compounded perturbations in coastal areas: contrasting responses to nutrient enrichment and the regime of storm-related disturbance depend on life-history traits
1. Natural systems are exposed to compounded perturbations, whose changes in temporal
variance can be as important as those in mean intensity for shaping the structure of assemblages.
Specifically, climate-related physical disturbances and nutrient inputs due to natural
and/or anthropogenic activities occur concomitantly, but experimental tests of the simultaneous
effects of changes in the regime of more than one perturbation are generally lacking.
Filling this gap is the key to understand ecological responses of natural assemblages to
climate-related change in the intensity and temporal patterning of physical disturbance combined
with other global stressors.
2. Responses to factorial manipulations of nutrient enrichment, mean intensity and temporal
variability in storm-like mechanical disturbance were examined, using benthic assemblages of
tide-pools as model system.
3. Response variables were mean abundance values and temporal variances of taxa with different
life-traits. Consistent negative effects of disturbance intensity were observed for the mean
cover of long-living taxa (algal canopies and the polychaete Sabellaria alveolata), whose temporal
fluctuations were also reduced by more severe mechanical stress. More resilient taxa
(ephemeral algae, mostly green of the genus Ulva) increased under enriched conditions, particularly
when low-intensity events were irregularly applied over time. Opposite effects of disturbance
intensity depending on nutrient availability occurred on filamentous algae (e.g. red of
the genus Ceramium). This was probably due to the fact that, although nutrient enrichment
stimulated the abundance of both algal groups, when this condition was combined with relatively
mild physical disturbance the competitively superior ephemeral green algae tended to
become dominant over filamentous red algae. The same did not occur under high intensity of
disturbance since it likely damaged large, foliose fronds of Ulva-like forms more than small, filamentous
fronds of Ceramium-like forms. Grazers were positively affected by nutrients, likely
responding indirectly to more food available.
4. A direct relationship between the mean abundance of most organisms and their temporal
fluctuations was documented. However, all organisms persisted throughout the study, even
under experimental conditions associated to the largest temporal variation in their abundance,
likely due to their ability to resist to/quickly recover from, the applied perturbations. Therefore,
in systems with great recovery abilities of dominant organisms (e.g. rocky intertidal,
grasslands), effects of traits of the regime of disturbance and nutrient enrichment may modulate the fluctuations of populations not through the elimination and substitution of species,
but through changes in relative abundances of the same species. This contrasts with the
theory that temporal variation in abundance would be directly related to the risk of local
extinction. Present findings enable more accurate predictions of the consequences of climatic
and non-climatic scenarios on the biodiversity of marine and terrestrial systems sharing analogous
functional traits of organisms. Future more intense physical disturbances are expected to
exert negative effects on slow-growing/recovering species (e.g. habitat-formers) irrespectively of
the temporal patterning of the same disturbances and nutrient inputs. On the contrary, more
resistant species (e.g. encrusting algae on rocky shores or below-ground vegetation in grasslands)
are expected to benefit from intense physical disturbance. Species whose abundance is
more directly related to the availability of nutrients (e.g. filamentous and ephemeral algae or
herbs) are expected to generally increase under enriched conditions, but their ability to eventually
become dominant would depend on their ability to grow fast and attain cover large
enough to overwhelm any possible control of concomitant disturbance intensity on their abundance.
If, such as in the present examined system, virtually all organisms can persist, over the
temporal scale of the experiment, under any combination of physical disturbance and nutrient
availability, the resulting overall diversity is not predicted to change drastically. Nevertheless,
low-intensity events evenly distributed and high-intensity events irregularly distributed appear
as the conditions supporting the highest richness of taxa, independently of the availability of
nutrients
Continuing professional development:introducing the ERS International Certificate in Respiratory Sleep Medicine
Certification of specialists in respiratory sleep medicine for the purposes of continuing professional developmen
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