1,815 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
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 cell’s 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 cell’s 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
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 ‘fence diagram model’, 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
A Two-Dimensional Model with Chiral Condensates and Cooper Pairs Having QCD-like Phase Structure
We describe how a generalization of the original Gross-Neveu model from U(N)
to O(N) flavor symmetry leads to the appearance of a pairing condensate at high
density, in agreement with the conjectured phenomenon of color
superconductivity in -dimensional QCD. Moreover, the model displays a
rich phase structure which closely resembles the one expected in two-flavor
QCD.Comment: 11 pages, 1 fugure, Presented at TMU-Yale Symposium on Dynamics of
Gauge Fields: An External Activity of APCTP, Tokyo, Japan, 13-15 Dec 199
The freeze-out mechanism and phase-space density in ultrarelativistic heavy-ion collisions
We explore the consequences of a freeze-out criterion for heavy-ion
collisions, based on pion escape probabilities from the hot and dense but
rapidly expanding collision region. The influence of the expansion and the
scattering rate on the escape probability is studied. The temperature
dependence of this scattering rate favors a low freeze-out temperature of ~100
MeV. In general, our results support freeze-out along finite four-volumes
rather than sharp three-dimensional hypersurfaces, with high-pt particles
decoupling earlier from smaller volumes. We compare our approach to the
proposed universal freeze-out criteria using the pion phase-space density and
its mean free path.Comment: 8 pages, 2 figures, although conclusions are unchanged, the paper has
been re-written and the title has been changed for the sake of better
presentatio
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 die荤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
Anisotropic transport in unidirectional lateral superlattice around half-filling of the second Landau level
We have observed marked transport anisotropy in short period (a=92 nm)
unidirectional lateral superlattices around filling factors nu=5/2 and 7/2:
magnetoresistance shows a sharp peak for current along the modulation grating
while a dip appears for current across the grating. By altering the ratio a/l
(with l=sqrt{hbar/eB_perp} the magnetic length) via changing the electron
density n_e, it is shown that the nu=5/2 anisotropic features appear in the
range 6.6 alt a/l alt 7.2 varying their intensities, becoming most conspicuous
at a/l simeq 6.7. The peak/dip broadens with temperature roughly preserving its
height/depth up to 250 mK. Tilt experiments reveal that the structures are
slightly enhanced by an in-plane magnetic field B_| perpendicular to the
grating but are almost completely destroyed by B_| parallel to the grating. The
observations suggest the stabilization of a unidirectional charge-density-wave
or stripe phase by weak external periodic modulation at the second Landau
level.Comment: REVTeX, 5 pages, 3 figures, Some minor revisions, Added notes and
reference
The Layer 0 Inner Silicon Detector of the D0 Experiment
This paper describes the design, fabrication, installation and performance of
the new inner layer called Layer 0 (L0) that was inserted in the existing Run
IIa Silicon Micro-Strip Tracker (SMT) of the D0 experiment at the Fermilab
Tevatron collider. L0 provides tracking information from two layers of sensors,
which are mounted with center lines at a radial distance of 16.1 mm and 17.6 mm
respectively from the beam axis. The sensors and readout electronics are
mounted on a specially designed and fabricated carbon fiber structure that
includes cooling for sensor and readout electronics. The structure has a thin
polyimide circuit bonded to it so that the circuit couples electrically to the
carbon fiber allowing the support structure to be used both for detector
grounding and a low impedance connection between the remotely mounted hybrids
and the sensors.Comment: 28 pages, 9 figure
- …
