3,056 research outputs found
Is query translation a distinct task from search?
INTRODUCTION
The University of Sheffield participated in iCLEF 2002 using, as a test-bed, the prototype under
development in the Clarity project. Clarity is an EU funded project aimed at developing a system for
cross-language information retrieval for so-called low density languages, those with few translation
resources. Currently translation between English and Finnish is supported; soon Swedish will be added
and in the near future Latvian and Lithuanian.
Clarity is being developed in a user-centred way with user involvement from the beginning. The design
of the first user interface was based on current best practise, particular attention was paid to empirical
evidence for a specific design choice. Six paper-based interface mock-ups representing important
points in the cross-language search task were generated and presented for user assessment as a part of
an extensive user study. The study (reported in Petrelli et al. 2002) was conducted to understand users
and uses of cross-language information retrieval systems. Many different techniques were applied:
contextual enquiry, interviews, questionnaires, informal evaluation of existing cross-language
technology, and participatory design sessions with the interface mock-ups mentioned above. As a
result, a user class profile was sketched and a long list of user requirements was compiled. As a followup,
a redesign session took place and the new system was designed for users whoknow the language(s) they are searching (polyglots);
• search for writing (journalists, translators business analysts);
• have limited searching skills;
• know the topic in advance or will learn/read on it while searching;
• use many languages in the same search session and often swap between them.
New system features were listed as important and the user interface was redesigned. Considering the
result of the study the new interface allowed the user to dynamically change the language setting from
query to query, hid the query translation and showed the retrieved set as ranked list primary.
Despite the fact that this new design was considered to be more effective, a comparison between the
first layout based on the relevant literature and the new one based on the user study was considered an
important research question. In particular, the choice of hiding the query translation was considered an
important design decision, against the common agreement to allow and support the user in controlling
the system actions. Thus the participation of Sheffield in iCLEF was organized around the idea of
checking if the user should validate the query translation before the search is run or instead if the
system should perform the translation and search in a single step without any user’s supervision
Magnetic anisotropy and spin-spiral wave in V, Cr and Mn atomic chains on Cu(001) surface: First principles calculations
Recent ab intio studies of the magnetic properties of all 3d transition
metal(TM) freestanding atomic chains predicted that these nanowires could have
a giant magnetic anisotropy energy (MAE) and might support a spin-spiral
structure, thereby suggesting that these nanowires would have technological
applicationsin, e.g., high density magnetic data storages. In order to
investigate how the substrates may affect the magnetic properties of the
nanowires, here we systematically study the V, Cr and Mn linear atomic chains
on the Cu(001) surface based on the density functional theory with the
generalized gradient approximation. We find that V, Cr, and Mn linear chains on
the Cu(001) surface still have a stable or metastable ferromagnetic state.
However, the ferromagnetic state is unstable against formation of a
noncollinear spin-spiral structure in the Mn linear chains and also the V
linear chain on the atop sites on the Cu(001) surface, due to the frustrated
magnetic interactions in these systems. Nonetheless, the presence of the
Cu(001) substrate does destabilize the spin-spiral state already present in the
freestanding V linear chain and stabilizes the ferromagnetic state in the V
linear chain on the hollow sites on Cu(001). When spin-orbit coupling (SOC) is
included, the spin magnetic moments remain almost unchanged, due to the
weakness of SOC in 3d TM chains. Furthermore, both the orbital magnetic moments
and MAEs for the V, Cr and Mn are small, in comparison with both the
corresponding freestanding nanowires and also the Fe, Co and Ni linear chains
on the Cu (001) surface.Comment: Accepted for publication in J. Phys. D: Applied Physic
Non-collinear coupling between magnetic adatoms in carbon nanotubes
The long range character of the exchange coupling between localized magnetic
moments indirectly mediated by the conduction electrons of metallic hosts often
plays a significant role in determining the magnetic order of low-dimensional
structures. In addition to this indirect coupling, here we show that the direct
exchange interaction that arises when the moments are not too far apart may
induce a non-collinear magnetic order that cannot be characterized by a
Heisenberg-like interaction between the magnetic moments. We argue that this
effect can be manipulated to control the magnetization alignment of magnetic
dimers adsorbed to the walls of carbon nanotubes.Comment: 13 pages, 5 figures, submitted to PR
On the Geometry of Surface Stress
We present a fully general derivation of the Laplace--Young formula and
discuss the interplay between the intrinsic surface geometry and the extrinsic
one ensuing from the immersion of the surface in the ordinary euclidean
three-dimensional space. We prove that the (reversible) work done in a general
surface deformation can be expressed in terms of the surface stress tensor and
the variation of the intrinsic surface metric
Levitation Using Microwave-Induced Plasmas
The levitation of objects above a microwave horn is demonstrated. High-power microwave pulses generate a low-temperature, diffuse plasma on the surface of the horn window. The thermal effect of the surface plasma brings about a localized increase in the pressure and results in a vertical flow of air, thus levitating the object
Collective synchronization in spatially extended systems of coupled oscillators with random frequencies
We study collective behavior of locally coupled limit-cycle oscillators with
random intrinsic frequencies, spatially extended over -dimensional
hypercubic lattices. Phase synchronization as well as frequency entrainment are
explored analytically in the linear (strong-coupling) regime and numerically in
the nonlinear (weak-coupling) regime. Our analysis shows that the oscillator
phases are always desynchronized up to , which implies the lower critical
dimension for phase synchronization. On the other hand, the
oscillators behave collectively in frequency (phase velocity) even in three
dimensions (), indicating that the lower critical dimension for frequency
entrainment is . Nonlinear effects due to periodic nature of
limit-cycle oscillators are found to become significant in the weak-coupling
regime: So-called {\em runaway oscillators} destroy the synchronized (ordered)
phase and there emerges a fully random (disordered) phase. Critical behavior
near the synchronization transition into the fully random phase is unveiled via
numerical investigation. Collective behavior of globally-coupled oscillators is
also examined and compared with that of locally coupled oscillators.Comment: 18 pages, 18 figure
Dewetting of an ultrathin solid film on a lattice-matched or amorphous substrate
An evolution partial differential equation for the surface of a non-wetting
single-crystal film in an attractive substrate potential is derived and used to
study the dynamics of a pinhole for the varying initial depth of a pinhole and
the strengths of the potential and the surface energy anisotropy. The results
of the simulations demonstrate how the corresponding parameters may lead to
complete or partial dewetting of the film. Anisotropy of the surface energy,
through faceting of the pinhole walls, is found to most drastically affect the
time to film rupture. In particular, the similations support the conjecture
that the strong anisotropy is capable of the complete suppression of dewetting
even when the attractive substrate potential is strong.Comment: Submitted to PR
Spin transport theory in ferromagnet/semiconductor systems with non-collinear magnetization configurations
We present a comprehensive theory of spin transport in a non-degenerate
semiconductor that is in contact with multiple ferromagnetic terminals. The
spin dynamics in the semiconductor is studied during a perturbation of a
general, non-collinear magnetization configuration and a method is shown to
identify the various configurations from current signals. The conventional
Landauer-B\"{u}ttiker description for spin transport across Schottky contacts
is generalized by the use of a non-linearized I-V relation, and it is extended
by taking into account non-coherent transport mechanisms. The theory is used to
analyze a three terminal lateral structure where a significant difference in
the spin accumulation profile is found when comparing the results of this model
with the conventional model.Comment: 17 pages, 10 figure
On Some Classes of mKdV Periodic Solutions
We obtain exact periodic solutions of the positive and negative modified
Kortweg-de Vries (mKdV) equations. We examine the dynamical stability of these
solitary wave lattices through direct numerical simulations. While the positive
mKdV breather lattice solutions are found to be unstable, the two-soliton
lattice solution of the same equation is found to be stable. Similarly, a
negative mKdV lattice solution is found to be stable. We also touch upon the
implications of these results for the KdV equation.Comment: 8 pages, 3 figures, to appear in J. Phys.
Examining trends in the representation of young people and alcohol in Australian newspapers over twenty years (2000-2019)
Background: The news media can reflect and influence public opinion, as well as affect individual practice. In the context of significant changes in alcohol consumption among young people over the past twenty years, we examined Australian newspaper reporting of young people (under 18 years) and alcohol to assess whether there have been changes over time in the content and slant of articles that reflect or elucidate these trends.
Methods: Factiva was used to search newspaper articles from major Australian newspapers over a twenty year period (2000-2019). After screening, two researchers coded 2,415 newspaper articles across four key domains: article type, article theme, sources cited and topic slant (e.g. approving, disapproving tone). Change over time across the study period was assessed using joinpoint Poisson regression analyses.
Results: There was a significant increase in articles on young people and alcohol between 2000 and 2008, before a corresponding decrease to 2019. Policy or prevention strategies were the most common theme of articles (35.8%), followed by articles reporting on risks or harms associated with alcohol use for young people (18.1%). Researchers were the most common source reported (25.1%), followed by politicians (19.0%). Three quarters of articles (75.9%) had a socially disapproving topic slant, which increased significantly up until 2011, with a corresponding decrease thereafter.
Conclusion: Attention to, and problematisation of, young people and alcohol increased in the first decade of this millennium which may have acted to sustain or accelerate declining drinking trends. However, this dissipated back to baseline levels in the second decade, which may indicate a lag time in recognition of young people’s drinking becoming less of a public health ‘problem’
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