600 research outputs found
Humanitarian Demining and Robotics
Mines were used for the first time during the American Civil War in the United States (1861-1865). Anti-tank mines were later ameliorated and laid on the battlefields of the First World War. Mine clearing operations did not pose major problems with those visible and easy-to-detect anti-tank mines. The reason why Anti-personnel mines have been conceived and systematically used on the anti-tank minefields during the Second World War was because such mines prevented the enemy from easy demining of the defense system
A decade of dental education: Faculty of Dentistry
Published on the occasion of the 10th anniversary of the faculty.Incudes bibliographical references.published_or_final_versionConservative dentistry: achievements and perspectives 47Congratulations Wang, Gungwu Wang, Gungwu viiForeword Wei, Stephen H.Y. Wei, Stephen H.Y. ixAcknowledgements Wei, Stephen H.Y. Wei, Stephen H.Y. xiThe Prince Philip Dental Hospital 1Departments and units: a decade of activities and progressStudents' life in the faculty 151Alumni 155Faculty of Dentistry - dental graduates 1985-1992 157The next decade and beyond - some prospects in dentistry 175Brief history of the Faculty of Dentistry 1Administration and governance 4Other services 7Children's dentistry and orthodontics: achievemnets and perspective 13Oral and maxillofacial survey: achievements and perspectives 69Periodontology and public health: achievements and perspectives 95Prosthetic dentistry: achievements and perspectives 113Dental technology unit 125Dental materials science unit: achievements and perspectives 131Oral Biology Unit: achievements and perspectives 139Optimizing adhesion with mineralized dental tissues Gwinnett, A. John Gwinnett, A.John 177Conservative approach to esthetic dentistry Suzuki, M. Mike Suzuki, M. Mike 183The wonderful world of glass ionomer cements Mount, Graham J. Mount, Graham J. 189Biocompatibility of dental materials Smith, Dennis C. Smith, Dennis C. 197Esthetic implant restorations Lewis, Steven Lewis, Steven 203Chemicals in the treatment of periodontal diseases Gjermo, Per Gjermo, Per 21
Slow equivariant lump dynamics on the two sphere
The low-energy, rotationally equivariant dynamics of n CP^1 lumps on S^2 is
studied within the approximation of geodesic motion in the moduli space of
static solutions. The volume and curvature properties of this moduli space are
computed. By lifting the geodesic flow to the completion of an n-fold cover of
the moduli space, a good understanding of nearly singular lump dynamics within
this approximation is obtained.Comment: 12 pages, 3 figure
Gravitating monopoles in SU(3) gauge theory
We consider the Einstein-Yang-Mills-Higgs equations for an SU(3) gauge group
in a spherically symmetric ansatz. Several properties of the gravitating
monopole solutions are obtained an compared with their SU(2) counterpart.Comment: 7 pages, Latex, 3 figure
Power dependent switching of nonlinear trapping by local photonic potentials
We study experimentally and numerically the nonlinear scattering of wave
packets by local multi-site guiding centers embedded in a continuous dielectric
medium, as a function of the input power and angle of incidence. The extent of
trapping into the linear modes of different sites is manipulated as a function
of both the input power and incidence angle, demonstrating power-controlled
switching of nonlinear trapping by local photonic potentials.Comment: Submitted to Optics Letter
Chern-Simons Solitons, Toda Theories and the Chiral Model
The two-dimensional self-dual Chern--Simons equations are equivalent to the
conditions for static, zero-energy solutions of the -dimensional gauged
nonlinear Schr\"odinger equation with Chern--Simons matter-gauge dynamics. In
this paper we classify all finite charge solutions by first
transforming the self-dual Chern--Simons equations into the two-dimensional
chiral model (or harmonic map) equations, and then using the Uhlenbeck--Wood
classification of harmonic maps into the unitary groups. This construction also
leads to a new relationship between the Toda and chiral model
solutions
Collision-Induced Decay of Metastable Baby Skyrmions
Many extensions of the standard model predict heavy metastable particles
which may be modeled as solitons (skyrmions of the Higgs field), relating their
particle number to a winding number. Previous work has shown that the
electroweak interactions admit processes in which these solitons decay,
violating standard model baryon number. We motivate the hypothesis that
baryon-number-violating decay is a generic outcome of collisions between these
heavy particles. We do so by exploring a 2+1 dimensional theory which also
possesses metastable skyrmions. We use relaxation techniques to determine the
size, shape and energy of static solitons in their ground state. These solitons
could decay by quantum mechanical tunneling. Classically, they are metastable:
only a finite excitation energy is required to induce their decay. We attempt
to induce soliton decay in a classical simulation by colliding pairs of
solitons. We analyze the collision of solitons with varying inherent
stabilities and varying incident velocities and orientations. Our results
suggest that winding-number violating decay is a generic outcome of collisions.
All that is required is sufficient (not necessarily very large) incident
velocity; no fine-tuning of initial conditions is required.Comment: 24 pages, 7 figures, latex. Very small changes onl
Magnetothermodynamics of BPS baby skyrmions
The magnetothermodynamics of skyrmion type matter described by the gauged BPS
baby Skyrme model at zero temperature is investigated. We prove that the BPS
property of the model is preserved also for boundary conditions corresponding
to an asymptotically constant magnetic field. The BPS bound and the
corresponding BPS equations saturating the bound are found. Further, we show
that one may introduce pressure in the gauged model by a redefinition of the
superpotential. Interestingly, this is related to non-extremal type solutions
in the so-called fake supersymmetry method. Finally, we compute the equation of
state of magnetized BSP baby skyrmions inserted into an external constant
magnetic field and under external pressure , i.e., , where
is the "volume" (area) occupied by the skyrmions. We show that the BPS baby
skyrmions form a ferromagnetic medium.Comment: Latex, 39 pages, 14 figures. v2: New results and references added,
physical interpretation partly change
Two Skyrmion Dynamics with Omega Mesons
We present our first results of numerical simulations of two skyrmion
dynamics using an -meson stabilized effective Lagrangian. We consider
skyrmion-skyrmion scattering with a fixed initial velocity of , for
various impact parameters and groomings. The physical picture that emerges is
surprisingly rich, while consistent with previous results and general
conservation laws. We find meson radiation, skyrmion scattering out of the
scattering plane, orbiting and capture to bound states.Comment: 19 pages, 22 figure
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