1,493 research outputs found
Anomaly Cancellation in Supergravity with Fayet-Iliopoulos Couplings
We review and clarify the cancellation conditions for gauge anomalies which
occur when N=1, D=4 supergravity is coupled to a Kahler non-linear sigma-model
with gauged isometries and Fayet-Iliopoulos couplings. For a flat sigma-model
target space and vanishing Fayet-Iliopoulos couplings, consistency requires
just the conventional anomaly cancellation conditions. A consistent model with
non-vanishing Fayet-Iliopoulos couplings is unlikely unless the Green-Schwarz
mechanism is used. In this case the U(1) gauge boson becomes massive and the
D-term potential receives corrections. A Green-Schwarz mechanism can remove
both the abelian and certain non-abelian anomalies in models with a gauge
non-invariant Kahler potential.Comment: 27 page
Travelling waves for the Gross-Pitaevskii equation II
The purpose of this paper is to provide a rigorous mathematical proof of the
existence of travelling wave solutions to the Gross-Pitaevskii equation in
dimensions two and three. Our arguments, based on minimization under
constraints, yield a full branch of solutions, and extend earlier results,
where only a part of the branch was built. In dimension three, we also show
that there are no travelling wave solutions of small energy.Comment: Final version accepted for publication in Communications in
Mathematical Physics with a few minor corrections and added remark
Video games are exciting: a European study of videogameâinduced seizures and epilepsy.
Epileptic Disord. 2002 Jun;4(2):121-8.
Video games are exciting: a European study of video game-induced seizures and epilepsy.
Kasteleijn-Nolst Trenité DG, Martins da Silva A, Ricci S, Rubboli G, Tassinari CA, Lopes J, Bettencourt M, Oosting J, Segers JP.
Department of Neurology, Medical Centre Alkmaar, PO Box 501, 1800 AM, The Netherlands. [email protected]
Abstract
BACKGROUND: Video game seizures have been reported in photosensitive and non-photosensitive patients with epilepsy. The game Super Mario World, has led to many cases of first seizures. We examined whether this game was indeed more provocative than other programs and whether playing the game added to this effect.
METHODS: We prospectively investigated 352 patients in four European cities, using a standard protocol including testing of a variety of visual stimuli. We correlated historical data on provocative factors in daily life with electroencephalographic laboratory findings.
RESULTS: The video game, Super Mario World proved more epileptogenic than standard TV programs and as provocative as programs with flashing lights and patterns. Most striking was the fact that video game-viewing and-playing on the 50 and 100 Hz TV was significantly more provocative than viewing the standard program (P < 0.001, P < 0.05 respectively). Playing the video game Mario World on a 50 Hz TV, appeared to be significantly more provocative than playing this game on the 100 Hz TV (P < 0.001). Of 163 patients with a history of TV-, VG- or CG-seizures, 85% of them showed epileptiform discharges in response to photic stimulation, 44% to patterns, 59% to 50 Hz TV and 29% to 100 Hz TV.
CONCLUSIONS: Children and adolescents with a history of video game seizures are, in the vast majority, photosensitive and should be investigated with standardised photic stimulation. Games and programs with bright background or flashing images are specifically provocative. Playing a video game on a 100 Hz TV is less provocative [published with videosequences].
PMID: 12105074 [PubMed - indexed for MEDLINE
Corpo, maturação biolĂłgica e actividade fĂsica: um olhar interactivo em crianças e jovens madeirenses
Cada vez mais a sociedade moderna é olhada através da sua condição
fĂsica, enquanto factor de bem-estar, saĂșde, qualidade de vida e longevidade
dos seus membros.
Os indicadores demogråficos actuais da população madeirense
apontam no sentido de uma considerĂĄvel componente juvenil, adolescente e
jovem. No entanto, a evolução demogråfica prevista, decorrente de um
acentuado decréscimo da natalidade, leva a prever um comportamento diverso
da pirĂąmide de idades, assumindo particular ĂȘnfase as questĂ”es relacionadas
com o estudo e a investigação do corpo, a procura de padrÔes, a descrição
normativa, a interpretação das mudanças e o espaço morfológico externo, que
se vem enquadrar no território de investigação reservado à somatotipologia
Designing difficult office space allocation problem instances with mathematical programming
Office space allocation (OSA) refers to the assignment of room space to a set of entities (people, machines, roles, etc.), with the goal of optimising the space utilisation while satisfying a set of additional constraints. In this paper, a mathematical programming approach is developed to model and generate test instances for this difficult and important combinatorial optimisation problem. Systematic experimentation is then carried out to study the difficulty of the generated test instances when the parameters for adjusting space misuse (overuse and underuse) and constraint violations are subject to variation. The results show that the difficulty of solving OSA problem instances can be greatly affected by the value of these parameters
Viabilidade de uso do hĂbrido Hawaii 7996 como porta-enxerto de cultuvares comerciais de tomate.
A tĂ©cnica de enxertia Ă© utilizada em algumas hortaliças, principalmente em ĂĄreas infestadas, para atribuir resistĂȘncia a patĂłgenos do solo, minimizando as perdas de produção de cultivares suscetĂveis. Este trabalho teve como objetivo avaliar o desenvolvimento e a produtividade de plantas de tomateiro enxertadas em hĂbrido, tido como resistente a Ralstonia solanacearum, em comparação a pĂ©s-francos. O experimento foi desenvolvido em viveiro (produção de mudas e enxertia) e em cĂ©u aberto, no municĂpio de Cruz das Almas, Bahia, no perĂodo de outubro de 2003 a fevereiro de 2004. Utilizou-se o mĂ©todo de enxertia de fenda cheia, com o hĂbrido âHawaii 7996â como porta-enxerto e as cultivares Santa Clara, Santa Cruz Kada e DĂ©bora Plus, suscetĂveis a R. solanacearum, como enxerto. O delineamento experimental foi em blocos ao acaso, com seis tratamentos (3 enxertados e 3 pĂ©s-francos), 5 repetiçÔes e 6 plantas por parcela Ăștil. Avaliaram-se os caracteres: diĂąmetro do caule, altura da planta e da primeira inflorescĂȘncia, distĂąncia entre inflorescĂȘncias e produtividade comercial de frutos. O desenvolvimento das plantas, a produção total e a massa mĂ©dia dos frutos foram semelhantes para os tratamentos enxertados em relação a seus respectivos pĂ©s-francos e nĂŁo houve incompatibilidade entre porta-enxerto e enxerto. A cultivar Santa Cruz Kada foi mais sensĂvel Ă s condiçÔes agroecolĂłgicas do municĂpio de Cruz das Almas, refletindo negativamente na produção e no peso mĂ©dio dos frutos. Observou-se na enxertia com o hĂbrido âHawaii
7996â potencial para viabilizar a produção de tomateiros comerciais suscetĂveis Ă murcha bacteriana, em ĂĄreas infestadas com R. solanacearum
Traveling waves for nonlinear Schr\"odinger equations with nonzero conditions at infinity, II
We prove the existence of nontrivial finite energy traveling waves for a
large class of nonlinear Schr\"odinger equations with nonzero conditions at
infinity (includindg the Gross-Pitaevskii and the so-called "cubic-quintic"
equations) in space dimension . We show that minimization of the
energy at fixed momentum can be used whenever the associated nonlinear
potential is nonnegative and it gives a set of orbitally stable traveling
waves, while minimization of the action at constant kinetic energy can be used
in all cases. We also explore the relationship between the families of
traveling waves obtained by different methods and we prove a sharp nonexistence
result for traveling waves with small energy.Comment: Final version, accepted for publication in the {\it Archive for
Rational Mechanics and Analysis.} The final publication is available at
Springer via http://dx.doi.org/10.1007/s00205-017-1131-
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