3,419 research outputs found
Nanometers-thick self-organized Fe stripes: bridging the gap between surfaces and magnetic materials
We have fabricated 5nm-high Fe(110) stripes by self-organized (SO) growth on
a slightly vicinal R(110)/Al2O3(11-20) surface, with R=Mo, W. Remanence,
coercivity and domain patterns were observed at room temperature (RT). This
contrasts with conventional SO epitaxial systems, that are superparamagnetic or
even non-magnetic at RT due to their flatness. Our process should help to
overcome superparamagnetism without compromise on the lateral size if SO
systems are ever to be used in applications
Humanising complex projects through design thinking and its effects
The last decades of research in project studies show us that humans, rather than technologies, software or mathematical models, shape project success. This is simultaneously fascinating and problematic since, while technologies, software or mathematical models are relatively predictable and straightforward, humans are far more complex, with extremely intricate links between motivations and emotions. This consideration is particularly true in complex projects where a plethora of diverse stakeholders have very different emotions and motivations toward the same project. To address this challenge, this essay proposes using design thinking principles, tools, and techniques to "humanise" complex projects. By bringing together stakeholders, including non-market stakeholders such as local communities, with diverse goals and interests and aligning them with a common purpose, design thinking can help to shape, plan, and deliver successful complex projects. While design thinking is commonly discussed in innovation studies, this essay aims to encourage its investigation and discussion in project studies
Atributo diagnóstico do solo: saturação de bases nas propriedades em transição para o sistema agroecológico, Alto ParaÃso, Rondônia.
O municÃpio de Alto ParaÃso apresenta agricultura familiar expressiva. Estes agricultores se associaram em uma Associação que está ligada a uma cooperativa que trabalha com café agroecológico entre outros produtos. O objetivo deste trabalho foi estudar a saturação de bases do solo em Latossolo Vermelho Amarelo nas propriedades rurais de agricultores familiares que fazem parte no municÃpio e o tipo de manejo do solo nas propriedades em transição para a agroecologia. A pesquisa teve como método: trabalho de campo com auxilio de entrevistas e aplicação de formulário de campo modificado da Empresa Brasileira de Pesquisa Agropecuária ? EMBRAPA-RO e análise de dados de solo. Concluiu-se que estas propriedades encontram-se em processo de transição de uma agricultura convencional e migratória para o sistema de uso agroecológico com auxÃlio dos Sistemas Agroflorestais ? SAF , os solos das propriedades em processo de transição para o modelo agroecológico indicaram um percentual de saturação maior que os solos das que empregam práticas convencionais, práticas de uso e manejo foram modificadas tendo em vista a baixa fertilidade do solo no local que mostrou a necessidade de adubação e calagem
Physical properties of the jet from DG Tauri on sub-arcsecond scales with HST/STIS
We derive the physical properties at the base of the jet from DG Tau both
along and across the flow and as a function of velocity. We analysed seven
optical spectra of the DG Tau jet, taken with the Hubble Space Telescope
Imaging Spectrograph. The spectra were obtained by placing a long-slit parallel
to the jet axis and stepping it across the jet width. The resulting
position-velocity diagrams in optical forbidden emission lines allowed access
to plasma conditions via calculation of emission line ratios.
We find at the base of the jet high electron density, 10, and
very low ionisation, , which combine to give a total
density up to 3 10. This analysis confirms previous reports of
variations in plasma parameters along the jet, (i.e. decrease in density by
several orders of magnitude, increase of from 0.05 to a plateau at 0.7
downstream at 2 from the star). Furthermore, a spatial coincidence is
revealed between sharp gradients in the total density and supersonic velocity
jumps. This strongly suggests that the emission is caused by shock excitation.
The position-velocity diagrams indicate the presence of both fast accelerating
gas and slower, less collimated material. We derive the mass outflow rate,
, in the blue-shifted lobe in different velocity channels, that
contribute to a total of 8 4 10 M
yr. We estimate that a symmetric bipolar jet would transport at the low
and intermediate velocities probed by rotation measurements, an angular
momentum flux of 2.9 1.5 10 M yr
AU km s.
The derived properties of the DG Tau jet are demonstrated to be consistent
with magneto-centrifugal theory. However, non-stationary modelling is required
in order to explain all of the features revealed at high resolution.Comment: 16 pages, 18 figure
Secular dynamics of a planar model of the Sun-Jupiter-Saturn-Uranus system; effective stability into the light of Kolmogorov and Nekhoroshev theories
We investigate the long-time stability of the Sun-Jupiter-Saturn-Uranus
system by considering a planar secular model, that can be regarded as a major
refinement of the approach first introduced by Lagrange. Indeed, concerning the
planetary orbital revolutions, we improve the classical circular approximation
by replacing it with a solution that is invariant up to order two in the
masses; therefore, we investigate the stability of the secular system for
rather small values of the eccentricities. First, we explicitly construct a
Kolmogorov normal form, so as to find an invariant KAM torus which approximates
very well the secular orbits. Finally, we adapt the approach that is at basis
of the analytic part of the Nekhoroshev's theorem, so as to show that there is
a neighborhood of that torus for which the estimated stability time is larger
than the lifetime of the Solar System. The size of such a neighborhood,
compared with the uncertainties of the astronomical observations, is about ten
times smaller.Comment: 31 pages, 2 figures. arXiv admin note: text overlap with
arXiv:1010.260
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