498 research outputs found
Exchange bias in GeMn nanocolumns: the role of surface oxidation
We report on the exchange biasing of self-assembled ferromagnetic GeMn
nanocolumns by GeMn-oxide caps. The x-ray absorption spectroscopy analysis of
this surface oxide shows a multiplet fine structure that is typical of the Mn2+
valence state in MnO. A magnetization hysteresis shift |HE|~100 Oe and a
coercivity enhancement of about 70 Oe have been obtained upon cooling (300-5 K)
in a magnetic field as low as 0.25 T. This exchange bias is attributed to the
interface coupling between the ferromagnetic nanocolumns and the
antiferromagnetic MnO-like caps. The effect enhancement is achieved by
depositing a MnO layer on the GeMn nanocolumns.Comment: 7 pages, 5 figure
Improved Implementation of Point Location in General Two-Dimensional Subdivisions
We present a major revamp of the point-location data structure for general
two-dimensional subdivisions via randomized incremental construction,
implemented in CGAL, the Computational Geometry Algorithms Library. We can now
guarantee that the constructed directed acyclic graph G is of linear size and
provides logarithmic query time. Via the construction of the Voronoi diagram
for a given point set S of size n, this also enables nearest-neighbor queries
in guaranteed O(log n) time. Another major innovation is the support of general
unbounded subdivisions as well as subdivisions of two-dimensional parametric
surfaces such as spheres, tori, cylinders. The implementation is exact,
complete, and general, i.e., it can also handle non-linear subdivisions. Like
the previous version, the data structure supports modifications of the
subdivision, such as insertions and deletions of edges, after the initial
preprocessing. A major challenge is to retain the expected O(n log n)
preprocessing time while providing the above (deterministic) space and
query-time guarantees. We describe an efficient preprocessing algorithm, which
explicitly verifies the length L of the longest query path in O(n log n) time.
However, instead of using L, our implementation is based on the depth D of G.
Although we prove that the worst case ratio of D and L is Theta(n/log n), we
conjecture, based on our experimental results, that this solution achieves
expected O(n log n) preprocessing time.Comment: 21 page
Load-Balancing for Parallel Delaunay Triangulations
Computing the Delaunay triangulation (DT) of a given point set in
is one of the fundamental operations in computational geometry.
Recently, Funke and Sanders (2017) presented a divide-and-conquer DT algorithm
that merges two partial triangulations by re-triangulating a small subset of
their vertices - the border vertices - and combining the three triangulations
efficiently via parallel hash table lookups. The input point division should
therefore yield roughly equal-sized partitions for good load-balancing and also
result in a small number of border vertices for fast merging. In this paper, we
present a novel divide-step based on partitioning the triangulation of a small
sample of the input points. In experiments on synthetic and real-world data
sets, we achieve nearly perfectly balanced partitions and small border
triangulations. This almost cuts running time in half compared to
non-data-sensitive division schemes on inputs exhibiting an exploitable
underlying structure.Comment: Short version submitted to EuroPar 201
Uso de aspersão em suínos nas baias de espera: implicações no bem-estar.
Projeto/Plano de Ação: 03.08.60800-01
Efeito na qualidade da carne de suínos submetidos a diferentes períodos de aspersão.
Projeto/Plano de Ação: 03.08.60800-01
Quantitative magneto-optical investigation of superconductor/ferromagnet hybrid structures
We present a detailed quantitative magneto-optical imaging study of several
superconductor/ferromagnet hybrid structures, including Nb deposited on top of
thermomagnetically patterned NdFeB, and permalloy/niobium with erasable and
tailored magnetic landscapes imprinted in the permalloy layer. The
magneto-optical imaging data is complemented with and compared to scanning Hall
probe microscopy measurements. Comprehensive protocols have been developed for
calibrating, testing, and converting Faraday rotation data to magnetic field
maps. Applied to the acquired data, they reveal the comparatively weaker
magnetic response of the superconductor from the background of larger fields
and field gradients generated by the magnetic layer.Comment: 21 pages, including 2 pages of supplementary materia
Meat quality of pigs submitted to diferent water spray periods.
Projeto/Plano de Ação: 02.06.01.001
Stress levels of pigs submitted to three water spray periods.
Projeto/Plano de Ação: 02.06.01.001
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