6 research outputs found
Overlap Removal of Dimensionality Reduction Scatterplot Layouts
Dimensionality Reduction (DR) scatterplot layouts have become a ubiquitous
visualization tool for analyzing multidimensional data items with presence in
different areas. Despite its popularity, scatterplots suffer from occlusion,
especially when markers convey information, making it troublesome for users to
estimate items' groups' sizes and, more importantly, potentially obfuscating
critical items for the analysis under execution. Different strategies have been
devised to address this issue, either producing overlap-free layouts, lacking
the powerful capabilities of contemporary DR techniques in uncover interesting
data patterns, or eliminating overlaps as a post-processing strategy. Despite
the good results of post-processing techniques, the best methods typically
expand or distort the scatterplot area, thus reducing markers' size (sometimes)
to unreadable dimensions, defeating the purpose of removing overlaps. This
paper presents a novel post-processing strategy to remove DR layouts' overlaps
that faithfully preserves the original layout's characteristics and markers'
sizes. We show that the proposed strategy surpasses the state-of-the-art in
overlap removal through an extensive comparative evaluation considering
multiple different metrics while it is 2 or 3 orders of magnitude faster for
large datasets.Comment: 11 pages and 9 figure
Riqueza e abundância de herbĂvoros em flores de Vellozia nivea (Velloziaceae) Richness and abundance of herbivores on Vellozia nivea (Velloziaceae) flowers
Vellozia nivea (Velloziaceae) Ă© planta de porte herbáceo que ocorre em solos rochosos, nos campos rupestres da Serra do CipĂł, MG. Suas flores hermafroditas sĂŁo extremamente macias, representando fonte tenra de alimento para os insetos que predam suas tĂ©palas e estruturas reprodutivas. Este trabalho teve como objetivo observar a influĂŞncia da altura e do nĂşmero de flores da planta hospedeira na abundância e riqueza de insetos herbĂvoros. Foram encontradas o total de 21 morfoespĂ©cies de insetos (nove famĂlias e trĂŞs ordens) associadas Ă s flores de V. nivea. A altura e o nĂşmero de flores da planta nĂŁo apresentaram correlações significativas com a riqueza de herbĂvoros por planta (r² = 0,17; P > 0,05). Entretanto, estes dois fatores juntos explicaram 39% da variação observada na abundância dos insetos herbĂvoros por planta (P < 0,05). Portanto, o nĂşmero de flores e a altura das plantas hospedeiras influenciaram apenas a abundância dos herbĂvoros.<br>Vellozia nivea (Velloziaceae) is a herbaceous plant that occurs on rocky soils in the rupestrian fields of the "Serra do CipĂł", Minas Gerais State, Brazil. Its hermaphrodite flowers are extremely soft, representing a source of tender food for the insects that prey on its tepals and reproductive structures. The aim of this study was to observe the effect of the height and number of flowers of the host plant on the abundance and richness of herbivorous insects. We found 21 morphospecies of insects (nine families and three orders) associated to flowers of V. nivea. No significant correlation between the number of flowers and plant height and the variety of herbivorous insects per plant was observed (r² = 0.17, P > 0.05). However, these two factors together explained 39% of the variation of insect abundance (P < 0.05). Thus, only the abundance of herbivorous insects was influenced by the number of flowers and the height of host plant