628 research outputs found
Roadmap for optical tweezers
Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UAMOptical tweezers are tools made of light that enable contactless pushing, trapping, and manipulation of objects, ranging from atoms to space light sails. Since the pioneering work by Arthur Ashkin in the 1970s, optical tweezers have evolved into sophisticated instruments and have been employed in a broad range of applications in the life sciences, physics, and engineering. These include accurate force and torque measurement at the femtonewton level, microrheology of complex fluids, single micro- and nano-particle spectroscopy, single-cell analysis, and statistical-physics experiments. This roadmap provides insights into current investigations involving optical forces and optical tweezers from their theoretical foundations to designs and setups. It also offers perspectives for applications to a wide range of research fields, from biophysics to space explorationEuropean Commission (Horizon 2020, Project No. 812780
Improving Spatial Codification in Semantic Segmentation
This paper explores novel approaches for improving the spatial codification
for the pooling of local descriptors to solve the semantic segmentation
problem. We propose to partition the image into three regions for each object
to be described: Figure, Border and Ground. This partition aims at minimizing
the influence of the image context on the object description and vice versa by
introducing an intermediate zone around the object contour. Furthermore, we
also propose a richer visual descriptor of the object by applying a Spatial
Pyramid over the Figure region. Two novel Spatial Pyramid configurations are
explored: Cartesian-based and crown-based Spatial Pyramids. We test these
approaches with state-of-the-art techniques and show that they improve the
Figure-Ground based pooling in the Pascal VOC 2011 and 2012 semantic
segmentation challenges.Comment: Paper accepted at the IEEE International Conference on Image
Processing, ICIP 2015. Quebec City, 27-30 September. Project page:
https://imatge.upc.edu/web/publications/improving-spatial-codification-semantic-segmentatio
Effect of long range spatial correlations on the lifetime statistics of an emitter in a two-dimensional disordered lattice
The effect of spatial correlations on the Purcell effect in a bidimensional
dispersion of resonant nanoparticles is analyzed. We perform extensive
calculations on the fluorescence decay rate of a point emitter embedded in a
system of nanoparticles statistically distributed according to a simple 2D
lattice-gas model near the critical point. For short-range correlations (high
temperature thermalization) the Purcell factors present a long-tailed statistic
which evolves towards a bimodal distribution when approaching the critical
point where the spatial correlation length diverges. Our results suggest
long-range correlations as a possible origin of the large fluctuations of
experimental decay rates in disordered metal films.Comment: 6 pages, 5 figure
Ocupació de Pinus Silvestris L., per IPS Acuminatus Gyll. (Col. Scolyt)
S'estudien sis arbres joves total i exclusivament
ocupats per Ips aeuminatus Gyll., talats a la Vall de Roncal (Navarra) l'estiu de 1.979.
Tots els arbres es trobaven en el mateix moment d'atac, essent l'ocupació dels troncs diferent depenent més de l'arbre que de l'escolítid.
El nombre de femelles gairebé triplica el de mascles, fet que no concorda amb la igualtat que es dóna en el moment de la posta. Creiem que és degut a una sortida diferenciada en el temps que fa sortir primer els mascles.
La densitat d'ocupació augmenta amb l'alçada de l'arbre considerat fins un punt en el que pràcticament s'estabilitza al voltant de 0,24 individus per centímetre quadrat
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