2,457 research outputs found
Accurate and linear time pose estimation from points and lines
The final publication is available at link.springer.comThe Perspective-n-Point (PnP) problem seeks to estimate the pose of a calibrated camera from n 3Dto-2D point correspondences. There are situations, though, where PnP solutions are prone to fail because feature point correspondences cannot be reliably estimated (e.g. scenes with repetitive patterns or with low texture). In such
scenarios, one can still exploit alternative geometric entities, such as lines, yielding the so-called Perspective-n-Line (PnL) algorithms. Unfortunately, existing PnL solutions are not as accurate and efficient as their point-based
counterparts. In this paper we propose a novel approach to introduce 3D-to-2D line correspondences into a PnP formulation, allowing to simultaneously process points and lines. For this purpose we introduce an algebraic line error
that can be formulated as linear constraints on the line endpoints, even when these are not directly observable. These constraints can then be naturally integrated within the linear formulations of two state-of-the-art point-based algorithms,
the OPnP and the EPnP, allowing them to indistinctly handle points, lines, or a combination of them. Exhaustive experiments show that the proposed formulation brings remarkable boost in performance compared to only point or
only line based solutions, with a negligible computational overhead compared to the original OPnP and EPnP.Peer ReviewedPostprint (author's final draft
Expression of the genes for guanyl-specific ribonucleases from Bacillus intermedius and Bacillus pumilus is regulated by the two component signal transduction system PhoP-PhoR in B. subtilis
Promoters of the genes for guanyl-specific ribonucleases, secreted by B. intermedius (binase) and B. pumilus (Rnase Bp) in phosphate deficient conditions, contain regions similar to appropriate consensus sequences in promoters of the PHO regulated genes of B. subtilis. A number of genes expressed in response to phosphate starvation in B. subtilis are regulated by the two component signal transduction system PhoP-PhoR. Expression of recombinant genes for binase and RNase Bp in B. subtilis strains with mutations in the regulatory protein genes of the PHO regulon was studied. Their expression is strongly regulated by the regulatory proteins of the B. subtilis PHO regulon. Copyright (C) 1999 Federation of European Microbiological Societies
A Catalogue of Optically Selected Cores
We present a new catalogue of 406 dense cores optically selected by using the
STScI Digitized Sky Survey (DSS). In this catalogue 306 cores have neither an
Embedded YSO (EYSO) nor a Pre-Main-Sequence (PMS) star, 94 cores have EYSOs (1
core has both an EYSO and a PMS star), and 6 cores have PMS star only. Our
sample of dense cores in the catalogue is fairly complete within a category of
northern Lynds class 5, 6 clouds, and southern Hartley et al. (1986)'s class A
clouds, providing a database useful for the systematic study of dense cores.
Most of the cores listed in the catalogue have diameters between
pc with a mean of pc. The sizes ( pc in the mean) of
cores with EYSOs are found to be usually larger than the sizes ( pc
in the mean) of starless cores. The typical mean gas density of the cores is
. Most of the cores are more likely elongated than
spherical (mean aspect ratio: ). The ratio of the number of cores
with EYSOs to the number of starless cores for our sample is about 0.3,
suggesting that the typical lifetime of starless cores is Myr, about
3 times longer than the duration of the Class 0 and Class I phases. This
lifetime is shorter than expected from models of ambipolar diffusion, by
factors of 2-44.Comment: 22 pages, 8 figures, 3 tables, and to appear in ApJS.
Harvard-Smithsonian Center for Astrophysic
Squeezed States of the Generalized Minimum Uncertainty State for the Caldirola-Kanai Hamiltonian
We show that the ground state of the well-known pseudo-stationary states for
the Caldirola-Kanai Hamiltonian is a generalized minimum uncertainty state,
which has the minimum allowed uncertainty , where is a constant depending on the damping
factor and natural frequency. The most general symmetric Gaussian states are
obtained as the one-parameter squeezed states of the pseudo-stationary ground
state. It is further shown that the coherent states of the pseudo-stationary
ground state constitute another class of the generalized minimum uncertainty
states.Comment: RevTex4, 9 pages, no fingure; to be published in Journal of Physics
Displaced Voices: A Journal of Archives, Migration and Cultural Heritage Volume 2, Issue 1 (Summer 2021)
Twentieth Century Histories of Civic Society’s Responses to Crises of Displacement: A Special Issue to mark the 70th Anniversary of Refugee Council
Displaced Voices is a biannual digital magazine produced twice a year by the Living Refugee Archive team at the University of East London. Displaced Voices aims to provide a digital platform for activists, archivists, researchers, practitioners and academics to contribute to issues pertaining to refugee and migration history; refugee and migrant rights; social justice; cultural heritage and archives. We welcome a range of contributions to the magazine including articles of between 1000-2000 words; reports on fieldwork in archival collections; book recommendations and reviews; and more creative pieces including (but not limited too) cartoons; photography; and poetry. We would also welcome news on activities; publication of reports, projects; letters and news from your own networks.
We welcome submissions from all writers whether you are a student, practitioner, activist or established academic. The Displaced Voices online magazine is born out of the collaborative and intersectional work that we have been undertaking through our work with the refugee and migration archives housed at the University of East London. Our work to date has explored the intersections of refugee and migration studies with narrative and life history research linked to oral history methods and archival approaches to the preservation, documentation and accessibility of archival resources recording the refugee experience.
This magazine is a collaborative project between the Living Refugee Archive at the University of East London; the Oral History Society Migration Special Interest Group and the International Association for the Study of Forced Migration Working Group on the History of Forced Migration and Refugees.
Thematically we are looking to engage with articles that explore the intersection of refugee and forced migration studies; history and cultural heritage studies; narrative research; oral history and archival science
Information Theory based on Non-additive Information Content
We generalize the Shannon's information theory in a nonadditive way by
focusing on the source coding theorem. The nonadditive information content we
adopted is consistent with the concept of the form invariance structure of the
nonextensive entropy. Some general properties of the nonadditive information
entropy are studied, in addition, the relation between the nonadditivity
and the codeword length is pointed out.Comment: 9 pages, no figures, RevTex, accepted for publication in Phys. Rev.
E(an error in proof of theorem 1 was corrected, typos corrected
A QCQP Approach to Triangulation
Triangulation of a three-dimensional point from at least two noisy 2-D images
can be formulated as a quadratically constrained quadratic program. We propose
an algorithm to extract candidate solutions to this problem from its
semidefinite programming relaxations. We then describe a sufficient condition
and a polynomial time test for certifying when such a solution is optimal. This
test has no false positives. Experiments indicate that false negatives are
rare, and the algorithm has excellent performance in practice. We explain this
phenomenon in terms of the geometry of the triangulation problem.Comment: 14 pages, to appear in the proceedings of the 12th European
Conference of Computer Vision, Firenze, Italy, 7-13 October 201
Dynamics and manipulation of entanglement in coupled harmonic systems with many degrees of freedom
Published versio
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