22,391 research outputs found
Robust Recovery of Subspace Structures by Low-Rank Representation
In this work we address the subspace recovery problem. Given a set of data
samples (vectors) approximately drawn from a union of multiple subspaces, our
goal is to segment the samples into their respective subspaces and correct the
possible errors as well. To this end, we propose a novel method termed Low-Rank
Representation (LRR), which seeks the lowest-rank representation among all the
candidates that can represent the data samples as linear combinations of the
bases in a given dictionary. It is shown that LRR well solves the subspace
recovery problem: when the data is clean, we prove that LRR exactly captures
the true subspace structures; for the data contaminated by outliers, we prove
that under certain conditions LRR can exactly recover the row space of the
original data and detect the outlier as well; for the data corrupted by
arbitrary errors, LRR can also approximately recover the row space with
theoretical guarantees. Since the subspace membership is provably determined by
the row space, these further imply that LRR can perform robust subspace
segmentation and error correction, in an efficient way.Comment: IEEE Trans. Pattern Analysis and Machine Intelligenc
Schwarzschild-de Sitter Metric and Inertial Beltrami Coordinates
Under consideration of coordinate conditions, we get the
Schwarzschild-Beltrami-de Sitter (S-BdS) metric solution of the Einstein field
equations with a cosmological constant . A brief review to the de
Sitter invariant special relativity (dS-SR), and de Sitter general relativity
(dS-GR, or GR with a ) is presented. The Beltrami metric
provides inertial reference frame for the dS-spacetime. By examining the
Schwarzschild-de Sitter (S-dS) metric existed in literatures
since 1918, we find that the existed S-dS metric describes
some mixing effects of gravity and inertial-force, instead of a pure gravity
effect arisen from "solar mass" in dS-GR. In this paper, we solve the
vacuum Einstein equation of dS-GR, with the requirement of gravity-free metric
. In this way we find S-BdS
solution of dS-GR, written in inertial Beltrami coordinates. This is a new form
of S-dS metric. Its physical meaning and possible applications are discussed.Comment: 16 pages, 1 figur
High Resolution Detection of Synchronously Determining Tilt Angle and Displacement of Test Plane by Blu-Ray Pickup Head
AbstractWe present an optical design for Blu-ray pickup head that can synchronously detect a linear displacement and two-dimensional (2D) angular tilt of the test plane. In order to enhance the accuracy of tilt angle and discriminate more tilted orientations, a high resolution detector (177×177 pixels) is used as the photo detector of the Blu-ray pickup head. The horizontal beam expander is used to make the laser beam be more uniform to improve the accuracy of signal at the photo detector. The signal at the high resolution detector of the pickup head used astigmatic detection is comprised of two displacement signals and one angular signal. The displacement of the test plane is ascertained from the rate of change in the length of semi-major and semi-minor axis for elliptical beam shape on the high resolution detector. The tilt of the test plane is obtained from the brightest position of beam shape. It is not only able to judge the tilt angle for four orientations (α, β, 45°and 135°), but also the tilt angle for four orientations (30°, 60°, 120°and 150°). The smaller pixel size will help to improve the accuracy in the 2D angle measurement further
Stable Agrobacterium-mediated transformation of the halophytic Leymus chinensis (Trin.)
In this study, an efficient procedure for stable Agrobacterium-mediated transformation of Leymus chinensis (Trin.) was established. Agrobacterium tumefaciens strain EHA105, harboring a binary vector pCAMBIA2300, was used for transformation, along with a sweet potato 2-cysteine peroxiredoxin (2-Cys Prx) gene under the control of the stress-inducible sweet potato anionic peroxidase 2 (SWPA2) promoter and the neomycin phosphotransferase (nptII) gene under the control of the cauliflower mosaic virus (CaMV) 35 S promoter. We found that a one-month-old callus derived from mature seeds could be efficiently transformed. Seven-day preculture followed by inoculation with the addition of 100 μmolL-1 acetosyringone (AS) and then a 3 day co-cultivation were performed before selection. Selection of transgenic shoots was done in the presence of 150 mgL-1 kanamycin (KM). An optical density at a wavelength of 600 nm (OD600) of approximately 0.4 for A. tumefaciens infection solution and 20 min of infection time gave the highest transformation efficiency. Polymerase chain reaction (PCR) analysis of KM-resistant plants and newly regenerated rhizomes revealed stable transformation of the 2-Cys Prx gene and the nptII gene, with the highest transformation frequency of 4.93%. RT-RCR analysis was conducted using salt stressed transgenic plants, and the results suggested that 2-Cys Prx had low transcription levels under non-stressed conditions, and increased transcription after 6 h of 200 mM NaCl stress. This gene continued to demonstrate high levels of transcription until 6 h after withdrawal of stress, with a slow recovery. The method reported herein provides a direct opportunity for improvement of the quality traits of L. chinensis via genetic transformation.Keywords: Leymus chinensis, Agrobacterium-mediated transformation, 2-Cys peroxiredoxin, gene transformatio
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