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

Bcr is a substrate for Transglutaminase 2 cross-linking activity

<p>Abstract</p> <p>Background</p> <p>Breakpoint cluster region (Bcr) is a multi-domain protein that contains a C-terminal GTPase activating protein (GAP) domain for Rac. Transglutaminase 2 (TG2) regulates Bcr by direct binding to its GAP domain. Since TG2 has transglutaminase activity that has been implicated in the response to extreme stress, we investigated if Bcr can also act as a substrate for TG2.</p> <p>Results</p> <p>We here report that activation of TG2 by calcium caused the formation of covalently cross-linked Bcr. Abr, a protein related to Bcr but lacking its N-terminal oligomerization domain, was not cross-linked by TG2 even though it forms a complex with it. A Bcr mutant missing the first 62 amino acid residues remained monomeric in the presence of activated TG2, showing that this specific domain is necessary for the cross-linking reaction. Calcium influx induced by a calcium ionophore in primary human endothelial cells caused cross-linking of endogenous Bcr, which was inhibited by the TG2 inhibitor cystamine. Treatment of cells with cobalt chloride, a hypoxia-mimetic that causes cellular stress, also generated high molecular weight Bcr complexes. Cross-linked Bcr protein appeared in the TritonX-100-insoluble cell fraction and further accumulated in cells treated with a proteasome inhibitor.</p> <p>Conclusions</p> <p>Bcr thus represents both an interacting partner under non-stressed conditions and a target of transglutaminase activity for TG2 during extreme stress.</p

Vision based interface system for hands free control of an intelligent wheelchair

<p>Abstract</p> <p>Background</p> <p>Due to the shift of the age structure in today's populations, the necessities for developing the devices or technologies to support them have been increasing. Traditionally, the wheelchair, including powered and manual ones, is the most popular and important rehabilitation/assistive device for the disabled and the elderly. However, it is still highly restricted especially for severely disabled. As a solution to this, the Intelligent Wheelchairs (IWs) have received considerable attention as mobility aids. The purpose of this work is to develop the IW interface for providing more convenient and efficient interface to the people the disability in their limbs.</p> <p>Methods</p> <p>This paper proposes an intelligent wheelchair (IW) control system for the people with various disabilities. To facilitate a wide variety of user abilities, the proposed system involves the use of face-inclination and mouth-shape information, where the direction of an IW is determined by the inclination of the user's face, while proceeding and stopping are determined by the shapes of the user's mouth. Our system is composed of electric powered wheelchair, data acquisition board, ultrasonic/infra-red sensors, a PC camera, and vision system. Then the vision system to analyze user's gestures is performed by three stages: detector, recognizer, and converter. In the detector, the facial region of the intended user is first obtained using Adaboost, thereafter the mouth region is detected based on edge information. The extracted features are sent to the recognizer, which recognizes the face inclination and mouth shape using statistical analysis and <it>K</it>-means clustering, respectively. These recognition results are then delivered to the converter to control the wheelchair.</p> <p>Result & conclusion</p> <p>The advantages of the proposed system include 1) accurate recognition of user's intention with minimal user motion and 2) robustness to a cluttered background and the time-varying illumination. To prove these advantages, the proposed system was tested with 34 users in indoor and outdoor environments and the results were compared with those of other systems, then the results showed that the proposed system has superior performance to other systems in terms of speed and accuracy. Therefore, it is proved that proposed system provided a friendly and convenient interface to the severely disabled people.</p

Gamma-irradiation induces matrix metalloproteinase II expression in a p53-dependent manner

Matrix metalloproteinases (MMPs) are a family of proteinases that degrade the basement membrane and have been implicated in promoting tumor metastasis. MMP-2, one member of this family, was recently found to be a p53 target and subject to p53 upregulation. In this study, we examined the correlation between the expression of MMP-2 and the increased expression of p53 after γ-irradiation. Three human p53-positive cell lines that express wild-type p53, including U2-OS (osteosarcoma), RKO (colon carcinoma), MCF-7 (breast carcinoma), one mouse p53 positive cell line and HepG2 (liver carcinoma), and two p53-negative human cell lines, SAOS-2 (osteosarcoma) and RKO-E6 (colon carcinoma), were used in this study. The MMP-2 activity was analyzed by using gelatin zymography. The p53 level was measured by western blot analysis. Our results show that wild-type p53 induced by ionizing radiation caused a subsequent increase of MMP-2 activity in U2-OS and RKO cells but not in MCF-7, HepG2, SAOS-2, or RKO-E6 cells. These results suggest that the γ-radiation–induced expression of MMP-2 is dependent on the cell type and presence of functional p53. Thus, ionizing radiation could activate MMP-2 activity in a subset of human cancer cells and may lead to an increase in their metastatic potential. Mol. Carcinog. 27:252–258, 2000. © 2000 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/35060/1/2_ftp.pd

Shearing and Mixing Performance of Ultrahigh-Molecular-Weight Hydrolyzed Polyacrylamide (HPAM) Solution in a Helixes Static Mixer

Static mixers have been widely used to dilute high viscosity, high-molecular-weight polymer mother liquor for polymer flooding, in which the mixing performance plays a critical role. In this work, a novel mixing configuration, named as Helixes static mixer, was proposed to reduce high viscosity degradation rate of polyacrylamide solution resulting from mechanical shear during mixing process. Computational fluid dynamics simulations along with experiments were performed to investigate the mixing process. Several criteria such as the intensity of segregation, mixing distance, pressure loss, and shear strain rate were used to evaluate the mixing and shear performance of static mixers. Compared to the SMX and Kenics static mixer, a longer mixing distance is needed for the Helixes static mixer to achieve an ideal mixture. A lower shear strain rate along with less viscosity degradation rate is obtained in flow field of Helixes static mixer. The spiral-lead and helical directions of mixing elements were optimized to improve mixing performance. Experimental results are in good agreement with the numerical simulations on the intensity of segregation. The viscosity degradation rate of HPAM solution which flows through Helixes static mixer is lower than that of SMX and Kenics static mixers

Triaqua(2-{[(E)-5-formyl-2-oxidobenzyl­idene]amino}ethanesulfonato)cobalt(II) dihydrate

The title compound, [Co(C10H9NO5S)(H2O)3]·2H2O, is a cobalt–Schiff base complex derived from taurine. There are two complex mol­ecules and four solvent water mol­ecules in the asymmetric unit. The central Co atom is six coordinated by two O atoms and one N atom of the ligand and three O atoms of water mol­ecules, forming a slightly distorted octa­hedral geometry. The crystal structure is stabilized by several O—H⋯O hydrogen bonds

Ordinary kriging approach to predicting long-term particulate matter concentrations in seven major Korean cities

Objectives Cohort studies of associations between air pollution and health have used exposure prediction approaches to estimate individual-level concentrations. A common prediction method used in Korean cohort studies is ordinary kriging. In this study, performance of ordinary kriging models for long-term particulate matter less than or equal to 10 μm in diameter (PM10) concentrations in seven major Korean cities was investigated with a focus on spatial prediction ability. Methods We obtained hourly PM10 data for 2010 at 226 urban-ambient monitoring sites in South Korea and computed annual average PM10 concentrations at each site. Given the annual averages, we developed ordinary kriging prediction models for each of the seven major cities and for the entire country by using an exponential covariance reference model and a maximum likelihood estimation method. For model evaluation, cross-validation was performed and mean square error and R-squared (R2) statistics were computed. Results Mean annual average PM10 concentrations in the seven major cities ranged between 45.5 and 66.0 μg/m3 (standard deviation=2.40 and 9.51 μg/m3, respectively). Cross-validated R2 values in Seoul and Busan were 0.31 and 0.23, respectively, whereas the other five cities had R2 values of zero. The national model produced a higher crossvalidated R2 (0.36) than those for the city-specific models. Conclusions In general, the ordinary kriging models performed poorly for the seven major cities and the entire country of South Korea, but the model performance was better in the national model. To improve model performance, future studies should examine different prediction approaches that incorporate PM10 source characteristics

AU-Rich Long 3′ Untranslated Region Regulates Gene Expression in Bacteria

3′ untranslated regions (3′ UTRs) and particularly long 3′ UTRs have been shown to act as a new class of post-transcriptional regulatory element. We previously reported that hmsT mRNA stability is negatively regulated by the 3′ UTR of hmsT in Yersinia pestis. To investigate more general effects of 3′ UTRs in Y. pestis, we selected 15 genes potentially possessing long 3′ UTRs with different AU content and constructed their 3′ UTR deletion mutants. Deletion of AU-rich 3′ UTRs increased mRNA levels, whereas deletion of 3′ UTRs with normal AU content resulted in slight or no changes in the mRNA level. In addition, we found that PNPase was important for 3′ UTR-mediated mRNA decay when the transcriptional terminator was Rho-dependent. Finally, we showed that ribosomes promote mRNA stability when bound to a 3′ UTR. Our findings suggest that functional 3′ UTRs might be broadly distributed in bacteria and their novel regulatory mechanisms require further investigation