111 research outputs found
Alternating projections gridless covariance-based estimation for DOA
We present a gridless sparse iterative covariance-based estimation method
based on alternating projections for direction-of-arrival (DOA) estimation. The
gridless DOA estimation is formulated in the reconstruction of
Toeplitz-structured low rank matrix, and is solved efficiently with alternating
projections. The method improves resolution by achieving sparsity, deals with
single-snapshot data and coherent arrivals, and, with co-prime arrays,
estimates more DOAs than the number of sensors. We evaluate the proposed method
using simulation results focusing on co-prime arrays.Comment: 5 pages, accepted by (ICASSP 2021) 2021 IEEE International Conference
on Acoustics, Speech, and Signal Processin
Robust and Sparse M-Estimation of DOA
A robust and sparse Direction of Arrival (DOA) estimator is derived for array
data that follows a Complex Elliptically Symmetric (CES) distribution with
zero-mean and finite second-order moments. The derivation allows to choose the
loss function and four loss functions are discussed in detail: the Gauss loss
which is the Maximum-Likelihood (ML) loss for the circularly symmetric complex
Gaussian distribution, the ML-loss for the complex multivariate
-distribution (MVT) with degrees of freedom, as well as Huber and
Tyler loss functions. For Gauss loss, the method reduces to Sparse Bayesian
Learning (SBL). The root mean square DOA error of the derived estimators is
discussed for Gaussian, MVT, and -contaminated data. The robust SBL
estimators perform well for all cases and nearly identical with classical SBL
for Gaussian noise
Analysis of the proteome of human airway epithelial secretions.
BACKGROUND: Airway surface liquid, often referred to as mucus, is a thin layer of fluid covering the luminal surface that plays an important defensive role against foreign particles and chemicals entering the lungs. Airway mucus contains various macromolecules, the most abundant being mucin glycoproteins, which contribute to its defensive function. Airway epithelial cells cultured in vitro secrete mucins and nonmucin proteins from their apical surface that mimics mucus production in vivo. The current study was undertaken to identify the polypeptide constituents of human airway epithelial cell secretions to gain a better understanding of the protein composition of respiratory mucus.
RESULTS: Fifty-five proteins were identified in the high molecular weight fraction of apical secretions collected from in vitro cultures of well-differentiated primary human airway epithelial cells and isolated under physiological conditions. Among these were MUC1, MUC4, MUC5B, and MUC16 mucins. By proteomic analysis, the nonmucin proteins could be classified as inflammatory, anti-inflammatory, anti-oxidative, and/or anti-microbial.
CONCLUSIONS: Because the majority of the nonmucin proteins possess molecular weights less than that selected for analysis, it is theoretically possible that they may associate with the high molecular weight and negatively charged mucins to form a highly ordered structural organization that is likely to be important for maintaining the proper defensive function of airway mucus
Drosophila Porin/VDAC Affects Mitochondrial Morphology
Voltage-dependent anion channel (VDAC) has been suggested to be a mediator of mitochondrial-dependent cell death induced by Ca2+ overload, oxidative stress and Bax-Bid activation. To confirm this hypothesis in vivo, we generated and characterized Drosophila VDAC (porin) mutants and found that Porin is not required for mitochondrial apoptosis, which is consistent with the previous mouse studies. We also reported a novel physiological role of Porin. Loss of porin resulted in locomotive defects and male sterility. Intriguingly, porin mutants exhibited elongated mitochondria in indirect flight muscle, whereas Porin overexpression produced fragmented mitochondria. Through genetic analysis with the components of mitochondrial fission and fusion, we found that the elongated mitochondria phenotype in porin mutants were suppressed by increased mitochondrial fission, but enhanced by increased mitochondrial fusion. Furthermore, increased mitochondrial fission by Drp1 expression suppressed the flight defects in the porin mutants. Collectively, our study showed that loss of Drosophila Porin results in mitochondrial morphological defects and suggested that the defective mitochondrial function by Porin deficiency affects the mitochondrial remodeling process
The Constraint of a General Effective Potential in Vector Torsion Coupled Conformally Induced Gravity
It is found that the deviation of an effective potential from the quartic
form is related to the metric and vector torsion dependencies of the effective
potential in the vector torsion coupled conformally induced gravity.Comment: 3pages Revtex 3.0, no figur
Phase Transition in Conformally Induced Gravity with Torsion
We have considered the quantum behavior of a conformally induced gravity in
the minimal Riemann-Cartan space. The regularized one-loop effective potential
considering the quantum fluctuations of the dilaton and the torsion fields in
the Coleman-Weinberg sector gives a sensible phase transition for an
inflationary phase in De Sitter space. For this effective potential, we have
analyzed the semi-classical equation of motion of the dilaton field in the
slow-rolling regime.Comment: 7pages, no figur
Three-dimensional imaging of cell and extracellular matrix elasticity using quantitative micro-elastography
Funding: Australian Research Council; Cancer Council Western Australia; Industrial Transformation Training Centre; The William and Marlene Schrader Trust of the University of Western Australia.Recent studies in mechanobiology have revealed the importance of cellular and extracellular mechanical properties in regulating cellular function in normal and disease states. Although it is established that cells should be investigated in a three-dimensional (3-D) environment, most techniques available to study mechanical properties on the microscopic scale are unable to do so. In this study, for the first time, we present volumetric images of cellular and extracellular elasticity in 3-D biomaterials using quantitative micro-elastography (QME). We achieve this by developing a novel strain estimation algorithm based on 3-D linear regression to improve QME system resolution. We show that QME can reveal elevated elasticity surrounding human adipose-derived stem cells (ASCs) embedded in soft hydrogels. We observe, for the first time in 3-D, further elevation of extracellular elasticity around ASCs with overexpressed TAZ; a mechanosensitive transcription factor which regulates cell volume. Our results demonstrate that QME has the potential to study the effects of extracellular mechanical properties on cellular functions in a 3-D micro-environment.Publisher PDFPeer reviewe
Conformal Couplings in Induced Gravity
It is found that the induced gravity with conformal couplings requires the
conformal invariance in both classical and quantum levels for consistency. This
is also true for the induced gravity with an extended conformal coupling
interacting with torsion.Comment: 10 pages, Revtex3.0, to appear in General Relativity and Gravitatio
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