Statistical Nested Sensor Array Signal Processing

Source number detection and direction-of-arrival (DOA) estimation are two major applications of sensor arrays. Both applications are often confined to the use of uniform linear arrays (ULAs), which is expensive and difficult to yield wide aperture. Besides, a ULA with N scalar sensors can resolve at most N − 1 sources. On the other hand, a systematic approach was recently proposed to achieve O(N 2 ) degrees of freedom (DOFs) using O(N) sensors based on a nested array, which is obtained by combining two or more ULAs with successively increased spacing. This dissertation will focus on a fundamental study of statistical signal processing of nested arrays. Five important topics are discussed, extending the existing nested-array strategies to more practical scenarios. Novel signal models and algorithms are proposed. First, based on the linear nested array, we consider the problem for wideband Gaussian sources. To employ the nested array to the wideband case, we propose effective strategies to apply nested-array processing to each frequency component, and combine all the spectral information of various frequencies to conduct the detection and estimation. We then consider the practical scenario with distributed sources, which considers the spreading phenomenon of sources. Next, we investigate the self-calibration problem for perturbed nested arrays, for which existing works require certain modeling assumptions, for example, an exactly known array geometry, including the sensor gain and phase. We propose corresponding robust algorithms to estimate both the model errors and the DOAs. The partial Toeplitz structure of the covariance matrix is employed to estimate the gain errors, and the sparse total least squares is used to deal with the phase error issue. We further propose a new class of nested vector-sensor arrays which is capable of significantly increasing the DOFs. This is not a simple extension of the nested scalar-sensor array. Both the signal model and the signal processing strategies are developed in the multidimensional sense. Based on the analytical results, we consider two main applications: electromagnetic (EM) vector sensors and acoustic vector sensors. Last but not least, in order to make full use of the available limited valuable data, we propose a novel strategy, which is inspired by the jackknifing resampling method. Exploiting numerous iterations of subsets of the whole data set, this strategy greatly improves the results of the existing source number detection and DOA estimation methods

Synthesis of 4′,7-Diacetoxyapigenin and Its Apoptotic Induction in Human Hep G2 Cells

In this study, 4′,7-diacetoxyapigenin [4-(7-acetoxy-5-hydroxy-4-oxo-4H-chromen-2-yl) phenyl acetate] was synthesized for the first time. Its chemical structure was identified by UV, ESI-MS, 1H and 13C-NMR. It could inhibit the proliferation of Hep G2 cells in a dose-dependent manner and induce the significant increase of the G0/G1 cell population. After treatment by 4′,7-diacetoxyapigenin, phosphatidylserine of Hep G2 cells could significantly translocate to the surface of the membrane. The increase of an early apoptotic population was observed by both annexin-FITC and PI staining. It was concluded that 4′,7-diacetoxyapigenin not only induced cells to enter into apoptosis, but also affected the progress of the cell cycle

Food Supply Value and Their Factors of Three Pond Aquaculture Ecosystems: A Case Study of Shanghai

Studies on food supply values, the basis of eco-service values, and their factors of different pond aquaculture ecosystems are helpful to explain the influences of the inputted factors and their variations among these ecosystems and provide information for stakeholders to adjust their decisions and behaviors to increase their total eco-service values. On the basis of continued records from 2011 to 2012 of 18 ponds of three pond aquaculture ecosystems, namely Litopenaeus vannamei, Macrobrachium nippponensis and carp fresh water pond aquaculture ecosystems in Qingpu, Fengxian, and Jiading, three suburban districts of Shang, this paper analyzed the costs, returns, net food supply values and their regional and temporal fluctuations. The results showed that: (1) the net food supply values of the three ecosystems are 143252.4, 135883.7, and 52623.1Yuan/Ha in 2011 correspondently, with the Litopenaeus vannamei pond aquaculture ecosystem (LVPAE) ranking highest and the carp pond aquaculture ecosystem (CPAE) lowest among them, and the trend was same in 2012, but the values decreased than that of 2011 with the rate of 30.0%( LVPAE), 38.0 %( Macrobrachium nippponensis pond aquaculture ecosystem, MNPAE) and 13.7 %( CPAE). (2)The dominant factors of the net food supply values of these ecosystems are the produce price and variable costs; fry and feed costs are the main variable factors producing the noticeable difference among the ecosystems. (3) The cost-benefit ratio of per unit product of the CPAE, LVPAE and MNPAE changed from 27.5%,91.7%,129.0% in 2011 to 23.0%,73.8% and 63.8% in 2012, with the CPAE ranked lowest among them in both years.(4) For all the three ecosystems, their net food supply values may not always change in same trends with their net eco-service values, if stakeholders want to keep an balance between these two types of values, MNPAE should be encouraged in these districts

Association of BMI with total mortality and recurrent stroke among stroke patients: a meta-analysis of cohort studies

Background and aims Studies of the association between obesity and total mortality and recurrent stroke events have shown contradictory results. Therefore, we aimed to conduct a meta-analysis to examine the association of body mass index (BMI) with total mortality and recurrent stroke events among patients after stroke onset. Methods We performed an electronic search of PubMed, EMBASE and the Cochrane Library Database, as well as a bibliography review to identify relevant cohort studies published prior to 15th December 2015. Estimates of relative risks (RRs) and corresponding 95% confidence intervals (CIs) comparing underweight, overweight and obese groups with normal weight were pooled using random effects models. Results In total, 15 studies with 122,472 stroke patients were eligible for inclusion in the meta-analysis. Compared with the normal weight group, obese stroke patients had a significant decreased risk for total mortality (RR\ua0=\ua00.83, 95% CI, 0.73–0.93, p\ua0=\ua00.002), while underweight patients had a significant increased risk for total mortality (RR\ua0=\ua01.54, 95% CI, 1.31–1.82, p\ua0=\ua03.66\ua0×\ua010). A similar, but not significant, association of BMI categories with recurrent stroke events was also observed. Furthermore, the dose-response meta-analysis identified a nonlinear trend for total mortality and a linear trend for recurrent stroke events, associated with BMI. Conclusions Our results suggested that obesity may have a protective effect on total mortality and recurrent stroke events among patients with established stroke

Physicochemical Properties and Antioxidant Activities of Luteolin-Phospholipid Complex

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Toxicity Assessment of a Single Dose of Poly(ethylene glycol) Diglycidyl Ether (PEGDE) Administered Subcutaneously in Mice

Poly(ethylene glycol) diglycidyl ether (PEGDE) is widely used to cross-link polymers, particularly in the pharmaceutical and biomaterial sectors. However, the subcutaneous toxicity of PEGDE has not yet been assessed. PEGDE samples (500–40,000 μg/mouse) were subcutaneously injected into the paraspinal dorsum of BALB/c male mice. Cage-side observations were carried out with measurement of organ weight, body weight variation, and feed intake, as well as histopathological characterization on day 28 post-exposure. Mice that received 40,000 μg of PEGDE showed severe toxic response and had to be euthanized. Subcutaneous injection of PEGDE did not alter feed intake and organ weight; however, the body weight variation of mice injected with 20,000 μg of PEGDE was significantly lower than that of the other groups. Exposure to 10,000 and 20,000 μg of PEGDE induced epidermal ulcer formation and hair loss. The histology of skin tissue in mice administered with 20,000 μg of PEGDE showed re-epithelialized or unhealed wounds. However, the liver, spleen, and kidneys were histologically normal. Collectively, PEGDE, particularly above 10,000 μg/mouse, caused subcutaneous toxicity with ulceration, but no toxicity in the other organs. These results may indicate the optimal concentration of subcutaneously injected PEGDE

Serum-Based Culture Conditions Provoke Gene Expression Variability in Mouse Embryonic Stem Cells as Revealed by Single-Cell Analysis

Variation in gene expression is an important feature of mouse embryonic stem cells (ESCs). However, the mechanisms responsible for global gene expression variation in ESCs are not fully understood. We performed single-cell mRNA-seq analysis of mouse ESCs and uncovered significant heterogeneity in ESCs cultured in serum. We define highly variable gene clusters with distinct chromatin states and show that bivalent genes are prone to expression variation. At the same time, we identify an ESC-priming pathway that initiates the exit from the naive ESC state. Finally, we provide evidence that a large proportion of intracellular network variability is due to the extracellular culture environment. Serum-free culture reduces cellular heterogeneity and transcriptome variation in ESCs