In his seminal book, Shewhart (1931) makes no demand on the distribution of the characteristic to be plotted on a control chart. How then can we explain the idea that normality is, if not required, at least highly desirable? I believe that it has come about through the many statistical studies of control-chart behavior. If one is to study how a control chart behaves, it is necessary to relate it to some distribution. The obvious choice is the normal distribution because of its ubiquity as a satisfactory model. This is bolstered by the existence of the Central Limit Theorem.

Sampling: Design and Analysis

2011 international joint conference on neural networks (ijcnn)

Abdominal aortic aneurysm (AAA) is a significant cause of mortality in older adults. A key mechanism implicated in AAA pathogenesis is inflammation and the associated production of reactive oxygen species (ROS) and oxidative stress. These have been suggested to promote degradation of the extracellular matrix (ECM) and vascular smooth muscle apoptosis. Experimental and human association studies suggest that ROS can be favourably modified to limit AAA formation and progression. In the present review, we discuss mechanisms potentially linking ROS to AAA pathogenesis and highlight potential treatment strategies targeting ROS. Currently, none of these strategies has been shown to be effective in clinical practice.

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Oxidative stress and abdominal aortic aneurysm: potential treatment targets.

Objective— Recent evidence suggests an important role for angiotensin-converting enzyme 2 (ACE2) in limiting abdominal aortic aneurysm (AAA) This study examined the effect of ACE2 deficiency on AAA development and the efficacy of resveratrol to upregulate ACE2 in experimental AAA Approach and Results— Ace2 deletion in apolipoprotein-deficient mice ( ApoE −/ − Ace2 −/y ) resulted in increased aortic diameter and spontaneous aneurysm of the suprarenal aorta associated with increased expression of inflammation and proteolytic enzyme markers In humans, serum ACE2 activity was negatively associated with AAA diagnosis ACE2 expression was lower in infrarenal biopsies of patients with AAA than organ donors AAA was more severe in ApoE −/− Ace2 −/y mice compared with controls in 2 experimental models Resveratrol (005/100-g chow) inhibited growth of pre-established AAAs in ApoE −/− mice fed high-fat chow and infused with angiotensin II continuously for 56 days Reduced suprarenal aorta dilatation in mice receiving resveratrol was associated with elevated serum ACE2 and increased suprarenal aorta tissue levels of ACE2 and sirtuin 1 activity In addition, the relative phosphorylation of Akt and ERK (extracellular signal-regulated kinase) 1/2 within suprarenal aorta tissue and gene expression for nuclear factor of kappa light polypeptide gene enhancer in B cells 1, angiotensin type-1 receptor, and metallopeptidase 2 and 9 were significantly reduced Upregulation of ACE2 in human aortic smooth muscle cells by resveratrol in vitro was sirtuin 1-dependent Conclusions— This study provides experimental evidence of an important role for ACE2 in limiting AAA development and growth Resveratrol upregulated ACE2 and inhibited AAA growth in a mouse model

Resveratrol inhibits growth of experimental abdominal aortic aneurysm associated with upregulation of angiotensin-converting enzyme 2

Background Abdominal aortic aneurysm (AAA), a progressive segmental abdominal aortic dilation, is associated with high mortality. AAA is characterized by inflammation, smooth muscle cell (SMC) depletion and extracellular matrix (ECM) degradation. Surgical intervention and endovascular therapy are recommended to prevent rupture of large AAAs. Unfortunately, there is no reliable pharmacological agent available to limit AAA expansion. In the past decades, extensive investigations and a body of ongoing clinical trials aimed at defining potent treatments to inhibit and even regress AAA growth. Conclusion In this review, we summarized recent progress of potential strategies, particularly macrolides, tetracyclines, statins, angiotensin converting enzyme inhibitors, angiotensin receptor blocker, corticosteroid, anti-platelet drugs and mast cell stabilizers. We also consider recently identified novel molecular targets, which have potential to be translated into clinical practice in the future.

Pharmacological Therapy of Abdominal Aortic Aneurysm: An Update.

AAA (abdominal aortic aneurysm) is an important cause of sudden death in older adults, but there is no current effective drug therapy for this disease. The UCNs (urocortins1-3) and their receptors: CRFR (corticotrophin-releasing factor receptor)-1 and -2 have been implicated in various CVDs (cardiovascular diseases). We assessed the relative expression of UCN1-3 in AAA by qRT-PCR (quantitative reverse transcription-PCR) and ELISA, and examined in vitro how UCN2 affects human aortic VSMC (vascular smooth muscle cell) Akt phosphorylation, pro-inflammatory cytokine IL (interleukin)-6 secretion, proliferation, cell cycle and apoptosis. UCN2 and CRFR2 expression were significantly up-regulated in biopsies from the AAA body. AAA body biopsies released high amounts of UCN2 in vitro. Median plasma UCN2 concentrations were 2.20 ng/ml (interquartile range 1.14-4.55 ng/ml, n=67) in AAA patients and 1.11 ng/ml (interquartile range 0.76-2.55 ng/ml, n=67) in patients with non-aneurysmal PAD (peripheral artery disease) (P=0.001). Patients with UCN2 in the highest quartile had a 4.12-fold (95% confidence interval, 1.37-12.40) greater prevalence of AAA independent of other risk factors, P=0.012. In vitro, UCN2 significantly inhibited VSMC Akt phosphorylation and proliferation in a dose-dependent manner. UCN2 induced VSMC G1 cell-cycle arrest and increased IL-6 secretion over 24 h. The CRFR2 antagonist astressin-2B significantly abrogated the effects of UCN2 on VSMCs. In conclusion, UCN2 is significantly associated with AAA and inhibits VSMC proliferation by inducing a G1 cell cycle arrest suggesting a plausible regulatory role in AAA pathogenesis.

Urocortin 2 is associated with abdominal aortic aneurysm and mediates anti-proliferative effects on vascular smooth muscle cells via corticotrophin releasing factor receptor 2.

Information visualization is essential for improving effectiveness and efficiency of data exploration and knowledge discovery. Therefore, visualization has been used in a wide range of fields from biology, medicine, criminal activity analysis to business and education. Information visualization has become more important than ever as the amount of data being generated has increased dramatically in recent years. One of the major difficulties of information visualization is performance, and this is even more critical when visualizing big data. One potential solution to this challenge is data sampling while maintaining fidelity of visual representation. In this paper, we propose two new centrality clustering-based sampling approaches that apply centrality measures on clusters of data points in order to make more informed sampling than random sampling approaches. We evaluate the new methods on graph data sets. The results show that the new methods significantly outperform existing data sampling methods in term of perceived differences and their ability to preserve essential visual information. Moreover computational complexity is comparable or even better than simple random sampling methods.

Centrality clustering-based sampling for big data visualization

Learning now occurs in various manners in social networks, utilizing practice communities and learning networks. In this context, students are interested in exploring learning activities of other students without having to read through large quantities of textual content. Students tend to be interested in finding information concerning their majors, contents of their subjects and their co-learners. However, with the huge amount of information available, it is difficult for users to identify relevant information. Visualization comes in to help improve the situation. In this paper, we identify opportunities for deploying visualization in educational social networks to enhance learners' efficiency, effectiveness and learning experiences. We present a new learning space model designed to capture learning activities in educational social networks. A new 3D visualization system for the learning space model is also developed to help users obtain a better understanding of learning activities in social networks. We evaluate our approaches on educational social networks using real data. The evaluation results show that our approach of visualizing learning activities helps learners grasp a better overview of their study environment. Also, the learning process is perceived as easier, more engaging and more fun for the users, compared to traditional ways of displaying information.

Tam Thanh Nguyen

Papers

Urocortin 2 is associated with abdominal aortic aneurysm and mediates anti-proliferative effects on vascular smooth muscle cells via corticotrophin releasing factor receptor 2.

Centrality clustering-based sampling for big data visualization

Learning space model for educational social networks