Adaptive Exponential Stabilization for a Class of Stochastic Nonholonomic Systems

This paper investigates the adaptive stabilization problem for a class of stochastic nonholonomic systems with strong drifts. By using input-state-scaling technique, backstepping recursive approach, and a parameter separation technique, we design an adaptive state feedback controller. Based on the switching strategy to eliminate the phenomenon of uncontrollability, the proposed controller can guarantee that the states of closed-loop system are global bounded in probability

When remembering and perceiving collide: the effect of visual distraction on long term memory retrieval

University of Minnesota Ph.D. dissertation. December 2014. Major: Psychology. Advisor: Wilma Koutstaal and Stephen Engel. 1 computer file (PDF); v, 109 pages.In seeking to retrieve goal-relevant information from long-term memory we face many obstacles that place demands on top-down cognitive control. Some of the obstacles are internal: there may be one or many associated mnemonic contenders for a target memory, or target memory representation may itself be weak. Other obstacles are external: our attention may be captured by environmental distracting perceptual events. Yet little is known about if, or how, these internal and external obstacles jointly influence successful memory retrieval. In three sets of experiments, we investigated the effects of internal interference (selection demand and retrieval demand) and external perceptual distraction on long-term memory retrieval. To test the generality of the effects, and to enhance ecological validity, we examined both semantic and episodic memory retrieval, used both static and dynamic visual distraction, and employed both abstract and semantically meaningful scenes as distraction images.For both the episodic and the semantic memory tasks, we found, in line with previous research, that as internal mnemonic competition increased, retrieval accuracy decreased and retrieval time increased, and, as the association strength between a given retrieval cue and a target memory increased, retrieval accuracy increased and retrieval time decreased. Unlike previous findings, visual distraction resulted in small effects on memory accuracy (average effect size d of .25), whereas it resulted in large effects on memory retrieval time (average effect size d of .99, average response cost of 135ms). Notably, there was little evidence that perceptual distraction imposed greater costs when there were many internal memory contenders (high selection demand) or when the target memory was weak (high retrieval demand). The non-interactive effects suggest a type of serial gating effect in which external perceptual versus internal mnemonic calls on our attentional resources are met successively (or alternately) rather than simultaneously. From a practical standpoint, particularly where decisions and actions need to be taken quickly, visual distraction should be minimized. Visual distraction may impede our ready and fluent access to even well-learned information, with implications for cognitive performance in contexts ranging from classrooms to emergency rooms, from creative idea generation sessions to witness testimony in legal settings

Essays on Pricing Behaviors of Energy Commodities

This dissertation investigates the pricing behaviors of two major energy commodities, U.S. natural gas and crude oil, using times series models. It examines the relationships between U.S. natural gas price variations and changes in market fundamentals within a two-state Markov-switching framework. It is found that the regime-switching model does a better forecasting job in general than the linear fundamental model without regime-switching framework, especially in the case of 1-step-ahead forecast. Studies are conducted of the dynamics between crude oil price and U.S. dollar exchange rates. Empirical tests are applied to both full sample (1986—2010) and subsample (2002—2010) data. It is found that causality runs in both directions between the oil and the dollar. Meanwhile, a theoretical 5-country partial dynamic portfolio model is constructed to explain the dynamics between oil and dollar with special attention to the roles of China and Russia. It is shown that emergence of China‘s economy enhances the linkage between oil and dollar due to China's foreign exchange policy. Further research is dedicated to the role of speculation in crude oil and natural gas markets. First a literature review on theory of speculation is conducted. Empirical studies on speculation in commodity markets are surveyed, with special focus on energy commodity market. To test the theory that speculation may affect commodity prices by exaggerating the signals sent by market fundamentals, this essay utilizes the forecast errors from the first essay to investigate the forecasting ability of speculators' net long positions in the market. Limited evidence is provided to support the bubble theory in U.S. natural gas market. In conclusion, this dissertation explores both fundamentals and speculators' roles in the U.S. natural gas and global crude oil markets. It is found that market fundamentals are the major driving forces for the two energy commodities price booms seen during the past several years

Is the status of gold threatened by Bitcoin?

This paper evinces the ability of gold to avoid risks during periods with great fluctuations in the Bitcoin market. We apply bootstrap full- and subsample rolling-window Granger causality tests to explore the causal relationship between Bitcoin price (BCP) and gold price (GP). The empirical results show that an increase in BCP can cause GP to decrease, indicating that the prosperity of the Bitcoin market undermines the hedging ability of gold. However, a decrease in BCP causes GP to increase, and it also emphasizes that the ability of gold to avoid risks persists. Hence, the status of gold will not be completely threatened by Bitcoin, and they are complementary to each other instead of in competition. In turn, both positive and negative influences of GP on BCP suggest that fluctuations in BCP can be predicted through the gold market. In situations of severe global uncertainty and complicated investment environments, investors can benefit from complementary markets to optimize their asset allocation. Additionally, countries can grasp the trends in Bitcoin and gold prices to prevent large fluctuations in both markets and to reduce the uncertainty of the financial system

Improved Insulin Resistance and Lipid Metabolism by Cinnamon Extract through Activation of Peroxisome Proliferator-Activated Receptors

Peroxisome proliferator-activated receptors (PPARs) are transcriptional factors involved in the regulation of insulin resistance and adipogenesis. Cinnamon, a widely used spice in food preparation and traditional antidiabetic remedy, is found to activate PPARγ and α, resulting in improved insulin resistance, reduced fasted glucose, FFA, LDL-c, and AST levels in high-caloric diet-induced obesity (DIO) and db/db mice in its water extract form. In vitro studies demonstrate that cinnamon increases the expression of peroxisome proliferator-activated receptors γ and α (PPARγ/α) and their target genes such as LPL, CD36, GLUT4, and ACO in 3T3-L1 adipocyte. The transactivities of both full length and ligand-binding domain (LBD) of PPARγ and PPARα are activated by cinnamon as evidenced by reporter gene assays. These data suggest that cinnamon in its water extract form can act as a dual activator of PPARγ and α, and may be an alternative to PPARγ activator in managing obesity-related diabetes and hyperlipidemia

NGX6 gene mediated by promoter methylation as a potential molecular marker in colorectal cancer

<p>Abstract</p> <p>Background</p> <p>Nasopharyngeal carcinoma associated gene 6 (NGX6) is down-regulated in most colon cancer cell lines and tumor tissues when compared with their normal tissue samples. As a novel suppress tumor gene, it could inhibit colon cancer cell growth and cell cycle progression. However, little is known about the transcriptional mechanisms controlling NGX6 gene expression. Recent findings suggest that epigenetic inactivation of multiple tumor suppressor genes plays an important role in the tumorigenesis of colorectal carcinoma (CRC). In this study, we explored the role of DNA methylation in regulation of NGX6 transcription.</p> <p>Methods</p> <p>In the present study, we cloned the NGX6 promoter with characteristics of a CpG island by luciferase reporter assay. Then, the CpG methylation status around the NGX6 promoter region in colon cancer cell lines and colorectal tumor tissues was examined by methylation-specific PCR and bisulfite DNA sequencing. Finally, 5-Aza-2'-deoxycytidine (5-Aza-dC) treatment was used to confirm the correlation between NGX6 promoter methylation and its gene inactivation.</p> <p>Results</p> <p>The sequence spanning positions -157 to +276 was identified as the NGX6 promoter, in which no canonical TATA boxes were found, while two CAAT boxes and GC boxes were discovered. Methylation status was observed more frequently in 40 colorectal cancer samples than in 40 adjacent normal mucosa samples (18/40 versus 7/40; P < 0.05). An analysis correlating gene methylation status with clinicopathological cancer features revealed that dense methylation of the NGX6 promoter was associated with colorectal cancer patients age (P < 0.05). Moreover, a trend was shown toward metastasis status and primary site in colorectal carcinomas with NGX6 promoter methylation (p = 0.056 and P = 0.067, respectively). In addition, 5-Aza-dC could induce NGX6 mRNA expression and NGX6 promoter demethylation in HT-29 cells.</p> <p>Conclusions</p> <p>Down-regulation of NGX6 gene is related to the promoter methylation. DNA methylation of NGX6 promoter might be a potential molecular marker for diagnosis or prognosis, or serve as a therapeutic target.</p

TOPIC: A Parallel Association Paradigm for Multi-Object Tracking under Complex Motions and Diverse Scenes

Video data and algorithms have been driving advances in multi-object tracking (MOT). While existing MOT datasets focus on occlusion and appearance similarity, complex motion patterns are widespread yet overlooked. To address this issue, we introduce a new dataset called BEE23 to highlight complex motions. Identity association algorithms have long been the focus of MOT research. Existing trackers can be categorized into two association paradigms: single-feature paradigm (based on either motion or appearance feature) and serial paradigm (one feature serves as secondary while the other is primary). However, these paradigms are incapable of fully utilizing different features. In this paper, we propose a parallel paradigm and present the Two rOund Parallel matchIng meChanism (TOPIC) to implement it. The TOPIC leverages both motion and appearance features and can adaptively select the preferable one as the assignment metric based on motion level. Moreover, we provide an Attention-based Appearance Reconstruct Module (AARM) to reconstruct appearance feature embeddings, thus enhancing the representation of appearance features. Comprehensive experiments show that our approach achieves state-of-the-art performance on four public datasets and BEE23. Notably, our proposed parallel paradigm surpasses the performance of existing association paradigms by a large margin, e.g., reducing false negatives by 12% to 51% compared to the single-feature association paradigm. The introduced dataset and association paradigm in this work offers a fresh perspective for advancing the MOT field. The source code and dataset are available at https://github.com/holmescao/TOPICTrack

Adaptive Stabilization of Stochastic Nonlinear Systems Disturbed by Unknown Time Delay and Covariance Noise

This paper considers a more general stochastic nonlinear time-delay system driven by unknown covariance noise and investigates its adaptive state-feedback control problem. As a remarkable feature, the growth assumptions imposed on delay-dependent nonlinear terms are removed. Then, with the help of Lyapunov-Krasovskii functionals and adaptive backstepping technique, an adaptive state-feedback controller is constructed by overcoming the negative effects brought by unknown time delay and covariance noise. Based on the designed controller, the closed-loop system can be guaranteed to be globally asymptotically stable (GAS) in probability. Finally, a simulation example demonstrates the effectiveness of the proposed scheme