Finding optimal control policy by using dynamic programming in conjunction with state reduction

In this paper we study the problem of finding optimal control policy for probabilistic Boolean networks (PBNs). Previous works have been done by using dynamic programming-based (DP) method. However, due to the high computational complexity of PBNs, DP method is computationally inefficient for large networks. Inspired by the state reduction strategies studied in [10], we consider using dynamic programming in conjunction with state reduction approach to reduce the computational cost of DP method. Numerical examples are given to demonstrate the efficiency of our proposed method. © 2011 IEEE.published_or_final_versionThe 2011 IEEE International Conference on Systems Biology (ISB), Zhuhai, China, 2-4 September 2011. In Proceedings of ISB, 2011, p. 274-27

Contingent proletarianization of creative labor: Deskilling in the Xianyou classical furniture cluster

Champions of creative economy maintain that, unlike labor in manufacturing, labor in the creative industries is independent and innovative. They also claim that we are witnessing a linear transition from a manual to a creative labor-based economy. We argue against this idea of a sweeping, historical transition and instead posit that the labor process can easily switch from one to the other, depending on market conditions. We illustrate this theoretical point through an empirical study of the classic furniture industry cluster in Xianyou, China. Until around 2005, the region housed a typical low-skill, low-value added manufacturing cluster of small size. Since then it quickly transformed into a creative industry cluster where a small number of craftsmen performed both creative and manual work. However, the recent growth in the demand for classic furniture has enabled firms to mechanize the production process thereby creating new divisions of labor and turning the majority of the workforce into simple manual workers. At the same time, those who specialize in what remains creative in the production process are now liberated from manual work and enjoy greater creative freedom and higher status. Based on these findings, we conclude that, the transformation between creative and non-creative labor is reversible, industry-specific, and contingent upon the market rather than irreversible and economy-wide

Phonological Units in Spoken Word Production: Insights from Cantonese

published_or_final_versio

Metformin Use and Gastric Cancer Risk in Diabetic Patients After Helicobacter pylori Eradication

Background: Although prior studies showed metformin could reduce gastric cancer (GC) risk in patients with diabetes mellitus (DM), they failed to adjust for Helicobacter pylori infection and glycemic control. We aimed to investigate whether metformin reduced GC risk in H. pylori -eradicated diabetic patients and its association with glycemic control. Methods: This was a territory-wide cohort study using hospital registry database, recruiting all diabetic patients who were prescribed clarithromycin-based triple therapy for H. pylori infection from 2003 to 2012. Subjects were observed from H. pylori therapy prescription until GC diagnosis, death or end of study (December 2015). Exclusion criteria included GC diagnosed within first year of H. pylori therapy, prior history of GC or gastrectomy, and failure of H. pylori eradication. The hazard ratio (HR) of GC with metformin (defined as at least 180-day use) was estimated by Cox model with propensity score adjustment for covariates (age, sex, comorbidities, medications [including insulin], and time-weighted average hemoglobin A1c [HbA1c]). All statistical tests were two-sided. Results: During a median follow-up of 7.1 years (IQR:4.7–9.8), 37 (0.51%) of 7,266 diabetic patients developed GC at a median age of 76.4 years (IQR: 64.8–81.5 years). Metformin use was associated with a reduced GC risk (adjusted HR:0.49; 95% CI:0.24–0.98). There was a trend towards a lower GC risk with increasing duration (ptrend =0.01) and dose of metformin (ptrend=0.02) HbA1c level was not an independent risk factor for GC. Conclusions: Metformin use was associated with a lower GC risk among H. pylori -eradicated diabetic patients in a duration- and dose-response manner, which was independent of HbA1c level

Principal-agent Theory Based Risk Allocation Model for Virtual Enterprise

In this paper, we consider a risk analysis model for Virtual Enterprise (VE) by exploring the state of the art of the principal-agent theory. In particular, we deal with the problem of allocating the cost of risk between two parties in a VE, namely, the owner and the partner(s). We first consider the case of a single partner of VE with symmetric information or asymmetric information and then the case of multiple partners. We also build a model for the optimal contract of the risk allocation based on the principal-agent theory and analyze it through specific example. At last we consider the case of multiple principal with potentially many partners based on common agency.published_or_final_versio

On optimal control policy for Probabilistic Boolean Network: a state reduction approach

BACKGROUND: Probabilistic Boolean Network (PBN) is a popular model for studying genetic regulatory networks. An important and practical problem is to find the optimal control policy for a PBN so as to avoid the network from entering into undesirable states. A number of research works have been done by using dynamic programming-based (DP) method. However, due to the high computational complexity of PBNs, DP method is computationally inefficient for a large size network. Therefore it is natural to seek for approximation methods. RESULTS: Inspired by the state reduction strategies, we consider using dynamic programming in conjunction with state reduction approach to reduce the computational cost of the DP method. Numerical examples are given to demonstrate both the effectiveness and the efficiency of our proposed method. CONCLUSIONS: Finding the optimal control policy for PBNs is meaningful. The proposed problem has been shown to be ∑ p 2 - hard . By taking state reduction approach into consideration, the proposed method can speed up the computational time in applying dynamic programming-based algorithm. In particular, the proposed method is effective for larger size networks.published_or_final_versio

Generating probabilistic Boolean networks from a prescribed stationary distribution

Modeling gene regulation is an important problem in genomic research. Boolean networks (BN) and its generalization probabilistic Boolean networks (PBNs) have been proposed to model genetic regulatory interactions. BN is a deterministic model while PBN is a stochastic model. In a PBN, on one hand, its stationary distribution gives important information about the long-run behavior of the network. On the other hand, one may be interested in system synthesis which requires the construction of networks from the observed stationary distribution. This results in an inverse problem which is ill-posed and challenging. Because there may be many networks or no network having the given properties and the size of the inverse problem is huge. In this paper, we consider the problem of constructing PBNs from a given stationary distribution and a set of given Boolean Networks (BNs). We first formulate the inverse problem as a constrained least squares problem. We then propose a heuristic method based on Conjugate Gradient (CG) algorithm, an iterative method, to solve the resulting least squares problem. We also introduce an estimation method for the parameters of the PBNs. Numerical examples are then given to demonstrate the effectiveness of the proposed methods. © 2010 Elsevier Inc. All rights reserved.postprin

Finding optimal control policy in probabilistic Boolean networks with hard constraints by using integer programming and dynamic programming

Session 2 regularIn this paper, we study control problems of Boolean Networks (BNs) and Probabilistic Boolean Networks (PBNs). For BN CONTROL, by applying external control, we propose to derive the network to the desired state within a few time steps. For PBN CONTROL, we propose to find a control sequence such that the network will terminate in the desired state with a maximum probability. Also, we propose to minimize the maximum cost of the terminal state to which the network will enter. Integer linear programming and dynamic programming in conjunction with hard constraints are then employed to solve the above problems. Numerical experiments are given to demonstrate the effectiveness of our algorithms.We also present a hardness result suggesting that PBN CONTROL is harder than BN CONTROL. ©2010 IEEE.published_or_final_versio

Mechanism Design of Fashion Virtual Enterprise under Monitoring Strategy

published_or_final_versio

Distributions of colorectal cancer in two chinese cities with contrasting colorectal cancer epidemiology

BACKGROUND AND AIM: The incidence of colorectal cancer (CRC) is rising rapidly in Chinese. We studied the anatomic distributions and characteristics of CRC in Hong Kong (HK) and Chongqing (CQ) with different CRC epidemiology. METHODS: It was a retrospective study conducted in three large regional hospitals of the two cities. We identified all patients newly diagnosed with CRC between 2003 and 2012. The distribution and characteristics of CRC of the two cities were compared. RESULTS: 3,664 new cases of CRC were diagnosed within the study period. CRC was more common in men (>56%) in both cities. The mean age at diagnosis was significantly younger in CQ, the lower prevalence area, than in HK (62.1 vs 70.4 years; P <0.001). Rectal cancer was the predominant (61.3%) cancer in CQ, but only 18% of cancers in HK were rectal cancer (P = 0.0001). Right-sided colonic cancer, however, was more common in HK than CQ (27.2% vs 17.4%; P <0.001). Women had more right-sided colonic cancer than men in both cities (P < 0.002), and there was an age-related increase in right-sided colonic cancer in HK but not in CQ. Multivariate analysis showed that older age, female and living in HK were independent risk factors associated with right-sided colonic cancer. CONCLUSIONS: There are significant differences in the distribution of CRC between HK and CQ. The discrepancy may be partly accounted by older population and an increase in proximal colonic cancer, particularly in women, in HK.preprin