A Mixed-Integer SDP Solution Approach to Distributionally Robust Unit Commitment with Second Order Moment Constraints

A power system unit commitment (UC) problem considering uncertainties of renewable energy sources is investigated in this paper, through a distributionally robust optimization approach. We assume that the first and second order moments of stochastic parameters can be inferred from historical data, and then employed to model the set of probability distributions. The resulting problem is a two-stage distributionally robust unit commitment with second order moment constraints, and we show that it can be recast as a mixed-integer semidefinite programming (MI-SDP) with finite constraints. The solution algorithm of the problem comprises solving a series of relaxed MI-SDPs and a subroutine of feasibility checking and vertex generation. Based on the verification of strong duality of the semidefinite programming (SDP) problems, we propose a cutting plane algorithm for solving the MI-SDPs; we also introduce a SDP relaxation for the feasibility checking problem, which is an intractable biconvex optimization. Experimental results on a IEEE 6-bus system are presented, showing that without any tunings of parameters, the real-time operation cost of distributionally robust UC method outperforms those of deterministic UC and two-stage robust UC methods in general, and our method also enjoys higher reliability of dispatch operation

Fish Biodiversity Conservation and Restoration, Yangtze River Basin, China, Urgently Needs ‘Scientific’ and ‘Ecological’ Action

Although many significant policies and legislation have been put forth by the Chinese government aiming toward “ecological civilization” for the aquatic environment, in practice, the situation is still undesirable. A pioneering multi-year study has since been conducted on the East Tiaoxi River (a major tributary of the renowned Yangtze River), focusing on fish distribution, influencing factors and habitat requirements, and river health as well. This revealed certain key species, hotspot protection areas, negative impacts of local anthropogenic activities, and inappropriate perceptions and practices of conservation and restoration. We found that not all fish species were equally conserved and that the supposedly ecological engineering measures were initiated without regard for ecological integrity. Our exemplary study appreciates scientific basis and truly ecological notion, and urgently advocates comprehensive and continuous basin-scale scientific investigation of fish biodiversity, and “ecological river”-oriented conservation and restoration action for the Yangtze River Basin and broader areas of China

Genetic variations affecting serum carcinoembryonic antigen levels and status of regional lymph nodes in patients with sporadic colorectal cancer from Southern China.

BACKGROUND: Serum carcinoembryonic antigen (sCEA) level might be an indicator of disease. Indeed, an elevated sCEA level is a prognostic factor in colorectal cancer (CRC) patients. However, the genetic determinants of sCEA level in healthy and CRC population remains unclear. Thus we investigated the genetic markers associated with elevated serum sCEA level in these two populations and its clinical implications. METHODS AND FINDINGS: Genome-wide association study (GWAS) was conducted in a cohort study with 4,346 healthy male adults using the Illumina Omni 1 M chip. Candidate SNPs associated with elevated sCEA levels were validated in 194 CRC patients on ABI Taqman platform. Eight candidate SNPs were validated in CRC patients. The rs1047781 (chr19- FUT2) (A/T) was associated with elevated sCEA levels, and rs8176746 (chr9- ABO) was associated with the regional lymph metastasis in the CRC patients. The preoperative sCEA level was a risk factor for tumor recurrence in 5 years after operation (OR = 1.427, 95% CI: 1.005∼1.843, P = 0.006). It was also one of the risk factors for regional lymph node metastasis (OR = 2.266, 95% CI: 1.196∼4.293, P = 0.012). The sCEA level in rs1047781-T carriers was higher than that in the A carriers in CRC patients without lymph node metastasis (P = 0.006). The regional lymph node metastasis in patients with homozygote AA of rs8176746 was more common than that in the heterozygote AG carriers (P = 0.022). In addition, rs1047781-AT and TT CRC patients exhibited a worse disease-free survival than AA genotype carriers (P = 0.023). CONCLUSIONS: We found candidate SNPs associated with elevated sCEA levels in both healthy males and CRC population. Rs1047781 (chr19- FUT2) may be the susceptible locus for recurrence of CRC in a population from Southern China

Tumor-free survival analysis of CRC patients stratified by rs1047781+rs8176746 genotypes.

<p>Subjects were divided into 2 groups by genetic maker (rs1047781+rs8176746). Group 1 was rs1047781 (AA) +rs8176746 (AA+AG) and group 2 was rs1047781 (AT+TT) +rs8176746 (AA+AG). The disease-free time of subgroups was significantly different (<i>p</i> = 0.023).</p

Tumor-free survival analysis of CRC patients stratified by preoperative sCEA levels.

<p>The tumor-free time was different between CRC patients with preoperative CEA levels at <5 and ≥5 ng/ml (<i>p</i> = 0.001).</p

Logistic regression analysis of risk factors influencing 5-yr recurrence in CRC patients.¹

1<p>The patients with distant organ metastases were excluded.</p

Tumor-free survival analysis of CRC patients stratified by rs1047781.

<p>With rs1047781 (chr-19 FUT2), the disease-free time of CRC patients grouped by allelic genotypes (AA, AT and TT) was not significantly different (<i>p</i> = 0.066).</p

Association between RLN metastasis and preoperative sCEA levels (stratified by rs1047781 genotypes).

1<p>The values of CEA levels and times were represented by median values, and the range of sCEA level is shown.</p>2<p>St. J-T statistic was represented using the standard statistic of Jonckheere-Terpstra test.</p>3<p>The distant organs included liver, lung and omentum.</p>4<p>The rate of tumor lymph node metastasis was adjusted.</p>5<p>The statistical evaluation for CEA levels was performed by Mann-Whitney U test.</p