STOCHASTIC OPTIMIZATION: ALGORITHMS AND CONVERGENCE

Stochastic approximation is one of the oldest approaches for solving stochastic optimization problems. In the first part of the dissertation, we study the convergence and asymptotic normality of a generalized form of stochastic approximation algorithm with deterministic perturbation sequences. Both one-simulation and two-simulation methods are considered. Assuming a special structure on the deterministic sequence, we establish sufficient conditions on the noise sequence for a.s. convergence of the algorithm and asymptotic normality. Finally we propose ideas for further research in analysis and design of the deterministic perturbation sequences. In the second part of the dissertation, we consider the application of stochastic optimization problems to American option pricing, a challenging task particularly for high-dimensional underlying securities. For options where there are a finite number of exercise dates, we present a weighted stochastic mesh method that only requires some easy-to-verify assumptions and a method to simulate the behavior of underlying securities. The algorithm provides point estimates and confidence intervals for both price and value-at-risk. The estimators converge to the true values as the computational effort increases. In the third part, we deal with an optimization problem in the field of ranking and selection. We generalize the discussion in the literature to a non-Gaussian correlated distribution setting. We propose a procedure to locate an approximate solution, which can be shown to converge to the true solution asymptotically. The convergence rate is also provided for the Gaussian setting

Implementation of a CMOS Wallace-tree Multiplier

© ASEE 2009As slow and expensive operation units, multipliers are often the bottleneck limiting the overall performance of many computational VLSI circuits. Various CMOS multiplier architectures are available, such as the array multiplier, carry-save multiplier, and Wallace-tree multiplier. Wallace-tree multiplier has been a very popular design due to its fast speed, ease for modularization and fabrication. In this paper, the design and simulation of an 8-bit Wallace-tree multiplier with PSPICE is proposed. In order for comparison, an 8-bit CMOS array multiplier is also designed. The worst-case delay of both multiplier architectures are extracted and Wallace-tree multiplier demonstrates significant speed enhancement compared to CMOS array multiplier. Some efforts are made to further improve the performance of Wallace-tree multiplier. The revision in the circuit structure demonstrates effective speed improvement for the Wallace-tree multiplier

Power trading Raft consensus mechanism considering green certificate and carbon emission weights

The consensus mechanism is a critical technology in the power trading blockchain distributed power trading platforms, which are gradually being applied and promoted to achieve the “dual carbon” goal. Green-certificate trading and carbon emission trading systems help mobilize power generation enterprises to increase the generation of and investment in renewable energy, thereby becoming important factors in distributed power trading. Therefore, they should also be considered as factors in the consensus mechanism. This article first evaluates the green-certificate weight based on whether nodes possess green certificates, evaluates the carbon emission weight based on the carbon emission settlement of nodes in the previous cycle, and constructs a mechanism to evaluate a node’s weight. An improved Raft consensus algorithm based on node weight is then proposed. Nodes with greater weights are more likely to become leading nodes, promoting active compliance and green consumption by nodes and reducing carbon emissions. A simulation shows that the improved Raft consensus mechanism enhances the reliability of leading nodes, improves the efficiency of the distributed power transaction, increases the generation of renewable energy, and encourages the consumption of new energy

A phase III trial comparing an anionic phospholipid-based cream and aloe vera-based gel in the prevention of radiation dermatitis in pediatric patients

<p>Abstract</p> <p>Purpose</p> <p>Radiation dermatitis is a common side effect of radiation therapy (RT). In severe cases, RT must be interrupted until the skin heals, which can compromise treatment. The purpose of the study was to compare an anionic polar phospholipid (APP)-based cream and an aloe vera-based gel to determine their effectiveness in preventing and treating radiation dermatitis.</p> <p>Patients and methods</p> <p>Forty-five pediatric patients (median age, 11 years) with various diagnoses who received at least 23.4 Gy participated. APP cream and aloe vera gel were symmetrically applied within the irradiated field after each treatment. Three measures were collected before, during and after completion of treatment: subject's skin comfort, dermatologic assessment, and common toxicity criteria (CTC).</p> <p>Results</p> <p>Significant differences in specific variables favoring APP cream use were noted in some patients including skin comfort variables, dry (<it>p </it>= 0.002), soft (<it>p </it>= 0.057), feels good (<it>p </it>= 0.002), rough (<it>p </it>= 0.065), smooth (<it>p = 0.012</it>) and dermatologic variables, dryness (<it>p </it>= 0.013), erythema (<it>p </it>= 0.002) and peely (<it>p </it>= 0.008). Grouped CTC scores were supportive of APP cream (<it>p </it>= 0.004). In comparing the first and last assessments, two dermatologic variables, dryness (<it>p </it>= 0.035) and peely (<it>p </it>= 0.016), favored APP cream.</p> <p>Conclusion</p> <p>APP cream is more effective than aloe vera-based gel for prevention and treatment of radiation dermatitis.</p

Early malperfusion, ischemia reperfusion injury, and respiratory failure in acute complicated type B aortic dissection after thoracic endovascular repair

BACKGROUND: The aim of this study was to determine the early mortality and major complications of acute complicated type B aortic dissection (ACBD) after thoracic endovascular aortic repair (TEVAR). METHODS: Twenty-six consecutive patients with ACBD who underwent TEVAR were included. Clinical indications before TEVAR and in-hospital mortality and major complications after TEVAR were analyzed and compared with similar reports. RESULTS: TEVAR was technically successful in all cases. In-hospital mortality occurred in four patients (15%), and major complications occurred in an additional four patients (15%). Three of the four (75%) of the deaths were associated with malperfusion and ischemia reperfusion injury (IRI), and 3/4 (75%) of the major complications were caused by respiratory failure (RF). CONCLUSIONS: In-hospital mortality associated strongly with severe end-organ malperfusion and IRI, while major complications associated with RF, during TEVAR. Our results indicate that malperfusion, IRI and respiratory failure during TEVAR should be carefully monitored and aggressively treated

The SNP rs961253 in 20p12.3 Is Associated with Colorectal Cancer Risk: A Case-Control Study and a Meta-Analysis of the Published Literature

Background: Colorectal cancer (CRC) is the third common cancer and the fourth leading cause of cancer death worldwide. A single nucleotide polymorphism (SNP), rs961253 located in 20p12, was firstly described to be associated with the increased risk of CRC in a genome-wide association study; however, more recent replication studies yielded controversial results. Methodology/Principal Findings: A hospital-based case-control study in a Chinese population was firstly performed, and then a meta-analysis combining the current and previously published studies were conducted to explore the real effect of rs961253 in CRC susceptibility. In the Chinese population including 641 cases and 1037 controls, per-A-allele conferred an OR of 1.60 (95 % CI = 1.26–2.02) under additive model. In the meta-analysis including 29859 cases and 29696 controls, per-Aallele have an OR of 1.13 (95 % CI = 1.09–1.18) under a random-effects model due to heterogeneity (P = 0.019). Nevertheless, the heterogeneity can be totally explained by ethnicity, with the tau 2 reduced to 0 after including ethnicity in metaregression model. In stratified analysis by ethnicity, per-A-allele had ORs of 1.34 (95 % CI = 1.20–1.50) and 1.11 (95% CI = 1.08–1.14) for Asian and European, respectively, without heterogeneity. Modest influence of each study was observed on overall estimate in sensitive analysis, and evident tendency to significant association was seen in cumulative analysis over time, together indicating the robust stability of the current results

CD40LG and GZMB were correlated with adipose tissue macrophage infiltration and involved in obstructive sleep apnea related metabolic dysregulation: Evidence from bioinformatics analysis

Both obesity and obstructive sleep apnea (OSA) can lead to metabolic dysregulation and systemic inflammation. Similar to obesity, increasing evidence has revealed that immune infiltration in the visceral adipose tissue (VAT) is associated with obstructive sleep apnea-related morbidity. However, the pathological changes and potential molecular mechanisms in visceral adipose tissue of obstructive sleep apnea patients need to be further studied. Herein, by bioinformatics analysis and clinical validation methods, including the immune-related differentially expressed genes (IRDEGs) analysis, protein-protein interaction network (PPI), functional enrichment analysis, a devolution algorithm (CIBERSORT), spearman’s correlation analysis, polymerase chain reaction (PCR), Enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry (IHC), we identified and validated 10 hub IRDEGs, the relative mRNA expression of four hub genes (CRP, CD40LG, CCL20, and GZMB), and the protein expression level of two hub genes (CD40LG and GZMB) were consistent with the bioinformatics analysis results. Immune infiltration results further revealed that obstructive sleep apnea patients contained a higher proportion of pro-inflammatory M1 macrophages and a lower proportion of M2 macrophages. Spearman’s correlation analysis showed that CD40LG was positively correlated with M1 macrophages and GZMB was negatively correlated with M2 macrophages. CD40LG and GZMB might play a vital role in the visceral adipose tissue homeostasis of obstructive sleep apnea patients. Their interaction with macrophages and involved pathways not only provides new insights for understanding molecular mechanisms but also be of great significance in discovering novel small molecules or other promising candidates as immunotherapies of OSA-associated metabolic complications

A Fiber Bragg Grating Sensing Structure for the Design, Simulation and Stress Strain Monitoring of Human Puncture Surgery

In order to improve the precision and stability of puncture surgical operations to assist doctors in completing fine manipulation, a new of type puncturing needle sensor is proposed based on a fiber Bragg grating (FBG). Compared with the traditional puncture needle sensor, the new type of puncturing needle sensor is able to sense not only the axial force, but also the torque force during the puncture process. A spoke-type structure is designed near the needle tip. In order to eliminate the influence of temperature and realize temperature compensation, a reference fiber method using three FBGs is applied. FBG1 and the reference FBG2 are pasted on the upper and lower surfaces of the new-type elastic beam, and FBG3 is pasted into the groove on the surface of the new type of puncturing needle cylinder. The difference of Bragg wavelength between FBG1 and the reference FBG2 is calibrated with the torque force, while the difference between the Bragg wavelength of the FBG3 and the reference FBG2 is calibrated with the axial force. Through simulation and sensing tests, when the torque force calibration range is 10 mN·m, the torque average sensitivity is 22.8 pm/mN·m, and the determination coefficient R2 is 0.99992, with a hysteresis error YH and repetition error YR of 0.03%FS and 0.81%FS, respectively. When the axial force calibration rang is 5 N, the axial force average sensitivity is 0.089 nm/N, and the determination coefficient R2 is 0.9997, with hysteresis error YH and repetition error YR of 0.014%FS and 0.11%FS, respectively. The axial force resolution and torque resolution of the new type of puncturing needle sensor are 0.03 N and 0.8 mN·m, respectively. The experimental data and simulation analysis show that the proposed new type of puncturing needle sensor has good practicability and versatility