Skeletal CH3OH/NOx Kinetic Model for Simulating Spark-Ignition and Turbulent Jet Ignition Engines.

Methanol is a promising renewable fuel for achieving a better engine combustion efficiency and lower exhaust emissions. Under exhaust gas recirculation conditions, trace amounts of nitrogen oxides have been shown to participate in fuel oxidation and impact the ignition characteristics significantly. Despite numerous studies that analyzed the methanol/NOx interaction, no reliable skeletal kinetic mechanism is available for computational fluid dynamics (CFD) modeling. This work focuses on developing a skeletal CH3OH/NOx kinetic model consisting of 25 species and 55 irreversible and 27 reversible reactions, used for full-cycle engine combustion simulations. New experiments of methanol with the presence of 200 ppmv NO/NO2 were conducted in a rapid compression machine (RCM) at engine-relevant conditions (20-30 bar, 850-950 K). Experimental results indicate notable enhancement effects of the presence of NO/NO2 on methanol ignition under the conditions tested, which highlights the importance of including the CH3OH/NOx interactions in predicting combustion performance. The proposed skeletal mechanism was validated against the literature and new methanol and methanol/NOx experiments over a wide range of operating conditions. Furthermore, the skeletal mechanism was applied in three-dimensional (3D) CFD full-cycle simulations of spark-ignition (SI) and turbulent jet ignition (TJI) engine combustion using methanol. Simulation results demonstrate good agreement with experimental measurements of pressure traces and engine metrics, proving that the proposed skeletal mechanism is suitable and sufficient for CFD simulations.

Improving the Power of the American Society of Anesthesiology Classification System to Risk Stratify Vascular Surgery Patients Based on National Surgical Quality Improvement Project-Defined Functional Status.

BACKGROUND: Recently published reports have shown that the American Society of Anesthesiology (ASA) classification system has limited applicability in vascular surgery patients. Most patients undergoing vascular procedures are designated as ASA class III, limiting discrimination in preoperative risk assessment. The 2006 National Surgical Quality Improvement Project (NSQIP), containing over 170,000 surgical cases, demonstrated that functional status is an important predictor of mortality. We propose that dividing ASA class III into 2 subgroups, based on NSQIP-defined functional status, improves the predictive value of the ASA scheme. METHODS: The 2006 NSQIP database was queried for ASA class III patients undergoing vascular surgery procedures. Patients were divided into groups IIIA and IIIB based on independent or dependent (partial or complete) functional status, respectively. Difference in 30-day survival between subgroups was evaluated using Kaplan-Meier and logistic regression analyses. Differences in postoperative morbidity and length of stay were compared using the unpaired t-test. RESULTS: ASA class III patients having undergone vascular surgery procedures numbered 11,555 (68%). Of those 9,913 (85.7%) patients were independent (IIIA), and 1,642 (14.3%) were dependent (IIIB). Mean 30-day mortality was 1.3% in subgroup IIIA, and 6.5% in IIIB (logrank P < 0.001, χ2, 137.8). Mean lengths of stay between subgroups IIIA and IIIB were 5.4 and 13.2 days (P < 0.001). The risk of NSQIP-defined postoperative complications was 0.16 in IIIA and 0.32 in IIIB (P < 0.001). CONCLUSIONS: A 5-fold difference in mortality was observed between patients who were functionally independent and dependent. A significant increase in length of stay and incidence of postoperative complications was also observed in subgroup IIIB. Subdividing ASA class III vascular surgery patients markedly improves the value of the ASA classification system. Given the "high-risk" nature of patients with vascular disease, the addition of functional status to the preoperative assessment will assist in predicting outcomes in this patient population.

Race and the molecular origins of breast cancer in Chinese women: breast cancer in Chinese women.

Although there is considerable controversy regarding the role of race in the etiology of human disease, evidence suggests that breast cancers are racially distinct diseases. Clinical features and genetic alterations are different in Chinese women with breast cancer compared with white women. These differences are significant and may influence clinical care. In this review, we summarize the literature addressing genetic heterogeneity in Chinese women with breast cancer. Data support important variations in genes involved in tumorigenic pathways of DNA repair, steroid synthesis and receptor expression, apoptosis, immunity, inflammation, cell cycle control, cancer growth and metastasis, and growth receptor signaling. These genetic differences contribute to our understanding of the molecular origins of breast cancer and may accelerate the development of personalized disease prevention strategies.

Extended focused assessment with sonography for trauma (EFAST) in the diagnosis of pneumothorax: experience at a community based level I trauma center.

INTRODUCTION: Early identification of pneumothorax is crucial to reduce the mortality in critically injured patients. The objective of our study is to investigate the utility of surgeon performed extended focused assessment with sonography for trauma (EFAST) in the diagnosis of pneumothorax. METHODS: We prospectively analysed 204 trauma patients in our level I trauma center over a period of 12 (06/2007-05/2008) months in whom EFAST was performed. The patients' demographics, type of injury, clinical examination findings (decreased air entry), CXR, EFAST and CT scan findings were entered into the data base. Sensitivity, specificity, positive (PPV) and negative predictive values (NPV) were calculated. RESULTS: Of 204 patients (mean age--43.01+/-19.5 years, sex--male 152, female 52) 21 (10.3%) patients had pneumothorax. Of 21 patients who had pneumothorax 12 were due to blunt trauma and 9 were due to penetrating trauma. The diagnosis of pneumothorax in 204 patients demonstrated the following: clinical examination was positive in 17 patients (true positive in 13/21, 62%; 4 were false positive and 8 were false negative), CXR was positive in 16 (true positive in 15/19, 79%; 1 false positive, 4 missed and 2 CXR not performed before chest tube) patients and EFAST was positive in 21 patients (20 were true positive [95.2%], 1 false positive and 1 false negative). In diagnosing pneumothorax EFAST has significantly higher sensitivity compared to the CXR (P=0.02). CONCLUSIONS: Surgeon performed trauma room extended FAST is simple and has higher sensitivity compared to the chest X-ray and clinical examination in detecting pneumothorax.

Esophageal perforation after gastric balloon extraction.

We report a case of a 59-year-old female with esophageal perforation following endoscopic removal of an intragastric balloon. To our knowledge, this is the first case of esophageal perforation associated with intragastric balloon extraction reported in the English literature.

Surrounded by quality metrics: what do surgeons think of ACS-NSQIP?

BACKGROUND: In an era of proliferating systems of quality assessment, surgeon confidence in metric tools is essential for successful initiatives in quality improvement. We evaluated surgeons' awareness and attitudes about ACS-NSQIP, which is the only national, surgeon-developed, risk-adjusted, system of surgical outcome assessment. METHODS: A 33-item survey instrument was constructed and content validity established through content expert review; test-retest reliability was assessed (weighted-kappa = 0.72). Survey administration occurred in three institutions with varying ACS-NSQIP experience. Summary statistics were generated and subgroup analyses performed (Fisher's exact test). RESULTS: One-hundred and eight surgeons participated. Practice experience varied (27% residents, 33% < 10, 12% 10-20, and 28% > 20 years). Seventy-two percent had fellowship training. Surgeons were familiar with ACS-NSQIP structure, including prospective data collection (70%), case-sampling (63%), and reporting as observed/expected ratios (83%). Surgeons knew some collected data-points but misidentified EKG-findings of MI (67%), surgeon case-experience (41%), and anastomotic dehiscence (79%). Most felt ACS-NSQIP would improve quality of care (79%) and identify areas for improvement (92%). Surgeons were less confident regarding utility at an individual level, with only 46% believing surgeon-specific outcomes should be reported. Few thought ACS-NSQIP data should be available publicly (45%), used for marketing (26%), or direct pay-for-performance (24%). Reservations were most pronounced among surgeons with institutional ACS-NSQIP experience. CONCLUSION: While surgeons accept ACS-NSQIP at an institutional level, skepticism remains surrounding measurement of individual outcomes and public reporting. Surgeons at institutions with a longer duration of experience with ACS-NSQIP tended to be more cynical about potential data applications. Ongoing education and assessment of surgeons' perceptions of quality improvement initiatives is necessary to ensure surgeons remain engaged actively in determining how quality of care data is measured and utilized.

Solitary fibrous tumor of the parapharyngeal space.

Solitary fibrous tumors are benign neoplasms of mesenchymal origin. They usually arise from the visceral or parietal pleura and peritoneum, although they have been found in many areas throughout the body. We report a case of solitary fibrous tumor of the parapharyngeal space. Microscopically, the tumor contained spindle cells with areas of marked hypercellularity without a definitepattern. Consistent with a benign lesion, there were few mitoses and no necrosis. The tumor cells stained strongly positive for CD34 and vimentin. At the 2-year follow-up, the patient was well and free of local and/or distant disease.

Model for teaching laparoscopic colectomy to surgical residents.

BACKGROUND: This study was undertaken to determine the impact that a resident teaching model for advanced laparoscopic skills has on performance, using outcome for laparoscopic colectomy as an indicator of efficacy. METHODS: Six senior surgical residents took part in a model for teaching advanced laparoscopic procedures over 3 years. Animal laboratory sessions, tutorial sessions, and feedback were the principle components of this model with residents evaluating each component and their operative experiences. Conversion rates, hospital length of stay, and operating time during the 3 years (n = 100) were compared with a previous year (baseline year) where the faculty performed most of a procedure (n = 20). RESULTS: Each resident performed an average of 17 cases, being the primary surgeon after the sixth case. There were no differences in operative time for both right and left colectomies compared with the baseline year. Postoperative length of stay was less than 5 days by year 3, with a 14% conversion rate to open surgery. Feedback and tutorials were deemed most important for strategic planning and for reducing operative time. CONCLUSIONS: Resident participation in advanced laparoscopic surgery, concurrent with structured skills development and feedback, portends very favorable outcomes.