Consistent deformations method applied to a topological coupling of antisymmetric gauge fields in D=3

In this work we use the method of consistent deformations of the master equation by Barnich and Henneaux in order to prove that an abelian topological coupling between a zero and a two form fields in D=3 has no nonabelian generalization. We conclude that a topologically massive model involving the Kalb-Ramond two-form field does not admit a nonabelian generalization. The introduction of a connection-type one form field keeps the previous result.Comment: 8 pages. To appear in Physics Letters

Timing of complications and length of stay after rectal cancer surgery.

BACKGROUND: Enhanced recovery pathways have been shown to improve short-term outcomes after colorectal surgery. Occurrence of complications can lead to prolonged length of stay (LOS). The goal of this study was to examine whether shorter time to occurrence of complications was associated with a shorter hospital LOS in rectal cancer patients undergoing minimally invasive surgery, taking into account the perioperative pathway. STUDY DESIGN: This retrospective study included consecutive patients undergoing rectal cancer resection from 2005 to 2011 at a single institution. Enhanced recovery pathway was introduced in 2009. Complications and date of occurrence were reviewed. The impact of perioperative care modalities and comorbidities was evaluated using competing risk models with occurrence of complications and LOS as time-dependent outcomes measured as time from surgery. RESULTS: A total of 346 patients were included in the analysis with 78 patients treated with enhanced recovery pathway, and 268 with established care. The overall complication rate was 22.3% (77 patients with ileus, wound infection, leak, abscess, small bowel obstruction, reoperation for bleeding, and renal failure). Median time to occurrence of a complication was 3 days post operation. The time to complication diagnosis was associated with shorter time to discharge after the advent of the complication (hazard ratio = 0.84; 95% CI, 0.73-0.96; p = 0.01). Enhanced recovery pathway was associated with a shorter LOS for patients without complications compared with the established pathway (hazard ratio = 2.81; 95% CI, 2.09-3.78; p < 0.001) after adjusting for comorbidities in a competing risk model. CONCLUSIONS: Early diagnosis of postoperative complications is associated with a shorter LOS after rectal cancer surgery. Enhanced recovery pathway can facilitate a faster recovery in the presence of comorbidities

Challenges of Modeling Outcomes for Surgical Infections: A Word of Caution.

Background: We developed a novel analytic tool for colorectal deep organ/space surgical site infections (C-OSI) prediction utilizing both institutional and extra-institutional American College of Surgeons-National Surgical Quality Improvement Program (ACS-NSQIP) data. Methods: Elective colorectal resections (2006-2014) were included. The primary end point was C-OSI rate. A Bayesian-Probit regression model with multiple imputation (BPMI) via Dirichlet process handled missing data. The baseline model for comparison was a multivariable logistic regression model (generalized linear model; GLM) with indicator parameters for missing data and stepwise variable selection. Out-of-sample performance was evaluated with receiver operating characteristic (ROC) analysis of 10-fold cross-validated samples. Results: Among 2,376 resections, C-OSI rate was 4.6% (n = 108). The BPMI model identified (n = 57; 56% sensitivity) of these patients, when set at a threshold leading to 80% specificity (approximately a 20% false alarm rate). The BPMI model produced an area under the curve (AUC) = 0.78 via 10-fold cross- validation demonstrating high predictive accuracy. In contrast, the traditional GLM approach produced an AUC = 0.71 and a corresponding sensitivity of 0.47 at 80% specificity, both of which were statstically significant differences. In addition, when the model was built utilizing extra-institutional data via inclusion of all (non-Mayo Clinic) patients in ACS-NSQIP, C-OSI prediction was less accurate with AUC = 0.74 and sensitivity of 0.47 (i.e., a 19% relative performance decrease) when applied to patients at our institution. Conclusions: Although the statistical methodology associated with the BPMI model provides advantages over conventional handling of missing data, the tool should be built with data specific to the individual institution to optimize performance