IMPROVED RESULTS ON THE ROBUSTNESS OF STOCHASTIC APPROXIMATION ALGORITHMS

This paper is a continuation of the research carried out in [1]-[2], where the robustnessanalysis for stochastic approximation algorithms is given for two cases: 1. The regression functionand the Liapunov function are not zero at the sought-for x^0, 2. lim supnot zero, here {ξ_i} are the measurement errors and {a_n} are the weighting coefficients in thealgorithm. Allowing these deviations from zero to occur simultaneously but to remain small, thispaper shows that the estimation error is still small even for a class fo measurement errors moregeneral than that considered in [2].

National trends in resection of the distal pancreas

AIM:To investigate national trends in distal pancreatectomy(DP) through query of three national patient care databases.METHODS:From the Nationwide Inpatient Sample(NIS,2003-2009),the National Surgical Quality Improvement Project(NSQIP,2005-2010),and the Surveillance Epidemiology and End Results(SEER,2003-2009) databases using appropriate diagnostic and procedural codes we identified all patients with a diagnosis of a benign or malignant lesion of the body and/or tail of the pancreas that had undergone a partial or distal pancreatectomy.Utilization of laparoscopy was defined in NIS by the International Classification of Diseases,Ninth Revision correspondent procedure code;and in NSQIP by the exploratory laparoscopy or unlisted procedure current procedural terminology codes.In SEER,patients were identified by the International Classification of Diseases for Oncology,Third Edition diagnosis codes and the SEER Program Code Manual,third edition procedure codes.We analyzed the databases with respect to trends of inpatient outcome metrics,oncologic outcomes,and hospital volumes in patients with lesions of the neck and body of the pancreas that underwent operative resection.RESULTS:NIS,NSQIP and SEER identified 4242,2681 and 11 082 DP resections,respectively.Overall,laparoscopy was utilized in 15%(NIS) and 27%(NSQIP).No significant increase was seen over the course of the study.Resection was performed for malignancy in 59%(NIS) and 66%(NSQIP).Neither patient Body mass index nor comorbidities were associated with operative approach(P = 0.95 and P = 0.96,respectively).Mortality(3% vs 2%,P = 0.05) and reoperation(4% vs 4%,P = 1.0) was not different between laparoscopy and open groups.Overall complications(10% vs 15%,P < 0.001),hospital costs [44 741 dollars,interquartile range(IQR) 28 347-74 114 dollars vs 49 792 dollars,IQR 13 299-73 463,P = 0.02] and hospital length of stay(7 d,IQR 4-11 d vs 7 d,IQR 6-10,P < 0.001) were less when laparoscopy was utilized.One and two year survival after resection for malignancy were unchanged over the course of the study(ductal adenocarinoma 1-year 63.6% and 2-year 35.1%,P = 0.53;intraductal papillary mucinous neoplasm and nueroendocrine 1-year 90% and 2-year 84%,P = 0.25).The majority of resections were performed in teaching hospitals(77% NIS and 85% NSQIP),but minimally invasive surgery(MIS) was not more likely to be used in teaching hospitals(15% vs 14%,P = 0.26).Hospitals in the top decile for volume were more likely to be teaching hospitals than lower volume deciles(88% vs 43%,P < 0.001),but were no more likely to utilize MIS at resection.Complication rate in teaching and the top decile hospitals was not significantly decreased when compared to non-teaching(15% vs 14%,P = 0.72) and lower volume hospitals(14% vs 15%,P = 0.99).No difference was seen in the median number of lymph nodes and lymph node ratio in N1 disease when compared by year(P = 0.17 and P = 0.96,respectively).CONCLUSION:There appears to be an overall underutilization of laparoscopy for DP.Centralization does not appear to be occurring.Survival and lymph node harvest have not changed.