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The hyperpolarizabilities of conjugated polymers are studied within a tight-binding model. Exact evaluation of y' '(3') is carried out numerically for polymer chains of varying lengths, cispolyacetylene and polythiophene. EA'ects of solitons on y' ' are considered. Among many interesting properties of conjugated polymers, the unusually large optical nonlinearity has received much attention recently. Aside from possible optoelectronic applications, the third-order susceptibility g' ' also provides unique information about the excited states. It is therefore useful to calculate g' ' from theoretical models and to compare it with experiment.Due to mathematical complications not many realistic calculations are available. Model calculations' involving electron-electron interactions have been carried out only for very short chains, whereas the remarkable chain-length dependence of y' ' persists for moderately long chains.Recently, Wu performed a Green's-

SUMMARY BackgroundThe diagnosis of gastro-oesophageal reflux disease (GERD) is based on reflux symptoms. Although metabolic syndrome has been linked to erosive oesophagitis (EO), the impact of insulin resistance, the core of the metabolic syndrome, on reflux symptoms remains to be elucidated.

BackgroundAfter a low anterior resection, creating a defunctioning stoma is vital for securing the anastomosis in low-lying rectal cancer patients receiving concurrent chemoradiotherapy. Although it decreases the complication and reoperation rates associated with anastomotic leakage, the complications that arise before and after stoma closure should be carefully evaluated and managed.MethodsThis study enrolled 95 rectal cancer patients who received neoadjuvant concurrent chemoradiotherapy and low anterior resection with anastomosis of the bowel between July 2010 and November 2012. A defunctioning stoma was created in 63 patients during low anterior resection and in another three patients after anastomotic leakage.ResultsThe total complication rate from stoma creation to closure was 36.4%. Ileostomy led to greater renal insufficiency than colostomy did and significantly increased the readmission rate (all p < 0.05). The complication rate related to stoma closure was 36.0%. Patients with ileostomy had an increased risk of developing complications (p = 0.017), and early closure of the defunctioning stoma yielded a higher incidence of morbidity (p = 0.006). Multivariate analysis revealed that a time to closure of ≤109 days was an independent risk factor for developing complications (p = 0.007).ConclusionsThe optimal timing of stoma reversal is at least 109 days after stoma construction in rectal cancer patients receiving concurrent chemoradiotherapy and low anterior resection.