Using the Wigner-Ibach Surmise to Analyze Terrace-Width Distributions: History, User's Guide, and Advances

A history is given of the applications of the simple expression generalized from the surmise by Wigner and also by Ibach to extract the strength of the interaction between steps on a vicinal surface, via the terrace width distribution (TWD). A concise guide for use with experiments and a summary of some recent extensions are provided.Comment: 11 pages, 4 figures, reformatted (with revtex) version of refereed paper for special issue of Applied Physics A entitled "From Surface Science to Device Physics", in honor of the retirements of Prof. H. Ibach and Prof. H. L\"ut

Effect of understaging on local recurrence of rectal cancer

Background and Objectives: Magnetic resonance imaging of the pelvis has a limited accuracy to detect positive lymph nodes but does dictate neoadjuvant treatment in rectal cancer. This study aimed to investigate preoperative lymph node understaging and its effects on postoperative local recurrence rate. Methods: Patients were selected from a retrospective cross-sectional snapshot study. Patients with emergency surgery, cM1 disease, or unknown cN- or (y)pN category were excluded. Clinical and pathologic N-categories were compared and the impact on local recurrence was determined by multivariable analysis. Results: Out of 1548 included patients, 233 had preoperatively underestimated lymph node staging based on (y)pN category. Out of the 695 patients staged cN0, 168 (24%) had positive lymph nodes at pathology, and out of the 594 patients staged cN1, 65 (11%) were (y)pN2. Overall 3-year local recurrence rate was 5%. Clinical N-category was not associated with local recurrence when corrected for pT-category, neoadjuvant therapy, and resection margin, neither in patients with (y)pN1 (hazard ratio [HR]: 1.67 (95% confidence interval [CI]: 0.68-4.12) P =.263) nor (y)pN2-category (HR: 1.91 95% CI: [0.75-4.84], P =.175). Conclusion: Preoperative understaging of nodal status in rectal cancer is not uncommon. No significant effect on local recurrence or overall survival rates were found in the present study

Postoperative antibiotics and time to reach discharge criteria after appendectomy for complex appendicitis

IntroductionPostoperative antibiotic treatment is indicated for 3 - 5 days following appendectomy for complex appendicitis. However, meeting discharge criteria may allow for safe discontinuation of antibiotics and discharge. This study assessed the association between time to reach discharge criteria and duration of postoperative antibiotic use and length of stay. MethodsThis is a multicenter retrospective cohort study including patients who underwent appendectomy for complex appendicitis and received postoperative antibiotics for >24 hours. Main outcome measures were time to reach discharge criteria, duration of postoperative antibiotic use, length of hospital stay and postoperative infectious complications. Discharge criteria were defined as absence of fever (temperatur

Non-Cross-Linked Collagen Mesh Performs Best in a Physiologic, Noncontaminated Rat Model

Background. In laparoscopic incisional hernia repair, direct contact between the prosthesis and abdominal viscera is inevitable and may lead to adhesions. Despite the large variety of mesh prosthesis, little is known about their in vivo behavior. Biological meshes are considered to have many advantages, but due to their price they are rarely used. A rat model was used to assess biological and conventional synthetic meshes on their in vivo characteristics. Design. One-hundred twenty male Wistar rats were randomized into five groups of 24 rats. A mesh was implanted intraperitoneally and fixated with nonresorbable sutures. The following five meshes were implanted: Parietene (polypropylene), Permacol (cross-linked porcine acellular dermal matrix), Strattice (non-cross-linked porcine acellular dermal matrix), XCM Biologic (non-cross-linked porcine acellular dermal matrix), and Omyra Mesh (condensed polytetrafluoroethylene). The rats were sacrificed after 30, 90, or 180 days. Incorporation, shrinkage, adhesions, abscess formation, and histology were assessed for all meshes. Results. All animals thrived postoperatively. After 180 days, Permacol, Parietene, and Omyra Mesh had a significantly better incorporation than Strattice (P =.001, P =.019, and P =.037 respectively). After 180 days, Strattice had significantly fewer adhesions on the surface of the mesh than Parietene (P <.001), Omyra Mesh (P =.011), and Permacol (P =.027). After 30 days, Permacol had significantly stronger adhesions than Strattice (P =.030). However, this difference was not significant anymore after 180 days. After 180 days, there was significantly less shrinkage in Permacol than in Strattice (P =.001) and Omyra Mesh (P =.050). Conclusion. Based on incorporation, adhesions, mesh shrinkage, and histologic parameters, Strattice performed best in this experimental rat model