The anisotropic quantum antiferromagnet on the Sierpinski gasket: Ground state and thermodynamics

We investigate an antiferromagnetic s=1/2 quantum spin system with anisotropic spin exchange on a fractal lattice, the Sierpinski gasket. We introduce a novel approximative numerical method, the configuration selective diagonalization (CSD) and apply this method to the Sierpinski gasket with N=42. Using this and other methods we calculate ground state energies, spin gap, spin-spin correlations and specific heat data and conclude that the s=1/2 quantum antiferromagnet on the Sierpinski gasket shows a disordered magnetic ground state with a very short correlation length of about 1 and an, albeit very small, spin gap. This conclusion holds for Heisenberg as well a for XY exchange.Comment: LaTeX: 16 pages, 9 figures, 1 tabl

Transanal endoscopic microsurgery combined with endoscopic posterior mesorectum resection in the treatment of patients with T1 rectal cancer : 3-year results

INTRODUCTION: Rectum-sparing transanal endoscopic microsurgery (TEM) is a well-established treatment for T1 rectal cancer (RC). However, it is associated with an increased rate of local recurrence in comparison with extended resection. In most cases this failure is linked to inappropriate case selection and the presence of clinically non-detectable metastases in the regional lymph nodes. Endoscopic posterior mesorectal resection (EPMR) makes it possible to remove the relevant lymphatic drainage of the lower third of the rectum in a minimally invasive way, which in turn can help in adequate tumor staging. AIM: To evaluate the long-term clinical results and influence of combined TEM and EPMR treatment on the anorectal functions. MATERIAL AND METHODS: Ten consecutive patients with T1 RC were operated on using TEM and EPMR as a two-stage procedure between 2007 and 2009. RESULTS: After a median follow-up of 42.6 (range: 36–80) months, none of our patients complained of symptoms of incontinence apart from one female patient with gas incontinence diagnosed preoperatively. There was no statistically significant difference in basal anal pressure, squeeze anal pressure, high pressure zone length or fecal continence assessed using the Fecal Incontinence Severity Index before and in follow-up months after the procedure. Postoperative morbidity consisted of one hematoma formation and one male patient complaining about sexual dysfunction until 6 months postoperatively. There was no evidence of locoregional recurrence. CONCLUSIONS: Endoscopic posterior mesorectal resection in combination with TEM appears to be safe, feasible and with no impact on the basic anorectal functions in the 3-year follow-up

Low-lying excitations and thermodynamics of an antiferromagnetic Heisenberg fractal system of a dimension between one and two

We investigate a frustrated Heisenberg spin-1/2 antiferromagnet on a fractal lattice of dimension d=ln3/ln2 (Sierpinski gasket). Calculations were performed using (a) exact diagonalization of all eigenstates and eigenvectors for systems up to N=15 and (b) the Decoupled-Cell Quantum-Monte-Carlo method for systems up to N=366. We present the low-lying spectrum and the specific heat. The specific heat shows a second maximum in the low-temperature region. This behavior is similar to the behavior of the quantum Heisenberg antiferromagnet on a kagome lattice and suggests a disordered ground state and a spin gap in the considered system.Comment: 2 pages, LaTeX, 3 eps figures, to appear in JMM

The need for culture swabs in laparoscopically treated appendicitis

INTRODUCTION: Appendicitis remains the most common cause of an acute abdomen. Obtaining intra-abdominal cultures is routine surgical practice. There are studies showing no efficacy of such procedures in cases where open appendectomies are performed. AIM: The goal of this study was to assess the need for obtaining intra-abdominal cultures during laparoscopic appendectomies. MATERIAL AND METHODS: Between 2007 and 2012, 369 patients were operated on with the diagnosis of histopathologically proven acute appendicitis. Sixty-two percent of them were operated on using laparoscopic techniques. The microbiological assessment was routinely done for the open procedures and in 42% of cases that underwent a laparoscopic operation. RESULTS: In 57% (134) the swabbing results were negative. Among 43% (102) of the patients with a positive result, Escherichia coli was isolated in 76.5% (78), Proteus mirabilis in 13.7% (14), Pseudomonas aeruginosa in 4.9% (5) and Citrobacter freundii in 4.9% (5). Five cases had bacteria resistant to the antibiotic given preoperatively (that is 4.9% of all positive cultures and 1.4% of all operated patients). However, these cases did not affect the incidence of postoperative complications. Consideration of the postoperative morbidity showed that there was no statistically significant difference between the laparoscopic group with and without intra-operative swabbing (p > 0.05). CONCLUSIONS: The postoperative patient outcome was more dependent on the pathology of the appendix than on the results of the microbiological assessment at the time of surgery. Hence, routine intra-operative cultures during laparoscopic appendectomies appear to have little value in patient management. Swabbing during laparoscopic procedures should be limited to only selected high-risk groups

Determinants of hypofibrinolysis in patients with digestive tract cancer

Introduction: Recently, we demonstrated that digestive tract cancer (DTC) is associated with reduced fibrin clot permeability and impaired fibrinolysis. Aim: We investigated determinants of fibrinolysis in DTC patients. Material and methods: In 44 consecutive patients with DTC and 47 controls matched for age, sex, and cardiovascular risk, we evaluated fibrinolysis proteins, platelet activation markers, thrombin formation, together with plasma clot lysis time assays in the absence (CLT) and presence of carboxypeptidase potato inhibitor (CLT CPI) that blocks thrombin activatable fibrinolysis inhibitor (TAFI). Results: In the DTC group CLT (by 22.3%) and CLT CPI (by 27.4%) were longer compared with controls. The DTC patients had higher plasma fibrinolysis inhibitors, plasminogen activator inhibitor 1 (PAI-1) (by 18.2%), TAFI activity (by 17.3%), and antigen (by 11.2%). The patients had markedly increased platelet markers - soluble CD40 ligand (by 338%) and P-selectin (by 97%), together with von Willebrand factor (vWF) antigen (by 61%). Thrombin-antithrombin complexes (TAT) (by 48.7%) and soluble thrombomodulin (sTM) (by 17.2%) were also increased in the DTC group (all p < 0.05). Patients with high-grade tumours (n = 26) compared with remainders (n = 18) had longer CLT, higher tissue-type plasminogen activator antigen, both TAFI antigen and activity levels, vWF, and sTM. Multiple regression analysis after adjustment for potential confounders showed that independent predictors of CLT in DTC patients were TAT, TAFI activity, and vWF. The only independent predictor of CLT CPI was TAT. Conclusions: Hypofibrinolysis in DTC patients is largely driven by enhanced thrombin generation, TAFI, and endothelial injur