Long-term risk of gastric cancer by subsite in operated and unoperated patients hospitalized for peptic ulcer

OBJECTIVE: We aimed to investigate whether the elevated risk of gastric cancer among patients with gastric ulcer (GU) and the enigmatic low risk among patients with duodenal ulcer (DU) pertain to both cardia and noncardia cancer. We also studied the risks among operated patients while taking the disparate baseline risks into consideration. METHODS: Retrospective cohorts of 59,550 and 79,412 unoperated patients with DU and GU, respectively, plus 12,840 patients with partial gastric resection and 8,105 with vagotomy, recorded in the Swedish Inpatient Register since 1970, were followed from the first hospitalization (date of operation for the surgery cohort) until occurrence of any cancer, death, emigration, definitive surgery, or December 31, 2003. Standardized incidence ratios (SIRs) with 95% confidence intervals (CIs) expressed relative risk (RR), compared to the age-, sex-, and calendar period-matched Swedish population. Cox regression produced adjusted RR estimates among operated patients, relative to unoperated ones with the same ulcer type. RESULTS: While unoperated DU patients had a halved risk of noncardia cancer (SIR = 0.5, 95% CI 0.4-0.7), their risk of cardia cancer was slightly above expectation (SIR = 1.2, 95% CI 0.8-1.7). Unoperated GU patients had doubled risks for both cancers (SIR = 2.1, 95% CI 2.0-2.4 and SIR = 1.9, 95% CI 1.4-2.3, respectively). DU patients who underwent gastric resection had a 60% risk elevation (RR = 1.6, 95% CI 1.0-2.5) compared to unoperated ones. Vagotomy was associated with a greater risk in the first 10 yr, but this excess disappeared with further follow-up. Resected GU patients had a 40% risk reduction relative to their unoperated peers (RR = 0.6, 95% CI 0.5-0.8). This reduction persisted well beyond the first postoperative decade. CONCLUSION: The DU-related protection against gastric cancer does not seem to pertain to cardia cancer. With gastric resection, risks are shifted toward normality, regardless of underlying ulcer type. © 2007 by Am. Coll. of Gastroenterology

Entropy of chains placed on the square lattice

We obtain the entropy of flexible linear chains composed of M monomers placed on the square lattice using a transfer matrix approach. An excluded volume interaction is included by considering the chains to be self-and mutually avoiding, and a fraction rho of the sites are occupied by monomers. We solve the problem exactly on stripes of increasing width m and then extrapolate our results to the two-dimensional limit to infinity using finite-size scaling. The extrapolated results for several finite values of M and in the polymer limit M to infinity for the cases where all lattice sites are occupied (rho=1) and for the partially filled case rho<1 are compared with earlier results. These results are exact for dimers (M=2) and full occupation (\rho=1) and derived from series expansions, mean-field like approximations, and transfer matrix calculations for some other cases. For small values of M, as well as for the polymer limit M to infinity, rather precise estimates of the entropy are obtained.Comment: 6 pages, 7 figure

Stripes and holes in a two-dimensional model of spinless fermions and hardcore bosons

We consider a Hubbard-like model of strongly-interacting spinless fermions and hardcore bosons on a square lattice, such that nearest neighbor occupation is forbidden. Stripes (lines of holes across the lattice forming antiphase walls between ordered domains) are a favorable way to dope this system below half-filling. The problem of a single stripe can be mapped to a spin-1/2 chain, which allows understanding of its elementary excitations and calculation of the stripe's effective mass for transverse vibrations. Using Lanczos exact diagonalization, we investigate the excitation gap and dispersion of a hole on a stripe, and the interaction of two holes. We also study the interaction of two, three, and four stripes, finding that they repel, and the interaction energy decays with stripe separation as if they are hardcore particles moving in one (transverse) direction. To determine the stability of an array of stripes against phase separation into particle-rich phase and hole-rich liquid, we evaluate the liquid's equation of state, finding the stripe-array is not stable for bosons but is possibly stable for fermions.Comment: 24 pages, 18 figure

25 Years of Self-organized Criticality: Concepts and Controversies

Introduced by the late Per Bak and his colleagues, self-organized criticality (SOC) has been one of the most stimulating concepts to come out of statistical mechanics and condensed matter theory in the last few decades, and has played a significant role in the development of complexity science. SOC, and more generally fractals and power laws, have attracted much comment, ranging from the very positive to the polemical. The other papers (Aschwanden et al. in Space Sci. Rev., 2014, this issue; McAteer et al. in Space Sci. Rev., 2015, this issue; Sharma et al. in Space Sci. Rev. 2015, in preparation) in this special issue showcase the considerable body of observations in solar, magnetospheric and fusion plasma inspired by the SOC idea, and expose the fertile role the new paradigm has played in approaches to modeling and understanding multiscale plasma instabilities. This very broad impact, and the necessary process of adapting a scientific hypothesis to the conditions of a given physical system, has meant that SOC as studied in these fields has sometimes differed significantly from the definition originally given by its creators. In Bak’s own field of theoretical physics there are significant observational and theoretical open questions, even 25 years on (Pruessner 2012). One aim of the present review is to address the dichotomy between the great reception SOC has received in some areas, and its shortcomings, as they became manifest in the controversies it triggered. Our article tries to clear up what we think are misunderstandings of SOC in fields more remote from its origins in statistical mechanics, condensed matter and dynamical systems by revisiting Bak, Tang and Wiesenfeld’s original papers

To boldly go where no scope has gone before: towards an in-vivo grid

No abstract available

Conditional Survival and Cure of Patients With Colon or Rectal Cancer: A Population-Based Study

Contains fulltext : 225975.pdf (Publisher’s version ) (Closed access)BACKGROUND: The increasing number of colorectal cancer (CRC) survivors need survival estimates that account for the time already survived. The aim of this population-based study was to determine conditional survival, cure proportions, and time-to-cure (TTC) of patients with colon or rectal cancer. MATERIALS AND METHODS: All patients with pathologic stage I-III CRC treated with endoscopy or surgery, diagnosed and registered in the Netherlands Cancer Registry between 1995 and 2016, and aged 18 to 99 years were included. Conditional survival was calculated for those diagnosed before and after 2007. Cure proportions were calculated using flexible parametric models. RESULTS: A total of 175,384 patients with pathologic stage I (25%), II (38%), or III disease (37%) were included. Conditional 5-year survival of patients with stage I, II, and III colon cancer having survived 5 years was 98%, 94%, and 92%, respectively. For patients with stage I-III rectal cancer, this was 96%, 89%, and 85%, respectively. Statistical cure in patients with colon cancer was reached directly after diagnosis (stage I) to 6 years (stage III) after diagnosis depending on age, sex, and disease stage. Patients with rectal cancer reached cure 0.5 years after diagnosis (stage I) to 9 years after diagnosis (stage III). In 1995, approximately 42% to 46% of patients with stage III colon or rectal cancer, respectively, were considered cured, whereas in 2016 this percentage increased to 73% to 78%, respectively. CONCLUSIONS: The number of patients with CRC reaching cure has increased substantially over the years. This study's results provide valuable insights into trends of CRC patient survival and are important for patients, clinicians, and policymakers

Risk of gastroesophageal cancer among smokers and users of Scandinavian moist snuff

Although Scandinavian moist snuff ("snus"), no doubt, is a safer alternative to smoking, there is limited evidence against an association with gastroesophageal cancers. In a retrospective cohort study, we investigated esophageal and stomach cancer incidence among 336,381 male Swedish construction workers who provided information on tobacco smoking and snus habits within a health surveillance program between 1971 and 1993. Essentially complete follow-up through 2004 was accomplished through linkage to several nationwide registers. Multivariable Cox proportional hazards regression models estimated relative risks (RR) and 95% confidence intervals (CIs). Compared to never-users of any tobacco, smokers had increased risks for adenocarcinoma (RR = 2.3, 95% CI 1.4-3.7) and squamous cell carcinoma (RR = 5.2, 95% CI 3.1-8.6) of the esophagus, as well as cardia (RR = 2.1, 95% CI 1.5-3.0) and noncardia stomach (RR = 1.3, 95% CI 1.2-1.6) cancers. We also observed excess risks for esophageal squamous cell carcinoma (RR = 3.5, 95% CI 1.6-7.6) and noncardia stomach cancer (RR = 1.4, 95% CI 1.1-1.9) among snus users who had never smoked. Although confounding by unmeasured exposures, and some differential misclassification of smoking, might have inflated the associations, our study provides suggestive evidence for an independent carcinogenic effect of snus. \ua9 2007 Wiley-Liss, Inc