A nonlinear hydrodynamical approach to granular materials

We propose a nonlinear hydrodynamical model of granular materials. We show how this model describes the formation of a sand pile from a homogeneous distribution of material under gravity, and then discuss a simulation of a rotating sandpile which shows, in qualitative agreement with experiment, a static and dynamic angle of repose.Comment: 17 pages, 14 figures, RevTeX4; minor changes to wording and some additional discussion. Accepted by Phys. Rev.

The Effect of Postoperative Complications After Minimally Invasive Esophagectomy on Long-term Survival: An International Multicenter Cohort Study

BACKGROUND: Esophagectomy is a technically challenging procedure, associated with significant morbidity. The introduction of minimally invasive esophagectomy (MIE) has reduced postoperative morbidity. OBJECTIVE: Although the short-term effect on complications is increasingly being recognized, the impact on long-term survival remains unclear. This study aims to investigate the association between postoperative complications following MIE and long-term survival. METHODS: Data were collected from the EsoBenchmark Collaborative composed by 13 high-volume, expert centers routinely performing MIE. Patients operated between June 1, 2011 and May 31, 2016 were included. Complications were graded using the Clavien-Dindo (CD) classification. To correct for short-term effects of postoperative complications on mortality, patients who died within 90 days postoperative were excluded. Primary endpoint was 5-year overall survival. RESULTS: A total of 915 patients were included with a mean follow-up time of 30.8 months (standard deviation 17.9). Complications occurred in 542 patients (59.2%) of which 50.2% had a CD grade ≥III complication [ie, (re)intervention, organ dysfunction, or death]. The incidence of anastomotic leakage (AL) was 135 of 915 patients (14.8%) of which 84 patients were classified as a CD grade ≥III. Multivariable analysis showed a significantly deteriorated long-term survival in all patients with AL [hazard ratio (HR) 1.68, 95% confidence interval (CI) 1.25-2.24]. This inverse relation was most distinct when AL was scored as a CD grade ≥III (HR 1.83, 95% CI 1.30-2.58). For all other complications, no significant association with long-term survival was found. CONCLUSION: The occurrence and severity of AL, but not overall complications, after MIE negatively affect long-term survival of esophageal cancer patients

Isolation and molecular characterization of Xylella fastidiosa from coffee plants in Costa Rica.

Copyright The Microbiological Society of Korea and Springer-Verlag Berlin Heidelber GmbH 2008. / . Datos incluidos por Lisela Moreira Carmona.Coffee plants exhibiting a range of symptoms including mild to severe curling of leaf margins, chlorosis and deformation of leaves, stunting of plants, shortening of internodes, and dieback of branches have been reported since 1995 in several regions of Costa Rica's Central Valley. The symptoms are referred to by coffee producers in Costa Rica as "crespera" disease and have been associated with the presence of the bacterium Xylella fastidiosa. Coffee plants determined to be infected by the bacterium by enzyme linked immunosorbent assay (ELISA), were used for both transmission electron microscopy (TEM) and for isolation of the bacterium in PW broth or agar. Petioles examined by TEM contained rod-shaped bacteria inside the xylem vessels. The bacteria measured 0.3 to 0.5 μm in width and 1.5 to 3.0 μm in length, and had rippled cell walls 10 to 40 nm in thickness, typical of X. fastidiosa. Small, circular, dome-shaped colonies were observed 7 to 26 days after plating of plant extracts on PW agar. The colonies were comprised of Gram-negative rods of variable length and a characteristic slight longitudinal bending. TEM of the isolated bacteria showed characteristic rippled cell walls, similar to those observed in plant tissue. ELISA and PCR with specific primer pairs 272-l-int/272-2-int and RST31/RST33 confirmed the identity of the isolated bacteria as X. fastidiosa. RFLP analysis of the amplification products revealed diversity within X. fastidiosa strains from Costa Rica and suggest closer genetic proximity to strains from the United States of America than to other coffee or citrus strains from Brazil.Fundación CR-USAUniversidad de Costa Rica/[801-A2-528]/UCR/Costa RicaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Biología Celular y Molecular (CIBCM

Mortality from esophagectomy for esophageal cancer across low, middle, and high-income countries: An international cohort study.

BACKGROUND No evidence currently exists characterising global outcomes following major cancer surgery, including esophageal cancer. Therefore, this study aimed to characterise impact of high income countries (HIC) versus low and middle income countries (LMIC) on the outcomes following esophagectomy for esophageal cancer. METHOD This international multi-center prospective study across 137 hospitals in 41 countries included patients who underwent an esophagectomy for esophageal cancer, with 90-day follow-up. The main explanatory variable was country income, defined according to the World Bank Data classification. The primary outcome was 90-day postoperative mortality, and secondary outcomes were composite leaks (anastomotic leak or conduit necrosis) and major complications (Clavien-Dindo Grade III - V). Multivariable generalized estimating equation models were used to produce adjusted odds ratios (ORs) and 95% confidence intervals (CI). RESULTS Between April 2018 to December 2018, 2247 patients were included. Patients from HIC were more significantly older, with higher ASA grade, and more advanced tumors. Patients from LMIC had almost three-fold increase in 90-day mortality, compared to HIC (9.4% vs 3.7%, p < 0.001). On adjusted analysis, LMIC were independently associated with higher 90-day mortality (OR: 2.31, CI: 1.17-4.55, p = 0.015). However, LMIC were not independently associated with higher rates of anastomotic leaks (OR: 1.06, CI: 0.57-1.99, p = 0.9) or major complications (OR: 0.85, CI: 0.54-1.32, p = 0.5), compared to HIC. CONCLUSION Resections in LMIC were independently associated with higher 90-day postoperative mortality, likely reflecting a failure to rescue of these patients following esophagectomy, despite similar composite anastomotic leaks and major complication rates to HIC. These findings warrant further research, to identify potential issues and solutions to improve global outcomes following esophagectomy for cancer