Magnetic field dependence of charge stripe order in La2-xBaxCuO4 (x~1/8)

We have carried out a detailed investigation of the magnetic field dependence of charge ordering in La2-xBaxCuO4 (x~1/8) utilizing high-resolution x-ray scattering. We find that the charge order correlation length increases as the magnetic field greater than ~5T is applied in the superconducting phase (T=2K). The observed unusual field dependence of the charge order correlation length suggests that the static charge stripe order competes with the superconducting ground state in this sample.Comment: 4 pages, 4 figure

Selective and Genetic Constraints on Pneumococcal Serotype Switching

Streptococcus pneumoniae isolates typically express one of over 90 immunologically distinguishable polysaccharide capsules (serotypes), which can be classified into “serogroups” based on cross-reactivity with certain antibodies. Pneumococci can alter their serotype through recombinations affecting the capsule polysaccharide synthesis (cps) locus. Twenty such “serotype switching” events were fully characterised using a collection of 616 whole genome sequences from systematic surveys of pneumococcal carriage. Eleven of these were within-serogroup switches, representing a highly significant (p < 0.0001) enrichment based on the observed serotype distribution. Whereas the recombinations resulting in between-serogroup switches all spanned the entire cps locus, some of those that caused within-serogroup switches did not. However, higher rates of within-serogroup switching could not be fully explained by either more frequent, shorter recombinations, nor by genetic linkage to genes involved in β–lactam resistance. This suggested the observed pattern was a consequence of selection for preserving serogroup. Phenotyping of strains constructed to express different serotypes in common genetic backgrounds was used to test whether genotypes were physiologically adapted to particular serogroups. These data were consistent with epistatic interactions between the cps locus and the rest of the genome that were specific to serotype, but not serogroup, meaning they were unlikely to account for the observed distribution of capsule types. Exclusion of these genetic and physiological hypotheses suggested future work should focus on alternative mechanisms, such as host immunity spanning multiple serotypes within the same serogroup, which might explain the observed pattern

Combined pancreaticoduodenectomy and colon resection for locally advanced peri-ampullary tumours: analysis of peri-operative morbidity and mortality

AbstractBackgroundCombined pancreaticoduodenectomy (PD) and colonic resection may be necessary to achieve an R0 resection of peri-ampullary tumours. The aim of this study was to examine the morbidity and mortality associated with this procedure.MethodsA retrospective cohort study was performed comparing 607 patients who underwent a standard pancreaticoduodenectomy (S-PD) to 28 patients who had a concomitant colon resection and PD (PD-colon) over a 10-year period at an academic centre.ResultsPatients in the PD-colon group were more likely to have received neoadjuvant chemotherapy ± radiation (3/28, 11% versus 14/607, 2%, P = 0.024). Operative time was also longer (530 versus 410min, P < 0.001) and they were more likely to have had portal vein resections (9/28, 32% versus 76/607, 13%, P = 0.007). There was no difference in the intra-operative blood loss, length of stay, or overall complication rates. The PD-colon group had a higher rate of severe post-operative bleeding (4/28, 11% versus 8/607, 1%, P = 0.002). The post-operative mortality rates for the PD-colon and PD groups were 2/28 (7%) and 8/607 (1%), respectively (P = 0.068).ConclusionsPD-colon has an acceptable risk of peri-operative morbidity compared with S-PD in well-selected patients

Properties of recombinations affecting the <i>cps</i> locus.

<p>In each boxplot, the recombinations affecting the <i>cps</i> locus are grouped according to their inferred impact on serotype. The first three graphs describe the recombinations affecting the <i>cps</i> locus. The values represent (A) overall length of recombination, (B) position of the 5’ edge of the recombination relative to the 5’ edge of the <i>cps</i> locus, and (C) position of the 3’ edge of the recombination relative to the 3’ edge of the <i>cps</i> locus. In the latter two plots, negative values indicate the recombination boundary is within the <i>cps</i> locus. The boxplot in (D) represents the total length of genome-wide recombinations on the same phylogenetic branch as the serotype switching events.</p