Elastic and magnetic effects on the infrared phonon spectra of MnF2

We measured the temperature dependent infrared reflectivity spectra of MnF2 between 4 K and room temperature. We show that the phonon spectrum undergoes a strong renormalization at TN. The ab-initio calculation we performed on this compound accurately predict the magnitude and the direction of the phonon parameters changes across the antiferromagnetic transition, showing that they are mainly induced by the magnetic order. In this material, we found that the dielectric constant is mostly from phonon origin. The large change in the lattice parameters with temperature seen by X-ray diffraction as well as the A2u phonon softening below TN indicate that magnetic order induced distortions in MnF2 are compatible with the ferroelectric instabilities observed in TiO2, FeF2 and other rutile-type fluorides. This study also shows the anomalous temperature evolution of the lower energy Eu mode in the paramagnetic phase, which can be compared to that of the B1g one seen by Raman spectroscopy in many isostructural materials. This was interpreted as being a precursor of a phase transition from rutile to CaCl2 structure which was observed under pressure in ZnF2.Comment: 8 pages, 8 figures, updated version accepted in PR

Recollection of childhood abdominal pain in adults with functional gastrointestinal disorders

It is hypothesized that adults who can recall abdominal pain as children are at risk of experiencing a functional gastrointestinal disorder (FGID), but this is not specific to any particular FGID. The aim of this study was to evaluate the association between recollecting abdominal pain as a child and experiencing a FGID

Health Care Seeking for Abdominal Bloating and Visible Distention

Background While knowledge has accumulated regarding health care seeking in several functional gastrointestinal disorders (FGIDs), little is known about health care seeking in those with bloating and distention. Aim To identify predictors of health care seeking for bloating and distention. Methods The validated Talley Bowel Disease Questionnaire was mailed to a cohort selected at random from the population of Olmsted County, Minnesota; 2259 subjects (53% females; mean age 62 years) answered questions about bloating and distention. The complete medical record of each respondent was reviewed. Logistic regression was used to compare consulting for bloating and distention with consulting for other GI symptoms, and nonconsulters. Results A total of 131 (6%) subjects in the community consulted a physician for bloating or distention. Older age [odds ratio (OR), 1.8; 95% confidence interval (CI): 1.5, 2.1], higher somatic symptom scores (OR, 2.0; CI: 1.4, 2.8), lower education level (OR, 2.7; CI: 1.2, 5.6), early satiety (OR, 2.0; CI: 1.1, 3.8) and abdominal pain (OR, 2.4; CI: 1.6, 3.7) were associated with people seeking health care for bloating or distention vs. non-consulters. Similarly, older age (OR, 1.4; CI: 1.2, 1.7), chronic constipation (OR, 2.0; CI: 1.2, 3.2) and visible distention (OR, 3.0; CI: 1.8, 4.9) had greater odds of presenting for bloating or distention compared with presenting for other GI symptoms; somatic symptoms were not a predictor (OR, 1.1; CI: 0.8, 1.5). Conclusions Factors that lead people to present for bloating and distention are similar to those for other GI symptoms visits; however, specific biological rather than somatic features may predict visits for bloating and distention