Isotropic-Nematic Transition in Liquid-Crystalline Elastomers

In liquid-crystalline elastomers, the nematic order parameter and the induced strain vary smoothly across the isotropic-nematic transition, without the expected first-order discontinuity. To investigate this smooth variation, we measure the strain as a function of temperature over a range of applied stress, for elastomers crosslinked in the nematic and isotropic phases, and analyze the results using a variation on Landau theory. This analysis shows that the smooth variation arises from quenched disorder in the elastomer, combined with the effects of applied stress and internal stress.Comment: 4 pages, including 4 postscript figures, uses REVTeX

Magnetic moment of welded HTS samples: dependence on the current flowing through the welds

We present a method to calculate the magnetic moments of the high-temperature superconducting (HTS) samples which consist of a few welded HTS parts. The approach is generalized for the samples of various geometrical shapes and an arbitrary number of welds. The obtained relations between the sample moment and the density of critical current, which flows through the welds, allow to use the magnetization loops for a quantitative characterization of the weld quality in a wide range of temperatures and/or magnetic fields.Comment: RevTeX4, 4 pages, 2 figures. Submitted to Supercond. Sci. Techno

Soft and non-soft structural transitions in disordered nematic networks

Properties of disordered nematic elastomers and gels are theoretically investigated with emphasis on the roles of non-local elastic interactions and crosslinking conditions. Networks originally crosslinked in the isotropic phase lose their long-range orientational order by the action of quenched random stresses, which we incorporate into the affine-deformation model of nematic rubber elasticity. We present a detailed picture of mechanical quasi-Goldstone modes, which accounts for an almost completely soft polydomain-monodomain (P-M) transition under strain as well as a ``four-leaf clover'' pattern in depolarized light scattering intensity. Dynamical relaxation of the domain structure is studied using a simple model. The peak wavenumber of the structure factor obeys a power-law-type slow kinetics and goes to zero in true mechanical equilibrium. The effect of quenched disorder on director fluctuation in the monodomain state is analyzed. The random frozen contribution to the fluctuation amplitude dominates the thermal one, at long wavelengths and near the P-M transition threshold. We also study networks obtained by crosslinking polydomain nematic polymer melts. The memory of initial director configuration acts as correlated and strong quenched disorder, which renders the P-M transition non-soft. The spatial distribution of the elastic free energy is strongly dehomogenized by external strain, in contrast to the case of isotropically crosslinked networks.Comment: 19 pages, 15 EPS figure

Influence of periodontal disease on risk of dementia: a systematic literature review and a meta-analysis

This is an accepted manuscript of an article published by Springer in European Journal of Epidemiology on 12/06/2020, available online: https://doi.org/10.1007/s10654-020-00648-x The accepted version of the publication may differ from the final published version.Periodontal disease (PD) is common and increases cardiovascular diseases. However, it is unclear whether PD is associated with increased risk of dementia. We carried out a systematic review and meta-analysis to investigate the influence of PD on dementia. We projected the number of dementia cases to be saved by reducing PD prevalence in the world. We searched cohort and case–control studies reporting the association of PD with all dementia (or any specific type of dementia) through PubMed, MEDLINE, PsycINFO, SocINDEX, CINHAL, and CNKI until 7th November 2018. Five cohorts and seven case–control studies were identified for review. We pooled eligible data to calculate relative risk (RR) of dementia in relation to PD and computed the number of dementia cases saved through reducing PD prevalence. Of 12 studies, six were undertaken in Asia, four in Europe and two in America. Eleven studies showed a positive association between PD and the risk of dementia, of which 10 were significant, and one reported a non-significant inverse association. Overall their quality was good. Pooled RR of dementia in relation to PD from all high quality studies was 1.38 (95%CI 1.01–1.90); in the five cohorts was 1.18 (1.06–1.31) and in the two case–control studies 2.25 (1.48–3.42). A 50% reduction in the current prevalence of 20% of PD in the population could save 850,000 (630,000–1,420,000) patients with dementia in the world. PD could increase the risk of incident dementia. Preventing and treating PD could contribute to controlling the global epidemic of dementia.Professor Ruoling Chen and Dr Jie Tang thank an EU Grant from Horizon 2020 MSCA – DEMAIRPO #799247. Dr Kaarin Anstey is funded by NHMRC Fellowship #1102694. Dr Wu is the recipient of BBSRC [BB/P004695/1] and NIA [1R01AG049321-01A1] Grant for aging research. Dr Yuyou Yao, Associate Professor of Anhui Medical University, China is a visiting scholar at the Faculty of Education, Health and Wellbeing, University of Wolverhampton to support this study and has made valuable comments on the manuscript.Published versio

GRADE-Workshop in Freiburg

Am Freitag, 24. 3. und Samstag, 25. 3. 2006 veranstaltet das Deutsche Cochrane-Zentrum an der Universitätsklinik Freiburg i. Br. einen GRADE-Workshop für Ärzte, die Empfehlungen formulieren, für Leitlinien-Autoren, Autoren von HTA-Berichten und systematischen Übersichtsarbeiten und Entscheidungsträger im Gesundheitssystem. Im Workshop werden die Grundprinzipien der Qualitätsbewertung der "Evidenz" von Studien und die Auswirkung der Qualität auf die Stärke der Empfehlung (Grading the evidence) vermittelt. Als Werkzeug dazu dient eine dafür entwickelte spezielle Software, der Grade-Profiler. Fortbildungszertifikate sind bei der Landesärztekammer beantragt