35 research outputs found
Earthquakes: from chemical alteration to mechanical rupture
In the standard rebound theory of earthquakes, elastic deformation energy is
progressively stored in the crust until a threshold is reached at which it is
suddenly released in an earthquake. We review three important paradoxes, the
strain paradox, the stress paradox and the heat flow paradox, that are
difficult to account for in this picture, either individually or when taken
together. Resolutions of these paradoxes usually call for additional
assumptions on the nature of the rupture process (such as novel modes of
deformations and ruptures) prior to and/or during an earthquake, on the nature
of the fault and on the effect of trapped fluids within the crust at
seismogenic depths. We review the evidence for the essential importance of
water and its interaction with the modes of deformations. Water is usually seen
to have mainly the mechanical effect of decreasing the normal lithostatic
stress in the fault core on one hand and to weaken rock materials via
hydrolytic weakening and stress corrosion on the other hand. We also review the
evidences that water plays a major role in the alteration of minerals subjected
to finite strains into other structures in out-of-equilibrium conditions. This
suggests novel exciting routes to understand what is an earthquake, that
requires to develop a truly multidisciplinary approach involving mineral
chemistry, geology, rupture mechanics and statistical physics.Comment: 44 pages, 1 figures, submitted to Physics Report
Sialic acid, periodontal pathogens and Tannerella forsythia: stick around and enjoy the feast!
Periodontal pathogens, like any other human commensal or pathogenic bacterium, must possess both the ability to acquire the necessary growth factors and the means to adhere to surfaces or reside and survive in their environmental niche. Recent evidence has suggested that sialic acid containing host molecules may provide both of these requirements in vivo for several periodontal pathogens but most notably for the red complex organism Tannerella forsythia. Several other periodontal pathogens also possess sialic acid scavenging enzymes – sialidases, which can also expose adhesive epitopes, but might also act as adhesins in their own right. In addition, recent experimental work coupled with the release of several genome sequences has revealed that periodontal bacteria have a range of sialic acid uptake and utilization systems while others may also use sialic acid as a cloaking device on their surface to mimic host and avoid immune recognition. This review will focus on these systems in a range of periodontal bacteria with a focus on Ta. forsythia
Localization and activities of nitrogenase, glutamine synthetase and glutamate synthase in Azotobacter vinelandii grown in oxygen-controlled continuous culture
On the relationship of intracytoplasmic to cytoplasmic membranes in nitrogen-fixing Azotobacter vinelandii
Whole cell respiration and nitrogenase activities in Azotobacter vinelandii growing in oxygen controlled continuous culture
Development and validation of a self-report version of the Spinal Cord Independence Measure (SCIM III).
Study design:Cross-sectional validation study.Objectives:To develop and validate a self-report version of the Spinal Cord Independence Measure (SCIM III).Setting:Two SCI rehabilitation facilities in Switzerland.Methods:SCIM III comprises 19 questions on daily tasks with a total score between 0 and 100 and subscales for 'self-care', 'respiration & sphincter management' and 'mobility'. A self-report version (SCIM-SR) was developed by expert discussions and pretests in individuals with spinal cord injury (SCI) using a German translation. A convenience sample of 99 inpatients with SCI was recruited. SCIM-SR data were analyzed together with SCIM III data obtained from attending health professionals.Results:High correlations between SCIM III and SCIM-SR were observed. Pearson's r for the total score was 0.87 (95% confidence interval (CI) 0.82-0.91), for the subscales self-care 0.87 (0.81-0.91); respiration & sphincter management 0.81 (0.73-0.87); and mobility 0.87 (0.82-0.91). Intraclass correlations were: total score 0.90 (95% CI 0.85-0.93); self-care 0.86 (0.79-0.90); respiration & sphincter management 0.80 (0.71-0.86); and mobility 0.83 (0.76-0.89). Bland-Altman plots showed that patients rated their functioning higher than professionals, in particular for mobility. The mean difference between SCIM-SR and SCIM III for the total score was 5.14 (point estimate 95% CI 2.95-7.34), self-care 0.89 (0.19-1.59), respiration & sphincter management 1.05 (0.18-2.28 ) and mobility 3.49 (2.44-4.54). Particularly patients readmitted because of pressure sores rated their independence higher than attending professionals.Conclusion:Our results support the criterion validity of SCIM-SR. The self-report version may facilitate long-term evaluations of independence in persons with SCI in their home situation