Common Fermi-liquid origin of T-squared resistivity and superconductivity in n-type SrTiO3

A detailed analysis is given of the T^2 term in the resistivity observed in electron-doped SrTiO3. Novel bandstructure data are presented, which provide values for the bare mass, density of states, and plasma frequency of the quasiparticles as a function of doping. It is shown that these values are renormalized by approximately a factor 2 due to electron-phonon interaction. It is argued that the quasiparticles are in the anti-adiabatic limit with respect to electron-phonon interaction. The condition of anti-adiabatic coupling renders the interaction mediated through phonons effectively non-retarded. We apply Fermi-liquid theory developed in the 70's for the T^2 term in the resistivity of common metals, and combine this with expressions for Tc and with the Brinkman-Platzman-Rice (BPR) sum-rule to obtain Landau parameters of n-type SrTiO3. These parameters are comparable to those of liquid 3He, indicating interesting parallels between these Fermi-liquids despite the differences between the composite fermions from which they are formed.Comment: 12 pages, 9 figure

Spin resonance in EuTiO3 probed by time-domain GHz ellipsometry

We show an example of a purely magnetic spin resonance in EuTiO3 and the resulting new record high Faraday rotation of 590 deg/mm at 1.6 T for 1 cm wavelengths probed by a novel technique of magneto-optical GHz time-domain ellipsometry. From our transmission measurements of linear polarized light we map out the complex index of refraction in the GHz to THz range. We observe a strong resonant absorption by magnetic dipole transitions involving the Zeeman split S=7/2 magnetic energy levels of the Eu 2+ ions, which causes a very large dichroism for circular polarized radiation.Comment: 4 pages, 4 figure

No significant improvement of cardiovascular disease risk indicators by a lifestyle intervention in people with familial hypercholesterolemia compared to usual care: results of a randomised controlled trial

Background: People with Familial Hypercholesterolemia (FH) may benefit from lifestyle changes supporting their primary treatment of dyslipidaemia. This project evaluated the efficacy of an individualised tailored lifestyle intervention on lipids (low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), total cholesterol (TC) and triglycerides), systolic blood pressure, glucose, body mass index (BMI) and waist circumference in people with FH. Methods: Adults with FH (n= 340), recruited from a Dutch cascade screening program, were randomly assigned to either a control group or an intervention group. The personalised intervention consisted of web-based tailored lifestyle advice and personal counselling. The control group received care as usual. Lipids, systolic blood pressure, glucose, BMI, and waist circumference were measured at baseline and after 12 months. Regression analyses were conducted to examine differences between both groups. Results: After 12 months, no significant between-group differences of cardiovascular disease (CVD) risk indicators were observed. LDL-C levels had decreased in both the intervention and control group. This difference between intervention and control group was not statistically significant. Conclusions: This project suggests that an individually tailored lifestyle intervention did not have an additional effect in improving CVD risk indicators among people with FH. The cumulative effect of many small improvements in all indicators on long term CVD risk remains to be assessed in future studies. Trial registration: NTR1899 at ww.trialregister.nl.© 2012 Broekhuizen et al

Lifetime vigorous but not light-to-moderate habitual physical activity impacts favorably on carotid stiffness in young adults the Amsterdam growth and health longitudinal study

Higher levels of habitual physical activity favorably impact on arterial stiffness. It is not clear, however, whether lifetime habitual physical activities of different intensities carry the same protective effect and to what extent any such effect is mediated by other biological cardiovascular risk factors. We, therefore, examined longitudinal data on habitual physical activity and cardiovascular risk factors (8 repeated measures between the ages of 13 and 36 years) in 373 subjects in whom stiffness estimates of the carotid artery were assessed at age 36 years using noninvasive ultrasonography. The time spent in habitual physical activities (in minutes per week) throughout the longitudinal period was compared between subjects across tertiles of the following stiffness estimates: β-stiffness index, distensibility and compliance coefficients, and the Young's elastic modulus. After adjustments for sex, body height, and other lifestyle variables, subjects in the highest tertile of the β-stiffness index (ie, with stiffer arteries) had spent, on average, throughout the longitudinal period, less time in vigorous (-26.5 [95% CI:-45.9 to-7.1]) but less so in light-to-moderate habitual physical activities (-11.2 [95% CI:-53.5 to 31.1]) as compared with subjects in the lowest tertile. The difference in time spent in vigorous activities was greatly attenuated when further adjusted for blood lipids, cardiorespiratory fitness, fat distribution, resting heart rate, and mean arterial pressure (to-11.2 [95% CI:-29.4 to 7.0]). Similar results were found for the other stiffness estimates. Promoting vigorous intensity physical activities among the healthy young may, therefore, prevent arterial stiffness and related cardiovascular sequelae later in life, partly through its favorable impact on other biological cardiovascular risk factors