Surface state charge dynamics of a high-mobility three dimensional topological insulator

We present a magneto-optical study of the three-dimensional topological insulator, strained HgTe using a technique which capitalizes on advantages of time-domain spectroscopy to amplify the signal from the surface states. This measurement delivers valuable and precise information regarding the surface state dispersion within <1 meV of the Fermi level. The technique is highly suitable for the pursuit of the topological magnetoelectric effect and axion electrodynamics.Comment: Published version, online Sept 23, 201

Oxygen isotope effect and phase separation in the optical conductivity of (La0.5_{0.5}Pr0.5_{0.5})0.7_{0.7}Ca0.3_{0.3}MnO3_3 thin films

The optical conductivities of films of (La$_{0.5}$Pr$_{0.5}$)$_{0.7}$Ca$_{0.3}$MnO$_3$ with different oxygen isotopes ($^{16}$O and $^{18}$O) have been determined in the spectral range from 0.3 to 4.3 eV using a combination of transmission in the mid-infrared and ellipsometry from the near-infrared to ultra-violet regions. We have found that the isotope exchange strongly affects the optical response in the ferromagnetic phase in a broad frequency range, in contrast to the almost isotope-independent optical conductivity above $T_C$. The substitution by $^{18}$O strongly suppresses the Drude response and a mid-infrared peak while enhancing the conductivity peak at 1.5 eV. A qualitative explanation can be given in terms of the phase separation present in these materials. Moreover, the optical response is similar to the one extracted from measurements in polished samples and other thin films, which signals to the importance of internal strain.Comment: 11 pages, 11 figures, to appear in PR

Many-body large polaron optical conductivity in SrTi1−x_{1-x}Nbx_xO3_3

Recent experimental data on the optical conductivity of niobium doped SrTiO$_{3}$ are interpreted in terms of a gas of large polarons with effective coupling constant $\alpha_{eff}\approx2$. The {theoretical approach takes into account} many-body effects, the electron-phonon interaction with multiple LO-phonon branches, and the degeneracy and the anisotropy of the Ti t$_{2g}$ conduction band. {Based on the Fr\"{o}hlich interaction, the many-body large-polaron theory} provides an interpretation for the essential characteristics, except -- interestingly -- for the unexpectedly large intensity of a peak at $\sim130$ meV, of the observed optical conductivity spectra of SrTi$_{1-x}$Nb$_{x}$O$_{3}$ \textit{without} any adjustment of material parameters.Comment: to appear in Phys. Rev.

Sports-related injuries in primary health care

Introduction. Sports activities play an important role in today’s society. However, as more people become involved in these activities, the number of sports-related injuries also increases. In the Netherlands, 3.5 million sports injuries occur annually. Twenty per cent of these injuries are first seen by a GP. Little is known about the epidemiology of these injuries in general practice. This study has been conducted to determine the incidence and prevalence of sports-related injuries in general practice and to provide information about the nature and treatment of these injuries

Improving poverty reduction in Europe: what works best where?

This article examines how income poverty is affected by changes to the scale of tax-benefit policies and which are the most cost-effective policies in reducing poverty or limiting its increase in seven diverse EU countries. We do that by measuring the implications of increasing/reducing the scale of each policy instrument, using microsimulation methods while holding constant the policy design and national context. We consider commonly applied policy instruments with a direct effect on household income: child benefits, social assistance, income tax lower thresholds and a benchmark case of rescaling the whole tax-benefit system. We find that the assessment of the most cost-effective instrument may depend on the measure of poverty used and the direction and scale of the change. Nevertheless, our results indicate that the options that reduce poverty most cost-effectively in most countries are increasing child benefits and social assistance, while reducing the former is a particularly poverty-increasing way of making budgetary cuts

The relationship of objectively measured physical activity and sedentary behaviour with gestational weight gain and birth weight

OBJECTIVE: To evaluate the relationship of physical activity (PA) and sedentary behaviour with gestational weight gain (GWG) and birth weight. DESIGN: Combined data from two prospective studies: (1) nulliparous pregnant women without BMI restrictions and (2) overweight and obese pregnant women at risk for gestational diabetes. METHODS: Daily PA and sedentary behaviour were measured with an accelerometer around 15 and at 32-35 weeks of gestation. The association between time spent in moderate-to-vigorous PA (MVPA) and in sedentary activities with GWG and birth weight was determined. Main outcome measures were GWG between 15 and 32 weeks of gestation, average GWG per week, and birth weight. RESULTS: We studied 111 women. Early in pregnancy, 32% of women spent ≥ 30 minutes/day in at least moderate PA versus 12% in late pregnancy. No significant associations were found between time spent in MVPA or sedentary behaviour with GWG or birth weight. CONCLUSIONS: We found no relation between MVPA and sedentary behaviour with GWG or birth weight. The small percentage of women meeting the recommended levels of PA indicates the need to inform and support pregnant women to maintain regular PA, as there seems to be no adverse effect on birth weight and maintaining PA increases overall health.Anneloes E. Ruifrok, Ellen Althuizen, Nicolette Oostdam, Willem van Mechelen, Ben Willem Mol, Christianne J. M. de Groot and Mireille N. M. van Poppe