Use of depot medroxyprogesterone acetate and fracture risk

Depot medroxyprogesterone acetate (DMPA), which has a high rate of use among teenagers in Europe and the United States, has been associated with impaired bone mineral acquisition during adolescence and accelerated bone loss in later life. Studies on the association between DMPA use and fracture risk are limited.; We aimed at evaluating the relationship between use of hormonal contraceptives, specifically DMPA, and fracture risk.; We conducted a case-control analysis using the United Kingdom-based General Practice Research Database.; Participants were females aged 20-44 yr with an incident fracture diagnosis between 1995 and 2008.; Odds ratios (OR) with 95% confidence intervals (CI) of incident fracture in relation to exposure to DMPA or combined oral contraceptives were assessed. Adjustments were made for smoking, body mass index, and additional potential confounders.; We identified 17,527 incident fracture cases and 70,130 control patients (DMPA exposure: 11 and 8%, respectively). Compared with nonuse, current use of one to two, three to nine, or 10 or more DMPA prescriptions yielded adjusted OR for fractures of 1.18 (95% CI = 0.93-1.49), 1.36 (95% CI = 1.15-1.60), and 1.54 (95% CI = 1.33-1.78), respectively. Fracture risk was highest after longer treatment duration (<2-3 yr), and there was no difference in patients below and above the age of 30 yr. For users of combined estrogen-containing oral contraceptives, the OR were around 1.; This population-based study suggests that use of DMPA is associated with a slightly increased risk of fractures

Spin dynamics and coherent tunnelling in the molecular magnetic rings Fe_6 and Fe_8

We present detailed calculations of low-energy spin dynamics in the ``ferric wheel'' systems Na:Fe_6 and Cs:Fe_8 in a magnetic field. We compute by exact diagonalisation the low-energy spectra and matrix elements for total-spin and N'eel-vector components, and thus the time-dependent correlation functions of these operators. Comparison of our results with the semiclassical theory of coherent quantum tunnelling of the N'eel vector demonstrates the validity of a two-state description for the low-energy dynamics of ferric wheels. We discuss the implications of our results for mesoscopic quantum coherent phenomena, and for the experimental techniques to observe them, in molecular magnetic rings.Comment: 10 pages, 8 figures; considerably expanded discussion; to appear in Eur. Phys. J.

Strategies to valorise agrobiodiversity

The current food value chain is characterised by a highly standardised offer produced in an increasingly monotonous agricultural system. In parallel, there is a growing interest among consumers for traditional or regional crop varieties. The conservation of these crops is often done by civil society organisations like Arche Noah, Pro Specie Rara, Rete Semi Rurali, Réseau Semence Paysanne or Red Andaluza de Semillas. Some networks sell their food products in local niche markets, specialised stores and supermarkets. To increase their visibility, some producer groups in the networks are interested in developing or improving a label to valorise agrobiodiversity to the consumer. Based on a representative consumer survey in four European countries, we show that consumer awareness with respect to traditional, old varieties is low but the interest in "Diversifood", defined as more diverse, locally adapted, healthy and tasty produce, is substantial. Therefore, we state, that the availability of a label to valorise agrobiodiversity would respond to consumer needs and increase the visibility of the work done by the networks – but only if it is embedded in an appropriate communication strategy aimed at raising consumer awareness about agrobiodiversity

Vortices and charge order in high-T_c superconductors

We theoretically investigate the vortex state of the cuprate high-temperature superconductors in the presence of magnetic fields. Assuming the recently derived nonlinear $\sigma$-model for fluctuations in the pseudogap phase, we find that the vortex cores consist of two crossed regions of elliptic shape, in which a static charge order emerges. Charge density wave order manifests itself as satellites to the ordinary Bragg peaks directed along the axes of the reciprocal copper lattice. Quadrupole density wave (bond order) satellites, if seen, are predicted to be along the diagonals. The intensity of the satellites should grow linearly with the magnetic field, in agreement with the result of recent experiments

Pairing gaps near ferromagnetic quantum critical points

We address the quantum-critical behavior of a two-dimensional itinerant ferromagnetic systems described by a spin-fermion model in which fermions interact with close to critical bosonic modes. We consider Heisenberg ferromagnets, Ising ferromagnets, and the Ising nematic transition. Mean-field theory close to the quantum critical point predicts a superconducting gap with spin-triplet symmetry for the ferromagnetic systems and a singlet gap for the nematic scenario. Studying fluctuations in this ordered phase using a nonlinear sigma model, we find that these fluctuations are not suppressed by any small parameter. As a result, we find that a superconducting quasi-long-range order is still possible in the Ising-like models but long-range order is destroyed in Heisenberg ferromagnets.Comment: 13 pages, 7 figure

Prevention of restenosis after coronary angioplasty: A pharmacological approach

Evaluations of drugs for the prevention of resrenosis after human coronary angioplasty have been disappointing. Heparin failed to reduce resrenosis in a randomized study in Atlanta, Georgia, in patients maintained on heparin for 24 h. A randomized study in the same centre compared acetylsalicylic acid to anricoagulation with coumadin. Restenosis was slightly but nor significantly less frequent in patients on acelylsalicylic acid. An American multicentre randomized study comparing a combination of acetylsalicylic acid and dipyridamole to ticlopidine and to placebo revealed no difference in tertns of incidence of restenosis. Dipyridamole alone shows no effect against acute or late coronary artery resrenosis. Two calcium antagonists (diltiazem and nifedipine) did not significantly diminish restenosis in randomized trials. Neither did a thromboxane A inhibitor. Only eicosapentaenoic acid (EPA), an n-3fatty acid, significantly reduced reslenosis in a randomized study using a high dose. But the same compound proved ineffective in a similar study using a somewhat lower dose. Despite scientific evidence for the inefficacy of virtually all tested compounds, I do not know of a single institution that does not continue to discharge its patients after coronary angioplasty on one or several of the