NEAT-FT: the European fiber link collaboration

The development of clocks based on optical transitions during the past three decades culminates in the availability of optical clocks with unprecedented stability and uncertainty . Simultaneously, increasing requirements for accurate time and frequency signals, e.g. for tests of fundamental physics or novel applications in relativistic geodesy, put forward new challenges. Typically, such applications rely on the comparison of two remote clocks. Thus, major challenges are how to synchronize these clocks over long distances or how to get the time or frequency signal of a clock to the location where it is required. It is generally agreed that optical fiber links are an excellent alternative to established satellite based distant clock comparison and synchronization techniques. A European joint research project called Network for European Accurate Time and Frequency Transfer (NEAT-FT) has been initiated in 2011 to lay the foundations for a novel approach to disseminate high-precision timing and ultrastable frequency signals by using existing fiber infrastructure. Since Europe has a large number of modern ultra-precise clocks, special emphasis is put on the development of new techniques for time transfer and phase-coherent comparison of remotely located optical clocks and the feasibility of a European fibre network connecting optical clocks in Europe. This talk highlights recent achievements and discusses some applications and prospects

Body mass index and alignment and their interaction as risk factors for progression of knees with radiographic signs of osteoarthritis

SummaryObjectiveTo investigate in which way body mass index (BMI) and alignment affect the risk for knee osteoarthritis (OA) progression.MethodsRadiographs of 181 knees from 155 patients (85% female, mean age 60 years) with radiographic signs of OA were analyzed at baseline and after 6 years. Progression was defined as 1-point increase in joint space narrowing score in the medial or lateral tibiofemoral (TF) compartment or having knee prosthesis during the follow-up for knees with a Kellgren and Lawrence score ≥1 at baseline. BMI at baseline was classified as normal (<25kg/m2), overweight (25–30) and obese (>30). Knee alignment on baseline radiographs was categorized as normal (TF angle between 182° and 184°) and malalignment (<182° or >184°). We estimated the risk ratio (RR) with 95% confidence interval for knee OA progression for overweight and obese patients and for malaligned knees relative to normal using generalized estimating equations (GEE). Additionally, we estimated the added effect when BMI and malalignment were present together on progression of knee OA. Adjustments were made for age and sex.ResultsSeventy-six knees (42%) showed progression: 27 in lateral and 66 in medial compartment. Knees from overweight and obese patients had an increased risk for progression (RR 2.4 (1.–3.6) and 2.9 (1.7–4.1), respectively). RRs of progression for malaligned, varus and valgus knee were 2.0 (1.3–2.8), 2.3 (1.4–3.1), and 1.7 (0.97–2.6), respectively. When BMI and malalignment were included in one model, the effect of overweight, obesity and malalignment did not change. The added effect when overweight and malalignment were present was 17%.ConclusionOverweight is associated with progression of knee OA and shows a small interaction with alignment. Losing weight might be helpful in preventing the progression of knee OA