The rhythm of coupled metronomes

Spontaneous synchronization of an ensemble of metronomes placed on a freely rotating platform is studied experimentally and by computer simulations. A striking in-phase synchronization is observed when the metronomes' beat frequencies are fixed above a critical limit. Increasing the number of metronomes placed on the disk leads to an observable decrease in the level of the emerging synchronization. A realistic model with experimentally determined parameters is considered in order to understand the observed results. The conditions favoring the emergence of synchronization are investigated. It is shown that the experimentally observed trends can be reproduced by assuming a finite spread in the metronomes' natural frequencies. In the limit of large numbers of metronomes, we show that synchronization emerges only above a critical beat frequency value.Comment: 10 pages, 10 Figure

Fondaparinux for the treatment of superficial vein thrombosis in the legs

Producción CientíficaThe efficacy and safety of anticoagulant treatment for patients with acute, symptom- atic superf icial-vein thrombosis in the legs, but without concomitant deep-vein thrombosis or symptomatic pulmonary embolism at presentation, have not been es- tablished. Methods In a randomized, double-blind trial, we assigned 3002 patients to receive either fonda- parinux, administered subcutaneously at a dose of 2.5 mg once daily, or placebo for 45 days. The primary eff icacy outcome was a composite of death from any cause or symptomatic pulmonary embolism, symptomatic deep-vein thrombosis, or symp- tomatic extension to the saphenofemoral junction or symptomatic recurrence of superf icial-vein thrombosis at day 47. The main safety outcome was major bleeding. The patients were followed until day 77. Results The primary eff icacy outcome occurred in 13 of 1502 patients (0.9%) in the fonda- parinux group and 88 of 1500 patients (5.9%) in the placebo group (relative risk reduction with fondaparinux, 85%; 95% conf idence interval [CI], 74 to 92; P<0.001). The incidence of each component of the primary efficacy outcome was significantly reduced in the fondaparinux group as compared with the placebo group, except for the outcome of death (0.1% in both groups). The rate of pulmonary embolism or deep-vein thrombosis was 85% lower in the fondaparinux group than in the pla- cebo group (0.2% vs. 1.3%; 95% CI, 50 to 95; P<0.001). Similar risk reductions were observed at day 77. A total of 88 patients would need to be treated to prevent one instance of pulmonary embolism or deep-vein thrombosis. Major bleeding occurred in one patient in each group. The incidence of serious adverse events was 0.7% with fondaparinux and 1.1% with placebo. Conclusions Fondaparinux at a dose of 2.5 mg once a day for 45 days was effective in the treat- ment of patients with acute, symptomatic superf icial-vein thrombosis of the legs and did not have serious side effects. (Funded by GlaxoSmithKline; ClinicalTrials .gov number, NCT00443053.

A simple clinical method for predicting the benefit of prone vs. supine positioning in reducing heart exposure during left breast radiotherapy

Background and purpose: The benefit of reduced radiation heart exposure in the prone vs. supine position individually differs. In this prospective cohort study, the goal was to develop a simple method for the operation of a validated model for the prediction of preferable treatment position during left breast radiotherapy. Material and methods: In 100 cases, a single CT slice was utilized for the collection of the needed patientspecific data (in addition to body mass index, the distance of the LAD from the chest wall and the area of the heart included in the radiation fields at the middle of the heart in the supine position). Outcome was analyzed in relation to the full CT series acquired in both positions and dosimetric data. Results: Great consistency was found between the tested and original method regarding sensitivity and specificity. The prioritization of LAD dose, and the use of heart dose and position-specific dose constraints as safety measures ensure sensitivity and specificity values of 82.8% and 87.3%, respectively. In an additional ‘‘routine clinical practice” series of 60 patients the new method seemed feasible in routine clinical practice. External testing on a 28-case series indicated similar accuracy. Conclusion: We consider this simple clinical tool appropriate for assisting individual positioning aiming at maximum heart protection during left breast irradiatio

von Willebrand factor antigen latex immunoassays are affected to a different extent by rheumatoid factor

status: publishe