21 research outputs found
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