Measuring entanglement of photons produced by a pulsed source

A pulsed source of entangled photons is desirable for some applications. Yet, such a source has intrinsic problems arising from the simultaneous arrival of the signal and noise photons to the detectors. These problems are analyzed and practical methods to calculate the number of accidental (or spurious) coincidences are described in detail, and experimentally checked, for the different regimes of interest. The results are useful not only to measure entanglement, but to all the situations where extracting the number of valid coincidences from noisy data is required. As an example of the use of those methods, we present the time-resolved measurement of the Concurrence of the field produced by spontaneous parametric down conversion with pump pulses of duration in the ns-range at a repetition of kHz. The predicted discontinuous evolution of the entanglement at the edges of the pump pulse is observed.Comment: 9 pages, 10 or 7 figures (one of the figures includes 4), 28 Refernce

Predictability of adverse outcomes in hypertensive disorders of pregnancy: a multicenter prospective cohort study

Objectives To explore variables associated with adverse maternal/fetal/neonatal outcomes among pregnant/postpartum patients admitted to ICU for hypertensive disorders of pregnancy (HDP). Methods Multicenter, prospective, national cohort study. Results Variables independently associated with maternal/fetal/neonatal mortality among 172 patients were as follows: Acute Physiology and Chronic Health Evaluation-II (APACHE-II)(OR1.20[1.06–1.35]), gestational age (OR0.698[0.59–0.82]) and aspartate aminotransferase (AST)(OR1.004[1.001–1.006]). Positive likelihood ratio for headache, epigastric pain, and visual disturbances to predict composite adverse outcomes were 1.23(1.16–1.30), 0.76(0.59–1.02), and 1.1(0.98–1.2), respectively. Conclusions Maternal/fetal mortality due to HDP was independently associated with severity of illness on admission, gestational age, and elevated AST. Accuracy of clinical symptoms to predict composite adverse outcomes was low