ABSTRACT
A delay modulator, made of glass plates rotating in a pump beam, is applied to measure time-resolved rates of transient processes in a pump-probe experimental setup. Glass plates modulate both delay and beam power. The contribution from the power modulation is subtracted by using a scaled-down measurement made with metal chopper blades. Delay modulation results obtained with this procedure are consistent with the derivative in delay of the usual power modulation and can show a larger signal to noise ratio.
ABSTRACT
Time-resolved pump-probe measurements were made at variable heat accumulation in Co/Pd superlattices. Heat accumulation increases the baseline temperature and decreases the equilibrium magnetization. Transient ultrafast demagnetization first develops with higher fluence in parallel with strong equilibrium thermal spin fluctuations. The ultrafast demagnetization is then gradually removed as the equilibrium temperature approaches the Curie temperature. The transient magnetization time-dependence is well fit with the spin-flip scattering model.
ABSTRACT
A model of demagnetizing fields and micromagnetic simulations are applied to examine the evolution of a demagnetized cylinder. In addition to three expected final magnetic structures, a fourth switched state is obtained over a range of magnetic energy densities. The switched state is absent when demagnetizing fields are neglected. The connection to all-optical switching of materials with perpendicular magnetic anisotropy is discussed.
ABSTRACT
All-optical switching by domain wall motion has been obtained in Co/Pd superlattices with a TiS oscillator. Heat accumulation is part of the switching process for our experimental conditions. Numerical calculations point to a connection between domain wall motion and in-plane heat diffusion.
Subject(s)
Embolization, Therapeutic/methods , Hemophilia A/complications , Postpartum Hemorrhage/therapy , Adult , Female , Humans , PregnancySubject(s)
Cryptosporidiosis , Pregnancy Complications, Parasitic , Adult , Cryptosporidiosis/diagnosis , Cryptosporidiosis/parasitology , Cryptosporidiosis/therapy , Female , Humans , Pregnancy , Pregnancy Complications, Parasitic/diagnosis , Pregnancy Complications, Parasitic/parasitology , Pregnancy Complications, Parasitic/therapyABSTRACT
OBJECTIVE: To determine the incidence, risk factors, presentation, treatment and morbidity associated with secondary postpartum haemorrhage. DESIGN: Analysis of 132 consecutive women presenting with secondary postpartum haemorrhage occurring over a three-year period. SETTING: The maternity unit in a district general teaching hospital serving an annual delivery rate of around 6500 women. MAIN OUTCOME MEASURES: Factors associated with the cause of the haemorrhage and the resulting morbidity. RESULTS: Most women presented during the second week after delivery. A history of primary postpartum haemorrhage (OR 9.3; 95% CI 6.2-14.0) and manual removal of placenta (OR 3.5; 95% CI 1.6-7.5) were the only significant risk factors identified. There was a high associated morbidity, with 84% requiring hospital admission, 63% surgical evacuation, 17% blood transfusion, with three women suffering a uterine perforation, one managed by hysterectomy. In women undergoing evacuation only, 37% had retained placental tissue confirmed after surgery; pre-operative ultrasound examination did not provide a better discrimination over clinical assessment for this finding. CONCLUSIONS: Secondary postpartum haemorrhage occurs in just under 1% of women, is associated with primary postpartum haemorrhage and retained placenta, and may result in significant maternal morbidity. This problem deserves more attention than it has received in recent years.
