978 research outputs found
Effect of closed endotracheal suction in high-frequency ventilated premature infants measured with electrical impedance tomography
Objective: To determine the global and regional changes in lung volume during and after closed endotracheal tube (ETT) suction in high-frequency ventilated preterm infants with respiratory distress syndrome (RDS). Design: Prospective observational clinical study. Setting: Neonatal intensive care unit. Patients: Eleven non-muscle relaxed preterm infants with RDS ventilated with open lung high-frequency ventilation (HFV). Interventions: Closed ETT suction. Measurements and results: Changes in global and regional lung volume were measured with electrical impedance tomography. ETT suction resulted in an acute loss of lung volume followed by spontaneous recovery with a median residual loss of 3.3% of the maximum volume loss. The median stabilization time was 8 s. At the regional level, the lung volume changes during and after ETT suction were heterogeneous in nature. Conclusions: Closed ETT suction causes an acute, transient and heterogeneous loss of lung volume in premature infants with RDS treated with open lung HFV
Exploration of Non-Resonant Divertor Features on the Compact Toroidal Hybrid
Non-resonant divertors (NRDs) separate the confined plasma from the
surrounding plasma facing components (PFCs). The resulting striking field line
intersection pattern on these PFCs is insensitive to plasma equilibrium
effects. However, a complex scrape-off layer (SOL), created by chaotic magnetic
topology in the plasma edge, connects the core plasma to the PFCs through
varying magnetic flux tubes. The Compact Toroidal Hybrid (CTH) serves as a
test-bed to study this by scanning across its inductive current. Simulations
observe a significant change of the chaotic edge structure and an effective
distance between the confined plasma and the instrumented wall targets. The
intersection pattern is observed to be a narrow helical band, which we claim is
a resilient strike line pattern. However, signatures of finger-like structures,
defined as heteroclinic tangles in chaotic domains, within the plasma edge
connect the island chains to this resilient pattern. The dominant connection
length field lines intersecting the targets are observed via heat flux
modelling with EMC3-EIRENE. At low inductive current levels, the excursion of
the field lines resembles a limited plasma wall scenario. At high currents, a
private flux region is created in the area where the helical strike line
pattern splits into two bands. These bands are divertor legs with distinct SOL
parallel particle flow channels. The results demonstrate the NRD strike line
pattern resiliency within CTH, but also show the underlying chaotic edge
structure determining if the configuration is diverted or limited. This work
supports future design efforts for a mechanical structure for the NRD.Comment: 26 pages, 16 figure
Real measurements and Quantum Zeno effect
In 1977, Mishra and Sudarshan showed that an unstable particle would never be
found decayed while it was continuously observed. They called this effect the
quantum Zeno effect (or paradox). Later it was realized that the frequent
measurements could also accelerate the decay (quantum anti-Zeno effect). In
this paper we investigate the quantum Zeno effect using the definite model of
the measurement. We take into account the finite duration and the finite
accuracy of the measurement. A general equation for the jump probability during
the measurement is derived. We find that the measurements can cause inhibition
(quantum Zeno effect) or acceleration (quantum anti-Zeno effect) of the
evolution, depending on the strength of the interaction with the measuring
device and on the properties of the system. However, the evolution cannot be
fully stopped.Comment: 3 figure
Stochastic simulations of the quantum Zeno effect
Published versio
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