Environment-mediated long-ranged correlations in many-body system.

Quantum states in complex aggregates are unavoidably affected by environmental effects, which typically cannot be accurately modeled by simple Markovian processes. As system sizes scale up, nonperturbative simulation becomes thus unavoidable, but they are extremely challenging due to the intimate interplay of intrinsic many-body interaction and time-retarded feedback from environmental degrees of freedom. In this work, we utilize the recently developed quantum dissipation with minimally extended state space approach to address reservoir induced long-ranged temporal correlations in finite size Ising-type spin chains.

Taming Quantum Noise for Efficient Low Temperature Simulations of Open Quantum Systems.

The hierarchical equations of motion (HEOM), derived from the exact Feynman-Vernon path integral, is one of the most powerful numerical methods to simulate the dynamics of open quantum systems. Its applicability has so far been limited to specific forms of spectral reservoir distributions and relatively elevated temperatures. Here we solve this problem and introduce an effective treatment of quantum noise in frequency space by systematically clustering higher order Matsubara poles, equivalent to an optimized rational decomposition.

Is Previous Periacetabular Osteotomy Associated with Pregnancy, Delivery, and Peripartum Complications?

Background: Surgical candidates for periacetabular osteotomy are commonly women of reproductive age with symptomatic acetabular dysplasia. However, little is known about how this surgical intervention contributes to the decision to become pregnant, obstetrical counseling regarding delivery, mode of delivery, or pregnancy-related complications.

Questions/purposes: (1) Does a history of periacetabular osteotomy affect a patient's decision to become pregnant or does it affect obstetrical counseling regarding the safety of pregnancy and childbirth? (2) Is history of periacetabular osteotomy associated with in an increased risk of undergoing cesarean section compared with the national average? (3) Is a history of periacetabular osteotomy associated with increased complications, decreased infant birth weight, preterm delivery?

Methods: In conjunction with obstetrician colleagues, we created a survey to investigate patient attitudes toward pregnancy, mode of delivery, pregnancy-related complications, and obstetrical counseling among female patients who previously underwent periacetabular osteotomy.

Large-for-gestational age and stillbirth: is there a role for antenatal testing?

Objective: To investigate the association between large-for-gestational-age (LGA) pregnancy and stillbirth to determine if the LGA fetus may benefit from antenatal testing with non-stress test or biophysical profile.

Methods: This was a retrospective cohort study of singleton pregnancies that were ongoing at 24 weeks' gestation and that had undergone routine second-trimester anatomy ultrasound examination, during the period 1990 to 2009. Pregnancies complicated by fetal anomaly or aneuploidy, those with missing birth weight information and those that were small-for-gestational age were excluded.

Optimal control of open quantum systems: cooperative effects of driving and dissipation.

We investigate the optimal control of open quantum systems, in particular, the mutual influence of driving and dissipation. A stochastic approach to open-system control is developed, using a generalized version of Krotov's iterative algorithm, with no need for Markovian or rotating-wave approximations. The application to a harmonic degree of freedom reveals cooperative effects of driving and dissipation that a standard Markovian treatment cannot capture.