Characterizing quantum dynamics with initial system-environment correlations

We fully characterize the reduced dynamics of an open quantum system initially correlated with its environment. Using a photonic qubit coupled to a simulated environment we tomographically reconstruct a superchannel---a generalised channel that treats preparation procedures as inputs---from measurement of the system alone, despite its coupling to the environment. We introduce novel quantitative measures for determining the strength of initial correlations, and to allow an experiment to be optimised in regards to its environment.Comment: 10 pages, 15 figure

Confinement of the Sun's interior magnetic field: some exact boundary-layer solutions

High-latitude laminar confinement of the Sun's interior magnetic field is shown to be possible, as originally proposed by Gough and McIntyre (1998) but contrary to a recent claim by Brun and Zahn (A&A 2006). Mean downwelling as weak as 2x10^-6cm/s -- gyroscopically pumped by turbulent stresses in the overlying convection zone and/or tachocline -- can hold the field in advective-diffusive balance within a confinement layer of thickness scale ~ 1.5Mm ~ 0.002 x (solar radius) while transmitting a retrograde torque to the Ferraro-constrained interior. The confinement layer sits at the base of the high-latitude tachocline, near the top of the radiative envelope and just above the `tachopause' marking the top of the helium settling layer. A family of exact, laminar, frictionless, axisymmetric confinement-layer solutions is obtained for uniform downwelling in the limit of strong rotation and stratification. A scale analysis shows that the flow is dynamically stable and the assumption of laminar flow realistic. The solution remains valid for downwelling values of the order of 10^-5cm/s but not much larger. This suggests that the confinement layer may be unable to accept a much larger mass throughput. Such a restriction would imply an upper limit on possible internal field strengths, perhaps of the order of hundreds of gauss, and would have implications also for ventilation and lithium burning. The solutions have interesting chirality properties not mentioned in the paper owing to space restrictions, but described at http://www.atmos-dynamics.damtp.cam.ac.uk/people/mem/papers/SQBO/solarfigure.htmlComment: 6 pages, 3 figures, to appear in conference proceedings: Unsolved Problems in Stellar Physic

OncoLog Volume 51, Number 09, September 2006

Zeroing In on a Moving Target New Life for an Old Drug House Call: Managing Your Medications DiaLog: Adjuvant Therapy for Aggressive Kidney Cancer, by Christopher G. Wood, MD, Associate Professor of Urology and Cancer Biologyhttps://openworks.mdanderson.org/oncolog/1184/thumbnail.jp

Resolution of Clinical Signs of Ventilator-Associated Pneumonia in Trauma Patients

Objectives: The ATS/IDSA Ventilator-Associated Pneumonia (VAP) guidelines suggest that clinical improvement of VAP should be apparent within 3–6 days. This study evaluated resolution of clinical signs of VAP in trauma patients after diagnosis. Methods: Critically injured adults admitted to the trauma intensive care unit (ICU) from June 1, 2006, to December 31, 2007, and subsequently given a diagnosis of VAP were retrospectively assessed. Clinical signs, including derangements of maximum temperature (Tmax), white blood cell (WBC) count, and PaO2/FiO2, were evaluated on days 1–16 after VAP diagnosis. Data are presented as mean ± SD unless otherwise stated. Clinical parameters after VAP were compared using repeated-measures ANOVA with the Tukey test for multiple comparisons. Results: A total of 82 patients were identified. Data for the 34 patients without concurrent infections are presented. Demographic data include: Age 46 ± 17 years; 71% men; 94% blunt trauma; median (IQR) Injury Severity Score 29.5 (24–38); duration of mechanical ventilation 33 ± 27 days; ICU length of stay (LOS) 39 ± 25 days; hospital LOS 53 ± 33 days. Clinical signs following VAP diagnosis: Tmax (°F): Day 1=101.8 ± 1.3, Day 3=101.1 ± 1.1, Day 6=101.1 ± 1.4, Day 16=100.1 ± 3. Compared to Day 1, there was a significant reduction in Tmax at days 10, 11, 12, 13, 14, and 16 (p\u3c0.05 for all). WBC count (cells per microliter): day 1 = 12.9 ± 5, day 3 = 13.7 ± 5, day 6 = 14.4 ± 5, and day 16 = 13.8 ± 6. There was no significant difference in WBC on days 1–16 (p=0.42). PaO2/FiO2: day 1 = 232 ± 108, day 3 = 200 ± 87, day 6 = 218 ± 104, day 16 = 246 ± 126. Differences in PaO2/FiO2 on days 1–16 did not reach statistical significance (p=0.06). Conclusion: Improvement of clinical parameters after a VAP diagnosis is delayed in trauma patients. Alternative methods for determining resolution should be investigated. Published in To be published in Critical Care Medicine’s December 2009 supplement

Third Dredge-up in Low Mass Stars: Solving the LMC Carbon Star Mystery

A long standing problem with asymptotic giant branch (AGB) star models has been their inability to produce the low-luminosity carbon stars in the Large and Small Magellanic Clouds. Dredge-up must begin earlier and extend deeper. We find this for the first time in our models of LMC metallicity. Such features are not found in our models of SMC metallicity. The fully implicit and simultaneous stellar evolution code STARS has been used to calculate the evolution of AGB stars with metallicities of Z=0.008 and Z=0.004, corresponding to the observed metallicities of the Large and Small Magellanic Clouds, respecitively. Third dredge-up occurs in stars of 1Msol and above and carbon stars were found for models between 1Msol and 3Msol. We use the detailed models as input physics for a population synthesis code and generate carbon star luminosity functions. We now find that we are able to reproduce the carbon star luminosity function of the LMC without any manipulation of our models. The SMC carbon star luminosity function still cannot be produced from our detailed models unless the minimum core mass for third dredge-up is reduced by 0.06Msol.Comment: 6 pages, 5 figures. Accepted for publication in MNRA