Long range transport of ultra cold atoms in a far-detuned 1D optical lattice

We present a novel method to transport ultra cold atoms in a focused optical lattice over macroscopic distances of many Rayleigh ranges. With this method ultra cold atoms were transported over 5 cm in 250 ms without significant atom loss or heating. By translating the interference pattern together with the beam geometry the trap parameters are maintained over the full transport range. Thus, the presented method is well suited for tightly focused optical lattices that have sufficient trap depth only close to the focus. Tight focusing is usually required for far-detuned optical traps or traps that require high laser intensity for other reasons. The transport time is short and thus compatible with the operation of an optical lattice clock in which atoms are probed in a well designed environment spatially separated from the preparation and detection region.Comment: 14 pages, 6 figure

Supplementations of industrial multichamber parenteral nutrition bags in critically ill children: safety of the practice

Parenteral nutrition (PN) is sometimes required in critically ill children because of contraindication or intolerance to full enteral nutrition. European guidelines recommend favoring multichamber bag PN (MCB PN), when possible, for quality purposes and ease of use. The prescribers may adjust the MCB PN through supplementations to better fulfill patient needs. The objective of this study is to investigate the use and supplementations of MCB PN. This observational, single-center, retrospective study was conducted in a pediatric intensive care unit (PICU). We collected prescriptions of MCB PNs and their supplementations added directly into PN bags. A descriptive analysis and a comparison of electrolyte supplementations with the manufacturer's recommendations were undertaken. One hundred thirty-five children (median age 39.2 months [7.0-118.8]) were included, 1449 MCB PNs were administered, and 1652 supplementations were carried out in 736 PN bags. Thirty-two percent of supplementations were vitamins, 32.2% were trace elements, and 35.8% were electrolytes. Around 10% of electrolyte supplementations in PN bags were outside the manufacturer's recommendations. These nonconformities primarily concerned phosphate. This study showed the real-world clinical use of MCB PN in the PICU. Proper attention should be paid to septic risks and physicochemical risks to ensure efficient practice and safety of MCB PN use. [Abstract copyright: © 2022 The Authors. Nutrition in Clinical Practice published by Wiley Periodicals LLC on behalf of American Society for Parenteral and Enteral Nutrition.

Performance of a 229 Thorium solid-state nuclear clock

The 7.8 eV nuclear isomer transition in 229 Thorium has been suggested as an etalon transition in a new type of optical frequency standard. Here we discuss the construction of a "solid-state nuclear clock" from Thorium nuclei implanted into single crystals transparent in the vacuum ultraviolet range. We investigate crystal-induced line shifts and broadening effects for the specific system of Calcium fluoride. At liquid Nitrogen temperatures, the clock performance will be limited by decoherence due to magnetic coupling of the Thorium nucleus to neighboring nuclear moments, ruling out the commonly used Rabi or Ramsey interrogation schemes. We propose a clock stabilization based on counting of flourescence photons and present optimized operation parameters. Taking advantage of the high number of quantum oscillators under continuous interrogation, a fractional instability level of 10^{-19} might be reached within the solid-state approach.Comment: 28 pages, 9 figure

A high stability semiconductor laser system for a 88^{88}Sr-based optical lattice clock

We describe a frequency stabilized diode laser at 698 nm used for high resolution spectroscopy of the 1S0-3P0 strontium clock transition. For the laser stabilization we use state-of-the-art symmetrically suspended optical cavities optimized for very low thermal noise at room temperature. Two-stage frequency stabilization to high finesse optical cavities results in measured laser frequency noise about a factor of three above the cavity thermal noise between 2 Hz and 11 Hz. With this system, we demonstrate high resolution remote spectroscopy on the 88Sr clock transition by transferring the laser output over a phase-noise-compensated 200 m-long fiber link between two separated laboratories. Our dedicated fiber link ensures a transfer of the optical carrier with frequency stability of 7 \cdot 10^{-18} after 100 s integration time, which could enable the observation of the strontium clock transition with an atomic Q of 10^{14}. Furthermore, with an eye towards the development of transportable optical clocks, we investigate how the complete laser system (laser+optics+cavity) can be influenced by environmental disturbances in terms of both short- and long-term frequency stability.Comment: 9 pages, 9 figures, submitted to Appl. Phys.

Dynamic compaction of polyurethane foam: experiments and modelling

The framework of this paper is to investigate the mitigation ability of an expanded rigid polyurethane foam against extremely fast (>106 s−1) and intense ( >10 GPa) dynamic loadings. Cyclic quasi-static tests and dynamic experiments (gas gun and low inductance generator) have been performed to investigate the foam behaviour for strain rates ranging from 10−3 to 105 s−1. Analysis of the experimental results shows that the foam has an elastic behaviour phase followed by a compaction phase with significant permanent sets. Compaction threshold is about 8 MPa under quasi-static loading, and 21 MPa for strain rates above 104 s−1. A porous compaction model is used to represent the macroscopic behaviour of the foam for the whole range of strain rates. The parameters are identified from dynamic experimental results. The model is validated by comparing calculated velocity profiles with an explicit hydrocode and velocity profiles measured during the experiments

Dramatic increase of central venous catheter-related infections associated with a high turnover of the nursing team

International audienceBACKGROUND & AIMS: This retrospective study evaluated the impact of new organization during the moving to a new university pediatric hospital on the incidence of central catheter-related blood stream infections (CRBSIs) among children on long-term parenteral nutrition. METHODS: The study ran from April 2007 to March 2014, starting a year prior to reorganisation of the department of pediatric Hepato-Gastroenterology and Nutrition associated to moving the children to a new hospital in April 2008, and continuing for 6 years following the move. During this time, data from all children hospitalized in this department who received parenteral nutrition (PN) for more than 15 days were analysed. RESULTS: During this 7-years study, 183 children aged 4.6 +/- 0.5 years received prolonged PN. Intestinal diseases were the main aetiologies (89%), primarily short bowel syndrome (18.4%), Hirschsprung disease and CIPO (13.5%) and inflammatory bowel disease (13.8%). The mean durations of hospitalization and of PN during hospitalization were, respectively, 70 +/- 2.1 and 55.7 +/- 3.6 days. During the study period, 151 CRBSIs occurred in 77 children (42% of all patients), i.e. 14.8 septic episodes/1000 PN days and 12.0 septic episodes/1000 CVC days. No patient died of a central venous catheter-related infection. However, following the move from the older hospital to the newer one, the rate of CRBSIs significantly doubled, from 3.9/1000 to 8.8/1000 CVC days (p = 0.02). During the following 4 years, the incidence of CRBSIs tended to increase between the 2nd and the 5th year after the move: 11.3 (p = NS); 21.4 (p = 0.01); 17.3 (p = NS), 20.3/1000 (p = NS) CVC days. We also observed that after evaluations by the Department of Infection Control, nurse training and stabilization of the nursing team, the incidence decreased significantly from 20.3 to 11.1/1000 CVC days during the 6th year after the move (p = 0.01). CONCLUSION: Our results reveal the deleterious impact of the reorganization during the hospital moving on the CRBSI incidence rate, and the possible implication of inexperienced team of nurses

Increase of recurrent central line-associated bloodstream infections in children with home parenteral nutrition in a rehabilitation care facility compared to home

International audienceBACKGROUND AND AIMS: Central line-associated bloodstream infections (CLABSIs) are the main complication in children with home parenteral nutrition (HPN) and some patients develop recurrent CLABSIs (REC-CLABSIs), defined as two or more infections within six months. Our aims were to assess the incidence and to characterize the risk factors of REC-CLABSIs in children with HPN. METHODS: We characterized 79 HPN children from 2014 to 2019 and calculated the incidence of CLABSIs. To minimize the risk of bias related to the exposure time of the septic risk, we paired the patients according to their central venous catheter (CVC) dwell time. After analyzing the whole cohort, a univariate and multivariate unconditional logistic regression was performed on the paired cohort. RESULTS: We included 75 (94.9%) children with a mean age of 7.11 years. The rate of septicemia was 1.55/1000 CVC days, mainly with Staphyloccocus sp. The patients with recurrent CLABSIs (REC group) represented 25% of the cohort, with an incidence of 2.99/1000 CVC days. In the whole cohort, a higher risk of recurrent infections was significantly associated with a longer CVC dwell time (OR = 1.04, IC 95% [1.01-1.06], p = 0.004), and with care located in rehabilitation care facilities (RCF) compared to home (OR = 6, IC 95% [1.5-26.6], p = 0.012). When children were paired according to their CVC dwell time, only in univariate analysis did the care in RCF remain significant (OR = 6.27, IC 95% [1.21-32.5], p = 0.03). CONCLUSIONS: Recurrent CLABSIs incidence was 2.99/1000 CVC days. Our study suggests that preventive measures should be implemented especially in RCFs to reduce the proportion of children with recurrent infections. A multicenter study is needed to confirm our results in a larger cohort with several RCFs