Background: Postpartum hemorrhage (PPH) is a major source of maternal morbidity. Objectives: This study's objective was to determine whether changes in hemostasis markers during the course of PPH are ...predictive of its severity. Patients and methods: We enrolled 128 women with PPH requiring uterotonic prostaglandin E2 (sulprostone) infusion. Two groups were defined (severe and non‐severe PPH) according to the outcome during the first 24 hours. According to our criteria, 50 of the 128 women had severe PPH. Serial coagulation tests were performed at enrollment (H0), and 1, 2, 4 and 24 hours thereafter. Results: At H0, and through H4, women with severe PPH had significantly lower fibrinogen, factor V, antithrombin activity, protein C antigen, prolonged prothrombin time, and higher D‐dimer and TAT complexes than women with non‐severe PPH. In multivariate analysis, from H0 to H4, fibrinogen was the only marker associated with the occurence of severe PPH. At H0, the risk for severe PPH was 2.63‐fold higher for each 1 gL−1 decrease of fibrinogen. The negative predictive value of a fibrinogen concentration >4 gL−1 was 79% and the positive predictive value of a concentration ≤2 gL−1 was 100%. Conclusion: These findings indicate that a simple fibrinogen measurement can anticipate the risk of severe bleeding in PPH.
For many years, lunar laser ranging (LLR) observations using a green wavelength have suffered an inhomogeneity problem both temporally and spatially. This paper reports on the implementation of a new ...infrared detection at the Grasse LLR station and describes how infrared telemetry improves this situation. Our first results show that infrared detection permits us to densify the observations and allows measurements during the new and the full Moon periods. The link budget improvement leads to homogeneous telemetric measurements on each lunar retro-reflector. Finally, a surprising result is obtained on the Lunokhod 2 array which attains the same efficiency as Lunokhod 1 with an infrared laser link, although those two targets exhibit a differential efficiency of six with a green laser link.
Recent progress in the domain of time and frequency (T/F) standards requires important improvements of existing time distribution links. Among these, the accuracy of time transfer is actually an ...important part of the concerns in order to establish and maintain time & space references from ground and/or space facilities. Several time transfers by laser link projects have been carried out over the past 10 years with numerous scientific and metrological objectives. Satellite Laser ranging (SLR) has proven to be a fundamental tool, offering a straightforward, conceptually simple, highly accurate and unambiguous observable. Depending on the mission, LR is used to transmit time over two-way or one-way distances from 500 to several millions of km. The following missions and their objectives employed this technique: European Laser Timing (ELT) at 450 km, Time Transfer by Laser Link (T2L2) at 1,336 km, Laser Time Transfer (LTT) at 36,000 km, Lunar Reconnaissance Orbiter (LRO) at 350,000 km, and MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) at tens of million km. This article describes the synergy between SLR and T/F technologies developed on the ground and in space and as well as the state of the art of their exploitation. The performance and sources of limitation of such space missions are analyzed. It shows that current and future challenges lie in the improvement of the time accuracy and stability of the time for ground geodetic observatories. The role of the next generation of SLR systems is emphasized both in space and at ground level, from the point of view of GGOS and valuable exploitation of the synergy between time synchronization, ranging and data transfer.
We have previously described a microbiological process for the conversion of lactose into 3′sialyllactose and other ganglioside sugars by living
Escherichia coli cells expressing the appropriate ...recombinant glycosyltransferase genes. In this system the activated sialic acid donor (CMP-Neu5Ac) was generated from exogenous sialic acid, which was transported into the cells by the permease NanT. Since sialic acid is an expensive compound, a more economical process has now been developed by genetically engineering
E. coli K12 to be capable of generating CMP-Neu5Ac using its own internal metabolism. Mutant strains devoid of Neu5Ac aldolase and of ManNAc kinase were shown to efficiently produce 3′sialyllactose by coexpressing the α-2,3-sialyltransferase gene from
Neisseria meningitidis with the
neuC,
neuB and
neuA
Campylobacter jejuni genes encoding
N-acetylglucosamine-6-phosphate-epimerase, sialic acid synthase and CMP-Neu5Ac synthetase, respectively. A sialyllactose concentration of 25
g
l
−1 was obtained in long-term high cell density culture with a continuous lactose feed. This high concentration and low cost of fermentation medium should make possible to use sialylated oligosaccharides in new fields such as the food industry.
The T2L2 project (time transfer by laser link) allows for the synchronization of remote ultra-stable clocks over intercontinental distances (Fridelance et al 1997 Exp. Astron. 7, Samain and ...Fridelance 1998 Metrologia 35 151-9). The principle is derived from satellite laser ranging technology with dedicated space equipment designed to record arrival times of laser pulses at the satellite. The space segment has been launched in June 2008 as a passenger experiment on the ocean altimetry satellite Jason 2. T2L2 had been specified to yield a time stability of better than 1 ps over 1000 s integration time and an accuracy of better than 100 ps. This level of performance requires a rigorous data processing which can be performed only with a comprehensive calibration model of the whole instrumentation. For this purpose, several experimental measurements have been performed before and during the integration phase of the T2L2 space instrument. This instrument model is one of the cornerstones of the data reduction process which is carried out to translate the raw information to a usable picosecond time transfer. After providing a global synopsis of the T2L2 space instrument, the paper gives a description of the experimental setup for the instrument characterization. It then details the different contributions within the calibration model and concludes with an applied example of a space to ground time transfer.
The Time Transfer by Laser Link (T2L2) is a very high resolution time transfer technique based on the recording of arrival times of laser pulses at the satellite. T2L2 was designed to achieve time ...stability in the range of 1ps over 1000s and an accuracy better than 100ps. The project is in operation onboard the Jason-2 satellite since June 2008. The principle is based on the Satellite Laser Ranging (SLR) technology; it uses the input of 20–25 SLR stations of the international laser network which participate in the tracking. This paper focuses on the data reduction process which was developed specifically to transform the raw information given by both space instrument and ground network: first to identify the triplets (ground and onboard epochs and time of flight of the laser pulse), second to estimate a usable product in terms of ground-to-space time transfer (including instrumental corrections), and thirdly to produce synchronization between any pair of remote ground clocks. In describing the validation of time synchronizations, the paper opens a way for monitoring the time difference between ultra-stable clocks thanks to a laser link at a few ps level for Common View passes. It highlights however that without accurately characterizing the onboard oscillator of Jason-2 and knowing the unavailability of time calibrations of SLR stations generally, time transfer over intercontinental distances remain difficult to be accurately estimated.
Suppression ratio (SR) derived from bispectral index (BIS) monitoring is correlated to EEG burst suppression. It may occur during deep anaesthesia, but also in the case of metabolic or haemodynamic ...brain injury. The goal of the study was to describe the occurrence of SR and to determine factors associated with SR during propofol–remifentanil general anaesthesia maintenance.
We conducted a post hoc analysis of BIS recordings in consecutive patients included in two multi-centre trials, undergoing non-cardiac surgery using a dual closed-loop BIS controller allowing automated propofol–remifentanil administration. The percentage of time spent with a BIS value between 40 and 60 (TBIS 40–60) was measured. Two groups of patients were defined: the SR group, including patients with at least one episode of SR value >10% lasting more than 1 min, and the control group. Factors associated with SR were analysed using a stepwise multivariate analysis.
A total of 1494 patients age=57 (17) yr; TBIS 40–60=76 (17%) were analysed and 131 (8.7%) patients constituted the SR group. The main independent factors associated with SR were advanced age odds ratio (95% confidence interval)=4.80 (1.85–12.43) (P=0.027), 10.59 (3.76–29.81) (P<0.0001), for categories of age 60–80 and >80 yr, respectively, history of coronary artery disease (CAD) 2.53 (1.47–4.37) (P=0.001) and male gender 1.57 (1.03–2.40) (P=0.03).
The occurrence of SR during BIS-controlled propofol and remifentanil anaesthesia is mainly observed in elderly male patients or in patients with a history of CAD. The mechanisms underlying SR and the potential consequences for the patient's postoperative outcome remain unsolved.
The Time Transfer by Laser Link (T2L2) experiment on-board the Jason-2 satellite was launched in June 2008 at 1335km altitude. It has been designed to use the Satellite Laser Ranging (SLR) space ...technique as an optical link between ground and space clocks. T2L2, as all the instruments aboard Jason-2, is referenced to the Ultra Stable Oscillator (USO) provided by the Doppler Orbitography and Radio-positioning Integrated by Satellite (DORIS) system. A complex data processing has been developed in order to extract time & frequency products as the relative frequency bias of the USO from ground-to-space time transfer passages. The precision of these products was estimated of a few parts in 10−13 given the very good in-flight performance of T2L2 with a ground-to-space time stability of a few picoseconds (ps) over 100s. Frequency bias from T2L2 were compared with results from operational orbit computation, notably with the DIODE (Détermination Immédiate d’Orbite par Doris Embarqué) outputs (see Jayles et al. (2016) same issue) at the level of 1·10−12.
The present paper is focusing on the main physical effects which drive the frequency variations of the Jason-2 USO during its flight, notably over the South Atlantic Anomaly (SAA) area. In addition to the effects of radiation we studied the effect of the residual temperature variations, in the range 8–11°C (measured on-board). A model was established to represent these effects on the short term with empirical coefficients (sensitivities of the USO) to be adjusted. The results of fitting the model over ∼200 10-day periods, from 2008 to 2014, show the sensitivities of the Jason-2 USO to temperature and radiation. The analysis of the 6-year output series of empirical coefficients allows us to conclude that: (i) the temperature to frequency dependence is very stable along time at the level of around −1.2·10−12per°C, (ii) the radiation effects are much lower than those previously detected on the Jason-1 USO with a factor>10. The swept material used by manufacturers for the Jason-2 quartz oscillator has such properties to avoid non-linear effects >1–2·10−12, (iii) the model is available at 1min or less over the Jason-2 mission, with a level of consistency of 5·10−13, which is the average RMS of the post-fit residuals.
The Time Transfer by Laser Experiment (T2L2) on the Jason 2 satellite is a mission allowing remote clocks synchronization at the picosecond level. It is based on laser ranging technologies, with a ...laser station network on the ground and a dedicated instrument on board the satellite. It was launched in June 2008 and has been working continuously since then. T2L2 performances are very promising for time and frequency metrology and also for fundamental physics. The scientific objectives of the whole experiment rely on a rigorous uncertainty budget. This is governed by the characteristics of the space instrument and the laser stations network, the post treatment done on the ground, and also the process used to calibrate the laser stations. The uncertainty budget demonstrates that T2L2 is able to perform common-view time transfers between remote sites with an expanded uncertainty better than 140 ps (coverage factor = 2).
When fed to a β-galactosidase-negative (lacZ–) Escherichia coli strain that was grown on an alternative carbon source (such as glycerol), lactose accumulated intracellularly on induction of the ...lactose permease. We showed that intracellular lactose was efficiently glycosylated when genes of glycosyltransferase that use lactose as acceptor were expressed. High-cell-density cultivation of lacZ– strains that overexpressed the β1,3 N acetyl glucosaminyltransferase lgtA gene of Neisseria meningitidis resulted in the synthesis of 6 g · L–1 of the expected trisaccharide (GlcNAcβ1-3Galβ1-4Glc). When the β1,4 galactosyltransferase lgtB gene of N. meningitidis was coexpressed with lgtA, the trisaccharide was further converted to lacto-N-neotetraose (Galβ1-4GlcNAcβ1-3Galβ1-4Glc) and lacto-N-neoheaxose with a yield higher than 5 g · L–1. In a similar way, the nanA– E. coli strain that was devoid of NeuAc aldolase activity accumulated NeuAc on induction of the NanT permease and the lacZ– nanA– strain that overexpressed the N. meningitidis genes of the α2,3 sialyltransferase and of the CMP-NeuAc synthase efficiently produced sialyllactose (NeuAcα2-3Galβ1-4Glc) from exogenous NeuAc and lactose.
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