Non-destructive detection of large molecules without mass limitation.

The problem for molecular identification knows many solutions, which include mass spectrometers whose mass sensitivity depends on the performance of the detector involved. The purpose of this article is to show by means of molecular dynamics simulations how a laser-cooled ion cloud, confined in a linear radio-frequency trap, can reach the ultimate sensitivity providing the detection of individual charged heavy molecular ions. In our simulations, we model the laser-cooled Ca+ ions as two-level atoms, confined thanks to a set of constant and time oscillating electrical fields. A singly charged molecular ion with a mass of 106 amu is propelled through the ion cloud. The induced change in the fluorescence rate of the latter is used as the detection signal. We show that this signal is due to a significant temperature variation triggered by the Coulomb repulsion and amplified by the radio-frequency heating induced by the trap itself. We identify the optimum initial energy for the molecular ion to be detected, and furthermore, we characterize the performance of the detector for a large range of confinement voltages.

National survey on the non-pharmacological modalities prescribed by French general practitioners in the treatment of lower limb (knee and hip) osteoarthritis. Adherence to the EULAR recommendations and factors influencing adherence.

BACKGROUND: Guidelines for the treatment of lower limb osteoarthritis (LLOA) include non-pharmacological (NPM) and pharmacological modalities (PM). In France, general practitioners (GPs) are the main prescribers of pharmacological treatment for LLOA but little is known about the non-pharmacological modalities they usually prescribe. OBJECTIVE: To determine how French GPs prescribe non-pharmacological modalities of LLOA treatment in daily practice. METHODS: A four-point questionnaire (systematically, frequently, rarely, never) was built to assess the French GPs' opinion regarding the NPM of LLOA treatment (10 questions). The questionnaire was given between April and June 2005 to 3000 GPs, all over the French regions. The percentage reported in this abstract are those of the systematic and frequent responses. RESULTS: 59.2% of the questionnaires (n=1775) could be retrieved. Weight reduction recommendations (76%), joint sparing (71.7%), physical activity development (61.7%), rehabilitation (57.8%), self-exercise (46%) were the more frequently prescribed NPM. Sticks (36%), insoles (35.6%), bed relief (25.4%) and knee bracing (10.5%) were far less regularly proposed. However weight reduction and physical activity development appeared to be the patients less-well observed NPM. The main means used to improve the efficacy of the diet were the support of a nutritionist (74.5%) and the support of the GPs (70.7%) far beyond the support group and familial intervention (both 36,6%). The large majority of GPs considered that a good physical activity was essential (51.7%) or useful (43.3%) to the success of the weight reduction programme. The main recommended physical activities were walking (84.3%), swimming (74.3%), cycling (47%) and water-gymnastics (40.4%). To improve the success of the physical activity development, analgesics were recommended by 93% of GPs, settling up through rehabilitation by 57.4%, support through GPs appointments by 50%. Lastly, 68.4% of GPs recommended a systematic analgesic consumption, since a non-steroidal anti-infammatory drug (NSAID) prescription was proposed by only 30.5%, and NSAID treatment before or after physical activities by 19% and 9.3% respectively. CONCLUSION: This large survey shows that non-pharmacological modalities are frequently prescribed by French GPs in the treatment of LLOA, in addition to analgesic therapy. However, most GPs consider that some of them are difficult to follow in the long term.

Correcting symmetry imperfections in linear multipole traps.

Multipole radio-frequency (RF) traps are central to collisional experiments in cryogenic environments. They also offer possibilities to generate new type of ion crystals topologies and in particular the potential to create infinite 1D/2D structures: ion rings and ion tubes. However, multipole traps have also been shown to be very sensitive to geometrical misalignment of the trap rods, leading to additional local trapping minima. The present work proposes a method to correct non-ideal potentials, by modifying the applied RF amplitudes for each trap rod. This approach is discussed for the octupole trap, leading to the restitution of the ideal Mexican-Hat-like pseudo-potential, expected in multipole traps. The goodness of the compensation method is quantified in terms of the choice of the diagnosis area, the residual trapping potential variations, the required adaptation of the applied RF voltage amplitudes, and the impact on the trapped ion structures. Experimental implementation for macroscopic multipole traps is also discussed, in order to propose a diagnostic method with respect to the resolution and stability of the trap drive. Using the proposed compensation technique, we discuss the feasibility of generating a homogeneous ion ring crystal, which is a measure of quality for the obtained potential well.

Antipyretic efficacy and safety of a single intravenous administration of 15 mg/kg paracetamol versus 30 mg/kg propacetamol in children with acute fever due to infection.

OBJECTIVES: An intravenous formulation of paracetamol and an intravenous formulation of propacetamol (prodrug of paracetamol) were compared in children with acute fever due to infection in order to determine the antipyretic efficacy and safety during the 6-hour period after administration. METHODS: A total of 67 patients aged 1 month to 12 years and with a rectal body temperature between 38.5 degrees C and 41 degrees C, were randomized to receive either intravenous paracetamol 15 mg/kg (n = 35) or propacetamol 30 mg/kg (n = 32) under double-blind conditions. RESULTS: The non-inferiority of intravenous paracetamol compared to propacetamol was demonstrated (non-inferiority margin = 0.5 degrees C) by the median body temperature reduction of 1.9 degrees C in the intravenous paracetamol group and the reduction of 2.05 degrees C in the propacetamol group. The difference in the incidence of local adverse events was statistically significant (p = 0.0134) with more local adverse events in the propacetamol group (9, 28.1%) than in the intravenous paracetamol group (2, 5.7%). CONCLUSION: This double-blind, randomized, clinical trial demonstrates the non-inferiority of a single administration of 15 mg/kg intravenous paracetamol in comparison to 30 mg/kg propacetamol in terms of body temperature reduction in children aged 1 month to 12 years with acute fever due to infection. It confirms the better local safety of intravenous paracetamol in comparison to propacetamol.

Terahertz frequency standard based on three-photon coherent population trapping.

A scheme for a terahertz frequency standard based on three-photon coherent population trapping in stored ions is proposed. Assuming the propagation directions of the three lasers obey the phase matching condition, we show that stability of few 10(-14) at 1 s can be reached with a precision limited by power broadening to 10(-11) in the less favorable case. The referenced terahertz signal can be propagated over long distances, the useful information being carried by the relative frequency of the three optical photons.

First line treatment of knee osteoarthritis in outpatients in France: adherence to the EULAR 2000 recommendations and factors influencing adherence.

OBJECTIVES: To document adherence to two parts of the EULAR 2000 recommendations for knee osteoarthritis, concerning non-pharmacological and pharmacological first line management; and to identify factors influencing adherence to the recommendations. METHODS: In a prospective study, 1030 randomly selected French general practitioners completed questionnaires about three unselected outpatients with osteoarthritis, and about their own practice, knowledge, and agreement with the EULAR 2000 recommendations. Percentages of adherence of their prescriptions to both parts of the recommendation were calculated, and probabilities of non-adherence analysed in relation to patient and physician related characteristics, using multilevel logistic regression analysis. RESULTS: Data were obtained from 967 physicians and 2430 patients. The EULAR 2000 recommendations were familiar to 79% of the GPs; 99% agreed with the non-pharmacological part and 97% with the pharmacological part. Adherence to the two parts was 74.8% and 73.6%, but 54.2% for both together. Factors increasing adherence to the non-pharmacological recommendation were patient body mass index >35 kg/m(2) (odds ratio 0.11 (95% confidence interval, 0.06 to 0.21)), patient's stated preference for a treatment (OR 0.43 (0.55 to 0.97)), and physician's regular continuance of medical education (OR 0.76 (0.59 to 0.98)); patient's age and duration of symptoms decreased adherence. Factors increasing adherence to the pharmacological recommendation were gastrointestinal disease (OR 0.50 (0.35 to 0.72)) and physician's knowledge of the EULAR recommendations (OR 0.75 (0.60 to 0.93)). CONCLUSIONS: Although most physicians agreed with the EULAR 2000 recommendations, adherence was only approximately 75% for each of the non-pharmacological and pharmacological recommendations and 54% for both together.