Infectious diseases in the first year of life, perinatal characteristics and childhood acute leukaemia

The objective of the present study was to investigate the role of early common infections and perinatal characteristics in the aetiology of childhood common leukaemia. A case-control study was conducted from 1995 to 1998 in France, and included 473 incident cases of acute leukaemia (AL) (408 acute lymphoblastic leukaemia (ALL), 65 acute myeloid leukaemia (AML) age-, sex- and region-matched with 567 population-based controls. Data on the medical history of the child and his/her environment were collected using self-administered questionnaires. Analyses were conducted using nonconditional logistic regression. A slight negative association with early infections was observed (OR=0.8; 95% CI (0.6-1.0)). The association was stronger for early gastrointestinal infections. Early day-care was found to be associated with a decreased risk of AL (OR=0.6; 95% CI (0.4-0.8) and OR=0.8; 95% CI (0.5-1.2) for day-care starting before age 3 months and between 3 and 6 months, respectively). No association with breast-feeding was observed, irrespective of its duration. A birth order of 4 or more was associated with a significantly increased risk of AL (OR=2.0; 95% CI (1.1-3.7) with ALL). A history of asthma was associated with a decreased risk of ALL (OR 0.5; 95% CI (0.3-0.90). Although the results regarding birth order and breast-feeding do not fit with Greaves' hypothesis, the study supports the hypothesis that early common infections may play a protective role in the aetiology of childhood leukaemia, although this effect was not more marked for common ALL

Rotating tomography Paris-Edinburgh cell:a novel portable press for micro-tomographic 4-D imaging at extreme pressure/temperature/stress conditions

International audienceThis paper presents details of instrumental development to extend synchrotron X-ray microtomography techniques to in situ studies under static compression (high pressure), shear stress or the both conditions at simultaneous high temperatures. To achieve this, a new rotating tomography Paris–Edinburgh cell has been developed. This ultra-compact portable device easily and successfully adapted to various multi-modal synchrotron experimental set-up at ESRF, SOLEIL and DIAMOND is explained in detail. An in-depth description of proof of concept first experiments performed on a high resolution imaging beamline is then given, which illustrate the efficiency of the set-up and the data quality that can be obtained

Infections in early life and childhood leukaemia risk: a UK case–control study of general practitioner records

We investigated infections in early life (diagnosed in general practice) and subsequent risk of childhood leukaemia in the UK General Practice Research Database (GPRD). All children born at GPRD practices and subsequently diagnosed with leukaemia were identified as cases and were individually matched (on year of birth, sex and practice) to up to 20 controls. The final analysis included 162 leukaemia cases and 2215 matched controls. Conditional logistic regression demonstrated no evidence that children with one or more recorded infection in the first year of life had a reduced risk of leukaemia (OR=1.05, 95%CI 0.69, 1.59; P=0.83) or acute lymphoblastic leukaemia (ALL; OR=1.05, 95%CI 0.64–1.74; P=0.84). Our study provides no support for the Greaves hypothesis, which proposes that reduced or delayed exposure to infections in early life increases the risk of childhood ALL

A meta-analysis of the association between day-care attendance and childhood acute lymphoblastic leukaemia

Background Childhood acute lymphoblastic leukaemia (ALL) may be the result of a rare response to common infection(s) acquired by personal contact with infected individuals. A meta-analysis was conducted to examine the relationship between day-care attendance and risk of childhood ALL, specifically to address whether early-life exposure to infection is protective against ALL

Mechanism and kinetics of the a-b transition in San Carlos olivine Mg1.8Fe0.2SiO4

International audienceThe mechanism and kinetics of the a-b transformation in San Carlos olivine a- Mg1.8Fe0.2SiO4 containing ca. 526 wt.ppm H2O were studied in situ by time-resolved synchrotron X-ray diffraction (XRD) in the range 12.5 - 14.5 GPa and 870 - 1150 K. Time series of XRD spectra reveal the early formation of an intermediate phase that further transforms to wadsleyite (b-phase). This intermediate phase may be either a metastable ringwoodite (g-phase) or the disordered spinelloid phase proposed in the pseudomartensitic reaction model. Both microstructural and kinetic data suggest that the transformation rates are controlled by growth processes after the early saturation of nucleation sites along olivine grain boundaries. Growth rates in the range 1.7 10 12 - 2.1 10 9 m.s 1 are estimated by fitting the transformation-time data to the Cahn rate equation and define an activation enthalpy for growth ΔHa = 204(55) kJ/mol. Compared to the previous studies performed on pure forsterite Mg2SiO4, these new kinetic results point out an increase of transformation rates with the iron content. Hence, the persistence of a metastable olivine wedge to depths > 660 km might be restricted to even colder and/or dryer subduction zones than previously estimated

High-speed tomography under extreme conditions at the PSICHE beamline of the SOLEIL Synchrotron

In situ microtomography at high pressure and temperature has developed rapidly in the last decade, driven by the development of new high-pressure apparatus. It is now routinely possible to characterize material under high pressure with acquisition times for tomograms of the order of tens of minutes. Here, advantage was taken of the possibility to combine the use of a pink beam projected through a standard Paris-Edinburgh press in order to demonstrate the possibility to perform high-speed synchrotron X-ray tomography at high pressure and temperature allowing complete high-resolution tomograms to be acquired in about 10 s. This gives direct visualization to rapidly evolving or unstable systems, such as flowing liquids or reacting components, and avoids assumptions in the interpretation of quenched samples. Using algebraic reconstruction techniques allows the missing angle artefacts that result from the columns of the press to be minimized

Viscosity of silicate melts: the effect of volatiles (CO<SUB>2,</SUB>H<SUB>2</SUB>O) at HP and HT.

International audienceThe presence of melts in the first part of upper mantle is image by many geophysical studies. The nature of these melts is referring by different petrological and experimental studies that show a melt rich in volatiles, principally in CO2. To apprehend the deep carbon cycle, the first necessity is to know the mobility of these melts, like the viscosity. As a function of geodynamical context, the temperature and the pressure change, therefore different carbonated melts are produce. In this study, we investigate different SiO2/CO2/H2O content in melt to determine their influences on the viscosity. To investigate the viscosity, the experiment is making in ESRF in Grenoble. We produce in-situ measurements in Paris Edinburg cell with falling sphere viscometry experiments. Experiments are produce between 1 and 3 GPa and liquid temperature of sample. One result show a viscosity of 0.15 Pa.s for 20wt% of CO2. It is one order of magnitude more viscous than dolomite (Kono et al., 2013) and average 5 times less viscous than basalt (Sakamaki et al., 2013). Primarily results obtain in ESRF show a no linear effect of SiO2/CO2 content. Volatiles have an effect on viscosity and this has implication on melt migration in the mantle, so on the deep carbon cycle

Viscosity of silicate melts: the effect of volatiles (CO<SUB>2,</SUB>H<SUB>2</SUB>O) at HP and HT.

International audienceThe presence of melts in the first part of upper mantle is image by many geophysical studies. The nature of these melts is referring by different petrological and experimental studies that show a melt rich in volatiles, principally in CO2. To apprehend the deep carbon cycle, the first necessity is to know the mobility of these melts, like the viscosity. As a function of geodynamical context, the temperature and the pressure change, therefore different carbonated melts are produce. In this study, we investigate different SiO2/CO2/H2O content in melt to determine their influences on the viscosity. To investigate the viscosity, the experiment is making in ESRF in Grenoble. We produce in-situ measurements in Paris Edinburg cell with falling sphere viscometry experiments. Experiments are produce between 1 and 3 GPa and liquid temperature of sample. One result show a viscosity of 0.15 Pa.s for 20wt% of CO2. It is one order of magnitude more viscous than dolomite (Kono et al., 2013) and average 5 times less viscous than basalt (Sakamaki et al., 2013). Primarily results obtain in ESRF show a no linear effect of SiO2/CO2 content. Volatiles have an effect on viscosity and this has implication on melt migration in the mantle, so on the deep carbon cycle