Mannitol dry powder challenge in comparison with exercise testing in children

Rationale Mannitol dry powder (MDP) challenge is an indirect bronchial provocation test, which is well studied in adults but not established for children. Objective We compared feasibility, validity, and clinical significance of MDP challenge with exercise testing in children in a clinical setting. Methods Children aged 6–16 years, referred to two respiratory outpatient clinics for possible asthma diagnosis, underwent standardized exercise testing followed within a week by an MDP challenge (Aridol™, Pharmaxis, Australia). Agreement between the two challenge tests using Cohen's kappa and receiving operating characteristic (ROC) curves was compared. Results One hundred eleven children performed both challenge tests. Twelve children were excluded due to exhaustion or insufficient cooperation (11 at the exercise test, 1 at the MDP challenge), leaving 99 children (mean ± SD age 11.5 ± 2.7 years) for analysis. MDP tests were well accepted, with minor side effects and a shorter duration than exercise tests. The MDP challenge was positive in 29 children (29%), the exercise test in 21 (21%). Both tests were concordant in 83 children (84%), with moderate agreement (κ = 0.58, 95% CI 0.39–0.76). Positive and negative predictive values of the MDP challenge for exercise-induced bronchoconstriction were 68% and 89%. The overall ability of MDP challenge to separate children with or without positive exercise tests was good (area under the ROC curve 0.83). Conclusions MDP challenge test is feasible in children and is a suitable alternative for bronchial challenge testing in childhood. Pediatr. Pulmonol. 2011; 46:842–848. © 2011 Wiley-Liss, Inc.

Phenotypic plasticity is a negative, though weak, predictor of the commonness of 105 grassland species

Aim The usual hypothesis about the relationship between niche breadth and range size posits that species with the capacity to use a wider range of resources or to tolerate a greater range of environmental conditions should be more widespread. In plants, broader niches are often hypothesized to be due to pronounced phenotypic plasticity, and more plastic species are therefore predicted to be more common. We examined the relationship between the magnitude of phenotypic plasticity in five functional traits, mainly related to leaves, and several measures of abundance in 105 Central European grassland species. We further tested whether mean values of traits, rather than their plasticity, better explain the commonness of species, possibly because they are pre-adapted to exploiting the most common resources. Location Central Europe. Methods In a multispecies experiment with 105 species we measured leaf thickness, leaf greenness, specific leaf area, leaf dry matter content and plant height, and the plasticity of these traits in response to fertilization, waterlogging and shading. For the same species we also obtained five measures of commonness, ranging from plot-level abundance to range size in Europe. We then examined whether these measures of commonness were associated with the magnitude of phenotypic plasticity, expressed as composite plasticity of all traits across the experimental treatments. We further estimated the relative importance of trait plasticity and trait means for abundance and geographical range size. Results More abundant species were less plastic. This negative relationship was fairly consistent across several spatial scales of commonness, but it was weak. Indeed, compared with trait means, plasticity was relatively unimportant for explaining differences in species commonness. Main conclusions Our results do not indicate that larger phenotypic plasticity of leaf morphological traits enhances species abundance. Furthermore, possession of a particular trait value, rather than of trait plasticity, is a more important determinant of species commonness.

Detection efficiency of microchannel plates for e(-) and pi(-) in the momentum range from 17.5 to 345 MeV/c

High-energy e(-) and pi(-) were measured by the multichannel plate (MCP) detector at the PiM1 beam line of the High Intensity Proton Accelerator Facilities located at the Paul Scherrer Institute, Villigen, Switzerland. The measurements provide the absolute detection efficiencies for these particles: 5.8% +/- 0.5% for electrons in the beam momenta range 17.5-300 MeV/c and 6.0% +/- 1.3% for pions in the beam momenta range 172-345 MeV/c. The pulse height distribution determined from the measurements is close to an exponential function with negative exponent, indicating that the particles penetrated the MCP material before producing the signal somewhere inside the channel. Low charge extraction and nominal gains of the MCP detector observed in this study are consistent with the proposed mechanism of the signal formation by penetrating radiation. A very similar MCP ion detector will be used in the Neutral Ion Mass (NIM) spectrometer designed for the JUICE mission of European Space Agency (ESA) to the Jupiter system, to perform measurements of the chemical composition of the Galilean moon exospheres. The detection efficiency for penetrating radiation determined in the present studies is important for the optimisation of the radiation shielding of the NIM detector against the high-rate and high-energy electrons trapped in Jupiter's magnetic field. Furthermore, the current studies indicate that MCP detectors can be useful to measure high-energy particle beams at high temporal resolution. (C) 2015 AIP Publishing LLC.