Online molecular characterisation of organic aerosols in an atmospheric chamber using extractive electrospray ionisation mass spectrometry

Abstract. The oxidation of biogenic volatile organic compounds (VOCs) represents a substantial source of secondary organic aerosol (SOA) in the atmosphere. In this study, we present online measurements of the molecular constituents formed in the gas and aerosol phases during α-pinene oxidation in the Cambridge Atmospheric Simulation Chamber (CASC). We focus on characterising the performance of extractive electrospray ionisation (EESI) mass spectrometry (MS) for particle analysis. A number of new aspects of EESI-MS performance are considered here. We show that relative quantification of organic analytes can be achieved in mixed organic–inorganic particles. A comprehensive assignment of mass spectra for α-pinene derived SOA in both positive and negative ion modes is obtained using an ultra-high-resolution mass spectrometer. We compare these online spectra to conventional offline ESI-MS spectra and find good agreement in terms of the compounds identified, without the need for complex sample work-up procedures. Under our experimental conditions, EESI-MS signals arise only from particle-phase analytes. High-time-resolution (7 min) EESI-MS spectra are compared with simulations from the near-explicit Master Chemical Mechanism (MCM) for a range of reaction conditions. We show that MS peak abundances scale with modelled concentrations for condensable products (pinonic acid, pinic acid, OH-pinonic acid). Relative quantification is achieved throughout SOA formation as the composition, size and mass (5–2400 µg m−3) of particles is evolving. This work provides a robust demonstration of the advantages of EESI-MS for chamber studies over offline ESI-MS (time resolution, relative quantification) and over hard online techniques (molecular information). </jats:p

Clinicians' views of using cortical auditory evoked potentials (CAEP) in the permanent childhood hearing impairment patient pathway

Objective: To obtain clinicians' views on the use of cortical auditory evoked potentials (CAEP) in the clinical pathway. Design: A questionnaire aimed at clinicians who use the HEARLab system with the Aided Cortical Assessment (ACA) Module. Results compared for Australians (where HEARLab produced) to other countries. Sample: The questionnaire was completed by 49 clinicians; 33 from Australia and 13 clinicians outside of Australia and 3 clinicians, destination unknown. Results: The findings of this research demonstrated that clinicians using CAEPs found them valuable for clinical practice. CAEPs were used to verify or modify hearing aid fittings and were used for counselling parents to reinforce the need for hearing aids. With the use of speech token as the stimulus clinicians had more relevant information to increase confidence in decision-making on paediatric hearing management. Conclusions: The main benefit from the use of CAEPs (using speech token stimuli) was for infant hearing aid fitting programmes, to facilitate earlier decisions relating to hearing aid fitting, for fine-tuning the aids and as an additional measure for cochlear implant referrals

Strategies for Developing Sustainable Design Practice for Students and SME Professionals

Designers and engineers seem finally to be awakening to the challenge that sustainable development has given. Educators and students alike are keenly aware of the need to become more effective in the training and practice of their specific disciplines with respect to sustainability. \noindent In the past four years since this research has developed, there has been a marked change in the mass market appeal for sustainable products and services. Implementation of sustainable design practice from both recent graduates and also innovative small and medium enterprises (SMEs) at a local level is slow. One would assume that the consumer drive would push a change in design practice but perhaps the complexities of sustainable design along with the lack of experience in the field are providing barriers to designers and marketers alike. In addition the SME sector alone makes up the bulk of industry within the European Union (EU) varying in some countries from 80-95% of the total numbers of companies (Tukker et al. 2000). These industries by their nature find it difficult to dedicate expertise solely to sustainable development issues. The strategy outlined in this paper intended to introduce concepts of sustainable design thinking and practice to both SMEs and undergraduate students. \noindent This current and ongoing research qualitatively assesses appropriate models for educating for sustainable design thinking with SME employees and undergraduate design students. The sample groups include Industrial Design and Product Design undergraduate students in Ireland at the Institute of Technology, Carlow (IT Carlow), The University of Limerick (UL) and a sample of SMEs in the South East of Ireland, with broad national participation from other students of design and professionals from industry. Current levels of understanding of students and SME professionals of key environmental and social issues are measured

Learning intrinsic excitability in medium spiny neurons

We present an unsupervised, local activation-dependent learning rule for intrinsic plasticity (IP) which affects the composition of ion channel conductances for single neurons in a use-dependent way. We use a single-compartment conductance-based model for medium spiny striatal neurons in order to show the effects of parametrization of individual ion channels on the neuronal activation function. We show that parameter changes within the physiological ranges are sufficient to create an ensemble of neurons with significantly different activation functions. We emphasize that the effects of intrinsic neuronal variability on spiking behavior require a distributed mode of synaptic input and can be eliminated by strongly correlated input. We show how variability and adaptivity in ion channel conductances can be utilized to store patterns without an additional contribution by synaptic plasticity (SP). The adaptation of the spike response may result in either "positive" or "negative" pattern learning. However, read-out of stored information depends on a distributed pattern of synaptic activity to let intrinsic variability determine spike response. We briefly discuss the implications of this conditional memory on learning and addiction.Comment: 20 pages, 8 figure

Highest weight Macdonald and Jack Polynomials

Fractional quantum Hall states of particles in the lowest Landau levels are described by multivariate polynomials. The incompressible liquid states when described on a sphere are fully invariant under the rotation group. Excited quasiparticle/quasihole states are member of multiplets under the rotation group and generically there is a nontrivial highest weight member of the multiplet from which all states can be constructed. Some of the trial states proposed in the literature belong to classical families of symmetric polynomials. In this paper we study Macdonald and Jack polynomials that are highest weight states. For Macdonald polynomials it is a (q,t)-deformation of the raising angular momentum operator that defines the highest weight condition. By specialization of the parameters we obtain a classification of the highest weight Jack polynomials. Our results are valid in the case of staircase and rectangular partition indexing the polynomials.Comment: 17 pages, published versio

The c-Myc Oncoprotein Interacts with Bcr

AbstractBcr is a multifunctional protein that is the fusion partner for Abl (p210 Bcr-Abl) in Philadelphia chromosome positive leukemias. We have identified c-Myc as a binding partner for Bcr in both yeast and mammalian cells. We are also able to observe interactions between natively expressed c-Myc and Bcr in leukemic cell lines. Although Bcr and Max have overlapping binding sites on c-Myc, Bcr cannot interact with Max, or with the c-Myc•Max heterodimer. Bcr expression blocks activation of c-Myc-responsive genes, as well as the transformed phenotype induced by coexpression of c-Myc and H-Ras, and this finding suggests that one function of Bcr is to limit the activity of c-Myc. However, Bcr does not block c-Myc function by preventing its nuclear localization. Interestingly, increased Bcr dosage in COS-7 and K-562 cells correlates with a reduction in c-Myc protein levels, suggesting that Bcr may in fact be limiting c-Myc activity by regulating its stability. These data indicate that Bcr is a novel regulator of c-Myc function whose disrupted expression may contribute to the high level of c-Myc protein that is observed in Bcr-Abl transformed cells

Measurements of polarized photo-pion production on longitudinally polarized HD and Implications for Convergence of the GDH Integral

We report new measurements of inclusive pion production from frozen-spin HD for polarized photon beams covering the Delta(1232) resonance. These provide data simultaneously on both H and D with nearly complete angular distributions of the spin-difference cross sections entering the Gerasimov-Drell-Hearn (GDH) sum rule. Recent results from Mainz and Bonn exceed the GDH prediction for the proton by 22 microbarns, suggesting as yet unmeasured high-energy components. Our pi0 data reveal a different angular dependence than assumed in Mainz analyses and integrate to a value that is 18 microbarns lower, suggesting a more rapid convergence. Our results for deuterium are somewhat lower than published data, considerably more precise and generally lower than available calculations.Comment: 4 pages, 4 figures. Submitted for publication in Physical Review Letter

Fabrication of CaO-NaO-SiO2/TiO2 Scaffolds for Surgical Applications

A series of titanium (Ti) based glasses were formulated (0.62 SiO2-0.14 Na2O-0.24 CaO, with 0.05 mol% TiO2 substitutions for SiO2) to develop glass/ceramic scaffolds for bone augmentation. Glasses were initially characterised using X-ray diffraction (XRD) and particle size analysis, where the starting materials were amorphous with 4.5 μm particles. Hot stage microscopy and high temperature XRD were used to determine the sintering temperature (̃700 °C) and any crystalline phases present in this region (Na2Ca3Si6O16, combeite and quartz). Hardness testing revealed that the Ti-free control (ScC- 2.4 GPa) had a significantly lower hardness than the Ti-containing materials (Sc1 and Sc2 ̃6.6 GPa). Optical microscopy determined pore sizes ranging from 544 to 955 lm. X-ray microtomography calculated porosity from 87 to 93 % and surface area measurements ranging from 2.5 to 3.3 SA/mm3. Cytotoxicity testing (using mesenchymal stem cells) revealed that all materials encouraged cell proliferation, particularly the higher Ti-containing scaffolds over 24-72 h. © Springer Science+Business Media, LLC 2012