Development and characterization of a single particle laser ablation mass spectrometer (SPLAM) for organic aerosol studies

A single particle instrument was developed for real-time analysis of organic aerosol. This instrument, named Single Particle Laser Ablation Mass Spectrometry (SPLAM), samples particles using an aerodynamic lens system for which the theoretical performances were calculated. At the outlet of this system, particle detection and sizing are realized by using two continuous diode lasers operating at λ = 403 nm. Polystyrene Latex (PSL), sodium chloride (NaCl) and dioctylphtalate (DOP) particles were used to characterize and calibrate optical detection of SPLAM. The optical detection limit (DL) and detection efficiency (DE) were determined using size-selected DOP particles. The DE ranges from 0.1 to 90% for 100 and 350 nm DOP particles respectively and the SPLAM instrument is able to detect and size-resolve particles as small as 110–120 nm. During optical detection, particle scattered light from the two diode lasers, is detected by two photomultipliers and the detected signals are used to trigger UV excimer laser (λ = 248 nm) used for one-step laser desorption ionization (LDI) of individual aerosol particles. The formed ions are analyzed by a 1 m linear time-of-flight mass spectrometer in order to access to the chemical composition of individual particles. The TOF-MS detection limit for gaseous aromatic compounds was determined to be 0.85 × 10<sup>−15</sup> kg (∼4 × 10<sup>3</sup> molecules). DOP particles were also used to test the overall operation of the instrument. The analysis of a secondary organic aerosol, formed in a smog chamber by the ozonolysis of indene, is presented as a first application of the instrument. Single particle mass spectra were obtained with an effective hit rate of 8%. Some of these mass spectra were found to be very different from one particle to another possibly reflecting chemical differences within the investigated indene SOA particles. Our study shows that an exhaustive statistical analysis, over hundreds of particles, and adapted reference mass spectra are further needed to understand the chemical meaning of single particle mass spectra of chemically complex submicrometer-sized organic aerosols

Protocol for an implementation and realist evaluation of a new organisational model for primary care practices in the canton of Vaud, Switzerland.

Continuity of care, especially for patients with complex needs, is a major challenge for healthcare systems in many high-income countries, including Switzerland. Since 2015, a collaborative project between Unisanté-Department of Family Medicine (DMF), some general practitioners (GPs) and canton of Vaud's public health authorities has sought to develop a new organisational model for the provision of primary care to ensure better care coordination and to provide adapted care deliveries to patients' healthcare needs. The model's main component is the addition of a primary care nurse to GPs practices. Three additional tools are individualised patient care plans, electronic medical records and patient empanelment. To assess this model, a 2-year pilot study has begun in nine GPs' practices in the canton. This paper presents the protocol for an evaluation of the implementation and effectiveness of the new organisational model. We will conduct a before-and-after study using a mixed-methods and a realist approach. First, we will use quantitative and qualitative data to assess the new organisational model's implementation (feasibility, fidelity, acceptability and costs) and effectiveness (healthcare services use, patient experience, staff experience and patient-level costs). Combining this data with focus group data will enable a realist evaluation of the pilot project, which will help understand the elements of context and mechanism that affect implementation. The evaluation will inform the canton of Vaud's health authorities about the limits of and perspectives for this organisational model. All results will also be made available to the practices and the patients involved. At the end of the project, we will propose organisational adaptations and a sustainable financial model for extending the model to other practices in the canton and potentially to the national level.The canton of Vaud's Human Research Ethics Committee approved the study, and Data Protection and Information Law Authority gave a favourable opinion concerning data processing procedures

Collision Dynamics and Solvation of Water Molecules in a Liquid Methanol Film

Environmental molecular beam experiments are used to examine water interactions with liquid methanol films at temperatures from 170 K to 190 K. We find that water molecules with 0.32 eV incident kinetic energy are efficiently trapped by the liquid methanol. The scattering process is characterized by an efficient loss of energy to surface modes with a minor component of the incident beam that is inelastically scattered. Thermal desorption of water molecules has a well characterized Arrhenius form with an activation energy of 0.47{\pm}0.11 eV and pre-exponential factor of 4.6 {\times} 10^(15{\pm}3) s^(-1). We also observe a temperature dependent incorporation of incident water into the methanol layer. The implication for fundamental studies and environmental applications is that even an alcohol as simple as methanol can exhibit complex and temperature dependent surfactant behavior.Comment: 8 pages, 5 figure

Gas- and particle-phase products from the photooxidation of acenaphthene and acenaphthylene by OH radicals

This work is focused on the gas-phase oxidation of acenaphthylene and acenaphthene by OH radicals and associated secondary organic aerosol (SOA) formation under low and high-NOx conditions. Experiments were carried out in an atmospheric simulation chamber using a proton transfer reaction time-of-flight-mass spectrometer (PTR-TOF-MS) and an aerosol time-of-flight-mass spectrometer (ATOFMS) to chemically characterize the gas- and particle-phase products, respectively. Due to the structures of these two aromatic compounds, the proposed chemical mechanisms exhibit some differences. In the case of acenaphthene, H-atom abstraction from the saturated cyclopenta-fused ring was found to be competitive with the OH-addition to the aromatic rings. During the photooxidation of acenaphthene using nitrous acid (HONO), aromatic ring-opening products such as indanone and indanone carbaldehyde, generated through OH addition to the aromatic ring, were formed in higher yields compared to low-NOx conditions. In the case of acenaphthylene, OH addition to the unsaturated cyclopenta-fused ring was strongly favored. Hence, ring-retaining species such as acenaphthenone and acenaphthenequinone, were identified as the main reaction products in both gas- and particle-phases, especially under high-NOx conditions. Subsequent SOA formation was observed in all experiments and SOA yields were determined under low/high-NOx conditions to be 0.61/0.46 and 0.68/0.55 from the OH-initiated oxidation of acenaphthylene and acenaphthene, respectively

Frame Theory for Signal Processing in Psychoacoustics

This review chapter aims to strengthen the link between frame theory and signal processing tasks in psychoacoustics. On the one side, the basic concepts of frame theory are presented and some proofs are provided to explain those concepts in some detail. The goal is to reveal to hearing scientists how this mathematical theory could be relevant for their research. In particular, we focus on frame theory in a filter bank approach, which is probably the most relevant view-point for audio signal processing. On the other side, basic psychoacoustic concepts are presented to stimulate mathematicians to apply their knowledge in this field

Rethinking the law and politics of democratic police accountability

This paper evaluates the work and impact of a number of Police and Crime Commissioners (PCCs) in England and Wales and attempts to refocus public discourse and scrutiny on their Police and Crime Plans as a key prism through which their performance should be measured. Drawing upon the literature published by various PCCs, the Stevens Commission, the Home Affairs Committee and numerous academics, the paper will argue that a major reform of democratic police accountability in England and Wales is needed. Due to the often voluminous and piecemeal nature of the documents published on the PCCs’ websites, the textual analysis is limited to the Police and Crime Plans for Greater Manchester, the West Midlands and the London Metropolitan are