Carbon to oxygen ratios in extrasolar planetesimals

Observations of small extrasolar planets with a wide range of densities imply a variety of planetary compositions and structures. Currently, the only technique to measure the bulk composition of extrasolar planetary systems is the analysis of planetary debris accreting on to white dwarfs, analogous to abundance studies of meteorites. We present measurements of the carbon and oxygen abundances in the debris of planetesimals at ten white dwarfs observed with the Hubble Space Telescope, along with C/O ratios of debris in six systems with previously reported abundances. We find no evidence for carbon-rich planetesimals, with C/O ) = −0.92, and oxygen-rich objects with C/O less than or equal to that of the bulk Earth. The latter group may have a higher mass fraction of water than the Earth, increasing their relative oxygen abundance

How certain are greenhouse gas reductions from bioenergy? Life cycle assessment and uncertainty analysis of wood pellet-to-electricity supply chains from forest residues

Climate change and energy policies often encourage bioenergy as a sustainable greenhouse gas (GHG) reduction option. Recent research has raised concerns about the climate change impacts of bioenergy as heterogeneous pathways of producing and converting biomass, indirect impacts, uncertainties within the bioenergy supply chains and evaluation methods generate large variation in emission profiles. This research examines the combustion of wood pellets from forest residues to generate electricity and considers uncertainties related to GHG emissions arising at different points within the supply chain. Different supply chain pathways were investigated by using life cycle assessment (LCA) to analyse the emissions and sensitivity analysis was used to identify the most significant factors influencing the overall GHG balance. The calculations showed in the best case results in GHG reductions of 83% compared to coal-fired electricity generation. When parameters such as different drying fuels, storage emission, dry matter losses and feedstock market changes were included the bioenergy emission profiles showed strong variation with up to 73% higher GHG emissions compared to coal. The impact of methane emissions during storage has shown to be particularly significant regarding uncertainty and increases in emissions. Investigation and management of losses and emissions during storage is therefore key to ensuring significant GHG reductions from biomass

Which industries are served by online marketplaces for technology?

This study investigates a recent phenomenon in the market for technology: online marketplaces for technological inventions, which support the listing, search, and exchange of technological inventions by sellers and buyers. Focusing on three salient theoretical factors that affect markets for technology – search costs, ambiguity about the underlying knowledge and its applications, and expropriation concerns – our research systematically explores which industries are served by online marketplaces. We exploit the fact that the magnitude of these factors varies across industries and identify key features of online marketplaces that may address these factors. Our proprietary dataset covers 12 online marketplaces for technology and spans over 140 industries. The results indicate that online marketplaces are more likely to serve an industry with (a) a higher cost of searching for technologies in that industry, (b) greater ambiguity about the underlying technology’s potential applications across industries, and (c) greater ability to protect inventions from expropriation

Processing-structure-property relationship in fused filament fabrication of Nylon-12

This thesis is devoted to the investigation of the structure-property-relationships in additive manufacturing (AM). General thermodynamic and kinetic aspects that are peculiar for this manufacturing mode are considered, and made specific and applied by selecting a particular flavour of AM (FFF) and material (Nylon-12). Fused Filament Fabrication (FFF) is an extrusion-based additive manufacturing method for thermoplastic polymers. Nylon-12 is a semi-crystalline thermoplastic polymer that is one of the most commonly used materials in FFF. The FFF process results in a unique spatially dependent thermal history, which has a considerable effect on the resultant microstructure. Crystallisation within the polymer proceeds via temperature-dependent nucleation and growth. In turn, the crystal structure relates to and determines the mechanical properties in semi-crystalline polymers. This relationship can be referred to as the processing-structure-property relationship. This thesis focuses on a specific area of this relationship in FFF Nylon-12. These focused areas are the effect of the thermal history on the development of crystal morphology in Nylon-12 and degree of crystallinity, and the subsequent effect of the degree of crystallinity on tensile properties. Precise control has not yet been achieved over the properties of FFF samples, which has provided a considerable barrier to industry adoption. Additionally, there have been comparatively few studies on Nylon-12 in the context of FFF compared to other polymeric materials, despite its extensive use in FFF. The aim of this thesis, therefore, is to build a quantitative link between thermal history, degree of crystallinity and tensile properties in Nylon-12 which can be used to provide more precise control and the ability to tailor the properties of FFF samples. In situ X-ray diffraction was performed on FFF Nylon-12 samples, revealing that the orientation resulting from extrusion leads to a particular temperature-dependent crystal structure. Slower cooling rates from the melt were shown to result in a higher degree of crystallinity and higher lamellar density. It was shown that the thermal conditions during FFF lead to formation of the γ-form crystal structure, but with crystal structure differing from cast, sintered or moulded Nylon-12. A model of structural evolution was proposed to explain these observations. The thermal properties of Nylon-12 filament and FFF samples produced under different processing conditions were examined through Differential Scanning Calorimetry (DSC). It was found that Nylon-12 crystallises optimally at temperatures above 150 °C. Slower cooling rates and higher annealing temperatures were shown to result in a higher degree of crystallinity and more perfectly formed crystal structure. The processing-structure relationship between processing conditions and the degree of crystallinity was analysed. A model of the crystallisation behaviour was constructed based on this data. An alternative fit to model crystallisation behaviour was proposed, which has the ability to make quantitative predictions about evolution of crystallinity and rate of crystallisation based on thermal history. Tensile testing of FFF-produced Nylon-12 samples revealed the relationships between processing conditions and tensile properties, specifically Young’s Modulus, ultimate tensile strength, yield point and elongation at break. These data sets were fitted with a quantitative relationship. Finally, governing equations for the processing-structure-property relationship for FFF Nylon-12 were proposed based on the collected body of data. This thesis sheds light on the processing-structure-property relationship in FFF Nylon-12, providing a full link from processing conditions to the mechanical properties. Additionally, the analysis and modelling of crystallisation behaviour has allowed for the data to be well-fitted to a set of governing equations that allow the prediction of tensile behaviour across a wider set of processing conditions. The methodology proposed, developed and used in this thesis provides the basis for further investigation into other components of the processing-structure-property relationship in Nylon-12, or for building similar relationships for other semi-crystalline thermoplastic polymers. Moreover, the present framework can be extended to other AM modalities, e.g., laser-based fabrication. This new understanding can lead to tailoring of structural and mechanical properties via alteration of the thermal history, eliminating the need for trial and error in AM and improving its performance compared to other manufacturing methods.</p

The RANO Leptomeningeal Metastasis Group proposal to assess response to treatment: lack of feasibility and clinical utility and a revised proposal : Lack of feasibility and clinical utility and a revised proposal

BACKGROUND: A scorecard to evaluate magnetic resonance imaging (MRI) findings during the course of leptomeningeal metastases (LM) has been proposed by the Response Assessment in Neuro-Oncology (RANO) group. METHODS: To explore the feasibility of the Leptomeningeal Assessment in Neuro-Oncology (LANO) scorecard, cerebrospinal MRIs of 22 patients with LM from solid tumors were scored by 10 neuro-oncologists and 9 neuroradiologists at baseline and at follow-up after treatment. Raters were blinded for clinical data including treatment. Agreement between raters of single items was evaluated using a Krippendorff alpha coefficient. Agreement between numerical parameters such as scores for changes between baseline and follow-up and total scores was evaluated by determining the intraclass coefficient of correlation. RESULTS: Most raters experienced problems with the instructions of the scorecard. No acceptable alpha concordance coefficient was obtained for the rating of single items at baseline or follow-up. The most concordant ratings were obtained for spinal nodules. The concordances were worst for brain linear leptomeningeal enhancement and cranial nerve enhancement. Discordance was less prominent among neuroradiologists than among neuro-oncologists. High variability was also observed for evaluating changes between baseline and follow-up and for total scores. CONCLUSIONS: Assessing response of LM by MRI remains challenging. Central imaging review is therefore indispensable for clinical trials. Based on the present results, we propose a new, simplified scorecard that will require validation using a similar approach as pursued here. The main challenges are to define measurable versus nonmeasurable (target) lesions and measures of change that allow assessment of response

Supplementary Material for: Adoption Patterns of Bronchoscopic Lung Volume Reduction Procedures in Germany and Predicted Procedure Volumes for Other European Countries

Background: Bronchoscopic lung volume reduction (BLVR) using valves and coils has been approved for use since 2003 and 2010, respectively. Objective(s): To study adoption patterns of BLVR in an early-adopting country, and to estimate potential treatment volumes in other European countries. Methods: Therapy- and age-specific volumes for endobronchial valve and coil procedures were obtained from German federal statistics for 2007–2016. Therapy-specific and total BLVR procedure volumes and growth were computed, and patterns in treatment age and device utilization analyzed. Patient volumes for other European countries were predicted using mean German patient volumes of the last 3 data years and age-specific population and emphysema incidences. Results: Over the study period, annual BLVR procedure volumes grew from 91 to 2,053 (+2,256%), reaching a peak of 2,556 procedures in 2013. Coil procedures constituted 36% of the total volume in 2016. Treatment age was stable over time, with highest procedure counts in age group 60–64 years for valves and 65–69 years for coils. A limited increase in device use per procedure was observed. For Germany, 1,655 newly treated BLVR patients were estimated per year, approximating about 5% of the annual newly diagnosed severe emphysema cases. Predicted volume estimates for other European countries ranged from 1 for Liechtenstein to 1,226 for France. Conclusions: Analysis of German procedure data show pronounced BLVR therapy uptake in the early years of adoption, with the more recently introduced coil therapy used in about one-third of patients. Estimated patient volumes to date constitute only a small fraction of the severe emphysema population