Measurement report: Sulfuric acid nucleation and experimental conditions in a photolytic flow reactor

Nucleation rates involving sulfuric acid and water measured in a photolytic flow reactor have decreased considerably over a time period of several years. Results show that the system flow reactor, gas supplies and lines, flow meters, valves, H2SO4 photo-oxidant sources has reached a baseline stability that yields nucleation information such as cluster free energies. The baseline nucleation rate is punctuated by temporary bursts that in many instances are linked to cylinder changes, delineating this source of potential contaminants. Diagnostics were performed to better understand the system, including growth studies to assess H2SO4 levels, chemiluminescent NO and NOx detection to assess the HONO source, and deployment of a second particle detector to assess the nanoparticle detection system. The growth of seed particles shows trends consistent with the sizes of nucleated particles and provides an anchor for calculated H2SO4 concentrations. The chemiluminescent detector revealed that small amounts of NO are present in the HONO source, 10% of HONO. The second condensation-Type particle counter indicates that the nanoparticle mobility sizing system has a bias at low sulfuric acid levels. The measured and modeled nucleation rates represent upper limits to nucleation in the binary homogeneous system, H2SO4-H2O, as contaminants might act to enhance nucleation rates and ion-mediated nucleation may contribute. Nonetheless, the experimental nucleation rates, which have decreased by an order of magnitude or larger since our first publication, extrapolate to some of the lowest rates reported in experiments with photolytic H2SO4. Results from experiments with varying water content and with ammonia addition are also presented and have also decreased by an order of magnitude from our previous work; revised energetics of clusters in this three-component system are derived which differ from our previous energetics mainly in the five-Acid and larger clusters

Paradigms for Creating Activities that Integrate Mathematics and Science Topics

Research has shown that undergraduate students benefit from seeing examples of mathematics applied to real-world situations. This article describes three different paradigms for how math and discipline partner faculty worked together to create mathematical activities that illustrate applications of the topics being studied in precalculus and calculus. All three examples are discussed within the framework of PDSA cycles to describe the process by which the teams collaborated to plan, enact, study, and refine their lessons. Findings discuss both the difficulties of creating integrated activities (differences in terms and definitions between math and science faculty, different foregrounding of math versus science among faculty), and the value of the resultant lessons, such as increased level of student engagement, higher cognitive demand, and the role that relevant applications can play in piquing student interest in STEM

Fishbowl Discussions: Promoting Collaboration between Mathematics and Partner Disciplines

A National Consortium for Synergistic Undergraduate Mathematics via Multi-institutional Interdisciplinary Teaching Partnerships project (SUMMIT-P) is a collaboration of institutions focused on revising first- and second-year mathematics courses with the help of partner disciplines with prerequisite mathematics courses. This paper describes the fishbowl discussion technique used by the consortium members to encourage interdisciplinary conversation. Vignettes describing the results of conversations that occurred at several consortium member institutions are provided by the co-authors

Fishbowl Discussions: Promoting Collaboration between Mathematics and Partner Disciplines

A National Consortium for Synergistic Undergraduate Mathematics via Multi-institutional Interdisciplinary Teaching Partnerships project (SUMMIT-P) is a collaboration of institutions focused on revising first- and second-year mathematics courses with the help of partner disciplines with prerequisite mathematics courses. This paper describes the fishbowl discussion technique used by the consortium members to encourage interdisciplinary conversation. Vignettes describing the results of conversations that occurred at several consortium member institutions are provided by the co-authors

Rapamycin Response in Tumorigenic and Non-Tumorigenic Hepatic Cell Lines

The mTOR inhibitor rapamycin has anti-tumor activity across a variety of human cancers, including hepatocellular carcinoma. However, resistance to its growth inhibitory effects is common. We hypothesized that hepatic cell lines with varying rapamycin responsiveness would show common characteristics accounting for resistance to the drug.We profiled a total of 13 cell lines for rapamycin-induced growth inhibition. The non-tumorigenic rat liver epithelial cell line WB-F344 was highly sensitive while the tumorigenic WB311 cell line, originally derived from the WB-F344 line, was highly resistant. The other 11 cell lines showed a wide range of sensitivities. Rapamycin induced inhibition of cyclin E-dependent kinase activity in some cell lines, but the ability to do so did not correlate with sensitivity. Inhibition of cyclin E-dependent kinase activity was related to incorporation of p27(Kip1) into cyclin E-containing complexes in some but not all cell lines. Similarly, sensitivity of global protein synthesis to rapamycin did not correlate with its anti-proliferative effect. However, rapamycin potently inhibited phosphorylation of two key substrates, ribosomal protein S6 and 4E-BP1, in all cases, indicating that the locus of rapamycin resistance was downstream from inhibition of mTOR Complex 1. Microarray analysis did not disclose a unifying mechanism for rapamycin resistance, although the glycolytic pathway was downregulated in all four cell lines studied.We conclude that the mechanisms of rapamycin resistance in hepatic cells involve alterations of signaling downstream from mTOR and that the mechanisms are highly heterogeneous, thus predicting that maintaining or promoting sensitivity will be highly challenging

Risk and predictors of dementia and parkinsonism in idiopathic REM sleep behaviour disorder: a multicentre study

Idiopathic REM sleep behaviour disorder (iRBD) is a powerful early sign of Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. This provides an unprecedented opportunity to directly observe prodromal neurodegenerative states, and potentially intervene with neuroprotective therapy. For future neuroprotective trials, it is essential to accurately estimate phenoconversion rate and identify potential predictors of phenoconversion. This study assessed the neurodegenerative disease risk and predictors of neurodegeneration in a large multicentre cohort of iRBD. We combined prospective follow-up data from 24 centres of the International RBD Study Group. At baseline, patients with polysomnographically-confirmed iRBD without parkinsonism or dementia underwent sleep, motor, cognitive, autonomic and special sensory testing. Patients were then prospectively followed, during which risk of dementia and parkinsonsim were assessed. The risk of dementia and parkinsonism was estimated with Kaplan-Meier analysis. Predictors of phenoconversion were assessed with Cox proportional hazards analysis, adjusting for age, sex, and centre. Sample size estimates for disease-modifying trials were calculated using a time-to-event analysis. Overall, 1280 patients were recruited. The average age was 66.3 \ub1 8.4 and 82.5% were male. Average follow-up was 4.6 years (range = 1-19 years). The overall conversion rate from iRBD to an overt neurodegenerative syndrome was 6.3% per year, with 73.5% converting after 12-year follow-up. The rate of phenoconversion was significantly increased with abnormal quantitative motor testing [hazard ratio (HR) = 3.16], objective motor examination (HR = 3.03), olfactory deficit (HR = 2.62), mild cognitive impairment (HR = 1.91-2.37), erectile dysfunction (HR = 2.13), motor symptoms (HR = 2.11), an abnormal DAT scan (HR = 1.98), colour vision abnormalities (HR = 1.69), constipation (HR = 1.67), REM atonia loss (HR = 1.54), and age (HR = 1.54). There was no significant predictive value of sex, daytime somnolence, insomnia, restless legs syndrome, sleep apnoea, urinary dysfunction, orthostatic symptoms, depression, anxiety, or hyperechogenicity on substantia nigra ultrasound. Among predictive markers, only cognitive variables were different at baseline between those converting to primary dementia versus parkinsonism. Sample size estimates for definitive neuroprotective trials ranged from 142 to 366 patients per arm. This large multicentre study documents the high phenoconversion rate from iRBD to an overt neurodegenerative syndrome. Our findings provide estimates of the relative predictive value of prodromal markers, which can be used to stratify patients for neuroprotective trials