Toric partial density functions and stability of toric varieties

Let $(L, h)\to (X, \omega)$ denote a polarized toric K\"ahler manifold. Fix a toric submanifold $Y$ and denote by $\hat{\rho}_{tk}:X\to \mathbb{R}$ the partial density function corresponding to the partial Bergman kernel projecting smooth sections of $L^k$ onto holomorphic sections of $L^k$ that vanish to order at least $tk$ along $Y$, for fixed $t>0$ such that $tk\in \mathbb{N}$. We prove the existence of a distributional expansion of $\hat{\rho}_{tk}$ as $k\to \infty$, including the identification of the coefficient of $k^{n-1}$ as a distribution on $X$. This expansion is used to give a direct proof that if $\omega$ has constant scalar curvature, then $(X, L)$ must be slope semi-stable with respect to $Y$. Similar results are also obtained for more general partial density functions. These results have analogous applications to the study of toric K-stability of toric varieties.Comment: Accepted by Mathematische Annalen on 13 September 201

Balancing evolving logics: business model change in the Leibniz research museums

This study shows how stakeholders’ evolving logics drive business model change over time. Using secondary data from the Leibniz research museums in Germany in a longitudinal content analysis, we relate logics as drivers of business model change in a context that is shaped by the interests of multiple stakeholder groups. Our findings illustrate how stakeholders’ varying emphases on economic, cultural and political logics affect the content, structure and governance of the activities constituting the business models of the research museums. They lead to an increasing need for the demonstration of value creation and the identification of new sources of revenue. The strength of the impact of these logics depends on the individual abilities of the research museums to bargain for their business models. Overall, our study sheds light on the drivers of business model change in public organizations and the accompanying macro-level factors in the German science system

Association of lung clearance index with survival in individuals with cystic fibrosis.

BACKGROUND The lung clearance index (LCI) assesses global ventilation inhomogeneity and is a sensitive biomarker of airway function in cystic fibrosis (CF) lung disease. OBJECTIVES We examined the association of LCI with the risk of death or lung transplantation (LTX) in individuals with CF. METHODS We performed a retrospective analysis in a cohort of individuals with CF aged≥5 years with LCI and FEV1 measurements performed between 1980 and 2006. The outcome was time until death or LTX. We used the earliest available LCI and FEV1 values in a Cox proportional hazard regression adjusted for demographic and clinical variables. For sensitivity analyses, we used the mean of the first three LCI and FEV1 measurements, stratified the cohort based on age, and investigated individuals with normal FEV1. RESULTS In total, 237 individuals with CF with a mean (range) age of 13.9 (5.6-41.0) years were included. The time-to-event analysis accrued 3813 person-years and 94 (40%) individuals died or received LTX. Crude hazard ratios [95% CI] were 1.04 [1.01-1.06] per one z-score increase in LCI and 1.25 [1.11-1.41] per one z-score decrease in FEV1. After adjusting LCI and FEV1 mutually in addition to sex, age, BMI and the number of hospitalisations, hazard ratios were 1.04 [1.01-1.07] for LCI, and 1.12 [0.95-1.33] for FEV1. Sensitivity analyses yielded similar results and using the mean LCI strengthened the associations. CONCLUSIONS Increased ventilation inhomogeneity is associated with greater risk of death or LTX. Our data support LCI as novel surrogate of survival in individuals with CF

Hybrid Targeted/Untargeted Screening Method for the Determination of Wildfire and Water-Soluble Organic Tracers in Ice Cores and Snow.

Wildfires can influence the earth's radiative forcing through the emission of biomass-burning aerosols. To better constrain the impacts of wildfires on climate and understand their evolution under future climate scenarios, reconstructing their chemical nature, assessing their past variability, and evaluating their influence on the atmospheric composition are essential. Ice cores are unique to perform such reconstructions representing archives not only of past biomass-burning events but also of concurrent climate and environmental changes. Here, we present a novel methodology for the quantification of five biomass-burning proxies (syringic acid, vanillic acid, vanillin, syringaldehyde, and p-hydroxybenzoic acid) and one biogenic emission proxy (pinic acid) using solid phase extraction (SPE) and ultrahigh-performance liquid chromatography coupled with high-resolution mass spectrometry. This method was also optimized for untargeted screening analysis to gain a broader knowledge about the chemical composition of organic aerosols in ice and snow samples. The method provides low detection limits (0.003-0.012 ng g-1), high recoveries (74 ± 10%), and excellent reproducibility, allowing the quantification of the six proxies and the identification of 313 different molecules, mainly constituted by carbon, hydrogen, and oxygen. The effectiveness of two different sample storage strategies, i.e., re-freezing of previously molten ice samples and freezing of previously loaded SPE cartridges, was also assessed, showing that the latter approach provides more reproducible results

Age and body mass index affect fit of spirometry Global Lung Function Initiative references in schoolchildren

BACKGROUND: References from the Global Lung Function Initiative (GLI) are widely used to interpret children's spirometry results. We assessed fit for healthy schoolchildren. METHODS: LuftiBus in the School was a population-based cross-sectional study undertaken in 2013-2016 in the canton of Zurich, Switzerland. Parents and their children aged 6-17 years answered questionnaires about respiratory symptoms and lifestyle. Children underwent spirometry in a mobile lung function lab. We calculated GLI-based z-scores for forced expiratory volume in 1 s (FEV$_{1}$), forced vital capacity (FVC), FEV$_{1}$/FVC and forced expiratory flow for 25-75% of FVC (FEF$_{25-75}$) for healthy White participants. We defined appropriate fit to GLI references by mean values between +0.5 and -0.5 z-scores. We assessed whether fit varied by age, body mass index, height and sex using linear regression models. RESULTS: We analysed data from 2036 children with valid FEV$_{1}$ measurements, of whom 1762 also had valid FVC measurements. The median age was 12.2 years. Fit was appropriate for children aged 6-11 years for all indices. In adolescents aged 12-17 years, fit was appropriate for FEV$_{1}$/FVC z-scores (mean±sd -0.09±1.02), but not for FEV$_{1}$ (-0.62±0.98), FVC (-0.60±0.98) and FEF$_{25-75}$ (-0.54±1.02). Mean FEV$_{1}$, FVC and FEF$_{25-75}$ z-scores fitted better in children considered overweight (-0.25, -0.13 and -0.38, respectively) than normal weight (-0.55, -0.50 and -0.55, respectively; p-trend <0.001, 0.014 and <0.001, respectively). FEV$_{1}$, FVC and FEF$_{25-75}$ z-scores depended on both age and height (p-interaction 0.033, 0.019 and <0.001, respectively). CONCLUSION: GLI-based FEV$_{1}$, FVC, and FEF$_{25-75}$ z-scores do not fit White Swiss adolescents well. This should be considered when using reference equations for clinical decision-making, research and international comparison

Age and body mass index affect fit of spirometry Global Lung Function Initiative references in schoolchildren.

Background References from the Global Lung Function Initiative (GLI) are widely used to interpret children's spirometry results. We assessed fit for healthy schoolchildren. Methods LuftiBus in the School was a population-based cross-sectional study undertaken in 2013-2016 in the canton of Zurich, Switzerland. Parents and their children aged 6-17 years answered questionnaires about respiratory symptoms and lifestyle. Children underwent spirometry in a mobile lung function lab. We calculated GLI-based z-scores for forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), FEV1/FVC and forced expiratory flow for 25-75% of FVC (FEF25-75) for healthy White participants. We defined appropriate fit to GLI references by mean values between +0.5 and -0.5 z-scores. We assessed whether fit varied by age, body mass index, height and sex using linear regression models. Results We analysed data from 2036 children with valid FEV1 measurements, of whom 1762 also had valid FVC measurements. The median age was 12.2 years. Fit was appropriate for children aged 6-11 years for all indices. In adolescents aged 12-17 years, fit was appropriate for FEV1/FVC z-scores (mean±sd -0.09±1.02), but not for FEV1 (-0.62±0.98), FVC (-0.60±0.98) and FEF25-75 (-0.54±1.02). Mean FEV1, FVC and FEF25-75 z-scores fitted better in children considered overweight (-0.25, -0.13 and -0.38, respectively) than normal weight (-0.55, -0.50 and -0.55, respectively; p-trend <0.001, 0.014 and <0.001, respectively). FEV1, FVC and FEF25-75 z-scores depended on both age and height (p-interaction 0.033, 0.019 and <0.001, respectively). Conclusion GLI-based FEV1, FVC, and FEF25-75 z-scores do not fit White Swiss adolescents well. This should be considered when using reference equations for clinical decision-making, research and international comparison

Agreement of parent- and child-reported wheeze and its association with measurable asthma traits

Objectives In epidemiological studies, childhood asthma is usually assessed with questionnaires directed at parents or children, and these may give different answers. We studied how well parents and children agreed when asked to report symptoms of wheeze and investigated whose answers were closer to measurable traits of asthma. Methods LuftiBus in the school is a cross-sectional survey of respiratory health among Swiss schoolchildren aged 6–17 years. We applied questionnaires to parents and children asking about wheeze and exertional wheeze in the past year. We assessed agreement between parent–child answers with Cohen's kappa (k), and associations of answers from children and parents with fractional exhaled nitric oxide (FeNO) and forced expiratory volume in 1 s over forced vital capacity (FEV1/FVC), using quantile regression. Results We received questionnaires from 3079 children and their parents. Agreement was poor for reported wheeze (k = 0.37) and exertional wheeze (k = 0.36). Median FeNO varied when wheeze was reported by children (19 ppb, interquartile range [IQR]: 9–44), parents (22 ppb, IQR: 12–46), both (31 ppb, IQR: 16–55), or neither (11 ppb, IQR: 7–19). Median absolute FEV1/FVC was the same when wheeze was reported by children (84%, IQR: 78–89) and by parents (84%, IQR: 78–89), lower when reported by both (82%, IQR: 78–87), and higher when reported by neither (87%, IQR: 82–91). For exertional wheeze findings were similar. Results did not differ by age or sex. Conclusion Our findings suggest that surveying both parents and children and combining their responses can help us to better identify children with measurable asthma traits

Evaluation of the double-tracer gas single-breath washout test in a pediatric field study.

BACKGROUND The early-life origins of chronic pulmonary diseases are thought to arise in peripheral small airways. Predictors of ventilation inhomogeneity, a proxy of peripheral airway function, are understudied in schoolchildren. RESEARCH QUESTION Is the double-tracer gas single-breath washout (DTG-SBW) measurement feasible in a pediatric field study setting? What are the predictors of the DTG-SBW derived ventilation inhomogeneity estimate in unselected schoolchildren? STUDY DESIGN AND METHODS In this prospective cross-sectional field study, a mobile lung function-testing unit visited participating schools in Switzerland. We applied DTG-SBW, fraction of exhaled nitric oxide (FeNO), and spirometry measurements. The DTG-SBW is based on tidal inhalation of helium (He) and sulfur-hexafluoride (SF6) and the phase III slope (SIIIHe-SF6) is derived. We assessed feasibility, repeatability, and associations of SIIIHe-SF6 with the potential predictors anthropometrics, presence of wheeze (i.e. parental report of ≥ 1 episode of wheeze in the prior year), FeNO, forced expiratory volume in the first second (FEV1), and FEV1/forced vital capacity (FVC). RESULTS In 1782 children, 5223 DTG-SBW trials were obtained. The DTG-SBW was acceptable in 1449 (81.3%) children, coefficient of variation was 39.8%. SIIIHe-SF6 was independently but weakly positively associated with age and BMI. In 276 (21.2%) children, wheeze was reported. SIIIHe-SF6 was higher by 0.049 g.mol.L-1 in children with wheeze as compared to those without and remained associated with wheeze after adjusting for age and BMI in a multi-variable linear regression model. SIIIHe-SF6 was not associated with FeNO, FEV1, and FEV1/FVC. INTERPRETATION The DTG-SBW is feasible in a pediatric field study setting. On the population level, age, body composition and wheeze are independent predictors of peripheral airway function in unselected schoolchildren. The variation of the DTG-SBW possibly constrains its current applicability on the individual level