Practical Considerations and Limitations of Using Leaf and Canopy Temperature Measurements as a Stomatal Conductance Proxy: Sensitivity across Environmental Conditions, Scale, and Sample Size.

Stomatal conductance (gs) is a crucial component of plant physiology, as it links plant productivity and water loss through transpiration. Estimating gs indirectly through leaf temperature (Tl) measurement is common for reducing the high labor cost associated with direct gs measurement. However, the relationship between observed Tl and gs can be notably affected by local environmental conditions, canopy structure, measurement scale, sample size, and gs itself. To better understand and quantify the variation in the relationship between Tl measurements to gs, this study analyzed the sensitivity of Tl to gs using a high-resolution three-dimensional model that resolves interactions between microclimate and canopy structure. The model was used to simulate the sensitivity of Tl to gs across different environmental conditions, aggregation scales (point measurement, infrared thermometer, and thermographic image), and sample sizes. Results showed that leaf-level sensitivity of Tl to gs was highest under conditions of high net radiation flux, high vapor pressure deficit, and low boundary layer conductance. The study findings also highlighted the trade-off between measurement scale and sample size to maximize sensitivity. Smaller scale measurements (e.g., thermocouple) provided maximal sensitivity because they allow for exclusion of shaded leaves and the ground, which have low sensitivity. However, large sample sizes (up to 50 to 75) may be needed to differentiate genotypes. Larger-scale measurements (e.g., thermal camera) reduced sample size requirements but include low-sensitivity elements in the measurement. This work provides a means of estimating leaf-level sensitivity and offers quantitative guidance for balancing scale and sample size issues.

Quantifying water-use efficiency in plant canopies with varying leaf angle and density distribution.

BACKGROUND AND AIMS: Variation in architectural traits related to the spatial and angular distribution of leaf area can have considerable impacts on canopy-scale fluxes contributing to water-use efficiency (WUE). These architectural traits are frequent targets for crop improvement and for improving the understanding and predictions of net ecosystem carbon and water fluxes. METHODS: A three-dimensional, leaf-resolving model along with a range of virtually generated hypothetical canopies were used to quantify interactions between canopy structure and WUE by examining its response to variation of leaf inclination independent of leaf azimuth, canopy heterogeneity, vegetation density and physiological parameters. KEY RESULTS: Overall, increasing leaf area index (LAI), increasing the daily-averaged fraction of leaf area projected in the sun direction (Gavg) via the leaf inclination or azimuth distribution and increasing homogeneity had a similar effect on canopy-scale daily fluxes contributing to WUE. Increasing any of these parameters tended to increase daily light interception, increase daily net photosynthesis at low LAI and decrease it at high LAI, increase daily transpiration and decrease WUE. Isolated spherical crowns could decrease photosynthesis by ~60 % but increase daily WUE ≤130 % relative to a homogeneous canopy with equivalent leaf area density. There was no observed optimum in daily canopy WUE as LAI, leaf angle distribution or heterogeneity was varied. However, when the canopy was dense, a more vertical leaf angle distribution could increase both photosynthesis and WUE simultaneously. CONCLUSIONS: Variation in leaf angle and density distributions can have a substantial impact on canopy-level carbon and water fluxes, with potential trade-offs between the two. These traits might therefore be viable target traits for increasing or maintaining crop productivity while using less water, and for improvement of simplified models. Increasing canopy density or decreasing canopy heterogeneity increases the impact of leaf angle on WUE and its dependent processes.

Appointment Pathways: Yield Management via Cause-and-Effect Modeling in the Outpatient Setting at Mayo Clinic.

Patients have multiple outpatient appointments for various reasons. Analyzing patients' related appointments provides insight into referral patterns, leading to recommendations for ideal care and more efficient planning. We model these appointments with causal graphs via Judea Pearl's causal graph approach. Once we define the causal relationships in the appointment data, we leverage a graph database and visualization software to investigate valuable patterns and relationships in patient care over time. The Pathways tool allows yield management at specialty, provider, or appointment levels. Leaders use this tool to anticipate a patient's downstream appointments; the tool provides insights into staffing and the impact of growing demand.

Kinetic factors of physiology and the dynamic light environment influence the economic landscape of short-term hydraulic risk.

Optimality-based models of stomatal conductance unify biophysical and evolutionary constraints and can improve predictions of land-atmosphere carbon and water exchange. Recent models incorporate hydraulic constraints by penalizing excessive stomatal opening in relation to hydraulic damage caused by low water potentials. We used simulation models to test whether penalties based solely on vulnerability curves adequately represent the optimality hypothesis, given that they exclude the effects of kinetic factors on stomatal behavior and integrated carbon balance. To quantify the effects of nonsteady-state phenomena on the landscape of short-term hydraulic risk, we simulated diurnal dynamics of leaf physiology for 10 000 patches of leaf in a canopy and used a ray-tracing model, Helios, to simulate realistic variation in sunfleck dynamics. Our simulations demonstrated that kinetic parameters of leaf physiology and sunfleck properties influence the economic landscape of short-term hydraulic risk, as characterized by the effect of stomatal strategy (gauged by the water potential causing a 50% hydraulic penalty) on both aggregated carbon gain and the aggregated carbon cost of short-term hydraulic risk. Hydraulic penalties in optimization models should be generalized to allow their parameters to account for kinetic factors, in addition to parameters of hydraulic vulnerability.

Catching Spores: Linking Epidemiology, Pathogen Biology, and Physics to Ground-Based Airborne Inoculum Monitoring.

Monitoring airborne inoculum is gaining interest as a potential means of giving growers an earlier warning of disease risk in a management unit or region. This information is sought by growers to aid in adapting to changes in the management tools at their disposal and the market-driven need to reduce the use of fungicides and cost of production. To effectively use inoculum monitoring as a decision aid, there is an increasing need to understand the physics of particle transport in managed and natural plant canopies to effectively deploy and use near-ground aerial inoculum data. This understanding, combined with the nuances of pathogen-specific biology and disease epidemiology, can serve as a guide to designing improved monitoring approaches. The complexity of any pathosystem and local environment are such that there is not a generalized approach to near-ground air sampler placement, but there is a conceptual framework to arrive at a "semi-optimal" solution based on available resources. This review is intended as a brief synopsis of the linkages among pathogen biology, disease epidemiology, and the physics of the aerial dispersion of pathogen inoculum and what to consider when deciding where to locate ground-based air samplers. We leverage prior work in developing airborne monitoring tools for hops, grapes, spinach, and turf, and research into the fluid mechanics governing particle transport in sparse canopies and urban and forest environments. We present simulation studies to demonstrate how particles move in the complex environments of agricultural fields and to illustrate the limited sampling area of common air samplers.

Platypnea-Orthodeoxia Syndrome in the Setting of Patent Foramen Ovale Without Pulmonary Hypertension or Major Lung Disease.

Background Patent foramen ovale (PFO)-associated platypnea-orthodeoxia syndrome is characterized by dyspnea and hypoxemia when upright. The pathogenesis is thought to involve an increase in right atrial pressure or change in degree of right to left shunting with upright posture. Methods and Results We sought to characterize patients with platypnea-orthodeoxia syndrome related to PFO without pulmonary hypertension. We retrospectively reviewed databases at 3 tertiary referral hospitals in New South Wales, Australia from 2000 to 2019. Fourteen patients with a mean age of 69±14 years had a PFO with wide tunnel separation. Mean New York Heart Association Classification was II (±0.9) and 7 inpatients had been confined to bed (from postural symptoms). Baseline oxygen saturations supine were 93%±5% and 84%±6% upright. Two patients had a minor congenital heart defect and 4 had mild parenchymal lung disease with preserved lung function. The mean aortic root diameter was 37±6 mm and distance between aortic root and posterior atrial wall was 16±2 mm. Platypnea-orthodeoxia syndrome was preceded by surgery in 5 patients and 1 patient had mild pneumonia. Successful closure of the PFO using an Amplatzer device was performed in 11 of 14 patients. Post-closure, all patients had New York Heart Association Classification I (improvement 1.6±0.9, P<0.003) and semi-recumbent oxygen saturations increased by 13%±8% (P<0.001, n=10). Conclusions Platypnea-orthodeoxia syndrome is a debilitating condition, curable by PFO closure. Anatomical distortion of the atrial septum related to a dilated aortic root or shortening of the distance between the aortic root and posterior atrial wall may contribute to the syndrome.

Single-Step Integration of Poly(3-Octylthiophene) and Single-Walled Carbon Nanotubes for Highly Reproducible Paper-Based Ion-Selective Electrodes.

Calibration of ion-selective electrodes (ISEs) is cumbersome, time-consuming, and constitutes a significant limitation for the development of single-use and wearable disposable sensors. To address this problem, we have studied the effect of ion-selective membrane solvent on ISE reproducibility by comparing tetrahydrofuran (THF) (a typical solvent for membrane preparation) and cyclohexanone. In addition, a single-step integration of semiconducting/transducer polymer poly(3-octylthiophene) (POT) with single-walled carbon nanotubes (SWCNTs) into the paper-based ISEs (PBISEs) substrate was introduced. PBISEs for potassium and sodium ions were developed, and these ISEs present outstanding sensor performance and high potential reproducibility, as low as ±1.0 mV (n = 3).

Helios: A Scalable 3D Plant and Environmental Biophysical Modeling Framework.

This article presents an overview of Helios, a new three-dimensional (3D) plant and environmental modeling framework. Helios is a model coupling framework designed to provide maximum flexibility in integrating and running arbitrary 3D environmental system models. Users interact with Helios through a well-documented open-source C++ API. Version 1.0 comes with model plug-ins for radiation transport, the surface energy balance, stomatal conductance, photosynthesis, solar position, and procedural tree generation. Additional plug-ins are also available for visualizing model geometry and data and for processing and integrating LiDAR scanning data. Many of the plug-ins perform calculations on the graphics processing unit, which allows for efficient simulation of very large domains with high detail. An example modeling study is presented in which leaf-level heterogeneity in water usage and photosynthesis of an orchard is examined to understand how this leaf-scale variability contributes to whole-tree and -canopy fluxes.

Radiation exposure during cardiac catheterisation is similar for both femoral and radial approaches.

OBJECTIVES: Radial approach invasive coronary angiography has been shown to be superior to the femoral approach in terms of reducing vascular access complications and improving patient comfort. However, one major limitation has been the perception of higher patient radiation exposure, with guidelines recommending 7mSv as an appropriate average effective dose (E) for routine coronary angiography. Therefore, we sought here to assess differences in radiation exposure between the femoral and radial access routes in patients undergoing diagnostic coronary angiography with or without angioplasty (CA +/- PCI), as performed by two operators, experienced in both techniques. METHODS: Consecutive patients (n=870) from July 2011-December 2012, undergoing routine CA +/- PCI at Royal Prince Alfred Hospital, Sydney by two experienced interventional cardiologists were identified. Radiation doses were automatically recorded as dose area products (DAPs) at procedure time and converted into E using a conversion factor of 0.18 mSv/(Gycm2), as validated by the National Radiological Protection Board (NRPB). RESULTS: Of the 870 patients, 598 underwent diagnostic CA (347 femoral, 251 radial); and 272 underwent CA+ PCI (179 femoral, 93 radial). The mean age of the patients was 65±12 years and the majority (n=617, 71%) were male. Both groups were well matched with respect to baseline demographics, clinical presentation and angiographic characteristics, though there was an excess of patients with a history of coronary grafts in the femoral group, due to operator preference. In the patients who underwent diagnostic CA, there was no significant difference in the average effective radiation dose for femoral versus radial arterial access (E=7.9±8.2 vs. 8.3±10.6mSv; p=0.66). Similarly, there was also no difference in average effective radiation dose for femoral versus radial arterial access in patients undergoing CA+PCI (E=13.2±8.1 vs E=14.4±8.3 mSv; p=0.26). CONCLUSION: In our high volume cardiac catheterisation laboratory, radiation doses for routine angiography were near UNSC targets. Patient radiation exposure was comparable between femoral and radial approaches, for both CA and CA +/- PCI. Thus, our results allay concerns that radial cardiac catheterisation might be associated with greater radiation exposure.

The accuracy of the compressible Reynolds equation for predicting the local pressure in gas-lubricated textured parallel slider bearings.

The validity of the compressible Reynolds equation to predict the local pressure in a gas-lubricated, textured parallel slider bearing is investigated. The local bearing pressure is numerically simulated using the Reynolds equation and the Navier-Stokes equations for different texture geometries and operating conditions. The respective results are compared and the simplifying assumptions inherent in the application of the Reynolds equation are quantitatively evaluated. The deviation between the local bearing pressure obtained with the Reynolds equation and the Navier-Stokes equations increases with increasing texture aspect ratio, because a significant cross-film pressure gradient and a large velocity gradient in the sliding direction develop in the lubricant film. Inertia is found to be negligible throughout this study.

Improving a patient appointment call center at Mayo Clinic.

PURPOSE: Contact centers for patient and referring physician are important to large medical-centers such as the Mayo Clinic's Central Appointment Office (CAO). The aim of this case study is to report the process and results of a major process improvement effort, designed to simultaneously improve service quality and efficiency. DESIGN/METHODOLOGY/APPROACH: Discrete-event simulation and optimization are used and linked to significant service improvements. FINDINGS: The process improvement efforts led to about a 70 percent improvement in patient service performance as measured by average answering-speed (ASA) and average abandonment rate (AAR). This was achieved without adding additional staff, despite call volume increasing by 12 percent. Evaluating process improvement projects is difficult owing to the "phased" implementation of changes. Thus, there is no true control against which to compare. Additionally, the results are based on a single case study. RESEARCH LIMITATIONS/IMPLICATIONS: Evaluation of process improvement projects is difficult due to the "phased" implementation of changes. Thus, there is no true control to compare against. PRACTICAL IMPLICATIONS: Contact center data and operations research methods, such as discrete-event simulation and optimization, can be integrated with change management, which results in significant process improvements in medical call-centers. ORIGINALITY/VALUE: Structured quantitative modeling of contact centers can be an important extension to traditional quality and process improvement techniques.

Abnormal pulmonary artery stiffness in pulmonary arterial hypertension: in vivo study with intravascular ultrasound.

BACKGROUND: There is increasing recognition that pulmonary artery stiffness is an important determinant of right ventricular (RV) afterload in pulmonary arterial hypertension (PAH). We used intravascular ultrasound (IVUS) to evaluate the mechanical properties of the elastic pulmonary arteries (PA) in subjects with PAH, and assessed the effects of PAH-specific therapy on indices of arterial stiffness. METHOD: Using IVUS and simultaneous right heart catheterisation, 20 pulmonary segments in 8 PAH subjects and 12 pulmonary segments in 8 controls were studied to determine their compliance, distensibility, elastic modulus and stiffness index ß. PAH subjects underwent repeat IVUS examinations after 6-months of bosentan therapy. RESULTS: AT BASELINE, PAH SUBJECTS DEMONSTRATED GREATER STIFFNESS IN ALL MEASURED INDICES COMPARED TO CONTROLS: compliance (1.50±0.11×10(-2) mm(2/)mmHg vs 4.49±0.43×10(-2) mm(2/)mmHg, p<0.0001), distensibility (0.32±0.03%/mmHg vs 1.18±0.13%/mmHg, p<0.0001), elastic modulus (720±64 mmHg vs 198±19 mmHg, p<0.0001), and stiffness index ß (15.0±1.4 vs 11.0±0.7, p = 0.046). Strong inverse exponential associations existed between mean pulmonary artery pressure and compliance (r(2) = 0.82, p<0.0001), and also between mean PAP and distensibility (r(2) = 0.79, p = 0.002). Bosentan therapy, for 6-months, was not associated with any significant changes in all indices of PA stiffness. CONCLUSION: Increased stiffness occurs in the proximal elastic PA in patients with PAH and contributes to the pathogenesis RV failure. Bosentan therapy may not be effective at improving PA stiffness.

An inter-laboratory comparison of urinary 3-hydroxypropylmercapturic acid measurement demonstrates good reproducibility between laboratories.

BACKGROUND: Biomarkers have been used extensively in clinical studies to assess toxicant exposure in smokers and non-smokers and have recently been used in the evaluation of novel tobacco products. The urinary metabolite 3-HPMA, a metabolite of the major tobacco smoke toxicity contributor acrolein, is one example of a biomarker used to measure exposure to tobacco smoke. A number of laboratories have developed liquid chromatography with tandem mass spectrometry (LC-MS/MS) based methods to measure urinary 3-HPMA; however, it is unclear to what extent the data obtained by these different laboratories are comparable. FINDINGS: This report describes an inter-laboratory comparison carried out to evaluate the comparability of 3-HPMA measurement between four laboratories. A common set of spiked and authentic smoker and non-smoker urine samples were used. Each laboratory used their in-house LC-MS/MS method and a common internal standard. A comparison of the repeatability ('r'), reproducibility ('R'), and coefficient of variation for 3-HPMA demonstrated that within-laboratory variation was consistently lower than between-laboratory variation. The average inter-laboratory coefficient of variation was 7% for fortified urine samples and 16.2% for authentic urine samples. Together, this represents an inter-laboratory variation of 12.2%. CONCLUSION: The results from this first inter-laboratory comparison for the measurement of 3-HPMA in urine demonstrate a reasonably good consensus between laboratories. However, some consistent measurement biases were still observed between laboratories, suggesting that additional work may be required to further reduce the inter-laboratory coefficient of variation.

The relationship between pulmonary artery and pulmonary capillary wedge pressure for the diagnosis of pulmonary vascular disease.

BACKGROUND: Left heart disease and pulmonary vascular disease (PVD) both lead to raised pulmonary artery pressure (PAP) but differ in pathophysiology, prognosis and treatment. There are currently no criteria for diagnosing PVD in the presence of left heart disease. We therefore studied the relationship between PAP and pulmonary capillary wedge pressure (PCWP, a measure of left atrial pressure) to help define when PAP should be considered 'out-of-proportion' to PCWP, thus suggestive of PVD. METHODS: Retrospective analysis of 898 consecutive simultaneous left and right heart catheterisations. Of these, 684 patients (age 63+/-14 years) were classified according to presence of absence of left heart disease. Multilinear regression explored the relationship between mean PAP and PCWP, age, gender, systemic haemodynamics and left heart disease diagnosis. RESULTS: Increasing PCWP, age and heart rate and female gender were associated with higher PAP (p<0.0001, p=0.049, p<0.0001 and p=0.0015, respectively). Thus, in males: (mean PAP)=0.94+[1.15 x (mean PCWP)]+[0.03 x (age)]+[0.07 x (heart rate)] (for females add 1.38 mm Hg). This model accounted for 75% of variability in PAP, with PCWP alone accounting for 74%. CONCLUSIONS: A strong linear relationship exists between PAP and PCWP, which may help identify PAP 'out-of-proportion' to PCWP, facilitating the diagnosis of PVD in patients with pulmonary hypertension and left heart disease.