Development of a new quantum trajectory molecular dynamics framework.

An extension to the wave packet description of quantum plasmas is presented, where the wave packet can be elongated in arbitrary directions. A generalized Ewald summation is constructed for the wave packet models accounting for long-range Coulomb interactions and fermionic effects are approximated by purpose-built Pauli potentials, self-consistent with the wave packets used. We demonstrate its numerical implementation with good parallel support and close to linear scaling in particle number, used for comparisons with the more common wave packet employing isotropic states. Ground state and thermal properties are compared between the models with differences occurring primarily in the electronic subsystem. Especially, the electrical conductivity of dense hydrogen is investigated where a 15% increase in DC conductivity can be seen in our wave packet model compared with other models. This article is part of the theme issue 'Dynamic and transient processes in warm dense matter'.

Phthalates, adipates, BPA, and pesticides in school meals.

BACKGROUND: Exposure to phthalates, adipates, bisphenol-A (BPA), and pesticides may have important health consequences for children, but little is known regarding their presence in school meals, a major food source for children. The aims of this study were to determine the presence of phthalates, adipates, BPA, and pesticides in school meals. METHODS: Using a cross-sectional design, n = 50 school meal components were collected from four school districts in New England (n = 8 elementary/K-8 schools) differing preparation methods (on-site scratch cooking and pre-packaged heat and serve meals with plastic films) between 2019 and 2021. Meal components were tested for the presence of phthalates, adipates, BPA, and pesticides by an independent laboratory. RESULTS: One adipate, DEHA, was detected in 42% of samples (range 0.08 mg/kg - 50.39 mg/kg). Among the prepackaged foods, DEHA was detected in 86% of samples, which also contained the highest average concentrations among all the samples tested. The phthalate Diisononyl phthalate (DINP) was detected in only one sample, and BPA was not detected in any of the samples tested. Pesticides were detected in 64% of produce and 27% of entrées, but most had levels that were lower than the average levels detected by the USDA's Pesticide Data Program and only one sample had levels that exceeded those detected by the USDA (Cyfluthrin levels in one sample of apples were 0.038 mg/kg compared with an USDA average range of 0.004-0.032 mg/kg). CONCLUSIONS: Overall pesticides and phthalate levels in school meals are low and BPA was not detected. However, this study suggests that manufacturers may be changing to less studied plasticizers such as DEHA. More studies should examine the impact of DEHA on human health, particularly among children. As schools transition back from the COVID-19 pandemic, foods packaged in plastic should be minimized where possible. Overall, school meals remain one of the healthiest options for children and policies that support on site cooking can further strengthen the quality of school meals.

Improving school lunch menus with multi-objective optimisation: nutrition, cost, consumption and environmental impacts.

OBJECTIVE: To support school foods programmes by evaluating the relationship between nutritional quality, cost, student consumption and the environmental impacts of menus. DESIGN: Using linear programming and data from previously served menu items, the relationships between the nutritional quality, cost, student consumption and the environmental impacts of lunch menus were investigated. Optimised lunch menus with the maximum potential student consumption and nutritional quality and lowest costs and environmental impacts were developed and compared with previously served menus (baseline). SETTING: Boston Public Schools (BPS), Boston Massachusetts, USA. PARTICIPANTS: Menu items served on the 2018-2019 BPS lunch menu (n 142). RESULTS: Using single-objective models, trade-offs were observed between most interests, but the use of multi-objective models minimised these trade-offs. Compared with the current weekly menus offered, multi-objective models increased potential caloric intake by up to 27 % and Healthy Eating Index scores by up to 19 % and reduced costs and environmental impacts by up to 13 % and 71 %, respectively. Improvements were made by reducing the frequency of beef and cheese entrées and increasing the frequency of fish and legume entrées on weekly menus. CONCLUSIONS: This work can be extrapolated to monthly menus to provide further direction for school districts, and the methods can be employed with different recipes and constraints. Future research should test the implementation of optimised menus in schools and consider the broader implications of implementation.

A stabilized linear finite element method for anisotropic poroelastodynamics with application to cardiac perfusion.

We propose a variational multiscale method stabilization of a linear finite element method for nonlinear poroelasticity. Our approach is suitable for the implicit time integration of poroelastic formulations in which the solid skeleton is anisotropic and incompressible. A detailed numerical methodology is presented for a monolithic formulation that includes both structural dynamics and Darcy flow. Our implementation of this methodology is verified using several hyperelastic and poroelastic benchmark cases, and excellent agreement is obtained with the literature. Grid convergence studies for both anisotropic hyperelastodynamics and poroelastodynamics demonstrate that the method is second-order accurate. The capabilities of our approach are demonstrated using a model of the left ventricle (LV) of the heart derived from human imaging data. Simulations using this model indicate that the anisotropicity of the myocardium has a substantial influence on the pore pressure. Furthermore, the temporal variations of the various components of the pore pressure (hydrostatic pressure and pressure resulting from changes in the volume of the pore fluid) are correlated with the variation of the added mass and dynamics of the LV, with maximum pore pressure being obtained at peak systole. The order of magnitude and the temporal variation of the pore pressure are in good agreement with the literature.

Postoperative neurologic symptoms in the operative arm after shoulder surgery with interscalene blockade: a systematic review.

OBJECTIVE: Postoperative neurologic symptoms (PONS) in the operative arm are important complications of shoulder surgery and interscalene blockade (ISB). This systematic review aimed to compare the risk of PONS between ISB and other techniques, and the relative safety of different agents used in ISB. METHODS: Our systematic review followed Cochrane review methodology and was registered in PROSPERO. A search of MEDLINE (Ovid), EMBASE (Ovid), and CENTRAL (Wiley) from inception to June 2020 was completed. We included randomized or quasi-randomized trials of patients (> five years old) undergoing shoulder surgery with any ISB technique as an intervention, compared with any other nonregional or regional technique, or ISB of alternate composition or technique. The primary outcome was PONS (study author defined) assessed a minimum of one week after surgery. RESULTS: Fifty-five studies totalling 6,236 participants (median, 69; range, 30-910) were included. Another 422 otherwise eligible trials were excluded because PONS was not reported. Heterogeneity in when PONS was assessed (from one week to one year) and the diagnostic criteria used precluded quantitative meta-analysis. The most common PONS definition, consisting of one or more of paresthesia, sensory deficit, or motor deficit, was only used in 16/55 (29%) trials. Risk of bias was low in 5/55 (9%) trials and high in 36/55 (65%) trials, further limiting any inferences. CONCLUSION: These findings highlight the need for a standardized PONS outcome definition and follow-up time, along with routine, rigorous measurement of PONS in trials of ISB. STUDY REGISTRATION: PROSPERO (CRD42020148496); registered 10 February 2020.

RéSUMé: OBJECTIF: Les symptômes neurologiques postopératoires (SNPO) dans le bras opéré sont une complication importante des chirurgies de l'épaule sous bloc interscalénique (BIS). Cette revue systématique visait à comparer le risque de SNPO entre le BIS et d'autres techniques, ainsi que l'innocuité relative de divers agents utilisés pour réaliser un BIS. MéTHODE: Notre revue systématique a suivi la méthodologie de révision Cochrane et a été enregistrée dans le registre PROSPERO. Une recherche a été menée dans les bases de données MEDLINE (Ovid), EMBASE (Ovid) et CENTRAL (Wiley) de leur création à juin 2020. Nous avons inclus les études randomisées ou quasi-randomisées de patients (> cinq ans) bénéficiant d'une chirurgie de l'épaule avec n'importe quelle technique de BIS en tant qu'intervention, comparée à toute autre technique régionale ou non régionale, ou à un BIS de composition ou de technique alternative. Le critère d'évaluation principal était les SNPO (définis par l'auteur de l'étude) évalué au moins une semaine après la chirurgie. RéSULTATS: Cinquante-cinq études totalisant 6236 participants (médiane, 69; intervalle, 30-910) ont été incluses. Quatre cent vingt-deux autres études autrement admissibles ont été exclues parce que les SNPO n'y étaient pas rapportés. L'hétérogénéité du moment auquel les SNPO ont été évalués (d'une semaine à un an) et les critères diagnostiques utilisés ont empêché la réalisation d'une méta-analyse quantitative. La définition la plus courante des SNPO, consistant en la présence de paresthésie, de déficit sensoriel et/ou de déficit moteur, n'a été utilisée que dans 16/55 (29 %) des études. Le risque de biais était faible dans 5/55 (9 %) des études et élevé dans 36/55 (65 %) des études, limitant davantage toute autre inférence. CONCLUSION: Ces résultats soulignent la nécessité d'une définition normalisée du critère de SNPO et du temps de suivi, ainsi que la nécessité d'une mesure systématique et rigoureuse des SNPO dans les études portant sur les blocs interscaléniques. ENREGISTREMENT DE L'éTUDE: PROSPERO (CRD42020148496); enregistrée le 10 février 2020.

Policy-Relevant Assessment of Urban CO2 Emissions.

Global fossil fuel carbon dioxide (FFCO2) emissions will be dictated to a great degree by the trajectory of emissions from urban areas. Conventional methods to quantify urban FFCO2 emissions typically rely on self-reported economic/energy activity data transformed into emissions via standard emission factors. However, uncertainties in these traditional methods pose a roadblock to implementation of effective mitigation strategies, independently monitor long-term trends, and assess policy outcomes. Here, we demonstrate the applicability of the integration of a dense network of greenhouse gas sensors with a science-driven building and street-scale FFCO2 emissions estimation through the atmospheric CO2 inversion process. Whole-city FFCO2 emissions agree within 3% annually. Current self-reported inventory emissions for the city of Indianapolis are 35% lower than our optimal estimate, with significant differences across activity sectors. Differences remain, however, regarding the spatial distribution of sectoral FFCO2 emissions, underconstrained despite the inclusion of coemitted species information.

Environmental and Economic Effects of Changing to Shelf-Stable Dairy or Soy Milk for the Breakfast in the Classroom Program.

OBJECTIVES: To estimate economic and environmental effects of reducing milk waste from the US Breakfast in the Classroom (BIC) School Breakfast Program by replacing conventional milk with shelf-stable dairy or soy milk. METHODS: We estimated net greenhouse gas emissions (GHGE; kg CO2 equivalents [e]) from replacing conventional milk with shelf-stable dairy or soy milk by adapting existing life cycle assessments and US Environmental Protection Agency Waste Reduction Model estimates to BIC parameters. We estimated net cost with school meal purchasing data. RESULTS: Replacing conventional dairy milk with shelf-stable dairy or soy milk would reduce milk-associated GHGE by 28.5% (0.133 kg CO2e) or 79.8% (0.372 kg CO2e) per student per meal, respectively. Nationally, this equates to driving 248 million or 693 million fewer miles annually, respectively. This change would increase milk costs 1.9% ($0.005) or 59.4% ($0.163) per student per meal, respectively. CONCLUSIONS: Replacing conventional milk with shelf-stable dairy or soy milk could substantially reduce waste and concomitant GHGE in BIC; switching to shelf-stable dairy has low net costs. Pilot tests of these options are warranted to optimize the nutritional value, cost, and sustainability of BIC.

Synthesis of Urban CO2 Emission Estimates from Multiple Methods from the Indianapolis Flux Project (INFLUX).

Urban areas contribute approximately three-quarters of fossil fuel derived CO2 emissions, and many cities have enacted emissions mitigation plans. Evaluation of the effectiveness of mitigation efforts will require measurement of both the emission rate and its change over space and time. The relative performance of different emission estimation methods is a critical requirement to support mitigation efforts. Here we compare results of CO2 emissions estimation methods including an inventory-based method and two different top-down atmospheric measurement approaches implemented for the Indianapolis, Indiana, U.S.A. urban area in winter. By accounting for differences in spatial and temporal coverage, as well as trace gas species measured, we find agreement among the wintertime whole-city fossil fuel CO2 emission rate estimates to within 7%. This finding represents a major improvement over previous comparisons of urban-scale emissions, making urban CO2 flux estimates from this study consistent with local and global emission mitigation strategy needs. The complementary application of multiple scientifically driven emissions quantification methods enables and establishes this high level of confidence and demonstrates the strength of the joint implementation of rigorous inventory and atmospheric emissions monitoring approaches.

Estimating the Vertical Structure of Weather-Induced Mission Costs for Small UAS.

The performance of small uninhabited aerial systems (UAS) is very sensitive to the atmospheric state. Improving awareness of the environment and its impact on mission performance is important to enabling greater autonomy for small UAS. A modeling system is proposed that allows a small UAS to build a model of the atmospheric state using computational resources available onboard the aircraft and relate the atmospheric state to the cost of completing a mission. In this case, mission cost refers to the energy required per distance traveled. The system can use in situ observations made by the aircraft, but can also incorporate observations from other aircraft and sensors. The modeling system is demonstrated in a flight test aboard a small UAS and validated against radiosondes and numerical weather model analyses. The test demonstrates that the modeling system can represent the atmospheric state and identifies times where significant error exists between the state expected by the numerical weather model and that observed. Transformation of the atmospheric state into a mission performance cost identifies cases where the mission performance cost predicted by a numerical weather model differs from that observed by more than 30%.

Direct and Indirect Measurements and Modeling of Methane Emissions in Indianapolis, Indiana.

This paper describes process-based estimation of CH4 emissions from sources in Indianapolis, IN and compares these with atmospheric inferences of whole city emissions. Emissions from the natural gas distribution system were estimated from measurements at metering and regulating stations and from pipeline leaks. Tracer methods and inverse plume modeling were used to estimate emissions from the major landfill and wastewater treatment plant. These direct source measurements informed the compilation of a methane emission inventory for the city equal to 29 Gg/yr (5% to 95% confidence limits, 15 to 54 Gg/yr). Emission estimates for the whole city based on an aircraft mass balance method and from inverse modeling of CH4 tower observations were 41 ± 12 Gg/yr and 81 ± 11 Gg/yr, respectively. Footprint modeling using 11 days of ethane/methane tower data indicated that landfills, wastewater treatment, wetlands, and other biological sources contribute 48% while natural gas usage and other fossil fuel sources contribute 52% of the city total. With the biogenic CH4 emissions omitted, the top-down estimates are 3.5-6.9 times the nonbiogenic city inventory. Mobile mapping of CH4 concentrations showed low level enhancement of CH4 throughout the city reflecting diffuse natural gas leakage and downstream usage as possible sources for the missing residual in the inventory.

Daily Saturated Fat and Sodium Content of Elementary School Meals in a Large Sample of 128 Geographically Diverse School Systems in the United States.

BACKGROUND: Despite federal regulations limiting saturated fat and sodium levels on a weekly average basis, daily nutrient content of school meals in the United States is not regulated, leading to potential large fluctuations and intake well in excess of dietary recommendations. OBJECTIVE: To assess the daily prevalence of potential public elementary school meal combinations that were high in saturated fat and sodium (using cutoffs based on the US Department of Agriculture weekly average reimbursable meal thresholds), and to identify saturated fat and sodium thresholds for entrées to limit full meals exceeding those cutoffs. DESIGN: Cross-sectional. PARTICIPANTS AND SETTING: Four weeks of publicly available public elementary school (kindergarten through grade five) breakfast and lunch menus with associated nutrition data were collected from a national stratified random sample of 128 school districts during fall 2019. MAIN OUTCOME MEASURES: Percent of meal combinations exceeding the saturated fat and Target 1 sodium thresholds were calculated, as well as thresholds for saturated fat and sodium levels in breakfast and lunch entrées. STATISTICAL ANALYSES: Descriptive statistics and logistic regression were used to examine the odds of alignment with sodium and saturated fat US Department of Agriculture thresholds. RESULTS: The prevalence of elementary breakfast and lunch meal combinations that were high in sodium was on average 11% and 12.4%, respectively, and for saturated fat was 10.6% and 34%, respectively. Entrées above certain thresholds (≥400 and ≥1,000 mg sodium and ≥4.5 and ≥6 g saturated fat for breakfast and lunch, respectively) had a higher odds of producing a reimbursable meal that was high in sodium and saturated fat. CONCLUSIONS: There is widespread availability of high-saturated fat and sodium elementary school meal combinations on a daily basis. Daily thresholds, in addition to weekly nutrient thresholds, as well as limits on sodium and saturated fat for entrées, may therefore be needed to prevent daily excess intake of saturated fat and sodium among elementary students.

Modelling the Progression of Competitive Performance of an Academy's Soccer Teams.

Progression of a team's performance is a key issue in competitive sport, but there appears to have been no published research on team progression for periods longer than a season. In this study we report the game-score progression of three teams of a youth talent-development academy over five seasons using a novel analytic approach based on generalised mixed modelling. The teams consisted of players born in 1991, 1992 and 1993; they played totals of 115, 107 and 122 games in Asia and Europe between 2005 and 2010 against teams differing in age by up to 3 years. Game scores predicted by the mixed model were assumed to have an over-dispersed Poisson distribution. The fixed effects in the model estimated an annual linear pro-gression for Aspire and for the other teams (grouped as a single opponent) with adjustment for home-ground advantage and for a linear effect of age difference between competing teams. A random effect allowed for different mean scores for Aspire and opposition teams. All effects were estimated as factors via log-transformation and presented as percent differences in scores. Inferences were based on the span of 90% confidence intervals in relation to thresholds for small factor effects of x/÷1.10 (+10%/-9%). Most effects were clear only when data for the three teams were combined. Older teams showed a small 27% increase in goals scored per year of age difference (90% confidence interval 13 to 42%). Aspire experienced a small home-ground advantage of 16% (-5 to 41%), whereas opposition teams experienced 31% (7 to 60%) on their own ground. After adjustment for these effects, the Aspire teams scored on average 1.5 goals per match, with little change in the five years of their existence, whereas their opponents' scores fell from 1.4 in their first year to 1.0 in their last. The difference in progression was trivial over one year (7%, -4 to 20%), small over two years (15%, -8 to 44%), but unclear over >2 years. In conclusion, the generalized mixed model has marginal utility for estimating progression of soccer scores, owing to the uncertainty arising from low game scores. The estimates are likely to be more precise and useful in sports with higher game scores. Key pointsA generalized linear mixed model is the approach for tracking game scores, key performance indicators or other measures of performance based on counts in sports where changes within and/or between games/seasons have to be considered.Game scores in soccer could be useful to track performance progression of teams, but hundreds of games are needed.Fewer games will be needed for tracking performance represented by counts with high scores, such as game scores in rugby or key performance indicators based on frequent events or player actions in any team sport.

Measurements of Atmospheric Methane Emissions from Stray Gas Migration: A Case Study from the Marcellus Shale.

Understanding emissions of methane from legacy and ongoing shale gas development requires both regional studies that assess the frequency of emissions and case studies that assess causation. We present the first direct measurements of emissions in a case study of a putatively leaking gas well in the largest shale gas play in the United States. We quantify atmospheric methane emissions in farmland >2 km from the nearest shale gas well cited for casing and cementing issues. We find that emissions are highly heterogeneous as they travel long distances in the subsurface. Emissions were measured near observed patches of dead vegetation and methane bubbling from a stream. An eddy covariance flux tower, chamber flux measurements, and a survey of enhancements of the near-surface methane mole fraction were used to quantify emissions and evaluate the spatial and temporal variability. We combined eddy covariance measurements with the survey of the methane mole fraction to estimate total emissions over the study area (2,800 m2). Estimated at ∼6 kg CH4 day-1, emissions were spatially heterogeneous but showed no temporal trends over 6 months. The isotopic signature of the atmospheric CH4 source (δ13CH4) was equal to -29‰, consistent with methane of thermogenic origin and similar to the isotopic signature of the gas reported from the nearest shale gas well. While the magnitude of emissions from the potential leak is modest compared to large emitters identified among shale gas production sites, it is large compared to estimates of emissions from single abandoned wells. Since other areas of emissions have been identified close to this putatively leaking well, our estimate of emissions likely represents only a portion of total emissions from this event. More comprehensive quantification will require more extensive spatial and temporal sampling of the locations of gas migration to the surface as well as an investigation into the mechanisms of subsurface gas migration. This work highlights an example of atmospheric methane emissions from potential stray gas migration at a location far from a well pad, and further research should explore the frequency and mechanisms behind these types of events to inform careful and strategic natural gas development.

Nutrient Content and Compliance with Sodium Standards in Elementary School Meals in the United States Pre- and Post-COVID-19.

Various federal policies have weakened school meal nutrition standards in the United States since the passage of the Healthy, Hunger-Free Kids Act in 2010, including temporary school meal nutrition waivers to promote post-COVID-19 pandemic recovery. This study used school menu and nutrient data from a nationally representative sample of 128 elementary school districts to examine differences in nutrients (average calories, total fat, saturated fat, sodium, total sugar, and fiber) and alignment with United States Department of Agriculture (USDA) sodium targets in 2019 (pre-pandemic) and in 2022 (post-pandemic). Data were analyzed using analysis of variance accounting for repeated measures within school districts, adjusting for geographic region and urbanicity. Small differences in the nutrient content for both breakfast and lunch were observed between 2019 and 2022. Most weeks met USDA sodium Target 1 for breakfast (≥95% of weeks) and Target 1 (≥96% of weeks) and Target 1A for lunch (≥92% of weeks) in both 2019 and 2022, although compliance decreased slightly when condiments were included. Additionally, meals provided on average 57 g of total sugar. Overall, many meals are already in alignment with lower sodium targets. Simple strategies, such as offering lower sodium condiments, can further reduce sodium in school meals. The total sugar levels observed highlight that the USDA should consider limits on added sugars in school meals.

A multi-city urban atmospheric greenhouse gas measurement data synthesis.

Urban regions emit a large fraction of anthropogenic emissions of greenhouse gases (GHG) such as carbon dioxide (CO2) and methane (CH4) that contribute to modern-day climate change. As such, a growing number of urban policymakers and stakeholders are adopting emission reduction targets and implementing policies to reach those targets. Over the past two decades research teams have established urban GHG monitoring networks to determine how much, where, and why a particular city emits GHGs, and to track changes in emissions over time. Coordination among these efforts has been limited, restricting the scope of analyses and insights. Here we present a harmonized data set synthesizing urban GHG observations from cities with monitoring networks across North America that will facilitate cross-city analyses and address scientific questions that are difficult to address in isolation.

Availability of Lower-Sodium School Lunches and the Association with Selection and Consumption among Elementary and Middle School Students.

BACKGROUND: During 2010, the US Department of Agriculture updated the school meals standards, including three progressively decreasing sodium targets. The Target 1 standards went into effect in 2014, but during 2018, the US Department of Agriculture delayed the Target 2 standards until 2024 and eliminated the Target 3 standards citing concerns regarding the availability and acceptability of lower-sodium foods. In addition, there are currently no sugar standards, and it is unknown whether sugar is substituted for salt in lower-sodium school foods. OBJECTIVE: To examine the availability, selection, and consumption of school lunches already in alignment with the Target 2 and 3 sodium levels and the association between sodium and sugar. DESIGN: An observational cafeteria-based study conducted during fall 2018. PARTICIPANTS AND SETTING: Students (n = 1985) in grades three through eight attending 13 elementary/kindergarten through eighth-grade schools in a large, urban school district in New England. MAIN OUTCOME MEASURES: Availability, selection, and consumption were examined using plate waste methodology. STATISTICAL ANALYSES PERFORMED: Mixed-model analysis of variance accounting for student demographic characteristics with schools/students as a random effect (students nested within schools) were used to examine differences in availability, selection, and consumption. Linear regression was used to examine the association between sodium and sugar in the school foods. RESULTS: The majority of meals selected (87%) and consumed (98%) were already in alignment with the Target 2 standards. There were significant inverse associations between sodium levels and consumption; each 100-mg increase in sodium was associated with a decrease in consumption by 2% for entrées (P = 0.002) and 5% for vegetables (P = 0.01). When examining the association between sodium and sugar, each 10-mg reduction in sodium was associated with 1-g increase in sugar among entrées (P < 0.0001), whereas there was a significant positive association between sodium and sugar with vegetables and condiments. CONCLUSIONS: This study provides some evidence that schools may already have the ability to provide lower-sodium meals that are acceptable to students, and therefore the recent rollbacks to the sodium standards may be unwarranted. Study findings suggest that the US Department of Agriculture should take under consideration policies that would limit added sugar for school meals as sugar may be substituted for salt.

A poroelastic immersed finite element framework for modelling cardiac perfusion and fluid-structure interaction.

Modern approaches to modelling cardiac perfusion now commonly describe the myocardium using the framework of poroelasticity. Cardiac tissue can be described as a saturated porous medium composed of the pore fluid (blood) and the skeleton (myocytes and collagen scaffold). In previous studies fluid-structure interaction in the heart has been treated in a variety of ways, but in most cases, the myocardium is assumed to be a hyperelastic fibre-reinforced material. Conversely, models that treat the myocardium as a poroelastic material typically neglect interactions between the myocardium and intracardiac blood flow. This work presents a poroelastic immersed finite element framework to model left ventricular dynamics in a three-phase poroelastic system composed of the pore blood fluid, the skeleton, and the chamber fluid. We benchmark our approach by examining a pair of prototypical poroelastic formations using a simple cubic geometry considered in the prior work by Chapelle et al (2010). This cubic model also enables us to compare the differences between system behaviour when using isotropic and anisotropic material models for the skeleton. With this framework, we also simulate the poroelastic dynamics of a three-dimensional left ventricle, in which the myocardium is described by the Holzapfel-Ogden law. Results obtained using the poroelastic model are compared to those of a corresponding hyperelastic model studied previously. We find that the poroelastic LV behaves differently from the hyperelastic LV model. For example, accounting for perfusion results in a smaller diastolic chamber volume, agreeing well with the well-known wall-stiffening effect under perfusion reported previously. Meanwhile differences in systolic function, such as fibre strain in the basal and middle ventricle, are found to be comparatively minor.

The influence of near-field fluxes on seasonal carbon dioxide enhancements: results from the Indianapolis Flux Experiment (INFLUX).

BACKGROUND: Networks of tower-based CO2 mole fraction sensors have been deployed by various groups in and around cities across the world to quantify anthropogenic CO2 emissions from metropolitan areas. A critical aspect in these approaches is the separation of atmospheric signatures from distant sources and sinks (i.e., the background) from local emissions and biogenic fluxes. We examined CO2 enhancements compared to forested and agricultural background towers in Indianapolis, Indiana, USA, as a function of season and compared them to modeled results, as a part of the Indianapolis Flux (INFLUX) project. RESULTS: At the INFLUX urban tower sites, daytime growing season enhancement on a monthly timescale was up to 4.3-6.5 ppm, 2.6 times as large as those in the dormant season, on average. The enhancement differed significantly depending on choice of background and time of year, being 2.8 ppm higher in June and 1.8 ppm lower in August using a forested background tower compared to an agricultural background tower. A prediction based on land cover and observed CO2 fluxes showed that differences in phenology and drawdown intensities drove measured differences in enhancements. Forward modelled CO2 enhancements using fossil fuel and biogenic fluxes indicated growing season model-data mismatch of 1.1 ± 1.7 ppm for the agricultural background and 2.1 ± 0.5 ppm for the forested background, corresponding to 25-29% of the modelled CO2 enhancements. The model-data total CO2 mismatch during the dormant season was low, - 0.1 ± 0.5 ppm. CONCLUSIONS: Because growing season biogenic fluxes at the background towers are large, the urban enhancements must be disentangled from the biogenic signal, and growing season increases in CO2 enhancement could be misinterpreted as increased anthropogenic fluxes if the background ecosystem CO2 drawdown is not considered. The magnitude and timing of enhancements depend on the land cover type and net fluxes surrounding each background tower, so a simple box model is not appropriate for interpretation of these data. Quantification of the seasonality and magnitude of the biological fluxes in the study region using high-resolution and detailed biogenic models is necessary for the interpretation of tower-based urban CO2 networks for cities with significant vegetation.

Impact of the Updated USDA School Meal Standards, Chef-Enhanced Meals, and the Removal of Flavored Milk on School Meal Selection and Consumption.

BACKGROUND: In Fall 2012, updated US Department of Agriculture school meal standards went into effect and did not result in increased food waste overall. However, consumption of school foods, especially fruits and vegetables, remains low. Therefore, strategies to improve school meal consumption are necessary. OBJECTIVE: This study evaluated the combined impact of the updated school meal standards and chef-enhanced, healthier meals, and the removal of flavored milk on students' school food selection and consumption compared with students in control schools. DESIGN: The Project MEALS (Modifying Eating and Lifestyles at School) study was a cafeteria-based quasi-experimental intervention conducted during the 2012 to 2013 school year. PARTICIPANTS/SETTING: Participants were students (n=1,309) in grades 3 through 8 attending four intervention and four control schools in two low-income, urban school districts. INTERVENTION: Chef-enhanced school meals and the removal of flavored milk combined with the updated US Department of Agriculture school meal standards. MAIN OUTCOME MEASURES: Changes in school meal selection and consumption were examined using plate waste methodology. STATISTICAL ANALYSES PERFORMED: Logistic regression and mixed-model analysis of variance adjusting for student demographics and schools/students as a random effect (students nested within schools) were used to examine differences in selection and consumption before (Fall 2012) and after (Spring 2013) a chef-based intervention with the updated school meal standards. RESULTS: After the chef-based intervention was implemented, there were no significant differences in entrée, vegetable, or fruit selection. Significantly fewer students selected milk compared with students in control schools (56.8% vs 94.0%; P<0.0001) and milk consumption was significantly lower (54.8% vs 63.7%; P=0.004). However, consumption was significantly greater for vegetables (62.2% vs 38.2%; P=0.005) and fruits (75.2 vs 59.2%; P=0.04) in the intervention schools compared with control schools. There were no significant differences in entrée consumption. CONCLUSIONS: Schools collaborating with chefs can be an effective method to improve the consumption of fruits and vegetables with the updated US Department of Agriculture school meal standards. Further research should examine the longer-term impact of the removal of flavored milk from schools to determine whether the lower selection and consumption rates persist.

Pilot Evaluation of Aggregate Plate Waste as a Measure of Students' School Lunch Consumption.

BACKGROUND: Weighing an individual's plate waste provides reliable estimates of food intake by physically weighing individual food components to the nearest gram before and after a meal. Weighing aggregate, school-level food waste may be an inexpensive and less time-consuming alternative. However, it has not been determined whether aggregate plate waste is an accurate measure of individually weighed plate waste. OBJECTIVE: This pilot study aimed to evaluate the accuracy of aggregate plate waste for quantifying food waste in a school cafeteria setting in comparison with individually weighed plate waste. DESIGN: A pilot validation study in which aggregate plate waste was compared against individually weighed plate waste in a school cafeteria setting. PARTICIPANTS/SETTING: This study took place in an urban, low-income school district in Massachusetts in the spring of 2014. Four elementary schools with identical cafeterias and meals participated in the study. Approximately 1,700 students participated in this study. MAIN OUTCOME MEASURES: For individually weighed plate waste, the percent discarded was calculated by dividing the weight of each discarded item by the average weight of the food item served and the percent consumed was calculated as the residual. For aggregate-level measurements, waste was separated by component (entrée, vegetable, fruit, and milk), and the weight discarded was calculated based on the weight of the cumulative amount remaining and an average weight for each food item served, with the percent consumed calculated as the residual. STATISTICAL ANALYSES PERFORMED: Intraclass correlation coefficients (ICCs) were calculated to assess the agreement between aggregate plate waste and individual-level plate waste values. RESULTS: Agreement was excellent for entrées (ICC=0.90) and vegetables (ICC=0.78), but poor for milk (ICC=0.22) and fruits (ICC=0.23). The overall agreement for all four components combined was excellent (ICC=0.75). CONCLUSIONS: Results suggest that aggregate plate waste may provide a reasonable estimate of individually weighed plate waste, but additional research is warranted.