Entrepreneurial Place Leadershipexplores how locations with entrepreneurial meaning are created, maintained, exploited, and amplified to generate future value, considering how entrepreneurs lead in a ...complex entrepreneurial landscape.
Microbes in soils and other environments produce extracellular enzymes to depolymerize and hydrolyze organic macromolecules so that they can be assimilated for energy and nutrients. Measuring soil ...microbial enzyme activity is crucial in understanding soil ecosystem functional dynamics. The general concept of the fluorescence enzyme assay is that synthetic C-, N-, or P-rich substrates bound with a fluorescent dye are added to soil samples. When intact, the labeled substrates do not fluoresce. Enzyme activity is measured as the increase in fluorescence as the fluorescent dyes are cleaved from their substrates, which allows them to fluoresce. Enzyme measurements can be expressed in units of molarity or activity. To perform this assay, soil slurries are prepared by combining soil with a pH buffer. The pH buffer (typically a 50 mM sodium acetate or 50 mM Tris buffer), is chosen for the buffer's particular acid dissociation constant (pKa) to best match the soil sample pH. The soil slurries are inoculated with a nonlimiting amount of fluorescently labeled (i.e. C-, N-, or P-rich) substrate. Using soil slurries in the assay serves to minimize limitations on enzyme and substrate diffusion. Therefore, this assay controls for differences in substrate limitation, diffusion rates, and soil pH conditions; thus detecting potential enzyme activity rates as a function of the difference in enzyme concentrations (per sample). Fluorescence enzyme assays are typically more sensitive than spectrophotometric (i.e. colorimetric) assays, but can suffer from interference caused by impurities and the instability of many fluorescent compounds when exposed to light; so caution is required when handling fluorescent substrates. Likewise, this method only assesses potential enzyme activities under laboratory conditions when substrates are not limiting. Caution should be used when interpreting the data representing cross-site comparisons with differing temperatures or soil types, as in situ soil type and temperature can influence enzyme kinetics.
Application of system thinking to the development, implementation and evaluation of childhood obesity prevention efforts represents the cutting edge of community-based prevention. We report on an ...approach to developing a system oriented community perspective on the causes of obesity.
Group model building sessions were conducted in a rural Australian community to address increasing childhood obesity. Stakeholders (n = 12) built a community model that progressed from connection circles to causal loop diagrams using scripts from the system dynamics literature. Participants began this work in identifying change over time in causes and effects of childhood obesity within their community. The initial causal loop diagram was then reviewed and elaborated by 50 community leaders over a full day session.
The process created a causal loop diagram representing community perceptions of determinants and causes of obesity. The causal loop diagram can be broken down into four separate domains; social influences; fast food and junk food; participation in sport; and general physical activity.
This causal loop diagram can provide the basis for community led planning of a prevention response that engages with multiple levels of existing settings and systems.
Urban development of watersheds increases runoff and nitrogen loads by adding urban impervious surfaces and increasing the hydrologic connectivity of these surfaces to streams. Storm water control ...measures (SCMs) are designed to disrupt this connectivity by retaining water in biologically active depressions where nitrogen retention, transformation, and removal occur. This work applies a mechanistic, spatially distributed, hydroecological model (RHESSys) to a suburban watershed in Charlotte, NC, with 15% total imperviousness (TI) and 33% watershed area mitigated by SCMs. We developed emergent relationships between watershed‐scale predictors (TI and connectivity to SCMs) and water and nitrogen response variables (storm water runoff ratios and nitrogen load by species). Results showed that annual runoff ratios were insensitive to increases in connectivity to SCMs (varying by ~1% of rainfall) because SCMs did not substantially increase evaporation but that runoff ratios increased by an average 0.2% per 1% increase in TI due to decreases in transpiration in the watershed. Generally, nitrate loads increased with TI but decreased as more surfaces were mitigated by SCMs. However, these nitrate reductions corresponded to increased export of dissolved organic nitrogen and ammonium. Together, these results indicate that SCMs act as both removers and transformers of nitrogen at the watershed scale. SCMs showed a net assimilation of nitrogen in warm months and net release in cool months, which offset the timing of nitrogen export relative to inputs. This work highlights that using a hydroecological, process‐based model reveals both the emergent relationships between watershed condition and response and the processes controlling those relationships.
Key Points
Mitigation of impervious surfaces with storm water control measures only changes annual runoff ratios by ~1%
Nitrate loads increased with total imperviousness but decreased with impervious surface connectivity to SCMs
Storm water control measures remove, retain, and transform nitrogen at the watershed scale
As a consequence of the tight linkages among soils, plants and microbes inhabiting the rhizosphere, we hypothesized that soil nutrient and microbial stoichiometry would differ among plant species and ...be correlated within plant rhizospheres.
We assessed plant tissue carbon (C) : nitrogen (N) : phosphorus (P) ratios for eight species representing four different plant functional groups in a semiarid grassland during near-peak biomass. Using intact plant species-specific rhizospheres, we examined soil C : N : P, microbial biomass C : N, and soil enzyme C : N : P nutrient acquisition activities.
We found that few of the plant species' rhizospheres demonstrated distinct stoichiometric properties from other plant species and unvegetated soil. Plant tissue nutrient ratios and components of below-ground rhizosphere stoichiometry predominantly differed between the C4 plant species Buchloe dactyloides and the legume Astragalus laxmannii. The rhizospheres under the C4 grass B. dactyloides exhibited relatively higher microbial C and lower soil N, indicative of distinct soil organic matter (SOM) decomposition and nutrient mineralization activities.
Assessing the ecological stoichiometry among plant species' rhizospheres is a high-resolution tool useful for linking plant community composition to below-ground soil microbial and nutrient characteristics. By identifying how rhizospheres differ among plant species, we can better assess how plant–microbial interactions associated with ecosystem-level processes may be influenced by plant community shifts.
•We present an approach for estimating hydrological connectivity of impervious areas.•Soils, rainfall, and relative area of disconnecting pervious control impervious connectivity.•Temporally varying ...parameters controls connectivity across low permeability soils.•Spatial flow path variability controls connectivity across highly permeable soils.
Recent studies have reported that connected impervious areas – those impervious surfaces that contribute directly to runoff in a storm network or stream – are a better indicator of hydrologic response, stream alteration, and water quality than total impervious area. However, most methods for quantifying connected impervious areas require major assumptions regarding the definition of ‘connection’, potentially over-simplifying the role of variable climates, slope gradients, soils conditions, and heterogeneous flow paths on impervious surface connectivity. This study presents a new conceptual model and method for estimating hydrologically connected impervious areas (HCIA) that explicitly considers the effect of landscape and storm variability. The model separates impervious surfaces into two categories: directly or physically connected (Aphys) and variably connected (Avar) (impervious that drains to pervious). Of these categories, we investigated the sensitivity of Avar connectivity to varying soil conditions, slope gradients, rainfall properties, and hillslope geometry using PySWMM (a python interface for SWMM5). Simulations spanned a large parameter space with varying soil, slope, rainfall properties and geometries (i.e., relationships between the impervious and downslope pervious areas). PySWMM simulations were used to train and test a regression tree that predicts infiltration and connectivity of runoff from Avar surfaces, which provides excellent fidelity with PySWMM outcomes. To enable use of these methods in practice, we developed an ArcGIS tool that (1) delineates subcatchments; (2) extracts the impervious surface categories Aphys and Avar; (3) applies the regression tree algorithm to predict the fraction of incident rainfall that produces runoff across Avar; and (4) summarizes the resulting HCIA by subcatchment. Analysis of the regression feature importance shows that, in general, Avar connectivity is highly sensitive to the soil type, rainfall depth, area fraction, and antecedent soil moisture conditions of the downslope pervious area. We find that temporally varying parameters (e.g., rainfall and antecedent soil moisture) control Avar connectivity in areas with low permeability soils, while spatial flow path variability (e.g., relative quantity of disconnecting pervious area) controls Avar connectivity in areas with highly permeable soils. The methods developed in this study can be used to identify impervious surface connectivity more accurately in urban watersheds, representing an important step forward for incorporating spatial heterogeneity in stormwater modeling and planning.
BACKGROUND: There is growing evidence that community-based interventions can reduce childhood obesity in older children. OBJECTIVE: We aimed to determine the effectiveness of the Romp & Chomp ...intervention in reducing obesity and promoting healthy eating and active play in children aged 0-5 y. DESIGN: Romp & Chomp was a community-wide, multisetting, multistrategy intervention conducted in Australia from 2004 to 2008. The intervention occurred in a large regional city (Geelong) with a target group of 12,000 children and focused on community capacity building and environmental (political, sociocultural, and physical) changes to increase healthy eating and active play in early-childhood care and educational settings. The evaluation was repeat cross-sectional with a quasiexperimental design and comparison sample. Main outcome measures were body mass index (BMI), standardized BMI (zBMI; according to the Centers for Disease Control and Prevention 2000 reference charts), and prevalence of overweight/obesity and obesity-related behaviors in children aged 2 and 3.5 y. RESULTS: After the intervention there was a significantly lower mean weight, BMI, and zBMI in the 3.5-y-old subsample and a significantly lower prevalence of overweight/obesity in both the 2- and 3.5-y-old subsamples (by 2.5 and 3.4 percentage points, respectively) than in the comparison sample (a difference of 0.7 percentage points; P < 0.05) compared with baseline values. Intervention child-behavioral data showed a significantly lower intake of packaged snacks (by 0.23 serving), fruit juice (0.52 serving), and cordial (0.43 serving) than that in the comparison sample (all P < 0.05). CONCLUSION: A community-wide multisetting, multistrategy intervention in early-childhood settings can reduce childhood obesity and improve young children's diets. This trial was registered with the Australian Clinical Trials Registry at anzctr.org.au as ACTRN12607000374460.
Calls for the adoption of a systems approach to chronic disease prevention date back at least ten years because of the potential to empower communities to identify and address the complex causes of ...overnutrition, undernutrition and climate change. Australia, like many countries, has high levels of obesity and extreme climate events. The Reflexive Evidence and Systems interventions to Prevent Obesity and Non-communicable Disease (RESPOND) trial aims to prevent unhealthy weight gain in children in 10 intervention and two pilot communities in north-east Victoria, Australia using community-based participatory approaches informed by systems science. Intervention activities co-designed in 2019 were disrupted by COVID-19 and bushfires. This paper explores the impacts of these 'shocks' on the local prevention workforce to implement actions within communities.
A case study design involving one-hour online focus groups and an on-line survey (November 2021-February 2022). Purposive sampling was used to achieve diverse representation from RESPOND stakeholders including local council, health services, primary care partnerships and department of health. The focus group interview schedule and survey questions were based on Durlak and DuPre's implementation factors.
Twenty-nine participants from seven different communities participated in at least one of nine focus groups to discuss the impacts of COVID-19 and bushfires on localised implementation. Twenty-eight participants (97% of focus group sample) also completed the on-line survey. Implementation of RESPOND stalled or stopped in most communities due to bushfires and/or COVID-19. These shocks resulted in organisational priorities changing, loss of momentum for implementation, redeployment of human resources, culminating in fatigue and exhaustion. Participants reported adaptation of RESPOND, but implementation was slowed due to limited resources.
Further research is needed to advance risk management strategies and protect resources within health promotion. System shocks such as bushfires and COVID-19 are inevitable, and despite multiple adaptation opportunities, this intervention approach was not 'shock proof'.
Serum 25-Hydroxyvitamin D, Diabetes, and Ethnicity in the Third National Health and Nutrition Examination Survey
Robert Scragg , PHD 1 ,
MaryFran Sowers , PHD 2 and
Colin Bell , PHD 3
1 School of ...Population Health, University of Auckland, Auckland, New Zealand
2 Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, Michigan
3 School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
Address correspondence and reprint requests to Dr. Robert Scragg, School of Population Health, University of Auckland, Private
Bag, Auckland, New Zealand. E-mail: r.scragg{at}auckland.ac.nz
Abstract
OBJECTIVE —To determine the association between serum 25-hydroxyvitamin D (25OHD) and diabetes risk and whether it varies by ethnicity.
RESEARCH DESIGN AND METHODS —We performed an analysis of data from participants who attended the morning examination of the Third National Health and
Nutrition Examination Survey (1988–1994), a cross-sectional survey of a nationally representative sample of the U.S. population.
Serum levels of 25OHD, which reflect vitamin D status, were available from 6,228 people (2,766 non-Hispanic whites, 1,736
non-Hispanic blacks, and 1,726 Mexican Americans) aged ≥20 years with fasting and/or 2-h plasma glucose and serum insulin
measurements.
RESULTS —Adjusting for sex, age, BMI, leisure activity, and quarter of year, ethnicity-specific odds ratios (ORs) for diabetes (fasting
glucose ≥7.0 mmol/l) varied inversely across quartiles of 25OHD in a dose-dependent pattern (OR 0.25 95% CI 0.11–0.60 for
non-Hispanic whites and 0.17 0.08–0.37 for Mexican Americans) in the highest vitamin D quartile (25OHD ≥81.0 nmol/l) compared
with the lowest 25OHD (≤43.9 nmol/l). This inverse association was not observed in non-Hispanic blacks. Homeostasis model
assessment of insulin resistance (log e ) was inversely associated with serum 25OHD in Mexican Americans ( P = 0.0024) and non-Hispanic whites ( P = 0.058) but not non-Hispanic blacks ( P = 0.93), adjusting for confounders.
CONCLUSIONS —These results show an inverse association between vitamin D status and diabetes, possibly involving insulin resistance, in
non-Hispanic whites and Mexican Americans. The lack of an inverse association in non-Hispanic blacks may reflect decreased
sensitivity to vitamin D and/or related hormones such as the parathyroid hormone.
25OHD, 25-hydroxyvitamin D
HOMA, homeostasis model assessment
MEC, mobile examination center
NHANES III, Third National Health and Nutrition Examination Survey
Footnotes
A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances.
Accepted September 7, 2004.
Received June 27, 2004.
DIABETES CARE
Abstract
Objective
To describe changes over time in dietary risk factor prevalence and non-communicable disease in Pacific Island Countries (PICTs).
Methods
Secondary analysis of data from 21,433 ...adults aged 25–69, who participated in nationally representative World Health Organization STEPs surveys in 8 Pacific Island Countries and Territories between 2002 and 2019. Outcomes of interest were changes in consumption of fruit and vegetables, hypertension, overweight and obesity, and hypercholesterolaemia over time. Also, salt intake and sugar sweetened beverage consumption for those countries that measured these.
Results
Over time, the proportion of adults consuming less than five serves of fruit and vegetables per day decreased in five countries, notably Tonga. From the most recent surveys, average daily intake of sugary drinks was high in Kiribati (3.7 serves), Nauru (4.1) and Tokelau (4.0) and low in the Solomon Islands (0.4). Average daily salt intake was twice that recommended by WHO in Tokelau (10.1 g) and Wallis and Futuna (10.2 g). Prevalence of overweight/obesity did not change over time in most countries but increased in Fiji and Tokelau. Hypertension prevalence increased in 6 of 8 countries. The prevalence of hypercholesterolaemia decreased in the Cook Islands and Kiribati and increased in the Solomon Islands and Tokelau.
Conclusions
While some Pacific countries experienced reductions in diet related NCD risk factors over time, most did not. Most Pacific adults (88%) do not consume enough fruit and vegetables, 82% live with overweight or obesity, 33% live with hypertension and 40% live with hypercholesterolaemia. Population-wide approaches to promote fruit and vegetable consumption and reduce sugar, salt and fat intake need strengthening.
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