Biogeographical comparison of the emergent macrophyte, Sagittaria platyphylla in its native and introduced ranges

Understanding why some plant species become invasive is important to predict and prevent future weed threats and identify appropriate management strategies. Many hypotheses have been proposed to explain why plants become invasive, yet few studies have quantitatively compared plant and population parameters between native and introduced range populations to gain an objective perspective on the causes of plant invasion. The present study uses a biogeographical field survey to compare morphological and reproductive traits and abundance between the native range (USA) and two introduced ranges (Australia and South Africa) of Sagittaria platyphylla (Engelm.) J.G. Sm (Alismataceae), a highly invasive freshwater macrophyte. Introduced and native populations differed in sexual reproductive output with the number of achenes per fruiting head and individual achene weight found to be 40% and 50% greater in introduced populations respectively. However, no other morphological traits were found to be consistently different between the native and both introduced ranges, especially after taking into account differences in environmental conditions between the three ranges. Although populations in introduced regions were larger and occupied greater percentage cover, no differences in plant density were evident. Our results suggest that, apart from sexual reproduction, many of the trait patterns observed in S. platyphylla are influenced by environmental and habitat conditions within the native and invaded ranges. We conclude that the enemy release hypothesis best explains the results observed for sexual reproduction. In particular, we hypothesise that a release from natural enemies, specifically a pre-dispersal seed predator, may induce reproductive plasticity in S. platyphylla

International expert workshop on the analysis of the economic and public health impacts of air pollution: workshop summary.

Forty-nine experts from 18 industrial and developing countries met on 6 September 2001 in Garmisch-Partenkirchen, Germany, to discuss the economic and public health impacts of air pollution, particularly with respect to assessing the public health benefits from technologies and policies that reduce greenhouse gas (GHG) emissions. Such measures would provide immediate public health benefits, such as reduced premature mortality and chronic morbidity, through improved local air quality. These mitigation strategies also allow long-term goals--for example, reducing the buildup of GHG emissions--to be achieved alongside short-term aims, such as immediate improvements in air quality, and therefore benefits to public health. The workshop aimed to foster research partnerships by improving collaboration and communication among various agencies and researchers; providing a forum for presentations by sponsoring agencies and researchers regarding research efforts and agency activities; identifying key issues, knowledge gaps, methodological shortcomings, and research needs; and recommending activities and initiatives for research, collaboration, and communication. This workshop summary briefly describes presentations made by workshop participants and the conclusions of three separate working groups: economics, benefits transfer, and policy; indoor air quality issues and susceptible populations; and development and transfer of dose-response relationships and exposure models in developing countries. Several common themes emerged from the working group sessions and subsequent discussion. Key recommendations include the need for improved communication and extended collaboration, guidance and support for researchers, advances in methods, and resource support for data collection, assessment, and research

The Effect of Body Composition Methodology on Resulting Energy Availability Assessments

Energy availability (EA) is defined as the total daily energy available to an individual after accounting for that expended during exercise and standardized to fat-free mass (FFM). Generally, EA values less than 30 kcal/kg FFM/day are considered “low” and have been associated with deleterious effects on reproductive and hormonal health in females. However, it is unclear whether the method used to estimate FFM influences the resulting EA values to a degree that may affect interpretation and clinical decision-making. PURPOSE: To determine the effect of FFM values derived from various methods of body composition assessment on the resulting range and interpretation of EA values. METHODS: Four EA estimates were generated in 38 healthy females (mean ± SD age: 25.6 ± 6.2 years; height: 163.6 ± 7.4 cm; weight: 64.7 ± 13.8 kg) using different combinations within a reasonable range of lower and higher (25 and 35 kcal/kg bodyweight, respectively) energy intake values and lower and higher (3.5 and 7 kcal/kg bodyweight, respectively) exercise energy expenditure values. Resulting estimates were then standardized to FFM values from air displacement plethysmography (ADP), bioelectrical impedance spectroscopy (BIS), and bioelectrical impedance analysis (BIA) from both a research-grade (multi-frequency) and consumer-grade (dual-frequency) device. Resulting EA values were then compared to those using FFM from dual-energy x-ray absorptiometry (DXA). Each estimate was assigned to one of three EA “zones”: “low” (less than 30 kcal/kg FFM), “reduced” (30-44.9 kcal/kg FFM), or “adequate” (≥45 kcal/kg FFM). Individual EA estimates that were in different zones when compared between two devices were considered discordant. RESULTS: When compared to DXA-derived estimates, EA values were discordant in up to 13-16% of individuals depending on body composition method used. Discordant values were generally more common in the plots assuming higher (35 kcal/kg bodyweight) energy intake values and were most likely to be considered “adequate” using DXA-derived FFM versus “reduced” using alternate methods. CONCLUSION: EA estimates are generally robust to the method of body composition assessment used. However, divergent interpretations may occur in a small minority of individuals in which alternate methods may provide lower EA values than DXA

A Between-sex Comparison of the Validity of Body Fat Percentage Estimates From Four Bioelectrical Impedance Analyzers

Bioelectrical impedance analysis (BIA) devices administer electrical currents through surface electrodes in contact with the hands and/or feet. The measured reactance and resistance of various bodily tissues to these currents are then used to estimate body fat percentage (BFP) and other body composition values of interest based on algorithms derived from validation data. Owing to different patterns of fat distribution between sexes, it is unclear whether the configuration of electrodes (i.e., hand-to-hand, foot-to-foot, or hand-to-foot) may affect the validity of these devices in males versus females. PURPOSE: The purpose of this study was to determine the validity of BFP values across four BIA devices – one consumer-grade foot-to-foot device (RENPHO Smart Bathroom Scale), one consumer-grade hand-to-hand device (Omron HBF-306), one consumer-grade octapolar device (InBody H20N), and one research-grade octapolar device (Seca mBCA 515/514) – against a criterion four-compartment model (4C), and to compare these values between males and females. METHODS: Seventy-four healthy participants (35 males and 39 females) were included in this analysis. Participants abstained from all food, fluid, caffeine, and alcohol for at least 8 hours prior to each visit. Total error (TE) was calculated as the root mean square error between the estimate of each BIA device and that of the 4C model. Standard error of the estimate (SEE) was defined as the residual standard error value from ordinary least squares regression. Constant error (CE) was calculated as the average difference between the estimate of each BIA device and that of the 4C model. RESULTS: Participants had a mean ±SD age of 27.2 ±7.3 years, height of 168.1 ±8.9 cm, weight of 72.2 ±16.7 kg, and 4C BFP of 24.9 ±9.2%. In the entire sample, ranges for validity metrics of interest were as follows: TE: 3.2% (Seca) to 7.2% (RENPHO); SEE: 3.3% (Seca) to 5.7% (RENPHO); CE: -0.02 ±3.4% (InBody) to -3.46 ±4.1% (Omron). Across all devices, both TE and SEE were lower in females, with the largest between-sex differences observed for the InBody and RENPHO. Both octapolar devices (InBody and Seca) exhibited low group-level error in males and females (all CE within ±0.32%). Meanwhile, the RENPHO and Omron devices generally underestimated BFP with a greater degree of underestimation in females (CE of -2.6% and -3.7%, respectively) than males (CE of -0.1% and -3.2%, respectively), particularly for the RENPHO. CONCLUSION: Among the four BIA devices investigated, octapolar devices tended to have higher validity overall. All devices demonstrated lower TE and SEE in females, with the greatest between-sex differences observed in the InBody and RENPHO models. Users should be aware that commercially available hand-to-hand or foot-to-foot BIA devices such as the Omron and RENPHO models used in this study may systematically underestimate BFP compared to a criterion 4C model. In contrast, hand-to-foot octapolar analyzers exhibit strong group-level validity in both sexes

Introducing willingness-to-pay for noise changes into transport appraisal: an application of benefit transfer.

Numerous research studies have elicited willingness-to-pay values for transport-related noise, however, in many industrialised countries including the UK, noise costs and benefits are still not incorporated into appraisals for most transport projects and policy changes (Odgaard et al, 2005; Grant-Muller et al, 2001). This paper describes the actions recently taken in the UK to address this issue, comprising: primary research based on the city of Birmingham; an international review of willingness-to-pay evidence; development of values using benefit transfers over time and locations; and integration with appraisal methods. Amongst the main findings are: that the willingness-to-pay estimates derived for the UK are broadly comparable with those used in appraisal elsewhere in Europe; that there is a case for a lower threshold at 1 45dB(A)Leq,18hr1 rather than the more conventional 55dB(A); and that values per dB(A) increase with the noise level above this threshold. There are significant issues over the valuation of rail versus road noise, the neglect of non-residential noise and the valuation of high noise levels in different countries. Conclusions are drawn regarding the feasibility of noise valuation based on benefit transfers in the UK and elsewhere, and future research needs in this field are discussed

Comparison of Laboratory-Grade and Consumer-Grade Hand-to-Foot Bioelectrical Impedance Analyzers for Body Composition Estimation

Bioelectrical impedance analysis (BIA) is a simple and effective technique to estimate body composition, including body fat percentage (BFP). While these analyzers are a popular method of describing a person’s body composition, laboratory-grade devices are expensive and inaccessible to most people. As a result, they may be an unrealistic method for consumers to use. However, consumer-grade devices are increasingly available. PURPOSE: The purpose of this study was to compare laboratory-grade and consumer-grade bioelectrical impedance analyzers. METHODS: Seventy-five adults (40 F, 35 M) were evaluated using a laboratory-grade, hand-to-foot, multifrequency bioelectrical impedance analyzer (BIALAB; Seca mBCA 515) and a consumer-grade, hand-to-foot, single frequency bioelectrical impedance analyzer (BIACON; Omron HBF-516). Both devices administer undetectable electrical pulses through one extremity that are measured at another extremity, where the voltage drop (impedance) is determined. This information is used to estimate body fluids and composition. RESULTS: A strong, statistically significant correlation between devices was observed for BFP (r: 0.93, R2: 0.87, pCON overestimated BFP by 3.5 ± 3.4% (mean ± SD) relative to BIALAB (BIACON: 28.3 ± 9.6%; BIALAB: 24.8 ± 9.3%; pCONCLUSION: These results collectively suggest that while the laboratory-grade and consumer-grade analyzers in our study exhibit strong correlations when assessing a group of individuals, the consumer-grade device overestimates BFP. Additionally, the SEE indicates that 3.4% error can be expected with the consumer-grade device. Overall, the Omron HBF-516 consumer-grade device may be an adequate and affordable option to estimate body composition in some contexts, but results should be interpreted cautiously when used in individuals

Validity of Hand-to-Foot and Foot-to-Foot Consumer Bioimpedance Analyzers: A Four-Compartment Model Comparison

Body fat percentage (BF%) is a useful variable for predicting disease risk and determining overall fitness. Consumer-grade bioimpedance analyzers seek to provide accurate body composition data while remaining affordable and accessible. PURPOSE: The purpose of this study was to compare body fat percentages obtained from hand-to-foot and foot-to-foot consumer bioimpedance analyzers to a gold standard 4-compartment (4C) model. METHODS: Seventy-five adults (40 F, 35 M; age: 27.2 ± 7.3 y; height: 168.1 ± 8.8 cm; BM: 72.1 ± 16.6 kg; 4C model BF%: 25.0 ± 9.2%) were evaluated by a 4C model, a consumer-grade hand-to-foot bioimpedance analyzer (BIA-HF; Tanita BC568) and two consumer-grade foot-to-foot bioimpedance analyzers (BIA-FF; Tanita BC554 and Tanita UM081). The 4C model comprised dual-energy X-ray absorptiometry, air displacement plethysmography, and bioimpedance spectroscopy. BF% estimates obtained by each bioimpedance analyzer were compared to the criterion 4C using the coefficient of determination (R2), standard error of the estimate (SEE), and Bland-Altman analysis. RESULTS: BIA-HF underestimated BF% by 1.4 ± 4.1%, and both BIA-FF overestimated BF% by 0.5 to 0.6 ± 5.7%. The R2 value was higher for BIA-HF as compared to both BIA-FF analyzers (0.81 vs. 0.64). The SEE and 95% limits of agreement (LOA) were lower for BIA-HF (SEE: 4.0%; LOA: 8.1%) as compared to both BIA-FF (SEE: 5.6%; LOA: 11.2%). No method demonstrated proportional bias based on Bland-Altman analysis. CONCLUSION: While both hand-to-foot and foot-to-foot consumer-grade bioimpedance analyzers demonstrated potentially meaningful errors when compared to a gold standard method, the hand-to-foot device exhibited better overall performance. Specifically, a stronger linear agreement with the 4C model and lower individual-level errors were observed with the hand-to-foot model as compared to both foot-to-foot models from the same manufacturer. The superior performance of the hand-to-foot analyzer could be due to its direct testing of both the upper and lower body, which is more similar to the methods used in the 4C model and a better representation of an individual’s overall body composition