Stepping over obstacles: Attention demands and aging

Older adults have been shown to trip on obstacles despite taking precautions to step carefully. It has been demonstrated in dual-task walking that age-related decline in cognitive and attentional mechanisms can compromise postural management. This is yet to be substantiated during obstacle negotiation when walking. Forty-six healthy volunteers (aged 20-79 years) stepped over obstacles in their path whilst walking and performing a verbal fluency task. Using 3D kinematic analysis we compared obstacle crossing during single (obstacle crossing only) and dual-task (obstacle crossing with verbal task) conditions. We grouped the participants into three age groups and examined age-related changes to cognitive interference on obstacle crossing. During dual-task trials, the 20-29 and 60-69 groups stepped closer to the obstacles prior to crossing, increased vertical toe-obstacle clearance, and had reduced gait variability. In these two groups there was a small dual-task decrease in verbal output. The 70-79 group applied similar dual-task stepping strategies during pre-crossing. However, during crossing they showed reduced vertical toe-to-obstacle clearance and increased variability of obstacle-to-heel distance. Additionally, this group did not show any significant change to verbal output across trials. These results suggest that with advanced age, increased cognitive demands are more likely to have a detrimental impact on motor performance, leading to compromised safety margins and increased variability in foot placement. We conclude that younger adults utilise a posture-preserving strategy during complex tasks but the likelihood of this strategy being used decreases with advanced age

Temporal dynamics of the shrub and herbaceous layer of an area of moist grassland in Alto Paraíso de Goiás, Brazil

Este trabalho avaliou a dinâmica estrutural e fl orística de uma comunidade de espécies herbáceo-arbustivas de uma área de campo limpo úmido em Alto Paraíso de Goiás, o primeiro inventário realizado em 2000 (T0) e o segundo em 2007 (T1). A diversidade de Shannon entre os períodos foi comparada pelo teste-t de Hutcheson e a similaridade fl orística, pelo índice de similaridade de Chao-Sørensen. As relações fl orísticas e a cobertura, entre os períodos e as linhas, foram avaliadas por meio de análises de correspondência retifi cada (DCA). Foram amostradas 98 espécies, 88 no T0 e 67 no T1, sendo 31 exclusivas do T0 e 10 do T1. A diversidade fl orística na comunidade foi elevada nos dois períodos, porém diferente entre esses (t = 7,12; p < 0,001), devido a variação no número e cobertura das espécies. A similaridade entre os dois inventários foi alta (Chao-Sørensen ± IC = 0,841 ± 0,074). A ordenação por DCA indicou relações entre a composição fl orística e a cobertura com o gradiente de umidade e de matéria orgânica no solo identifi cados em T0. Houve modifi cações nas linhas em zonas sazonais, as quais se tornaram mais semelhantes às linhas constantemente saturadas por água. Em um intervalo de sete anos o campo limpo úmido apresentou mudanças na composição fl orística e, principalmente na estrutura devido o aumento da cobertura de espécies perenes, cespitosas e entouceiradas, que foram favorecidas pela maior umidade no solo em resposta à elevação da pluviosidade da região. __________________________________________________________________________________________ ABSTRACTTh is study evaluated the fl oristic and structural dynamics of a community of herbaceous-shrub species in an area of moist grassland in Alto Paraíso de Goiás. Th e fi rst inventory was undertaken in 2000 (T0) and the second in 2007 (T1). Shannon’s diversity between the periods was compared by Hutchesons´s t-test, and the fl oristic similarity by the Chao-Sørensen similarity index. Floristic composition and cover, between periods and lines, were evaluated by detrended correspondence analysis (DCA). We sampled 98 species, 88 at T0 and 67 at T1; 31 were unique to T0 and 10 to T1. Floristic diversity in the community was high in both periods, but diff erent between them (t = 7.12, p <0.001), due to variation in species number and coverage. Similarity between the two surveys was high (Chao-Sørensen CI = ± 0.841 ± 0.074). Th e DCA ordination indicated relationships between the fl oristic composition and cover with a gradient of moisture and organic matter in the soil identifi ed in T0. Th ere were changes in the lines in the seasonal zones, which became more similar in those constantly saturated with water. During an interval of seven years the moist grassland showed changes in fl oristic composition and mainly in structure due to increased cover of the clumped tussock perennial species, which were favored by higher soil moisture due to high rainfall in the region

Associations between Prenatal Urinary Biomarkers of Phthalate Exposure and Preterm Birth: A Pooled Study of 16 US Cohorts

Importance: Phthalate exposure is widespread among pregnant women and may be a risk factor for preterm birth. Objective: To investigate the prospective association between urinary biomarkers of phthalates in pregnancy and preterm birth among individuals living in the US. Design, Setting, and Participants: Individual-level data were pooled from 16 preconception and pregnancy studies conducted in the US. Pregnant individuals who delivered between 1983 and 2018 and provided 1 or more urine samples during pregnancy were included. Exposures: Urinary phthalate metabolites were quantified as biomarkers of phthalate exposure. Concentrations of 11 phthalate metabolites were standardized for urine dilution and mean repeated measurements across pregnancy were calculated. Main Outcomes and Measures: Logistic regression models were used to examine the association between each phthalate metabolite with the odds of preterm birth, defined as less than 37 weeks of gestation at delivery (n = 539). Models pooled data using fixed effects and adjusted for maternal age, race and ethnicity, education, and prepregnancy body mass index. The association between the overall mixture of phthalate metabolites and preterm birth was also examined with logistic regression. G-computation, which requires certain assumptions to be considered causal, was used to estimate the association with hypothetical interventions to reduce the mixture concentrations on preterm birth. Results: The final analytic sample included 6045 participants (mean [SD] age, 29.1 [6.1] years). Overall, 802 individuals (13.3%) were Black, 2323 (38.4%) were Hispanic/Latina, 2576 (42.6%) were White, and 328 (5.4%) had other race and ethnicity (including American Indian/Alaskan Native, Native Hawaiian, >1 racial identity, or reported as other). Most phthalate metabolites were detected in more than 96% of participants. Higher odds of preterm birth, ranging from 12% to 16%, were observed in association with an interquartile range increase in urinary concentrations of mono-n-butyl phthalate (odds ratio [OR], 1.12 [95% CI, 0.98-1.27]), mono-isobutyl phthalate (OR, 1.16 [95% CI, 1.00-1.34]), mono(2-ethyl-5-carboxypentyl) phthalate (OR, 1.16 [95% CI, 1.00-1.34]), and mono(3-carboxypropyl) phthalate (OR, 1.14 [95% CI, 1.01-1.29]). Among approximately 90 preterm births per 1000 live births in this study population, hypothetical interventions to reduce the mixture of phthalate metabolite levels by 10%, 30%, and 50% were estimated to prevent 1.8 (95% CI, 0.5-3.1), 5.9 (95% CI, 1.7-9.9), and 11.1 (95% CI, 3.6-18.3) preterm births, respectively. Conclusions and Relevance: Results from this large US study population suggest that phthalate exposure during pregnancy may be a preventable risk factor for preterm delivery

Direct measurement of particle formation and growth from the oxidation of biogenic emissions

International audienceA new facility has been developed to investigate the formation of new particles from the oxidation of volatile organic compounds emitted from vegetation. The facility consists of a biogenic emissions enclosure, an aerosol growth chamber, and the associated instrumentation. Using the facility, new particle formation events have been induced through the reaction of ozone with three different precursor gas mixtures: an ?-pinene test mixture and the emissions of a Holm oak (Quercus ilex) specimen and a loblolly pine (Pinus taeda) specimen. The results demonstrate the variability between species in their potential to form new aerosol products. The emissions of Q. ilex specimen resulted in fewer particles than did ?-pinene, although the concentration of monoterpenes was roughly equal in both experiments before the addition of ozone. Conversely, the oxidation of P. taeda specimen emissions led to the formation of more particles than either of the other two gas mixtures, despite a lower initial terpenoid concentration. These variations can be attributed to differences in the speciation of the vegetative emissions with respect to the ?-pinene mixture and to each other. Specifically, the presence of ?-pinene and other slower-reacting monoterpenes probably inhibited particle formation in the Q. ilex experiment, while the presence of sesquiterpenes, including ?-caryophyllene, in the emissions of the P. taeda specimen were the likely cause of the more intense particle formation events observed during that experiment

Disruption of sitting balance after stroke: influence of spoken output

Objectives: To identify the extent of dual task interference between cognitive and motor tasks, (cognitive motor interference (CMI)) in sitting balance during recovery from stroke; to compare CMI in sitting balance between stroke and non-stroke groups; and to record any changes to CMI during sitting that correlate with functional recovery. Method: 36 patients from stroke rehabilitation settings in three NHS trusts. Healthy control group: 21 older volunteers. Measures of seated postural sway were taken in unsupported sitting positions, alone, or concurrently with either a repetitive utterance task or an oral word category generation task. Outcome measures were variability of sway area, path length of sway, and the number of valid words generated. Results: Stroke patients were generally less stable than controls during unsupported sitting tasks. They showed greater sway during repetitive speech compared with quiet sitting, but did not show increased instability to posture between repetitive speech and word category generation. When compared with controls, stroke patients experienced greater dual task interferences during repetitive utterance but not during word generation. Sway during repetitive speech was negatively correlated with concurrent function on the Barthel ADL index. Conclusions: The stroke patients showed postural instability and poor word generation skills. The results of this study show that the effort of verbal utterances alone was sufficient to disturb postural control early after stroke, and the extent of this instability correlated with concomitant Barthel ADL function

The reform of the Common Agricultural Policy New opportunities for wildlife and the environment; a discussion paper

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