703 research outputs found
Plastics and the Environment
Plastics are persistent and pervasive throughout the environment and have now been reported from the deepest parts of the ocean to the tops of the highest and most remote mountains. There is a body of information on the sources, degradation, and transport of plastics as well as a variety of research investigating the ecotoxicological and wider ecological consequences of plastic ingestion and accumulation. Such knowledge has been obtained with developments in field and laboratory methods for plastic identification and then well-publicized in the media and wider public communications. However, although there has been a large focus on plastic pollution within the past decade, there is plenty that we do not yet know. Even within the past five years, sources of microplastics (1 ÎŒmâ5 mm) to the environment have been confirmed that had not previously been considered, for example, road paints and tire wear particles. Initial research focused on plastic in the marine environment, but understanding on the accumulation and impacts in terrestrial and freshwater environments is growing. There is a substantial lack of basic science focused on the efficiency of solutions aimed at mitigating plastic pollution. This review highlights some recent (past five years) research on plastics in the environment, including investigations in accumulation, sources, distribution, impacts, solutions and provides directions for future work. </jats:p
Environmental Deterioration of Biodegradable, Oxo-biodegradable, Compostable, and Conventional Plastic Carrier Bags in the Sea, Soil, and Open-Air Over a 3-Year Period
There
is clear evidence that discarded single-use carrier bags
are accumulating in the environment. As a result, various plastic
formulations have been developed which state they deteriorate faster
and/or have fewer impacts on the environment because their persistence
is shorter. This study examined biodegradable, oxo-biodegradable,
compostable, and high-density polyethylene (i.e., a conventional plastic
carrier bag) materials over a 3 year period. These materials were
exposed in three natural environments; open-air, buried in soil, and
submersed in seawater, as well as in controlled laboratory conditions.
In the marine environment, the compostable bag completely disappeared
within 3 months. However, the same compostable bag type was still
present in the soil environment after 27 months but could no longer
hold weight without tearing. After 9 months exposure in the open-air,
all bag materials had disintegrated into fragments. Collectively,
our results showed that none of the bags could be relied upon to show
any substantial deterioration over a 3 year period in all of the environments.
It is therefore not clear that the oxo-biodegradable or biodegradable
formulations provide sufficiently advanced rates of deterioration
to be advantageous in the context of reducing marine litter, compared
to conventional bags
Characterisation, Quantity and Sorptive Properties of Microplastics Extracted From Cosmetics
Cosmetic products, such as facial scrubs, have been identified as potentially important primary sources of microplastics to the marine environment. This study characterises, quantifies and then investigates the sorptive properties of plastic microbeads that are used as exfoliants in cosmetics. Polyethylene microbeads were extracted from several products, and shown to have a wide size range (mean diameters between 164 to 327 ÎŒm). We estimated that between 4594 â 94500 microbeads could be released in a single use. To examine the potential for microbeads to accumulate and transport chemicals they were exposed to a binary mixture of 3H-phenanthrene and 14C-DDT in seawater. The potential for transport of sorbed chemicals by microbeads was broadly similar to that of polythene (PE) particles used in previous sorption studies. In conclusion, cosmetic exfoliants are a potentially important, yet preventable source of microplastic contamination in the marine environment
How CrossâExamination on Subjectivity and Bias Affects Jurorsâ Evaluations of Forensic Science Evidence
Contextual bias has been widely discussed as a possible problem in forensic science. The trial simulation experiment reported here examined reactions of jurors at a county courthouse to crossâexamination and arguments about contextual bias in a hypothetical case. We varied whether the key prosecution witness (a forensic odontologist) was crossâexamined about the subjectivity of his interpretations and about his exposure to potentially biasing taskâirrelevant information. Jurors found the expert less credible and were less likely to convict when the expert admitted that his interpretation rested on subjective judgment, and when he admitted having been exposed to potentially biasing taskâirrelevant contextual information (relative to when these issues were not raised by the lawyers). The findings suggest, however, that forensic scientists can immunize themselves against such challenges and maximize the weight jurors give their evidence by adopting context management procedures that blind them to taskâirrelevant information
Dynamics of the power-duration relationship during prolonged endurance exercise and influence of carbohydrate ingestion
This is the author accepted manuscript. The final version is available from the American Physiological Society via the DOI in this recordWe tested the hypotheses that the parameters of the power-duration relationship, estimated as the end-test power (EP) and work done above EP (WEP) during a 3-min all out exercise test (3MT), would be reduced progressively following 40 min, 80 min and 2 h of heavy-intensity cycling, and that carbohydrate (CHO) ingestion would attenuate the reduction in EP and WEP. Sixteen participants completed a 3MT without prior exercise (control), immediately after 40 min, 80 min and 2-h of heavy-intensity exercise while consuming a placebo beverage, and also after 2-h of heavy-intensity exercise while consuming a CHO supplement (60 g/h CHO). There was no difference in EP measured without prior exercise (260 ± 37 W) compared to EP following 40 min (268 ± 39 W) or 80 min (260 ± 40 W) of heavy-intensity exercise; however, after 2-h, EP was 9% lower compared to control (236 ± 47 W; P<0.05). There was no difference in WEP measured without prior exercise (17.9 ± 3.3 kJ) compared to after 40 min of heavy-intensity exercise (16.1 ± 3.3 kJ), but WEP was lower (P<0.05) than control after 80 min (14.7 ± 2.9 kJ) and 2-h (13.8 ± 2.7 kJ). Compared to placebo, CHO ingestion negated the reduction of EP following 2-h of heavy-intensity exercise (254 ± 49 W) but had no effect on WEP (13.5 ± 3.4 kJ). These results reveal a different time course for the deterioration of EP and WEP during prolonged endurance exercise and indicate that EP is sensitive to CHO availability
Atypical Development of Brocaâs Area in a Large Family with Inherited Stuttering
Developmental stuttering is a condition of speech dysfluency, characterised by pauses, blocks, prolongations, and sound or syllable repetitions. It affects around 1% of the population, with potential detrimental effects on mental health and long-term employment. Accumulating evidence points to a genetic aetiology, yet gene-brain associations remain poorly understood due to a lack of MRI studies in affected families. Here we report the first neuroimaging study of developmental stuttering in a family with autosomal dominant inheritance of persistent stuttering.
We studied a four-generation family, sixteen family members were included in genotyping analysis. T1-weighted and diffusion weighted MRI scans were conducted on seven family members (6 male; aged 9â63âyears) with two age and sex matched controls without stuttering (Nâ=â14). Using Freesurfer, we analysed cortical morphology (cortical thickness, surface area and local gyrification index) and basal ganglia volumes. White matter integrity in key speech and language tracts (i.e. frontal aslant tract and arcuate fasciculus) was also analysed using MRtrix and probabilistic tractography.
We identified a significant age by group interaction effect for cortical thickness in the left hemisphere pars opercularis (Brocaâs area). In affected family members this region failed to follow the typical trajectory of age-related thinning observed in controls. Surface area analysis revealed the middle frontal gyrus region was reduced bilaterally in the family (all cortical morphometry significance levels set at a vertex-wise threshold of pâ<â0.01, corrected for multiple comparisons). Both the left and right globus pallidus were larger in the family than in the control group (left pâ=â0.017; right p=0.037), and a larger right globus pallidus was associated with more severe stuttering (rho =0.86, p=0.01). No white matter differences were identified. Genotyping identified novel loci on chromosomes 1 and 4 that map with the stuttering phenotype.
Our findings denote disruption within the cortico-basal ganglia-thalamo-cortical network. The lack of typical development of these structures reflects the anatomical basis of the abnormal inhibitory control network between Brocaâs area and the striatum underpinning stuttering in these individuals. This is the first evidence of a neural phenotype in a family with an autosomal dominantly inherited stuttering
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