1,323 research outputs found
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Floodplain environmental change during the younger dryas and holocene: Evidence from the lower kennet valley, south central England
Many lowland rivers across northwest Europe exhibit broadly similar behavioural responses to glacial-interglacial transitions and landscape development. Difficulties exist in assessing these, largely because the evidence from many rivers remains limited and fragmentary. Here we address this issue in the context of the river Kennet, a tributary of the Thames, since c. 13,000 cal. BP). Some similarities with other rivers are present, suggesting that regional climatic shifts are important controls. The Kennet differs from the regional pattern in a number of ways. The rate of response to sudden climatic change, particularly at the start of the Holocene and also mid-Holocene forest clearance, appears very high. This may reflect abrupt shifts between two catchment scale hydrological states arising from contemporary climates, land use change and geology. Stadial hydrology is dominated by nival regimes, with limited winter infiltration and high spring and summer runoff. Under an interglacial climate, infiltration is more significant. The probable absence of permafrost in the catchment means that a lag between the two states due to its gradual decay is unlikely. Palaeoecology, supported by radiocarbon dates, suggests that, at the very start of the Holocene, a dramatic episode of fine sediment deposition across most of the valley floor occurred, lasting 500-1000 years. A phase of peat accumulation followed as mineral sediment supply declined. A further shift led to tufa deposition, initially in small pools, then across the whole floodplain area, with the river flowing through channels cut in tufa and experiencing repeated avulsion. Major floods, leaving large gravel bars that still form positive relief features on the floodplain, followed mid-Holocene floodplain stability. Prehistoric deforestation is likely to be the cause of this flooding, inducing a major environmental shift with significantly increased surface runoff. Since the Bronze Age, predominantly fine sediments were deposited along the valley with apparently stable channels and vertical floodplain accretion associated with soil erosion and less catastrophic flooding. The Kennet demonstrates that, while a general pattern of river behaviour over time, within a region, may be identifiable, individual rivers are likely to diverge from this. Consequently, it is essential to understand catchment controls, particularly the relative significance of surface and subsurface hydrology
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Situating multimodal learning analytics
The digital age has introduced a host of new challenges and opportunities for the learning sciences community. These challenges and opportunities are particularly abundant in multimodal learning analytics (MMLA), a research methodology that aims to extend work from Educational Data Mining (EDM) and Learning Analytics (LA) to multimodal learning environments by treating multimodal data. Recognizing the short-term opportunities and longterm challenges will help develop proof cases and identify grand challenges that will help propel the field forward. To support the field's growth, we use this paper to describe several ways that MMLA can potentially advance learning sciences research and touch upon key challenges that researchers who utilize MMLA have encountered over the past few years
Physical parameters of a relativistic jet at very high redshift: the case of the blazar J1430+4204
Context. The high-redshift (z = 4.72) blazar J1430+4204 produced a major
radio outburst in 2005. Such outbursts are usually associated with the
emergence of a new component in the inner radio jet. Aims. We searched for
possible changes in the radio structure on milli-arcsecond angular scales, to
determine physical parameters that characterise the relativistic jet ejected
from the centre of this source. Methods. We analysed 15-GHz radio
interferometric images obtained with the Very Long Baseline Array (VLBA) before
and after the peak of the outburst. Results. We did not identify any
significant new jet component over a period of 569 days. We estimated the
Doppler factor, the Lorentz factor, and the apparent transverse speed of a
putative jet component using three different methods. The likely small jet
angle to the line of sight and our values of the apparent transverse speed are
consistent with not detecting a new jet feature.Comment: (6 pages, 4 figures) accepted for publication in Astronomy and
Astrophysic
Types and correlates of school non-attendance in students with autism spectrum disorders
School non-attendance in autism spectrum disorders (ASD) has received very little attention to date. The study aimed to provide a comprehensive description of school non-attendance in students with ASD. Through an online survey, parents of 486 children (mean age 11 years) reported on school attendance over one month, and reasons for instances of non-attendance. On average, students missed five days of school of a possible 23 days. Persistent non-attendance (absent on 10%+ of available sessions) occurred among 43% of students. School non-attendance was associated with child older age, not living in a two-parent household, parental unemployment and, especially, attending a mainstream school. School refusal accounted for 43% of non-attendance. School exclusion and school withdrawal each accounted for 9% of absences. Truancy was almost non-existent. Non-problematic absenteeism (mostly related to medical appointments and illness) accounted for 32% of absences. Non-problematic absenteeism was more likely among those with intellectual disability, school refusal was more likely among older students, and school exclusion was more likely among students from single-parent, unemployed, and well educated households. Findings suggest school non-attendance in ASD is a significant issue, and that it is important to capture detail about attendance patterns and reasons for school non-attendance
Who cooks from scratch and how do they prepare food
Purpose – There is increasing interest in the domestic preparation of food and with the postulated health benefits of “cooking from scratch”. The purpose of this paper is to examine the demographic and food preparation associations of this term in order to examine its operational value. Design/methodology/approach – A national online survey was conducted during 2012 in Australia among 1,023 domestic food providers, half of whom were men. Questions were asked about cooking from scratch, demographic characteristics, food preparation practices and interest in learning about cooking. Findings – Three quarters of the sample reported they often or always “cooked from scratch” (CFS). More women than men always CFS; fewer 18-29 year olds did so often or always but more of the over 50s always did so; fewer single people CFS than cohabiting people. No statistically significant ethnic, educational background or household income differences were found. High levels of cooking from scratch were associated with interest in learning more about cooking, greater use of most cooking techniques (except microwaves), meat and legume preparation techniques, and the use of broader ranges of herbs, spice, liquids/ sauces, other ingredients and cooking utensils. Research limitations/implications – In future work a numerical description of the frequency of cooking from scratch should be considered along with a wider range of response options. The data were derived from an online panel from which men were oversampled. Caution is required in comparisons between men and women respondents. The cross-sectional nature of the sample prevents any causal attributions from being drawn from the observed relationships. Further replication of the findings, especially the lack of association with educational background should be conducted. Originality/value – This is the first study to examine the associations of demographic characteristics and cooking practices with cooking from scratch. The findings suggest that cooking from scratch is common among Australian family food providers and signifies interest in learning about cooking and involvement in a wide range of cooking techniques
Biophysical, thermo-physiological and perceptual determinants of cool-seeking behaviour during exercise in younger and older women
Women continue to be under-represented in thermoregulatory research despite their undergoing unique physiological changes across the lifespan. This study investigated the biophysical, thermo-physiological, and perceptual determinants of cool-seeking behaviour during exercise in younger and older women. Eleven younger (25 ± 5 years; 1.7 ± 0.1 m; 63.1 ± 5.2 kg) and 11 older women (53 ± 6 years; 1.7 ± 0.1 m; 65.4 ± 13.9 kg) performed a 40-min incremental cycling test in a thermoneutral environment (22 ± 1.7°C; 36 ± 4% relative humidity). Throughout the test, participants freely adjusted the temperature of a cooling probe applied to their wrists to offset their thermal discomfort. We continuously recorded the probe–wrist interface temperature to quantify participants’ cool-seeking behaviour. We also measured changes in participants’ rate of metabolic heat production, core and mean skin temperatures, and skin wetness. Finally, we body-mapped participants’ skin heat, cold and wetness sensitivity. Our results indicated that: (1) older and younger women exhibited similar onset and magnitude of cool-seeking behaviour, despite older women presented reduced autonomic heat-dissipation responses (i.e., whole-body sweat losses); (2) older women's thermal behaviour was less determined by changes in core temperature (this being a key driver in younger women), and more by changes in multiple thermo-physiological and biophysical parameters (i.e., physical skin wetness, temperature and heat production); (3) older women did not present lower regional skin thermal and wetness sensitivity than younger women. We conclude that predictions of female cool-seeking behaviours based on thermo-physiological variables should consider the effects of ageing. These findings are relevant for the design of wearable cooling systems and sports garments that meet the thermal needs of women across the lifespan
Factors influencing fruit and vegetable intake among urban Fijians: A qualitative study.
Low fruit and vegetable intake is an important risk factor for micronutrient deficiencies and non-communicable diseases, but many people worldwide, including most Fijians, eat less than the World Health Organization recommended amount. The present qualitative study explores factors that influence fruit and vegetable intake among 57 urban Fijians (50 women, 7 men) of indigenous Fijian (iTaukei) and South Asian (Indian) descent. Eight focus group discussions were held in and around Suva, Fiji's capital and largest urban area, which explored motivation for eating fruit and vegetables, understandings of links to health and disease, availability and sources, determinants of product choice, and preferred ways of preparing and eating fruit and vegetables. Data were analysed using thematic content analysis. Regardless of ethnicity, participants indicated that they enjoyed and valued eating fruit and vegetables, were aware of the health benefits, and had confidence in their cooking skills. In both cultures, fruit and vegetables were essential components of traditional diets. However, increasing preferences for processed and imported foods, and inconsistent availability and affordability of high-quality, low-priced, fresh produce, were identified as important barriers. The findings indicate that efforts to improve fruit and vegetable intake in urban Fijians should target the stability of the domestic fruit and vegetable supply and access
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