Temporal and spatial variations in freshwater 14C reservoir effects: Lake Myvatn, Northern Iceland

Lake Mývatn is an interior highland lake in northern Iceland that forms a unique ecosystem of international scientific importance and is surrounded by a landscape rich in archaeological and palaeoenvironmental sites. A significant Freshwater 14C Reservoir Effect (FRE) has been identified in carbon from the lake at some Norse (c.870-1000 AD) archaeological sites in the wider region (Mývatnssveit). Previous AMS measurements indicated this FRE was ~1500-1900 14C years. Here we present the results of a study using stable isotope and 14C measurements to quantify the Mývatn FRE for both the Norse and modern periods. This work has identified a temporally variable FRE that is greatly in excess of previous assessments. New, paired samples of contemporaneous bone from terrestrial herbivores and omnivores (including humans) from Norse sites demonstrate at least some omnivore diets incorporated sufficient freshwater resources to result in a herbivore-omnivore age offset of up to 400 14C yrs. Modern samples of benthic detritus, aquatic plants, zooplankton, invertebrates and freshwater fish indicate an FRE in excess of 5000 14C yrs in some species. Likely geothermal mechanisms for this large FRE are discussed, along with implications for both chronological reconstruction and integrated investigation of stable and radioactive isotop

Psychopathological consequences related to problematic Instagram use among adolescents: the mediating role of body image dissatisfaction and moderating role of gender

In a minority of cases, problematic use of technology can negatively impact on adolescents and impair some aspects of their social, emotional, and psychological development. The purpose of the present study was to examine the direct and indirect effects of problematic Instagram use (PIU) on different psychopathological outcomes including loneliness, depression, anxiety, and social anxiety via body image dissatisfaction (BID). Additionally, moderating role of gender on the relationships among variables was investigated. A total of 491 adolescents (Mage = 15.92 years, SDage = 1.07; range = 14 to 19 years) were recruited for the study to complete a questionnaire that included the relevant assessment tools for the aforementioned variables. Mediation and moderation analyses showed that among male adolescents, PIU was directly associated with loneliness, depression, general anxiety, and social anxiety and BID partially mediated these associations. Among females, PIU was directly associated with depression and indirectly with general anxiety and social anxiety via BID. Gender significantly moderated the direct relationships of PIU with loneliness, general anxiety, and social anxiety. PIU was directly associated with loneliness, general anxiety, and social anxiety among males only, whereas among females, PIU was indirectly associated with general and social anxiety via BID but was not related to loneliness. Results of this study indicate that PIU has different negative psychological effects on male and female adolescents and that BID appears to be one explanatory factor for these impairments especially among females

Successful aging as management of resources: The role of selection, optimization, and compensation

One of the central tenets of life-span psychology is that the process of development entails gains and losses that occur over the entire life span. Thus, Paul and Margret Baltes (1990) conceptualized successful aging as a lifelong process of maximizing gains and minimizing losses by means of three processes: selection, optimization, and compensation (SOC). This article reviews empirical studies that have investigated the use of SOC during adulthood with different methodological approaches and have found evidence for the importance of SOC for successfully managing one's resources. The article highlights the importance of prioritizing goals (selection) according to their importance for increasing gains (optimization) and avoiding losses (compensation) in consideration of currently available resources. Age-related changes in resource availability and time perspective can also result in a shift in goal orientation towards gains or losses and in goal focus on the process or the outcome of goal pursuit. Taken together, the action-theoretical approach to the SOC framework suggests that selection, optimization, and compensation can be seen as key concepts for understanding successful aging

0337 Association Between Free-living Sleep and Memory and Attention in Healthy Adolescents

Abstract Introduction Sleep is important for people of all ages, especially children during development. However, adolescents often sleep less than the recommended eight hours per night. Clinical trials have found that even partial sleep deprivation- shorter than the recommended duration- can reduce cognitive function in adolescents. The association between objectively measured free-living sleep and cognition function in adolescents has not been studied. Methods Free-living sleep duration and sleep efficiency were measured over one week with wrist actigraphy in 199 healthy normal adolescents (140 girls, mean±SD, 17.7±0.3 years). The day after the sleep measurement concluded, sustained attention was assessed with a validated Posner cue-target task, and working memory was measured with an n-back task. Associations between sleep measures and response times during attention and memory tasks were explored with multiple linear regression adjusted for task accuracy. Results Over the entire week, participants’ average sleep duration was 6.2±0.7 h/night and average sleep efficiency was 88±4.4% and averages for sleep the night prior to the cognitive testing were similar. Response times on memory (1-back: 420.6±73.9, 2-back: 522.6±101.9, and 3-back: 551.8±137.2 msec) and attention tasks (valid cue: 309±31.2, invalid cue: 365.8±36, and no cue: 393.6±38.9 msec) were similar to previous reports and not associated with average weekly sleep measures. Sleep duration of the night before cognitive testing was negatively associated with response times for the most challenging memory task (3-back; p=0.02). However, sleep measures of the night before did not correlate with any of the attention task scores. Conclusion Our data suggests that performance on difficult memory tasks may be negatively impacted by shorter free-living sleep durations the night prior to testing, even in healthy adolescents who average less than the recommended amount of sleep. Future studies should explore whether recovery sleep or other improvements in sleep habit might mitigate such effects on memory. Support The Eimskip University of Iceland Fund, Icelandic Centre for Research, National Institute of Diabetes and Digestive and Kidney Diseases. </jats:sec

Association between free-living sleep and memory and attention in healthy adolescents

AbstractIn laboratory studies, imposed sleep restriction consistently reduces cognitive performance. However, the association between objectively measured, free-living sleep and cognitive function has not been studied in older adolescents. To address this gap, we measured one week of sleep with a wrist-worn GT3X+ actigraph in 160 adolescents (96 girls, 17.7 ± 0.3 years) followed by assessment of working memory with an n-back task and visual attention with a Posner cue-target task. Over the week, participants spent 7.1 ± 0.8 h/night in bed and slept 6.2 ± 0.8 h/night with 88.5 ± 4.8% efficiency and considerable intra-participant night-to-night variation, with a standard deviation in sleep duration of 1.2 ± 0.7 h. Sleep measures the night before cognitive testing were similar to weekly averages. Time in bed the night before cognitive testing was negatively associated with response times during the most challenging memory task (3-back; p = 0.005). However, sleep measures the night before did not correlate with performance on the attention task and weekly sleep parameters were not associated with either cognitive task. Our data suggests shorter acute free-living sleep may negatively impact difficult memory tasks, however the relationship between free-living sleep and cognitive task performance in healthy adolescents is less clear than that of laboratory findings, perhaps due to high night-to-night sleep variation.</jats:p

Temporal and Spatial Variations in Freshwater 14C Reservoir Effects: Lake Mývatn, Northern Iceland

Lake Mvatn is an interior highland lake in northern Iceland that forms a unique ecosystem of international scientific importance and is surrounded by a landscape rich in archaeological and paleoenvironmental sites. A significant freshwater reservoir effect (FRE) has been identified in carbon from the lake at some Viking (about AD 870?1000) archaeological sites in the wider region (Mvatnssveit). Previous accelerator mass spectrometry (AMS) measurements indicated this FRE was about 1500-1900 14C yr. Here, we present the results of a study using stable isotope and 14C measurements to quantify the Mvatn FRE for both the Viking and modern periods. This work has identified a temporally variable FRE that is greatly in excess of previous assessments. New, paired samples of contemporaneous bone from terrestrial herbivores and omnivores (including humans) from Viking sites demonstrate at least some omnivore diets incorporated sufficient freshwater resources to result in a herbivore-omnivore age offset of up to 400 14C yr. Modern samples of benthic detritus, aquatic plants, zooplankton, invertebrates, and freshwater fish indicate an FRE in excess of 5000 14C yr in some species. Likely geothermal mechanisms for this large FRE are discussed, along with implications for both chronological reconstruction and integrated investigation of stable and radioactive isotopes