Publication date: 1 June 2017
Source:Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 475
Author(s): Longbin Sha, Hui Jiang, Marit-Solveig Seidenkrantz, Dongling Li, Camilla S. Andresen, Karen Luise Knudsen, Yanguang Liu, Meixun Zhao
We present a reconstruction of Holocene sea-ice variability from sediment core GA306-GC3, from the Holsteinsborg Dyb off West Greenland, which provides an index of palaeoceanographic and palaeoenvironmental conditions within this climatically sensitive region during the last 6700yr. The reconstructed sea-ice record, combined with previously published proxy data, suggests that relatively warm conditions with reduced sea-ice extent prior to 5000cal.yrBP were associated with the Holocene Thermal Maximum. Subsequent cooling and extensive sea-ice cover between ca. 5000 and 4000cal.yrBP was followed by even colder conditions and persistent sea-ice cover during the Neoglacial cooling phase, particularly after ca. 1500cal.yrBP. There is a positive correlation between West Greenland sea-ice cover and solar activity over the past 5000yr, but the correlation is much weaker prior to 5000cal.yrBP. In addition, there is a strong link between West Greenland sea ice and changes in the abundance of arctic benthic foraminifera species, related to different water masses of the West Greenland Current during the entire interval, even prior to 5000cal.yrBP. Our findings indicate that sea-ice variability off West Greenland was driven not only by solar activity, but also by ocean circulation (the strength of cold Polar water from the East Greenland Current and warm Atlantic water from the Irminger Current).
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Publication date: 1 June 2017
Source:Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 475
Author(s): Emad I. Elfar, Brooks B. Ellwood, Wei-Hsung Wang, Gorden L. Bell
The Middle Cambrian House Range Embayment (HRE) represents a deep-water incursion into an extensive carbonate platform along the passive margin of western Laurentia. The distribution and source of HRE mixed siliciclastic-carbonate sediments are poorly understood because many key elements were missed during past field observations or coarse correlation. This study describes the HRE complex lithological variations, and improves current understanding concerning the global climatic and sea level fluctuations that drove these variations. Magnetic susceptibility (χ), gamma radiation (GR) and carbonate content (CaCO3%) are used to construct high-resolution correlation among three overlapping Middle Cambrian marine sedimentary sections: 1) the Drumian Global boundary Stratotype Section and Point (GSSP) in the Drum Mountains, western Utah, 2) the Marjum Pass section in the House Range, western Utah, and 3) the Packrat section Great Basin National Park in the Snake Range, eastern Nevada. Middle Cambrian HRE lithological variations followed broad facies patterns. Carbonate sediments dominated the HRE edges and decreased inward, while shale, dominated the HRE trough and decreased outward. The carbonate/detrital ratio varied along the area between the HRE Edge and trough due to; 1) sea level fluctuations, (2) the depositional setting at each section, and 3) the allocyclic, climatic variations that acted on the carbonate platform of western Laurentia. Sea level and climatic fluctuations drove temporal facies variations that are well correlated among the three sections, while the depositional setting for each section drove spatial facies variations that account for carbonate and detrital sediment sources and their trajectories into the HRE. The GSSP is a shallow trough section; Marjum Pass is a lower slope section of the northern HRE ramp; and the Packrat is a lower slope section situated along the southern HRE ramp. Sea level and climatic cycles during the Middle Cambrian Drumian Stage, induced long-term and short-term facies variations, respectively, that were superimposed on each other.
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by Suzanne Maman, Katherine R. Murray, Sue Napierala Mavedzenge, Lennah Oluoch, Florence Sijenje, Kawango Agot, Harsha Thirumurthy
Promoting awareness of serostatus and frequent HIV testing is especially important among high risk populations such as female sex workers (FSW) and their sexual partners. HIV self-testing is an approach that is gaining ground in sub-Saharan Africa as a strategy to increase knowledge of HIV status and promote safer sexual decisions. However, little is known about self-test distribution strategies that are optimal for increasing testing access among hard-to-reach and high risk individuals. We conducted a qualitative study with 18 FSW who participated in a larger study that provided them with five oral fluid-based self-tests, training on how to use the tests, and encouragement to offer the self-tests to their sexual partners using their discretion. Women demonstrated agency in the strategies they used to introduce self-tests to their partners and to avoid conflict with partners. They carefully considered with whom to share self-tests, often assessing the possibility for negative reactions from partners as part of their decision making process. When women faced negative reactions from partners, they drew on strategies they had used before to avoid conflict and physical harm from partners, such as not responding to angry partners and forgoing payment to leave angry partners quickly. Some women also used self-tests to make more informed sexual decisions with their partners.
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by Jeremy Proville, Daniel Zavala-Araiza, Gernot Wagner
We use a parallelized spatial analytics platform to process the twenty-one year totality of the longest-running time series of night-time lights data—the Defense Meteorological Satellite Program (DMSP) dataset—surpassing the narrower scope of prior studies to assess changes in area lit of countries globally. Doing so allows a retrospective look at the global, long-term relationships between night-time lights and a series of socio-economic indicators. We find the strongest correlations with electricity consumption, CO2 emissions, and GDP, followed by population, CH4 emissions, N2O emissions, poverty (inverse) and F-gas emissions. Relating area lit to electricity consumption shows that while a basic linear model provides a good statistical fit, regional and temporal trends are found to have a significant impact.
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by Ying Ding, Encong Wang, Yuchen Zou, Yan Song, Xue Xiao, Wanyi Huang, Yanfang Li
Gender differences in feedback processing have been observed among adolescents and adults through event-related potentials. However, information on whether and how this feedback processing is affected by feedback valence, feedback type, and individual sensitivity in reward/punishment among children remains minimal. In this study, we used a guessing game task coupled with electroencephalography to investigate gender differences in feedback processing, in which feedback to reward and punishment was presented in the context of monetary and social conditions. Results showed that boys were less likely to switch their response after punishment, had generally less feedback-related negativity (FRN) amplitude, and longer FRN latency in monetary and punishment conditions than girls. Moreover, FRN for monetary punishment, which is related to individual difference in reward sensitivity, was observed only in girls. The study provides gender-specific evidence for the neural processing of feedback, which may offer educational guidance for appropriate feedback for girls and boys.
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by Lydia T. S. Yee
Words are frequently used as stimuli in cognitive psychology experiments, for example, in recognition memory studies. In these experiments, it is often desirable to control for the words’ psycholinguistic properties because differences in such properties across experimental conditions might introduce undesirable confounds. In order to avoid confounds, studies typically check to see if various affective and lexico-semantic properties are matched across experimental conditions, and so databases that contain values for these properties are needed. While word ratings for these variables exist in English and other European languages, ratings for Chinese words are not comprehensive. In particular, while ratings for single characters exist, ratings for two-character words—which often have different meanings than their constituent characters, are scarce. In this study, ratings for 292 two-character Chinese nouns were obtained from Cantonese speakers in Hong Kong. Affective variables, including valence and arousal, and lexico-semantic variables, including familiarity, concreteness, and imageability, were rated in the study. The words were selected from a film subtitle database containing word frequency information that could be extracted and listed alongside the resulting ratings. Overall, the subjective ratings showed good reliability across all rated dimensions, as well as good reliability within and between the different groups of participants who each rated a subset of the words. Moreover, several well-established relationships between the variables found consistently in other languages were also observed in this study, demonstrating that the ratings are valid. The resulting word database can be used in studies where control for the above psycholinguistic variables is critical to the research design.
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by Natalia Jaworska, Sylvia M. Cox, Kevin F. Casey, Isabelle Boileau, Mariya Cherkasova, Kevin Larcher, Alain Dagher, Chawki Benkelfat, Marco Leyton
Novelty-seeking (NS) and impulsive personality traits have been proposed to reflect an interplay between fronto-cortical and limbic systems, including the limbic striatum (LS). Although neuroimaging studies have provided some evidence for this, most are comprised of small samples and many report surprisingly large effects given the challenges of trying to relate a snapshot of brain function or structure to an entity as complex as personality. The current work tested a priori hypotheses about associations between striatal dopamine (DA) release, cortical thickness (CT), and NS in a large sample of healthy adults.
Fifty-two healthy adults (45M/7F; age: 23.8±4.93) underwent two positron emission tomography scans with [11C]raclopride (specific for striatal DA D2/3 receptors) with or without amphetamine (0.3 mg/kg, p.o.). Structural magnetic resonance image scans were acquired, as were Tridimensional Personality Questionnaire data. Amphetamine-induced changes in [11C]raclopride binding potential values (ΔBPND) were examined in the limbic, sensorimotor (SMS) and associative (AST) striatum. CT measures, adjusted for whole brain volume, were extracted from the dorsolateral sensorimotor and ventromedial/limbic cortices.
BPND values were lower in the amphetamine vs. no-drug sessions, with the largest effect in the LS. When comparing low vs. high LS ΔBPND groups (median split), higher NS2 (impulsiveness) scores were found in the high ΔBPND group. Partial correlations (age and gender as covariates) yielded a negative relation between ASTS ΔBPND and sensorimotor CT; trends for inverse associations existed between ΔBPND values in other striatal regions and frontal CT. In other words, the greater the amphetamine-induced striatal DA response, the thinner the frontal cortex.
These data expand upon previously reported associations between striatal DA release in the LS and both NS related impulsiveness and CT in the largest sample reported to date. The findings add to the plausibility of these associations while suggesting that the effects are likely weaker than has been previously proposed.
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