2,605 research outputs found

    Alkali oxide-tantalum, niobium and antimony oxide ionic conductors

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    The phase equilibrium relations of four systems were investigated in detail. These consisted of sodium and potassium antimonates with antimony oxide and tantalum and niobium oxide with rubidium oxide as far as the ratio 4Rb2O:llB2O5 (B=Nb, Ta). The ternary system NaSbO3-Sb2O4-NaF was investigated extensively to determine the actual composition of the body centered cubic sodium antimonate. Various other binary and ternary oxide systems involving alkali oxides were examined in lesser detail. The phases synthesized were screened by ion exchange methods to determine mobility of the mobility of the alkali ion within the niobium, tantalum or antimony oxide (fluoride) structural framework. Five structure types warranted further investigation; these structure types are (1) hexagonal tungsten bronze (HTB), (2) pyrochlore, (3) the hybrid HTB-pyrochlore hexagonal ordered phases, (4) body centered cubic antimonates and (5) 2K2O:3Nb2O5. Although all of these phases exhibit good ion exchange properties only the pyrochlore was prepared with Na(+) ions as an equilibrium phase and as a low porosity ceramic. Sb(+3) in the channel interferes with ionic conductivity in this case, although relatively good ionic conductivity was found for the metastable Na(+) ion exchanged analogs of RbTa2O5F and KTaWO6 pyrochlore phases

    Entropy trade-offs in artistic design: A case study of Tamil kolam

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    Limited scope for group coordination in stylistic variations of kolam art

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    In large, complex societies, assorting with others with similar social norms or behaviors can facilitate successful coordination and cooperation. The ability to recognize others with shared norms or behaviors is thus assumed to be under selection. As a medium of communication, human art might reflect fitness-relevant information on shared norms and behaviors of other individuals thus facilitating successful coordination and cooperation.Distinctive styles or patterns of artistic design could signify migration history, different groups with a shared interaction history due to spatial proximity, as well as individual-level expertise and preferences. In addition, cultural boundaries may be even more pronounced in a highly diverse and socially stratified society. In the current study, we focus on a large corpus of an artistic tradition called kolam that is produced by women from Tamil Nadu in South India (N = 3,139 kolam drawings from 192 women) to test whether stylistic variations in art can be mapped onto caste boundaries, migration and neighborhoods. Since the kolam art system with its sequential drawing decisions can be described by a Markov process, we characterize variation in styles of art due to different facets of an artist's identity and the group affiliations, via hierarchical Bayesian statistical models.Our results reveal that stylistic variations in kolam art only weakly map onto caste boundaries, neighborhoods, and regional origin. In fact, stylistic variations or patterns in art are dominated by artist-level variation and artist expertise. Our results illustrate that although art can be a medium of communication, it is not necessarily marked by group affiliation. Rather, artistic behaviour in this context seems to be primarily a behavioral domain within which individuals carve out a unique niche for themselves to differentiate themselves from others. Our findings inform discussions on the evolutionary role of art for group coordination by encouraging researchers to use systematic methods to measure the mapping between specific objects or styles onto groups

    Cardiac adaptations from 4 weeks of intensity-controlled vigorous exercise are lost after a similar period of detraining

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    Intensityā€controlled (relative to VO2max) treadmill exercise training in adult rats results in the activation and ensuing differentiation of endogenous cā€kitpos cardiac stem/progenitor cells (eCSCs) into newly formed cardiomyocytes and capillaries. Whether these trainingā€induced adaptations persist following detraining is undetermined. Twelve male Wistar rats (~230 g) were exercised at 80ā€“85% of their VO2max for 30 min dayāˆ’1, 4 days weekāˆ’1 for 4 weeks (TR; n = 6), followed by 4 weeks of detraining (DTR; n = 6). Twelve untrained rats acted as controls (CTRL). Exercise training significantly enhanced VO2max (11.34 mL kgāˆ’1 mināˆ’1) and wet heart weight (29%) above CTRL (P < 0.05). Echocardiography revealed that exercise training increased LV mass (~32%), posterior and septal wall thickness (~15%), ejection fraction and fractional shortening (~10%) compared to CTRL (P < 0.05). Cardiomyocyte diameter (17.9 Ā± 0.1 Ī¼m vs. 14.9 Ā± 0.6 Ī¼m), newly formed (BrdUpos/Ki67pos) cardiomyocytes (7.2 Ā± 1.3%/1.9 Ā± 0.7% vs. 0.2 Ā± 0.1%/0.1 Ā± 0.1%), total cardiomyocyte number (45.6 Ā± 0.6 Ɨ 106 vs. 42.5 Ā± 0.4 Ɨ 106), cā€kitpos eCSC number (884 Ā± 112 per 106 cardiomyocytes vs. 482 Ā± 132 per 106 cardiomyocytes), and capillary density (4123 Ā± 227 per mm2 vs. 2117 Ā± 118 per mm2) were significantly greater in the LV of trained animals (P < 0.05) than CTRL. Detraining removed the stimulus for cā€kitpos eCSC activation (640 Ā± 98 per 106 cardiomyocytes) and resultant cardiomyocyte hyperplasia (0.4 Ā± 0.3% BrdUpos/0.2 Ā± 0.2% Ki67pos cardiomyocytes). Capillary density (3673 Ā± 374 per mm2) and total myocyte number (44.7 Ā± 0.5 Ɨ 106) remained elevated following detraining, but cardiomyocyte hypertrophy (15.0 Ā± 0.4 Ī¼m) was lost, resulting in a reduction of anatomical (wall thickness ~4%; LV mass ~10% and cardiac mass ~8%, above CTRL) and functional (EF & FS ~2% above CTRL) parameters gained through exercise training. These findings demonstrate that cardiac adaptations, produced by 4 weeks of intensityā€controlled exercise training are lost after a similar period of detraining

    Cooperation across Organizational Boundaries: Experimental Evidence from a Major Sustainability Science Project

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    Engaged research emphasizes researcherā€“stakeholder collaborations as means of improving the relevance of research outcomes and the chances for science-based decision-making. Sustainability science, as a form of engaged research, depends on the collaborative abilities and cooperative tendencies of researchers. We use an economic experiment to measure cooperation between university faculty, local citizens, and faculty engaged in a large sustainability science project to test a set of hypotheses: (1) faculty on the sustainability project will cooperate more with local residents than non-affiliated faculty, (2) sustainability faculty will have the highest level of internal cooperation of any group, and (3) that cooperation may vary due to academic training and culture in different departments amongst sustainability faculty. Our results demonstrate that affiliation with the sustainability project is not associated with differences in cooperation with local citizens or with in-group peers, but that disciplinary differences amongst sustainability faculty do correlate with cooperative tendencies within our sample. We also find that non-affiliated faculty cooperated less with each other than with faculty affiliated with the sustainability project. We conclude that economic experiments can be useful in discovering patterns of prosociality within institutional settings, and list challenges for further applications

    Soil carbon pools are affected by species identity and productivity in a tree common garden experiment

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    The formation and turnover of soil organic carbon (C), the largest terrestrial C pool, is strongly impacted by the ultimate source of that C: leaves, wood, roots, and root exudates. The quantity and quality of these inputs is determined by the identity of the plants involved. Yet substantial uncertainty surrounds the complex relationships among plant traits and soil C, precluding efforts to maximize whole-ecosystem C uptake in nature-based climate mitigation scenarios. In this study, we leveraged a biodiversity-ecosystem function experiment with trees (IDENT) to explore the effects of interspecific variation in plant traits on soil C dynamics in the very early stages of stand development (9 years since planting). Mineral soil C stocks to 5 cm depth were quantified in monospecific plots of 19 tree species planted on a former agricultural field, and analyzed in relation to tree growth and functional traits. We found that tree species identity affected soil bulk density and, to a lesser extent, the carbon content of the topsoil, and thereby total C pools. Among species and across plots, mineral soil C stocks were positively correlated with rates of tree growth and were significantly larger beneath broadleaf trees with ā€œfastā€ functional traits vs. conifers with more conservative leaf traits, when comparisons were made over equivalent soil depth increments. Thus, plant functional traits mediate interspecific differences in productivity, which in turn influence the magnitude of belowground C stocks. These results highlight important linkages between above- and belowground carbon cycles in the earliest stages of afforestation

    White-tailed deer (Odocoileus virginianus) positively affect the growth of mature northern red oak (Quercus rubra) trees

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    Understanding and predicting the effects of deer (Cervidae) on forest ecosystems present significant challenges in ecosystem ecology. Deer herbivory can cause large changes in the biomass and species composition of forest understory plant communities, including early life-cycle trees (i.e., seedlings and saplings). Such changes can impact juvenile to adult transitions and the future age structure and species composition of mature forests. Changes to understory vegetation also impact flow of energy and nutrients in forest ecosystems. Studies examining the influence of deer on mature trees, however, are rare and rely on extrapolating effects from early life cycle stages of trees. We tested the hypothesis that the absence of deer would result in an increase in the growth rate of mature trees by examining the impact of white-tailed deer (Odocoileus virginianus) on mature canopy trees. We examined incremental growth in individuals of Quercus rubra, an important component of temperate deciduous forests in North America, inside and outside 16-year deer exclosures in eastern U.S. deciduous forests. We found that adult trees inside exclosures grew less than those directly exposed to deer. Our findings highlight the indirect effects of white-tailed deer on the growth of adult individuals of Q. rubra in a way opposite of what would be expected from previous studies based on immature or understory tree populations. We suggest the increased growth of adult trees in the presence of deer may be explained by increased nutrient inputs through deer fecal and urine deposits and the alteration of the competitive environment belowground through the reduction of understory vegetation by browsing. Underscoring the ecological and demographic importance of adult trees in forest ecosystems, results from this study suggest the direct and indirect effects of deer on mature trees should not be overlooked

    Physical Education and Blood Lipid Concentrations in Children: The LOOK Randomized Cluster Trial

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    BACKGROUND AND OBJECTIVES Elevated blood lipids during childhood are predictive of dyslipidemia in adults. Although obese and inactive children have elevated values, any potentially protective role of elementary school physical education is unknown. Our objective was to determine the effect of a modern elementary school physical education (PE) program on the blood lipid concentrations in community-based children. METHODS In this cluster-randomized controlled trial, 708 healthy children (8.1Ā±0.3 years, 367 boys) in 29 schools were allocated to either a 4-year intervention program of specialist-taught PE (13 schools) or to a control group of the currently practiced PE conducted by generalist classroom teachers. Fasting blood lipids were measured at ages 8, 10, and 12 years and intervention and control class activities were recorded. RESULTS Intervention classes included more fitness work and more moderate and vigorous physical activity than control classes (both p3.36mmol.L(-1),130 mg/dL) was lower in the intervention than control group (14% vs. 23%, pā€Š=ā€Š0.02). There was also an intervention effect on mean LDL-C across all boys (reduction of 9.6% for intervention v 2.8% control, pā€Š=ā€Š0.02), but not girls (pā€Š=ā€Š0.2). The intervention effect on total cholesterol mirrored LDL-C, but there were no detectable 4-year intervention effects on high-density lipoprotein cholesterol or triglycerides. CONCLUSIONS The PE program delivered by specialist teachers over four years in elementary school reduced the incidence of elevated LDL-C in boys and girls, and provides a means by which early preventative practices can be offered to all children. TRIAL REGISTRATION Australia New Zealand Clinical Trial Registry ANZRN12612000027819 https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=347799.Sources of funding were The Commonwealth Education Trust (New Zealand House, London, UK) (http://www.commonwealth.org.uk/) and the Canberra Hospital Salaried Staff Specialists Fund (http://healthresearch.anu.edu.au/documents/PPFVACATION/ppf-major-info-2012.pdf). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
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