609 research outputs found

    DPY-30 Domain and its Flanking Sequence Mediate the Assembly Modulation of Flagellar Radial Spoke Complexes

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    RIIa is known as the dimerization and docking (D/D) domain of the cyclic AMP (cAMP)-dependent protein kinase. However, numerous molecules, including radial spoke protein 2 (RSP2) in Chlamydomonas flagella, also contain an RIIa or a similar DPY-30 domain. To elucidate new roles of D/D domain-containing proteins, we investigated a panel of RSP2 mutants. An RSP2 mutant had paralyzed flagella defective in RSP2 and multiple subunits near the spokehead. New transgenic strains lacking only the DPY-30 domain in RSP2 were also paralyzed. In contrast, motility was restored in strains that lacked only RSP2’s calmodulin- binding C-terminal region. These cells swam normally in dim light but could not maintain typical swimming trajectories under bright illumination. In both deletion transgenic strains, the subunits near the spokehead were restored, but their firm attachment to the spokestalk required the DPY-30 domain. We postulate that the DPY-30–helix dimer is a conserved two-prong linker, required for normal motility, organizing duplicated subunits in the radial spoke stalk and formation of a symmetrical spokehead. Further, the dispensable calmodulin-binding region appears to fine-tune the spokehead for regulation of “steering” motility in the green algae. Thus, in general, D/D domains may function to localize molecular modules for both the assembly and modulation of macromolecular complexes

    A Versatile Pseudo-Random Noise Generator

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    A detailed design is presented for a digital pseudo-random noise generator. The instrument is built with standard integrated circuits. It produces both binary noise (pseudo-random binary sequences) and white Gaussian noise of variable bandwidth. By setting front panel switches to match tabulated octal codes, one may select a vast number of independent noise programs

    Productivity Growth and Convergence in Crop, Ruminant and Non-Ruminant Production: Measurement and Forecasts

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    There is considerable interest in projections of future productivity growth in agriculture. Whether one is interested in the outlook for global commodity markets, future patterns of international trade, or the interactions between land use, deforestation and ecological diversity, the rate of productivity growth in agriculture is an essential input. Yet solid projections for this variable have proven elusive particularly on a global basis. This is due, in no small part, to the difficulty in measuring historical productivity growth. The purpose of this paper is to report the latest time series evidence on total factor productivity growth for crops, ruminants and non-ruminant livestock, on a global basis. We then follow with tests for convergence amongst regions, providing forecasts for farm productivity growth to the year 2040. The results suggest that most regions in the sample are likely to experience larger productivity gains in livestock than in crops. Within livestock, the non-ruminant sector is expected to continue to be more dynamic than the ruminant sector. Given the rapid rates of productivity growth observed recently, non-ruminant and crop productivity in developing countries may be converging to the productivity levels of developed countries. For ruminants, the results show that productivity levels may be diverging between developed and developing countries.Malmquist index, productivity, convergence, projections, crops, livestock, Productivity Analysis, D24, O13, O47, Q10,

    On school choice and test-based accountability.

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    Among the two most prominent school reform measures currently being implemented in The United States are school choice and test-based accountability. Until recently, the two policy initiatives remained relatively distinct from one another. With the passage of the No Child Left Behind Act of 2001 (NCLB), a mutualism between choice and accountability emerged whereby school choice complements test-based accountability. In the first portion of this study we present a conceptual overview of school choice and test-based accountability and explicate connections between the two that are explicit in reform implementations like NCLB or implicit within the market-based reform literature in which school choice and test-based accountability reside. In the second portion we scrutinize the connections, in particular, between school choice and test-based accountability using a large western school district with a popular choice system in place. Data from three sources are combined to explore the ways in which school choice and test-based accountability draw on each other: state assessment data of children in the district, school choice data for every participating student in the district choice program, and a parental survey of both participants and non-participants of choice asking their attitudes concerning the use of school report cards in the district. Results suggest that choice is of benefit academically to only the lowest achieving students, choice participation is not uniform across different ethnic groups in the district, and parents' primary motivations as reported on a survey for participation in choice are not due to test scores, though this is not consistent with choice preferences among parents in the district. As such, our results generally confirm the hypotheses of choice critics more so than advocates. Keywords: school choice; accountability; student testing

    Ecological Knowledge, Leadership, and the Evolution of Menopause in Killer Whales

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    SummaryClassic life-history theory predicts that menopause should not occur because there should be no selection for survival after the cessation of reproduction [1]. Yet, human females routinely live 30 years after they have stopped reproducing [2]. Only two other species—killer whales (Orcinus orca) and short-finned pilot whales (Globicephala macrorhynchus) [3, 4]—have comparable postreproductive lifespans. In theory, menopause can evolve via inclusive fitness benefits [5, 6], but the mechanisms by which postreproductive females help their kin remain enigmatic. One hypothesis is that postreproductive females act as repositories of ecological knowledge and thereby buffer kin against environmental hardships [7, 8]. We provide the first test of this hypothesis using a unique long-term dataset on wild resident killer whales. We show three key results. First, postreproductively aged females lead groups during collective movement in salmon foraging grounds. Second, leadership by postreproductively aged females is especially prominent in difficult years when salmon abundance is low. This finding is critical because salmon abundance drives both mortality and reproductive success in resident killer whales [9, 10]. Third, females are more likely to lead their sons than they are to lead their daughters, supporting predictions of recent models [5] of the evolution of menopause based on kinship dynamics. Our results show that postreproductive females may boost the fitness of kin through the transfer of ecological knowledge. The value gained from the wisdom of elders can help explain why female resident killer whales and humans continue to live long after they have stopped reproducing

    Andean Land Use And Biodiversity: Humanized Landscapes In A Time Of Change

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    Some landscapes Cannot be understood without reference., to the kinds. degrees, kinds, degrees, and history of human-caused modifications to the Earth's surface. The tropical latitudes of the Andes represent one such place, with agricultural land-use systems appearing in the Early Holocene. Current land use includes both intensive and extensive grazing and crop- or tree-based agricultural systems found across virtually the, entire range of possible elevations and humidity regimes. Biodiversity found in or adjacent to such humanized landscapes will have been altered in abundance. composition, and distribution in relation to the resiliency of the native Species to harvest, hold cover modifications, and other deliberate or inadvertent human land uses. In addition, the geometries of land cover, resulting flout difference among the shapes, sizes, connectivities, and physical structures of the patches, corridors, and matrices that compose landscape mosaics, will constrain biodiversity, often in predictable ways. This article proposes a conceptual model that alter ins that the Continued persistence of native species may depend as much oil the shifting Of Andean landscape mosaics as on species characteristics, themselves. Furthermore, mountains such as the Andes display long gradients of environmental Conditions that after in relation to latitude, soil moisture, aspect, and elevation. Global environmental change will shift these, especially temperature and humidity regimes along elevational gradients, causing Changes outside the historical range of variation for some species. Both land-use systems and Conservation efforts will need to respond spatially to these shifts in the future, at both landscape and regional scales.Geography and the Environmen

    Worldwide use of the first set of physical activity Country Cards: The Global Observatory for Physical Activity - GoPA!

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    Background: The work of The Global Observatory for Physical Activity-GoPA! is the first global effort to compile standardized country-level surveillance, policy and research data for physical activity in order to better understand how countries and regions address promoting physical activity. GoPA! developed standardized country-specific physical activity profiles (“Country Cards”) to summarize country-level data through 2013. The aim of this study was to assess use of the Country Cards, identify the factors associated with their use, and develop recommendations for supporting country-level physical activity promotion. Methods: Cross sectional internet-based survey conducted between August–October 2016. Target study participants were national physical activity leaders and advocates in academia, government and practice from the GoPA! countries, and members of the International Society of Physical Activity and Health. A Country Card use composite score was created based on the diversity and frequency of use. Statistical analyses on the associations between the composite score and respondent characteristics, country characteristics, barriers and opinions were conducted (including descriptive analyses and a logistic regression with robust standard errors). Results: One hundred forty three participants from 68 countries completed the survey. Use of the Country Cards was associated with being part of the GoPA! network, knowing about the Country Cards, and on the stage of country capacity for physical activity promotion. Country Card knowledge varied by country income group, region and the country specific context. More diverse and frequent use of the cards (highest tertile of the composite score for use) was associated with: 1. Being a country contact vs general participant (OR 18.32–95% CI 5.63–59.55, p = 0.002), and 2. Collaborating with a government representative working in NCDs on a monthly or more frequent contact vs less frequent contact (OR 3.39–95% CI 1.00–11.54, P < 0.05). Conclusions: For the Country Cards to have a broader impact, GoPA! will need to widen its reach beyond the academic sector. With further refinement of the cards, and training in their implementation, they could be an important tool for advancing country capacity for contextually-relevant strategies, actions and timelines for PA promotion

    Distinct Mechanisms for Induction and Tolerance Regulate the Immediate Early Genes Encoding Interleukin 1β and Tumor Necrosis Factor α

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    Interleukin-1β and Tumor Necrosis Factor α play related, but distinct, roles in immunity and disease. Our study revealed major mechanistic distinctions in the Toll-like receptor (TLR) signaling-dependent induction for the rapidly expressed genes (IL1B and TNF) coding for these two cytokines. Prior to induction, TNF exhibited pre-bound TATA Binding Protein (TBP) and paused RNA Polymerase II (Pol II), hallmarks of poised immediate-early (IE) genes. In contrast, unstimulated IL1B displayed very low levels of both TBP and paused Pol II, requiring the lineage-specific Spi-1/PU.1 (Spi1) transcription factor as an anchor for induction-dependent interaction with two TLR-activated transcription factors, C/EBPβ and NF-κB. Activation and DNA binding of these two pre-expressed factors resulted in de novo recruitment of TBP and Pol II to IL1B in concert with a permissive state for elongation mediated by the recruitment of elongation factor P-TEFb. This Spi1-dependent mechanism for IL1B transcription, which is unique for a rapidly-induced/poised IE gene, was more dependent upon P-TEFb than was the case for the TNF gene. Furthermore, the dependence on phosphoinositide 3-kinase for P-TEFb recruitment to IL1B paralleled a greater sensitivity to the metabolic state of the cell and a lower sensitivity to the phenomenon of endotoxin tolerance than was evident for TNF. Such differences in induction mechanisms argue against the prevailing paradigm that all IE genes possess paused Pol II and may further delineate the specific roles played by each of these rapidly expressed immune modulators. © 2013 Adamik et al
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