350 research outputs found
Evolution of China's U.S. Policy (1965-72): Prelude to the Economic Reform?
China embarked on its grand economic reform in 1978, and the resulting economic performance has impressive by any standard. Many have accredited China's apparent success to the "gradualism" or patience in its reform agenda. But equally important is China's reform "sequence", which began in staple food production before spreading to other sectors of the economy. What has been absent in the literature is the explanation of why China started with the staple food sector, and why China embarked on the reform in the first place. This study traces China's early reform (the agricultural production) to her realization and abandonment of the self-reliant agriculture policy in the early 1970s. This self-reliance had been China's central ideology and main objective since the 1950s. We study China's attitude towards the U.S. via the line-struggle between different fractions within the Chinese Communist party during this period (1965-72). We further quantify the evolution of China's U.S. policy by examining the anti-U.S. propaganda in Chinese publications
Light incoherence due to quantum-gravitational fluctuations of the background space
Based on the theory of mutual coherence of light from an extended incoherent
quasi-monochromatic source (providing a basis of stellar interferometry) we
estimate the degree of light incoherence due to quantum-gravitational
fluctuations of the background metric. It is shown that the stellar
interferometry observational data considered in the literature for a last few
years as a manifestation against the Planck scale quantum-gravitational
fluctuations of the background metric have no chance for detecting such an
effect.Comment: 5 pages; Version to appear in Astroparticle Physic
Engineering a Model Cell for Rational Tuning of GPCR Signaling.
G protein-coupled receptor (GPCR) signaling is the primary method eukaryotes use to respond to specific cues in their environment. However, the relationship between stimulus and response for each GPCR is difficult to predict due to diversity in natural signal transduction architecture and expression. Using genome engineering in yeast, we constructed an insulated, modular GPCR signal transduction system to study how the response to stimuli can be predictably tuned using synthetic tools. We delineated the contributions of a minimal set of key components via computational and experimental refactoring, identifying simple design principles for rationally tuning the dose response. Using five different GPCRs, we demonstrate how this enables cells and consortia to be engineered to respond to desired concentrations of peptides, metabolites, and hormones relevant to human health. This work enables rational tuning of cell sensing while providing a framework to guide reprogramming of GPCR-based signaling in other systems.BBSR
Genetic variation at MECOM, TERT, JAK2 and HBS1L-MYB predisposes to myeloproliferative neoplasms
Clonal proliferation in myeloproliferative neoplasms (MPN) is driven by somatic mutations in JAK2, CALR or MPL, but the contribution of inherited factors is poorly characterized. Using a three-stage genome-wide association study of 3,437 MPN cases and 10,083 controls, we identify two SNPs with genome-wide significance in JAK2V617F-negative MPN: rs12339666 (JAK2; meta-analysis P=1.27 × 10−10) and rs2201862 (MECOM; meta-analysis P=1.96 × 10−9). Two additional SNPs, rs2736100 (TERT) and rs9376092 (HBS1L/MYB), achieve genome-wide significance when including JAK2V617F-positive cases. rs9376092 has a stronger effect in JAK2V617F-negative cases with CALR and/or MPL mutations (Breslow–Day P=4.5 × 10−7), whereas in JAK2V617F-positive cases rs9376092 associates with essential thrombocythemia (ET) rather than polycythemia vera (allelic χ2 P=7.3 × 10−7). Reduced MYB expression, previously linked to development of an ET-like disease in model systems, associates with rs9376092 in normal myeloid cells. These findings demonstrate that multiple germline variants predispose to MPN and link constitutional differences in MYB expression to disease phenotype
Long-term evidence for ecological intensification as a pathway to sustainable agriculture
Ecological intensification (EI) could help return agriculture into a ‘safe operating space’ for humanity. Using a novel application of meta-analysis to data from 30 long-term experiments from Europe and Africa (comprising 25,565 yield records), we investigated how field-scale EI practices interact with each other, and with N fertilizer and tillage, in their effects on long-term crop yields. Here we confirmed that EI practices (specifically, increasing crop diversity and adding fertility crops and organic matter) have generally positive effects on the yield of staple crops. However, we show that EI practices have a largely substitutive interaction with N fertilizer, so that EI practices substantially increase yield at low N fertilizer doses but have minimal or no effect on yield at high N fertilizer doses. EI practices had comparable effects across different tillage intensities, and reducing tillage did not strongly affect yields
Long-term evidence for ecological intensification as a pathway to sustainable agriculture
Ecological intensification (EI) could help return agriculture into a 'safe operating space' for humanity. Using a novel application of meta-analysis to data from 30 long-term experiments from Europe and Africa (comprising 25,565 yield records), we investigated how field-scale EI practices interact with each other, and with N fertilizer and tillage, in their effects on long-term crop yields. Here we confirmed that EI practices (specifically, increasing crop diversity and adding fertility crops and organic matter) have generally positive effects on the yield of staple crops. However, we show that EI practices have a largely substitutive interaction with N fertilizer, so that EI practices substantially increase yield at low N fertilizer doses but have minimal or no effect on yield at high N fertilizer doses. EI practices had comparable effects across different tillage intensities, and reducing tillage did not strongly affect yields.Intensifying food production sustainably is critical given growing demand and agriculture's environmental footprint. This meta-analysis finds that practices such as adding organic matter and increasing crop diversity can partly substitute for nitrogen fertilizer to sustain or increase yields
Wind redistribution of snow impacts the Ka- and Ku-band radar signatures of Arctic sea ice
Wind-driven redistribution of snow on sea ice alters its topography and microstructure, yet the impact of these processes on radar signatures is poorly understood. Here, we examine the effects of snow redistribution over Arctic sea ice on radar waveforms and backscatter signatures obtained from a surface-based, fully polarimetric Ka- and Ku-band radar at incidence angles between 0∘ (nadir) and 50∘. Two wind events in November 2019 during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition are evaluated. During both events, changes in Ka- and Ku-band radar waveforms and backscatter coefficients at nadir are observed, coincident with surface topography changes measured by a terrestrial laser scanner. At both frequencies, redistribution caused snow densification at the surface and the uppermost layers, increasing the scattering at the air–snow interface at nadir and its prevalence as the dominant radar scattering surface. The waveform data also detected the presence of previous air–snow interfaces, buried beneath newly deposited snow. The additional scattering from previous air–snow interfaces could therefore affect the range retrieved from Ka- and Ku-band satellite altimeters. With increasing incidence angles, the relative scattering contribution of the air–snow interface decreases, and the snow–sea ice interface scattering increases. Relative to pre-wind event conditions, azimuthally averaged backscatter at nadir during the wind events increases by up to 8 dB (Ka-band) and 5 dB (Ku-band). Results show substantial backscatter variability within the scan area at all incidence angles and polarizations, in response to increasing wind speed and changes in wind direction. Our results show that snow redistribution and wind compaction need to be accounted for to interpret airborne and satellite radar measurements of snow-covered sea ice
Wind redistribution of snow impacts the Ka- and Ku-band radar signatures of Arctic sea ice
Wind-driven redistribution of snow on sea ice alters its
topography and microstructure, yet the impact of these processes on radar
signatures is poorly understood. Here, we examine the effects of snow
redistribution over Arctic sea ice on radar waveforms and backscatter
signatures obtained from a surface-based, fully polarimetric Ka- and Ku-band
radar at incidence angles between 0∘ (nadir) and 50∘.
Two wind events in November 2019 during the Multidisciplinary drifting Observatory for
the Study of Arctic Climate (MOSAiC) expedition are evaluated. During both events, changes in Ka- and
Ku-band radar waveforms and backscatter coefficients at nadir are observed,
coincident with surface topography changes measured by a terrestrial laser
scanner. At both frequencies, redistribution caused snow densification at
the surface and the uppermost layers, increasing the scattering at the
air–snow interface at nadir and its prevalence as the dominant radar scattering surface. The waveform data also detected the presence of previous
air–snow interfaces, buried beneath newly deposited snow. The additional
scattering from previous air–snow interfaces could therefore affect the
range retrieved from Ka- and Ku-band satellite altimeters. With increasing
incidence angles, the relative scattering contribution of the air–snow
interface decreases, and the snow–sea ice interface scattering increases.
Relative to pre-wind event conditions, azimuthally averaged backscatter at
nadir during the wind events increases by up to 8 dB (Ka-band) and 5 dB (Ku-band). Results show substantial backscatter variability within the scan
area at all incidence angles and polarizations, in response to increasing
wind speed and changes in wind direction. Our results show that snow
redistribution and wind compaction need to be accounted for to interpret
airborne and satellite radar measurements of snow-covered sea ice
Position Exchange Theory: A socio-material basis for discursive and psychological positioning
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