74 research outputs found
Residual Nitrate and Mineralizable Soil Nitrogen in Relation to Nitrogen Uptake by Irrigated Sugarbeets
Previously reported studies on N fertilization of sugarbeets
(Beta vulgaris L.) in southern Idaho revealed considerable
variation among sites in amounts of residual
soil NO? and N mineralized during short-term laboratory
incubations. Consequently, the amount of N fertilizer
needed to achieve near-maximum yields of sucrose differed
markedly. The purpose of this study was to determine
the feasibility of estimating amounts of N mineralized
in the root zone during the season, taking into
account site variations in temperature and soil water
regimes. Residual soil NO?--N and mineralizable N to
approximate rooting depth were estimated for 21 field
sites in 1971 and six sites in 1972. The relative contributions
of these two N sources to total N uptake by the
crop, in the absence of applied fertilizer N, were then
assessed. Estimates of N mineralized in the upper 45-
cm soil layer for each successive month, ?N, over a 6-
month period were derived using the expression, ?N/
?t kWN (k = fraction of N mineralized during each
month, ?t, adjusted for average air temperature; and W
the estimated soil water content expressed as a fraction
of the available water storage capacity). Resulting
estimates of the fraction of potentially mineralizable N
converted to (NO?- + NH?+)-N between 1 April and
30 September ranged from 0.15 to 0.22 (mean ± S.D. =
0.18 ± 0.02) in 1971 and 1972. On the average, mature
sugarbeets recovered about 73% of the estimated N mineralized
(6 months) plus residual NO?--N. The relative
contributions of these two sources of soil derived N, respectively,
were approximately 66 and 75%, as estimated
from multiple regression analyses
Residual Nitrate and Mineralizable Soil Nitrogen in Relation to Nitrogen Uptake by Irrigated Sugarbeets
Previously reported studies on N fertilization of sugarbeets
(Beta vulgaris L.) in southern Idaho revealed considerable
variation among sites in amounts of residual
soil NO? and N mineralized during short-term laboratory
incubations. Consequently, the amount of N fertilizer
needed to achieve near-maximum yields of sucrose differed
markedly. The purpose of this study was to determine
the feasibility of estimating amounts of N mineralized
in the root zone during the season, taking into
account site variations in temperature and soil water
regimes. Residual soil NO?--N and mineralizable N to
approximate rooting depth were estimated for 21 field
sites in 1971 and six sites in 1972. The relative contributions
of these two N sources to total N uptake by the
crop, in the absence of applied fertilizer N, were then
assessed. Estimates of N mineralized in the upper 45-
cm soil layer for each successive month, ?N, over a 6-
month period were derived using the expression, ?N/
?t kWN (k = fraction of N mineralized during each
month, ?t, adjusted for average air temperature; and W
the estimated soil water content expressed as a fraction
of the available water storage capacity). Resulting
estimates of the fraction of potentially mineralizable N
converted to (NO?- + NH?+)-N between 1 April and
30 September ranged from 0.15 to 0.22 (mean ± S.D. =
0.18 ± 0.02) in 1971 and 1972. On the average, mature
sugarbeets recovered about 73% of the estimated N mineralized
(6 months) plus residual NO?--N. The relative
contributions of these two sources of soil derived N, respectively,
were approximately 66 and 75%, as estimated
from multiple regression analyses
Deconfining Phase Transition as a Matrix Model of Renormalized Polyakov Loops
We discuss how to extract renormalized from bare Polyakov loops in SU(N)
lattice gauge theories at nonzero temperature in four spacetime dimensions.
Single loops in an irreducible representation are multiplicatively renormalized
without mixing, through a renormalization constant which depends upon both
representation and temperature. The values of renormalized loops in the four
lowest representations of SU(3) were measured numerically on small, coarse
lattices. We find that in magnitude, condensates for the sextet and octet loops
are approximately the square of the triplet loop. This agrees with a large
expansion, where factorization implies that the expectation values of loops in
adjoint and higher representations are just powers of fundamental and
anti-fundamental loops. For three colors, numerically the corrections to the
large relations are greatest for the sextet loop, ; these
represent corrections of for N=3. The values of the renormalized
triplet loop can be described by an SU(3) matrix model, with an effective
action dominated by the triplet loop. In several ways, the deconfining phase
transition for N=3 appears to be like that in the matrix model of
Gross and Witten.Comment: 24 pages, 7 figures; v2, 27 pages, 12 figures, extended discussion
for clarity, results unchange
Genome-wide association study of kidney function decline in individuals of European descent.
Genome-wide association studies (GWASs) have identified multiple loci associated with cross-sectional eGFR, but a systematic genetic analysis of kidney function decline over time is missing. Here we conducted a GWAS meta-analysis among 63,558 participants of European descent, initially from 16 cohorts with serial kidney function measurements within the CKDGen Consortium, followed by independent replication among additional participants from 13 cohorts. In stage 1 GWAS meta-analysis, single-nucleotide polymorphisms (SNPs) at MEOX2, GALNT11, IL1RAP, NPPA, HPCAL1, and CDH23 showed the strongest associations for at least one trait, in addition to the known UMOD locus, which showed genome-wide significance with an annual change in eGFR. In stage 2 meta-analysis, the significant association at UMOD was replicated. Associations at GALNT11 with Rapid Decline (annual eGFR decline of 3 ml/min per 1.73 m(2) or more), and CDH23 with eGFR change among those with CKD showed significant suggestive evidence of replication. Combined stage 1 and 2 meta-analyses showed significance for UMOD, GALNT11, and CDH23. Morpholino knockdowns of galnt11 and cdh23 in zebrafish embryos each had signs of severe edema 72 h after gentamicin treatment compared with controls, but no gross morphological renal abnormalities before gentamicin administration. Thus, our results suggest a role in the deterioration of kidney function for the loci GALNT11 and CDH23, and show that the UMOD locus is significantly associated with kidney function decline.Kidney International advance online publication, 10 December 2014; doi:10.1038/ki.2014.361
Corrigendum: 1000 Genomes-based meta-analysis identifies 10 novel loci for kidney function.
This corrects the article DOI: 10.1038/srep45040
1000 Genomes-based metaanalysis identifies 10 novel loci for kidney function
HapMap imputed genome-wide association studies (GWAS) have revealed >50 loci at which common variants with minor allele frequency >5% are associated with kidney function. GWAS using more complete reference sets for imputation, such as those from The 1000 Genomes project, promise to identify novel loci that have been missed by previous efforts. To investigate the value of such a more complete variant catalog, we conducted a GWAS meta-Analysis of kidney function based on the estimated glomerular filtration rate (EGFR) in 110,517 European ancestry participants using 1000 Genomes imputed data. We identified 10 novel loci with p-value < 5 × 10-8 previously missed by HapMap-based GWAS. Six of these loci (HOXD8, ARL15, PIK3R1, EYA4, ASTN2, and EPB41L3) are tagged by common SNPs unique to the 1000 Genomes reference panel. Using pathway analysis, we identified 39 significant (FDR < 0.05) genes and 127 significantly (FDR < 0.05) enriched gene sets, wh
Genetic insights into biological mechanisms governing human ovarian ageing
Reproductive longevity is essential for fertility and influences healthy ageing in women, but insights into its underlying biological mechanisms and treatments to preserve it are limited. Here we identify 290 genetic determinants of ovarian ageing, assessed using normal variation in age at natural menopause in approximately 200,000 women of European ancestry. These common alleles were associated with clinical extremes of age at natural menopause; women in the top 1% of genetic susceptibility have an equivalent risk of premature ovarian insufficiency to those carrying monogenic FMR1 premutations. The identified loci implicate a broad range of DNA damage response (DDR) processes and include loss-of-function variants in key DDR-associated genes. Integration with experimental models demonstrates that these DDR processes act across the lifecourse to shape the ovarian reserve and its rate of depletion. Furthermore, we demonstrate that experimental manipulation of DDR pathways highlighted by human genetics increases fertility and extends reproductive life in mice. Causal inference analyses using the identified genetic variants indicate that extending reproductive life in women improves bone health and reduces risk of type 2 diabetes, but increases the risk of hormone-sensitive cancers. These findings provide insight into the mechanisms that govern ovarian ageing, when they act, and how they might be targeted by therapeutic approaches to extend fertility and prevent disease
Genome-wide association meta-analyses and fine-mapping elucidate pathways influencing albuminuria
Increased levels of the urinary albumin-to-creatinine ratio (UACR) are associated with higher risk of kidney disease progression and cardiovascular events, but underlying mechanisms are incompletely understood. Here, we conduct trans-ethnic (n = 564,257) and European-ancestry specific meta-analyses of genome-wide association studies of UACR, including ancestry- and diabetes-specific analyses, and identify 68 UACR-associated loci. Genetic correlation analyses and risk score associations in an independent electronic medical records database (n = 192,868) reveal connections with proteinuria, hyperlipidemia, gout, and hypertension. Fine-mapping and trans-Omics analyses with gene expression in 47 tissues and plasma protein levels implicate genes potentially operating through differential expression in kidney (including TGFB1, MUC1, PRKCI, and OAF), and allow coupling of UACR associations to altered plasma OAF concentrations. Knockdown of OAF and PRKCI orthologs in Drosophila nephrocytes reduces albumin endocytosis. Silencing fly PRKCI further impairs slit diaphragm formation. These results generate a priority list of genes and pathways for translational research to reduce albuminuria
Repositioning of the global epicentre of non-optimal cholesterol
High blood cholesterol is typically considered a feature of wealthy western countries1,2. However, dietary and behavioural determinants of blood cholesterol are changing rapidly throughout the world3 and countries are using lipid-lowering medications at varying rates. These changes can have distinct effects on the levels of high-density lipoprotein (HDL) cholesterol and non-HDL cholesterol, which have different effects on human health4,5. However, the trends of HDL and non-HDL cholesterol levels over time have not been previously reported in a global analysis. Here we pooled 1,127 population-based studies that measured blood lipids in 102.6 million individuals aged 18 years and older to estimate trends from 1980 to 2018 in mean total, non-HDL and HDL cholesterol levels for 200 countries. Globally, there was little change in total or non-HDL cholesterol from 1980 to 2018. This was a net effect of increases in low- and middle-income countries, especially in east and southeast Asia, and decreases in high-income western countries, especially those in northwestern Europe, and in central and eastern Europe. As a result, countries with the highest level of non-HDL cholesterol—which is a marker of cardiovascular risk—changed from those in western Europe such as Belgium, Finland, Greenland, Iceland, Norway, Sweden, Switzerland and Malta in 1980 to those in Asia and the Pacific, such as Tokelau, Malaysia, The Philippines and Thailand. In 2017, high non-HDL cholesterol was responsible for an estimated 3.9 million (95% credible interval 3.7 million–4.2 million) worldwide deaths, half of which occurred in east, southeast and south Asia. The global repositioning of lipid-related risk, with non-optimal cholesterol shifting from a distinct feature of high-income countries in northwestern Europe, north America and Australasia to one that affects countries in east and southeast Asia and Oceania should motivate the use of population-based policies and personal interventions to improve nutrition and enhance access to treatment throughout the world.</p
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