Variation In Estimates Research Articles

Assessment of Genetic Divergence in Rice (Oryza sativa L.) Germplasm Using D2 Analysis

The present investigation was conducted with 41 genotypes of Rice during Kharif 2023 under Randomized Block Design (RBD) with three replications. Data were recorded for thirteen quantitative characters to obtain estimates of variability, heritability, genetic advance and genetic divergence. Significant differences were observed among the genotypes for all the characters studied. This study concluded, the highest grain yield was observed in VASUMATHI 38.9 followed by DHAN-69 34.33 based on mean performance at Prayagraj region. A higher magnitude of PCV as well as GCV coefficient of variation was noted for the number of total tillers per plant (22.05) and (21.20). Whereas the lowest PCV and GCV coefficient of variation was recorded for Days to maturity (7.40 and 6.80). High estimates of heritability (above 60%) in broad sense were recorded for all the thirteen characters under study, which ranged from 92.45% number of total tillers per plant to 61.55 harvest index. along with high genetic advance for number of spikelets per panicle (54.38), plant height (cm) (27.95), days to 50% flowering (22.93), and days to maturity (17.72). Biological yield (g) (15.33), harvest index (%) (11.06) and flag leaf length (cm) (10.05) D2 analysis distributed the 41 genotypes into six clusters. The largest cluster was cluster I with 36 genotypes followed by cluster II, III, IV, V, VI with 1 genotype each. Highest contribution in manifestation of genetic divergence was exhibited by grain yield per plant (22.82) followed by biological yield (21.28) and test weight (12.56). Lowest intercluster distance was between cluster I and cluster IV which was (60.58). The intercluster distance was maximum between cluster IV and VI (247.17). Therefore, genotypes present in these clusters should be used for the future hybridization program. Highlights: Germplasms were grouped into 6 clusters. Cluster IV and VI were the most divergent clusters

Examining Risk Assessment Implications of Genetic and Dose-Dependent Dynamics of Lead Exposure in Breastfeeding Using the Collaborative Cross Mouse Population.

Breastfeeding offers well-documented advantages but may inadvertently introduce lead (Pb) exposure to infants. Scarce data exists on the risks of Pb exposure for breastfed infants, and strategies for risk mitigation are needed, particularly considering the heightened susceptibility of children to adverse effects from Pb exposure. To investigate the potential influence of breastfeeding on blood Pb levels (BLL) in offspring, population variation in BLL between non-parous and parous mouse dams was quantified, as well as in dams exposed to low- and high-dose while breastfeeding, and their offspring. Female mice from 14 distinct Collaborative Cross (CC) mouse strains were mated with sires from different CC strains to produce 14 F1 hybrids. Subsequently, dams were administered either low- (100 ppm) or high- (1000 ppm) dose Pb through ad libitum access drinking water starting the day of delivery for a duration of 4 weeks, leading to the subsequent exposure of the offspring via lactation. Genetic background emerged as a predominant factor contributing to variation, with substantial inter-strain variability observed in both CC dams and F1 hybrids exposed to low- and high-doses of Pb. Crucially, the degree of variation in BLL among CC dams exceeded the default variability estimate (geometric standard deviation = 1.6) utilized in regulatory standard settings. These findings underscore the importance of integrating population variability in risk assessment. Ultimately, this study provides critical insights to guide public health decision-making processes concerning Pb exposure through breastfeeding and its potential implications for infants' health.

Accurate estimation of interobserver variability in echocardiography segmentation measured from 35 experts and impact on derived clinical metrics

Abstract Introduction The delineation of cardiac structures is crucial to the analysis of echocardiography images and a prerequisite for the calculation of clinical metrics derived from heart chamber areas and volumes. Nevertheless, significant interobserver variability exists due to anatomical variability and echocardiography image quality, leading to discrepancies in endocardial border tracing [1]. Estimations of interobserver variability reported in the literature are based on measurements from a reduced number of annotations per sample [2]. Purpose This work aims to elaborate on previous interobserver variability studies presented in the literature to improve the accuracy and robustness of the estimations by considering (1) a large cohort of annotators and (2) a controlled environment, where the interobserver variability is isolated from other sources of variability, such as image acquisition, cardiac cycle selection or labelling method. Methods A group of 35 experienced sonographers independently delineated the heart chambers at end-systole (ES) and end-diastole (ED) in apical 4-chamber (A4C) and 2-chamber (A2C) views from a cohort of 10 patients (median age 72, IQR: 52-77; predominantly male, 70%), resulting in a total of 120 corresponding annotations per sonographer. The ES and ED frames were preselected by a clinical committee for each sequence to remove this source of variability. Segmentations of each sonographer were used to derive the area of the heart chambers, along with several clinical metrics routinely used to assess cardiac morphology and function. Variability was quantified via relative standard deviation (RSD) and intraclass correlation coefficient (ICC). Results The analysis confirmed a large interobserver variability, with a global RSD of 15.4±5.2% and ICC of 0.89 in area (Figure 1). Variability was significantly higher at ES phase (p<0.001) and in A2C view (p=0.02). No significant differences were found across heart chambers. The annotation variability directly affected the calculation of clinical metrics, leading to particularly large RSD values for those metrics derived from multiple annotations (Figure 2). The variability of left ventricular ejection fraction (LVEF) was 16.0±3.4%, in line with the literature [3]. However, the LVEF ICC was highly compromised (0.187), suggesting that the interobserver variability is larger than the variability of the metric itself. This raises concerns about the use of LVEF derived from manual segmentation as a robust diagnostic reference [4]. These findings argue the need for enhanced standardization protocols and a swift towards automated annotation that mitigate this variability, as evidenced in the EchoNet trial [5]. Conclusion This study accurately evaluates the echocardiography segmentation interobserver variability and its impact on clinical metrics. The findings confirm a large variability and highlight the need to mitigate it, ultimately improving diagnostic assessment.

Retrospective Analyses of Stability and Variability in Relative Age Effects of Handball Talents Over Seventeen Years

In the last thirty years research on relative age effects (RAEs) has exploded in numbers. However, the stability and variability of these effects have hardly been investigated. The three aims of this retrospective study were first to investigate the stability and variability of RAEs over 17 years, second to compare these effects for young female and male athletes, and third to compare these effects between selected and non-selected athletes relative to variability estimates from 17 years prior to assess possible changes in athlete development trends. For this study, birth dates were provided for all participants of the talent selection camps by the German Handball Federation from 2008 to 2024. Results show that first while some variability was observed, the effects remained stable. Second, there are only small differences between sexes in general, although these increased with selection. And thirdly, that selections create stronger effects for male athletes, but not for female ones. Taken together, this study provides an interesting picture of the variability and stability of relative age effects over 17 years.

Risky actions: Why and how to estimate variability in motor performance.

We describe the difficulties of measuring variability in performance, a critical but largely ignored problem in studies of risk perception. The problem seems intractable if a large number of successful and unsuccessful trials are infeasible. We offer a solution based on estimates of task-specific variability pooled across the sample. Using a dataset of adult performance in throwing and walking tasks, we show that mischaracterizing the slope leads to unacceptably large errors in estimates of performance levels that undermine analyses of risk perception. We introduce a "pooled-slope" solution that approximates estimates of individual variability in performance and outperforms arbitrary assumptions about performance variability within and across tasks. We discuss the advantages of objectively measuring performance based on the rate of successful attempts-modeled via psychometric functions-for improving comparisons of risk across participants, tasks, and studies.

An improved ratio-type estimator of population coefficient of variation

This study discusses the challenges associated with estimating the population coefficient of variation using sampling survey techniques. Yunusa et al. (2021) motivate this study. We further improve these estimators to estimate this study's unknown population coefficient of variation. Using two populations as examples, empirical results indicate that the proposed estimator provides more accurate estimates of population variability since it is more efficient. Further research and validation are recommended to establish the robustness and generalizability of the proposed estimator.

Model estimates of interannual variability of the Lake Ladoga ecosystem characteristics in the period from 1980 to 2020

Model estimates of interannual variability of the Lake Ladoga ecosystem characteristics in the period from 1980 to 2020

Long-Term Hydrologic Variability in the Instrumental Record of California Climate

This study characterizes the instrumental record of California climate for the last 170 years. Our goal is to look for hydrologic variability at decadal and longer time scales that would be consistent with paleoclimate estimates of hydrologic variability in California for the last 3000 years. Our study focuses on meteorological summaries of annual precipitation and temperature. The precipitation records go back as far as 1850; the temperature records go back as far as 1880. California hydrologic records show strong variability at the interannual level due to ENSO forcing. They also all show a strong decadal (~14 yr) cyclicity and evidence for multi-decadal to centennial variability that is consistent with California paleoclimate studies. California temperature records show a long-term warming of 5 °F−6 °F (2.8 °C−3.4 °C) associated with global warming, but there is no evidence for a similar long-term trend in hydrologic variability. Long-term Pacific Ocean variability adjacent to central and northern California, Pacific Decadal Oscillation (PDO) and North Pacific Gyre Oscillation (NPGO), show a similar decadal to centennial pattern of variability that we associate with our long-term hydrologic variability. The positive phase of the NPGO and the negative phase of the PDO are associated with the decadal scale (~14 yr) dry cycles in California for the last 70 years.

Time to glaucoma progression detection by optical coherence tomography and visual field in glaucoma individuals of African descent

To examine the time to glaucoma progression detection by retinal nerve fiber layer thickness (RNFLT) and visual field (VF) among individuals of African descent (AD). Retrospective cohort study. This multicenter study included eyes with glaucoma from individuals of AD from the Diagnostic Innovations in Glaucoma Study and the African Descent and Glaucoma Evaluation Study with ≥2 years/5 visits of optic nerve head RNFLT and 24-2 VF examinations. Rates of VF mean deviation (MD) and RNFLT worsening were analyzed using linear mixed-effects models, and longitudinal data were simulated using the variability estimates. The simulated time to detect trend-based glaucoma progression was assessed with assumed rates of VF MD and RNFLT change derived from the cohort (25th, 50th, and 75th percentile [as p25, median, and p75] slopes and mean slopes). Severity-stratified analyses were also performed. We included 184 eyes from 128 subjects of AD (mean baseline age 63.4 years; VF MD -4.2 dB; RNFLT 80.2 µm). The p25, median, mean, and p75 rates of change were -0.43, -1.01, -1.15, and -1.64 µm per year for RNFLT, and 0.00, -0.21, -0.30, and -0.51 dB per year for VF MD, respectively. Compared with VF MD, RNFLT showed an overall shorter mean time to progression detection (time difference 0.4-1.7 years), with the mean rates showing the largest difference (RNFLT 5.2 years vs VF MD 6.9 years). Similarly, we found an overall shorter time to detect RNFLT progression, compared with that of VF MD progression, in eyes with mild glaucoma (≥1 year earlier) and in eyes with moderate to advanced glaucoma (∼0.5 year earlier). Computer simulation showed a potentially shorter time to detect RNFLT progression than VF MD progression in eyes from individuals of AD. Our findings support the importance of using RNFLT to detect progressive glaucoma in individuals of AD.

Genetic improvement in Colombian cattle, a reality or an intention? A review

Background: Genetic improvement programs in domestic species require a set of steps involving the definition of breeding objectives, information systems, variance component estimation, genetic evaluations, selection indexes, and the estimation of genetic progress and variability. Objective: To identify strengths and weaknesses in the design and implementation of genetic improvement programs in Colombian cattle through scientific and academic contributions derived from research. Conclusion: The greatest challenges in the design and implementation of genetic improvement programs in Colombian cattle are currently related to the absence of consensus breeding objectives among farmers and associations. Additionally, there is a need in the short term to improve both the quality and quantity of information available in databases. Finally, conducting economic analyses that consider genetic parameters is essential for optimizing the response to genetic selection, considering the different productive systems and environmental conditions that Colombia offers.

Estimation of genetic variability, heritability, and genetic advance for drought-tolerant traits in an F2 mapping population of rice

Estimation of genetic variability, heritability, and genetic advance for drought-tolerant traits in an F2 mapping population of rice

State of knowledge for thermohaline conditions on the shelf of West Kamchatka

All available data on water temperature and salinity for the shelf of West Kamchatka are analyzed and all scientific publications and the most important unpublished thesises concerning this area are summarized. Current ideas about the water masses distribution and seasonal and long-term variability of water temperature and salinity on the shelf are discussed. There is noted that the existing estimates of seasonal and long-term variability of water temperature require significant additions for recent times (last 20 years) and certain spatial areas. Insufficient understanding is revealed for spatial-temporal dynamics of salinity in the mixing zone between the river and sea waters that requires special research.

Unravelling the Genetic Complexity: Enhancing MYMV Resistance in Blackgram [Vigna mungo (L.) Hepper] Through Trait-based Selection

Background: Limited genetic diversity in blackgram, stemming from its common ancestry with greengram, presents challenges in combating Mungbean Yellow Mosaic Virus (MYMV), leading to yield stagnation. To address this, genetic screening and selection of segregating generations in F2 are essential for refining resistance traits with enhancing productivity. Methods: A two-season experiment was conducted in Panpoli, Tamil Nadu, during the Kharif 2021 and Kharif 2022 in a randomized block design using, F2 seeds from specific crosses (MDU 1 × Mash 114 and ADT 3 × PU 31), along with F1 and parent plants. MYMV disease scores were recorded using the infector row method for all the genotypes studied. Result: The study unveiled a complex genetic basis of MYMV resistance in blackgram, characterized by di-genic dominant genes displaying duplicative dominance type of epistatic interaction. This complexity underscores the insufficiency of simple selection methods. Estimates of genetic variability for “number of pods per plant” exhibited high genetic advance and moderate heritability, indicating control by additive genes. Positive correlations were observed between plant height, number of clusters per plant and number of pods per plant with yield. Path analysis revealed that traits like number of seeds per pod, 100 seed weight and number of pods per plant directly and positively influenced yield, which exhibit minimal influence from MYMV. These traits offer crucial selection criteria for enhancing MYMV resistance in blackgram.

Estimates of genetic variability and interplay of germination and seedling traits conferring salinity tolerance in rice (Oryza sativa L.)

This study estimates genetic variability and correlations among germination and seedling traits conferring salinity tolerance in rice accessions. Five rice accessions were screened under salinity levels of 0, 50, 100, and 200 mM NaCl in a controlled laboratory setting. Traits such as germination energy, capacity, shoot and root length, and biomass were measured. Data were analyzed for variance and correlations to assess variability and trait relationships. Significant genetic variability was found among accessions for all traits. Germination energy showed the highest coefficient of variation (CV) at 22.29% under control conditions, while fresh shoot weight had the highest CV (34.35%) under 200 mM salinity. Accessions ACC2 and ACC5 consistently demonstrated higher performance in germination energy (23.33 to 53.33% and 10.00 to 41.67%), germination capacity (40.00 to 60.00% and 28.33 to 46.67%), and shoot length (0.67 to 2.97 cm and 0.40 to 3.93 cm) under various salinity stress levels. ACC1, ACC3, and ACC4 showed more variability but maintained some consistency in specific traits, with ACC4 generally showing lower performance across most traits. Genetic parameter estimates indicated high heritability (˃60%) for all traits, with the highest in germination capacity (96.88%). High genetic advance (GAM) was observed for all traits (˃20%), with germination energy showing the highest (107.00%). Traits with high heritability and genetic advance, such as germination energy, germination capacity, and root length, suggest strong genetic control and potential for improvement through selective breeding. Significant correlations were found between germination energy and capacity (r= 0.89 to 0.96) and between shoot length and leaf length (r= 0.92) under stress conditions. Stress tolerance indices identified accessions ACC2 and ACC5 as the most tolerant, with ACC1 showing consistent performance across traits. This study underscores the importance of identifying resilient traits and accessions to enhance salinity tolerance in rice, contributing to improved productivity in saline-affected regions.

South Atlantic meridional overturning circulation and its respective heat and freshwater transports from sustained observations near 34.5°S

The Atlantic Meridional Overturning Circulation (AMOC) drives northward Meridional Heat Transport (MHT) and affects climate and weather patterns, regional sea levels, and ecosystems. This study uses a methodology recently applied in 22.5°S to estimate the strength and structure of the AMOC, MHT and freshwater (FWT) transports at 34.5°S since 2005. For this, temperature and salinity profiles from sustained observations were used in conjunction with satellite and reanalysis data under two mapping methodologies: (i) an optimized mapping and (ii) a two-layer feed-forward neural network approach. There is strong agreement between both methods for AMOC, MHT and FWT estimates, thus showing the mapping methodologies are robust. In addition, the AMOC variability estimate is significantly correlated with the monthly SAMBA array data (correlation of 0.41). The mean AMOC transport of 17.0 ± 1.6 Sv, a MHT of 0.6 ± 0.1 PW, and a FWT of -0.02 ± 0.01 Sv are estimated between January 2005 and May 2023 at 34.5°S. The MHT and FWT are analyzed in terms of their horizontal (Hhor and Fhor) and overturning contributions (Hov and Fov), and vertical structures. The MHT is dominated by the overturning contribution (correlation of 0.92), while the FWT is controlled by the overturning contribution driven by the wind via Ekman transport at seasonal timescale, and by horizontal contribution at longer timescales. Both horizontal heat (Hhor) and freshwater (Fhor) components are mostly confined to the upper 500 m, with the geostrophic Fov and Fhor offsetting each other between 50 m and 500 m, and the Ekman Fov in the upper 50 m determining the negative FWT. Finally, the estimated mean Fov of -0.15 Sv agrees with previous estimates that the AMOC exports freshwater in the South Atlantic, and suggests that the AMOC is unstable. Although a long-term trend in the Fov was not detected in the past 20 years, there is a salinification trend (0.05 ± 0.01 PSU/decade) in the upper 300 m near 34.5°S since 2005.

Number of macula optical coherence tomography scans needed to detect glaucoma progression

BackgroundTo evaluate the impact of testing frequency on the time required to detect statistically significant glaucoma progression for ganglion cell complex (GCC) with optical coherence tomography (OCT).Materials and methodsFrom multicentre...

A global Data Assimilation of Moisture Patterns from 21 000–0 BP (DAMP-21ka) using lake level proxy records

Abstract. Global hydroclimate significantly differed from modern climate during the mid-Holocene (6 ka) and Last Glacial Maximum (21 ka). Consequently, both periods have been described as either a partial or reverse analogue for current climate change. To reconstruct past hydroclimate, an offline paleoclimate data assimilation methodology is applied to a dataset of 216 lake status records which provide relative estimates of water level change. The proxy observations are integrated with the climate dynamics of two transient simulations (TraCE-21ka and HadCM3) using a multivariate proxy system model (PSM) which estimates relative lake status from available climate simulation variables. The resulting DAMP-21ka (Data Assimilation of Moisture Patterns 21 000–0 BP) reanalysis reconstructs annual lake status and precipitation values at 500-year resolution and represents the first application of the methodology to global hydroclimate on timescales spanning the Holocene and longer. Validation using Pearson's correlation coefficients indicates that the reconstruction (0.24) is more skillful, on average, than model simulations (0.09), particularly in portions of North America and east Africa, where data density is high and proxy–model disagreement is prominent during the Holocene. Results of the PSM and assimilation are used to evaluate climatic controls on lake status, spatiotemporal patterns of moisture variability, and proxy–model disagreement. During the mid-Holocene, wetter conditions are reconstructed for northern and eastern Africa, Asia, and southern Australia, but in contrast to the model prior, negative anomalies are observed in North America, resulting in drier-than-modern conditions throughout the Northern Hemisphere midlatitudes. Proxy–model disagreement in western North America may reflect a bias in model simulations to stronger sea level pressure gradients in the North Pacific during the mid-Holocene. The data assimilation framework is able to reconcile these differences by integrating the constraints of proxy observations with the dynamics of the model prior to produce a more robust estimation of hydroclimate variability during the past 21 000 years.

Estimation of the spatial variability of the New England Mud Patch geoacoustic properties using a distributed array of hydrophones and deep learning

This article presents a spatial environmental inversion scheme using broadband impulse signals with deep learning (DL) to model a single spatially-varying sediment layer over a fixed basement. The method is applied to data from the Seabed Characterization Experiment 2022 (SBCEX22) in the New England Mud-Patch (NEMP). Signal Underwater Sound (SUS) explosive charges generated impulsive signals recorded by a distributed array of bottom-moored hydrophones. The inversion scheme is first validated on a range-dependent synthetic test set simulating SBCEX22 conditions, then applied to experimental data to predict the lateral spatial structure of sediment sound speed and its ratio with the interfacial water sound speed. Traditional geoacoustic inversion requires significant computational resources. Here, a neural network enables rapid single-signal inversion, allowing the processing of 1836 signals along 722 tracks. The method is applied to both synthetic and experimental data. Results from experimental data suggest an increase in both absolute compressional sound speed and sound speed ratio from southwest to northeast in the NEMP, consistent with published coring surveys and geoacoustic inversion results. This approach demonstrates the potential of DL for efficient spatial geoacoustic inversion in shallow water environments.

Locally Defined Seasonal Rainfall Characteristics within the Horn of Africa Drylands from Rain Gauge Observations

Abstract Seasonal rainfall is critical to lives and livelihoods within the Horn of Africa drylands (HAD), but it is highly variable in space and time. The main HAD rainfall seasons are typically defined as March–May (MAM) and October–December (OND). However, these 3-month periods are only generalized definitions of seasonality across the HAD, and local experience of rainfall may depart from these substantially. Here, we use daily rain gauge data with a duration of at least 10 years from 69 stations across the drylands of Kenya, Somalia, and Ethiopia to locally delineate key rainfall seasons. By calculating local seasonal rainfall timings, totals, and extremes, we obtain more accurate estimates of the spatial variability in rainfall delivery across the HAD, as well as climatological patterns. Results show high spatial variability in season onset, cessation, and length across the region, indicating that a homogenous classification of rainfall seasons across the HAD (e.g., MAM and OND) is inadequate for representing local rainfall characteristics. Our results show that the “long rains” season is not significantly longer than the “short rains” season over the period of study. This could be related to the previously documented decline of the “long rains” seasonal totals over recent decades. Several rainfall metrics also vary spatially between seasons, and the rainfall on the most extreme days can accumulate to double the local mean seasonal total. The locally defined rainfall seasons better capture the bulk of the rainfall during the season, giving improved characterization of rainfall metrics, consistent with the aim of a better understanding of rainfall impacts on local communities.

Geomagnetic support for directional drilling

The high-tech directional drilling (DD) procedure for the development of hydrocarbon resources requires high precision positioning of the drill string. Such accuracy can be achieved by navigation based on the Earth’s magnetic field (EMF), which ensures hitting a given target with an error of 3 m at a distance of 15 km. However, the EMF is characterized by multi-scale variability both in space and time. Therefore, the full stack of DD geomagnetic support includes a detailed, real-time estimation of the EMF spatio-temporal variability in the deposit region and geomagnetic activity forecast. Particularly strict control of a drill string orientation is required when drilling in the Arctic region. The article is devoted to modern technologies for effective accounting of the features of the EMF space-time structure to ensure precise navigation of the drill string. The paper is based on the report delivered at the RAS Presidium meeting on 11 June 2024.