Low Coefficient Of Variation Research Articles

Estimation of Genetic Variability among Sorghum Genotypes for Different Morphological and Biochemical Traits

Fifty diverse genotypes of sorghum were evaluated for different metric traits to assess the genetic diversity during kharif 2018-19 for yield and its associating traits. Less difference between the estimates of GCV and PCV implying the minimal influence of environmental agencies and importantly, improvement through selection seems feasible. The coefficients of variation (GCV and PCV) for panicle length without peduncle, 100-grain weight, green fodder production, crude protein yield, and other variables were found to be high. Whereas, low genotypic coefficient of variation (GCV) and phenotypic coefficient of variation (PCV) were recorded for traits, crude protein, height up to flag leaf, plant height, stem diameter, stem diameter and time of panicle emergence. Leaf breadth, panicle length without peduncle, dry matter%, 100-grain weight, green and dry fodder yield, HCN and tannin content, crude protein all had high heritability and genetic advance.

Dynamics of ventilatory pattern variability and Cardioventilatory Coupling during systemic inflammation in rats.

Introduction: Biometrics of common physiologic signals can reflect health status. We have developed analytics to measure the predictability of ventilatory pattern variability (VPV, Nonlinear Complexity Index (NLCI) that quantifies the predictability of a continuous waveform associated with inhalation and exhalation) and the cardioventilatory coupling (CVC, the tendency of the last heartbeat in expiration to occur at preferred latency before the next inspiration). We hypothesized that measures of VPV and CVC are sensitive to the development of endotoxemia, which evoke neuroinflammation. Methods: We implanted Sprague Dawley male rats with BP transducers to monitor arterial blood pressure (BP) and recorded ventilatory waveforms and BP simultaneously using whole-body plethysmography in conjunction with BP transducer receivers. After baseline (BSLN) recordings, we injected lipopolysaccharide (LPS, n = 8) or phosphate buffered saline (PBS, n =3) intraperitoneally on 3 consecutive days. We recorded for 4-6h after the injection, chose 3 epochs from each hour and analyzed VPV and CVC as well as heart rate variability (HRV). Results: First, the responses to sepsis varied across rats, but within rats the repeated measures of NLCI, CVC, as well as respiratory frequency (fR), HR, BP and HRV had a low coefficient of variation, (<0.2) at each time point. Second, HR, fR, and NLCI increased from BSLN on Days 1-3; whereas CVC decreased on Days 2 and 3. In contrast, changes in BP and the relative low-(LF) and high-frequency (HF) of HRV were not significant. The coefficient of variation decreased from BSLN to Day 3, except for CVC. Interestingly, NLCI increased before fR in LPS-treated rats. Finally, we histologically confirmed lung injury, systemic inflammation via ELISA and the presence of the proinflammatory cytokine, IL-1β, with immunohistochemistry in the ponto-medullary respiratory nuclei. Discussion: Our findings support that NLCI reflects changes in the rat's health induced by systemic injection of LPS and reflected in increases in HR and fR. CVC decreased over the course to the experiment. We conclude that NLCI reflected the increase in predictability of the ventilatory waveform and (together with our previous work) may reflect action of inflammatory cytokines on the network generating respiration.

Effect of iodine concentration reduction by comparison of virtual monoenergetic image quality with dual-energy computed tomography

This study aimed to evaluate the image quality of virtual monoenergetic images (VMIs) with tube voltage modulation in pediatric abdominal computed tomography (CT) examination and to determine the effect of decreasing contrast agent concentration. Using a 1-year old pediatric phantom, five contrast agent concentration diluent tubes of 100%, 80%, 60%, 40%, and 20% of the same concentration as the average Hounsfield unit (HU) in the descending aorta were inserted, and the mixed image and VMIs (40, 60, and 80 keV) acquired using dual-energy CT were compared with single-energy CT (SECT) images. For quantitative evaluation, the HU and coefficient of variation (COV) of each image were compared and analyzed. The analysis revealed that the HU of the 40 keV VMIs, acquired with a tube voltage of 70 kV and 100% contrast agent concentration, was 61% higher than that of the SECT image. The results showed that SECT had the lowest COV among all contrast agent concentration and tube voltage combinations, while the 40 keV image acquired at 70 kV had the second-lowest COV value. The HU of the 40 keV image acquired at 70 kV at a contrast agent concentration of 100% was 9% higher than that of SECT at 80% concentration. This study confirms that 40 keV VMIs are more useful than SECT images for vascular diagnosis with contrast in pediatric abdominal CT examinations and that a 20% reduction in contrast agent concentration can reduce the risk of contrast agent concentration-induced nephrotoxicity in pediatric patients by increasing the subjective acceptability of image quality for diagnosis.

On the excessive use of coefficient of variation as a metric of quantitation quality in proteomics.

The coefficient of variation (CV) is often used in proteomics as a proxy to characterize the performance of a quantitation method and/or the related software. In this note, we question the excessive reliance on this metric in quantitative proteomics that may result in erroneous conclusions. We support this note using a ground-truth Human-Yeast-E. coli dataset demonstrating in a number of cases that erroneous data processing methods may lead to a low CV which has nothing to do with these methods' performances in quantitation.

Mirror, mirror on the wall… How tank material and the presence of “enrichments” affect competition and agonism in zebrafish (Danio rerio)

Despite generations of rearing in a laboratory environment, zebrafish (Danio rerio) retain innate preferences for environmental features that mimic their natural habitat (e.g. plants and gravel), but the effects of such preferred housing conditions on agonism are poorly understood. In this study, we worked with > 450 fish in 41 tanks to test two competing hypotheses about body size variation within shoals (a possible proxy for dominance hierarchy strength) and agonistic behaviour: A) the provision of preferred resources increases agonism (relative to levels in empty, barren tanks), possibly due to resource guarding behaviour, and B) barren housing conditions increase agonism (relative to levels in tanks containing preferred resources), possibly because subordinates are less able to hide from dominant fish. In Experiment 1, groups of 11–13 fish were housed for ∼ 1 year in 7 tanks in each of 3 treatments: empty lab-typical tanks, larger empty plastic tanks, and larger “well-resourced” plastic tanks containing preferred resources (gravel and artificial plants). Similarly, in Experiment 2, groups were housed in 5 tanks in each of 4 cross-factored treatments: empty glass aquaria, empty plastic tanks, well-resourced glass aquaria, and well-resourced plastic tanks. Live observations of agonistic behaviours and measures of body size variation (coefficient of variation for standard length and condition factor) were compared between treatments (using GLMs). In Experiment 1, empty lab-typical tanks exhibited significantly more agonistic behaviours than the other two treatment groups, which were not significantly different from each other. In Experiment 2, we found a significant interactive effect of housing treatment and tank material on agonism, where agonistic behaviours occurred most often in empty glass aquaria, possibly due to mirror-like reflections on glass walls. We therefore suggest that reflective surfaces in zebrafish housing systems should be minimized or visually disruptive resources like plants should be added to reduce agonism. Together both experiments also indicate that we need not be hesitant about adding preferred resources to captive zebrafishes’ housing environments, since they likely do not exacerbate agonism (and indeed may even reduce it). We also found two unexpected results: in Experiment 1, shoals exhibiting increased agonism had significantly lower coefficients of variation in standard length and in Experiment 2, fish in barren tanks grew significantly longer than those housed with preferred resources. Possible growth-related hypotheses are discussed and we suggest that high coefficients of variation in body size should not be used to infer high levels of agonism in zebrafish shoals.

Comprehensive evaluation and new recommendations in the use of Gafchromic EBT3 film.

Gafchromic film's unique properties of tissue-equivalence, dose-rate independence, and high spatial resolution make it an attractive choice for many dosimetric applications. However, complicated calibration processes and film handling limits its routine use. We evaluated the performance of Gafchromic EBT3 film after irradiation under a variety of measurement conditions to identify aspects of film handling and analysis for simplified but robust film dosimetry. The short- (from 5min to 100h) and long-term (months) film response was evaluated for clinically relevant doses of up to 50Gy for accuracy in dose determination and relative dose distributions. The dependence of film response on film-read delay, film batch, scanner type, and beam energy was determined. Scanning the film within a 4-h window and using a standard 24-h calibration curve introduced a maximum error of 2% over a dose range of 1-40Gy, with lower doses showing higher uncertainty in dose determination. Relative dose measurements demonstrated <1mm difference in electron beam parameters such as depth of 50% of the maximum dose value (R50 ), independent of when the film was scanned after irradiation or the type of calibration curve used (batch-specific or time-specific calibration curve) if the same default scanner was used. Analysis of films exposed over a 5-year period showed that using the red channel led to the lowest variation in the measured net optical density values for different film batches, with doses >10Gy having the lowest coefficient of variation (<1.7%). Using scanners of similar design produced netOD values within 3% after exposure to doses of 1-40Gy. This is the first comprehensive evaluation of the temporal and batch dependence of Gafchromic EBT3 film evaluated on consolidated data over 8years. The relative dosimetric measurements were insensitive to the type of calibration applied (batch- or time-specific) and in-depth time-dependent dosimetric signal behaviors can be established for film scanned outside of the recommended 16-24h post-irradiation window. We generated guidelines based on our findings to simplify film handling and analysis and provide tabulated dose- and time-dependent correction factors to achieve this without reducing the accuracy of dose determination.

Variability and associated uncertainty in image analysis for soiling characterization in solar energy systems

The accumulation of soiling on photovoltaic modules and on the mirrors of concentrating solar power systems causes non-negligible energy losses with economic consequences. These challenges can be mitigated, or even prevented, through appropriate actions if the magnitude of soiling is known. Particle counting analysis is a common procedure to characterize soiling, as it can be easily performed on micrographs of glass coupons or solar devices that have been exposed to the environment. Particle counting does not, however, yield invariant results across institutions. The particle size distribution analysis is affected by the operator of the image analysis software and the methodology utilized. The results of a round-robin study are presented in this work to explore and elucidate the uncertainty related to particle counting and its effect on the characterization of the soiling of glass surfaces used in solar energy conversion systems. An international group of soiling experts analysed the same 8 micrographs using the same open-source ImageJ software package. The variation in the particle analyses results were investigated to identify specimen characteristics with the lowest coefficient of variation (CV) and the least uncertainty among the various operators. The mean particle diameter showed the lowest CV among the investigated characteristics, whereas the number of particles exhibited the largest CV. Additional parameters, such as the fractional area coverage by particles and parameters related to the distribution's shape yielded intermediate CV values. These results can provide insights on the magnitude inter-lab variability and uncertainty for optical and microscope-based soiling monitoring and characterization.

Predicting Carbonate Chemistry on the Northwest Atlantic Shelf Using Neural Networks

AbstractThe Northwest Atlantic Shelf (NAS) region has experienced accelerated warming, heatwaves, and is susceptible to ocean acidification, yet also suffers from a paucity of carbonate chemistry observations, particularly at depth. We address this critical data gap by developing three different neural network models to predict dissolved inorganic carbon (DIC) and total alkalinity (TA) in the NAS region from more readily available hydrographic and satellite data. The models predicted DIC withr2between 0.913–0.963 and root mean square errors (RMSE) between 15.4–23.7 (μmol kg−1) and TA withr2between 0.986–0.983 and RMSE between 9.0–10.4 (μmol kg−1) on an unseen test data set that was not used in training the models. Cross‐validation analysis revealed that all models were insensitive to the choice of training data and had good generalization performance on unseen data. Uncertainty in DIC and TA were low (coefficients of variation 0.1%–1%). Compared with other predictive models of carbonate system variables in this region, a larger and more diverse data set with full seasonal coverage and a more sophisticated model architecture resulted in a robust predictive model with higher accuracy and precision across all seasons. We used one of the models to generate a reconstructed seasonal distribution of carbonate chemistry fields based on DIC and TA predictions that shows a clear seasonal progression and large spatial gradients consistent with observations. The distinct models will allow for a range of applications based on the predictor variables available and will be useful to understand and address ocean sustainability challenges.

High-consistent optical fiber photoacoustic generator with carbon nanoparticles-PDMS composite

Optical fiber photoacoustic (PA) probe is considered to have great prospects in high resolution invasive imaging due to the advantages of flexible, miniaturized broadband ultrasonic excitation. Unfortunately, more attentions are currently focused on the fabrication of the PA probe with a high PA conversion efficiency, instead of the consistency of the developed probe that is of great importance for practical applications. In this paper, in consideration of the coating thickness and flatness closely concerned with the consistency, a number of PA probes with 15 wt.% carbon nanoparticles (CNPs) and polydimethylsiloxane (PDMS) composite were fabricated by a spin-transfer method with the help of transferring uniformly spin-coated film on the endface of an optical fiber. Underwater ultrasonic detection showed that the fabricated probes exhibited a good consistency with the corresponding lower coefficients of variation of 1.7%, 1.4% and 1.1% for the sound pressure, center frequency and bandwidth, sharply reduced by 89%, 72% and 81% in comparison with the commonly used dip-coating probes tested in this work. Also, due to the thinner film obtained through the presented fabrication method, the maximum PA pressure value of 1.04 MPa with a -6 dB bandwidth of 54.2 MHz was achieved, which further demonstrates a great potential in high-resolution ultrasound imaging utilizing multiple probes with high consistency.

Acute effect of short-term immobilization on lower leg muscle tissue hardness in healthy adults.

Previous studies have reported altered neural activity in the motor cortex after short-term cast immobilization, even in healthy participants. However, the effects of short-term movement restriction on tissue structure are not well understood. To investigate the effects of short-term lower limb immobilization on muscle tissue hardness. Seventeen healthy participants were enrolled in the study. Each participant's non-dominant lower limb was fixed with a soft bandage and medical splint for 10 h. Gastrocnemius muscle tissue hardness was measured using a tissue hardness meter before cast application and immediately after cast removal. Measurements were performed five times for each lower limb, and the three values with the lowest coefficient of variance were adopted as the value of muscle tissue hardness. Gastrocnemius muscle tissue hardness in the immobilized limb was lower after cast removal than that before cast application (from 53.6 to 51.8; p< 0.01), whereas the non-fixed limb showed an increase in muscle tissue hardness at the end of the experiment (from 52.9 to 54.3; p= 0.03). The findings indicate that 10 h movement restriction induced a reduction in muscle tissue hardness, suggesting acute adverse effects of cast immobilization for orthopedic treatment.

The design of a camera-based fisheries-independent survey for untrawlable habitat in the Gulf of Alaska

Biomass and size composition estimates from the fishery independent biennial Alaska Fisheries Science Center Resource Assessment and Conservation Engineering Division’s Groundfish Assessment Program Gulf of Alaska bottom trawl survey are an integral component of stock assessments and management of fishes in the region. A substantial proportion of the seafloor in the Gulf of Alaska survey area consists of rocky, high-relief habitat that is not accessible to trawl survey gear and is important habitat for many harvested fish species, especially rockfishes (Sebastes spp.). Survey estimates of groundfish abundance from trawlable grounds are expanded across the entire region. Therefore, survey abundance estimates could potentially be biased as a result of sampling that does not spatially represent all of the available habitat circumscribed by the Gulf of Alaska study area. Mapping the extent of the untrawlable habitat is a critical step toward understanding the scale of these potential biases and would benefit the design of a future untrawlable habitat survey. Several previous efforts have provided trawlability maps for part or all of the Gulf of Alaska based on different data inputs. In the present work, we compile two previously published untrawlable habitat maps with three other relevant data sources to create a new untrawlable habitat map, and use this map in conjunction with density estimates from existing underwater camera studies to investigate the feasibility of an untrawlable habitat rockfish survey in the Gulf of Alaska. An analysis of 1 km2 grids sampled more than once with a lowered camera system suggested that a single-stage sampling design (one camera transect per grid) would be most effective. Post-stratification analysis showed that either a simple depth stratification or stratification based on species distribution models provided lower coefficient of variation (CV) values at a given sample size compared to random sampling. Furthermore, a target CV of 25 % could be reached for a camera survey of dusky rockfish, northern rockfish, or Pacific ocean perch with less than 200 lowered camera transects if a stratification scheme based on species distribution models was used.

Conventional or Shariah Compliant Investment: Performance Evaluation of Mutual Funds in Pakistan

The current study was initiated to compare the performance of conventional and Shariah-compliant mutual funds in Pakistan, keeping in view the contradictory opinions found in the literature in this regard. The data utilized to conduct the analysis covered the time span 2013-2021. Assessment of risk and return tradeoff was made with three ratios, namely Jenson’s alpha, Treynor ratio, and Sharpe ratio by evaluating the monthly returns of conventional and Shariah-compliant mutual funds. The findings revealed that Shariah-compliant mutual funds outperformed conventional funds in terms of absolute risk measure, higher Sharpe ratio, and low coefficient of variation. While, in terms of funds’ exposure to systematic risk, mixed results were obtained for both types of funds. The results produced sufficient information about the risks and returns associated with the two kinds of mutual funds which would enable fund managers and investors to make informed decisions while selecting the best mutual fund, thus generating maximum returns and with minimum risks.

663-P: Dynamic Real-Time Relationships among Glucose and Cognitive Performance in Diverse Adults with T1D

Introduction: Blood glucose (BG) regulation is linked to cognitive performance among people with diabetes. Most studies are cross-sectional and limited to adults with T2D. Pairing continuous glucose monitoring (CGM) with ambulatory cognitive tests, we examined real-time bidirectional associations between BG and cognition in everyday life among adults with T1D. Methods: Participants wore a blinded CGM for 10-14 days and completed ambulatory cognitive tests 5-6 times daily. Using dynamic structural equation modeling, we evaluated within-person bidirectional relationships between BG and cognition over sequential 3-hr periods. BG metrics included mean BG, time in range (TIR; 70-180 mg/dL), % time in low (50-69 mg/dL), high (181-250 mg/dL) and very high BG (&amp;gt;250 mg/dL), and coefficient of variation (CV). Cognitive variables included processing speed and sustained attention. Results: Among 182 adults with T1D (40±14 yrs, 46% male, 41% Latino, 29% White, 15% Black), greater mean BG (beta=0.03), lower TIR (beta=-0.03), and more time in high (beta=0.03) and very high BG (beta=0.03) predicted slower processing speed 3 hrs later (ps&amp;lt;.05); no BG metric predicted sustained attention ability. Surprisingly, slower processing speed predicted lower mean BG (beta=-0.05), more TIR (beta=0.04) and less time in high (beta=-0.01) and very high BG (beta=-0.04) over the next 3 hrs. Reduced sustained attention predicted more time in very high BG (beta=-0.01) and lower CV (beta=0.03) (ps&amp;lt;0.05). Conclusion: Our findings suggest that poorer BG regulation negatively influences processing speed over short time frames. Slower processing speed predicted subsequent improvements in CGM metrics, suggesting that individuals may take steps to correct BG when experiencing cognitive effects of poor BG regulation. These short-term relationships illuminate opportunities for in-the-moment interventions. Disclosure C.J.Hoogendoorn: None. D.Spruijt-metz: None. E.Pyatak: Research Support; Abbott Diabetes. J.S.Gonzalez: Consultant; Virta Health Corp. R.Hernandez: None. S.Schneider: None. A.L.Peters: Advisory Panel; Abbott Diabetes, Medscape, Novo Nordisk, Vertex Pharmaceuticals Incorporated, Zealand Pharma A/S, Research Support; Abbott Diabetes, Dexcom, Inc., Insulet Corporation, Stock/Shareholder; Omada Health, Inc., Livongo. J.P.Crandall: Research Support; Abbott. G.Crespo-ramos: None. H.Jin: None. L.T.Pham: None. S.Agarwal: Advisory Panel; Medtronic, Consultant; Beta Bionics, Inc., Research Support; Abbott Diabetes, Dexcom, Inc. Funding National Institutes of Health (R01DK121298, P30DK020541, P30DK111022)

1450-P: Profiles of Glycemic Control in People with Type 1 Diabetes Using CGM—A Clustering Approach in the SFDT1 Study

CGM-derived data are usually analyzed in silos, metric by metric, for diabetes care or therapeutic strategy. Simultaneous analysis of the various dimensions of glycemic control would allow a more comprehensive overview. We analyzed data of people with type 1 diabetes (PWT1D) in the SFDT1 cohort study. A K-means clustering model was developed with HbA1c, coefficient of variation (CV), time in range (TIR), time below 70 mg/dl (TBR), Gold score and Glycemic Risk Index (GRI). We included 618 participants (53% men, age 41±14 years) from 20 centres in France. The optimal model had 3 clusters. The “Euglycemia” cluster (n=280, 45%) was characterized by a high TIR (mean 69.3%); low TBR ​​(4.2%), TAR (time above 180 mg/dl: 26.5%), CV (35.7%), HbA1c (7.0%) and GRI (36.4) values. The “Hyperglycaemia" cluster (n=197, 32%) was characterized by high TAR (56.5%), GRI (71.8) and HbA1c (8.5%) and low TIR (40.3%), TBR (3.2%) and Gold score (2.3). The “Hypoglycemia” cluster (n=141, 23%) was characterized by high TBR (15.8%), CV (46.1%), GRI (69.2) and Gold score (3.0). Participants in the “Hyperglycemia” cluster were younger, socially vulnerable, and had more frequent hypertension than those in the “Euglycemia” cluster. To conclude, we identified three distinct, clinically relevant glycemic control profiles, enabling better characterization of PWT1D and, thus, more personalised management. Disclosure E.Cosson: Board Member; Abbott, Medtronic. G.A.Aguayo: None. L.Sablone: None. M.Huet: None. J.Riveline: Board Member; Abbott Diabetes, Medtronic, Dexcom, Inc., Novo Nordisk, Eli Lilly and Company, Sanofi. G.Fagherazzi: Advisory Panel; Roche Diabetes Care, Consultant; AbbVie Inc., Lilly. Sfdt1 study team: n/a.

Reproducibility and repeatability of biventricular function/volume and strain parameters by 2D and 4D stress echocardiography in adult patients with repaired TOF

Abstract Funding Acknowledgements Type of funding sources: None. Background The use of 2D and 4D during stress echocardiography to undertake complex measures in complex patients like patients with repaired TOF is challenging and the validity of these measures is not known yet. Methods For test-retest variability, 20 patients with repaired TOF with no or mild pulmonary regurgitation were selected randomly and underwent a cardiopulmonary exercise test (CPET) with echocardiography. Intra-observer variability study was performed for all 20 patients by the same observer. Interobserver variability study was performed for 5 patients by different experienced observer. Intraclass correlation coefficient (ICC), and coefficients of variation (COV) were used to quantify reproducibility and variability. Results For 2D measures, better reproducibility was observed for semiautomated 2D strain measures than 2D functional measures for biventricular systolic function at baseline and during the stress (ICC&amp;gt;.90 vs &amp;gt;.70, p&amp;lt;0.001), with least COV was observed (COV&amp;lt;10%). 4D semiautomated volumetric measures demonstrated less reproducibility during stress with highest COV was observed for 4D RV volume parameters (COV, 35%), followed by 4D LV volume parameters (COV, 27%). CPET had an excellent agreement of all measures (ICC &amp;gt;.90). with very low COV (&amp;lt;10%). Conclusions Semiautomated echo measures outperformed manual measures during stress echocardiography and can be performed with acceptable reproducibility. Variability is at highest for 4D semiautomated measures despite good reproducibility, while lowest variability was observed for 2D semiautomated measures of myocardial deformation.

How and when to measure pH in IVF culture media: validation of a portable blood gas analyzer in two IVF culture dishes for time lapse and conventional incubators.

Maintaining a stable pH at optimal level in human embryo culture media is crucial for embryo development but poses a challenge for all IVF laboratories. We validate analytically reliable conditions for pH measurement that are as close as possible to the embryo microenvironment during IVF. This was a multicentric study. A Siemens EPOC portable blood gas analyzer was used. The analytical validation was carried out under the culture medium (Global Total HSA®) conditions of use (microdroplets, under oil overlay, in a IVF incubator with (EmbryoScope®) or without a time lapse system (K system G210+®) and using IVF dishes. The validation included repeatability ("within-run" precision), total precision (between-day precision), trueness based on inter-laboratory comparison, inaccuracy based on external quality assessment and comparison to the reference technique. We also assessed the pre-analytical medium incubation time required to obtain a target value. A measurement after an incubation period of 24 to 48 h is more representative of the pH to which the embryo will be exposed throughout the culture. The "within-run" and "between-day" precision show very low coefficients of variation (CV%): 0.17 to 0.22% and 0.13 to 0.34%, respectively, with IVF culture media. Trueness (% bias) range from - 0.07 to - 0.03%. We demonstrate good correlation between EPOC and reference pH electrode with an overestimation of 0.03 pH units of EPOC. Our method demonstrates good analytical performance for IVF laboratories wishing to implement a robust quality assurance system to monitor pH in embryo culture media. Compliance with stringent pre-analytical and analytical conditions is essential.

The soil organic carbon: Clay ratio in North Devon, UK: Implications for marketing soil carbon as an asset class

AbstractBuilding up stocks of agricultural soil organic carbon (SOC) can improve soil conditions as well as contribute to climate change mitigation. As a metric, the ratio of SOC to clay offers a better predictor of soil condition than SOC alone, potentially providing a benchmark for ecosystem service payments. We determined SOC:clay ratios for 50 fields in the North Devon UNESCO World Biosphere Reserve using 30 cm soil cores (divided into 0–10 cm and 10–30 cm depth samples), with soil bulk density, soil moisture and land‐use history recorded for each field. All the arable soils exceeded the minimum desirable SOC:clay ratio threshold, and the ley grassland soils generally exceeded it but were inconsistent at 10–30 cm. Land use was the primary factor driving SOC:clay ratios at 0–10 cm, with permanent pasture fields having the highest ratios followed by ley grass and then arable fields. Approximately half of the fields sampled had potential for building up SOC stock at 10–30 cm. However, at this depth, the effect of land use is significantly reduced. Within‐field variability in SOC and clay was low (coefficient of variation was ~10%) at both 0–10 cm and 10–30 cm, suggesting that SOC:clay ratios precisely characterized the fields. Due to the high SOC:clay ratios found, we conclude that there is limited opportunity to market additional carbon sequestration as an asset class in the North Devon Biosphere or similar areas. Instead, preserving existing SOC stocks would be a more suitable ecosystem service payment basis.

The effect of low-abundance OTU filtering methods on the reliability and variability of microbial composition assessed by 16S rRNA amplicon sequencing.

PCR amplicon sequencing may lead to detection of spurious operational taxonomic units (OTUs), inflating estimates of gut microbial diversity. There is no consensus in the analytical approach as to what filtering methods should be applied to remove low-abundance OTUs; moreover, few studies have investigated the reliability of OTU detection within replicates. Here, we investigated the reliability of OTU detection (% agreement in detecting OTU in triplicates) and accuracy of their quantification (assessed by coefficient of variation (CV)) in human stool specimens. Stool samples were collected from 12 participants 22-55 years old. We applied several methods for filtering low-abundance OTUs and determined their impact on alpha-diversity and beta-diversity metrics. The reliability of OTU detection without any filtering was only 44.1% (SE=0.9) but increased after filtering low-abundance OTUs. After filtering OTUs with <0.1% abundance in the dataset, the reliability increased to 87.7% (SE=0.6) but at the expense of removing 6.97% reads from the dataset. When filtering was based on individual sample, the reliability increased to 73.1% after filtering OTUs with <10 copies while removing only 1.12% of reads. High abundance OTUs (>10 copies in sample) had lower CV, indicating better accuracy of quantification than low-abundance OTUs. Excluding very low-abundance OTUs had a significant impact on alpha-diversity metrics sensitive to the presence of rare species (observed OTUs, Chao1) but had little impact on relative abundance of major phyla and families and alpha-diversity metrics accounting for both richness and evenness (Shannon, Inverse Simpson). To increase the reliability of microbial composition, we advise removing OTUs with <10 copies in individual samples, particularly in studies where only one subsample per specimen is available for analysis.

Optimizing reduction of western blotting analytical variations: Use of replicate test samples, multiple normalization methods, and sample loading positions

Western blot (WB) analysis is widely used, but obtaining consistent results can be problematic, especially when using multiple gels. This study examines WB performance by explicitly applying a method commonly used to test analytical instrumentation. Test samples were lysates from RAW 264.7 murine macrophages treated with LPS to activate MAPK and NF-kB signaling targets.Samples from the pooled cell lysates placed in every lane on multiple gels were analyzed by WBs for levels of p-ERK, ERK, IkBβ and non-target protein. Different normalization methods and sample groupings were applied to the density values and the resulting coefficients of variation (CV) and ratios of maximal to minimal values (Max/Min) were compared. Ideally with identical sample replicates the CVs would be 0 and the Max/Min 1; deviation indicating introduction of variability by the WB process. Common normalizations to reduce analytical variance, total lane protein, % Control, and p-ERK/ERK ratios, did not have the lowest CVs or Max/Min values. Normalization using the sum of target protein values combined with analytical replication most effectively reduced variability, resulting CV and Max/Min values as low as 5–10% and 1.1. These methods should allow reliable interpretation of complex experiments that require samples to be placed on multiple gels.

Assessment of the tensile behavior of twisted steel connectors for masonry retrofitting

The paper presents an experimental investigation on the tensile behavior of twisted stainless-steel bars considering different parameters that could affect their performance, namely the bar diameter (8, 10, 12 mm), the embedment depth, the position within the wall (installed into brick or in a T-mortar joint), the strength of the masonry and the type of loading (monotonic or cyclic load). Experimental results showed very good performance with reliable results associated to low coefficient of variation of the loads and very limited damage of the base material. The load–displacement curves showed a good ductility, an excellent superposition between monotonic and cyclic tests and an extended plateau at ultimate load. Among the different investigated parameters, the position within the wall was the most influential one, with higher loads associated to mid-brick location of the bar. Finally, based on the experimental results a user-friendly equation is proposed to predict the ultimate tensile load.