Important Source Of Variation Research Articles

(Nanocarbons Division SES Young Investigator Award) Surface Chemistry of Nanocarbon Field-Effect Transistors: From Fundamental Physics to Biosensing

Conductive carbon nanomaterials are particularly well-suited to form field-effect biosensors (bioFETs) because they are stable in aqueous media and can be chemically coupled to biomolecules. Their reduced dimensionality, either 2D (graphene) or 1D (carbon nanotubes), is key to their sensitivity: because they are entirely surfaces, these materials present remarkable electrical transport properties that are easily altered by microscopic surface interactions. Biochemical processes occurring in close proximity to their surface can therefore be transduced as changes in their electrical conductance. Selectivity for specific biochemical events, however, must be engineered via functionalization of the nanomaterial, i.e. by modifying its surface with bioactive or biorecognition elements (e.g., antibodies, aptamers, enzymes, polymer layer). Our group recently analyzed a corpus of studies presenting graphene field-effect transistors (GFETs) as bioanalytical sensors for the quantitative detection of biomarkers in the form of nucleic acids, proteins, ions or small molecules [1]. We found a striking variance in the reported sensing performance between these studies, that could not be explained by controlling for differences in graphene material, analyte type and for evolution over the years. Our hypothesis is that the lack of microscopic control on the biointerface is likely the most important source of variation in such bioFETs, highlighting the critical need to improve our knowledge and control of the functionalization of nanocarbon materials.In this talk, I will discuss our work investigating the interplay between surface chemistry and electrical properties in nanocarbon field-effect transistors. In the first part, I will focus on covalent additions using aryldiazonium salts. I will review what we have learned on the fundamental physics of this chemistry from experiments and simulations on carbon nanotube devices [2-5], in particular on its disruptive character because of the formation of sp 3 defects in the carbon lattice. More recently, we investigated this same chemistry on GFET devices and observed a heterogeneous response in their electrical conductance. Aiming to solve this, we developed a novel approach to precisely trigger and stop the reaction in situ using the applied gate voltage [6], enabling unprecedented control on the functionalization rate and yield on GFETs. In the second part, I will describe our ongoing efforts to characterize and control the biofunctionalization of GFETs through non-covalent pyrene derivatives, using a combination of electrical measurements, microscopy and spectroscopy techniques, and theoretical simulations. Finally, I will discuss our ongoing translational projects in oncology, on adapting nanocarbon-based bioFETs in cancer diagnostics applications.[1] Béraud et al, Analyst 146 (2), 403-428 (2021)[2] Bouilly et al, Applied Physics Letters 101 (5), 053116 (2012)[3] Bouilly et al, ACS nano 9 (3), 2626-2634 (2015)[4] Bouilly et al, Nano Letters 16 (7), 4679-4685 (2016)[5] Côté et al, Physical Chemistry Chemical Physics 24 (7), 4174-4186 (2021)[6] Bazan et al, Nano Letters 22 (7), 2635-2642 (2022)

On-farm performance evaluation of indigenous sheep in the Gedeo zone, Southern Ethiopia

ABSTRACT This study was conducted to identify the productive and reproductive performance of sheep in the Gedeo zone. Flock of 50 households was randomly selected for a household survey. A total of 189 lambs’ growth data and reproductive traits from 125 ewes were collected. A general linear model was employed for the analysis. Sheep flock size shows (8.6 ± 0.11) a significant difference (P < 0.05) among age categories. Weight at birth (3.01 ± 0.3 kg), weaning (14.2 ± 0.9 kg) and six months (22.4 ± 1.1) of lambs were significant (P < 0.01) among parties, birth type, lamb sex and birth season. Body size and growth rate were important traits for breeding sheep selection. The average age at first lambing and lambing interval was 12.3 ± 0.12 and 7.7 ± 0.06, respectively. Other reproductive traits, such as fertility rate (76.7%), litter size (1.51), weaning percentage (81.6%) and lamb survival rate (86.2%), were observed. In conclusion: parity, birth type, lamb sex and birth season are important sources of variation in sheep growth performance that were considered fixed effects during the analysis. Thus, as policy direction, genetic improvement combined with nutrition, health and participatory breeding would contribute to sheep genetic improvement that should be given proper attention.

Fission as a source of variation for group selection

Abstract Without heritable variation natural selection cannot effect evolutionary change. In the case of group selection, there must be variation in the population of groups. Where does this variation come from? One source of variation is from the stochastic birth–death processes that occur within groups. This is where variation between groups comes from in most mathematical models of group selection. Here, we argue that another important source of variation between groups is fission, the (generally random) group-level reproduction where parent groups split into two or more offspring groups. We construct a simple model of the fissioning process with a parameter that controls how much variation is produced among the offspring groups. We then illustrate the effect of that parameter with some examples. In most models of group selection in the literature, no variation is produced during group reproduction events; that is, groups “clone” themselves when they reproduce. Fission is often a more biologically realistic method of group reproduction, and it can significantly increase the efficacy of group selection.

Macroeconomic Impacts of Oil Price Shocks: Evidence from Iraq by Using Vector Autoregressive Model

Based on a VAR framework, Granger Causality Tests, Impulse Response Function and Variance Decomposition analysis on the annual data from 1970 to 2021, This study aims to demonstrate the effect of oil price fluctuations on GDP, imports, international reserves, and exports in Iraq. The Granger causality results demonstrated a unidirectional connection moving from oil price to imports, exports, international reserves, and GDP, this is an inevitable result because oil prices are determined in the international markets according to specific factors that do not include local economic variables. The variance decomposition result indicated that oil price changes are an important source of variation in the studied variables. Finally, the results of the impulse response function indicated that fluctuations in oil prices significantly impact GDP, exports, imports, and international reserves in Iraq. Therefore, we suggest that economic policymakers work seriously to develop practical plans to diversify the Iraqi economy instead of relying too heavily on oil revenues, which are characterized by sharp and continuous volatility, to avoid the negative effects of these fluctuations on the main macroeconomic variables in Iraq.

Muscle biopsy long-chain omega-3 polyunsaturated fatty acid compositions, IMF and FMP in Australian pasture-based Bowen Genetics Forest Pastoral Angus, Hereford, and Wagyu Beef Cattle

BackgroundWe investigated breed and gender variations in the compositions of long-chain (≥ C20) omega-3 polyunsaturated fatty acids (LC omega-3 PUFA), fat melting point (FMP) and intramuscular fat (IMF) contents in biopsy samples of the M. longissimus dorsi muscle of grazing beef cattle. The hypothesis that biopsy compositions of health-beneficial LC omega-3 PUFA, FMP and IMF in a pasture-based production system will vary with breed, was tested. Muscle biopsies were taken from 127 yearling pasture-based Angus, Hereford, and Wagyu heifers and young bulls exclusive to the Australian Bowen Genetics Forest Pastoral breeding stud averaging 12 ± 2.43 months of age and under the same management routine.ResultsBreed had a significant influence on IMF, FMP, and the compositions of oleic acid, α-linolenic acid (ALA), eicosapentaenoic (EPA), docosahexaenoic (DHA), docosapentaenoic (DPA), and total EPA + DHA + DPA in the M. longissimus dorsi muscle biopsies (P ≤ 0.03). The Wagyu breed had the highest (11.1%) and Hereford the lowest (5.9%) IMF (P = 0.03). The reverse trend was observed in FMP values where the Hereford breed had the highest (55 °C), Angus intermediate (46.5 °C), and Wagyu the lowest (33 °C) FMP. The Wagyu and Angus breeds had similar oleic fatty acid (18:1n-9) content, while the Hereford breed had the lowest (P < 0.01). The highest ALA, DPA, total EPA + DHA, total EPA + DHA + DPA and total ALA + EPA + DHA + DPA contents were detected in the Wagyu breed (P ≤ 0.03). The Hereford had similar EPA and DPA contents to the Angus (P ≥ 0.46). Total EPA + DHA + DPA contents in Wagyu, Angus, and Hereford were 28.8, 21.5, and 22.1 mg/100g tissue (P = 0.01), respectively. Sex was an important source of variation that influenced LC omega-3 PUFA composition, FMP and IMF, where yearling heifers had higher IMF (11.9% vs 5.3%), lower FMP (33°C vs 37°C), and higher LC omega-3 PUFA than bulls.ConclusionAll the results taken together indicate that the Wagyu breed at 28.8 mg/100g tissue, was the closest to meeting the Australia and New Zealand recommended source level threshold of 30 mg/100g tissue of health-beneficial ≥ C20 omega-3 FA content. Since gender was a significant determinant of LC omega-3 PUFA composition, IMF content and FMP, it should be factored into enhancement strategies of healthy meat eating quality traits in grazing cattle. These findings also suggest that the Bowen Genetics Forest Pastoral beef cattle studs are important sources of LC omega-3 PUFA that can be used to cover the deficit in these health claimable fatty acids in Western diets.

Knowledge attainment, learning approaches, and self-perceived study burnout among European veterinary students.

This study investigates the relationship between approaches to learning, self-perceived study burnout, and the level of knowledge among veterinary students. Veterinary educational programs are under regular development and would benefit greatly from detailed feedback on students' knowledge, proficiency, influencing factors, and coping mechanisms. The VetRepos consortium developed and calibrated an item repository testing knowledge across the entire veterinary curriculum. Two hundred forty-eight students from seven European veterinary institutions took the VetRepos test, comprising a subset of the repository. They also responded to a questionnaire assessing deep and unreflective learning approaches and self-perceived study burnout, represented by exhaustion and cynicism. Structural equation modeling analyzed the relationship between these latent traits and the VetRepos test score. The model failed the exact-fit test but was retained based on global fit indices, inter-item residual correlations, and standardized residual covariances. Root Mean Square Error of Approximation with robust standard errors and scaled test statistic was 0.049 (95% confidence interval 0.033-0.071), scaled and robust Comparative Fit Index 0.95 (0.90-0.98), and scaled Standardized Root Mean Square Residual 0.056 (0.049-0.071). Measurement invariance across study years was not violated (ΔCFI = 0.00, χ2 = 3.78, Δdf = 4, p = 0.44), but it could not be confirmed between genders or universities. The VetRepos test score regressed on the study year [standardized regression coefficient = 0.68 (0.62-0.73)], showed a negative regression on the unreflective learning approach [-0.25 (-0.47 to -0.03)], and a positive regression on the deep approach [0.16 (0.03-0.28)]. No direct association with perceived burnout was observed; however, a significant, medium-sized association was found between the unreflective approach and self-perceived study burnout. No significant differences in learning approaches or perceived burnout were found between study years. The most important source of variance in VetRepos test scores, unrelated to the study year, was the learning approach. The association between the VetRepos test score and self-perceived burnout was indirect. Future research should complement this cross-sectional approach with longitudinal and person-oriented studies, further investigating the relationship between study burnout and learning approaches.

138 Sire Differences for Blood Urea Nitrogen (BUN) in Hereford Cattle

Abstract Excess Nitrogen excretion is a growing concern worldwide within animal agriculture, and blood urea nitrogen (BUN; mg/dL) is known as a predictor of nitrogen excretion in cattle. The objective of this study was to determine sire differences in BUN within a population of Hereford steers. Steers (n = 74) were born between March and June of 2021 from a reference sire herd for The American Hereford Association in Western Nebraska. Sixteen different Hereford sires from The American Hereford Association reference sire program produced offspring used in this study. The steers entered an on-site feed intake unit and were fed a finishing diet consisting predominantly of corn, corn distiller grain, and corn silage. Animals were subjected to a 21-d warm-up period with a 55-d individual feed intake test period. Blood samples were collected on day 43 of the test period. Blood samples were then centrifuged to extract serum. The Urea Nitrogen (BUN) Colorimetric Detection Kit by Invitrogen was used for the assay. The average BUN concentration for all animals in this study was (0.492 ± 0.061 mg/dL). A generalized linear regression model was used to determine sire differences in BUN concentrations. Factors considered were sire and pen group. The sire with lowest least squared mean progeny BUN concentration estimate was (0.0362 ± 0.08 mg/dL; n = 4), and the highest was (0.605 ± 0.03 mg/dL; n = 7). Sire differences (P &amp;lt; 0.05; r2 = 0.36) were found to be important sources of variation as evidenced by its r2; however, pen group (P = 0.65; r2 &amp;lt; 0.05) appeared to have little impact on variation. The differences in sires indicate genetic differences could be leveraged to reduce excess nitrogen excretion in cattle populations.

Tree-ring isotopic composition reveals intraspecific variation in water use efficiency of Pinus pinaster Ait. provenances grown in common gardens

Key messageThe physiological responses expressed by variation in carbon and oxygen stable isotopes and iWUE in five provenances of maritime pine grown in four common gardens were primarily determined by genotype differences in phenotypic plasticity and secondarily by genotype.Given the impacts of climate change on forest resources and considering the slowness of evolutionary processes in trees, a need arises to understand the interplay between tree species adaptation to climate, genetic variation, and their impact on tree growth and productivity. Broadening knowledge of the capacity of tree populations to respond to climate-related disturbances is a prerequisite for the development of resilience strategies, including assisted migration and climate-smart forestry. This study tests the physiological ability of different maritime pine provenances, comparing Mediterranean (Corsica, Sardinia, and Tuscany) and Atlantic (Portugal) provenances, to adapt to progressively drier conditions that have occurred in the last thirty years. Four provenance trials with randomized blocks of the five maritime pine provenances were used as test sites in Sardinia (Italy). Wood cores were collected from the 40-year-old plants. Cores were split into five-year segments to determine provenance-related variations in carbon and oxygen stable isotopes and provide information on long-term patterns in intrinsic water use efficiency (iWUE). The provenance × site interaction was the most important source of variation, meaning that the genotypes responded differently to the planting sites. Considering the main effects, both genotype and environmental conditions at the planting sites influenced stable isotope composition in tree rings. This suggests that iWUE was determined by phenotypic plasticity that differed among genotypes. In contrast, provenance responses were stable with time, and the provenance × site interaction was stable across time periods. These findings suggest that provenance selection to improve iWUE in maritime pine may need to consider site conditions but point more to soil conditions than to climate. In any case, they limit our ability to recommend maritime pine provenances based on iWUE until the missing site factors can be identified.

Effect of a Multifaceted Intervention on the Incidence of Hemodialysis Catheter Dysfunction in a National Stepped-Wedge Cluster Randomized Trial

Effective strategies to prevent hemodialysis (HD) catheter dysfunction are lacking and there is wide variation in practice. In this post hoc analysis of the REDUcing the burden of dialysis Catheter ComplicaTIOns: a national (REDUCCTION) stepped-wedge cluster randomized trial, encompassing 37 Australian nephrology services, 6361 participants, and 9872 catheters, we investigated whether the trial intervention, which promoted a suite of evidence-based practices for HD catheter insertion and management, reduced the incidence of catheter dysfunction, which is defined by catheter removal due to inadequate dialysis blood flow. We also analyzed outcomes among tunneled cuffed catheters and sources of event variability. A total of 873 HD catheters were removed because of dysfunction over 1.12 million catheter days. The raw incidence was 0.91 events per 1000 catheter days during the baseline phase and 0.68 events per 1000 catheter days during the intervention phase. The service-wide incidence of catheter dysfunction was 33% lower during the intervention after adjustment for calendar time (incidence rate ratio= 0.67; 95% confidence interval [CI], 0.50-0.89; P= 0.006). Results were consistent among tunneled cuffed catheters (adjusted incidence rate ratio= 0.68; 95% CI, 0.49-0.94), which accounted for 75% of catheters (n= 7403), 97.4% of catheter exposure time and 88.2% of events (n= 770). Among tunneled catheters that survived for 6 months (21.5% of tunneled catheters), between 2% and 5% of the unexplained variation in the number of catheter dysfunction events was attributable to service-level differences, and 18% to 36% was attributable to patient-level differences. Multifaceted interventions that promote evidence-based catheter care may prevent dysfunction, and patient factors are an important source of variation in events.

The Importance of Fed Chair Speeches as a Monetary Policy Tool

I estimate the effects of Federal Open Market Committee (FOMC) announcements, post-FOMC press conferences, and speeches and Congressional testimony by the Fed chair on stock prices, Treasury yields, and interest rate futures from 1988 to 2019. I show that for all but the very shortest-maturity interest rate futures, Fed chair speeches are more important than FOMC announcements. My results suggest that the previous literature's focus on FOMC announcements has ignored the most important source of variation in US monetary policy.

Substrate-specific effects of natural genetic variation on proteasome activity.

Protein degradation is an essential biological process that regulates protein abundance and removes misfolded and damaged proteins from cells. In eukaryotes, most protein degradation occurs through the stepwise actions of two functionally distinct entities, the ubiquitin system and the proteasome. Ubiquitin system enzymes attach ubiquitin to cellular proteins, targeting them for degradation. The proteasome then selectively binds and degrades ubiquitinated substrate proteins. Genetic variation in ubiquitin system genes creates heritable differences in the degradation of their substrates. However, the challenges of measuring the degradative activity of the proteasome independently of the ubiquitin system in large samples have limited our understanding of genetic influences on the proteasome. Here, using the yeast Saccharomyces cerevisiae, we built and characterized reporters that provide high-throughput, ubiquitin system-independent measurements of proteasome activity. Using single-cell measurements of proteasome activity from millions of genetically diverse yeast cells, we mapped 15 loci across the genome that influence proteasomal protein degradation. Twelve of these 15 loci exerted specific effects on the degradation of two distinct proteasome substrates, revealing a high degree of substrate-specificity in the genetics of proteasome activity. Using CRISPR-Cas9-based allelic engineering, we resolved a locus to a causal variant in the promoter of RPT6, a gene that encodes a subunit of the proteasome's 19S regulatory particle. The variant increases RPT6 expression, which we show results in increased proteasome activity. Our results reveal the complex genetic architecture of proteasome activity and suggest that genetic influences on the proteasome may be an important source of variation in the many cellular and organismal traits shaped by protein degradation.

Herd and animal factors affect the variability of total and differential somatic cell count in bovine milk.

The aim of this study was to quantify some environmental (individual herds, herd productivity, milking system, and season) and animal factors [individual animals, breed, days in milk (DIM) and parity] on the variability of the log-10 transformation of somatic cell count (LSCC) and differential somatic cell count (DSCC) on individual bovine milk. A total of 159,360 test-day records related to milk production and composition were extracted from 12,849 Holstein-Friesian and 9,275 Simmental cows distributed across 223 herds. Herds were classified into high and low productivity, defined according to the average daily milk net energy output (DMEO) yielded by the cows. Data included daily milk yield (DYM; kg/d), milk fat, protein, lactose, SCC, and DSCC, and information on herds (i.e., productivity, milking system). The daily production of total and differential somatic cells in milk was calculated and then log-10 transformed, obtaining DLSCC and DLDSCC, respectively. Data were analyzed using a mixed model including the effects of individual herd, animal, repeated measurements intra animal as random, and herd productivity, milking system, season, breed, DIM, parity, DIM × parity, breed × season, DIM × milking system and parity × milking system as fixed factors. Herds with a high DMEO were characterized by a lower content of LSCC and DSCC, and higher DLSCC and DLDSCC, compared to the low DMEO herds. The association between milking system and somatic cell traits suggested that the use of the automatic milking systems would not allow for a rapid intervention on the cow, as evidenced by the higher content of all somatic cell traits compared to the other milking systems. Season was an important source of variation, as evidenced by high LSCC and DSCC content in milk during summer. Breed of cow had a large influence, with Holstein-Friesian having greater LSCC, DSCC, DLSCC, and DLDSCC compared to Simmental. With regard to DIM, the variability of LSCC was mostly related to that of DSCC, showing an increase from calving to the end of lactation, and suggesting the higher occurrence of chronic mastitis in cows toward the end of lactation. All the somatic cell traits increased across number of parities, possibly because older cows may have increased susceptibility to intramammary infections.

Influence of temporal resolution on computed tomography feature-tracking strain measurements

PurposeTemporal resolution significantly affects strain values demonstrated by Magnetic resonance feature-tracking and speckle-tracking echocardiography. We investigated the influence of R-R interval reconstruction increments on left ventricular (LV) and left atrial (LA) strain measurements of Computed tomography feature-tracking (CT-FT). MethodsSubjects who underwent retrospective electrocardiogram-gated coronary CT angiography (CCTA) were retrospectively included, and CCTA images were reconstructed in 5% and 10% steps throughout the entire cardiac cycle (0–100% R-R interval). LV global longitudinal strain (GLS), circumferential strain (GCS), radial strain (GRS), LA GLS, ejection fraction (EF), and left atrioventricular coupling indices were computed. We evaluated the consistency and variability of continuous variables between the two reconstruction increment groups, the demarcation between the LA conduit and contraction phases, and observer reproducibility in 20 randomly selected participants. ResultsEighty-one participants with or without cardiac disease were included. The reconstruction increment of the R-R interval significantly affected the CT-FT-derived strain values. The 5% R-R increment resulted in significantly larger absolute strain values. LV GRS had the greatest difference between the two groups. In the subgroups with heart rates greater than 80 beats per minute or impaired cardiac function, group differences were attenuated, especially for LV GLS, LV GRS, and LA GLS. The prevalence of definite demarcation between the LA conduit and contraction phases was significantly higher in the 5% R-R reconstruction increment group than in the 10% R-R reconstruction increment group. The average heart rate during CCTA scanning was a strong risk factor for indefinite demarcation, which is independent of LVEF. As average heart rate increased, so did the incidence of indefinite demarcation between the LA conduit and contraction phases. The observer reproducibility of LV and LA strain values was independent of the R-R reconstruction increment. ConclusionReconstruction increment of the R-R interval is an important source of variation in LV and LA CT-FT strain values, especially with low heart rate and preserved cardiac function. It is essential to control the heart rate and apply a narrow R-R reconstruction increment to quantify phasic LA strain.

The El Niño Southern Oscillation drives multidirectional inter-reef larval connectivity in the Great Barrier Reef.

The El Niño Southern Oscillation (ENSO) is the strongest source of interannual global climate variability, and extreme ENSO events are projected to increase in frequency under climate change. Interannual variability in the Coral Sea circulation has been associated with ENSO, although uncertainty remains regarding ENSO's influence on hydrodynamics and larval dispersal in the adjacent Great Barrier Reef (GBR). We investigated larval connectivity during ENSO events from 2010 to 2017 throughout the GBR, based on biophysical modelling of a widespread predatory reef fish, Lutjanus carponotatus. Our results indicate a well-connected system over the study period with high interannual variability in inter-reef connectivity associated with ENSO. Larval connectivity patterns were highly correlated to variations in the Southern Oscillation Index (SOI). During El Niño conditions and periods of weak SOI, larval dispersal patterns were predominantly poleward in the central and southern regions, reversing to a predominant equatorward flow during very strong SOI and extreme La Niña conditions. These ENSO-linked connectivity patterns were associated with positive connectivity anomalies among reefs. Our findings identify ENSO as an important source of variation in larval dispersal and connectivity patterns in the GBR, which can influence the stability of population dynamics and patterns of biodiversity in the region.

Differential Gene Expression Analysis and Gene Ontology in Triploid and Diploid Pocillopora Acuta

Corals are marine invertebrates that are facing life-threatening environmental stressors due to climate change. Polyploidy can, in such cases, be an important source of variation and adaptation in corals and other species. Polyploidy is the genomic condition wherein the cells of a normally diploid organism have more than one pair of chromosomes. Pocillopora acuta, also known as the cauliflower coral, is a brooding coral that can also reproduce asexually. It is a stress-sensitive coral, which means it shows clear physiological changes in response to environmental stressors like temperature, salinity, and pH. In this study, about 60% of the stony coral Pocillopora acuta samples collected from Kāneʻohe Bay, Oahu, HI, were triploid. The aim of this study was to identify the differences in gene expression patterns between triploid cluster 1 (T1), triploid cluster 2 (T2), and diploid samples (D) of P. acuta. Pairwise comparisons were carried out between all categories: T1 vs. D, T2 vs. D, and T1 vs. T2. While there were a large number of genes exhibiting similar expression patterns in both triploid clusters, many genes were differentially regulated in T1 when compared to T2. This result provides evidence suggesting that the two triploid lineages originated from separate triploidization events in Kāneʻohe Bay. The differentially expressed genes shared between these two triploid lineages, when compared to the diploid coral lineage, suggests changes in cellular physiology as a result of polyploidization. Functional analysis of the P. acuta genes can provide deeper insight into the specific, differentially regulated molecular functions and biological processes in triploids when compared to diploid P. acuta. Future studies involving comparative functional enrichment analysis with more triploid and diploid samples of P. acuta will provide more insight into events that caused triploidization and the coral’s response to environmental stressors.

Gastrointestinal helminths increase Bordetella bronchiseptica shedding and host variation in supershedding.

Co-infected hosts, individuals that carry more than one infectious agent at any one time, have been suggested to facilitate pathogen transmission, including the emergence of supershedding events. However, how the host immune response mediates the interactions between co-infecting pathogens and how these affect the dynamics of shedding remains largely unclear. We used laboratory experiments and a modeling approach to examine temporal changes in the shedding of the respiratory bacterium Bordetella bronchiseptica in rabbits with one or two gastrointestinal helminth species. Experimental data showed that rabbits co-infected with one or both helminths shed significantly more B. bronchiseptica, by direct contact with an agar petri dish, than rabbits with bacteria alone. Co-infected hosts generated supershedding events of higher intensity and more frequently than hosts with no helminths. To explain this variation in shedding an infection-immune model was developed and fitted to rabbits of each group. Simulations suggested that differences in the magnitude and duration of shedding could be explained by the effect of the two helminths on the relative contribution of neutrophils and specific IgA and IgG to B. bronchiseptica neutralization in the respiratory tract. However, the interactions between infection and immune response at the scale of analysis that we used could not capture the rapid variation in the intensity of shedding of every rabbit. We suggest that fast and local changes at the level of respiratory tissue probably played a more important role. This study indicates that co-infected hosts are important source of variation in shedding, and provides a quantitative explanation into the role of helminths to the dynamics of respiratory bacterial infections.

Store expensiveness and consumer saving: Insights from a new decomposition of price dispersion

We build on recent work that analyzes consumers’ ability to save by exploiting price dispersion in grocery stores. We show that store expensiveness varies across consumers depending on the basket they consume, meaning that consumers can save more by shopping at a store that is cheaper for their basket rather than at a store that is cheaper overall. We incorporate this insight into a new price variance decomposition that is a refinement of existing approaches. Our results show that the ability to buy products from the store where they are cheapest is much less important than previous work had found; rather, the ability to choose the cheapest stores for one’s basket is a more important source of variation in the prices consumers pay. Our approach also provides an informal test for competing theories modeling consumers as either shopping for products or shopping for categories, and finds support for both. We conclude that the idea of consumers choosing the right store for their basket has substantial traction and is a useful addition to our arsenal of models of consumer search behavior.

Yield of soybean genotypes identified through GGE biplot and path analysis.

Genotype × environment (G×E) interaction is an important source of variation in soybean yield, which can significantly influence selection in breeding programs. This study aimed to select superior soybean genotypes for performance and yield stability, from data from multi-environment trials (METs), through GGE biplot analysis that combines the main effects of the genotype (G) plus the genotype-by-environment (G×E) interaction. As well as, through path analysis, determine the direct and indirect influences of yield components on soybean grain yield, as a genotype selection strategy. Eight soybean genotypes from the breeding program of Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA) were evaluated in field trials using a randomized block experimental design, in an 8 x 8 factorial scheme with four replications in eight different environments of the Cerrado of Northeastern Brazil during two crop seasons. Phenotypic performance data were measured for the number of days to flowering (NDF), height of first pod insertion (HPI), final plant height (FPH), number of days to maturity (NDM), mass of 100 grains (M100) and grain yield (GY). The results revealed that the variance due to genotype, environment, and G×E interaction was highly significant (P < 0.001) for all traits. The ST820RR, BRS 333RR, BRS SambaíbaRR, M9144RR and M9056RR genotypes exhibited the greatest GY stability in the environments studied. However, only the BRS 333RR genotype, followed by the M9144RR, was able to combine good productive performance with high yield stability. The study also revealed that the HPI and the NDM are traits that should be prioritized in the selection of soybean genotypes due to the direct and indirect effects on the GY.

Effectiveness of genetic grouping with different strategies for estimation of genetic parameters in growth traits in Merino lambs

The effectiveness of genetic grouping in genetic evaluations for growth traits in Merino sheep was researched in this study. In the study, 17,537 lambs born to 48 rams and 7118 ewes in 30 flocks were evaluated in animal models using REML. A model without a genetic group (GG0) was used in the analysis, as well as a model with three different genetic groups (GG). Maternal genetic and common environmental effects are included in all models. However, the models with and without covariance between direct and maternal effect were used for each trait. The Akaike Information Criterion (AIC) was used to compare models, taking into account the accuracy and Pearson and Spearman correlations between 48 rams for breeding values. Direct heritability (hd2), maternal heritability (m2) and maternal common environmental effects (cm2) were generally found to be less than 0.10. The most important source of variation was found to be flock-year-season (FYS). It is worth bearing in mind that cFYS2 has a very high share of phenotypic variance in all models, ranging from 0.07 ± 0.01–0.43 ± 0.03. The fact that there is such a wide environmental difference between enterprises in the same region is a major issue for the improvement programme. It is necessary to intensify studies on the one hand for the expansion of small businesses and on the other hand for more modern animal husbandry to achieve this. AIC found that models based on GGs were better suited for all traits. Unlike AIC, the GG0 model had the highest accuracy for rams. The accuracy of the model (GG3), in which the mothers of animals whose father was unknown were also deleted and genetically grouped for both, was found to be lower for ADG and higher for WW. Furthermore, while the average accuracy for BW decreased to 0.60 in the other genetic group (GG1: lambs born in the same year in a flock and GG2: lambs born in a flock) models, it was found to be around 0.80 for ADG and above 0.80 for WW. According to research findings, it is possible to perform a genetic evaluation without losing data, especially in pedigrees with unknown fathers.

The Relationship between School Infrastructure and School Nutrition Program Participation and Policies in New York City.

School nutrition programs (SNP) provide much needed access to fruits, vegetables, and other healthy foods at low or no cost. Yet, the infrastructure of school kitchens and cafeteria vary across schools, potentially contributing to systematic barriers for SNP operation and equity. The purpose of this paper is to examine the association between school infrastructure and outcomes including meal participation, untraditional lunch periods, and having an open campus. Regression analyses were conducted using administrative data for 1804 schools and school nutrition manager survey data (n = 821) in New York City (NYC). Co-location was significantly associated with open campus status (OR = 2.84, CI: 1.11, 7.26) and high school breakfast participation (β = −0.056, p = 0.003). Overcrowding was associated with breakfast (elementary: β = −0.046, p = 0.03; middle: β = 0.051, p = 0.04; high: β = 0.042, p = 0.04) and lunch participation (elementary: β = −0.031, p = 0.01) and untraditional lunchtimes (elementary: OR = 2.47, CI: 1.05, 5.83). Higher enrollment to cafeteria capacity ratios was associated with breakfast (elementary: β = −0.025, p = 0.02) and lunch (elementary: β = −0.015, p = 0.001; high: β = 0.014, p = 0.02) participation and untraditional lunchtimes (middle: OR = 1.66, CI: 1.03, 2.68). Infrastructure characteristics are an important source of variation across NYC schools that may hinder the equity of school nutrition programs across the city.