Tight Subdesigns of the Higman-Sims Design

The Higman-Sims design is an incidence structure of 176 points and 176 blocks of cardinality 50 with every two blocks meeting in 14 points. The automorphism group of this design is the Higman-Sims simple group. We demonstrate that the point set and the block set of the Higman-Sims design can be partitioned into subsets X1, X2,...,X11 and B1, B2,...,B11, respectively, so that the substructures (Xi, Bi), i = 1, 2,...,11, are isomorphic symmetric (16, 6, 2)-designs

Examining Share Lease Arrangements for Grain Operations in the Texas Panhandle Under Changing Market Conditions

This paper examines the preferred share arrangement for both landlords and tenants producing grain in the Texas High Plains (based on risk preference), and determines the sensitivity to changing input costs and market prices. Results of the analyses show that tenants and landlords prefer different arrangements in all scenarios. Results also indicate that a tenant would prefer a different lease arrangement in 2008 than in 2005, while the landlord’s preference would remain unchanged.Financial Economics, Production Economics,

Pooled DNA sequencing to identify SNPs associated with a major QTL for bacterial wilt resistance in Italian ryegrass (Lolium multiflorum Lam.)

peer-reviewedItalian ryegrass (Lolium multiflorum Lam.) is one of the most important forage grass species in temperate regions. Its yield, quality and persistency can significantly be reduced by bacterial wilt, a serious disease caused by Xanthomonas translucens pv. graminis. Although a major QTL for bacterial wilt resistance has previously been reported, detailed knowledge on underlying genes and DNA markers to allow for efficient resistance breeding strategies is currently not available. We used pooled DNA sequencing to characterize a major QTL for bacterial wilt resistance of Italian ryegrass and to develop inexpensive sequence-based markers to efficiently target resistance alleles for marker-assisted recurrent selection. From the mapping population segregating for the QTL, DNA of 44 of the most resistant and 44 of the most susceptible F1 individuals was pooled and sequenced using the Illumina HiSeq 2000 platform. Allele frequencies of 18 × 106 single nucleotide polymorphisms (SNP) were determined in the resistant and susceptible pool. A total of 271 SNPs on 140 scaffold sequences of the reference parental genome showed significantly different allele frequencies in both pools. We converted 44 selected SNPs to KASP™ markers, genetically mapped these proximal to the major QTL and thus validated their association with bacterial wilt resistance. This study highlights the power of pooled DNA sequencing to efficiently target binary traits in biparental mapping populations. It delivers genome sequence data, SNP markers and potential candidate genes which will allow to implement marker-assisted strategies to fix bacterial wilt resistance in outcrossing breeding populations of Italian ryegrass

High-Intensity Radiated Field Fault-Injection Experiment for a Fault-Tolerant Distributed Communication System

Safety-critical distributed flight control systems require robustness in the presence of faults. In general, these systems consist of a number of input/output (I/O) and computation nodes interacting through a fault-tolerant data communication system. The communication system transfers sensor data and control commands and can handle most faults under typical operating conditions. However, the performance of the closed-loop system can be adversely affected as a result of operating in harsh environments. In particular, High-Intensity Radiated Field (HIRF) environments have the potential to cause random fault manifestations in individual avionic components and to generate simultaneous system-wide communication faults that overwhelm existing fault management mechanisms. This paper presents the design of an experiment conducted at the NASA Langley Research Center's HIRF Laboratory to statistically characterize the faults that a HIRF environment can trigger on a single node of a distributed flight control system

Prospective relationships between body weight and physical activity: an observational analysis from the NAVIGATOR study

Objectives: While bidirectional relationships exist between body weight and physical activity, direction of causality remains uncertain and previous studies have been limited by self-reported activity or weight and small sample size. We investigated the prospective relationships between weight and physical activity. Design: Observational analysis of data from the Nateglinide And Valsartan in Impaired Glucose Tolerance Outcomes Research (NAVIGATOR) study, a double-blinded randomised clinical trial of nateglinide and valsartan, respectively. Setting Multinational study of 9306 participants. Participants: Participants with biochemically confirmed impaired glucose tolerance had annual measurements of both weight and step count using research grade pedometers, worn for 7 days consecutively. Along with randomisation to valsartan or placebo plus nateglinide or placebo, participants took part in a lifestyle modification programme. Outcome measures: Longitudinal regression using weight as response value and physical activity as predictor value was conducted, adjusted for baseline covariates. Analysis was then repeated with physical activity as response value and weight as predictor value. Only participants with a response value preceded by at least three annual response values were included. Results: Adequate data were available for 2811 (30%) of NAVIGATOR participants. Previous weight (χ2=16.8; p<0.0001), but not change in weight (χ2=0.1; p=0.71) was inversely associated with subsequent step count, indicating lower subsequent levels of physical activity in heavier individuals. Change in step count (χ2=5.9; p=0.02) but not previous step count (χ2=0.9; p=0.34) was inversely associated with subsequent weight. However, in the context of trajectories already established for weight (χ2 for previous weight measurements 747.3; p<0.0001) and physical activity (χ2 for previous step count 432.6; p<0.0001), these effects were of limited clinical importance. Conclusions: While a prospective bidirectional relationship was observed between weight and physical activity, the magnitude of any effect was very small in the context of natural trajectories already established for these variables

Inelastic Neutron Scattering Cross Section Measurements for \u3csup\u3e134,136\u3c/sup\u3eXe of Relevance to Neutrinoless Double-\u3cem\u3eβ\u3c/em\u3e Decay Searches

Neutrinoless double-β decay (0νββ) searches typically involve large-scale experiments for which backgrounds can be complex. One possible source of background near the 0νββ signature in the observed spectra is γ rays arising from inelastic neutron scattering from the materials composing or surrounding the detector. In relation to searches for the 0νββ of 136Xe to 136Ba, such as the EXO-200 and KamLAND-Zen projects, inelastic neutron scattering γ-ray production cross sections for 136Xe and 134Xe are of importance for characterizing such γ rays that may inhibit the unambiguous identification of this yet-to-be-observed process. These cross sections have been measured at the University of Kentucky Accelerator Laboratory at neutron energies from 2.5 to 4.5 MeV

Orthology guided transcriptome assembly of Italian ryegrass and meadow fescue for single-nucleotide polymorphism discovery

Single-nucleotide polymorphisms (SNPs) represent natural DNA sequence variation. They can be used for various applications including the construction of high-density genetic maps, analysis of genetic variability, genome-wide association studies, and mapbased cloning. Here we report on transcriptome sequencing in the two forage grasses, meadow fescue (Festuca pratensis Huds.) and Italian ryegrass (Lolium multiflorum Lam.), and identification of various classes of SNPs. Using the Orthology Guided Assembly (OGA) strategy, we assembled and annotated a total of 18,952 and 19,036 transcripts for Italian ryegrass and meadow fescue, respectively. In addition, we used transcriptome sequence data of perennial ryegrass (L. perenne L.) from a previous study to identify 16,613 transcripts shared across all three species. Large numbers of intraspecific SNPs were identified in all three species: 248,000 in meadow fescue, 715,000 in Italian ryegrass, and 529,000 in perennial ryegrass. Moreover, we identified almost 25,000 interspecific SNPs located in 5343 genes that can distinguish meadow fescue from Italian ryegrass and 15,000 SNPs located in 3976 genes that discriminate meadow fescue from both Lolium species. All identified SNPs were positioned in silico on the seven linkage groups (LGs) of L. perenne using the GenomeZipper approach. With the identification and positioning of interspecific SNPs, our study provides a valuable resource for the grass research and breeding community and will enable detailed characterization of genomic composition and gene expression analysis in prospective Festuca Lolium hybrids

A novel multivariate approach to phenotyping and association mapping of multi-locus gametophytic self-incompatibility reveals S, Z and other loci in a perennial ryegrass (Poaceae) population

Self-incompatibility (SI) is a mechanism that many flowering plants employ to preventfertilisation by self- and self-like pollen ensuring heterozygosity and hybrid vigour.Although a number of single locus mechanisms have been characterised in detail, nomulti-locus systems have been fully elucidated. Historically, examples of the geneticanalysis of multi-locus SI, to make analysis tractable, are either made on the progenyof bi-parental crosses, where the number of alleles at each locus is restricted, or oncrosses prepared in such a way that only one of the SI loci segregates. Perennial ryegrass(Lolium perenne L.) possesses a well-documented two locus (S and Z) gametophyticincompatibility system. A more universal, realistic proof of principle study was conductedin a perennial ryegrass population in which allelic and non-allelic diversity was notartificially restricted. A complex pattern of pollinations from a diallel cross was revealedwhich could not possibly be interpreted easily per se, even with an already establishedgenetic model. Instead, pollination scores were distilled into principal component scoresdescribed as Compatibility Components (CC1-CC3). These were then subjected toa conventional genome-wide association analysis. CC1 associated with markers onlinkage groups (LGs) 1, 2, 3, and 6, CC2 exclusively with markers in a genomic regionon LG 2, and CC3 with markers on LG 1. BLAST alignment with the Brachypodiumphysical map revealed highly significantly associated markers with peak associationswith genes adjacent and four genes away from the chromosomal locations of candidateSI genes, S- and Z-DUF247, respectively. Further significant associations were found in aBrachypodium distachyon chromosome 3 region, having shared synteny with Lolium LG1, suggesting further SI loci linked to S or extensive micro-re-arrangement of the genomebetween B. distachyon and L. perenne. Significant associations with gene sequencesaligning with marker sequences on Lolium LGs 3 and 6 were also identified. We thereforedemonstrate the power of a novel association genetics approach to identify the genescontrolling multi-locus gametophytic SI systems and to identify novel loci potentiallyinvolved in already established SI systems.publishersversionPeer reviewe