Development and application of optimum sensitivity analysis of structures

The research focused on developing an algorithm applying optimum sensitivity analysis for multilevel optimization. The research efforts have been devoted to assisting NASA Langley's Interdisciplinary Research Office (IRO) in the development of a mature methodology for a multilevel approach to the design of complex (large and multidisciplinary) engineering systems. An effort was undertaken to identify promising multilevel optimization algorithms. In the current reporting period, the computer program generating baseline single level solutions was completed and tested out

Expression of Heterosis in Leaming and Midland Corn Belt Dent Populations

Successful maize (Zea mays 1.) breeding programs are based on specific heterotic patterns. The Iowa Stiff Stalk Synthetic x Lancaster Sure Crop heterotic pattern is widely exploited in U.S. maize breeding programs. Alternative U.S. heterotic patterns have been suggested, but they have received limited attention and improvement. The objectives of this study were to evaluate cultivar crosses between Leaming and Midland Yellow Dent cultivars before and after inbred progeny selection and to assess their potential as an alternative U.S. heterotic pattern. Grain yield had a midparent heterosis value of 4.9% before selection and 17.8% in the third cycle of selection. The increase of grain yield heterosis (12.9%) through selection was highly significant (P \u3c 0.01), and crosses between S1 generations showed an increased rate of inbreeding depression through selection. Grain moisture of the cross (20.1 %) was significantly (P \u3c 0.05) less than the Midland Yellow Dent (24.5%) cultivar but was not significantly greater than the Leaming (17.7%) cultivar. Root lodging strength was significantly improved through selection with 1.1 % root lodging of the cross after selection (midparent heterosis value of -73.2%). Intrapopulation recurrent selection was successful for increasing the heterotic expression between Leaming and Midland Yellow Dent maize cultivars. An interpopulation recurrent selection program between the improved selection cycles Leaming and Midland Yellow Dent seems desirable

Le croisement romanov et finnois sur l'aragonaise : résultats préliminaires d'engraissement et de reproduction

International audienc

Inheritance of Gray Leaf Spot Resistance in Corn

Gray leaf spot disease, caused by Cercospora zeae-maydis Tehon and Daniels, has become a significant disease in Iowa corn (Zea mays L.) production. Incidence of gray leaf spot has increased with the increased use of conservation tillage practices. The inheritance of resistance to gray leaf spot was studied via use of generation mean analyses for five crosses and via use of 100 S1 progenies developed from an F2 population. Experiments were conducted at two locations that included either natural or artificial inoculation with C. zeae-maydis spores. Additive and dominance effects were significant in nearly all instances. Heritability for gray leaf spot resistance among S1 progenies was 0.78. Because resistance seemed to be determined by additive genetic variation, it seems selection for greater resistance to gray leaf spot can be effective. In all instances, the level of gray leaf spot resistance in single-cross hybrids was improved, whether the single-cross hybrid was produced with either one or both parents having resistance. It seems single-cross hybrids will have adequate levels of resistance to gray leaf spot if at least one of the parents has resistance

Mindfulness mediates relations between anxiety with problematic smartphone use severity

A growing body of literature has demonstrated relations between mood- and anxiety-related psychopathology with problematic smartphone use (PSU) symptom severity. However, there has been little empirical inquiry of potential mediators of these relationships. The current study examined trait mindfulness and smartphone use expectancies as mediators of the relation between depression/anxiety and PSU severity in 352 undergraduate students. Participants completed an online survey that measured depression, anxiety, smartphone use expectancies, and PSU severity. Structural equation modeling demonstrated that trait mindfulness was inversely associated, and smartphone use expectancies were positively associated, with PSU severity. Trait mindfulness significantly mediated relations between anxiety and PSU severity. Results provide implications for understanding PSU within the context of theoretical models of PSU’s development, and highlight the role of mindfulness as an emotion regulation strategy and potential treatment for PS

Recurrent selection methods to improve germplasm in maize

Recurrent selection (RS) schemes were introduced to increase the frequency of favorable alleles for quantitatively inherited traits. The main goal of RS was to genetically improve germplasm resources for breeding programs. Data were summarized for 14 intra-population and eight inter-population maize (Zea mays L) RS programs conducted in 17 genetically broad-based populations. The intra-population programs included evaluation of half-sib and full-sib families, either S1 or S2 inbred progenies, and a combination of S1 and S2 inbred progenies. The inter- population reciprocal RS programs were restricted to either half-sib or full-sib family selection. Grain yield was the primary trait considered in selection, but selection indices that include grain moisture at harvest and resistance to root and stalk lodging also were considered in making the selections that were intermated to form the next cycle population. Approximately, 10 to 20 selections were intermated for each cycle. Estimates of the genetic variation among progenies tested ( ), interactions of progenies with environments ( ), and experimental error ( ) were obtained from the combined analyses of variance for each cycle of selection and then averaged across cycles for each selection program. From the estimates of the components of variance, estimates of heritability (h2) on a progeny mean basis , the genetic coefficient of variation among progenies tested relative to their mean, (GCV), selection differentials (D), predicted genetic gains ( ), and least significant differences (LSD) were calculated and averaged across cycles of selection. The average estimates of were largest for inbred progeny selection and smallest for half-sib family selection as expected. Averaged expected genetic gain across all intra-population selection programs was 3.17 q ha-1 yr-1 vs 2.32 q ha-1 yr-1 for inter-population reciprocal recurrent selection, or 2.64 q ha-1 yr-1 across all methods. On a per cycle and per year basis the differences among types of progeny were relatively small, ranging from (3.57 q ha-1 yr-1,1.78 q ha-1 cycle-1) for half-sib family selection to (9.62 q ha-1 yr-1, 3.21 q ha-1 yr-1) for S2 inbred progeny selection. Regression analyses of the square roots of with cycles of selection suggested that genetic variation was not reduced significantly with selection. Even though RS was used to determine the primary types of genetic effects that respond to selection and contribute the expression of heterosis and could ideally support basic association and genome selection studies, the principle goal of RS is to adapt and improve genetically broad-based germplasm sources for potential use in breeding programs. Few programs have integrated RS programs with development programs to isolate unique inbred lines that have potential either as parents of hybrids or use in elite line crosses to develop recycled lines. In the past 10 years North Dakota has released 18 (out of 28) derived from RS programs, six from the NDSU EarlyGEM program (also diverse), and four from elite x elite combinations. Based on the number of progenies evaluated (25,692) in the RS programs presented and the number of inbred lines (31) that met standards for a ‘B’ designation and release to other maize breeders, the frequency of released lines was 0.12% or 1.2 lines per 1000 tested. However, the value of each line is different. B73 is a successful example of integrating recurrent and pedigree selection programs in order to develop outstanding cultivars. These significant gains can be realized with long-term RS selection programs. National support for them is encouraged in order to develop the next generation of maize products

Genetic Variation Among and Within S1 Progenies of Maize

Inbred line development consumes a great portion of the breeder\u27s time and resources in maize (Zea mays L.) breeding programs. Source populations for line development often are developed by selfing F2 populations developed from elite line crosses. Visual selection is practiced among and within selfed progenies during the selection process for one or two generations before evaluated in testcrosses for combining ability. Effective discrimination among and within inbred and testcross progenies depends on the amount of genetic variation present. The objective of this study was to determine the effectiveness of selection among and within S1 progenies developed from crosses of related and unrelated lines. Estimates of among-progeny variance were significant and, in all instances, larger than the estimate of within-progeny variance. Additive genetic variance accounted for the genetic variation among progenies of related and unrelated line crosses. Estimates of variability among and within S1 progeny testcrosses were not different from each other and were less than among and within S1 progenies themselves. In this study, it seems that the choice of testers was not appropriate to distinguish combining ability among progenies for both types of crosses, within the precision of this experiment. On the average, 70.7% greater genetic gains would be realized with among S1 progeny selection vs. within S1 progeny selection

Evaluation of Iowa Stiff Stalk Synthetic for resistance to gray leaf spot

Gray leaf spot (GLS) of maize (Zeamays), caused by Cercospora zeae-maydis, has become an increasing disease problem in the United States. Resistance to this pathogen is generally higher in inbred lines of Lancaster origin compared to lines derived from Iowa Stiff Stalk Synthetic (BSSS). This study was conducted to determine whether recurrent selection for yield had altered the level of GLS resistance in BSSS and to identify BSSS(R)Cl 1 S1 lines that combine GLS resistance with high yield. The distribution of GLS ratings for S1 lines derived from BSSSCO and BSSS(R)CI I were very similar, indicating that selection for yield had not altered G LS resistance· levels. Although the mean rating for both cycles was a susceptible 7 (I= resistant, 9 =susceptible), S1 lines with intermediate levels of resistance (4-6) were identified. The 250 BSSS(R)Cl I S1 lines were crossed to LH51, and the testcrosses were evaluated for yield and agronomic performance. S1 lines were identified which combine intermediate levels of GLS resistance with above-average standability and yield. These S1 lines will be recombined to develop an Iowa Stiff Stalk Synthetic population adapted to eastern maize growing conditions