Heterosis between semidormant and nondormant derived alfalfa germplasm

Alfalfa (Medicago sativa L.) yield has not increased over the past 25 years in the Midwestern United States. One way to increase yield in alfalfa is through capturing heterosis. Heterotic groups are genetically distinct germplasms that, when hybridized, repeatedly produce progeny that express heterosis. In alfalfa, three main heterotic groups have been proposed in the United States: dormant M. falcata, semidormant M. sativa, and nondormant M. sativa. Nondormant alfalfa cannot be used in the upper Midwestern United States due to severe winterkill. Three cycles of recurrent selection were conducted in four nondormant cultivars and winter hardiness was substantially improved in all four. The objective of this study was to test the hypothesis that the nondormant derived alfalfa germplasm represents a heterotic group distinct from Midwestern United States cultivars. Four elite Midwestern alfalfa cultivars and the four nondormant derived populations were hand crossed in a half diallel mating design. A seeded trial was established at one Iowa location in 2003 and transplanted trials grown at two locations at 2004. In spite of the observation of better yield in some of the particular crosses, a general heterotic pattern was not observed between the two proposed groups

Microscopic theory of the activated behavior of the quantized Hall effect

The thermally activated behavior of the gate defined narrow Hall bars is studied by analyzing the existence of the incompressible strips within a Hartree-type approximation. We perform self-consistent calculations considering the linear response regime, supported by a local conductivity model. We investigate the variation of the activation energy depending on the width of samples in the range of $2d\sim [1-10] \mu m$. We show that the largest activation energy of high-mobility narrow samples, is at the low field edge of Hall filling factor 2 plateau (exceeding half of the cyclotron energy), whereas for relatively wide samples the higher activation energy is obtained at the high field edge of Hall plateau. In contrast to the single-particle theories based on the localization of electronic states, we found that the activation energy is almost independent of the properties of the density of states.Comment: 8 pages, 4 figure

Electronic band structure of GaAs/AlxGa1−xAs superlattice in an intense laser field

ABSTRACT: We perform theoretical calculations for the band structure of semiconductor superlattice under intense high-frequency laser field. In the frame of the non-perturbative approach, the laser effects are included via laser-dressed potential. Results reveal that an intense laser field creates an additional geometric confinement on the electronic states. Numerical results show that when tuning the strength of the laser field significant changes come in the electronic energy levels and density of states

The effect of magnetic field on the impurity binding energy of shallow donor impurities in a Ga1−xInxNyAs1−y/GaAs quantum well

ABSTRACT: Using a variational approach, we have investigated the effects of the magnetic field, the impurity position, and the nitrogen and indium concentrations on impurity binding energy in a Ga1−xInxNyAs1−y/GaAs quantum well. Our calculations have revealed the dependence of impurity binding on the applied magnetic field, the impurity position, and the nitrogen and indium concentrations

Identification of genetic basis of agronomic traits in alfalfa (Medicago sativa subsp. sativa) using Genome Wide Association Studies

Alfalfa (Medicago sativa L.) is one of the most widely cultivated forage crops due to its high yield, value of nutrients, and adaptation to diverse environments. However, many of the desired agronomic traits in alfalfa are quantitative, and therefore improving them under abiotic and biotic stresses becomes an important goal in alfalfa breeding. One way to achieve such a goal is identification of loci that contribute to variation in complex traits. Genome Wide Association Studies (GWAS) provide advanced tools to identify genetic loci associated with traits of interest using high-density markers throughout the genome. In M. sativa, previous studies indicated that GWAS could identify numerous candidate single nucleotide polymorphism (SNP) markers for quantitative traits, including biomass, yield, forage quality, and drought/salt tolerance. Furthermore, mapping SNP markers against the M. sativa reference genome revealed many putative candidate genes which are associated with several cell wall-related traits. In this review, we summarize Genome Wide Association (GWAS) in alfalfa from concept to application and the identification and characterization of candidate genes for traits of interest

Interaction mediated asymmetries of the quantized Hall effect

Experimental and theoretical investigations on the integer quantized Hall effect in gate defined narrow Hall bars are presented. At low electron mobility the classical (high temperature) Hall resistance line RH(B) cuts through the center of all Hall plateaus. In contrast, for our high mobility samples the intersection point, at even filling factors \nu = 2; 4 ..., is clearly shifted towards larger magnetic fields B. This asymmetry is in good agreement with predictions of the screening theory, i. e. taking Coulomb interaction into account. The observed effect is directly related to the formation of incompressible strips in the Hall bar. The spin-split plateau at \nu= 1 is found to be almost symmetric regardless of the mobility. We explain this within the so-called effective g-model.Comment: 4 pages, 3 figure

Theoretical investigation of InAs/GaSb type-II pin superlattice infrared detector in the mid wavelength infrared range

In this study, we present the theoretical investigation of type-II InAs/GaSb superlattice p-i-n detector. Kronig-Penney and envelope function approximation is used to calculate band gap energy and superlattice minibands. Variational method is also used to calculate exciton binding energies. Our results show that carriers overlap increases at GaSb/InAs interface on the higher energy side while it decreases at InAs/GaSb interface on the lower energy side with increasing reverse bias due to shifting the hole wavefunction toward to the GaSb/InAs interface decisively. Binding energies increase with increasing electric field due to overall overlap of electron and hole wave functions at the both interfaces in contrast with type I superlattices. This predicts that optical absorption is enhanced with increasing electric field. © 2013 American Institute of Physics

Annual and perennial Medicago show signatures of parallel adaptation to climate and soil in highly conserved genes

Human induced environmental change may require rapid adaptation of plant populations and crops, but the genomic basis of environmental adaptation remain poorly understood. We analysed polymorphic loci from the perennial crop Medicago sativa (alfalfa or lucerne) and the annual legume model species M. truncatula to search for a common set of candidate genes that might contribute to adaptation to abiotic stress in both annual and perennial Medicago species. We identified a set of candidate genes of adaptation associated with environmental gradients along the distribution of the two Medicago species. Candidate genes for each species were detected in homologous genomic linkage blocks using genome-environment (GEA) and genome-phenotype association analyses. Hundreds of GEA candidate genes were species-specific, of these, 13.4% (M. sativa) and 24% (M. truncatula) were also significantly associated with phenotypic traits. A set of 168 GEA candidates were shared by both species, which was 25.4% more than expected by chance. When combined, they explained a high proportion of variance for certain phenotypic traits associated with adaptation. Genes with highly conserved functions dominated among the shared candidates and were enriched in gene ontology terms that have shown to play a central role in drought avoidance and tolerance mechanisms by means of cellular shape modifications and other functions associated with cell homeostasis. Our results point to the existence of a molecular basis of adaptation to abiotic stress in Medicago determined by highly conserved genes and gene functions. We discuss these results in light of the recently proposed omnigenic model of complex traits

Süt ve süt ürünleri üretim zincirinde yer alan kisiler için online süt hijyeni egitim modülleri

Tilki, M., Topçu, B., Şakiroğlu, M., Gomes, A., Pintado, M., Öztürk, E., Emir, M., Aydın, E., Cebeci Aydın, A., Lopez Colmenero, E., Lopez, L., Maki, M. 2013. Maidon ja maitotuotteiden tuotantoketjun hygienian opetusmoduulit. TGDF Gıda Kongresi 2013, Antalya. Posteriabstraktit, s. 7