SNP-based genetic diversity among few-branched-1 (Fbr1) maize lines and its relationship with heterosis, combining ability and grain yield of testcross hybrids

Single nucleotide polymorphism (SNP) markers are regarded as efficient,compared to other marker types in genetic characterization of maize (Zea mays L.) germplasm because of their vast coverage of the maize genome. The objectives of this study were to (a) genetically fingerprint few-branched-1’ (Fbr1) and normal tasselled CIMMYT elite lines using SNP markers, to assess their relatedness and level of homozygosity and (b) to determine SNP-based genetic distance among these maize lines and to find association of genetic distances with specific combining ability (SCA), mid-parent heterosis (MPH), high-parent heterosis (HPH) and mean grain yield of the hybrids. Twenty-six CIMMYT maize lines (12 with the Fbr1 gene, and 14 normal-tasselled) were genotyped using 1074 SNP marker loci. Fifteen of these lines were used in two separate diallel mating designs: a 9x9 and 6x6 crossing set-up, to make hybrids for yield evaluation. Average residual heterozygosity of SNP loci ranged from 0.2-36.1%, with an average of 8.2%, well above the expected ranges for residual heterozygosity found in maize inbred lines. The polymorphic information content (PIC) for the 1074 SNP loci ranged from 0.015-0.50, with an average of 0.25. Mean genetic distance for all pair wise comparisons of lines was lower (0.30) suggesting a high level of relatedness among lines. A number of elite CIMMYT lines were successfully converted to Fbr1, and were homozygous for the 1074 SNP loci, thus could be used in breeding programmes involving these new tassel mutants. The unweighted paired group method using arithmetic averages (UPGMA) cluster analysis revealed two discrete clusters for the inbred lines, reflecting heterotic groups used by CIMMYT. In the principal component (PC) analysis, PC1 and PC2 explained 10.87 and 9.08% respectively, of the molecular variance in tassel size for the 1074 SNPs. The results confirmed molecular markers as a powerful complement for use in genetic characterization, in assigning lines into defined heterotic groups and in examining the relationships among inbred lines at deoxyribonucleic acid (DNA) level. Marker-based genetic distances were positively correlated with hybrid performance, SCA and heterosis indicating that they could accurately predict hybrid performance in this set of germplasm. Grain yield for the hybrids ranged from 0.49-2.48 kg/plot, with an average of 1.80 kg/plot. Hybrids from closely related parental lines (according to SNP-based genetic distances) had the lowest mean grain yield, lowest SCA effects for grain yield, and had the lowest heterosis values. Thus, SNP-based genetic distance information would be useful for effective selection by avoiding genetically similar lines when selecting parents for breeding programmes that require genetically diverse lines as parents

Renormalized Vacuum Polarization and Stress Tensor on the Horizon of a Schwarzschild Black Hole Threaded by a Cosmic String

We calculate the renormalized vacuum polarization and stress tensor for a massless, arbitrarily coupled scalar field in the Hartle-Hawking vacuum state on the horizon of a Schwarzschild black hole threaded by an infinte straight cosmic string. This calculation relies on a generalized Heine identity for non-integer Legendre functions which we derive without using specific properties of the Legendre functions themselves.Comment: This is an expanded version of a previous submission, we have added the calculation of the stress tensor. 28 pages, 7 figure

Conductance Phases in Aharonov-Bohm Ring Quantum Dots

The regimes of growing phases (for electron numbers N~0-8) that pass into regions of self-returning phases (for N>8), found recently in quantum dot conductances by the Weizmann group are accounted for by an elementary Green function formalism, appropriate to an equi-spaced ladder structure (with at least three rungs) of electronic levels in the quantum dot. The key features of the theory are physically a dissipation rate that increases linearly with the level number (and tentatively linked to coupling to longitudinal optical phonons) and a set of Fano-like meta-stable levels, which disturb the unitarity, and mathematically the change over of the position of the complex transmission amplitude-zeros from the upper-half in the complex gap-voltage plane to the lower half of that plane. The two regimes are identified with (respectively) the Blaschke-term and the Kramers-Kronig integral term in the theory of complex variables.Comment: 20 pages, 4 figure

Model-Independent Sum Rule Analysis Based on Limited-Range Spectral Data

Partial sum rules are widely used in physics to separate low- and high-energy degrees of freedom of complex dynamical systems. Their application, though, is challenged in practice by the always finite spectrometer bandwidth and is often performed using risky model-dependent extrapolations. We show that, given spectra of the real and imaginary parts of any causal frequency-dependent response function (for example, optical conductivity, magnetic susceptibility, acoustical impedance etc.) in a limited range, the sum-rule integral from zero to a certain cutoff frequency inside this range can be safely derived using only the Kramers-Kronig dispersion relations without any extra model assumptions. This implies that experimental techniques providing both active and reactive response components independently, such as spectroscopic ellipsometry in optics, allow an extrapolation-independent determination of spectral weight 'hidden' below the lowest accessible frequency.Comment: 5 pages, 3 figure

High temperature thermodynamics of strongly interacting s-wave and p-wave Fermi gases in a harmonic trap

We theoretically investigate the high-temperature thermodynamics of a strongly interacting trapped Fermi gas near either s-wave or p-wave Feshbach resonances, using a second order quantum virial expansion. The second virial coefficient is calculated based on the energy spectrum of two interacting fermions in a harmonic trap. We consider both isotropic and anisotropic harmonic potentials. For the two-fermion interaction, either s-wave or p-wave, we use a pseudopotential parametrized by a scattering length and an effective range. This turns out to be the simplest way of encoding the energy dependence of the low-energy scattering amplitude or phase shift. This treatment of the pseudopotential can be easily generalized to higher partial-wave interactions. We discuss how the second virial coefficient and thermodynamics are affected by the existence of these finite-range interaction effects. The virial expansion result for a strongly interacting s -wave Fermi gas has already been proved very useful. In the case of p-wave interactions, our results for the high-temperature equation of state are applicable to future high-precision thermodynamic measurements for a spin-polarized Fermi gas near a p-wave Feshbach resonance.Comment: 12 pages,10 figure

Analytical solutions for two atoms in a harmonic trap: p-wave interactions

We derive analytical solutions for the system of two ultracold spin-polarized fermions interacting in p wave and confined in an axially symmetric harmonic trap. To this end we utilize p-wave pseudopotential with an energy-dependent scattering volume. This allows to describe the scattering in tight trapping potentials in the presence of scattering resonances. We verify predictions of the pseudopotential treatment for some model interaction potential, obtaining an excellent agreement with exact energy levels. Then we turn to the experimentally relevant case of neutral atom interactions in the vicinity of a p-wave Feshbach resonance. In the framework of the multichannel quantum-defect theory we derive relatively simple formula for an energy-dependent scattering volume, and later we apply it to investigate the energy spectrum of trapped atoms close to the p-wave Feshbach resonance.Comment: 13 pages, 5 figure

Design of Bifunctional Dendritic 5-Aminolevulinic Acid and Hydroxypyridinone Conjugates for Photodynamic Therapy

Iron chelators have recently attracted interest in the field of photodynamic therapy (PDT) owing to their role in enhancement of intracellular protoporphyrin IX (PpIX) generation induced by 5-aminolevulinic acid (ALA) via the biosynthetic heme cycle. Although ALA is widely used in PDT, cellular uptake of ALA is limited by its hydrophilicity. In order to improve ALA delivery and enhance the PpIX production, several dendrimers incorporating both ALA and 3-hydroxy-4-pyridinone (HPO) were synthesized. The ability of the dendrimers to enter cells and be metabolized to the PpIX photosensitizer was studied in several human cancer cell lines. The dendrimers were found to be significantly more efficient than ALA alone in PpIX production. The higher intracellular PpIX levels showed a clear correlation with enhanced cellular phototoxicity following light exposure. Dendritic derivatives are therefore capable of efficiently delivering both ALA and HPO, which act synergistically to amplify in vitro PpIX levels and enhance PDT efficacy

Effects of bovine serum albumin on light activated antimicrobial surfaces

Bovine serum albumin (BSA) is currently recommended as an interfering substance to emulate organic soiling, in evaluating the efficacy of disinfectants. The European Standard recommends 0.03% BSA to test clean conditions and 0.3% for dirty conditions. Reactive oxygen species are known to exert excellent antimicrobial activity with low specificity against a broad range of pathogens. Herein, we present our data from the first study of the effects of the addition of BSA on the antibacterial activity of light activated antimicrobial surfaces. Light activated antimicrobial surfaces were made from polyurethane swell-encapsulated with gold nanoparticles (AuNPs) coated with the light active triarylmethane dye, crystal violet (PU-AuNP-CV). The antibacterial efficacy of the antimicrobial substrates was tested against two strains of Staphylococcus aureus 8325-4, a well-characterised laboratory strain and MRSA 4742, a recent clinical isolate, in the presence of 0.1% to 1% BSA by irradiating the substrates with a fluorescent lamp (300 lux). After 6 hours of irradiation, the number of surviving bacteria was determined. The results showed that BSA reduced the antibacterial efficacy of all the PU-AuNP-CV surfaces with increasing BSA concentrations resulting in a progressive reduction in antibacterial activity towards the bacteria tested. However, the light activated surfaces did perform well at 0.1 and 0.25% BSA levels, showing they may have potential for real world environments with low levels of organic soiling