Characterization of a microwave frequency resonator via a nearby quantum dot

We present measurements of a hybrid system consisting of a microwave transmission-line resonator and a lateral quantum dot defined on a GaAs heterostructure. The two subsystems are separately characterized and their interaction is studied by monitoring the electrical conductance through the quantum dot. The presence of a strong microwave field in the resonator is found to reduce the resonant conductance through the quantum dot, and is attributed to electron heating and modulation of the dot potential. We use this interaction to demonstrate a measurement of the resonator transmission spectrum using the quantum dot.Comment: 3 pages, 3 figure

Cytoplasmic Effect on Groat Protein Content in lnterspecific Matings of Avena sativa L. and A. sterilis L.

Thirty sets of reciprocal isopopulations, each with 20 Fi-derived oat lines from the BC0, BC1, and BC2 of all possible matings among five Awia slerilis L. accessions and two A. saliva cultivars, were evaluated in a replicated field trial to determine whether groat protein content was influenced by cytoplasmic inheritance and to study associations between protein content and agronomic traits. A. slerili cytoplasm had no direct effect on groat protein content, but significant interactions between the cytoplasms and nuclear genes from A. saliva and A. s1erilis were detected. Thus, the potential may exist for improving groat protein content of cultivated oats by exploiting specific intra and interspecific nucleo-cytoplasmic combinations. Generally, associations of various traits with groat protein content showed no trend for change over successive backcrosses, but phenotypic and genotypic correlations between protein percentage and all traits except harvest index tended to be larger for lines with A. s1erilis cytoplasm than those with A. saliva cytoplasm

Scaling and universality in coupled driven diffusive models

Inspired by the physics of magnetohydrodynamics (MHD) a simplified coupled Burgers-like model in one dimension (1d), a generalization of the Burgers model to coupled degrees of freedom, is proposed to describe 1dMHD. In addition to MHD, this model serves as a 1d reduced model for driven binary fluid mixtures. Here we have performed a comprehensive study of the universal properties of the generalized d-dimensional version of the reduced model. We employ both analytical and numerical approaches. In particular, we determine the scaling exponents and the amplitude-ratios of the relevant two-point time-dependent correlation functions in the model. We demonstrate that these quantities vary continuously with the amplitude of the noise cross-correlation. Further our numerical studies corroborate the continuous dependence of long wavelength and long time-scale physics of the model on the amplitude of the noise cross-correlations, as found in our analytical studies. We construct and simulate lattice-gas models of coupled degrees of freedom in 1d, belonging to the universality class of our coupled Burgers-like model, which display similar behavior. We use a variety of numerical (Monte-Carlo and Pseudospectral methods) and analytical (Dynamic Renormalization Group, Self-Consistent Mode-Coupling Theory and Functional Renormalization Group) approaches for our work. The results from our different approaches complement one another. Possible realizations of our results in various nonequilibrium models are discussed.Comment: To appear in JSTAT (2009); 52 pages in JSTAT format. Some figure files have been replace

Disruptive and Nondisruptive Selection for Bulk Oat Populations

A mixture of F3 seeds from 75 oat crosses was divided into four lots, with one being propagated in central Iowa for nine generations (i.e., stationary line of descent) and three being propagated in a rotational pattern in central, southern, and northern Iowa in successive generations (i.e., disruptively selected line of descent). An evaluation experiment was conducted to test whether any changes in genotypic frequencies were caused by the two propagation procedures. Increases in the means of yield traits occurred, but the magnitude and timing of the changes varied among lines of descent. The changes in the stationary and rotational lines of descent were indistinguishable. There was some trend for reduced genotypic variances for most traits with advancing generations. Probably the disruptive selection scheme did not cause differential results from the stationary one because the selection pressure due to differences in propagation sites was mild relative to the pressure due to differences in weather patterns during the years of the propagation period

Relationship between Groat-Oil Content and Grain Yield of Oats (Avena sativa L.)

Raising the energy content of oat (Avena sativa L.) groats by increasing their oil percentage could improve the economic value of oats as a feed grain and as a source of culinary oil. Relative importance of genotype x environment interaction for groat-oil content and grain yield and the correlations of groat-oil content with yield and maturity were evaluated for ten cultivars grown at three Iowa locations for two years. Cultivar x location mean squares were significant for both traits, but they were much smaller, relative to cultivar mean squares, for groat-oil content than for grain yield. Ranking of oat cultivars for groat-oil content was similar in all environments. Groat-oil content was positively correlated with grain yield in both years (r = 0.62* and 0.63*) and had a negative but nonsignificant correlation coefficient with maturity (r = - 0.28 and - 0.48). These relationships are favorable for the development of high-yielding, high groat-oil content cultivars

Yield Losses from Atypical Oat Blast in Central Iowa in 1957

An epiphytotic of blast occurred in the Iowa oat crop in 1957. The blasting was atypical in that the panicles were stratified with all of the spikelets in a section being blasted. Normally blasting occurs in the spikelets near the base of the panicle and the central axis. The environmental condition which appeared to be the most likely cause of the blasting was a cold, cloudy period between May 10 and 27. This was during early spikelet development and panicle elongation. Severity of atypical blasting was associated with earliness and lateness in the oat varieties. The highest percentage of panicles with atypical blast and the highest percentage of blast on these panicles occurred in varieties which beaded on June 13 and 14. Seeds from heads with atypical blast were from 10 to 25 per cent heavier than those from normal heads. The yield losses caused by atypical blast ranged from 7 to 15 per cent depending upon the maturity of the varieties

Microrheology probes length scale dependent rheology

We exploit the power of microrheology to measure the viscoelasticity of entangled F-actin solutions at different length scales from 1 to 100 mu m over a wide frequency range. We compare the behavior of single probe-particle motion to that of the correlated motion of two particles. By varying the average length of the filaments, we identify fluctuations that dissipate diffusively over the filament length. These provide an important relaxation mechanism of the elasticity between 0.1 and 30 rad/sec

New Oat Varieties for 1964 - Bonkee and Neal

These new oat varieties are more resistant to stem rust and crown rust than other Cherokee types. Bonkee yields averaged as well as Cherokee, and Neal produced the highest yields in 1961-62 Iowa oat variety trials

Sialic acid transporter NanT participates in Tannerella forsythia biofilm formation and survival on epithelial cells

Tannerella forsythia is a periodontal pathogen implicated in periodontitis. This gram-negative pathogen depends on exogenous peptidoglycan amino sugar N-acetylmuramic acid (NAM) for growth. In the biofilm state the bacterium can utilize sialic acid (Neu5Ac) instead of NAM to sustain its growth. Thus, the sialic acid utilization system of the bacterium plays a critical role in the growth and survival of the organism in the absence of NAM. We sought the function of a T. forsythia gene annotated as nanT coding for an inner-membrane sugar transporter located on a sialic acid utilization genetic cluster. To determine the function of this putative sialic acid transporter, an isogenic nanT-deletion mutant generated by allelic replacement strategy was evaluated for biofilm formation on NAM or Neu5Ac, and survival on KB epithelial cells. Moreover, since T. forsythia forms synergistic biofilms with Fusobacterium nucleatum, co-biofilm formation activity in mixed culture and sialic acid uptake in culture were also assessed. The data showed that the nanT-inactivated mutant of T. forsythia was attenuated in its ability to uptake sialic acid. The mutant formed weaker biofilms compared to the wild-type strain in the presence of sialic acid and as co-biofilms with F. nucleatum. Moreover, compared to the wild-type T. forsythia nanT-inactivated mutant showed reduced survival when incubated on KB epithelial cells. Taken together, the data presented here demonstrate that NanT-mediated sialic transportation is essential for sialic acid utilization during biofilm growth and survival of the organism on epithelial cells and implies sialic acid might be key for its survival both in subgingival biofilms and during infection of human epithelial cells in vivo

Atmospheric nitrogen oxides (NO and NO2) at Dome C, East Antarctica, during the OPALE campaign

Mixing ratios of the atmospheric nitrogen oxides NO and NO2 were measured as part of the OPALE (Oxidant Production in Antarctic Lands & Export) campaign at Dome C, East Antarctica (75.1 degrees S, 123.3 degrees E, 3233 m), during December 2011 to January 2012. Profiles of NOx mixing ratios of the lower 100m of the atmosphere confirm that, in contrast to the South Pole, air chemistry at Dome C is strongly influenced by large diurnal cycles in solar irradiance and a sudden collapse of the atmospheric boundary layer in the early evening. Depth profiles of mixing ratios in firn air suggest that the upper snowpack at Dome C holds a significant reservoir of photolytically produced NO2 and is a sink of gas-phase ozone (O-3). First-time observations of bromine oxide (BrO) at Dome C show that mixing ratios of BrO near the ground are low, certainly less than 5 pptv, with higher levels in the free troposphere. Assuming steady state, observed mixing ratios of BrO and RO2 radicals are too low to explain the large NO2 : NO ratios found in ambient air, possibly indicating the existence of an unknown process contributing to the atmospheric chemistry of reactive nitrogen above the Antarctic Plateau. During 2011-2012, NOx mixing ratios and flux were larger than in 2009-2010, consistent with also larger surface O-3 mixing ratios resulting from increased net O-3 production. Large NOx mixing ratios at Dome C arise from a combination of continuous sunlight, shallow mixing height and significant NOx emissions by surface snow (F-NOx). During 23 December 2011-12 January 2012, median F-NOx was twice that during the same period in 20092010 due to significantly larger atmospheric turbulence and a slightly stronger snowpack source. A tripling of F-NOx in December 2011 was largely due to changes in snowpack source strength caused primarily by changes in NO3- concentrations in the snow skin layer, and only to a secondary order by decrease of total column O-3 and associated increase in NO3- photolysis rates. A source of uncertainty in model estimates of F-NOx is the quantum yield of NO3- photolysis in natural snow, which may change over time as the snow ages