Some investigations of refractory metal systems of thermionic interest

Investigating interdiffusion of W-Ta, W-Mo, and W-Nb systems in refractory temperature rang

Thermodynamic description of a dynamical glassy transition

For the dynamical glassy transition in the $p$-spin mean field spin glass model a thermodynamic description is given. The often considered marginal states are not the relevant ones for this purpose. This leads to consider a cooling experiment on exponential timescales, where lower states are accessed. The very slow configurational modes are at quasi-equilibrium at an effective temperature. A system independent law is derived that expresses their contribution to the specific heat. $t/t_w$-scaling in the aging regime of two-time quantities is explained.Comment: 5 pages revte

The WARPS survey - IV: The X-ray luminosity-temperature relation of high redshift galaxy clusters

We present a measurement of the cluster X-ray luminosity-temperature relation out to high redshift (z~0.8). Combined ROSAT PSPC spectra of 91 galaxy clusters detected in the Wide Angle ROSAT Pointed Survey (WARPS) are simultaneously fit in redshift and luminosity bins. The resulting temperature and luminosity measurements of these bins, which occupy a region of the high redshift L-T relation not previously sampled, are compared to existing measurements at low redshift in order to constrain the evolution of the L-T relation. We find a best fit to low redshift (z1 keV, to be L proportional to T^(3.15\pm0.06). Our data are consistent with no evolution in the normalisation of the L-T relation up to z~0.8. Combining our results with ASCA measurements taken from the literature, we find eta=0.19\pm0.38 (for Omega_0=1, with 1 sigma errors) where L_Bol is proportional to (1 + z)^eta T^3.15, or eta=0.60\pm0.38 for Omega_0=0.3. This lack of evolution is considered in terms of the entropy-driven evolution of clusters. Further implications for cosmological constraints are also discussed.Comment: 11 pages, 7 figures, accepted for publication in MNRA

Studies of thermionic materials for space power applications informal monthly report, sep. 1 - sep. 30, 1963

Thermionic materials for space power application - uranium carbide-zirconium carbide fuels and tungsten claddin

The planets around NN Serpentis : still there

We present 25 new eclipse times of the white dwarf binary NN Ser taken with the high-speed camera ULTRACAM on the William Herschel Telescope and New Technology Telescope, the RISE camera on the Liverpool Telescope and HAWK-I on the Very Large Telescope to test the two-planet model proposed to explain variations in its eclipse times measured over the last 25 yr. The planetary model survives the test with flying colours, correctly predicting a progressive lag in eclipse times of 36 s that has set in since 2010 compared to the previous 8 yr of precise times. Allowing both orbits to be eccentric, we find orbital periods of 7.9 ± 0.5 and 15.3 ± 0.3 yr, and masses of 2.3 ± 0.5 and 7.3 ± 0.3 MJ. We also find dynamically long-lived orbits consistent with the data, associated with 2:1 and 5:2 period ratios. The data scatter by 0.07 s relative to the best-fitting model, by some margin the most precise of any of the proposed eclipsing compact object planet hosts. Despite the high precision, degeneracy in the orbit fits prevents a significant measurement of a period change of the binary and of N-body effects. Finally, we point out a major flaw with a previous dynamical stability analysis of NN Ser, and by extension, with a number of analyses of similar systems

Seed-set evaluation of four male-sterile, female-fertile soybean lines using alfalfa leafcutting bees and honey bees as pollinators

Male-sterile, female-fertile plants were used to produce hybrid soybean seed. Manual cross-pollination using male-sterile plants to produce large quantities of hybrid seed is difficult and time-consuming because of the low success rate in cross-pollination. Insect pollinators may be suitable vectors to transfer pollen, but the most suitable vector for pollen transfer from the male parent to the female parent has not been identified for soybean. The objective of the present study was to evaluate seed-set on four male-sterile, female-fertile soybean lines by using alfalfa leafcutting bees (Megachile rotundata (F.)) and honey bees (Apis mellifera (L.)) as pollinators. Seed-set was evaluated in summers 2003 and 2005 near Ames, Iowa, USA and in summers 2003, 2004, and 2005 near Wooster, Ohio, USA. Neither the effect of pollinator species nor the interaction effect of pollinator species×location was significant for any year. Honey bees performed similarly to alfalfa leafcutting bees at both locations. The results indicated significant differences for seed-set among male-sterile lines, suggesting preferential pollination. Male-sterile lines, ms1(Urbana) and ms2 (Ames 2), had higher cross-pollinated seed-set compared to ms6 (Ames 1), and ms6 (Corsoy 79). At the Ames location, ms1ms1 (Urbana) plants had the highest seed-set (50·16 seeds per male-sterile plant in 2005). At the Wooster location, ms1ms1 (Urbana) plants also had the highest seed-set (92·04 seeds per male-sterile plant) in 2005. Costs and local conditions need to be addressed to support the choice of either pollinator species as a pollination vector to produce hybrid soybean seed

The Plant NF-Y DNA Matrix In Vitro and In Vivo

Nuclear Factor Y (NF-Y) is an evolutionarily conserved trimer formed by a Histone-Fold Domain (HFD) heterodimeric module shared by core histones, and the sequence-specific NF-YA subunit. In plants, the genes encoding each of the three subunits have expanded in number, giving rise to hundreds of potential trimers. While in mammals NF-Y binds a well-characterized motif, with a defined matrix centered on the CCAAT box, the specificity of the plant trimers has yet to be determined. Here we report that Arabidopsis thaliana NF-Y trimeric complexes, containing two different NF-YA subunits, bind DNA in vitro with similar affinities. We assayed precisely sequence-specificity by saturation mutagenesis, and analyzed genomic DNA sites bound in vivo by selected HFDs. The plant NF-Y CCAAT matrix is different in nucleotides flanking CCAAT with respect to the mammalian matrix, in vitro and in vivo. Our data point to flexible DNA-binding rules by plant NF-Ys, serving the scope of adapting to a diverse audience of genomic motifs