Development and Validation of Molecular Markers for \u3cem\u3ePhytophthora medicaginis\u3c/em\u3e Resistance in Lucerne

Resistance to Phytophthora medicaginis is an essential attribute to incorporate into lucerne (Medicago sativa) cultivars which are likely to be grown on heavy soils or in conditions where the soil remains excessively wet for prolonged periods. Current breeding strategies rely on recurrent phenotypic selection to maintain adequate levels of resistance in newly developed synthetic cultivars. However, little is known about the source or mechanism(s) of genetic resistance operating in the cultivar. A genetic linkage map was generated from a tetraploid M. sativa population using SSR markers anchored to existing genetic and physical maps. Large effect QTL were identified on linkage groups 2, 5, 6 and 7, each of which contributed between 11-30% of the phenotypic variation. Evaluation of the marker-trait associations in another sampling of the same population was undertaken, using a different isolate of P. medicaginis. The findings indicate that in the lucerne genotype examined in this study, a network of interactions involving at least three common loci, contribute to resistance to P. medicaginis. An alignment of the resistance loci identified in this study with those previously identified provided a framework for cataloguing the diversity of resistance loci present in lucerne, and will be used to guide future lucerne breeding efforts

Excavations at the Bluff Creek Sites: 41MK10 and 41MK27, McColloch County, Texas

From late 1978 through early 1979, Ann M. Irwin of the Texas Department of Transportation (TxDOT) supervised excavations of two prehistoric archeological sites, 41MK10 and 41MK27, that were to be affected by construction along FM 765 in McCulloch County, Texas. The sites are located on Bluff Creek in the northern part of McCulloch County. Analyses of sites 41MK10 and 41MK27 and their cultural materials were conducted by TxDOT personnel in 1979, and an initial draft form of the report was prepared by Irwin in the early 1980s. TxDOT subsequently contracted SWCA, Inc. Environmental Consultants in 1999 to complete the report of the results of archeological investigations at 41MK10 and 41MK27 and to prepare the artifacts and records for curation. Site 41MK27 contained a small burned rock midden, Feature I. This midden was approximately 8 to 10 m in diameter, and 50 cm thick, and annular in form. A single internal feature (Feature IA), a rock-lined pit or hearth, was located in the approximate center and bottom of the midden. Lying between the midden and Bluff Creek were a series of small hearths, of which eight were excavated and designated as Features III through X. These small hearths, most of which had been at least somewhat disturbed, appeared to have been simple structures composed of one or more layers of rock. Many of the individual rocks appear to have been fire-fractured in place. No true basin-shaped hearths were observed. Associated with these hearths were an accompanying scatter of living debris in the form of flint and burned rock and significant quantities of freshwater mussel shell. Although the individual specimens are relatively small, the quantities recovered suggest that they served as a source of food. Radiocarbon data suggest that the site was intermittently occupied from the Late Archaic through the Late Prehistoric. The midden apparently dates to the Late Prehistoric, although the Transitional Archaic period may have been the period of most intense occupation at the site. Site 41MK10 was smaller than 41MK27 and not as intensively investigated. Two small burned rock features were excavated. The site was at least visited in the Late Archaic times, as is evidenced by the presence of a Castroville point, and in the Transitional Archaic, indicated by the recovery of two Ensor projectile points. It is likely, though by no means firmly established, that these dart point types are in fact associated with the use of the features

Pure dephasing in flux qubits due to flux noise with spectral density scaling as 1/fα1/ f^\alpha

For many types of superconducting qubits, magnetic flux noise is a source of pure dephasing. Measurements on a representative dc superconducting quantum interference device (SQUID) over a range of temperatures show that $S_\Phi(f) = A^2/(f/1 \hbox{Hz})^\alpha$, where $S_\Phi$ is the flux noise spectral density, $A$ is of the order of 1 $\mu\Phi_0 \, \hbox{Hz}^{-1/2}$ and $0.61 \leq \alpha \leq 0.95$; $\Phi_{0}$ is the flux quantum. For a qubit with an energy level splitting linearly coupled to the applied flux, calculations of the dependence of the pure dephasing time $\tau_\phi$ of Ramsey and echo pulse sequences on $\alpha$ for fixed $A$ show that $\tau_\phi$ decreases rapidly as $\alpha$ is reduced. We find that $\tau_\phi$ is relatively insensitive to the noise bandwidth, $f_1 \leq f \leq f_2$, for all $\alpha$ provided the ultraviolet cutoff frequency $f_2 > 1/\tau_\phi$. We calculate the ratio $\tau_{\phi,E} / \tau_{\phi,R}$ of the echo ($E$) and Ramsey ($R$) sequences, and the dependence of the decay function on $\alpha$ and $f_2$. We investigate the case in which $S_\Phi(f_0)$ is fixed at the "pivot frequency" $f_0 \neq 1$ Hz while $\alpha$ is varied, and find that the choice of $f_0$ can greatly influence the sensitivity of $\tau_{\phi,E}$ and $\tau_{\phi,R}$ to the value of $\alpha$. Finally, we present calculated values of $\tau_\phi$ in a qubit corresponding to the values of $A$ and $\alpha$ measured in our SQUID.Comment: 7 pages, 8 figures, 1 tabl

A Sample of Very Young Field L Dwarfs and Implications for the Brown Dwarf "Lithium Test" at Early Ages

Using a large sample of optical spectra of late-type dwarfs, we identify a subset of late-M through L field dwarfs that, because of the presence of low-gravity features in their spectra, are believed to be unusually young. From a combined sample of 303 field L dwarfs, we find observationally that 7.6+/-1.6% are younger than 100 Myr. This percentage is in agreement with theoretical predictions once observing biases are taken into account. We find that these young L dwarfs tend to fall in the southern hemisphere (Dec < 0 deg) and may be previously unrecognized, low-mass members of nearby, young associations like Tucana-Horologium, TW Hydrae, beta Pictoris, and AB Doradus. We use a homogeneously observed sample of roughly one hundred and fifty 6300-10000 Angstrom spectra of L and T dwarfs taken with the Low-Resolution Imaging Spectrometer at the W. M. Keck Observatory to examine the strength of the 6708-A Li I line as a function of spectral type and further corroborate the trends noted by Kirkpatrick et al. (2000). We use our low-gravity spectra to investigate the strength of the Li I line as a function of age. The data weakly suggest that for early- to mid-L dwarfs the line strength reaches a maximum for a few 100 Myr, whereas for much older (few Gyr) and much younger (<100 Myr) L dwarfs the line is weaker or undetectable. We show that a weakening of lithium at lower gravities is predicted by model atmosphere calculations, an effect partially corroborated by existing observational data. Larger samples containing L dwarfs of well determined ages are needed to further test this empirically. If verified, this result would reinforce the caveat first cited in Kirkpatrick et al. (2006) that the lithium test should be used with caution when attempting to confirm the substellar nature of the youngest brown dwarfs.Comment: 73 pages with 22 figures; to appear in ApJ (Dec 20, 2008, v689n2 issue

Low Temperature Opacities

Previous computations of low temperature Rosseland and Planck mean opacities from Alexander & Ferguson (1994) are updated and expanded. The new computations include a more complete equation of state with more grain species and updated optical constants. Grains are now explicitly included in thermal equilibrium in the equation of state calculation, which allows for a much wider range of grain compositions to be accurately included than was previously the case. The inclusion of high temperature condensates such as Al$_2$O$_3$ and CaTiO$_3$ significantly affects the total opacity over a narrow range of temperatures before the appearance of the first silicate grains. The new opacity tables are tabulated for temperatures ranging from 30000 K to 500 K with gas densities from 10$^{-4}$ g cm$^{-3}$ to 10$^{-19}$ g cm$^{-3}$. Comparisons with previous Rosseland mean opacity calculations are discussed. At high temperatures, the agreement with OPAL and Opacity Project is quite good. Comparisons at lower temperatures are more divergent as a result of differences in molecular and grain physics included in different calculations. The computation of Planck mean opacities performed with the opacity sampling method are shown to require a very large number of opacity sampling wavelength points; previously published results obtained with fewer wavelength points are shown to be significantly in error. Methods for requesting or obtaining the new tables are provided.Comment: 39 pages with 12 figures. To be published in ApJ, April 200

Evidence for dark energy from the cosmic microwave background alone using the Atacama Cosmology Telescope lensing measurements

For the first time, measurements of the cosmic microwave background radiation (CMB) alone favor cosmologies with $w=-1$ dark energy over models without dark energy at a 3.2-sigma level. We demonstrate this by combining the CMB lensing deflection power spectrum from the Atacama Cosmology Telescope with temperature and polarization power spectra from the Wilkinson Microwave Anisotropy Probe. The lensing data break the geometric degeneracy of different cosmological models with similar CMB temperature power spectra. Our CMB-only measurement of the dark energy density $\Omega_\Lambda$ confirms other measurements from supernovae, galaxy clusters and baryon acoustic oscillations, and demonstrates the power of CMB lensing as a new cosmological tool.Comment: 4 pages, 3 figures; replaced with version accepted by Physical Review Letters, added sentence on models with non-standard primordial power spectr

Assessing Change in Social Support During Late Life

The purpose of this study is to evaluate change in 14 measures of social support with data provided by a nationwide longitudinal study of older adults. The findings reveal that fairly substantial change took place during the three-year follow-up period. More important, the data indicate that change is not uniform or systematic across the entire study sample. Instead, there appears to be considerable individual-level change taking place. The implications of these findings for the development of conceptual models as well as support-based interventions are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68866/2/10.1177_0164027599214002.pd

Discovery of Human sORF-Encoded Polypeptides (SEPs) in Cell Lines and Tissue

The existence of nonannotated protein-coding human short open reading frames (sORFs) has been revealed through the direct detection of their sORF-encoded polypeptide (SEP) products. The discovery of novel SEPs increases the size of the genome and the proteome and provides insights into the molecular biology of mammalian cells, such as the prevalent usage of non-AUG start codons. Through modifications of the existing SEP-discovery workflow, we discover an additional 195 SEPs in K562 cells and extend this methodology to identify novel human SEPs in additional cell lines and human tissue for a final tally of 237 new SEPs. These results continue to expand the human genome and proteome and demonstrate that SEPs are a ubiquitous class of nonannotated polypeptides that require further investigation

Pointing control for the SPIDER balloon-borne telescope

We present the technology and control methods developed for the pointing system of the SPIDER experiment. SPIDER is a balloon-borne polarimeter designed to detect the imprint of primordial gravitational waves in the polarization of the Cosmic Microwave Background radiation. We describe the two main components of the telescope's azimuth drive: the reaction wheel and the motorized pivot. A 13 kHz PI control loop runs on a digital signal processor, with feedback from fibre optic rate gyroscopes. This system can control azimuthal speed with < 0.02 deg/s RMS error. To control elevation, SPIDER uses stepper-motor-driven linear actuators to rotate the cryostat, which houses the optical instruments, relative to the outer frame. With the velocity in each axis controlled in this way, higher-level control loops on the onboard flight computers can implement the pointing and scanning observation modes required for the experiment. We have accomplished the non-trivial task of scanning a 5000 lb payload sinusoidally in azimuth at a peak acceleration of 0.8 deg/s$^2$, and a peak speed of 6 deg/s. We can do so while reliably achieving sub-arcminute pointing control accuracy.Comment: 20 pages, 12 figures, Presented at SPIE Ground-based and Airborne Telescopes V, June 23, 2014. To be published in Proceedings of SPIE Volume 914