Genetic Variability of US and Czech Phalaris Arundinacea L. Wild and Cultivated Populations

The spread of invasive plant species in natural habitats has become a worldwide problem with negative impacts. Phalaris arundinacea, an important forage and ornamental crop, is widespread worldwide. In recent years there has been a massive spread of P. arundinacea across North America and Canada. Production of Phalaris seed as a forage crop occurs in northern Minnesota; seeds are sold throughout the world, particularly in central Europe. We tested genetic similarities and differences between populations in the US (Minnesota) and the Czech Republic using ISSRs to determine potential gene flow for this forage crop. The cultivated forage and wild genotypes were dispersed into two groups that overlapped. At least four sets of wild US genotypes are dissimilar to European counterparts and potentially native to N. America. Future work to prove the ancestry of each accession will be necessary. Nonetheless, the sale of forage cultivars related to or derived from European types causes genetic mixing with N. American types. Part of this intercontinental gene flow is exacerbated by the production of Phalaris forage seed in Minnesota. The implications of these findings for management of invasive crops native to both continents are significant for forage producers, managers, and breeders

Population genetic structure of N. American and European \u3ci\u3ePhalaris arundinacea\u3c/i\u3e L. as inferred from inter-simple sequence repeat markers

Phalaris arundinacea L. (reed canarygrass) has become one of the most aggressive invaders of North American wetlands. P. arundinacea is native to temperate N. America, Europe, and Asia, but repeated introductions of European genotypes to N. America, recent range expansions, and the planting of forage and ornamental cultivars complicate the resolution of its demographic history. Molecular tools can help to unravel the demographic and invasion history of populations of invasive species. In this study, inter-simple sequence repeat markers were used to analyze the population genetic structure of European and N. American populations of reed canary grass as well as forage and ornamental cultivars. We found that P. arundinacea harbors a high amount of genetic diversity with most of the diversity located within, as opposed to among, populations. Cluster analyses suggested that current populations are admixtures of two formerly distinct genetic groups

Space-based research in fundamental physics and quantum technologies

Space-based experiments today can uniquely address important questions related to the fundamental laws of Nature. In particular, high-accuracy physics experiments in space can test relativistic gravity and probe the physics beyond the Standard Model; they can perform direct detection of gravitational waves and are naturally suited for precision investigations in cosmology and astroparticle physics. In addition, atomic physics has recently shown substantial progress in the development of optical clocks and atom interferometers. If placed in space, these instruments could turn into powerful high-resolution quantum sensors greatly benefiting fundamental physics. We discuss the current status of space-based research in fundamental physics, its discovery potential, and its importance for modern science. We offer a set of recommendations to be considered by the upcoming National Academy of Sciences' Decadal Survey in Astronomy and Astrophysics. In our opinion, the Decadal Survey should include space-based research in fundamental physics as one of its focus areas. We recommend establishing an Astronomy and Astrophysics Advisory Committee's interagency ``Fundamental Physics Task Force'' to assess the status of both ground- and space-based efforts in the field, to identify the most important objectives, and to suggest the best ways to organize the work of several federal agencies involved. We also recommend establishing a new NASA-led interagency program in fundamental physics that will consolidate new technologies, prepare key instruments for future space missions, and build a strong scientific and engineering community. Our goal is to expand NASA's science objectives in space by including ``laboratory research in fundamental physics'' as an element in agency's ongoing space research efforts.Comment: a white paper, revtex, 27 pages, updated bibliograph

Towards resolution of the Fermi surface in underdoped high-Tc superconductors

We survey recent experimental results including quantum oscillations and complementary measurements probing the electronic structure of underdoped cuprates, and theoretical proposals to explain them. We discuss quantum oscillations measured at high magnetic fields in the underdoped cuprates that reveal a small Fermi surface section comprising quasiparticles that obey Fermi-Dirac statistics, unaccompanied by other states of comparable thermodynamic mass at the Fermi level. The location of the observed Fermi surface section at the nodes is indicated by a body of evidence including the collapse in Fermi velocity measured by quantum oscillations, which is found to be associated with the nodal density of states observed in angular resolved photoemission, the persistence of quantum oscillations down to low fields in the vortex state, the small value of density of states from heat capacity and the multiple frequency quantum oscillation pattern consistent with nodal magnetic breakdown of bilayer-split pockets. A nodal Fermi surface pocket is further consistent with the observation of a density of states at the Fermi level concentrated at the nodes in photoemission experiments, and the antinodal pseudogap observed by photoemission, optical conductivity, nuclear magnetic resonance Knight shift, as well as other complementary diffraction, transport and thermodynamic measurements. One of the possibilities considered is that the small Fermi surface pockets observed at high magnetic fields can be understood in terms of Fermi surface reconstruction by a form of small wavevector charge order, observed over long lengthscales in experiments such as nuclear magnetic resonance and x-ray scattering, potentially accompanied by an additional mechanism to gap the antinodal density of states.Comment: 33 pages, 15 figures (this version updated with new figures and additional text, as published

Tests of Lorentz symmetry using antihydrogen

Signals of CPT and Lorentz violation are possible in the context of spectroscopy using hydrogen and antihydrogen. We apply the Standard-Model Extension, a broad framework for Lorentz breaking in physics, to various transitions in the hydrogen and antihydrogen spectra. The results show an unsuppressed effect in the transition between the upper two hyperfine sublevels of the ground state of these systems. We also discuss related tests in Penning traps, and recent work on Lorentz violation in curved spacetime.Comment: 11pp, invited talk at PQE 37 Conference, Snowbird, Utah, USA, 2-6 Jan 200

A Computational Method Based on the Integration of Heterogeneous Networks for Predicting Disease-Gene Associations

The identification of disease-causing genes is a fundamental challenge in human health and of great importance in improving medical care, and provides a better understanding of gene functions. Recent computational approaches based on the interactions among human proteins and disease similarities have shown their power in tackling the issue. In this paper, a novel systematic and global method that integrates two heterogeneous networks for prioritizing candidate disease-causing genes is provided, based on the observation that genes causing the same or similar diseases tend to lie close to one another in a network of protein-protein interactions. In this method, the association score function between a query disease and a candidate gene is defined as the weighted sum of all the association scores between similar diseases and neighbouring genes. Moreover, the topological correlation of these two heterogeneous networks can be incorporated into the definition of the score function, and finally an iterative algorithm is designed for this issue. This method was tested with 10-fold cross-validation on all 1,126 diseases that have at least a known causal gene, and it ranked the correct gene as one of the top ten in 622 of all the 1,428 cases, significantly outperforming a state-of-the-art method called PRINCE. The results brought about by this method were applied to study three multi-factorial disorders: breast cancer, Alzheimer disease and diabetes mellitus type 2, and some suggestions of novel causal genes and candidate disease-causing subnetworks were provided for further investigation