Low-Energy Shape Resonances of a Nucleobase in Water

When high-energy radiation passes through aqueous material, low-energy electrons are produced which cause DNA damage. Electronic states of anionic nucleobases have been suggested as an entrance channel to capture the electron. However, identifying these electronic resonances have been restricted to gas-phase electron-nucleobase studies and offer limited insight into the resonances available within the aqueous environment of DNA. Here, resonance and detachment energies of the micro-hydrated uracil pyrimidine nucleobase anion are determined by two-dimensional photoelectron spectroscopy and are shown to extrapolate linearly with cluster size. This extrapolation allows the corresponding resonance and detachment energies to be determined for uracil in aqueous solution as well as the reorganization energy associated with electron capture. Two shape resonances are clearly identified that can capture low-energy electrons and subsequently form the radical anion by solvent stabilization and internal conversion to the ground electronic state. The resonances and their dynamics probed here are the nucleobase-centered doorway states for low-energy electron capture and damage in DNA

Host genetics of response to porcine reproductive and respiratory syndrome in nursery pigs

PRRS is the most costly disease in the US pig industry. While vaccination, biosecurity and eradication effort have had some success, the variability and infectiousness of PRRS virus strains have hampered the effectiveness of these measures. We propose the use of genetic selection of pigs as an additional and complementary effort. Several studies have shown that host response to PRRS infection has a sizeable genetic component and recent advances in genomics provide opportunities to capitalize on these genetic differences and improve our understanding of host response to PRRS. While work is also ongoing to understand the genetic basis of host response to reproductive PRRS, the focus of this review is on research conducted on host response to PRRS in the nursery and grow-finish phase as part of the PRRS Host Genetics Consortium. Using experimental infection of large numbers of commercial nursery pigs, combined with deep phenotyping and genomics, this research has identified a major gene that is associated with host response to PRRS. Further functional genomics work identified the GBP5 gene as harboring the putative causative mutation. GBP5 is associated with innate immune response. Subsequent work has validated the effect of this genomic region on host response to a second PRRSV strain and to PRRS vaccination and co-infection of nursery pigs with PRRSV and PCV2b. A genetic marker near GBP5 is available to the industry for use in selection. Genetic differences in host response beyond GBP5 appear to be highly polygenic, i.e. controlled by many genes across the genome, each with a small effect. Such effects can by capitalized on in a selection program using genomic prediction on large numbers of genetic markers across the genome. Additional work has also identified the genetic basis of antibody response to PRRS, which could lead to the use of vaccine response as an indicator trait to select for host response to PRRS. Other genomic analyses, including gene expression analyses, have identified genes and modules of genes that are associated with differences in host response to PRRS and can be used to further understand and utilize differences in host response. Together, these results demonstrate that genetic selection can be an additional and complementary tool to combat PRRS in the swine industry

Dielectronic Recombination in Li+ Ions

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Dielectronic Recombination in Li+ Ions

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Distribution modelling and statistical phylogeography: an integrative framework for generating and testing alternative biogeographical hypotheses

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73644/1/j.1365-2699.2007.01814.x.pd

Measurements of Dielectronic Recombination in He+ Ions

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Dielectronic Recombination in He+ Ions

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

A novel determination of the local dark matter density

We present a novel study on the problem of constructing mass models for the Milky Way, concentrating on features regarding the dark matter halo component. We have considered a variegated sample of dynamical observables for the Galaxy, including several results which have appeared recently, and studied a 7- or 8-dimensional parameter space - defining the Galaxy model - by implementing a Bayesian approach to the parameter estimation based on a Markov Chain Monte Carlo method. The main result of this analysis is a novel determination of the local dark matter halo density which, assuming spherical symmetry and either an Einasto or an NFW density profile is found to be around 0.39 GeV cm$^{-3}$ with a 1-$\sigma$ error bar of about 7%; more precisely we find a $\rho_{DM}(R_0) = 0.385 \pm 0.027 \rm GeV cm^{-3}$ for the Einasto profile and $\rho_{DM}(R_0) = 0.389 \pm 0.025 \rm GeV cm^{-3}$ for the NFW. This is in contrast to the standard assumption that $\rho_{DM}(R_0)$ is about 0.3 GeV cm$^{-3}$ with an uncertainty of a factor of 2 to 3. A very precise determination of the local halo density is very important for interpreting direct dark matter detection experiments. Indeed the results we produced, together with the recent accurate determination of the local circular velocity, should be very useful to considerably narrow astrophysical uncertainties on direct dark matter detection.Comment: 31 pages,11 figures; minor changes in the text; two figures adde

A Bayesian view of the current status of dark matter direct searches

Bayesian statistical methods offer a simple and consistent framework for incorporating uncertainties into a multi-parameter inference problem. In this work we apply these methods to a selection of current direct dark matter searches. We consider the simplest scenario of spin-independent elastic WIMP scattering, and infer the WIMP mass and cross-section from the experimental data with the essential systematic uncertainties folded into the analysis. We find that when uncertainties in the scintillation efficiency of Xenon100 have been accounted for, the resulting exclusion limit is not sufficiently constraining to rule out the CoGeNT preferred parameter region, contrary to previous claims. In the same vein, we also investigate the impact of astrophysical uncertainties on the preferred WIMP parameters. We find that within the class of smooth and isotropic WIMP velocity distributions, it is difficult to reconcile the DAMA and the CoGeNT preferred regions by tweaking the astrophysics parameters alone. If we demand compatibility between these experiments, then the inference process naturally concludes that a high value for the sodium quenching factor for DAMA is preferred.Comment: 37 pages, 14 figures and 7 tables. Replacement for matching the version accepted for publicatio