25 research outputs found
Detecting bubbles in exotic nuclei
The occurrence of a bubble, due to an inversion of s state with the
state usually located above, is investigated. Proton bubbles in neutron-rich
Argon isotopes are optimal candidates. Pairing effects which can play against
the bubble formation are evaluated. They cannot prevent bubble formation in
very neutron-rich argon isotopes such as Ar. This pleads for a
measurement of the charge density of neutron-rich argon isotopes in the
forthcoming years, with the advent of electron scattering experiments in next
generation exotic beam facilities such as FAIR or RIBF.Comment: 6 pages, 5 figures, to be published in Nucl. Phys.
Structural alterations in a type IV pilus subunit protein result in concurrent defects in multicellular behaviour and adherence to host tissue
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72384/1/j.1365-2958.2001.02629.x.pd
Carpet-dust chemicals as measures of exposure: Implications of variability
<p>Abstract</p> <p>Background</p> <p>There is increasing interest in using chemicals measured in carpet dust as indicators of chemical exposures. However, investigators have rarely sampled dust repeatedly from the same households and therefore little is known about the variability of chemical levels that exist within and between households in dust samples.</p> <p>Results</p> <p>We analyzed 9 polycyclic aromatic hydrocarbons, 6 polychlorinated biphenyls, and nicotine in 68 carpet-dust samples from 21 households in agricultural communities of Fresno County, California collected from 2003-2005. Chemical concentrations (ng per g dust) ranged from < 2-3,609 for 9 polycyclic aromatic hydrocarbons, from < 1-150 for 6 polychlorinated biphenyls, and from < 20-7,776 for nicotine. We used random-effects models to estimate variance components for concentrations of each of these carpet-dust chemicals and calculated the variance ratio, λ, defined as the ratio of the within-household variance component to the between-household variance component. Subsequently, we used the variance ratios calculated from our data, to illustrate the potential effect of measurement error on the attenuation of odds ratios in hypothetical case-control studies. We found that the median value of the estimated variance ratios was 0.33 (range: 0.13-0.72). Correspondingly, in case-control studies of associations between these carpet-dust chemicals and disease, given the collection of only one measurement per household and a hypothetical odds ratio of 1.5, we expect that the observed odds ratios would range from 1.27 to 1.43. Moreover, for each of the chemicals analyzed, the collection of three repeated dust samples would limit the expected magnitude of odds ratio attenuation to less than 20%.</p> <p>Conclusions</p> <p>Our findings suggest that attenuation bias should be relatively modest when using these semi-volatile carpet-dust chemicals as exposure surrogates in epidemiologic studies.</p
LivestockPlus: The sustainable intensification of forage-based agricultural systems to improve livelihoods and ecosystem services in the tropics
As global demand for livestock products (such as meat, milk, and eggs) is expected to double by 2050, necessary
increases to future production must be reconciled with negative environmental impacts that livestock cause. This
paper describes the LivestockPlus concept and demonstrates how the sowing of improved forages can lead to the
sustainable intensification of mixed cropâforageâlivestockâtree systems in the tropics by producing multiple social,
economic, and environmental benefits. Sustainable intensification not only improves the productivity of tropical
forage-based systems but also reduces the ecological footprint of livestock production and generates a diversity of
ecosystem services (ES), such as improved soil quality and reduced erosion, sedimentation, and greenhouse gas
(GHG) emissions. Integrating improved grass and legume forages into mixed production systems (cropâlivestock,
treeâlivestock, cropâtreeâlivestock) can restore degraded lands and enhance system resilience to drought and
waterlogging associated with climate change. When properly managed tropical forages accumulate large amounts
of carbon in soil, fix atmospheric nitrogen (legumes), inhibit nitrification in soil and reduce nitrous oxide emissions
(grasses), and reduce GHG emissions per unit livestock product.
The LivestockPlus concept is defined as the sustainable intensification of forage-based systems, which is based
on three interrelated intensification processes: genetic intensification â the development and use of superior
grass and legume cultivars for increased livestock productivity; ecological intensification â the development and
application of improved farm and natural resource management practices; and socio-economic intensification
â the improvement of local and national institutions and policies, which enable refinements of technologies
and support their enduring use. Increases in livestock productivity will require coordinated efforts to develop
supportive government, non-government organization, and private sector policies that foster investments and
fair market compensation for both the products and ES provided. Effective research-for-development efforts that
promote agricultural and environmental benefits of forage-based systems can contribute towards implemention of
LivestockPlus across a variety of geographic, political, and socio-economic contexts