Development of the Next Generation of Meteoroid and Orbital Debris Shields

The novel structure of metallic foams is of interest in the design of next-generation debris shields as it introduces physical mechanisms that are advantageous to hypervelocity impact shielding (e.g. increased fragmentation/melt/vaporization, energy dissipation, etc.). Preliminary investigations have shown improved shielding capability over traditional spacecraft primary structures. In this paper, the results of a current hypervelocity impact test program on metallic open-cell foam core sandwich panels are reported. A preliminary ballistic limit equation has been derived from the experimental results, and is presented in a form suitable for implementation in risk assessment software codes

Piroplasms of New Zealand seabirds

Blood and ectoparasitic ticks were collected from migratory seabirds in New Zealand, including Australasian gannets (n=13) from two sites and red-billed gulls (n=9) and white-fronted terns (n=2) from a third location. Blood smears were screened for parasite presence by microscopy, while DNA from blood samples was subjected to PCR for the presence of tick-transmitted protozoan haemoparasites belonging to the order Piroplasmida. Parasites were identified by comparing small subunit ribosomal RNA (18S rDNA) gene sequences to related sequences on GenBank. Analyses indicated that nine birds were infected with unknown variants of a Babesia poelea-like parasite (recorded as genotypes I and II), while four harboured a piroplasm that was genetically similar to Babesia kiwiensis. There was no parasite stratification by bird species; both the gannets and gulls were positive for all three parasites, while the terns were positive for the B. kiwiensis-like and the B. poelea-like (genotype I) parasites. The B. kiwiensis-like parasite found in the birds was also found in two species of ticks: Carios capensis and Ixodes eudyptidis. This represents the first report of Babesia-positive ticks parasitising seabirds in New Zealand. The lack of host specificity and evidence of wide ranging distributions of the three piroplasm genotypes suggests there is a high degree of haemoparasite transmission occurring naturally between New Zealand seabird populations and species

Understanding plastic packaging: The co-evolution of materials and society

In recent years, the environmental problems associated with plastics have become a matter of global concern. Current responses seek to replace plastics with other materials, however it is not yet clear that these alternatives will deliver improved environmental outcomes. There remains an urgent need for more nuanced understandings of plastics, their role in society, and their environmental impacts. Drawing on social science perspectives that emphasise the co-evolution of materials and society, this paper outlines a socio-technical approach to plastics and social change. In this view, plastics are understood in terms of the networks and relations of which they are part – highlighting the limitations of both technological solutions and the blanket condemnation of particular materials. The analysis focuses specifically on plastic packaging, exploring the interplay of technological innovation and consumer practices to better account for processes of change. Our arguments are advanced through reference to three case studies: the launch of a ‘roast in the bag’ chicken by a food retailer, the switch to compostable packaging by a potato crisps (chips) brand, and the refilling of plastic bottles by a cosmetics company. Particular attention is paid to the relationships between commercial, environmental and regulatory concerns. To conclude, we consider implications of the approach presented here for transdisciplinary and policy debates about the problems associated with single-use plastics

What is the “right” number of hospital beds for palliative population health needs?

Healthcare services are one of the twelve determinants of population health. While all types of healthcare services are important, timely access to hospital-based care when needed is critical. For three decades, long waits and wait lists for hospital admission and inpatient care have been a concern in Canada. Undersupply of hospital beds to meet population needs may be the cause of this as hospitals were downsized due to government funding cutbacks and hospital expansion has not occurred since despite population growth and aging. The availability of hospital beds for palliative population health needs may therefore be an issue, particularly as longstanding concern exists about terminally-ill and dying people being frequently admitted to hospital and having long hospital stays. A decline in hospital deaths in many developed countries, including Canada, could indicate that palliative population needs for hospital-based care are not being met. This paper compares the number of hospitals and hospital beds that exist in 9 Canadian provinces and 15 developed countries in relation to population and spatial considerations in an attempt to determine an optimal number of hospital beds for the general public and thus also palliative population health needs. Methods: Document analysis. Publicly-available hospital, population, and geographic information was sought for 9 Canadian provinces and 15 developed countries and compared. Results: Major differences in citizen to hospital bed ratios and citizen to hospital ratios across provinces and countries were found. The availability of hospitals and hospital beds clearly varies. Conclusion: Some regions may have too few hospitals and hospital beds to meet the palliative and other care needs of their citizens. Sufficient beds should exist so necessary admissions to hospital can occur without harmful delay

Atypical Femur Fracture Risk versus Fragility Fracture Prevention with Bisphosphonates

BACKGROUND Bisphosphonates are effective in reducing hip and osteoporotic fractures. However, concerns about atypical femur fractures have contributed to substantially decreased bisphosphonate use, and the incidence of hip fractures may be increasing. Important uncertainties remain regarding the association between atypical femur fractures and bisphosphonates and other risk factors. METHODS We studied women 50 years of age or older who were receiving bisphosphonates and who were enrolled in the Kaiser Permanente Southern California health care system; women were followed from January 1, 2007, to November 30, 2017. The primary outcome was atypical femur fracture. Data on risk factors, including bisphosphonate use, were obtained from electronic health records. Fractures were radiographically adjudicated. Multivariable Cox models were used. The risk–benefit profile was modeled for 1 to 10 years of bisphosphonate use to compare associated atypical fractures with other fractures prevented. RESULTS Among 196,129 women, 277 atypical femur fractures occurred. After multivariable adjustment, the risk of atypical fracture increased with longer duration of bisphosphonate use: the hazard ratio as compared with less than 3 months increased from 8.86 (95% confidence interval [CI], 2.79 to 28.20) for 3 years to less than 5 years to 43.51 (95% CI, 13.70 to 138.15) for 8 years or more. Other risk factors included race (hazard ratio for Asians vs. Whites, 4.84; 95% CI, 3.57 to 6.56), height, weight, and glucocorticoid use. Bisphosphonate discontinuation was associated with a rapid decrease in the risk of atypical fracture. Decreases in the risk of osteoporotic and hip fractures during 1 to 10 years of bisphosphonate use far outweighed the increased risk of atypical fracture among Whites but less so among Asians. After 3 years, 149 hip fractures were prevented and 2 bisphosphonate-associated atypical fractures occurred in Whites, as compared with 91 and 8, respectively, in Asians. CONCLUSIONS The risk of atypical femur fracture increased with longer duration of bisphosphonate use and rapidly decreased after bisphosphonate discontinuation. Asians had a higher risk than Whites. The absolute risk of atypical femur fracture remained very low as compared with reductions in the risk of hip and other fractures with bisphosphonate treatment. (Funded by Kaiser Permanente and others.

Perceived and Actual Breast Cancer Risk

Perceived risk can influence health behaviors. Studies using various populations and breast cancer risk bias assessment methods have identified both risk over- and underestimation. Among 1803 women in primary care settings, 47 percent were at average epidemiologic risk (Gail-calculated relative risk ±50 percent of age-adjusted population average) and 55 percent perceived themselves to be at average risk (compared to same-age others) but there were mismatches or ‘biases’: 31 percent underestimated personal risk; 26 percent overestimated. Multiple logistic regression revealed that smokers were more likely to overestimate risk. Overestimation decreased with more education. Mammography use did not independently predict perception bias but, among never-screened women aged over 40 years, those contemplating mammograms were most likely to overestimate risk; precontemplators were most likely to underestimate. Implications for research and intervention are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66881/2/10.1177_135910539800300203.pd

Metal enrichment processes

There are many processes that can transport gas from the galaxies to their environment and enrich the environment in this way with metals. These metal enrichment processes have a large influence on the evolution of both the galaxies and their environment. Various processes can contribute to the gas transfer: ram-pressure stripping, galactic winds, AGN outflows, galaxy-galaxy interactions and others. We review their observational evidence, corresponding simulations, their efficiencies, and their time scales as far as they are known to date. It seems that all processes can contribute to the enrichment. There is not a single process that always dominates the enrichment, because the efficiencies of the processes vary strongly with galaxy and environmental properties.Comment: 18 pages, 8 figures, accepted for publication in Space Science Reviews, special issue "Clusters of galaxies: beyond the thermal view", Editor J.S. Kaastra, Chapter 17; work done by an international team at the International Space Science Institute (ISSI), Bern, organised by J.S. Kaastra, A.M. Bykov, S. Schindler & J.A.M. Bleeke

Exact Hypersurface-Homogeneous Solutions in Cosmology and Astrophysics

A framework is introduced which explains the existence and similarities of most exact solutions of the Einstein equations with a wide range of sources for the class of hypersurface-homogeneous spacetimes which admit a Hamiltonian formulation. This class includes the spatially homogeneous cosmological models and the astrophysically interesting static spherically symmetric models as well as the stationary cylindrically symmetric models. The framework involves methods for finding and exploiting hidden symmetries and invariant submanifolds of the Hamiltonian formulation of the field equations. It unifies, simplifies and extends most known work on hypersurface-homogeneous exact solutions. It is shown that the same framework is also relevant to gravitational theories with a similar structure, like Brans-Dicke or higher-dimensional theories.Comment: 41 pages, REVTEX/LaTeX 2.09 file (don't use LaTeX2e !!!) Accepted for publication in Phys. Rev.

Higher spin quaternion waves in the Klein-Gordon theory

Electromagnetic interactions are discussed in the context of the Klein-Gordon fermion equation. The Mott scattering amplitude is derived in leading order perturbation theory and the result of the Dirac theory is reproduced except for an overall factor of sixteen. The discrepancy is not resolved as the study points into another direction. The vertex structures involved in the scattering calculations indicate the relevance of a modified Klein-Gordon equation, which takes into account the number of polarization states of the considered quantum field. In this equation the d'Alembertian is acting on quaternion-like plane waves, which can be generalized to representations of arbitrary spin. The method provides the same relation between mass and spin that has been found previously by Majorana, Gelfand, and Yaglom in infinite spin theories