Multiple queens means fewer mates

SummaryObligate multiple mating by social insect queens has evolved in some derived clades where higher genetic diversity is likely to enhance colony fitness [1–3]. The rare and derived nature of this behaviour is probably related to copulations being costly for queens, but fitness trade-offs between immediate survival and future reproductive success are difficult to measure and not well understood [1]. A corollary of this logic, that multiple mating should be less common or lost when genetic diversity among workers is achieved through multiple queens per colony, was suggested more than ten years ago [4]. However, large scale comparative analyses did not support this prediction, quite possibly because they did not contain any informative contrasts [1,2]. Only comparisons between closely related species with similar ecology and high queen-mating frequencies as ancestral state would provide decisive information, but such species pairs are exceedingly rare so that no case studies have been conducted and a comparative statistical approach [5] is impossible. Here we document for the first time that there is a clear link between the number of queens and the average number of matings of these queens, using the army ant Neivamyrmex carolinensis as a model system

Addendum to “Bending the Medicare Cost Curve in 12 Months or Less”: AHS Analysis for Sample of Pure North Seniors (55-plus)

As part of our analysis in the paper published in January 2015, “Bending the Medicare Cost Curve in 12 Months or Less: How Preventative Health Care Can Yield Significant Near-Term Savings for Acute Care in Alberta,”1 we had carried out analyses of sub-groups of interest, such as workers at Canadian Natural Resources Ltd. (CNRL) and seniors (participants aged 55-plus) that, for reasons of length, we did not include in the published paper. The details for the data, the models estimated, the statistics calculated and the sample inclusion and exclusion restrictions are described in the full paper that was peer reviewed. This addendum discusses the results of the analysis of the sample of seniors (participants aged 55 and up at the time of joining Pure North, n=5,516, made up of 2,758 Pure North participants and 2,758 age- and sex-matched controls). The models estimated are described on pages 9 and 10 of the published paper. Persisting participants are Pure North joiners who have a 25OHD (vitamin D blood serum) measure at the time of joining and one year later. We interpret participants with two 25OHD one year apart as persisting in the Pure North program but we do not infer the degree of adherence to the program. The In-Clinic Seniors Program (ICP) sub-sample of Pure North senior participants had over 90 per cent persistence in the program for at least one year. For this sub-sample, relative to the frequency of hospital and emergency department visits of the ICP seniors program participants and matched controls in the year prior to joining the program, the program reduces hospital visits for seniors in the program by 22 per cent, emergency department visits by 34 per cent and avoids 22 per cent of annual health-care costs. For the 68 per cent of the full sample of Pure North participants aged 55 and over who we can confirm persisted in the program for at least one year, relative to the frequency of hospital and emergency department visits of the program participants and matched controls in the year prior to joining the program, the program reduces hospital visits for seniors persisting in the program by 39 per cent and emergency department visits by 24 per cent. These reductions in health care system contacts result in public health-care expenditures avoided of 35 per cent per year. These magnitudes are comparable to what we calculated for the overall and Vital 2.2 samples in the full 2015 report.Not accounted for in those direct health-care costs avoided is the relief that preventative care can provide to the medical treatment system. Scaled to the population level, the reductions observed in the Pure North seniors sample would represent at least six per cent fewer visits to Alberta emergency departments per year and reduce the need for hospital beds by at least six per cent in the Alberta hospital system. In terms of freed-up hospital beds, this is equivalent to adding another Foothills Medical Centre to the Alberta health-care system

The Private Insurance Debate In Canadian Health Policy: Making the Values Explicit

Should Canadian governments prohibit private insurance for services parallel to those provided in the publicly insured health care system? We believe that the values engaged by this issue have not been made clear and explicit in health policy discussion and debate. With reference to the recent Chaoulli case at the Supreme Court of Canada, we articulate what we take to be the main values in tension and conflict, and distinguish three main value-based positions on the policy issue. By doing so we hope to contribute to a more informed, explicit and open public policy discussion

Hole Pockets in the Doped 2D Hubbard Model

The electronic momentum distribution ${\rm n({\bf k})}$ of the two dimensional Hubbard model is studied for different values of the coupling ${\rm U/t}$, electronic density ${\rm \langle n \rangle}$, and temperature, using quantum Monte Carlo techniques. A detailed analysis of the data on $8\times 8$ clusters shows that features consistent with hole pockets at momenta ${\rm {\bf k}=(\pm {\pi\over{2}},\pm {\pi\over{2}})}$ appear as the system is doped away from half-filling. Our results are consistent with recent experimental data for the cuprates discussed by Aebi et al. (Phys. Rev. Lett. {\bf 72}, 2757 (1994)). In the range of couplings studied, the depth of the pockets is maximum at ${\rm \langle n \rangle \approx 0.9}$, and it increases with decreasing temperature. The apparent absence of hole pockets in previous numerical studies of this model is explained.Comment: 11 pages, 4 postscript figures appended, RevTeX (version 3.0

Amphibia: Anura: Hylidae Scarthyla vigilans (Solano 1971): Range Extension and New Country Record for Trinidad, W.I. With Notes on Tadpoles, Habitat, Behaviour and Biogeographical Significance.

We report a range extension and new country record for Scarthyla vigilans in Trinidad, West Indies. The species was previously known only from populations on mainland South America. We include notes on behavior, habitat and tadpole development, and discuss the biogeographical significance of the species’ presence in Trinidad, particularly with respect to consequences for understanding colonization events on this Caribbean island

Non-nest mate discrimination and clonal colony structure in the parthenogenetic ant Cerapachys biroi

Understanding the interplay between cooperation and conflict in social groups is a major goal of biology. One important factor is genetic relatedness, and animal societies are usually composed of related but genetically different individuals, setting the stage for conflicts over reproductive allocation. Recently, however, it has been found that several ant species reproduce predominantly asexually. Although this can potentially give rise to clonal societies, in the few well-studied cases, colonies are often chimeric assemblies of different genotypes, due to worker drifting or colony fusion. In the ant Cerapachys biroi, queens are absent and all individuals reproduce via thelytokous parthenogenesis, making this species an ideal study system of asexual reproduction and its consequences for social dynamics. Here, we show that colonies in our study population on Okinawa, Japan, recognize and effectively discriminate against foreign workers, especially those from unrelated asexual lineages. In accord with this finding, colonies never contained more than a single asexual lineage and average pairwise genetic relatedness within colonies was extremely high (r = 0.99). This implies that the scope for social conflict in C. biroi is limited, with unusually high potential for cooperation and altruis

The Fiscal, Social and Economic Dividends of Feeling Better and Living Longer

While Canada has socialized most of the costs of treating illness, Canada has maintained a reliance on individuals interacting through private markets to invest in upstream health promotion and disease prevention. The failure of the market to provide the efficient level of upstream investment in health is leading to large and avoidable increases in the need for downstream medical treatment. The way to reduce the future deadweight loss of illness and disease is for provincial governments to address the upstream market failures through an expansion of the scope of public payment for health care to include upstream services for health promotion and disease prevention. Perhaps somewhat counterintuitively, spending public health-care dollars across a broader range of health and wellness services can result in spending less in total, because of the efficiency gains that will come from better health in the population. That is certainly what the evidence from a unique Albertan pilot project leads us to conclude. The Pure North S’Energy Foundation is a philanthropic initiative that pays for and provides preventative health-care services for Albertans drawn from groups that are vulnerable to poor health. This includes homeless people, people suffering from addiction, people with low incomes, people in isolated areas and susceptible seniors. The health improvements observed in those participating in the Pure North program have been significant. Effective health-promotion and disease-prevention services obviously benefit patients. But there are also substantial benefits to society as well. The annual health-care bill for a Canadian in poor health is estimated to be more than $10,000 higher than for someone in good health, meaning that keeping people in good health can be an important means for controlling public health-care budgets, and can free up scarce acutecare hospital resources. If the Pure North program were scaled-up province-wide to cover the nearly quartermillion Albertans in poor health, the resulting health improvement seen in Pure North participants could translate into a nearly 25-per-cent reduction in hospital days used by Alberta patients every year and a net savings of$500 million on hospital and physician costs. That does not even include the economic benefits of keeping workers in better health and productive, while spending fewer days ill or hospitalized. To date, Canada’s approach to health care has largely left it to patients to choose whether to seek healthpromotion and disease-prevention services on their own, suggesting an implicit deference to an individual’s rights and responsibilities. But for many low-income, isolated, addicted or aboriginal Canadians, there often is no choice: These services, when delivered privately, are often too expensive or may be otherwise inaccessible. The initial spirit behind Canadian medicare was to correct a health-market failure, so that no patient would face barriers to accessing necessary treatments. That same philosophy also recommends extending universal coverage for health-promotion and disease-prevention to vulnerable Canadians who today face similar barriers to access. If the Alberta government wants to show both foresight and fairness, the benefits from this kind of program, economically and societally, are simply too attractive to disregard

Combined shear/compression structural testing of asymmetric sandwich structures

Asymmetric sandwich technology can be applied in the design of lightweight, non-pressurized aeronautical structures such as those of helicopters. A test rig of asymmetric sandwich structures subjected to compression/shear loads was designed, validated, and set up. It conforms to the standard certification procedure for composite aeronautical structures set out in the “test pyramid”, a multiscale approach. The static tests until failure showed asymmetric sandwich structures to be extremely resistant, which, in the case of the tested specimen shape, were characterized by the absence of buckling and failure compressive strains up to 10,000 μ strains. Specimens impacted with perforation damage were also tested, enabling the original phenomenon of crack propagation to be observed step-by-step. The results of the completed tests thus enable the concept to be validated, and justify the possibility of creating a much larger machine to overcome the drawbacks linked to the use of small specimens