Why is there no cannery in ‘Cannery Row'? Exploring a behavioral simulation model of population extinction

Available ecological models of organizations do not provide satisfactory explanation for population extinction. In this article, we search for a minimal set of assumptions needed to expand the range of dynamic behaviors of the ecological model of density dependence to admit extinction while preserving its original insight. The revised version of the model builds on two core assumptions. The first is that organizational populations are linked to their environments through feedback processes of resource generation and consumption. As a consequence, the carrying capacity for an organizational population changes systematically with its density. The second assumption is that organizational vital rates respond with delay to changes in the level of available resources. As a consequence, organizational founding and mortality rates are affected by expectations that decision makers form about the future state of their environment. Using computer simulation, we test these assumptions and show that the relative speed at which processes of resource regeneration and consumption happen, and the speed at which expectations about future levels of resources are revised jointly determine a wide range of evolutionary trajectories that admit population extinction as one distinct possibility. The model is validated using multivariate sensitivity analysis techniques. We discuss the implications of our findings in the broader context of the current debate on the implications of selective sampling in the study of organizational population

Transitioning towards a 100% solar-hydro based generation: A system dynamic approach

Many countries have targeted a gradual transition towards 100% green generation; however, there is uncertainty concerning the economic and social consequences of such a transition. The main technologies that have been implemented are hydro, wind and solar. The latter two could cause an increase in electricity prices due to a mismatch between demand and supply. This paper uses a system dynamics approach to analyze the transition process of Switzerland, which is gradually moving from nuclear towards solar and hydro base generation. We consider hydro-pumped storage to address the timing problem between supply and demand. We developed different scenarios to test the viability of such a system. Our findings indicate that leaving the system to a free market will entail shortages during the transition, as well as a doubling of the electricity price. To mitigate this effect, we propose a capacity auction mechanism to smooth the transition process. We find that subsidizing PV indirectly encourages storage, thereby eliminating shortages, and mitigating the increase in the electricity price during the transition

Quality of life in female myocardial infarction survivors: a comparative study with a randomly selected general female population cohort

Background: A substantial burden associated with MI has been reported. Thus, how survivors experience their quality of life (QOL) is now being given increasing attention. However, few studies have involved women and a comparison with the general population. The aims of this study were to determine the QOL of female MI survivors, to investigate whether their QOL differed from that of the general population, and to evaluate the clinical significance of the findings. Methods: Two cross-sectional surveys were performed; on female MI survivors and the general Norwegian population. The MI survey included women aged 62–80 years, three months to five years after their MI. One hundred and forty-five women responded, yielding a response rate of 60%. A subset of women in the same age range (n = 156) was drawn from a study of 1893 randomly selected Norwegian citizens. QOL was measured in both groups with the World Health Organization Quality of Life Instrument Abbreviated (WHOQOL-BREF). Results: The majority (54%) of the female MI survivors presented with ST-elevation in their ECG, 31% received thrombolysis, and 38% had reduced left ventricular ejection fraction. Female MI survivors reported significantly lower satisfaction with general health (p = 0.020) and overall QOL (p = 0.017) than women from the general population. This was also the case for the physical and environmental QOL domains (p < 0.001), but not for the psychological and social relationship domains. Estimated effect sizes between the two groups of participants ranged from 0.1 to -0.6. Conclusion: The burden of MI significantly affects the physical health of elderly women. Still, female MI survivors fare as well as the general female population on psychosocial QOL domains. Action should be taken not only to support women's physical needs but also to reinforce their strengths in order to maintain optimal QOL

Long-term, treatment-free survival in select patients with distant metastatic papillary thyroid cancer

Well-differentiated thyroid carcinoma (WDTC) generally has a favorable prognosis. However, patients with distant metastatic disease experience progression of disease with a higher mortality. A subset of patients not previously described may challenge the conventional dogma regarding the progressive nature of all metastatic WDTC. Through analysis of our database, we identified patients with distant metastatic WDTC and persistent, minimally progressive disease. In all patients, persistent metastatic disease was confirmed via tissue biopsy, abnormal PET scan, and/or biochemical elevations in thyroglobulin or antibody levels. Progression of disease was monitored clinically and with repeat imaging. We describe five patients with WDTC and pulmonary metastases, aged 8–43 years at diagnosis. All patients underwent initial surgery and radioactive iodine (RAI) ablation, with some receiving multiple treatments. Persistent pulmonary metastatic disease was confirmed over decades (mean 22 years, range 8–42 years) with minimal progression despite no further treatment beyond thyroid hormone suppression. Persistent disease was biopsy-proven in all patients at a mean of 9.6 years from last RAI treatment. All patients had elevated thyroglobulin or anti-thyroglobulin antibody levels, while three demonstrated metabolically active disease with positive FDG uptake on PET scan, and one patient with persistent radioactive iodine avid pulmonary metastasis 36 years after her last RAI treatment. This case series demonstrates that some patients with distant metastases, even if metabolically active and radioactive iodine resistant, remain stable for decades without further treatment. Clinical awareness of such patients and continual reassessment of disease risk following initial therapy are crucial as aggressive treatment may not be necessary