Flapping dynamics of an inverted flag behind a cylinder.

The inverted flag configuration is inspired by biological structures (e.g. leaves on a tree branch), showing rich dynamics associated with instabilities at lower flow speeds than the regular flag configuration. In the biological counterpart, the arrangement of leaves and twigs on foliage creates a complex interacting environment that promotes certain dynamic fluttering modes. While enabling a large amplitude response for reduced flow speeds is advantageous in emerging fields such as energy harvesting, still, little is known about the consequence of such interactions. In this work, we numerically study the canonical bio-inspired problem of the flow-structural interaction of a 2D inverted flag behind a cylindrical bluff body, mimicking a leaf behind a tree branch, to investigate its distinct fluttering regimes. The separation distance between the cylinder and flag is gradually modified to determine the effective distance beyond which small-amplitude or large-amplitude flapping occurs for different flow velocities. It is shown that the flag exhibits a periodic large amplitude-low frequency response mode when the cylinder is placed at a sufficiently large distance in front of the flag. At smaller distances, when the flag is within the immediate wake of the cylinder, the flag undergoes a high frequency-small amplitude response. Finally, the flag's piezoelectric power harvesting capability is investigated numerically and experimentally for varying geometrical and electrical parameters associated with these two conditions. Two separate optimal response modes with the highest energy output have also been identified.

A potential decline in life expectancy in the United States in the 21st century.

Forecasts of life expectancy are an important component of public policy that influence age-based entitlement programs such as Social Security and Medicare. Although the Social Security Administration recently raised its estimates of how long Americans are going to live in the 21st century, current trends in obesity in the United States suggest that these estimates may not be accurate. From our analysis of the effect of obesity on longevity, we conclude that the steady rise in life expectancy during the past two centuries may soon come to an end.

Biodemographic perspectives for epidemiologists.

A new scientific discipline arose in the late 20th century known as biodemography. When applied to aging, biodemography is the scientific study of common age patterns and causes of death observed among humans and other sexually reproducing species and the biological forces that contribute to them. Biodemography is interdisciplinary, involving a combination of the population sciences and such fields as molecular and evolutionary biology. Researchers in this emerging field have discovered attributes of aging and death in humans that may very well change the way epidemiologists view and study the causes and expression of disease. In this paper, the biodemography of aging is introduced in light of traditional epidemiologic models of disease causation and death.

Effect of population aging on proportionate mortality from heart disease and cancer, U.S. 2000-2050.

OBJECTIVE: One-fourth of all deaths in the United States occur after age 85 (646,900 of 2,392,619 total deaths in 1999). By 2050 (assuming 1999 age-specific death rates), 47.4% of all deaths will occur after age 85 (2,994,935 of 6,314,725 total deaths). As we age, heart disease becomes increasingly important relative to cancer as a cause of death. Thus, as age at death is postponed, future populations will be dying of different age-specific causes. The study objective was to project the effect of population aging on future proportionate mortality rates for heart disease and cancer. METHODS: Using Census Bureau population projections and assuming 1999 age-specific death rates, the authors calculated the number of deaths from heart disease, cancer, and all causes in 10-year intervals from 2000 to 2050. RESULT: During this period, the total number of deaths for heart disease and cancer will increase 2.8-fold and 2.3-fold, respectively. The proportionate mortality rate for heart disease will increase from 30% to 33%, and the rate for cancer will drop from 23% to 20%. DISCUSSION: Changes in age distribution between now and 2050 will cause heart disease to increase its dominance over all other causes of death, and proportionate mortality for cancer will decline.

Misdirection on the road to Shangri-La.

Will life expectancy in the United States rise or fall in this century? The implications of either scenario are far reaching. We contend that the rise of childhood obesity in the United States in the past three decades has been so dramatic that it will soon lead to higher than expected death rates at middle ages and a possible decline in life expectancy by midcentury. The most detrimental health and longevity effects will not be seen for decades--a phenomenon that cannot be detected by current methods used to forecast life expectancy or estimate the number of deaths currently attributable to obesity. This scenario contrasts sharply with the views of mathematical demographers who generate forecasts by relying on the assumption that the U.S. pattern of longevity will follow that of other longer lived nations and on the extrapolation of historical trends in life expectancy into the future.

Misdirection on the road to Shangri-La.

Will life expectancy in the United States rise or fall in this century? The implications of either scenario are far reaching. We contend that the rise of childhood obesity in the United States in the past three decades has been so dramatic that it will soon lead to higher than expected death rates at middle ages and a possible decline in life expectancy by midcentury. The most detrimental health and longevity effects will not be seen for decades--a phenomenon that cannot be detected by current methods used to forecast life expectancy or estimate the number of deaths currently attributable to obesity. This scenario contrasts sharply with the views of mathematical demographers who generate forecasts by relying on the assumption that the U.S. pattern of longevity will follow that of other longer lived nations and on the extrapolation of historical trends in life expectancy into the future.

Peering into the future of American longevity.

Extract: The trend in the life expectancy of humans during the past thousand years has been generally characterized by a slow, steady increase -- though this pattern is frequently punctuated by volatility in death rates caused by epidemic and pandemic infectious diseases, famines, and war. This volatility was dramatically curtailed in the mid-19th century as infectious agents swiftly succumbed to improved living conditions, advances in public health, and medical interventions. During the past 30 years in the United States, the rise in life expectancy at birth has decelerated relative to this historic pattern, and gains in life expectancy at older ages are now much smaller than they were in previous decades. How much higher can life expectancy rise? This is not just an academic question. The answer formulated today will have substantial influence on the rate at which taxes are levied and the potential solvency of age-entitlement programs. Some researchers predict that life expectancy will rise dramatically in this century, leading public policy makers to raise their estimates of how long Americans will live. It is predicted that historical trends in rising life expectancy will continue throughout this century, fueled primarily by anticipated but yet-to-exist advances in biomedical technology. Some have even predicted that aging itself will soon be mastered by science, enabling people to live well beyond 100 years.

Musical experience and dementia. Hypothesis.

BACKGROUND AND AIMS: Cognitively stimulating activities appear to protect against the development of dementing illness--playing a musical instrument may be one of these activities. Consistent with this notion, the aim of this study was to explore the hypothesis that dementia might be less common among orchestral musicians. METHODS: A cross-sectional survey of 23 older orchestral musicians who were former members of a single orchestra was carried out. Prior musical background, family history, and health history were obtained. A cognitive screen was administered in person or by telephone. Musicians were also queried regarding their awareness of living former orchestral colleagues with dementia. RESULTS: The mean age of participants was 76.9 +/- 6.8 (SD). No participant was aware of a living former or current orchestral member with either reported or suspected dementia. CONCLUSIONS: The results are consistent with the hypothesis that dementing illness may be less among orchestral musicians--possibly from a lifetime engaged in a cognitively stimulating endeavor.