Evolution of genetic potential.

Organisms employ a multitude of strategies to cope with the dynamical environments in which they live. Homeostasis and physiological plasticity buffer changes within the lifetime of an organism, while stochastic developmental programs and hypermutability track changes on longer time-scales. An alternative long-term mechanism is "genetic potential"--a heightened sensitivity to the effects of mutation that facilitates rapid evolution to novel states.

Modeling control strategies of respiratory pathogens.

Effectively controlling infectious diseases requires quantitative comparisons of quarantine, infection control precautions, case identification and isolation, and immunization interventions. We used contact network epidemiology to predict the effect of various control policies for a mildly contagious disease, such as severe acute respiratory syndrome, and a moderately contagious disease, such as smallpox. The success of an intervention depends on the transmissibility of the disease and the contact pattern between persons within a community.

Distributions of beneficial fitness effects in RNA.

Beneficial mutations are the driving force of evolution by natural selection. Yet, relatively little is known about the distribution of the fitness effects of beneficial mutations in populations. Recent work of Gillespie and Orr suggested some of the first generalizations for the distributions of beneficial fitness effects and, surprisingly, they depend only weakly on biological details.

Dietary Reference Intakes: development and uses for assessment of micronutrient status of women--a global perspective.

This paper reviews the process of developing the Dietary Reference Intakes (DRIs) and provides a synopsis of the micronutrient status of women worldwide. At a 1993 symposium held by the Food and Nutrition Board (FNB) of the Institute of Medicine (IOM), it was decided that the Recommended Dietary Allowances (RDAs) would be replaced by the DRIs, which would address several issues that the RDAs did not, including chronic disease risk reduction, upper levels for nutrients where toxicity data existed, and the possible health benefits of some food components that did not meet the traditional definition of a nutrient. Another important distinction is that because the DRIs are comprised of 4 reference values -the Estimated Average Requirement (EAR), RDA, Adequate Intake (AI), and a tolerable Upper Level (UL) -and not a single reference value like the previous RDAs, they could be used to differentiate planning from diagnosis or assessment.

Network theory and SARS: predicting outbreak diversity.

Many infectious diseases spread through populations via the networks formed by physical contacts among individuals. The patterns of these contacts tend to be highly heterogeneous. Traditional "compartmental" modeling in epidemiology, however, assumes that population groups are fully mixed, that is, every individual has an equal chance of spreading the disease to every other.

The robustness of naturally and artificially selected nucleic acid secondary structures.

Thermodynamic stability and mutational robustness of secondary structure are critical to the function and evolutionary longevity of RNA molecules. We hypothesize that natural and artificial selection for functional molecules favors the formation of structures that are stable to both thermal and mutational perturbation. There is little direct evidence, however, that functional RNA molecules have been selected for their stability.

Greed, death, and values: from terror management to transcendence management theory.

Research supporting terror management theory has shown that participants facing their death (via mortality salience) exhibit more greed than do control participants. The present research attempts to distinguish mortality salience from other forms of mortality awareness. Specifically, the authors look to reports of near-death experiences and posttraumatic growth which reveal that many people who nearly die come to view seeking wealth and possession as empty and meaningless.

Aptamer database.

The aptamer database is designed to contain comprehensive sequence information on aptamers and unnatural ribozymes that have been generated by in vitro selection methods. Such data are not normally collected in 'natural' sequence databases, such as GenBank. Besides serving as a storehouse of sequences that may have diagnostic or therapeutic utility, the database serves as a valuable resource for theoretical biologists who describe and explore fitness landscapes.

Epidemiology, hypermutation, within-host evolution and the virulence of Neisseria meningitidis.

Many so-called pathogenic bacteria such as Neisseria meningitidis, Haemophilus influenzae, Staphylococcus aureus and Streptococcus pneumoniae are far more likely to colonize and maintain populations in healthy individuals asymptomatically than to cause disease. Disease is a dead-end for these bacteria: virulence shortens the window of time during which transmission to new hosts can occur and the subpopulations of bacteria actually responsible for disease, like those in the blood or cerebral spinal fluid, are rarely transmitted to new hosts. Hence, the virulence factors underlying their occasional pathogenicity must evolve in response to selection for something other than making their hosts sick.

Mechanical instability as a cause of gait disturbance in high-grade spondylolisthesis: a pre- and postoperative three-dimensional gait analysis.

Mechanical instability of the spinopelvic junction is a suspected cause of abnormal gait in high-grade spondylolisthesis. Computerized three-dimensional gait analysis was performed on a 10-year-old with grade III spondylolisthesis at L-5. Preoperatively, the gait pattern was characterized by posterior pelvic tilt, decreased hip flexion, increased knee flexion, and decreased stride length and walking speed.