PubMed Health⌕ Search

Biomedical subjects

P E Waggoner

Publications and source records attributed to P E Waggoner.

At least 19 recordsLinked to original sources
PubMed2002

A framework for sustainability science: a renovated IPAT identity.

Learning actors' leverage for change along the journey to sustainability requires quantifying the component forces of environmental impact and integrating them. Population, income, consumers' behavior, and producers' efficiency jointly force impact. Here, we renovate the "IPAT Identity" to identify actors with the forces. Forcing impact I are P for population, A for income as gross domestic product (GDP) per capita, C for intensity of use as a good per GDP, and T for efficiency ratios as impact per good. In the "ImPACT Identity," parents modify P, workers modify A, consumers modify C, and producers modify T. Because annual percentage changes in component forces add to a change in national impact, actors' leverage is reflected transparently in consistent units of annual percentage changes that can be compared from force to force. Examples from energy and food, farming and manufacturing, and steel and water show that declining C, called dematerialization, can temper the sustainability challenge of growth (P x A), and that innovation or efficient technology that lowers T can counter rising consumption (P x A x C). Income elasticity can accommodate connections between income and other forces. From rates of change of forces, the identity can forecast impacts. Alternatively, by identifying the necessary change in forces to cause a projected impact, ImPACT can assay the likelihood and practicability of environmental targets and timetables. An annual 2-3% progress in consumption and technology over many decades and sectors provides a benchmark for sustainability.

Agriculture↗
PubMed1981

Lesion distribution, multiple infection, and the logistic increase of plant disease.

The lesions of few of the 112 observed cases of plant disease were randomly distributed; most were fitted by the negative binomial function with exponent approximately 1. The proportion of healthy hosts generally equaled the frequency of zero in the negative binomial. The same course of an epidemic is calculated for the logistic increase of infected plants or for plants infected by propagules produced in proportion to lesions and distributed with exponent equal 1.

Journal Article↗
PubMed1979

Secular change in the variability of temperature.

The mean temperatures for January, April, summer and October at New Haven, Connecticut, for 1781-1970 were analyzed for evidence of a secular change in several indices of variability. The January-July difference decreased significantly. Although the standard deviation (SD) of the summer temperature within decades decreased significantly, the SDs of January, April, and October did not, and none of the SDs were correlated with means. The SD about trends within decades was not correlated with the magnitude of the trends except in April. There was no significant trend in the January-to-January persistence during the 19 decades.

Journal Article↗
PubMed1976

Water uptake and water diffusivity of seeds.

When pea (Pisum sativum) seeds were wetted, a sharp front separated the wet and dry portions, the seeds swelled, and the water content in the wetted portion continued to increase for a long time. A model was proposed and tested that takes into account these three characteristics and in particular does not postulate a constant diffusivity. The parameters of the model are simply the rate of penetration of the wetting front and a swelling factor.

Journal Article↗
PubMed1975

Water uptake, diameter change, and nonlinear diffusion in tree stems.

A diffusion model for phloem swelling and contraction is proposed in which the rate of water movement changes markedly with moisture content. Good agreement between the actual swelling of the phloem of cotton stems and that predicted by the model was obtained. This result implies that water moves more readily into the phloem when it becomes wetter. This model also explains the lag of shrinkage of pine stems behind the water potential of the foliage and predicts that the lag is related to the thickness of the phloem.

Journal Article↗
PubMed1972

Boundary Layer Resistance and Temperature Distribution on Still and Flapping Leaves: II. Field Experiments.

The forced convection of heat from reed (Phragmites communis) leaves was observed in their natural environment. The leaves were painted with liquid crystals, which displayed or indicated their temperature without any interference with natural air flow. Temperature differences as large as 15 C were observed between the leading and trailing edges of the nontranspiring, painted leaves. The turbulence of the natural wind decreased the boundary layer resistance around the leaf to about 40% of the resistance in a laminar steady wind.

Journal Article↗
PubMed1971

Boundary layer resistance and temperature distribution on still and flapping leaves: I. Theory and laboratory experiments.

If the evaporation is uniform on a flat exposed leaf, forced convection will also be nearly uniform, and the leaf temperature will vary with the square root of the distance from the leading edge. Then the resistance expressed in terms of the proper, i.e., average, temperature has the same value as the resistance of a leaf at uniform temperature. Compared to a steady laminar flow, the turbulence of a realistic wind decreases the resistance by a constant factor of about 2.5. The same constant factor was observed whether the leaf was flapping or not, when the wind velocity was not too low.

Journal Article↗
PubMed1970

Ozone uptake by bean leaves.

The removal of ozone from the air by bean leaves is regulated by the same factors that control the exchange of water vapor between leaves and the atmosphere.

Air Pollution↗
PubMed1970

Stomatal dimensions and resistance to diffusion.

In the past, relations of diffusive resistance to stomatal geometry have concerned circular pores or pores that are replaced by equivalent circles of the same area. We calculated the resistance for general shapes that include the realistic slit. The resistance comprises two terms. The first is an outer resistance that depends only on ventilation and leaf geometry and is independent of stomata. The second is an inner resistance and is a function of stomatal interference and of stomatal geometry only. If interstomatal spacing is at least three times stomatal length, interstomatal interference is negligible. The inner resistance can then be calculated by adding the resistance of the two ends and the throat of each stoma. In the case of an elongated stoma, the part of the diffusive resistance per square centimeter determined by stomatal geometry is [Formula: see text] where a, b, d, and n are the semilength, semiwidth, depth, and density of the stomata, and D is the diffusivity. This is the familiar Brown and Escombe result applied to slits.

Journal Article↗
PubMed1968

Effects of changing stomatal width in a red pine forest on soil water content, leaf water potential, bole diameter, and growth.

Spraying a 16 meter tall stand of red pine (Pinus resinosa Ait.) with 10(-3)m phenylmercuric acetate in early June and again in mid-July resulted in the water use between June 1 and October 25 being reduced by almost 10%. It was demonstrated that this was caused by an increase in the leaf resistance with partial stomatal closure, which reduced absolute water potential in the needles by 1 to 3 bars in the middle of the day. Smaller demands were made upon the reserves of water in the bole of the tree as shown by the smaller bole contraction in the treated trees. Although needle length and dry weight were unaffected by the spray, radial growth was reduced by approximately 32%. The dependence of leaf resistance on light intensity is shown, and its independence from leaf water potential discussed.

Journal Article↗
PubMed1966

Stomata and transpiration of droopy potatoes.

A diploid potato (Solanum tuberosum) mutant called droopy wilts easily. Excised leaves of the mutant lost weight, and hence water, more rapidly and had many more open stomata than leaves of a normal sibling. Further, the stomata of abnormal plants remained open in wilted leaves. When the stomata of the abnormal mutant were closed by a chemical spray, its excised leaves lost water no more rapidly than normal. Thus, the wilting of the mutant must be caused by wide stomata. The wilting of the abnormal leaves and the small dry weight of the plants indicate the advantage of the stomatal hydrostat in the normal plants.

Journal Article↗