Computer program determines exact two-sided tolerance limits for normal distributions

Computer program determines by numerical integration the exact statistical two-sided tolerance limits, when the proportion between the limits is at least a specified number. The program is limited to situations in which the underlying probability distribution for the population sampled is the normal distribution with unknown mean and variance

Predicting dynamic performance limits for servosystems with saturating nonlinearities

A generalized treatment for a system with a single saturating nonlinearity is presented and compared with frequency response plots obtained from an analog model of the system. Once the amplitude dynamics are predicted with the limit lines, an iterative technique is employed to determine the system phase response. The saturation limit line technique is used in conjunction with velocity and acceleration limits to predict the performance of an electro-hydraulic servosystem containing a single-stage servovalve. Good agreement was obtained between predicted performance and experimental data

Re-examination of the Effects of Food Abundance on Jaw Plasticity in Purple Sea Urchins

Morphological plasticity is a critical mechanism that animals use to cope with variations in resource availability. During periods of food scarcity, sea urchins demonstrate an increase in jaw length relative to test diameter. This trait is thought to be reversible and adaptive by yielding an increase in feeding efficiency. We directly test the hypotheses that (1) there are reversible shifts in jaw length to test diameter ratios with food abundance in individual urchins, and (2) these shifts alter feeding efficiency. Purple sea urchins, Strongylocentrotus purpuratus, were collected and placed in either high or low food treatments for 3 months, after which treatments were switched for two additional months between February and September, 2015 in La Jolla, CA (32.8674°N, 117.2530°W). Measurements of jaw length to test diameter ratios were significantly higher in low compared to high food urchins, but this was due to test growth in the high food treatments. Ratios of low food urchins did not change following a switch to high food conditions, indicating that this trait is not reversible within the time frame of this study. Relatively longer jaws were also not correlated with increased feeding efficiency. We argue that jaw length plasticity is not adaptive and is simply a consequence of exposure to high food availability, as both jaw and test growth halt when food is scarce

Summer Ephemeroptera, Plecoptera, and Trichoptera (EPT) Species Richness and Community Structure in the Lower Illinois River Basin of Illinois

Ephemeroptera, Plecoptera, and Trichoptera (EPT) species richness is useful for monitoring stream health, but no published studies in Illinois quantitatively document EPT richness or assemblage structure. The objectives of this study were to characterize adult EPT richness and structure and relate these to relative water at eight stream sites (160-69,300 km3 area) in the lower Illinois River Adults were ultra-violet light trapped in June, July, and August 1997. Nutrient enrichment by nitrate and nitrite nitrogen was strongly evident, in smaller drainages, while critical loss of stable habitat was observed in water bodies. Seventy EPT species were identified from 17,889 specimens. Trichoptera were by far the most speciose (41 species), followed by Ephemeroptera (26), and Plecoptera (3). Caddisflies also dominated species richness across sites, contributing 18.0 of the average 28.9 total EPT species collected. Site EPT richness varied significantly (F =5.51, p 0.003, df 7), with smaller drainages supporting greater richness, generally. Differences were also evident for months (F = 21.7, p =0.0001, df =2), with June being lower (11.8 average) than either July (20.6) or August (18.1) values. Hilsenhoff biotic index (HBI) scores did not vary significantly across sites (F 0.7, p =0.7, df =7), but were different across months (F =5.4, p 0.02, df 2). June (4.23) and July (4.53) means were not different, but both were lower (of better quality) than August (5.33) scores. The relationship of EPT to HBI scores was not investigated statisti- cally due to problems of sample size and interdependance of monthly sam­ ples, but graphical analysis no consistent relationship. This sug- gested a decoupling of the the EPT and implied that the gain in taxonomic resolution achieved by adults outstripped the resolution of the HBI. Use of the HBI to characterize adult aquatic insect communities is discouraged. New state records and extensions for Ephemeroptera and Trichoptera are presented and loss of sensitive Plecoptera in the drainage is discussed

Understanding Circadian Regulation of Carbohydrate Metabolism in Arabidopsis Using Mathematical Models

C3 plants assimilate carbon by photosynthesis only during the day, but carbon resources are also required for growth and maintenance at night. To avoid carbon starvation, many plants store a part of photosynthetic carbon in starch during the day, and degrade it to supply sugars for growth at night. In Arabidopsis, starch accumulation in the day and degradation at night occur almost linearly, with the shape of this diel starch profile adaptively changing to allow continuous supply of sugar even in long-night conditions. The anticipation of dawn required to ensure linear consumption of starch to almost zero at dawn presumably requires the circadian clock. We review the links between carbon metabolism and the circadian clock, and mathematical models aimed at explaining the diel starch profile. These models can be considered in two classes, those that assume the level of available starch is sensed and the system ensures linearity of starch availability, and those in which sugar sensing is assumed, yielding linearity of starch availability as an emergent property of sucrose homeostasis. In the second class of model the feedback from starch metabolism to the circadian clock is considered to be essential for adaptive response to diverse photoperiods, consistent with recent empirical data demonstrating entrainment of the circadian clock by photosynthesis. Knowledge concerning the mechanisms regulating the dynamics of starch metabolism and sugar homeostasis in plants is required to develop new theories about the limitations of growth and biomass accumulation

Notes on drift theory

It is shown that there is a simpler way to derive the average guiding center drift of a distribution of particles than via the so-called single particle analysis. Based on this derivation it is shown that the entire drift formalism can be considerably simplified, and that results for low order anisotropies are more generally valid than is usually appreciated. This drift analysis leads to a natural alternative derivation of the drift velocity along a neutral sheet

Computational Methods and Results for Structured Multiscale Models of Tumor Invasion

We present multiscale models of cancer tumor invasion with components at the molecular, cellular, and tissue levels. We provide biological justifications for the model components, present computational results from the model, and discuss the scientific-computing methodology used to solve the model equations. The models and methodology presented in this paper form the basis for developing and treating increasingly complex, mechanistic models of tumor invasion that will be more predictive and less phenomenological. Because many of the features of the cancer models, such as taxis, aging and growth, are seen in other biological systems, the models and methods discussed here also provide a template for handling a broader range of biological problems