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A new system is presented that allows a variable trephination of donor corneas for the preparation of corneal buttons used in penetrating keratoplasty. With the help of a computer-controlled positioning system that uses high-precision micropositioning elements (both translation and rotational stages) the donor cornea is removed, epithelial side up, in a fixation device in front of a focused excimer laser beam (ArF, lambda = 193 nm). User friendly computer software allows the surgeon to select a variety of parameters (diameter, shape, angle of trephination) of the corneal graft. Histological and electron microscopical data of human corneas trephined with this "Excimer Laser Corneal Shaping System" are presented.

We examined within- and between-group differences in aspects of feeding and nutrient intake among adult females of a single population of baboons (Papio cynocephalus) in Amboseli National Park, Kenya. Differences in time spent feeding, daily energy and protein intake and feeding efficiency (nutrient intake per minute spent feeding) reflected differences in resource base, reproductive condition and parity. Baboons that partially fed from a lodge garbage dump spent less than half the time feeding than those that were feeding totally in the wild. During this greatly reduced feeding time, the garbage-feeding group had a similar daily energy intake and only a slightly lower daily protein intake relative to wild-feeding baboons. Consequently, the feeding efficiency of the semi-provisioned baboons was appreciably higher than that of the non-provisioned baboons. For the totally wild-feeding baboons, samples were large enough to permit analyses of feeding time and nutrient intake during different reproductive states and parity. Females spent more time feeding and had higher daily energy and protein intake when they were pregnant or lactating than when they were sexually cycling. Nulliparous females spent more time feeding than their multiparous counterparts. The daily energy intake of nulliparous females was higher than that of their multiparous counterparts, but their daily protein intakes did not differ significantly. Pregnant or lactating and nulliparous females had higher feeding efficiency than their sexually cycling and multiparous counterparts. The two nulliparous females in the garbage-feeding group spent more time feeding but did not take in more energy or protein per day than their multiparous counterparts.

A simple model of the photosynthetic unit has been constructed and used for simulated Förster-type energy migration, fluorescence and intersystem crossing, in order to gain insight into the conditions that influence both the form and the lifetime of the fluorescence decay in vivo. The model consists of a two-dimensional random lattice with one central trap. The simulation was done by means of repetitive Monte Carlo-type computations. The results obtained show that the form of the decay curve changes from exponential to non-exponential, as the chlorophyll concentration (molecules/nm2) is increased. The fluorescence lifetimes (tau 1/e) were also found to decrease substantially with only slight increases inc concentration. At a concentration comparable to that of chlorophyll in the chloroplast, both the form of the fluorescence decay and the lifetime are in fair agreement with experiment in vivo. The reasons for non-exponentially of the decay as well as the properties of energy migration are discussed. Preliminary work involving the dependence of trapping rate on donor concentration is also presented.

In a longitudinal study of individually identified wild baboons in Amboseli National Park, Kenya, we collected data on physical development and reproductive maturation. Confirming and extending our earlier results, we demonstrated that the ratio of ages at which developmental milestones occur in the field as compared to those under extensive provisioning or in captivity were approximately 5:3. The age range for some developmental milestones was quite narrow and discrete, while for others there was considerable between-individual variability and more gradual changes. For infants, only the change from pink to gray of the paracallosal skin occurred within a brief age span. For older animals two important developmental events are readily identified and occur within a fairly narrow age range: Rapid enlargement of testes at 5 to 6 years for males and onset of menarche at 4 to 5 ½ years for females. In the present report, we considered some consequences of accelerated or delayed maturation. We further explored the need to employ different age-class criteria for different research problems., (Copyright © 1981 Wiley‐Liss, Inc., A Wiley Company.)

The fatal kidnapping of a 5-day-old baboon (Papio cynocephalus) in Amboseli National Park, Kenya, is described. Although pulling and rough handling of primate infants by nonmothers are frequently observed, records of fatal intragroup kidnappings are rare. In the instance described here, the mother, a healthy, primiparous female, did not retrieve the infant from the kidnapper, a higher-ranking juvenile female of the same group, until he died 3 days later, presumably from starvation or dehydration. This incident is compared with other fatal intragroup kidnappings in nonhuman primates and related to adaptive interpretations., (Copyright © 1987 Wiley‐Liss, Inc., A Wiley Company.)

We obtined data on body mass and growth rates for the immature members of two groups of wild baboons in Amboseli National Park, Kenya. Data were collected without feeding, trapping, or handling. The data were separated into cross-sectional and longitudinal components, allowing both the examination of body mass-age relationships and the calculation of growth rates for individuals. For animals less than three years old, body mass was wellperedicted from age by a linear model. Differences based on social group membership were small but consistent, and their origins are discussed. We detected no differences in body mass based on sex or on maternal dominance rank. For older juveniles, those three to seven years of age, a better fit was obtained from log of mass than by mass in a linear model. This was also true for the cross-sectional data set over the whole age range (zero to seven years). For older juveniles, samples were too small for quantitative analysis of differences based on sex, rank, or group membership, but trends in the data are indicated. Growth rates derived from repeat measures of body mass for 38 animals are presented and discussed.The growth rate values obtained in this study are consistent with data from cross-sectional studies of other wild baboon populations; these values for wild baboons are consistently one-half to one-third lower than growth rate values for well-provisioned captive baboons and equivalent to captive baboons fed a low-protein diet. Comparisons between primates and other mammals in the primate size range raise questions concerning ecological and behavioral constraints on primate growth rates; some possible mechanisms of constraint are suggested.

At maturity, female baboons in the Amboseli National Park of Kenya generally attain a rank position among adults near to that of their mothers. However, the age of a female's mother and the difference in ages between sisters also influence the rank acquisition process. These latter demographic variables, which are sensitive to changes in resource availability, may account for the close association both within and among primate species of specific patterns of rank organization and specific environmental conditions.

The mapping of retinal space onto the striate cortex of some mammals can be approximated by a log-polar function. It has been proposed that this mapping is of functional importance for scale- and rotation-invariant pattern recognition in the visual system. An exact log-polar transform converts centered scaling and rotation into translations. A subsequent translation-invariant transform, such as the absolute value of the Fourier transform, thus generates overall size- and rotation-invariance. In our model, the translation-invariance is realized via the R-transform. This transform can be executed by simple neural networks, and it does not require the complex computations of the Fourier transform, used in Mellin-transform size-invariance models. The logarithmic space distortion and differentiation in the first processing stage of the model is realized via "Mexican hat" filters whose diameter increases linearly with eccentricity, similar to the characteristics of the receptive fields of retinal ganglion cells. Except for some special cases, the model can explain object recognition independent of size, orientation and position. Some general problems of Mellin-type size-invariance models-that also apply to our model-are discussed.

Activity budgets and social aspects of feeding, among the adult females in a group of semiprovisioned baboons that fed from a garbage dump were compared with those of adjacent wild-feeding groups in Amboseli National Park, Kenya, during the dry seasons of 1984 and 1985. Statistically significant differences were found in time spent feeding, distance travelled, and the relationship between dominance rank and time spent feeding. The garbage-feeding animals fed for 20% of the time and rested for almost 50%, in contrast to approximately 60% and 10%, respectively, for the wild-feeding animals. Speed of travel, length of day-route, and home range size were greatly reduced for the garbage-feeding animals. Use of sleeping trees and day route were highly regular in contrast to the unprovisioned group. At the garbage dump, time spent feeding was correlated with dominance rank among the adult females of this study. This was not the case for feeding on wild foods. Human enriched food sources offer the opportunity to study limiting factors and relationships between ecology and behavior. However, these conditions lead to human-animal conflicts that may be to the animals' long-term detriment. Conservation and management implications are discussed., (Copyright © 1988 Wiley‐Liss, Inc., A Wiley Company.)

Fifteen patients were treated with low-dose (5 u/hour) insulin infusion, including 10 cases of ketoacidosis, 3 cases of hyperglycemia without acidosis in severely affected diabetics, and 2 cases with hyperosmolality. The treatment was successful in all cases. Insulin was infused at a constant rate, during 12 hours as a mean value. Blood glucose fell regularly and no hypoglycemia occured. Serum potassium varied within narrow limits, and no accident related to hypokalemia was observed. The correction of ketoacidosis was delayed, as compared to that of hyperglycemia. The two elderly patients with hyperosmolality recovered quickly and completely. The method of low-dose insulin infusion seems thus effective and easily applicable, at least in an intensive care unit. Our experience prompted us to increase (10 u/h) rather than to decrease the insulin infusion rate, with the aim to obtain a faster correction of ketoacidosis.

Formulas are developed for calculating the expected frequency of behaviour and of social interactions in each age-sex category or other class, particularly when the study population changes composition during the study, given the null hypothesis either of constant but unknown rates of behaviour that are independent of class, or of class-specific rates per individual.

Repeated censuses of a population of yellow baboons (Papio cynocephalus) in Amboseli National Park, Kenya, revealed a decrease from over 2,500 animals in 1963-1964 to 123 individuals in 1979, or from a density of about 73 to 1.8 baboons per km 2 over a 15-year period. Median group size decreased from 43 in 1964 to 27 in 1979. The largest and smallest groups declined the most; groups near the median have maintained fairly stable size and age distributions. The population seemed to have stabilized by 1983 at approximately 150 animals in six groups (median group size 28; density 2.2/km 2 ). Although baboon population and group size appeared to be stable during 1963-1964, the age distribution and demographic parameters (age-specific mortality and natality for one social group) during that year indicate that the population decline had already started. The rate of population decline was greatest in the 1964-1969 period and remained appreciable during the next 5 years. The decline of the baboon population was paralleled by that of other Amboseli savannah woodland mammalian species and took place during a period of very high mortality of fever trees (Acacia xanthophloea) and extensive invasion of the area by halophytes, a transition brought on by rising ground water and consequent elevation of the soil salinity zone. In this and several other primate populations, mortality of infants and juveniles appears to be the demographic variable most sensitive to environmental change., (Copyright © 1985 Wiley‐Liss, Inc., A Wiley Company.)

After definition of the 'rate of increase in urinary flow' uroflowmetry still does not seem to be of any value for the differentiation of abnormalities of micturition in women as a screening method. Correlating several parameters of uroflowmetry with different subjective and objective data and the final urodynamic diagnosis in 1113 sophisticated urodynamic studies we did not find a discriminatory value of any of the parameters described.

Female savanna baboons (Papio cynocephalus) had a longer postpartum amenorrhea and thereafter cycled longer before conceiving if their previous infant survived than if that infant died. Among mothers of surviving infants, differences in maternal care produced differences in age of weaning and age of independence but did not result in differences in interbirth intervals.