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Forty-six randomly selected primiparous mothers were observed when breast-feeding or bottle-feeding on the 2nd, 4th, and 42nd days post-partum. All mothers were living under socially stable conditions, and had no complications during delivery. The mother's behavior during nursing was classified according to proximity to the child into the classes proximal behaviors (“cloth contacts” and “skin-to-skin contacts”), and proximo-distal behaviors (behaviors including both proximal and distal components). An unequivocal trend was observed. In fact, all 46 mothers showed a decrease in the number of proximal contacts during the first six weeks after partus. The proportion of proximo-distal contacts increased from 30% during the first week to 60% during the sixth week. This increase may have an important function for introducing distal elements into the newborn's relation with the mother.

One of the most important problems of the modern triboengineering materials science is the development and study of new self-lubricated materials for sliding electrical contacts. The establishment of principles of self-lubricated conducting materials is based on a deep knowledge of the phenomena occurring during their frictional interaction with the counterface. It is believed that the efficiency of sliding contacts is closely related to the ability of materials to form transfer films on the counterface. The present paper shows that when metal-polymer materials are used as contacts, the contact behavior depends on the processes of generation and regeneration of transfer films. A new technique, designed and applied for the examination of surface layers of the materials, together with known procedures allowed a comparison of surface properties, such as electrophysical and topographic, of the metal-polymer friction transfer films with those formed by conventional compounds. The kinetics of the metal-polymer ...

Air pollution contributes to the degradation of the reliability of telephone switching relays. To study pollution effects on the French crossbar telephone exchange system we conducted three studies: first, atmospheric analysis in some telephone central offices; second, surface analysis of contacts from telephone exchanges; and, third, laboratory simulation tests in order to accelerate the harmful effects of natural exposure. This paper reports the methods used, and gives some results on the 'behavior of connectors and relays in some aggressive atmospheres.

The elements of a body whose stresses or strains or their combinations are governed by prescribed conditions are termed conditional joints. During a loading process, new contacts develop (locking of gaps) or existing connections become ineffective (plastification), causing physical nonlinearity of the body. This ideal elastic-plastic and locking behavior of materials can be described by “polygonal” constitutive laws and related nondifferentiable strain and complementary energy functional. Using convex analysis and the notion of subdifferential, constitutive laws of nondifferentiable but convex energy functionals with corresponding variational principles can be discussed generally. This paper combines conditional joints and the subdifferential connection of mathematics, including elastic, plastic, hardening, locking, and contact behavior of materials.

Nursing and mother-infant distance were observed in three orangutans, two gorillas, one chimpanzee and four humans. All four species showed periods of a recurrence of greater time spent nursing and in contact with the mother. The initial regressive or reattachment period occurred similarly in all four species at between 6–12 months of age. An orangutan observed for two years showed a second period at 19–21 months. Other studies of weight gain in the three ape species coincidently peaked at the same time. When estimated peaks of individuals of each species were summed, the resulting graphs showed a differentiation of species rates of development. Gorillas developed most rapidly, orangutans developed most slowly, while chimpanzees and humans developed within the middle range.

A cross-sectional epidemiological survey on Schistosoma haematobium infection was carried out in a small community in the coastal area of Kenya. From the 1, 206 registered inhabitants, 853 urine specimens were examined. The overall prevalence and intensity of infection were 68.2 percent and 50.0/hour respectively. Some demographical and geographical differences of infection were analyzed. The profile of age-related distribution showed sexual differences in the prevalence and intensity of infection, the prevalence of heavy infection (>1, 000/hour) and the prevalence of gross hematuria. Those of females are higher than those of males especially after adolescence. This is probably due to the difference in water contact behavior. The marked higher prevalence and intensity of infection were observed among people who lived along the branch of a main river than those who lived along the main river. The difference might be due to the different degree of contamination in the rivers. There was no difference in prevalence and intensity of infection among the three main tribes.

The state-of-the-art of contact formation on n and p-type cadmium telluride is discussed in this paper. We summarize the main surface properties, which influence the contact behavior, and the various technologies, which have been used to fabricate ohmic and rectifying contacts on CdTe. In this way MS and MIS structures, p-n junctions, and heterojunctions have been considered. In all cases we indicate the advantages and disadvantages of the electrical behavior of the devices.

Frictionally heated sliding contact similar to that of a dry or boundary-lubricated seal is investigated, regarding an instability in contact pressure. Above a critical sliding speed, this phenomenon causes the nearly uniform initial distribution to become one with localized high pressure patches. The threshold of instability is shown to be strongly influenced by wear rate. Above a critical wear w* contact is stable irrespective of sliding speed. Two dimensionless groups Vc/Vc*, a dimensionless sliding speed, and w/w*, a dimensionless wear rate, are shown to control contact behavior under the conditions of the model investigated. The effects of normal displacements, at the interface, caused by frictional shear stress, were also investigated and found to be of minor importance. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Miami Beach, Florida, October 21–23, 1975

A Project intended to increase client-contacting behavior on the part of 16 real-estate sales persons was described. Both contacts with prospective (initials) and with established clients (followups) were targeted for change. During a 20-week baseline, agent self-reports were used as a basis for posting weekly charts of contact behavior together with measured sales and listing performances. A conjunctive token-reinforcement procedure involving both contact behaviors was introduced during a 15 week intervention phase. For all agents as a group, a sustained increase in both behaviors was noted during this phase. Additional analyses revealed, however, that for low baseline performers, the intervention effect was only short-lived. During a subsequent three-week prewithdrawal stage, the increased behavion from the previous phase reverted nearly to baseline levels, despite the continued intervention, in response to instructions that program withdrawal was imminent. Contact behaviors further declined to below ba...

The social huddling and contact behavior of 5- to 7-day-old Norway rat pups was recorded in a series of experiments testing for the effects of social and environmental variables on huddling preferences. Both males and females huddled more with opposite-sex littermates compared to same-sex littermates or strange agemates from a different litter. Subjects were least likely to huddle with strange pups of the opposite sex. These data were discussed in terms of sex-specific adult social preferences. Also, sex preferences in the huddling behavior of male and female pups were found to be limited by cage bedding conditions. Preferences for huddling with opposite- over same-sex littermates were found when observations took place on bedding holding the odor of a strange dam with litter. A preference for the same-sex littermates was found for the bedding condition holding the odor of the home cage. These results were discussed in terms of the control of ultrasonic pup vocalizations by conspecific odor conditions.

The low-load, dry circuit contact properties of typical tin plates have been investigated, with emphasis on the spherical indentor/flat configuration found in many connectors. The resistance was determined as a function of applied load for a variety Of plate combinations, as well as after exposure to a moist SO 2 accelerated corrosion test. The results Showed, among other things, that the contact behavior is critically dependent upon the properties of both halves of the contact system and that flats plated with matte tin behave better than those plated with bright tin.

A cross-fostering paradigm was used to determine effects of early social environment on subsequent parental behavior of meadow voles ( Microtus pennsylvanicus ). Meadow-vole pups were fostered to either meadow-vole parents (in-fostered young) or prairie-vole parents (M. ochrogaster ; cross-fostered young). Young reared by prairie-vole parents received more parental contact than pups fostered to meadow-vole parents. At 60 days of age, nonlittermates of the same rearing condition were paired for breeding, and interactions between pairs and their litters were recorded from below large table-like pens. Postpartum nest cohabitation by males and females was observed in four of eight cross-fostered pairs; members of all eight in-fostered pairs displayed separate nesting. Cross-fostered females spent more time in the nest and exhibited more brooding, nursing, and pup grooming than in-fostered females. Cross-fostered males often entered the natal nest and engaged in more pup contact behavior than in-fostered males. In general, nonsocial behavior was unaffected by rearing condition. These results suggest that development of parental behavior in the meadow vole is subject to influence by characteristics of the early environment.

Huddling, or clumping behavior, begins in the litter situation and persists throughout the adult life of the rat (Rattus norvegicus). In pups, as in adults, the behavior provides a metabolically important means of reducing heat loss. The sensory stimuli that elicit, direct, and maintain huddling in developing rat pups (5-20 days of age) were studied in a standardized testing situation by using long-term time-lapse video observations. All pups huddled with a single, immobile sibling. A loop of warm tubing also elicited huddline. However, it appears that other, nonthermal cues can elicit huddling, since a dead, ambient-temperature pup was a sufficient stimulus for the behavior. Disruption of normal olfactory input by intranasal infusion of zinc sulfate interfered with the maintenance of contact. In addition, two kinds of tactile stimulus, vertical contours and furry "comfort" cues, as well as photic responses appeared to participate in the mediation of huddling. Huddling in the altricial rat is under multisensory control, although the number of cues used by pups for huddling appears to increase with age.

This paper presents some further results of the IBM Electrical Contacts Field Program, introduced previously. The degradation of contact materials over a period of time at six field sites is described as a function of atmospheric pollutants. The results of short-term laboratory exposures of some of these metals in tarnishing environments are compared and contrasted with the field results. Methods that have been found to significantly reduce the extent of tarnish formation on electric contact materials or to reduce the effect of such tarnish products on contact behavior are discussed.

When palladium or platinum-family metal contacts are operated in an environment which includes organic vapors, the performance of the contacts may be seriously degraded. If the contacts open and close currents, the contact erosion may be increased enormously. On the other hand, if the contacts merely prepare the circuit and do not directly open or close the current flow, no erosion will take place. The contacts may then fail to conduct the circuit current satisfactorily, because of the formation of an insulating polymer-like film. This latter type of failure has been the subject of extensive studies at Bell Telephone Laboratories for the past several years and is the subject of this article. These studies have yielded a new understanding of the contact problem and resulted in certain changes in relay contacts to improve their performance under service conditions.

Contact behavior of presumptive mesodermal cells taken from normal amphibian embryos, hybrid embryos, and hybrid embryos arrested at gastrulation was investigated. Normal cells have a high ability to flatten on a glass substratum and reaggregate. Cells from a viable hybrid which shows some abnormalities in invagination have an intermediate ability to flatten on a glass substratum and an undiminished ability to reaggregate. Cells from three different types of hybrid embryos arrested at gastrulation have a low ability to flatten on a glass substratum and reaggregate. The implications of these results for hypotheses concerning mechanisms of morphogenetic cell movements are discussed.

The contact behavior of metal surfaces has been studied by determining the normal approach of two contacting surfaces subjected to a normal load. By considering certain contact situations, the effects of such factors as the mode of asperity deformation, the population of asperities and their orientation over the surface have been examined. It has been demonstrated that the contact behavior is significantly influenced by these factors and that certain modifications should be introduced to the relevant theoretical treatment.

When presentation of a retractable lever always preceded food delivery, rats licked or gnawed the lever. They also approached but seldom orally contacted a lever signaling brain-stimulation reinforcement; instead, subjects sniffed, pawed, or "explored" the lever. Therefore, a Pavlovian conditioned stimulus evoked directed skeletal responses whose specific form depended on the forthcoming unconditioned stimulus.

Ten thousands of honey bees make a colony and live socially. To maintain their society, they have developed various communication systems such as famous waggle dances, vibration signals and various pheromones. Worker honey bees engage age-related divisions of labor, such as nursing, nest building, patrolling, nectar preserving and foraging. So, they would need different information for their labor. We observed contact behaviors of bees in an artificial small box to study age-related communication change. Two worker bees from four groups (one day aged young bees, 5 days aged nursing bees, 15 days aged nectar preserving bees and 20 days old foraging bees) were introduced in a box and contact behavior was registered. Then in a set of three bees, the behavior of one object bee to other bees was observed. The results showed

Rats were exposed to a differential conditioning procedure in which one lever-stimulus predicted a food UCS (for one group) or a brain-stimulation UCS (for 2 other groups) while a second lever-stimulus was explicitly unpaired with the UCS. A fourth group received differential training where one lever-stimulus signalled food and the other brain-stimulation. The animals reliably approached and contacted the predictive stimuli with there being no significant difference in this tendency between groups. There was, however, a significant difference in the form of the stimulus contact behavior as a function of the quality of the UCS. Rats gnawed the stimulus when the UCS was food but sniffed it when the UCS was brain-stimulation. This difference was independent of the level of food deprivation and occurred within animals in the group which received both kinds of UCS. The results indicate that properties specific to the reinforcer are important in response performance. Such effects should be considered in the analysis of performance on instrumental tasks, especially when concern is focussed on performance differences which are correlated with qualitatively different rewards.

Rat pups of all ages huddle with conspecifics, but the senosory control of contact behavior changes ontogenetically. Thermal cues control huddling until about Day 15, at which time species' odors become the dominant stimulus. The present experiments indicate that the filial response to conspecifics is dependent on olfactory experience. A synthetic chemical scent was added to the smells of the dam from Day 1 to Day 20 postpartum. Standardized videographic tests were used to assess the development of huddling preference. Preferences for nest-typical smells emerged by Day 15 in pups from both scented and nonscented litters. Pups from scented nests preferred to huddle with a scented stimulus rat, whereas control pups preferred a nonadulterated rat stimulus. Additional testing indicated that the affiliative preferences were specific to rearing odor and were not based on decreased aversion to test scents, or on disrupted olfactory discrimination. The ontogeny of species-typical contact behavior is discussed in terms of the induction of a perceptual preference that is based on early odor stimulation.

Static indentation laws for laminated composite thin shells and a rigid ball are proposed in this research. The contact behaviors of the rigid ball and target shells are divided into three stages i.e., the loading, unloading and reloading stages. While a 2.5 power is suggested to use in unloading stage, it is found that Hertzian type 1.5 power law is adequate to represent the loading and reloading paths. The effect of the curvature is considered by imposing an unknown function in force-indentation equation for describing the contact behavior at loading stage. This unknown function which characterizes the curvature effect is obtained by modifying the Hertzian law. Once this unknown function is determined, the unloading and reloading equations could be derived from it.

Norway rat pups, 15 days of age and older, huddle preferentially with members of their own species. This normal filial response can be reassigned, however, by altering the olfactory characteristics of the mother. The present series of experiments was designed to isolate those aspects of maternal stimulation that establish the rial huddling preferences of rat pups. Results of two-choice huddling tests indicated that daily, 4-hr exposures to a perfumed foster dam induced fiial preferences for odors associated with maternal care. Similar effects were also achieved with equal amounts of “mere exposure” (familiarization) to odors. Different kinds of odor-experience pairings were evaluated with a within-subject regime of alternating, daily exposures. It was found that preferences induced by maternal contact are stronger than those resulting from familiarization. We rejected the hypothesis that the nursing relationship is a necessary or contributory factor in the establishment of the rat’s filial attraction; preferences for odors associated with a nonlactating foster mother were as strong as those derived from maternal contact that included nutritive nursing. Contact interactions with an inanimate, warm, scented tube induced preferences as strong as those induced by maternal care. It was concluded that thermotactile stimulation during mother-young interactions induces olfactory preferences in the weanling rat. The normal natal environment of the newborn rat (Rattus norvegicus) consists of the huddle of littermates and the mother. For several weeks after birth, the pups reside in the maternal nest, where they receive periodic bouts of nutritive contact and stimulation from the dam (Ader & Grota, 1970; Leon, Croskerry, & Smith, 1978). It is from this natal environment that the rat pup emerges just a few weeks postpartum as an independent but highly gregarious creature. The rat’s affiliative bonds can be seen in the strength and specificity of its social contact or huddling behavior, which persists as a major activity throughout life. Beginning at about 2 weeks of age, the rat pup normally displays a robust preference for huddling with species members (conspecifics) over other acceptable huddling stimuli (Alberts & Brunjes, 1978). The conspecific preference is based on species odors (Alberts, 1978b; Alberts & Brunjes, 1978). Younger pups also huddle vigorously, but they are dominated by thermal stimuli and appear relatively indifferent to olfactory cues. Olfactorily guided filial huddling emerges by Day 15 (Alberts & Brunjes, 1978). Throughout this paper, the term “filial huddling” will be used to denote contact behavior that is

Social isolation for 7 days increases the frequency of social interactions of rats, when they are tested with non-isolated partners in dyadic encounters. Subcutaneous administration of beta-endorphin enhances the social interactions of the isolated animals. Especially contact behavior, which includes crawl over, mounting and social grooming is stimulated by beta-endorphin, whereas social explorative behavior and approaching/following are less or not changed by peptide treatment. Already 10 ng/kg of the peptide increases the social interactions, especially social contacts of the rats. Treatment with naltrexone does not interfere with the social interactions of the isolated animals, but completely antagonizes the beta-endorphin-induced increase of social behavior, suggesting that this effect of beta-endorphin is mediated by opiate receptor systems. It is postulated that beta-endorphin modulates close and intimate social contacts probably by its reward-inducing properties.

Man communicates with his fellow man, with speech but also with a number of expression-movements. Whether these signals belong to an innate repertoire of motor patterns which are not learned is a point of controversy. Gehlen is of the opinion that, except perhaps for a few reflexes of the newborn, there are no innate behavior patterns in man [14]. A similar view was expressed by Montagu [21], while Birdwhistell specifically emphasized that there are no inherited facial expressions and gestures in man, and that therefore differences are found transculturally [4,5]. Birdwhistell is very firm about this point, although in his publications concerning cross-cultural evidence he only makes statements.

Chimpanzees are apparently unable to swim, a fact which may be accounted for by a low ratio of fat to muscle and a low specific gravity. A survey of field studies of wild chimpanzees indicates that they have very little contact with water. In contrast, chimpanzees in captivity frequently drink standing water, possibly because their diet is low in water content. Two of the semi-free-ranging chimpanzees observed in this study would immerse themselves to waist-level in moat water, replacing former behavior patterns of water avoidance.

I have been concerned with social relations between social groups of rhesus monkeys (Macaca mulatta). My studies have a distinct relationship with the major topics of the first two sessions of the Symposium, even though spatial parameters per se have not been the data of choice; instead, social interactions have been recorded.

The maintenance process rail milling and the rolling contact behavior of a milled rail are analyzed in detail. By using commercial finite element programs the milling process and the rolling-sliding contact of a wheel on a milled rail are simulated with 3D and 2D methods. These results are compared to experimental results and metallographic investigations of a milled rail after an actual milling process and after milling tests that were done in track together with a European infrastructure manager (IM). A satisfying agreement is shown by comparing the obtained numerical results with the experimental results and metallographic investigations.

The plane-strain contact problem of an elastic half-space indented by a nominally flat rigid surface having a finite number of regularly spaced cylindrical asperities is investigated using the finite element method to gain an understanding of the interactions in multi-asperity contacts. The significance of the number and spacing of asperities on the contact behavior at the center and edges of the interfacial region is examined. Subsurface stress fields of multi-asperity contacts are presented for various asperity distributions and indentation depths. Asperity interaction effects are quantified in terms of representative parameters, such as the maximum contact pressure, normal load, and maximum von Mises equivalent stress, normalized with similar quantities of the single-asperity contact problem. These nondimensional parameters are principally affected by the spacing and radius of asperities and secondarily by the indentation depth. Significant deviations from the single-asperity Hertzian solution may be encountered, especially in the neighborhood of asperity contacts, because of the unloading and superposition mechanisms which depend on the distance and radius of asperities and indentation depth. The finite element results are in fair qualitative agreement with the phenomenological behavior and analytical predictions.

The dynamics of chromatin folding has an important role in regulating gene expression in higher eukaryotes. Detailed studies of several model loci, such as beta-globin, have shown that the formation of loops mediated by the interaction between specific regulatory elements that are located hundreds of kilobases away is crucial in gene control. This observation gives rise to an important question: how can a set of widely spaced elements communicate in order to regulate a specific target gene.Recently a computational model has been proposed by Mukhopadhyay et al to explain the formation of long-range chromatin loops. This model is based on attractive nucleosome-nucleosome interaction, allowing the monomers of a chromatin polymer to stick to each other temporarily when in the vicinity of each other. This model shows the enhanced long range contact behavior consistent with shown in recent studies and predicts suppression of pseudoknot formation in chromatin folding. However, it remains to be understood why the chromatin polymer model behaves this way. To answer this question, we propose to look at the structure of the temporarily collapsed configurations of a polymer in certain ranges of lengths and attraction strengths. In particular, our aim is to calculate the crossover scale between the collapsed polymer at longer distance and the folded branched polymer at shorter distance. Such theoretical predictions from a polymer model combined with simulations of polymer conformations (both lattice polymer models and bead-spring models), would tell us whether, in the realistic model, there are certain parameter combinations that has to be fine-tuned to get the suppression of pseudoknots. We hope this study leads to a better understanding of the role of non-specific interactions of the polymer physics of chromatin.