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PubMed2004

Spreading of families in cyclic predator-prey models.

We study the spreading of families in two-dimensional multispecies predator-prey systems, in which species cyclically dominate each other. In each time step randomly chosen individuals invade one of the nearest sites of the square lattice eliminating their prey. Initially all individuals get a family name which will be carried on by their descendants. Monte Carlo simulations show that the systems with several species (N=3,4,5) are asymptotically approaching the behavior of the voter model, i.e., the survival probability of families, the mean size of families, and the mean-square distance of descendants from their ancestor exhibits the same scaling behavior. The scaling behavior of the survival probability of families has a logarithmic correction. In case of the voter model this correction depends on the number of species, while cyclic predator-prey models behave like the voter model with infinite species. It is found that changing the rates of invasions does not change this asymptotic behavior. As an application a three-species system with a fourth-species intruder is also discussed.

Animals↗

PubMed1997

Gecko: a continuous 2D world for ecological modeling.

An individual-based simulation system, named Gecko, is presented for modeling multiple species at multiple trophic levels, on a spatially explicit, continuous two-dimensional landscape. Biologically motivated rules are specified at an individual level, and resulting behaviors are observed at an ecosystem level. Individuals are represented by circles with free range on a resource-producing plane. These circles grow allometrically with biomass of fixed resources. Resource acquisition behaviors include competition by area overlap for producers, and movement based on perception and intent. Individual-level energetics are explicitly modeled with inefficient assimilation, resource transformation, and allometrically specified metabolic costs. Individual growth and reproduction requires a history of successful resource acquisition. Terrestrial producer, herbivore, and carnivore species classes are included, extensible to further classes. A grassland food chain model of "plants," "grasshoppers," and "spiders" is used to demonstrate ecosystem-level results of given individual-level behaviors. Ecosystem-level behaviors include a trophic cascade of indirect carnivore-producer interaction effects; stable persistence of all populations; a near-realistic biomass pyramid; and spatial competition and coexistence of multiple producer species. Initial Gecko results show promise for application in both theoretical and natural ecosystem modeling.

Animals↗

PubMed1980

The Type A experience: occupational and life demands, satisfaction and well-being.

This study investigated the relationship of Type A behavior to occupational and life demands, occupational and life satisfactions, and emotional and physical health. Respondents were 127 senior administrators of correctional institutions. Data were collected via questionnaires and objective physiological and physical health assessments. Greater Type A's reported more occupational demands, more concrete stressful life events at work, greater interference of work with home and family life, and less marital satisfaction. But greater Type A's also reported more self-esteem at work, greater job involvement and organizational identification and greater life satisfaction. The latter findings highlight the resistance to behavior change by Type A men. Contrary to other studies, Type A behavior bore little relationship to emotional or physical health. Exploratory analyses relating Type A behavior to emotional and physical health did confirm previous findings when the older half of the sample (45 and above) was examined.

Adult↗

PubMed1982

Reproduction in Cheirogaleus medius.

The reproductive behavior of 20 captive Cheirogaleus medius was studied over two breeding seasons in 1980 and 1981. Seasonality, estrous cycle, sexual behavior, sexual maturity, and postpartum estrus are described. Reproduction of the different species of the family Cheirogaleidae as well as that of the Galaginae and Lemuridae is compared.

Animals↗

PubMed2005

B-type natriuretic peptide in athletes performing an Olympic triathlon.

AIM: Brain natriuretic peptide (BNP) is a cardioactive molecule produced in the myocardium. BNP is a sensitive marker of cardiac failure and its measurement in blood could be useful to the diagnosis and the treatment of this disease. Sporting activities, especially endurance ones, can induce cardiac problems, owing to the high workload for the myocardium during long and ultralong heavy effort. There are 2 papers describing the behavior of BNP in endurance events. BNP was elevated in marathoners, immediately after the race and also after 4 h. We studied the behavior of BNP in the triathlon, which is a complex sport characterized by 3 different activities (swimming, cycling, running). METHODS: We recruited 49 athletes, all males, except for 4 females; 2 athletes did not finish the race and were not included in the statistical analysis in 2 different competitions. In these subjects we measured BNP using an immunological method before and after a triathlon. RESULTS: No statistical significance between BNP values, before and after the triathlon, was found. CONCLUSIONS: We found no significant differences between pre- and postcompetition BNP values. Moreover, the range of values in both the blood drawings are similar of those of the general population, representing the biological variability of the analyte. The values in regularly trained athletes,, are not different from the general population and BNP is not modified by a triathlon, a typical endurance sport performance. We can underline that BNP increases in plasma are induced by heavy pathologies and are not influenced by physical activities, even strenuous ones.

Adult↗

PubMed1994

Cheating by students: findings, reflections, and remedies.

Cheating among students is surprisingly frequent and may be increasing. The 1991 study reported herein was prompted by an episode of cheating involving three second-year medical students at the University of New Mexico School of Medicine (UNM SOM) and was undertaken (1) to elicit the opinions of faculty members and students at that institution about whether selected descriptions of students' behaviors were unethical; (2) to document possible discrepancies between the opinions of the two groups concerning these behaviors; (3) to define the prevalence of unethical behavior among current students as estimated by faculty and students; and (4) to determine how best to approach future instances of unethical behavior. Questionnaires were distributed to all faculty and students. The first two parts, sent to both groups, concerned reactions to a series of described physician and student behaviors. For each described behavior, respondents were asked whether or not it was unethical and, for the described student behaviors, whether they had personal knowledge of such behavior by local medical students. The third portion of the questionnaire concerned faculty perceptions regarding students' behaviors over time. With the exception of the class involved in the cheating incident, faculty and students were surprisingly similar in their opinions regarding the ethical nature of the described behaviors. According to both faculty and students, there was a significant incidence ( > or = to 10% of the respondents) of unethical behavior at the school of medicine, most commonly in relation to cheating on examinations.(ABSTRACT TRUNCATED AT 250 WORDS)

Attitude↗

PubMed2004

Social competence in young children with inflicted traumatic brain injury.

As infants develop skills that allow for increasing independence in social and cognitive domains, they acquire the ability to identify goals, sequence behaviors to carry out goals, and to flexibly use strategies for attaining goals in both social and independent play contexts. Little is known about how brain injury in young children may disrupt the precursors to such executive processes. In this study, we examined social and cognitive competence in 25 infants ages 3 to 23 months who sustained moderate to severe traumatic brain injury (TBI) secondary to physical abuse and in 22 healthy community comparison children. Children with TBI were evaluated an average of 1.6 months after the injury. A toy-centered activity with the examiner was used to capture joint attention and social behavior and an exploratory toy play situation was used to measure independent goal-directed play. The inflicted TBI group showed significant reduction in both social and cognitive domains relative to the comparison group. Canonical correlation analyses disclosed that inflicted TBI was associated with reduction in (a) initiation of social interactions, (b) responsiveness to interactions initiated by the examiner, (c) positive affect, and (d) compliance. The groups performed comparably on indexes of gestural and verbal communication and for the occurrence of negative affect. Joint attention was an area of vulnerability for the TBI group in both social initiation and response contexts. Although general cognitive and motor scores were lower in the inflicted TBI group, the complexity of independent toy play did not differ across groups. Early brain injury causes significant disruption in behaviors regulating initiation and responsiveness in social contexts. Longitudinal follow-up will characterize the long-term consequences of early disruption in joint attention and other behaviors on the development of social and cognitive precursors to executive processes.

Analysis of Variance↗

PubMed2006

The evolutionary basis for the feeding behavior of domestic dogs (Canis familiaris) and cats (Felis catus).

The dentition, sense of taste and meal patterning of domestic dogs and cats can be interpreted in terms of their descent from members of the order Carnivora. The dog is typical of its genus, Canis, in its relatively unspecialized dentition, and a taste system that is rather insensitive to salt. The preference of many dogs for large infrequent meals reflects the competitive feeding behavior of its pack-hunting ancestor, the wolf Canis lupus. However, its long history of domestication, possibly 100,000 years, has resulted in great intraspecific diversity of conformation and behavior, including feeding. Morphologically and physiologically domestic cats are highly specialized carnivores, as indicated by their dentition, nutritional requirements, and sense of taste, which is insensitive to both salt and sugars. Their preference for several small meals each day reflects a daily pattern of multiple kills of small prey items in their ancestor, the solitary territorial predator Felis silvestris. Although in the wild much of their food selection behavior must focus on what to hunt, rather than what to eat, cats do modify their food preferences based on experience. For example, the "monotony effect" reduces the perceived palatability of foods that have recently formed a large proportion of the diet, in favor of foods with contrasting sensory characteristics, thereby tending to compensate for any incipient nutritional deficiencies. Food preferences in kittens during weaning are strongly influenced by those of their mother, but can change considerably during at least the first year of life.

Animals↗

PubMed1992

The dimensionality of Type A behavior within a stressful work simulation.

The present study was conducted to examine the dimensionality of overt Type A behaviors elicited in a simulated stressful work environment. University students played a managerial role while being subjected to time and work-load pressures, and completed the Survey of Work Styles (SWS; Jackson & Gray, 1989). Eighteen behaviors, coded by two raters based on audiovisual recordings, yielded relatively high interrater reliabilities. Principal components analysis revealed four primary factors: Hurriedness, Irritability, Tension of the Lower Extremities, and Restlessness. These factors contribute to an understanding of Type A behavior in that they are the first to be derived from a purely observational approach rather than a combination of observational and self-report methods. Consistent with previous research, differential correlations between the factors and the SWS subscales supported a multi-dimensional interpretation of the Type A behavior pattern. Present findings are compared to those of previous studies of Type A dimensionality.

Adolescent↗

PubMed1999

Strategic aspects of reaction time in world-class sprinters.

Simple reaction time (RT) is defined as the time duration following the initiation of a stimulus and the resultant first observable response. For sprinters, RT to a start should be especially important, as this may determine the outcome of the race. The aim of this study was to investigate whether sprinters (from 100 to 400 m) try to anticipate the starter's shot within the false start limit (100 msec. after the shot). Subjects were male sprinters who have reached the final of a sprint event in World Championships or Olympic Games. Analysis indicated that RT to the starting shot plays a role in the eight finalists' strategy throughout an event (requiring a total of four sprints). Four characteristics of the strategic aspects of RT were found: (i) Increased mean RT from short dashes to longer sprints (from 60 m indoor, to 100 m, 200 m, and 400 m); (ii) RT values increase as a function of race length, i.e., the RT of the first sprinter in a 4 x 100-m relay is no different from that of a 400-m sprinter; conversely, RT of the first relay sprinter in a 4 x 400-m, i.e., a 1600-m race, is significantly different from RT in a 400-m race; (iii) RT decreases from the heats to the final for the eight finalists; (iv) Decreased RT is not observable in less experienced sprinters through the qualifying rounds (junior 18- or 19-yr.-old sprinters, taking part in their own World Championships). RT must be considered a skill dependent upon experience and learning and is associated with race length. The shorter the race, the more important the RT is for the final performance (both time and place), so sprinters try to decrease RT in the shorter dashes (60 m and 100 m). In the longer sprint races (4 x 400-m relay) they are content to respond to the shot. Intermediate distance races elicit intermediate values of RT. Such behavior could be explained by the importance of RT throughout the factors which influence sprint performance and by reference to allocation of concentration resources and expenditure.

Acoustic Stimulation↗

PubMed1996

Cheating in medical school: a survey of second-year students at 31 schools.

BACKGROUND: Although there have been a number of studies of cheating in universities, surprisingly little has appeared recently in the literature regarding academic dishonesty among medical students. METHOD: To assess the prevalence of cheating in medical schools across the country, class officers at 31 of 40 schools contacted distributed a survey in the spring of 1991 to their second-year classmates. The survey consisted of questions about the students' attitudes toward cheating, their observations of cheating among their classmates, and whether they had themselves cheated. The results were analyzed using contingency tables, t-tests, Pearson correlations, and one-way analysis of variance. RESULTS: Of the 3,975 students attending the 31 schools, 2,459 (62%) responded. Thirty-nine percent of the respondents reported witnessing some type of cheating among classmates during the first two years of medical education, while 66.5% reported having heard about such cheating. When reporting about themselves, 31.4% admitted cheating in junior high school, 40.5% in high school, 16.5% in college, and only 4.7% in medical school. Reports of cheating varied across medical schools, but no relationship was found between rates of cheating and medical school characteristics. Men were more likely to report having cheated than were women. The best predictor of whether someone was likely to cheat in medical school was whether they had cheated before, although the data strongly support the role of environmental factors. Medical school honor codes exercised some effect on cheating behavior, but the effect was not large. CONCLUSION: About 5% of the medical students surveyed reported cheating during the first two years of medical school. The students appeared resigned to the fact that cheating is impossible to eliminate, but they lacked any clear consensus about how to proceed when they became aware of cheating by others. The guidance students appear to need concerns not so much their own ethical behaviors as how and when to intervene to address the ethical conduct of their peers.

Adult↗

PubMed1967

Interaction between reflexive fighting and cooperative escape.

Subjects separated by a Plexiglas partition were trained to follow a cooperative escape procedure which produced behavior like the escape responding of individual subjects. Removal of the partition produced fighting and less efficient escape. Efficient escape behavior was restored and fighting disappeared when the partition was replaced. Neither increased space nor a moving toy affected escape behavior. The results indicate that switching animals from an isolated to a social situation produced a change in the effect of shock upon escape which was related to shock-induced fighting.

Animals↗

PubMed1976

Analysis of ribonuclease-nucleotide interactions by quantitative affinity chromatography.

Quantitative affinity chromatography on uridine-5'-(Sepharose-4-aminophenylphosphoryl)-2'(3')-phosphate was developed for the study of binding of ribonuclease species to nucleotide ligands. Elution of the native species ribonuclease-A and -S on the afffinity matrix in 0.4 M ammonium acetate, pH 5.2, containing various amounts of the soluble competing ligand 2'-cytidine monophosphate, reveals an inverse response of elution volume to concentration of soluble ligand. This response conforms to behavior expected for the competing binding equilibria enzyme-soluble ligand and enzyme-insoluble ligand. A-NALYSIS OF ELUTION DATA ALLOWS CALCULATION OF KI and KIM, the dissociation constants, respectively, for the soluble and insoluble protein-ligand complexes. The values of these chromatographically derived constants are similar to values of dissocation constants determined in solution by kinetics of inhibition by 2'-cytidine monophosphate and uridine-5'-(j-aminophenylphosphoryl)-2'(3')-phosphate. Successful competitive elution experiments with [p-F-Phe8]semisynthetic ribonuclease-S' and individual elution trials for [4-F-His12]semisynthetic ribonuclease-S' indicate the utility of the quantitative affinity chromatographic technique for determination of ligand binding properties of ribonuclease derivatives, including inactive species. Nonbiospecific aspects of the interaction of ribonuclease with the affinity matrix in ammonium acetate buffers of concentrations 0.1 M and below were noted, delinating limits of conditions allowing the biospecificity needed for ligand-binding analyses by competitive elution. The dependence of ribonuclease competitive elution behavior on the amount of protein eluted also was examined and related to theoretical considerations in the quantitative application of affinity chromatography.

Binding Sites↗

PubMed2002

Size-dependent life-history traits promote catastrophic collapses of top predators.

Catastrophic population collapses such as observed in many exploited fish populations have been argued to result from depensatory growth mechanisms (i.e., reduced reproductive success at low population densities, also known as Allee effect). Empirical support for depensation from population-level data is, however, hard to obtain and inconclusive. Using a size-structured, individual-based model we show that catastrophic population collapses may nonetheless be an intrinsic property of many communities, because of two general aspects of individual life history: size- and food-dependent individual growth and individual mortality decreasing with body size. Positive density dependence, characteristic for depensatory growth mechanisms and catastrophic behavior, results as a direct and robust consequence of the interplay between these individual life-history traits, which are commonly found in many species.

Animals↗

PubMedDate not supplied

Cardiovascular reactions and impatience in type A and B college students.

The cardiovascular responses of male student volunteers varying in the component behaviors comprising Type A were compared in a choice reaction (RT) task. Since the incidence of coronary heart disease is correlated with Type, the relation of cardiovascular responses to these components is of interest. One component of Type A, impatience, was elicited by a choice RT task with long intertrial intervals. A second component, competitiveness, was elicited by varying monetary reward. Instructions were varied to induce both relatively fast, inaccurate, and relatively slow, accurate RTs. Only persons who were high on the Speed--Impatience component of Type A demonstrated variability in second by second heart rate responses when their RTs were paced at different speeds. Type As (Jenkins Activity Survey and Structured Interview) showed sympathetic-like physiologic changes and performed less well during trials requiring accurate, controlled performance when monetary reward was low. Finally, volunteers high in Competitiveness showed greater trial-to-trial cardiac variability than those who ranked low on this component but were less influenced by reward. Individuals high on the Speed--Impatience and Competitiveness components of Type A may show a brief, intense cardiovascular involvement during performance, but an absence of physiologic involvement between trials. In another study using the same paradigm (1), older, impatient volunteers also had altered heart rate responses, but the exact adjustments differed between age groups. A life span developmental perspective on the psychophysiologic adjustment of Type As is advocated.

Adult↗

PubMed1980

Type A coronary-prone behavior and stress in senior female managers and administrators.

This article describes a study of relationships between Type A coronary-prone behavior patterns, as measured by the Bortner and Rosenman scale, and stress levels, coping ability and psychological stress-related symptoms of a group of 148 senior female managers and administrators. The results indicate that the majority of the sample were categorized as Type A individuals, and that Type A behavior was related to age. A relationship was found between Type A behavior and subjects perceiving themselves as having higher stress levels compared to the female and male peers with whom they worked. Type A individuals perceived that their "ability to cope with stress" was worse compared to that of their female peers and female superiors, but saw themselves as better "copers" compared to their female subordinates. Type A individuals did not see themselves as a source of stress to their subordinates. A relationship was also found between Type A behavior and symptoms of anxiety, frustration and irritation. Results are compared to those of previous relevant research, and the implications of the findings are discussed.

Adult↗

PubMed1999

Protective and damaging effects of mediators of stress. Elaborating and testing the concepts of allostasis and allostatic load.

Stress is a condition of human existence and a factor in the expression of disease. A broader view of stress is that it is not just the dramatic stressful events that exact their toll but rather the many events of daily life that elevate activities of physiological systems to cause some measure of wear and tear. We call this wear and tear "allostatic load," and it reflects not only the impact of life experiences but also of genetic load; individual habits reflecting items such as diet, exercise, and substance abuse; and developmental experiences that set life-long patterns of behavior and physiological reactivity (see McEwen). Hormones associated with stress and allostatic load protect the body in the short run and promote adaptation, but in the long run allostatic load causes changes in the body that lead to disease. This will be illustrated for the immune system and brain. Among the most potent of stressors are those arising from competitive interactions between animals of the same species, leading to the formation of dominance hierarchies. Psychosocial stress of this type not only impairs cognitive function of lower ranking animals, but it can also promote disease (e.g. atherosclerosis) among those vying for the dominant position. Social ordering in human society is also associated with gradients of disease, with an increasing frequency of mortality and morbidity as one descends the scale of socioeconomic status that reflects both income and education. Although the causes of these gradients of health are very complex, they are likely to reflect, with increasing frequency at the lower end of the scale, the cumulative burden of coping with limited resources and negative life events and the allostatic load that this burden places on the physiological systems involved in coping and adaptation.

Adaptation, Physiological↗

PubMed2006

Scent marking in two western Amazonian populations of woolly monkeys (Lagothrix lagotricha).

We describe patterns of scent marking observed in two wild populations of lowland woolly monkeys that were the subjects of long-term studies in the westernmost portion of the Amazon basin. The woolly monkeys engaged primarily in two types of scent marking: chest rubbing and anogenital rubbing. In both study populations, males and females performed both types of scent marking, but males chest-rubbed more commonly than females, while females engaged in more anogenital rubbing. We evaluated two nonexclusive hypotheses for the function of scent marking by woolly monkeys: 1) that scent marking is used in sociosexual contexts, and 2) that scent marking is used to convey information about occupancy of or willingness to defend an area from conspecifics in other social groups. We found no association between the occurrence of scent-marking behavior and location within the home range, but did find that scent marking occurred more commonly than expected on days when copulations, mating solicitations, and intergroup encounters were observed. Additionally, mating activity and chest rubbing were highly correlated across the yearly cycle, even when the potentially confounding variable of ripe fruit availability was controlled for. In woolly monkeys, overt male-male competition is rare and female choice is an important part of the mating system. Our results are most consistent with the idea that scent marking plays a role in advertising male quality or competitive ability, and perhaps in coordinating mating activity.

Animal Communication↗