Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Runaway Behavior”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 415 records · Page 23Linked to original sources
PubMed1994

Mathematical model of temperature-sensitive plasmid replication.

The copy number of a series of plasmids constructed at Odense University is regulated by the lambda PR/PRM promoters and the temperature-sensitive cI857 repressor. At low temperatures, these plasmids exhibit the low copy number of the parent plasmid R1 (5-6 per cell). At high temperatures, the plasmids exhibit runaway replication, reaching copy numbers of greater than 1,000 per cell. A detailed mathematical model of the temperature-sensitive replication of these plasmids has been developed incorporating three features: replication of the parent plasmid, regulation of the lambda PR/PRM promoters by the cI repressor, and thermal denaturation of the cI857 repressor. Models of the first two of these features have been described by others. We revised and extended those models, described the thermal denaturation of the cI857 repressor, and integrated these features to give a comprehensive model of temperature-sensitive plasmid replication. Model predictions were compared to experimental measurements of both steady-state copy numbers as a function of temperature and the change in copy number following temperature shifts up and down. The model accurately describes the qualitative behavior of the system and gives reasonable quantitative results. This is particularly significant since all the parameter values used in this model were determined independently: that is, there was no adjustment of parameter values to match our experimental data. The regulatory system that gives rise to the temperature-sensitive replication of these plasmids is widely used in biotechnology applications, so the elements of the model related to this regulation should be applicable to a wide variety of systems.

Bacterial Outer Membrane Proteins↗
PubMed1995

Continual change in mate preferences.

Secondary sexual characters are highly variable both within and between species. Closely related species often differ markedly in sexual morphology but hardly at all in non-sexual traits. Here we show that Fisher's runaway process of sexual selection is intrinsically unstable and naturally leads to continual change in sexual traits. Runaway leads to semi-stable exaggeration of female preference for a male sexual character, followed by a slow decay of both traits until runaway is triggered again in a different direction. The process then repeats itself resulting in continual change in male sexual traits through time. Allopatric populations are thus expected to diverge without drift or substantial changes in selective pressures. If there is significant mutation bias acting on the male trait, continual change stops and a stable equilibrium appears. Such an outcome is more likely when exaggeration of the male sexual trait signals good genes.

Biological Evolution↗
PubMed2003

Reductions in HIV risk among runaway youth.

Runaway youth are 6-12 times more likely to become infected with HIV than other youth. Using a quasi-experimental design, the efficacy of an HIV prevention program was evaluated over 2 years among 2 groups of runaways: (1) those at 2 shelters who received Street Smart, an intensive HIV intervention program, and (2) youth at 2 control shelters. Street Smart provided youth with access to health care and condoms and delivered a 10-session skill-focused prevention program based on social learning theory to youth. Prior to analysis of the intervention's outcomes, propensity scores were used to identify comparable subgroups of youth in the intervention (n = 101) and control conditions (n = 86). Compared to females in the control condition, females in the intervention condition significantly reduced their unprotected sexual acts at 2 years and alcohol use, marijuana use, and the number of drugs used over 12 months. Male adolescents in the intervention condition showed significant reductions in marijuana use over 6 months compared to control youth. Adolescent HIV prevention programs must proactively identify mechanisms for maintaining behavior change over the long-term, and innovative research designs are needed to allow examination of agency-level interventions.

Adolescent↗
PubMed1987

Genetic factors and the measurement of exploratory activity.

The progenitor strains C57BL/6 and BALB/c and the seven recombinant inbred strains derived from them were used to examine the genetic relationship between two measures of activity and hippocampal lamination defect (Hld). Fifty-three mice (Mus musculus), 9 from each of the progenitor strains and 5 from each recombinant inbred strain, were tested for 16 min in a device which permitted both unobstructed traverse of the length of a runaway and contact with objects which were aligned alongside the runway. The C57BL/6 mice produced significantly more locomotor (runway traversal) activity, whereas the BALB/c showed significantly greater amounts of investigatory (object contact) activity. This reversal of relative position in the distribution of scores was not present for the recombinant strains. There was no dichotomous separation of recombinant strains for either measure. Examination of activity in terms of four consecutive 4-min periods indicates differences among the strains with respect to changes during the test session. The strains may be dichotomized with respect to decrement in activity within the 16-min session, but these groups do not correspond with those reported by others. The inference of a single genetic determinant for activity measured either as locomotor or investigatory responses is not supported by these data, nor is there any apparent relationship between activity and Hld. The critical influence of genetic-environment interactions in determining behavior and the effect of the selection of measurement techniques upon interpretation of data are emphasized by these data.

Animals↗
PubMedDate not supplied

Reaching the hard to reach: innovative housing for homeless youth through strategic partnerships.

This article features three housing programs designed to target the needs of youth aging out of child welfare. One program combines housing and treatment to move substance-dependent youth off the streets; one combines the resources of Urban Peak, the only licensed homeless and runaway youth shelter in Colorado, with the Denver Department of Human Services to prevent youth in child welfare from discharging to the streets; and one addresses the intense mental health needs of this population. It costs Colorado 53,655 dollars to place a young person in youth corrections for one year and 53,527 dollars for residential treatment. It costs Urban Peak 5378 dollars to move a young person off of the streets. This article describes how data have driven program development and discusses how policy implications and relationships with the public and private sector can leverage additional resources.

Adolescent↗
PubMed1998

Runaway ornament diversity caused by Fisherian sexual selection.

Fisher's runaway process of sexual selection is potentially an important force generating character divergence between closely related populations. We investigated the evolution of multiple female preferences by Fisher's runaway process. There are two outcomes of runaway. The first is the evolution of mate preference to a stable equilibrium. This evolution occurs if the benefits of mate choice are sufficiently large relative to the cost of choice. Alternatively, mate preferences evolve cyclically. The rate and pattern of cyclic evolution depends primarily on the individual cost of choice and epistasis in the joint cost of choice. If there are small differences in natural selection (e.g., predation risk) between populations, cyclic evolution quickly leads to divergence in mate preferences and sexual ornaments and so to sexual isolation.

Animals↗
PubMed1992

Ontogeny of chick responses to maternal food calls in the Burmese red junglefowl (Gallus gallus spadiceus).

Burmese red junglefowl (Gallus gallus spadiceus) chicks were reinforced at 5 days old with a mealworm at the end of a runaway in the presence of a maternal food call. Two food calls were used, one made to a highly preferred food item (a mealworm) and one made to a less preferred food item (chick crumbs). Chicks initially approached the food call made to the mealworm faster regardless of reinforcement contingencies, but by the 3rd day of training chicks responded faster to the call that was reinforced. These results indicate that functional experience can modify preexisting response tendencies to food-calling stimuli. We discuss the implications of these results for the interpretation of published accounts that chickens use food calls deceptively.

Aging↗
PubMed2006

The dynamics of Machiavellian intelligence.

The "Machiavellian intelligence" hypothesis (or the "social brain" hypothesis) posits that large brains and distinctive cognitive abilities of humans have evolved via intense social competition in which social competitors developed increasingly sophisticated "Machiavellian" strategies as a means to achieve higher social and reproductive success. Here we build a mathematical model aiming to explore this hypothesis. In the model, genes control brains which invent and learn strategies (memes) which are used by males to gain advantage in competition for mates. We show that the dynamics of intelligence has three distinct phases. During the dormant phase only newly invented memes are present in the population. During the cognitive explosion phase the population's meme count and the learning ability, cerebral capacity (controlling the number of different memes that the brain can learn and use), and Machiavellian fitness of individuals increase in a runaway fashion. During the saturation phase natural selection resulting from the costs of having large brains checks further increases in cognitive abilities. Overall, our results suggest that the mechanisms underlying the "Machiavellian intelligence" hypothesis can indeed result in the evolution of significant cognitive abilities on the time scale of 10 to 20 thousand generations. We show that cerebral capacity evolves faster and to a larger degree than learning ability. Our model suggests that there may be a tendency toward a reduction in cognitive abilities (driven by the costs of having a large brain) as the reproductive advantage of having a large brain decreases and the exposure to memes increases in modern societies.

Biological Evolution↗
PubMed1996

Unilateral amygdala inactivation after training attenuates memory for reduced reward.

This experiment examined the effects of unilateral inactivation of the amygdalae on memory for reduction in reward magnitude. Male Sprague-Dawley rats with bilateral cannulae in the amygdala were trained to run a straight alley for ten 45-mg food pellets. On Day 10, half the animals were shifted to a 1 pellet food reward and half continued to receive 10 pellets. After the shift, the shifted animals displayed a marked increase in response latencies. Immediately following training on Day 10, the animals received bilateral intra-amygdala infusions (0.5 microliter/side) of phosphate buffer or 2% lidocaine in one amygdala simultaneously with infusion of buffer in the other amygdala. On Day 11, the shifted animals given bilateral buffer infusions displayed an increase in response latencies greater than that of the unshifted groups or the shifted groups given lidocaine unilaterally. On Day 12, the runaway latencies of the Shifted Vehicle group remained significantly higher than those of the Unshifted Vehicle group and the Shifted Unilateral Lidocaine-Right group but were not significantly different from those of the Shifted Unilateral Lidocaine-Left group. Also, the latencies of the Shifted Unilateral Lidocaine-Left group were significantly longer than those of the Shifted Unilateral Lidocaine-Right group. These findings indicate that post-shift inactivation of only one amygdala can attenuate the response to reward reduction. These results are consistent with previous evidence that the right amygdala may be more involved than the left in consolidation of memory storage for aversive experience.

Amygdala↗
PubMed2006

Primary alcohol versus primary drug use among adolescents: an examination of differences.

Examination of differences between primary alcohol and drug abusing adolescents can provide valuable direction to intervention efforts, though little research in this area has been conducted. The current study compared primary alcohol and primary drug abusing runaway adolescents who were randomly assigned to family therapy or treatment as usual. Baseline differences, as well as response to treatment, were examined separately for alcohol and drug use and by gender. Although few baseline differences were found, hierarchical linear modeling indicated that alcohol and drug abusing male and female adolescents responded differently to therapy. Primary drug using males showed poorer alcohol use outcomes than did primary alcohol abusers. Specifically, alcohol use increased for primary drug using males receiving family therapy, while drug use decreased in all groups. Findings suggest that alcohol and drug use outcomes might be improved at treatment planning through consideration of client's gender and primary alcohol versus drug use.

Adolescent↗
PubMed1999

TennCare: Tennessee's answer to runaway Medicaid costs.

TennCare was implemented in Tennessee on January 1, 1994, as the state's replacement program for Medicaid. Created through a demonstration waiver under Section 1115(a) of the Social Security Act, TennCare is unlike any other state Medicaid program in the nation because it includes coverage of uninsured and uninsurable Tennesseans. By contracting with managed care organizations (MCOs) to administer the Medicaid benefit package to TennCare enrollees, the state virtually privatized the program and dramatically shifted the state's responsibility from one of total administration to an oversight function only. Amid provider lawsuits, MCO contract controversy, and general chaos surrounding the new program, the implementation of TennCare created one of the most significant health care events in the state's history. This article provides an overview of the TennCare program and its impact on enrollees, providers, and the state budget.

Centers for Medicare and Medicaid Services, U.S.↗
PubMed2002

Ethical considerations for research and treatment with runaway and homeless adolescents.

Ethical considerations for working with runaway and homeless youth in research and treatment settings are presented. Issues of parents' and adolescents' consent for research and treatment are discussed, with particular attention given to the lack of explicit guidelines for working with abused and neglected youth. The principles of beneficence and justice are discussed as they apply to intervening with a high-risk, multiproblem population. The authors offer a rationale for allowing adolescents to self-consent to research and treatment. They argue that in many circumstances, requiring parental consent may not be in the youth's best interest and may preclude his or her participation in treatment and research programs.

Adolescent↗
PubMed1985

Quantitative genetic models of sexual selection.

Quantitative genetic models of sexual selection have disproven some of the central tenets of both the handicap mechanism and the 'sexy son' hypothesis. These results suggest that the 'good genes' approach to sexual selection may generally lead to erroneous results. Runaway sexual selection seems possible under a wide variety of circumstances. Quantitative genetic models have revealed runaway processes for sexually selected attributes expressed in both sexes and for attributes of parental care. Furthermore, the runaway could occur simultaneously in a series of populations that straddle an environmental gradient. While the models support the feasibility of runaway processes, empirical studies are needed to evaluate whether runaways actually happen. Estimates of critical genetic parameters are particularly needed, as well as measures of natural and sexual selection acting on the same population. The models also show that sexual selection has tremendous potential to produce population differentiation, particularly in epigamic traits. Differentiation is promoted by indeterminancy of evolutionary outcome, transient differences among populations during the final slow approach to equilibrium, sampling drift among equilibrium populations, and the tendency of sexual selection to amplify geographic variation arising from spatial differences in natural selection. Recent work with two- and three-locus models of sexual selection has produced results that parallel the results of the polygenic models. Thus the feature of indeterminate equilibria (outcome dependent on initial conditions) is common to both types of model.

Animals↗
PubMed2003

Runaway sexual selection with paternal transmission of the male trait and gene-culture determination of the female preference.

Sexual selection is modeled with a male viability-reducing trait and a female mating preference for that trait both of which are culturally transmitted. Both the male trait and the female preference are transmitted only between same-sex individuals, so that non-random association between the trait and the preference, which would give rise to a Fisherian runaway process, cannot arise. Inclusion of an autosomal gene that confers a female predisposition to acquire a certain preference is shown to allow the coevolution of the male trait and the female preference by a Fisherian process. This holds true even when the female preference has a slight viability cost, provided the male cultural transmission is not perfect. It is also suggested that a Fisherian process can be more easily initiated in these models than in the conventional genetic models. Furthermore, a Fisherian process may cause cultural transmission of female preference to evolve. Additionally, polymorphism can be maintained at the predisposition locus if heterozygous females have a stronger predisposition to acquire the preference than homozygotes. Our models may be applicable to the case when the male trait is a Y-linked genetic or environmentally determined trait.

Animals↗
PubMed1991

Sympathoadrenal effects on extinction of rewarded running in the rat.

Two groups of rats underwent adrenal demedullation or sham surgery before being trained to run in a straight runaway for food reward at a short intertrial interval (90 s). Half of each group of animals were then injected IP with the sympathetic neurotoxin, 6-hydroxydopamine HBr (6-OHDA; 30 mg/kg); the remainder received saline vehicle. After 3 more days of acquisition training, running was extinguished over 12 trials in all rats. Running times were similar in all groups at the start of extinction. In saline-injected animals, extinction proceeded more slowly in the demedullated than in the sham-operated group, but this effect was largely abolished by 6-OHDA. Consistent with previous results, there was evidence that 6-OHDA facilitated extinction, irrespective of adrenal demedullation, but this effect was most apparent in the time taken to emerge from the start-box. The rats were killed two days after the end of the experiment; cardiac noradrenaline levels were depleted by 83% of control values in 6-OHDA-treated animals. The results suggest that the adrenal medulla and sympathetic neurones have opposing and interacting effects on the response to nonreward.

Adrenal Glands↗
PubMed2006

"Everyone dies, so you might as well have fun!" Attitudes of Dutch youths about their health lifestyle.

Most Western societies seem to have embarked on a runaway weight-gain train, equipped with too many accelerators and not enough brakes. Adolescents have been identified as a public health risk group in this area. To uncover youths' attitudes about their health lifestyle, with a focus on overweightness, we conducted a discourse analysis using Q-methodology. Female, Dutch youths between 12 and 15 years rank-ordered statements on issues like eating behaviour, overweightness, health risks, health perceptions and motivations/obstacles for adopting a healthier lifestyle. Q-factor analysis revealed five attitudes: "carefree sporty", "worrying dependent", "contended independent", "looks over content" and "indifferent solitary". The youths were all more or less uninterested in their own health but for different reasons. For most of these youths, neither current nor future health is of major concern, because they feel physically fit, are generally satisfied and happy, or simply do not care. Some are concerned about their eating behaviour due to the consequences it has on appearance, being physically unfit or overweight. Even so, this preoccupation with eating appears far from healthy. Only one of the five health lifestyle attitudes identified combines healthy eating and exercising behaviour. Most youths appear to have little knowledge and many questions regarding health and overweightness.

Adolescent↗
PubMed2002

Initiation of services in the Boston HAPPENS Program: human immunodeficiency virus-positive, homeless, and at-risk youth can access services.

This study evaluates the factors associated with initiation of services in the Boston HAPPENS Program, which is a collaborative network of care consisting of multiservice outreach agencies, community health centers and hospitals, for human immunodeficiency virus (HIV)-positive and hard to reach youth who are 12-24 years old. The program served 2116 youth who were 19.8 +/- 2.9 years old; 64% female; 45% youth of color; 16% gay/lesbian, bisexual, or undecided; and 10% homeless or runaway. At first contact with the program, 56% received outreach services; and 91% received a health intervention. Among those receiving a health intervention, 55% had HIV counseling and testing services, 49% medical care, 24% case management, and 9% mental health services. HIV-positive youth needed more contacts before a first medical visit than those who were HIV-negative or untested (p < 0.001). Different kinds of service sites reached different populations of at-risk youth. Logistic regression modeling showed that for young women, older age, lesbian-bisexual orientation, substance use, high-risk sexual behaviours, and receiving outreach services at first contact were independent predictors of initiation of services at outreach agencies; however, unprotected sex with males, and pregnancy were associated with a greater likelihood of care at hospitals or community health centers. For young men, older age, Asian/other ethnicity, and substance abuse were associated with care at outreach agencies; however, positive HIV status and unprotected sex with females were associated with care at hospitals or community health centers. Comprehensive networks of care offering a continuum of services and a variety of entry routes and types of care sites are needed to connect underserved youth to health care.

Adolescent↗
PubMed2000

Sexual selection and the evolution of costly female preferences: spatial effects.

Models of Fisher's runaway process show that if there is a cost to female preference, no preference or male trait exaggeration will evolve. Surprisingly, this is true no matter how small the cost, which reveals that these models of Fisher's process are structurally unstable (Bulmer 1989). Here a model of Fisher's runaway process is presented to demonstrate that costly female preference evolves very easily when space is explicitly included in the model. The only requirement is that the optimal male phenotype changes across the species' range. The model shows that the spatial average of the female preference and male trait reach an evolutionary equilibrium that is identical to those of nonspatial models, but that the preference and male trait can deviate greatly from these averages at any point in space. For example, if random mating results in the lowest cost to females, then at equilibrium the spatial average preference will be zero. Nevertheless, there will be some locations at which females prefer males with larger ornaments and others where they prefer males with smaller ornaments. Results also show that the structural instability of nonspatial models of Fisher's process is less of a problem in spatial models. In particular, many of the main qualitative features of cost-free spatial models of Fisher's process remain valid even when there are small costs of female preference. Finally, the model shows that abrupt changes in the optimal male phenotype across space can result in an amplification of this pattern when preference has a small cost, but it can also result in a pattern similar to reproductive character displacement. Which of these occurs depends on the magnitude of the cost of female preference. This suggests that some patterns of reproductive character displacement in nature might be explained simply by sexual selection rather than by hybrid dysgenesis and reinforcement.

Animals↗