Pigeons' choices in situations of diminishing returns: fixed- versus progressive-ratio schedules.

In two different discrete-trial procedures, pigeons were faced with choices between fixed-ratio and progressive-ratio schedules. The latter schedules entail diminishing returns, a feature analogous to foraging situations in the wild. In the first condition (no reset), subjects chose between a progressive-ratio schedule that increased in increments of 20 throughout a session and a fixed-ratio schedule that was constant across blocks of sessions. The size of the fixed ratio was varied parametrically through an ascending and then a descending series. In the reset condition, the same fixed-ratio values were used, but each selection (and completion) of the fixed ratio reset the progressive-ratio schedule back to its minimal value. In the no-reset procedure, the pigeons tended to cease selecting the progressive ratio when it equaled or slightly exceeded the fixed-ratio value, whereas in reset, they chose the fixed ratio well in advance of that equality point. These results indicate sensitivity to molar as well as to molecular reinforcement rates, and those molar relationships are similar to predictions based on the marginal value theorem of optimal foraging theory (e.g., Charnov, 1976). However, although previous results with monkeys (Hineline & Sodetz, 1987) appeared to minimize responses per reinforcement, the present results corresponded more closely to predictions based on sums-of-reciprocals of distance from point of choice to each of the next four reinforcers. Results obtained by Hodos and Trumbule (1967) with chimpanzees in a similar procedure were intermediate between these two relationships. Variability of choices, as well as median choice points, differed between the reset and no-reset conditions.(ABSTRACT TRUNCATED AT 250 WORDS)     

Optimizing Expression of the Common Human Genome for Child Development

Molecular biology has moved the gene-environment issue in behavior genetics to how and when expression of the human genome is triggered and maintained. How does environment influence gene expression? How many genes are expressed in producing a given behavior? The genome is a data bank and does not automatically create a working brain. The body and brain grow well when (a) endocrine hormones initiate and promote the expression of genes, (b) nutrition is sufficient to sustain the production of proteins, and (c) stress does not suppress gene expression. The growth of brain synapses also requires appropriate neural stimulation. To study gene expression, it is essential to view the complex biology of the cell from a system context that includes the entire genome plus the biological and psychological environments. Optimizing geneexpression for child growth can be achieved by a balance of medicine, nutrition, and appropriate physical, educational, and psychological environments.     

Breast cancer risk analysis: A genetic epidemiology service for families

Breast Cancer Risk Analysis, a service for women with breast cancer and their families, makes use of information drawn from fields such as genetics, epidemiology, and counseling. Its aim is to provide individuals with background information and information regarding the etiology and risks of breast cancer. Based on this information, individuals are helped to make appropriate decisions pertaining to treatment and follow-up. While making use of some of the information and processes used in genetic counseling, Breast Cancer Risk Analysis differs from most types of genetic counseling for reproductive decisions. Some of these differences are discussed here.     

Continuing education in genetics for Adoption workers in Wisconsin

In response to 1982 legislation and 1984 changes in the Wisconsin Adoption Records Laws requiring the collection of a medical-genetic history at the time of termination of parental rights, a continuing education program in genetics was conducted for adoption workers in 1984 and 1985. The education program provided 14 workshops in five locations throughout the state and consisted of a variety of formats and levels of training. In all, 164 participants were trained at least at the introductory level with approximately 40 of these individuals taking part in the advanced levels of training. Evaluations of the training by participants and by a sample of the agency supervisors of trainees ranked the program very highly. A review of genetic history forms completed in post-training sessions verified the expectation that training was beneficial. Trained workers completing the medical-genetic history forms scored somewhat higher than untrained workers and much higher than parents who completed the forms without professional guidance. Medical-genetic history forms completed by birth fathers as part of step-parent adoptions contained little to no useful information about the birth father's genetic background.     

Is personality disorder inherited? An overview of the evidence

Genetic factors appear to be of considerable importance in determining normal variation in personality. This is suggested by family, twin, and adoption studies as well as by indirect findings based on animal and psychophysiological studies. In contrast, there is consistent evidence that the contribution of shared family environment is minimal. Despite difficulties in defining personality disorder, it appears that many types of personality disorder, in particular schizotypal personality disorder and antisocial personality disorder/criminality, are also influenced genetically. The genetic transmission of normal personality traits and disorder is most easily explained by the contribution of multiple genes of small effect rather than by single-gene inheritance. Recent advances in molecular genetics have led to the localization of genes of minor effect for some traits. This raises the possibility of detecting a molecular basis of traits and disorders such as personality and personality disorder.Anita Thapar is supported by a Research Training Fellowship from the Medical Research Council.     

ADEQUACY OR ORTHODOXY? CHOOSING SIDES AT THE FRONTIER

Abstract. Arthur Peacocke's seminal contribution to the dialogue between science and theology is considered along three dimensions: epistemology, anthropology, and the concept of God. It is suggested that his view of a "hierarchy of disciplines" (1) may not completely characterize the way theology interacts with science, and (2) could limit the creative friction between them. His emphasis on humans as "more than" DNA could result in an anthropology that fails to exploit insights that biology could shed on theological puzzles as the impact of genetics is more widely appreciated. His concept of God may also need to be modified more radically to express our understanding of nature in an age of genetics.     

蛋白质化学与分子生物学携手前进

蛋白质化学的发展历经了几次重大的转变,分析仪器的商品化使蛋白质从实验室走向市场;一级结构信息促进了多肽的合成与改造;分子生物学技术的成熟使人们从设计改造功能蛋白转向设计基因,并尝试进行基因治疗和ＤＮＡ免疫。这些转变,使蛋白质化学技术与分子生物学技术成为人们手中的工具,为人们研究生命拓宽了思路。     

Genetic and environmental influences on the association between performance‐based self‐esteem and exhaustion: A study of the self‐worth notion of burnout

In the self‐worth model, burnout is considered to be a syndrome of performance‐based self‐esteem (PBSE) and experiences of exhaustion. Studies have shown that PBSE and burnout indices such as Pines’ Burnout Measure (BM) are associated. Whether these variables have overlapping etiologies has however not been studied before. Genetic and environmental components of covariation between PBSE and exhaustion measured with Pines’ BM were examined in a bivariate Cholesky model using data from 14,875 monozygotic and dizygotic Swedish twins. Fifty‐two per cent of the phenotypic correlation (r = 0.41) between PBSE and Pines’ BM was explained by genetics and 48% by environmental factors. The findings of the present study strengthen the assumption that PBSE should be considered in the burnout process as proposed by the self‐worth conception of burnout. The present results extend our understanding of the link between this contingent self‐esteem construct and exhaustion and provide additional information about the underlying mechanisms in terms of genetics and environment. This finding corroborates the assumed syndrome view on burnout, while it also suggests an altered view of how the syndrome emerges and how it can be alleviated.