bluuebunny/crossref_metadata_2025 huggingface dataset:
Acculturation and Health Locus of Control Among Mexican American Adolescents
Authors: Guinn Bobby
Published: March 2007

Health locus of control, a generalized measure of beliefs regarding the source of reinforcement one has over the status of his orher health, was investigated across culture of origin (Mexicanism), mainstream culture (Americanism), and bicultural linguistic acculturation domains among 424 Mexican American adolescents. Study participants were drawn from a predominantly Mexican American population located in the Lower Rio Grande Valley region of Texas. Data were gathered through a self-report instrument consisting of locus of control and acculturation scales. Results indicated that powerful others'external control belief exerted the strongest explanatory power of locus of control in the culture of origin domain, whereas internal control offered the greatest prediction of health reinforcement in both the mainstream and bicultural domains.
Talking about the Composing Process
Authors: TOMLINSON BARBARA
Published: March 2007

We are often suspicious of professional writers' comments about their composing processes because of the aspect of “literary performance.” But we should be equally wary of the accounts of student writers, since they are also unlikely to be veridical. Reasonable, coherent, even captivating accounts are limited by problems of attendance, memory, and reporting, and may be based not on recall but on other cognitive processes. However, despite these problems, retrospective accounts may still prove valuable in studying the writing process.
“Once Upon a Time” Reconsidered
Authors: DYSON ANNE HAAS
Published: March 2007

This article traces the evolution of “Once upon a time” in a child's classroom story writing, drawing upon data collected in a three-year study of writing development in an urban magnet school. The developmental literature on young children's literacy has treated story language as a set of structural routines that children learn from being read to, routines that serve the function of representing imaginary worlds. In contrast, this article assumes that stories are cultural discourse forms that serve multiple functions and that to internalize those forms, children must transform them into tools that are functional within their own social world. Moreover, children's discourse forms and functions are in a dialectical relationships: The initially awkward forms children produce may have limited social meaning—but those forms may elicit social responses that embue them with new functional possibilities and thus lead children to further grappling with forms. In brief, the story forms young children learn from others are not the end products but the catalysts of development.
Narrative Knowers, Expository Knowledge
Authors: DiPARDO ANNE
Published: March 2007

Occasional dissent notwithstanding, “expository” prose—usually conceived as depersonalized and decontextualized—continues to be the main focus of most writing instruction at the secondary and college levels. This article critically examines the opposition of objectified exposition and personal narrative posited by rhetorical tradition and maintained by most composition texts and syllabi today. The liveliness of recent cross-disciplinary discussions regarding the narrative as a uniquely rich mode of thought and discourse contrasts rather sharply with the negative and often impoverished assumptions about storied prose held by most composition theorists and teachers. Unsupported by empirical evidence, such assumptions reflect a cultural bias that prefers abstractions to stories and fails to grasp their dynamic interplay. Where writing instruction is concerned, narrative and exposition are best perceived as poles of a dialectic, with personal experience informing one's interest in abstract knowledge beyond the self, the understanding self becoming enlarged as it “takes in” what is “out there.” The best thinking and writing, it is argued, are at once personal and public, both infused with private meaning and focused upon the world beyond the self.
Accommodating Science
Authors: FAHNESTOCK JEANNE
Published: March 2007

Commentary: When this essay first appeared more than 10 years ago, it built on a small but substantial body of scholarship that declared scientific writing an appropriate field for rhetorical analysis. In the last 10 years, studies of scientific writing for both expert and lay audiences have increased exponentially, drawing on the long-established disciplines of the history and philosophy of science. These newer studies, however, differ widely in approach. Many take the perspective of cultural critique (e.g., the work of Bruno Latour and Stephen Woolgar), whereas others use the tools of discourse analysis (e.g., Greg Myers, M.A.K. Halliday, and J. R. Martin). But, application of rhetorical theory also thrives in the work of John Angus Campbell, Alan Gross, Charles Bazerman, Jean Dietz Moss, Lawrence J. Prelli, Carolyn Miller, and many others. Randy Allen Harris offers a useful introduction to this field in Landmark Essays on Rhetoric in Science (1997).

“Accommodating Science” applies ideas from classical rhetoric and techniques of close reading typical of discourse analysis to the question of what happens when scientific reports travel from expert to lay publications. This change in forum causes a shift in genre from forensic to celebratory and a shift in stasis from fact and cause to evaluation and action. These changes in genre, audience, and purpose inevitably affect the material and manner of re-presentation in predictable ways. Two concerns informed this study 10 years ago: the impact of science reporting on public deliberation and the nature of technical and professional writing courses. These concerns have, if anything, increased (e.g., the campaign on global warming), warranting continued scholarly investigation of the gap between the public's right to know and the public's ability to understand.
Objects of Study in Situated Literacy
Authors: BRACEWELL ROBERT J.
Published: March 2007

This article treats the representations that are studied in situated literacy and an associated methodological approach based on semantic analysis that characterizes the representations in a systematic and principled manner. Application of the method is illustrated for four situated literacy examples: (a) mother-child word-naming games, (b) children's story writing, (c) journalistic writing, and (d) technical writing. The description of representations that is obtained constitutes an explanation of the literacy actions in that it reveals cultural, social, and cognitive influences on these actions.
The Canadian Association for Adult Education
Authors: Kidd J.R.
Published: March 2007

As adult educators in the United States wrestle with the prob lem of establishing a single, nationwide association, it should be helpful for us to review the pattern of national organization and activity that has been developed in Canada. The Associate Direc tor of the Canadian Association for Adult Education has prepared this report at our request.
Information Source and Need Hierarchies of an Adult Population in Five Michigan Counties
Authors: Rieger Jon H. , Anderson Robert C.
Published: March 2007

In a 1965 survey of five counties in the Grand Traverse Bay region, data concerning information sources and needs were ob tained from a 2 per cent sample of households. Adult subjects were asked to identify: 1. topics of importance in their everyday lives about which they had found it "particularly difficult to ob tain useful and reliable information," and 2. sources of informa tion presently being utilized concerning these topics. Results were analyzed in terms of the hierarchial patterns of information needs and information sources by residence, education, age, and sex. The local population was found to rely heavily upon the mass media and various kinds of reading matter for all topic areas and upon institutional sources and officials in certain cases. Young adults relied also upon friends and relatives and exhibited the highest level of need for new information. Adult education pro grams were significant sources in few topic areas and for only selective clienteles. Observations were made about the implica tions of the data for adult educational program development.
Toward a Conceptualization of Leadership for Change
Authors: Robinson Russell D.
Published: March 2007

This paper concerns a conceptualization of leadership for change in adult education, i.e., how change can be effected and who brings it about. The change process, itself, is delineated in terms of research on the subject. Personal influence and opinion leader ship, as these affect the change process, are examined as well as resistance forces, adoption, diffusion, and perpetuation of change. The change leader's helping and leadership roles are detailed. The author advises that this research cannot provide all the answers needed for adult education change leadership. More research re garding communication barriers between social classes, class value difference affecting group participation versus spectatorship, effec tive learning approaches to the lower socio-economic adult, im poverishment barriers to learning, and instruments for measuring these is needed before a definitive, reliable methodology can be provided to leaders of change in adult education.
Reasons for Adult Participation in Group Educational Activities
Authors: Burgess Paul
Published: March 2007

Additional information on why adults participate in educational activities appears to be necessary if the field of adult education is to continue to improve educational offerings. Consequently, this study was designed and conducted to explore further the total framework of educational orientations as developed by Cyril O. Houle, Professor of Education at The University of Chicago.

The results reported here were to test the hypothesis that reasons chosen by men and women for participating in educational activi ties will factor into eight groups. To test the hypothesis, 1,046 adult learners responded to an instrument developed by the author— Reasons for Educational Participation. The results were factor analyzed and seven groups of reasons were identified. Based on the nature of the items comprising each, the factors were named:

The Desire to Know;

The Desire to Reach a Personal Goal;

The Desire to Reach a Social Goal;

The Desire to Reach a Religious Goal;

The Desire to Escape;

The Desire to Take Part in an Activity; and

The Desire to Comply with Formal Requirements.
Participation of the Adult Learner in Program Planning
Authors: McLoughlin David
Published: March 2007

This study investigated the influence of participation in program planning on achievement and attitude. Two experimental groups participated in planning their educational programs. Two control groups completed courses identical to the corresponding experi mental groups, but they did not help plan them. A two hundred item achievement measure and a twelve concept semantic differ ential attitude measure were administered to both groups. The results of a t-test analysis of group mean scores permitted two conclusions. First, adults who participate in program planning appear to have more positive attitudes about their educational experience than those who do not. Second, no evidence was found to support the notion that participation in program planning affects achievement.
Teachers View Students: an Attitude Assessment Through Personality Profiles
Authors: Kitchin William
Published: March 2007

The attitudes of 52 evening college faculty members at three state universities were obtained through their descriptions of an ideal college student and a typical adult evening college student on an adjective check list. Results were reported in terms of per sonality profiles of the two student types, and significant differ ences were found on 19 of the 22 experimental scales used for analysis of the data. These faculty members had a generally less favorable attitude toward adult students than they had toward their ideal conception of a college student. Therefore, the general purposes of the study were achieved. Faculty attitudes could be assessed by means of a personality inventory, which discriminated between relevant concepts, and some expected differences between these concepts were found.
Doctoral Graduates Evaluate the Relevance of Departmental Learning Objectives To Their Professional Responsibilities
Authors: Noel James L. , Parsons Jerry
Published: March 2007

This article reports the results of an evaluation study under taken at NCSU to determine if doctoral graduates of the Depart ment of ACCE who perform different professional roles have different perceptions of the relevance of the Department's educa tional objectives. Relevance as used in the study referred to the utility or usefulness of the Department's objectives to the grad uates' professional responsibilities. The graduates' evaluation was obtained from a questionnaire that contained a list of 38 com petencies that were considered representative of the Department's objectives. Percentage distributions, mean scores, and chi-square values were statistical measures used in analyzing the data. The results indicated that professional responsibility was associated with the graduates' evaluation of the relevance of the Depart ment's objectives. Teachers or researchers gave the research objec tive higher ratings of relevance. Program development specialists and administrators emphasized the relevance of an understanding of adult education as a process of social change and the objectives stressing professional skills needed by the practitioner.
Persisters and Dropouts in the Canada Manpower Training Program
Authors: Truesdell L.R.
Published: March 2007

Manpower training programs help to remove certain labor bottlenecks in the economy by providing individuals with the necessary skills to fill areas of increased labor demand. When clients discontinue training after training places have been made available, the losses to society are noticeable. In particular, it may be noted that during fiscal 1969-70 over 150,000 individuals had enrolled in skill courses under the Canada Manpower Training Program, about 20 percent of whom subsequently discontinued their training. In 1973, about 40,000 individuals who had received funding under the Canada Manpower Training Program dropped out from training.

This paper undertakes an exhaustive treatment of the subject of discontinuation as it relates to the Canada Manpower Training Program and examines the extent and nature of the relationship between discontinuation and various status and input variables by utilizing a dummy-variable multiple regression model. The effects of labor market conditions are also studied. Since the costs in volved in discontinuation are very large, it is important that re search be made available so that the underlying causes may be further explored.

The results indicate that discontinuation in adult training programs is determined by place of residence, the job an indi vidual holds, his attitude towards the course, general economic conditions, and his personal characteristics.
Age Inequality in Educational Opportunity: the Needs of Adult Students in Higher Education
Authors: Parelius Ann P.
Published: March 2007

Several recent policy reports dealing with higher education have focused on adults as students. The expansion of educational opportunities for adults at the college level has been seen as a key element in "overbridging" inequalities between older and younger generations, and in providing a second chance at upward mobility for those unable to complete schooling in their youth. However, the various recommendations put forth to accomplish this expansion reflect a stagnant and narrow view of adult interests and capacities. Emphasizing vocationalism and overlooking the adult's potential for intellectual and personal development, these recommendations would deny adults the stimulation, peer group support, and status socialization they both need and desire.
Differences Between Teaching Adults and Pre-Adults: Some Propositions and Findings
Authors: Beder Harold W. , Darkenwald Gordon G.
Published: March 2007

Do teachers teach adults differently from pre-adults and, if so, what are these differences and what factors determine their magnitude? To examine these questions, data were collected from 173 public school and college teachers who taught both adults and pre-adults. Hypotheses related to overall magnitude of differences in teaching behavior were tested using multiple regression. As predicted, differences in teaching behavior were related to the relative age of the pre-adult comparison group (i.e., greater for school teachers), the extent to which adults were perceived to differ from pre-adults on learning-related characteristics, and the extent to which teachers subscribed to the belief that groups of students with different characteristics should be taught differently. These variables accounted for 41 percent of the variance in the measure of overall difference in teaching behavior. Secondary hypotheses concerning the direction of specific differences in teaching behaviors and perceptions of student characteristics were tested with the t statistic. The results suggest that adults are perceived as more motivated, pragmatic, self-directed, and task-oriented than pre-adults. When teaching adults, as opposed to pre-adults, teachers appear to emphasize responsive, learner-centered behaviors and de-emphasize controlling and structuring be haviors. It was concluded that teachers do in fact teach adults differently from children and adolescents and that these differences can be explained to a significant extent by the variables employed in this study.
Why Psychological Models of Adult Development are Important for the Practice of Adult Education: A Response to Courtenay
Authors: Taylor Kathleen
Published: March 2007

In an article which questions the value of adult development theory to adult educators, Courtenay claims that the literature is ambiguous about the goals of development, misguidedly equates normalcy with growth and development with worthiness, and is unacceptably vague in its descriptions of the characteristics of higher stages of development. This article examines and responds to these objections and maintains that constructive developmental models, in particular, provide an important framework for understanding and supporting adults in the process of growth and change that education often engenders. Furthermore, teaching development theory to developing adults offers them a valuable tool for self-discovery which can enhance and encourage their journey of transition and transformation.
The Influence of Persistence on Literacy Learning in Adult Education
Authors: Fitzgerald Nicholas B. , Young Malcolm B.
Published: March 2007

Limitations in sampling and research design in past studies have hampered understanding of adult education's impact on the acquisition of basic skills. The present study used a selection bias weighting adjustment and ordinary regression techniques in a path analysis approach to identifying variables which directly and indirectly influence reading achievement in adult literacy programs. A major focus of the study was estimating the effect of student persistence (hours of instruction) on literacy outcomes in English as a Second Language (ESL), Adult Basic Education (ABE), and Adult Secondary Education (ASE). Persistence was found to contribute positively to reading achievement only in ESL; negative persistence effects were actually observed for ABE classroom and lab instruction. Considering both direct and indirect effects, the data suggest that adult literacy education can generally be improved by greater investment in full-time staff. It was concluded that an emphasis on student persistence in ABE and ASE instruction may be misguided.
Reconciling Claims for the Individual and the Community: Horace Kallen, Cultural Pluralism, and Persistent Tensions in Adult Education
Authors: Rose Amy D. , O'Neill Linda
Published: March 2007

This article analyzes the work of Horace Kallen and its relationship to his characterization of adult education. After developing philosoplhies supportive of cultural pluralism, individualism, and the American Idea, Kallen integrated his commitments into a sweeping vision of both general and adult education. Kallen wrote on, and was actively involved in, various arenas of adult education throughout his life. Thus, understanding his vision in all its complexity can help us analyze some of the basic tensions inherent in our current and sometimes conflicting conceptualizations of the field.
Major Career Transitions of Youth: The Status Passage from School to Work in Neighborhood Context
Authors: Hubner-Funk Sibylle
Published: March 2007

Recent labor market problems in the Federal Republic of Germany have spurred research on the status passage from school to work. However, those problems are distributed unevenly, varying drastically among the 11 Lander (states), between more and less urbanized regions, and between males and females. Therefore, a thorough understanding of the problems faced by young people as they leave school and try to enter the "dual system" of apprenticeship combined with part-time vocational schooling requires studies that compare the strategies used by males and females in different kinds of communities. The study reported here, "Socialization and Environment," investigated the placement strategies of 140 young people in three neighborhoods: an old downtown neighborhood in Munich; a modern housing area on the outskirts of Munich; and a semirural small town 70 miles from Munich. Semi-structured interviews were conducted with all the young people and with important adults, such as parents, teachers, counsellors, and youth workers. Results confirm the value of an ecological perspective by revealing important interactions between individuals' status characteristics and qualifications (e.g., gender, family background, level of schooling) and the structure and climate of the three neighborhoods, interactions that generated distinctive coping patterns, leading, in turn, to more or less successful placements in the labor market.
An Ethological Perspective on Homosexuality during Adolescence
Authors: Savin-Williams Ritch C.
Published: March 2007

An ethological perspective is presented as an alternative to traditional developmental approaches to adolescence. From an evolutionary point of view, the onset of reproductive capability during adolescence marks the significance of this time during the life course. Thus, the apparent anomaly of male and female youth "preferring" not to engage in heterosexual activities that have the potential to maximize genetic fitness but to participate in homosexual activities that do not have the same adaptive repercussion poses a challenge for an ethological perspective to interpret. To better understand an ethological perspective, basic ethological principles are applied to the emergence and expression of homosexuality during adolescence. First, evidence bearing on the genetic etiological under-pinnings of homosexuality within humans is reviewed through an examination of (a) behavioral genetic studies and (b) hormonal research. Next, adaptive considerations are presented, in particular the prevalence of homosexual behavior among various animal species and human societies, as well as evolutionary pressures that maintain a stable level of homosexuality in the human population. Balanced polymorphism and kin selection are reviewed as answers to the ultimate or functional question. Finally, the "naturalness" of adolescent homosexuality as an outcome of an ethological perspective is proposed. Homosexuality is thus presented as a sexual orientation that is not so much a matter of choice but of biological necessity.
A Naturalistic Study of the Involvement of Children and Adolescents with Their Mothers and Friends
Authors: Montemayor Raymond , Flannery Daniel J.
Published: March 2007

The purpose of the present study was to examine age differences in the involvement of children and adolescents with theirparents andpeers. Thle aspect of involvement examined in this study was engagement, measured by the expressive behaviors of touching, smiling, talking, and gazing. Subjects were members of 307 dyads (n = 122 mother-child dyads and n = 185 peer dyads) that included a child between the ages of 6 and 18 years. Subjects were unobtrusively observed in shopping malls and an amusementpark. Results revealed that expressive behavior in mother-child dyads decreased between childhood and middle adolescence, but increased in male-female dyads. These age differences were especially evident for interpersonal touching. For mother-child dyads, early adolescence was a transitional period during which an engagement style based on talk first emerged. For opposite-sex peers an engagement style dominated by talk in early adolescence shifted to one that also included much touching, smiling, and gazing in middle adolescence.
Conflict Processes and Transitions in Parent and Peer Relationships
Authors: Collins W. Andrew , Laursen Brett , Mortensen Nicole , Luebker Coral , Ferreira Margaret
Published: March 2007

Relational components of three attributes often regarded as individual variables (conflict, autonomy, and self-regulation) were examined in two studies. In Study 1, mothers and their 10-through 12-, 13-through 15-, or 16-through 17-year-old offspring reported expected times of transition to 47 adultlike behaviors (behavioral autonomy) and rated the importance of delaying each transition. Discrepancies from mothers' expectancies were found to be greatest for 13-through 15-year-olds. In Study 2, characteristics and correlates of conflict across different types of relationships were assessed. Sixth-grade and eighth-grade Hispanic American adolescents reported significant differentiation among relationships with mothers, fathers, andfriends infrequency of conflict, conflict resolution strategies and sequelae, and correlates of adolescents'psychosocial competence. Variations suggest that multiple relationships may be involved in the development of autonomy and self-regulation during childhood and adolescence.
The Identity Style Inventory
Authors: White Joseph M. , Wampler Richard S. , Winn Krista I.
Published: March 2007

The Berzonsky (1992b) Identity Style Inventory (ISI) was revised to a sixth-grade reading levelfor use with adolescents and adults with reading limitations. This version of the ISI differs from the original version, which was developed with college students and had a higher than ninth-grade reading level. College students (N = 361) were given both versions of the ISI in a counterbalanced order The revised ISI (ISI-6G) scales (Information, Normative, and Diffuse/Avoidant) were found to be reliable and valid. Construct validity was demonstrated through factor analysis and paired sample t-tests. Correlations between factor scores for each version were high (.79 through .84). Criterion validity was supported by the relations between the ISI-6G scales and predicted alcohol consumption patterns, level of expressed optimism, codependence, and religiosity. Overall, the ISI-6G was comparable to the original ISI and could be used with adolescents and adults.
What Will My Parents Think?
Authors: Wyatt Jennifer M. , Carlo Gustavo
Published: March 2007

Prior researchers confirmed socialization models depicting parenting practices and social cognitions associated with prosocial and antisocial behaviors. However, little research has focused on processes underlying the linkbetween parenting and these behaviors. Per Grusec and Goodnow’s internalization model, children and adolescents develop expectancies regarding their parents’reactions to their behaviors. Adolescents’ expected parental reactions to prosocial behaviors were hypothesized to predict prosocial behaviors; expectations regarding antisocial behaviors were expected to predict antisocial behaviors. For this study, 80 adolescents and their parents reported adolescents’ antisocial and prosocial behaviors. Adolescents completed a measure of prosocial moral reasoning and an assessment of how appropriately they expected each parent to react to prosocial and antisocial behaviors. Expected parental reactions to antisocial behavior predicted lower levels of delinquency and aggression (adolescent report). Expected parental reactions to prosocial behavior predicted higher levels of prosocial behavior (adolescent report) and lower levels of delinquency and aggression (mother report).
Family Relationships, Academic Environments, and Psychosocial Development during the University Experience
Authors: Adams Gerald R. , Ryan Bruce A. , Keating Leo
Published: March 2007

A cohort-sequential study was used to assess family and university environments on identity formation and ego strength. A sample of 294 university students entering school in 1994 and 1995 was assessed in the first and second years. Mailed surveys were completed to assess expressiveness and cohesion in the family, intellectual and supportive activity in academic departments, frequency of critical and analytic teaching in courses, and measures of avoidance decision making, dialectic thinking, identity diffusion and identity achievement, and the ego strength of fidelity. Few developmental changes in any of the variables were observed across the 2 years. However, intellectual and supportive academic departments and democratic family life predicted ego strength. Likewise, the effect of intellectual and supportive academic departments on psychosocial functioning was mediated by information management strategies and the use of dialect thought. The evidence suggests that future research should include both direct effects through perceived environments and indirect effects of the environment through mediating social cognitions.
Parent-Teen Communication about Premarital Sex
Authors: Jaccard James , Dittus Patricia J. , Gordon Vivian V.
Published: March 2007

Twenty-one parental and 16 adolescent topic-specific reservations that parents and adolescents may have about discussing sex and birth control were explored in a sample of 751 African American inner-city youths (14 to 17 years old) and their mothers. Both maternal and adolescent perspectives were obtained with regard to the prevalence of specific reservations and the extent to which they were predictive of communication behavior. Topic-specific reservations were predictive of communication behavior over and above more general family environment variables, such as the quality of the parentteen relationship and the overall quality of communication in general. A number of interaction effects were found, suggesting a differential impact of reservations as a function of the age and gender of the adolescent. The types of reservations expressed by parents were not correspondent with the types of reservations expressed by adolescents.
Dose-Dependent Entrainment of Rat Circadian Rhythms by Daily Injection of Melatonin
Authors: Cassone Vincent M. , Chesworth Michael J. , Armstrong Stuart Maxwell
Published: March 2007

Previous work in our laboratory has shown that daily injection of large doses of the pineal hormone melatonin entrains the free-running locomotor rhythms of rats held in constant darkness and synchronizes the disrupted patterns of rats maintained in constant bright light. The present experiments determined the dose-response characteristics of entrainment to daily melatonin injections and made preliminary biochemical estimates of blood melatonin levels and half-lives after two critical doses of the hormone. The data indicated that the median effective dose for melatonin as an entraining agent in free-running rats was 5.45 ± 1.33 μg/ kg, considerably lower than doses previously employed and lower than doses employed in reproductive and metabolic studies in rats and hamsters. The data further indicated that the response to melatonin was quantal; rats either entrained to melatonin or they did not. No "partial entrainment" was evident, nor were there differences in phase angle, activity, or period among all effective doses. Biochemical estimates of blood melatonin after either 1 mg/kg or 1 μg/kg of melatonin indicated that all effective doses resulted in supraphysiological levels of blood melatonin, although doses of 1 μg/kg resulted in blood levels that were within one order of magnitude of normal nighttime values. Together, the data suggest that the rat circadian system is sensitive to the pineal hormone melatonin at or below doses required to affect rodent reproduction. Whether this sensitivity reflects a role for the pineal gland in rat circadian organization, however, still remains to be determined.
Pineal Melatonin Rhythms in the Lizard Anolis carolinensis: I. Response to Light and Temperature Cycles
Authors: Underwood Herbert , Calaban Michael
Published: March 2007

Both light and temperature can influence the pineal's synthesis of the indoleamine melatonin. An investigation of the effects of light and temperature cycles on the pineal melatonin rhythm (PMR) showed the following: ( 1) Both daily light cycles and daily temperature cycles could entrain the PMR; melatonin levels peaked during the dark phase of a light-dark cycle or the cool phase of a temperature cycle. (2) The PMR could be entrained by a temperature cycle as low as 2°C in amplitude in lizards held in constant light or constant darkness. (3) The length of the photoperiod or thermoperiod affected the phase, amplitude, or duration of the PMR. (4) When presented together, the effects of light and temperature cycles on the PMR depended on the phase relationship between the light and temperature cycles, as well as on the strength of the entraining stimuli, such as the amplitude of the temperature cycle. (5) Exposure to a constant cold temperature (10°C) eliminated the PMR, yet a rhythm could still be expressed under a 24-hr temperature cycle (32°C/10°C), and the rhythm peaked during the 10°C phase of the cycle. (6) A 6-hr dark pulse presented during the day did not elicit a premature rise in melatonin levels. These studies show how environmental stimuli can control the pineal rhythm of melatonin synthesis and secretion. Previous studies have supported a model in which the lizard's pineal acts as a circadian pacemaker within a multioscillator circadian system, and have implicated melatonin as a hormone by which the pineal may communicate with the rest of the system. The lizard pineal, therefore, may act as a photo- and thermoendocrine transducer translating light and temperature information into an internal cue in the form of the PMR. The PMR, in turn, may control the phase and period of circadian clocks located elsewhere, insuring that the right internal events occur at the right time of day.
The Paramecium Circadian Behavioral Rhythm: Light Phase Response Curves and Entrainment
Authors: Hasegawa Kenji , Tanakadate Akihiro
Published: March 2007

The population of a ciliate protozoan, Paramecium multimicronucleatum, exhibits a circadian rhythm as measured by the number of the cells traversing an observation point ("traverse frequency," or TF). The present study examined phase shifting of the TF rhythm by administering 2-hr light pulses at different phases of the circadian cycle to cultures free running in constant darkness (DD). The results were summarized in a phase response curve (PRC), categorized as Type 1. This PRC indicated a relatively narrow phase zone insensitive to the light pulse ("dead zone"). Entrainment of the rhythm to light pulses repeated at 24-hr intervals was also examined, and it was found that the rhythm gradually reached a steady state, following several transient cycles, with the pulses falling at a phase corresponding to the narrow dead zone. Such a steady-state rhythm, with a minimum at ~3 hr after the pulse and a maximum at ~12 hr after the pulse, was mathematically simulated by superimposing a response function to the pulse on a sinusoidal function representative of the free-running rhythm in DD.
Wrist Activity Monitoring in Air Crew Members: A Method for Analyzing Sleep Quality Following Transmeridian and North-South Flights
Authors: Buck Alfred , Tobler Irene , Borbély Alexander A.
Published: March 2007

Home base recordings of motor activity during bedtime, and of subjective sleep parameters, were obtained from air crew members before and after the following routes with multiple flight segments: (1) south-north (SN) across 1 time zone; (2) west-east (WE) across 17 time zones; (3) east-west (EW) across 7 time zones. For the EW route, recordings were also obtained during layover. Only after return from the EW route was bedtime motor activity (measured by a wrist-worn ambulatory monitor) enhanced, was the percentage of bedtime immobility periods reduced, and were frequency and duration of self-assessed waking after sleep onset increased. The subjects rated their sleep as less quiet and felt less rested than during baseline. The various parameters gradually reverted toward baseline during the first 4 days at home. Although sleep showed only minor impairments during the EW route, the subjective jet-lag score was high during layover and after return to home base. Ambulatory activity monitoring is a useful method for assessing sleep quality after long-haul flights.
Simulation of Human Sleep: Ultradian Dynamics of Electroencephalographic Slow-Wave Activity
Authors: Achermann Peter , Borbély Alexander A.
Published: March 2007

The typical declining trend of electroencephalographic (EEG) slow-wave activity (SWA) within a sleep period is represented in the two-process model of sleep regulation by an exponentially decaying process (Process S). The model has been further elaborated to simulate not only the global changes of SWA, but also the dynamics within non-rapid-eye-movement (non-REM) sleep episodes. In this new model, the initial intraepisodic buildup of SWA is determined by the combined action of an exponentially increasing process and a saturation process, whereas its fall at the end of an episode is due to an exponentially decreasing process. The global declining trend of SWA over consecutive episodes results from the monotonic decay of the intraepisodic saturation level. In contrast to Process S in the two-process model, this decay is not represented by an exponential function, but is proportional to the momentary level of SWA. REM sleep episodes are triggered by an external function. The model allows one to simulate the ultradian pattern of SWA for baseline nights as well as changes induced by a prolonged waking period, a daytime nap, a partial slow-wave sleep deprivation, or an antidepressant drug.
Distribution of Circadian Photoreceptors in the Compound Eye of the Cricket Gryllus bimaculatus
Authors: Tomioka Kenji , Okada Yasuo , Chiba Yoshihiko
Published: March 2007

Adult male crickets (Gryllus bimaculatus) show a nocturnal circadian locomotor rhythm, which is driven by the pacemaker in the optic lamina-medulla complex and synchronizes to the light-dark (LD) cycle received by the compound eye. To see whether there was any specially differentiated circadian photoreceptor area in the eye, we examined the effect of a partial reduction of various areas of the compound eye, in addition to a removal of the contralateral optic lamina-medulla-compound eye complex, on entrainability of the locomotor rhythm. All operated animals showed a response to the LD cycle in their locomotor rhythm, no matter which area of the eye was left intact: They either stably entrained to an LD cycle or showed a sign of weak entrainment. The capacity for stable entrainment was still retained when only 262 ommatidia were left. Transient cycles needed for re entrainment, following a 6-hr phase advance of the LD cycle, were measured in 20 reduced-eye animals showing clear stable entrainment. They were in inverse proportion to the number of ommatidia in the reduced eye: The fewer ommatidia there were, the more transient cycles were observed (r = -0.76, p < 0.001). These results suggest that almost the whole area of the compound eye may contain circadian photoreceptors, and that the photic information from each ommatidium may additively affect the circadian clock to entrain via neural integration mechanisms.
Evidence for Independence of Circadian Characters and Extent of Photoresponsiveness in the Djungarian Hamster, Phodopus sungorus
Authors: Kliman Richard M. , Lynch G. Robert
Published: March 2007

Djungarian hamsters ( Phodopus sungorus) exposed to a short-day photoperiod generally respond with a syndrome of physiological and behavioral changes, such as body weight loss and molt to a white pelage. The extent of the short-day-induced responses differs among individuals. Furthermore, some hamsters show no photoresponse. In this study, we sought to determine whether variation in the photoresponse would be associated with circadian function; whether phase angle or free-running period (τ) would differ between responsive and nonresponsive hamsters; and whether changes in these circadian characters would correlate with the extent of weight loss and molt (and the timing of molt onset) in photoresponsive hamsters.

Adult hamsters were kept in a short-day photoperiod (9 hr light, 15 hr dark) for 14 weeks, during which time body weight and molt were measured biweekly. Hamsters were then transferred to cages equipped with running wheels; we measured the phase angle of activity onset under a short-day photoperiod and τ in constant dark. Hamsters exhibiting a short-day-induced molt had a significantly shorter τ and a less negative phase angle than nonmolting animals. Hamsters that exhibited weight loss also had a significantly less negative phase angle, but no difference in τ. No significant Pearson's or Spearman's correlation coefficients were found between extent (or timing) of the photoresponse and the circadian characters in responsive hamsters. Although these results indicate that threshold for photoresponsiveness is related to circadian function, the extent (and timing) of the photoresponse may not be.
Adult Locomotor Rhythmicity as "Hands" of the Maternal Photoperiodic Clock Regulating Larval Diapause in the Blowfly, Calliphora vicina
Authors: Kenny Niall A. P. , Saunders David S.
Published: March 2007

Some basic properties of the adult locomotor activity rhythm and of the maternal induction of larval diapause in Calliphora vicina are described. Diapause responses in Nanda-Hamner experiments indicate that circadian rhythmicity is involved in photoperiodic time measurement (PPTM). However, although the locomotor rhythm shows long-lasting changes in free-running period (aftereffects of photoperiod and constant light) and occasional "splitting," thereby indicating a structural complexity to the circadian system, the overt rhythm may be used as an indicator of phase relationships (or "hands") of the covert system involved in PPTM, within the framework of a simple external-coincidence model for the diapause clock. Thus, in light-dark (LD) cycles close to "resonance" with the circadian pacemaker(s) (T 24, LD 12:12; T 48, LD 12:36; and T 72, LD 12:60), light is restricted to the subjective day and diapause incidence is high. In T 36 (LD 12:24) and T 60 (LD 12:48), light falls into the subjective night and illuminates the postulated light-sensitive phase (Φ1), and diapause incidence is low. Within the primary range of entrainment, light invades the late subjective night in T 20 (LD 12:8), illuminates Φ i, and causes low incidence of diapause; however, it invades the early subjective night in T 30 (LD 12:18) and diapause remains high.
Diurnal, Photoperiodic, and Age-Related Changes in Plasma Growth Hormone Levels in the Golden Hamster
Authors: Laartz Brent , Losee-Olson Sue , Ge Yi-Rong , Turek Fred W.
Published: March 2007

The golden hamster has been used extensively as an animal model for the study of both circadian and seasonal rhythms, and their regulation by the light-dark (LD) cycle. More recently, this species has been used to examine how the generation and entrainment of circadian rhythms are altered in advanced age. Recent studies in both humans and rodents indicate that age-related changes in the diurnal rhythm of pituitary growth hormone (GH) release may mediate some of the adverse effects of aging on a variety of physiological systems. As a first step in determining whether or not age-related changes in circulating GH levels are associated with changes in the regulation and/or expression of circadian rhythms, the effects of age on both the ultradian and diurnal patterns of plasma GH levels were determined in 3- to 22-month-old male hamsters that were bled every 15 min for a 24-hr period while entrained to an LD 14:10 light cycle. An additional study involving a similar blood collection protocol examined whether or not the length of the day is involved in the regulation of plasma GH levels. Although the frequency of pulsatile GH release did not change with advanced age, both the mean levels of GH per sample and the mean amplitude per pulse of GH were significantly elevated in 3- to 4-month-old animals, compared to animals that were 12-13, 15-16, or 21-22 months of age. In hamsters aged 3-4 and 12-13 months, there was an increase in both mean levels and the mean amplitude per pulse of GH, but not pulse frequency, during the night as compared to daytime values. No such diurnal rhythm was detected in the two groups of older animals. A clear diurnal rhythm in GH levels was also detected in animals maintained in a short-day (LD 6:18) cycle, and the mean levels of GH per sample were greater in hamsters maintained on short compared to long (LD 14:10) days. These results indicate that there are pronounced age-related changes in pituitary GH release in the hamster, and that both the time of day and the length of the day influence the pattern of GH release.
Developmental State and the Circadian Clock Interact to Influence the Timing of Eclosion in Drosophila melanogaster
Authors: Qiu Jan , Hardin Paul E.
Published: March 2007

In Drosophila melanogaster, the emergence of adults from their pupal cases (eclosion) is gated by the circadian clock such that it occurs during a window of ∼8-10 h starting 1-2 h before lights-on in 12-h light:12-h dark cycles (LD). This gate is shifted several hours earlier by the clock mutant perS, indicating that the clock controls the phase of eclosion under these conditions. Both the day and the time of eclosion are determined by the interplay between developmental state and the circadian clock. At a certain phase of the circadian cycle, the circadian clock, either directly or through some circadian clock-controlled mechanism, measures developmental state, and those pharate adults that have reached a certain developmental state by this phase eclose during the first available gate, while those that have not wait until a subsequent gate. Using wing pigmentation as a late developmental state marker, an early boundary for when the circadian clock assesses developmental state occurs roughly at the time when lights go out during LD cycles. This event is shifted several hours earlier in perS, showing that it is under circadian control. A fly's developmental state at the time of developmental assessment also influences when eclosion will occur (during the gate) in that flies whose wings have become pigmented early (12-24 h before assessment) will eclose earlier in the gate than those whose wings become pigmented late (0-12 h before assessment). These data suggest that the circadian clock (or some clock-controlled mechanism) measures developmental state (wing pigmentation) in wild-type flies between lights-off and expression of the first clock-regulated marker ∼4-5 h before eclosion and that the developmental state of the fly determines both which gate is chosen for eclosion and when eclosion occurs during that gate.