bluuebunny/crossref_metadata_2025 huggingface dataset:
A Historical Analysis of an Adult Education Institution
Authors: Beck Kenneth N.
Published: March 2007

This study is a historical analysis of an adult education institu tion, the American Institute of Sacred Literature. An attempt is made to determine those factors which led to the establishment, growth, development, decline and death of the Institute. The writer also examines the nature and extent of the Institute's at tachment to other agencies (i.e., through finances, personnel, clien tele, programs, and facilities) and traces changes within the Institute's administration which may have stifled or encouraged growth. A series of questions provide a guiding framework for data collection using much primary source material along with interviews. Examination of the data revealed that the Institute evolved in five phases: Establishment and Innovation, Reorganiza tion and Adaptation, University Inclusion and Stability, Inflexi bility and Decline, and Retrenchment and Dissolution. Information is provided on one of the earliest correspondence schools in the United States, the career of William Rainey Harper, and the early history of The University of Chicago.
Some Perspectives On the Phenomenon of Participation
Authors: Douglah Mohammad
Published: March 2007

This article explores the concept of participation from a number of perspectives and suggests some implications of these perspec tives for adult educators. The author suggests that in spite of the variety of definitions of participation, certain general properties of the concept can be delineated. These include the dimensions of individual-group, quantity, quality, and means-end. In reviewing selected research and theory on participation, special emphasis is given to two areas: 1. models of the motivational bases of participation, and 2. research which investigates the results of participation in decision-making. The author concludes by raising a number of questions about participation which have special significance for adult educators.
Alienation Among Rural Adults of Low Educational Attainment
Authors: Dickinson Gary
Published: March 2007

To identify those socio-economic characteristics of rural adults differentiating among those of varying levels of alienation, struc tured interviews were conducted with a sample of household heads resident in a specified area of British Columbia. Educational attainment was found to be inversely related to alienation in the total sample. Data from 293 respondents with eight or less years of school completed were analyzed with respect to alienation category, and five variables which were statistically significant at the .05 level. In the educationally disadvantaged group, the less as compared to the more alienated household heads were charac terized by a birthplace closer to the present place of residence, more participation in community organizations, a farm rather than non-farm occupation, less unemployment in the preceding three years, and greater satisfaction with the present job.
German Adult Education Following the Unification of 1871
Authors: Pirtle Wayne G.
Published: March 2007

German unification in 1871 was followed by an intense inter est in adult education as a tool for forging the disparate German states into one nation. Representative of the institutions for adult education established during the 1870s were "The Society for the Diffusion of Adult Education" and "The Humboldt Academy." Their programs consisted largely of "science" lectures and small lending libraries dispersed throughout Germany. In their attempts to remain neutral on all contemporary issues, they lost, however, their ability to attract many social groups including the working class. After the promulgation of the Anti-Socialist Law of 1878 most adult education designed expressly for the working class was suppressed. The working class countered by rejecting upper and middle class values and education as alien to it. During the 1890s there emerged a strong emphasis by many adult educators on art and aesthetic programs for the general public. At the same time other adult educators believed that an indiscriminant exposure to "culture" was not necessarily educational. Supporting this view, one influential educator in Berlin, Robert von Erdberg, advocated an intensive, individualized education for the potential leaders among the working class as well as other social classes. This, he believed, would be more effective in formulating social values that could weld together the mutually divisive elements in German society. This view was eventually to revolutionize adult education in Germany.
Correctional Education and Recidivism in a Woman's Correctional Center
Authors: Johnson David C. , Shearon Ronald W. , Britton George M.
Published: March 2007

This study was designed to determine whether academic edu cational achievements of women inmates during incarceration had significant effects upon their subsequent recidivism. An experi mental group of 100 ex-inmates who had received the General Educational Development (G.E.D.) certificate while in prison was equated in terms of 14 personal and criminal factors to a control group of 100 ex-inmates who had not completed the G.E.D. pro gram. The groups were then compared in terms of recidivism rates. Although the proportion of non-recidivists was slightly higher for the G.E.D. group than for the control group, the difference was not significant at the .05 level of confidence. Thus, the hypotheses that successful participation in academic educational programs by women inmates reduces their subsequent recidivism was not sup ported.
Adult Civic Education in the Post-World War Ii Period
Authors: Stubblefield Harold W.
Published: March 2007

Adult civic education assists adults to acquire the compe tencies necessary for participation in civic life. After World War II, adult civic education sought to promote citizen participation, individual development, and the creation of an aware and informed citizenry. These efforts were accomplished through liberal educa tion, public affairs education, political education, human relations, leadership, and participation training, and community develop ment. Both the community development study and action approach and forms of group learning were used extensively in developing adult citizens. The ultimate purpose of adult civic education was to create a public opinion able to assess critically the accomplish ment of government and citizens able to identify and solve com mon social problems.
A Model for Studying Determinants of Intention To Participate in Continuing Professional Education
Authors: Grotelueschen Arden D. , Caulley Darrel N.
Published: March 2007

This article presents a theoretical model for a program of research into the determinants of a professional's intention to par ticipate in continuing education. This model is based on Fishbein's (4) general theoretical framework. The adapted framework con sists of three components. The first component is the professional's attitude toward participating in continuing education. This atti tude is taken to be dependent on what the professional believes will be the consequences of participating and what value the pro fessional places on these consequences. The second component is related to the professional's perception of what most people who are important to the professional think about his or her participa tion. It is also related to the importance the professional places on these perceived expectations. The third component is related to the professional's personal beliefs about whether he or she should participate and to the professional's motivation to comply with these personal beliefs. For each component, items are pre sented which illustrate how the component might be assessed.
An Environmental Interaction Model for Agency Development in Adult Education
Authors: Beder Harold W.
Published: March 2007

This article presents an environmental interaction model for agency development in adult education. Agency development is defined in terms of quantitative growth. Development is conceptualized as being contingent on the agency's ability to garner scarce and valued resources from the environ ment through strategically planned inter-organizational linkages. A pro gram development dynamic operates in that each success at garnering such resources as learners, money, staff, power and domain improves the agency's bargaining position for securing more resources. The article con cludes with a discussion of how inter-organizational linkage is affected by such variables as technology, domain, system openness, bureaucratization, organizational goals and environmental stability. Arguments for the ap propriateness of the model for adult education are presented, as well as im plications for future research.
Audio Cassettes as a Means of Professional Continuing Education for Pharmacists
Authors: De Muth James E.
Published: March 2007

This paper examines the use of audio cassettes as a means of continuing profes sional education. Along with a review of the various educational uses for audio cassettes and the presentation of one successful model for continuing education, the paper reports on the results of a study of over 700 pharmacists utilizing ten dif ferent cassette courses. The study revealed that these courses were valuable and practical learning experiences, equally acceptable to all pharmacists regardless of practice setting or experience. They offered a convenient and time-saving method for professional study and most pharmacists would recommend them to their col leagues. A majority of the pharmacists studied had participated previously in this form of continuing education, and almost all intended to enroll in additional courses in the future. Although the study was restricted to pharmacists, the find ings and the utilization of audio cassettes could be appropriate for other profes sions.
Motivations and Characteristics of Adult Students: Factor Stability and Construct Validity of Tie Educational Participation Scale
Authors: Fujita-Starck Pamela J.
Published: March 2007

Effective and responsive adult education programming requires a clear understanding of the characteristics, needs, and aspirations of program participants. This study investigated the factor stability and construct validity of Boshier's Educational Participation Scale (EPS), as part of a series of studies designed to better understand a diverse adult student body participating in a broad program of continuing education. Responses from 1,142 students in programs at a large state university were utilized in the analysis. The results confirmed Boshier's seven factor typology. Reliability of the EPS scales was found to be acceptable. Construct validity of the EPS was investigated by predicting membership in three curricular groups. The findings revealed a distinctive set of student characteristics and reasons for participation between the defined curricular groups.
Beyond the Myth of Self-Actualization: Reinventing the Community Perspective of Adult Education
Authors: Jansen Theo , Wildemeersch Danny
Published: March 2007

In this contribution, we discuss two tendencies in mainstream adult and continuing education. First, there is the tendency to gear adult and continuing education towards individualized responses to present day processes of social transformation. We interpret these changes with reference to the concept of the risk society. Second, we comment on the tendency of adult and continuing eduction to increasingly frame these individualized responses in labor market terms. These tendencies provoke a privatization of identity development and may even contribute to new forms of social inequality. In contrast with these developments, we emphasize the importance of adult education for social participation and social responsibility. In this perspective we reconceptualize both the ethic and the aesthetic dimension of adult education.
Changing Psychopathology in Female Adolescent Inpatients: 1973 versus 1983
Authors: Grob Mollie C. , Eisen Susan V.
Published: March 2007

This study raises the question of whether sociodemographic factors or manifestations of psychopathology among hospitalized female adolescents (ages 15-19) changed from 1973 to 1983. Two samples of 50 patients each were selected from among psychiatric hospital admissions in 1973 and 1983. Demographic data, psychiatric histories of both patient and family, information about the family constellation and patients' clinical profiles at admission were obtained from patients' hospital records. Differences between the cohorts suggest that symptoms and problems have changed somewhat in the 10-year period and that the more recently admitted patients show evidence of more serious illness. Implications as to the focus of future treatment programs are discussed.
Adolescent Male Sexuality and Heterosexual Masculinity: A Conceptual Model and Review
Authors: Marsiglio William
Published: March 2007

The theoretical and empirical literature on adolescent sexuality has focused disproportionately on females. Given this bias, and the current public concern over the spread of sexually transmitted diseases (STDs) and Acquired Immune Deficiency Syndrome (AIDS) among the adoles cent population, a systematic interpretation of adolescent male sexuality is warranted. Adolescent male sexuality is discussed here within the context of an integrated conceptual framework that incorporates major themes from the scripting perspective, subjective expected utility theory, and the notion that initial sexual encounters are negotiated episodes in an interpersonal scripting context. The relevant themes and concepts are synthesized by demonstrating how the imperatives associated with the traditional image of masculinity intersect with features of adolescence to affect the various levels of the scripting process and adolescent males' perception of and orientation toward their sexual expression. Because the scripting process for adolescent male sexuality is a function of the larger sociohistorical context, the potential impact of several current and future developments, including the growing emphasis on condom use, is dis cussed also.
Explanations of Sexual Assault among Violent Delinquents
Authors: Fagan Jeffrey , Wexler Sandra
Published: March 2007

Despite recent attention both to sex offenders and violent delinquents, there is little empirical knowledge on the causes and correlates of juve nile sex offenses. Juvenile sex offenders (N = 34) were identified among a sample of chronic violent offenders (N = 242) from official records and face-to-face interviews. Juvenile sex offenders were 14. 1 percent of the sample. Sex offenders more often lived with their birth parents while violent offenders often lived in single parent families. Sex offenders had fewer nonviolent offenses, but more often had been incarcerated. Sex offenders had lower self-reported delinquency, fewer drug and alcohol problems, and less often were gang members. Their families, their sib lings and friends had less justice system involvement. However, sex offenders more often came from families with spousal violence, child abuse, and child sexual molestation, according to both official and self reports. They appear to be more sexually and socially isolated, less often have girlfriends or report sexual activity, interest or experience. They had stronger beliefs in the law, but fewer internal behavioral controls. Juve nile sex offenders appear to be a "hidden" population, more closely resembling normative populations than delinquent populations on a vari ety of social factors and attitudinal variables. Further research is needed on broader populations of sex offenders to expand and validate these preliminary findings.
Ego Development and Perceptions of Parent Behavior in Adolescent Girls
Authors: Lasser Victoria , Snarey John
Published: March 2007

The developmental dynamics of achieving egoautonomy in adolescent girls have not been adequately explored. This is a report of a qualitative study that investigated the relationship between female adolescent ego development and parent behavior from the perspective of the adolescent girl's view of her parents. The thesis of the study was that in order to understand the process of ego development in the adolescent girl, it would be necessary to understand that her development is embedded within the context of a father-daughter-mother triangle. Twelve high school senior girls were randomly selected from a larger study and intensively interviewed as they were negotiating the transition from high school to college. Findings indicated that perceived parenting behaviors of their mothers andfathers and the girls' level of ego development were related lo each other and to variations in the effectiveness with which the adolescents negotiated the difficulties associated with the transition to college.
A Functional Comparison of Same-Sex and Opposite-Sex Friendships during Adolescence
Authors: Lempers Jacques D. , Clark-Lempers Dania S.
Published: March 2007

The present study investigated how adolescents perceive their same-sex and opposite-sex friendships. A total of 576 6th-through 12th-grade students rated both their same-sex and opposite-sex friendships on 11 functional and structural attributes. MANOVA and ANOVA results revealed significant gender differences for most of the attributes, but no grade differences. The females gave higher ratings than did the males to both the same-sex and opposite-sex friendships. Whereas the same-sexfriendship received higher ratings than the opposite-sexfriendship on some attributes, the overallpattern offindings in this regard indicated that same-sex and opposite-sex friendships share in functional importance by simultaneously providing for many of the social needs of adolescents.
Family Differentiation, Peer Differentiation, and Adolescent Adjustment in a Clinical Sample
Authors: Gavazzi Stephen M. , Anderson Stephen A. , Sabatelli Ronald M.
Published: March 2007

This is a study of the relationships among family system dynamics, peer network characteristics and adolescent personal adjustment. Specific characteristics of both the family system and the peer network are thought to have a significant impact on the adolescent's ability to master certain developmental tasks and therefore contribute to the adolescent's ongoing growth and development. Apart from the separate influences of these factors, the study attempts to explore the combined influence offamily system and peer network characteristics through the use of interaction terms. Results indicate that adolescents 'psychosocial maturity levels are significantly predicted by both family support and peer conformity pressure, as well as the interaction term of Family Support x Peer Support. The results also indicate that severity levels of adolescents 'problematic behaviors are significantly predicted by family support and parental intrusiveness, as well as the interaction term of Parental Intrusiveness x Peer Support.
Figure Preference, Body Dissatisfaction, and Body Distortion in Adolescence
Authors: Phelps LeAdelle , Johnston Lisa Swift , Jimenez Dayana P. , Wilczenski Felicia L. , Andrea Ronald K. , Healy Robert W.
Published: March 2007

The present study was designed to evaluate gender and age effects on three multidimensional factors (i.e., figure preference, body dissatisfaction, and body distortion) that potentiate eating-related problems among adolescents. Data from 454 students (X age 15.03) found females preferred afigure significantly thinner than their current status, whereas males were generally pleased with their body proportions. This discrepancy resulted in significant gender differences in idealfigure preference and body dissatisfaction. School level (high school vs. middle school) by gender, two-way ANOVA comparisons found an interactional effect, with high schoolfemales evidencing significantly higher levels of body dissatisfaction and distortion than the middle schoolfemales and males. Further analysis with females found body dissatisfaction increased with age in a linear configuration, whereas body distortion followed a curvilinear pattern.
Adolescent Coping Styles and Perceptions of Parental Child Rearing
Authors: Dusek Jerome B. , Danko Maribeth
Published: March 2007

To relate adolescent coping styles to parental rearing practices, 107 15-and 17-year-olds were classified into one of four groups (authoritative, authoritarian, indulgent, or neglectful) based on perceptions of theirparents' rearing practices. Subjects completed the Adolescent Coping Orientation for Problem Experiences, a measure of adolescents' general coping styles. Those in the indulgent and authoritative groups used more problem-focused coping; those in the indulgent and neglectful groups used more cognitive coping. Perceiving the parents as more warm and supportive was related to greater problem-focused coping; perceiving the parents as higher in firmness and monitoring was related to lowered emotion-focused and cognitive coping. The results are discussed in the context of rearing practices impacting on coping preferences (a) through their influence on encouraging the use of parents and others as sources of instrumental and emotional social support and (b) by facilitating better psychological and psychosocial adjustment.
Studying Youth Programs to Assess Influences on Youth Development
Authors: Oden Sherri
Published: March 2007

To support and foster youth development, there is a need to study youth programs and activities-in schools, communities, and youth organizations. To expand knowledge of programs and to determine influences on youth development, research should include a diversity of analyses on the current knowledge base, current program status factors, program and participantprocesses, program outcomes, and policy orprogram development. Methodology from current educational, developmental, and other social science research provides illustrations of effective approaches and roles for researchers that could be applied to studying youth programs in short-term and longitudinal studies. Learning more about programs willprovide a more completefoundationfor the emerging field of youth development.
Sexual Behaviors and Attitudes of High School Students in the Kingdom of Swaziland
Authors: McLean Polly E.
Published: March 2007

This study examined sexual behaviors and attitudes of high school students, with a steady partner, in the Kingdom of Swaziland, southern Africa. Questions asked were: What proportion of adolescents with a steady partner is coitally active and with what frequency? How do adolescents feel about multiple partners? What are adolescents' contraceptive practices? What gender differences emerge regarding demands and expectations of coitally active adolescents? Multiple methods of data collection were employed. The results showed that most respondents had become coitally active by the time they were 16 years of age. Genderdifferences emerged regarding (a) attitudes about multiple partners and (b) demonstrating affection. Growing consumerism is beginning to have some effect on adolescent sexuality. There is no school policy on teachingfamily life education. Pregnancy is a problem as well as are septic abortions. Parental guidance is less influential than in the past, yet traditional values attached to gender roles are still intact among the adolescents interviewedfor this study.
Developmental Changes in Questioning Strategies during Adolescence
Authors: Drumm Patrick , Jackson Dorothy W.
Published: March 2007

Males andfemales from early, middle, and late adolescent age groups were tested with three arrays in a modified version of a 20 Questions problem-solving task The arrays differed by perceptual and conceptual categorical contrasts. The participants'questions were examined to determine (a) how efficiently they used the categorical information present in the arrays and (b) the frequencies of different question types. Analysis showed that the arrays varied in how efficiently they were solved and that late adolescents were the most efficient at reducing alternatives by their third question. Question types differed predictably by array, exceptfor a slight bias favoring conceptual category questions for an array with a balanced mixture ofperceptual and conceptual properties. Developmental differences in both efficiency and question type seem related, and middle adolescent males exhibited a high frequency of syncretic questions, which may constitute aform of risk taking.
Adolescent Friendship Pairs
Authors: Akers James F. , Jones Randall M. , Coyl Diana D.
Published: March 2007

A total of 1,159 high school students (Grades 10 through 12) responded to a questionnaire designed to assess best friends' similarities in identity status (EOM-EIS) and related behaviors, attitudes, and intentions. Mutually identified best friends, nonmutually identified bestfriends, and randomly paired nonfriends (each n = 198 pairs) were identified to test hypotheses concerning friendship similarities. Tests of similarity indicated that mutually indentified best.friends shared distinct similarities in ego identity. Similarity indicators were greater for measures ot 'ego identity in specific content areas than for the global identity status levels or the interpersonal and ideological domains. In addition, mutually identified best friends were more similar than were nonffriends on many behaviors, attitudes, and intentions that were expected to be related to ego identity. Results replicate those of'existing investigations of friendship attitude and behavioral characteristics and extend friendship similarities into psychosocial contexts.
Filipino Adolescents’ Parental Socialization for Academic Achievement in the United States
Authors: Salazar Lilia P. , Schludermann Shirin M. , Schludermann Eduard H. , Huynh Cam-Loi
Published: March 2007

Different parental socialization practices tend to predict the academic achievement of European- and Asian-American adolescents. This study explored the processes whereby parental socialization practices lead to Filipino adolescents’ academic achievement. A sample of Filipino students from San Francisco (N = 535) of both genders (ages 11-19) completed questionnaire measures of a proposed structural equation model with the causal sequence: authoritative academic socialization, importance of family reputation, attribution of success, student involvement in studies and grade-point average (GPA). Structural equation analyses supported the hypothesized model with GPA as the dependent variable: Family reputation and internal attribution were found to mediate the relation between authoritative parenting and GPA.
Engagement Models for Adolescents in DATOS-A
Authors: Broome Kirk M. , Joe George W. , Simpson D. Dwayne
Published: March 2007

Based on the importance of during-treatment activities for improving outcomes, relationships between patient background, treatment readiness, and therapeutic engagement were examined in a national sample of adolescents admitted to 20 treatment programs representing three modalities. Patients with higher readiness for treatment at intake subsequently became more therapeutically involved, replicating previous findings on relationships between motivation and engagement in adult samples. One of the most influential background factors associated with higher treatment readiness was patient relationships with family and friends. Interventions that focus on treatment readiness appear to be appropriate strategies for improving treatment engagement.
Reliability and Validity of an Interview Assessment of Attachment Representations in a Clinical Sample of Adolescents
Authors: Scharfe Elaine
Published: March 2007

Although several researchers have discussed difficulties when assessing attachment representations in clinical samples, fewhave formally assessed reliability and validity of attachment in clinical samples. In this study, reliability and validity of attachment in a clinical sample of adolescents was assessed. Adolescents (50 females and 77 males; average age 13. 6 years) completed questionnaires to assess interpersonal anxiety and avoidance and were administered the Family Attachment Interview and the Wechsler Intelligence Scales for Children–III. Interviewcodings of attachment representations were reliable; however, findings highlighted possible limitations of categorical assignments. Consistent with previous research, attachment representations were not associated with cognitive abilities and were associated with latent variables of avoidance and anxiety. Discussion of results focuses on the benefit of using continuous ratings of attachment; the usefulness of attachment theory when counseling distressed youth; and the theoretical importance of understanding attachment representations during adolescence.
Adaptive Behavior in Adopted Children
Authors: Grotevant Harold D. , Ross Nicole M. , Marchel Mary Ann , Mcroy Ruth G.
Published: March 2007

This study examines potential links between early risk and problematic developmental outcomes in a sample of adopted children during middle childhood (mean age = 7. 8 years). No direct relation was found between prenatal, perinatal, or preplacement risk factors and problematic socioemotional adjustment. When 12 high-risk children and their families were studied more intensively, collaboration in relationships within the adoptive kinship network did account for variations in socioemotional outcomes for these children. Collaboration in relationships refers to proactive cooperation among the child’s adoptive and birth family members on behalf of the child’s best interests. The usefulness of this concept for studying other types of complex family forms is suggested.
Cross-Generation Perceptions of Academic Competence
Authors: Bornholt L. J. , Goodnow J. J.
Published: March 2007

This study examined the role of parents acting as a social influence on adolescents’self-knowledge about competence at academic activities. The participants were adolescent boys and girls (N = 115) between the ages of 11 to 16 and their mothers and fathers. A proposed model of parental perceptions as mediating influences of past performances on adolescents’self-perceptions was evaluated for variations in content and social context. Adolescent self-disclosure to parents about academic achievement was also explored. Results indicated that parent-adolescent agreement was stronger with mothers than fathers and for aspects of self-knowledge that make direct inferences about abilities (performance, talent) rather than indirect inferences (effort, task difficulty) in both Mathematics and English. Results were similar in coed and single-sex contexts. Adolescent self-disclosure to parents suggested an important addition to the model of family influences on the adolescents’sense of academic achievement.
Circadian Organization and Photoreception in an Australian Dasyurid Marsupial (Sminthopsis macroura)
Authors: Cassone Vincent M.
Published: March 2007

Much is known about the formal properties of circadian rhythm regulation and the physiological substrates underlying rhythmicity in nocturnal rodents, but relatively few studies have addressed circadian rhythm regulation in other mammalian taxonomic groups. In this study, some formal and functional aspects of circadian organization in a nocturnal dasyurid marsupial, the stripe-faced dunnart (Sminthopsis macroura), were analyzed. To determine phasic responses to discrete pulses of light, dunnarts were placed in constant darkness (DD) and were periodically administered pulses of bright light at different times of the animals' circadian day. Analysis of phase shifts in response to light indicated a phase response curve that was similar to responses observed in nocturnal rodents. To determine the possibility of extraretinal photoreception mediating photic entrainment, dunnarts were anesthetized and orbitally enucleated while maintained in a light-dark regimen (LD 14:10). All blinded dunnarts free-ran with periods (τ) that were similar to those observed in DD, indicating that entrainment is mediated through ocular photoreception. However, the data also indicated a decrease in activity in blind dunnarts during the last 3-5 hr of the dark phase, raising the possibility of some retention of photoreceptive capacities.
Precise Annual Changes in the Numbers of "Synaptic" Ribbons and Spherules in the Rat Pineal Gland
Authors: Karasek M. , Lewinski A. , Vollrath L.
Published: March 2007

Although pineal "synaptic" ribbons (SR) are frequently examined by means of quantitative electron microscopy, their functional significance remains unclear. The same is true for related structures—"synaptic" spherules (SPH). In the course of such studies, it has been noted that SR counts may differ from laboratory to laboratory. Because seasonal changes may play a role, a 2-year study was performed on male rats kept under routine laboratory conditions and killed at monthly intervals during daytime or nighttime.

Both structures examined showed distinct day-night differences throughout the year, with higher numbers at night than during the day. There were significant annual changes in both SR and SPH during both daytime and nighttime. The comparison of the curves from the 2 years showed that they were virtually identical both during daytime and nighttime. The numbers of SR were the highest in October and the lowest in April; the numbers of SPH had two plateaus, one with lower values from November to April, and the other with higher values from May to October.

It appears from the present study that SR and SPH numbers in the rat pineal gland show statistically significant and precisely timed seasonal changes that may well account for the variations of SR numbers in the different publications.
Entrainment of the Melatonin Rhythms in Early Postnatal Lambs and Their Mothers
Authors: Wood Ruth I. , Claypool Lee E. , Ebling Francis J. P. , Foster Douglas L.
Published: March 2007

Although the developing sheep can produce an appropriately timed melatonin rhythm as early as 1 week after birth, it is not known whether the lamb is able to adjust its melatonin rhythm to a change in daylength. The ability of the young lamb to entrain its pattern of melatonin secretion to a new photoperiod was determined in the present study. Eight female lambs and their mothers were raised in long days (LD 16:8) beginning 2 weeks post partum. At 7 weeks of age, the time of lights-off was advanced 8 hr, the short-day photoperiod then being LD 8:16; the time of lights-on remained unchanged. Concentrations of melatonin were measured in blood samples collected hourly on days - 1, 0, 2, 4, 6, and 13 relative to the light change. On day 0, all mothers and daughters had advanced the onset of melatonin secretion by at least 1 hr, and by day 13, 12 of 16 had completely entrained to the new photoperiod. The rate of entrainment among individuals varied; the mean rate for lambs and mothers did not differ. This study provides evidence that the melatonin-rhythm-generating system matures shortly after birth.
Forced Dissociation of Activity Entrained to T Cycles of Food Access in Rats with Suprachiasmatic Lesions
Authors: Stephan Friedrich K.
Published: March 2007

The ability of rats with suprachiasmatic lesions to entrain anticipatory wheel run ning to two food access times per day was investigated. In the presence of meal schedules with periods of 23.75 hr and 24 hr, two of seven rats entrained activity to both for many consecutive days, while other rats repeatedly shifted activity from one schedule to the other. A second group of rats was maintained on 25-hr and 26-hr meal schedules. One of nine rats showed prolonged entrainment to both schedules (i.e., forced dissociation). In the other rats, antici patory activity (AA) waxed and waned repeatedly on each schedule. In both experiments, AA to the leading schedule increased when the interval between meals was about 5 hr or less, and AA to the trailing schedule diminished or ceased. Changes in AA were also common when the interval between meals was between 11 and 16 hr. The results are consistent with the hypoth esis that entrainment of AA to periodic food access is mediated by at least two mutually coupled circadian pacemakers. Interactions between these putative pacemakers appear to be strongest when the pacemakers are nearly in phase or in antiphase.
Annual Rhythm of Human Reproduction: II. Environmental Correlations
Authors: Roenneberg Till , Aschoff Jürgen
Published: March 2007

Annual rhythms of human conception rates (based on a worldwide selection of statistics) were correlated with photoperiod, monthly averages of daily hours of sunshine, minimum and maximum temperature, and humidity. Our results show for the first time on a global scale that photoperiod, as shown for many animals, may also influence the physiology of human reproduction. At higher latitudes, where changes in daylength are pronounced, a steep increase in human conceptions coincides with the vernal equinox. Temperature also appears to be a major influencing factor. Conception rates are above the annual mean at temperatures between 5° and 20°C, and temperature extremes decrease the probability of conceptions. In regions with cold winters and moderate summers, the number of conceptions correlates positively with temperature; close to the equator, where winters are more moderate than the hot summers, this correlation is negative. Regions with both hot summers and cold winters tend to have a bimodal conception rhythm. The influence of photoperiod is dominant before 1930, whereas the impact of temperature dominates in later years. With industrialization, people are increasingly shielded from both photoperiod (by indoor work) and temperature (by heating and air conditioning), which may explain the deseasonalization of the human conception rhythm. Photoperiod and temperature and the specific changes in their impact can account for several features of the annual human conception rhythm: latitude dependence, waveform, phase and amplitude, and their specific changes over time.
Differential Effects of Short Photoperiod on the Release of Progesterone and Testosterone by Hamster Testes In Vitro
Authors: Bartke Andrzej , Chandrashekar Varadaraj , Amador Armando G.
Published: March 2007

Suppression of testicular activity in hamsters and voles exposed to constant darkness or short photoperiod is associated with reduced ability of the testes to convert C21 steroid precursors to C19 androgens. In the present study, we have examined the time course of changes in testicular secretion of progesterone and testosterone in vitro in adult male golden hamsters exposed to short photoperiod. Gradual decrease in testicular weight after 1, 2, and 3 months of exposure to short photoperiod was accompanied by significant increase in the amount of progesterone released per milligram of testicular tissue in response to gonadotropin stimulation. In contrast, testosterone response to gonadotropic stimulus progressively decreased. These results suggest that photoperiod-related gonadal atrophy may be accompanied by reduced activity of the 17 α-hydroxylase: C17,20-lyase enzyme complex in the testes, and that seasonal transitions between the states of reproductive activity and quiescence involve changes in both the amount of steroids produced by the testes and the relative proportions of testosterone and its precursors.
"Demasking" the Temperature Rhythm after Simulated Time Zone Transitions
Authors: Folkard S. , Minors D.S. , Waterhouse J.M.
Published: March 2007

Simulated time zone transitions were performed in an isolation unit upon groups of one to four human subjects. In the first series of experiments, the adjustment of the circadian rhythm of body temperature, measured in the presence of sleep and other masking factors, was assessed by cosinor analysis and by cross-correlation methods. These methods modeled the circadian timing system either as a single component or as the sum of two components, those due to exogenous and endogenous influences. The one-component models described a more rapid adjustment of the temperature rhythm to the time zone transition than did the two-component models; we attribute this difference to the masking effects of the exogenous component. In a second series of experiments, we showed that the shift of the endogenous component, as assessed by the two-component models, was not significantly different from that measured during constant routines. The results also showed that, if the zeitgebers were phased in advance of the endogenous component, then advances of the endogenous component were produced only if this mismatch was less than about 10 hr. Mismatches greater than this, and cases where the zeitgebers were delayed with respect to the endogenous component, both produced delays of the endogenous component. We conclude that the two-component cross-correlation methods can be used to estimate shifts of the endogenous component of a circadian rhythm in the presence of masking factors. They are therefore an alternative to constant routines when these latter are impracticable to carry out.
Feedback in the Rabbit's Central Circadian System, Revealed by the Changes in Its Free-Running Food Intake Pattern Induced by Blinding, Cervical Sympathectomy, Pinealectomy, and Melatonin Administration
Authors: Bobbert A.C. , Riethoven J.J.
Published: March 2007

Long-term records of the number of food approaches per 30 min were obtained from 16 rabbits in constant light and after blinding. Optic nerve sectioning usually resulted in a shortening of the free-running period (τ; mean reduction = -0.26 hr) of the oscillator governing the rabbit's food intake pattern. Subsequent resection of both superior cervical ganglia always reduced this τ (mean = -0.41 hr), and it could be further shortened (mean = -0.24 hr) by chronic administration of melatonin. These observations led to experiments in which the food intake of 15 blinded rabbits was recorded before and after pinealectomy. This always resulted in a lengthening of τ (mean = +0.27 hr), which was never seen after subtotal or sham pinealectomy in 10 other blinded animals (mean = -0.05 hr). Sympathectomy also reduced τ (mean = -0.50 hr) in the pinealectomized rabbits, whereas it induced a smaller reduction (mean = -0.29 hr) after sham pinealectomy. These results, together with previous observations on the effect of sympathectomy on the retinal "dark" discharge and on the influence of the latter upon the food intake pattern, indicate that the cervical sympathetic nerves may form part of three feedback loops for the rabbit's central circadian system. These have separate postganglionic pathways; there are also differences in the circadian phasing of their activities and in their effects on τ.
Sensitivity of Syrian Hamsters (Mesocricetus auratus) to Amplitudes and Rates of Photoperiodic Change Typical of the Tropics
Authors: Heideman Paul D. , Bronson F.H.
Published: March 2007

Empirical data suggest that reproductive photoresponsiveness occurs in some populations of mammals above 13° of latitude, but may be absent in populations from 0° to 10° of latitude. The present experiments examined the degree to which the low amplitude of change in photoperiod in the tropics constrains mammals from using daylength as a seasonal cue. The Syrian hamster, a temperate-zone species, was studied because of its well-documented ability to respond to small changes in photoperiod, and because of the absence of an alternative robustly responding species from the tropics. We subjected adult male hamsters to photoperiods that mimicked the amplitude and rate of photoperiod change of 30°, 20°, 10°, and 5° of latitude, but centered around an estimate of their critical daylength. For comparison, a fifth group was subjected to an abrupt change in daylength of a magnitude equal to the total annual variation occurring at 30°. The two groups experiencing the gradually changing daylengths of 30° and 20° showed less within-group synchrony during testicular regression; in other dimensions of the annual testis cycle, including the degree of synchrony exhibited during recrudescence, they reacted similarly to the hamsters given the abrupt change in daylength. Some of the hamsters exposed to the gradually changing daylengths of 10° responded to this challenge, as did a few in the 5° treatment-in both cases, with poor within-group synchrony and a submaximal decrease in testis size. In an abbreviated second experiment, hamsters given abrupt decreases in daylength of magnitudes equal to those of the 10° and 5° groups responded slightly more frequently, and with maximal decreases in testis size. This suggests that mammals may not be constrained absolutely by an inability to respond to changes in photoperiod at 5° to 10° latitude. Seasonally breeding populations of mammals in the deep tropics that do not use photoperiod to regulate reproduction may use nonphotoperiodic cues because they offer a higher signal-to-noise ratio than do tropical changes in photoperiod.
The Effects of Evening Bright Light on Next-Day Sleep Propensity
Authors: Tzischinsky Orna , Lavie Peretz
Published: March 2007

The present study investigated the effects of evening bright light (BL) compared to dim light (DL) on next-day sleep propensity as well as the acrophase of oral temperature and mood scores. A total of 12 male subjects (mean age 23.5 ± 2.6 years) were exposed to 2 h of evening DL or BL 30 min after sunset for 5 consecutive days. The experimental period started after the 5th day of exposure. After light exposure, subjects remained awake in the sleep laboratory until 07:00 h, when they began the 7/13 ultrashort sleep-wake paradigm, which continued for 24 h until 07:00 h the next day Oral temperature was measured hourly The results showed that evening exposure to BL, in comparison to DL, significantly delayed the next-day sleep gate as well as the acrophase of the oral temperature curve and the acrophase of negative mood. The effects of BL on the next-day distribution of sleep stages showed an increase of Stage 2 and less REM (rapid eye movement) during the morning. The results indicate that sleep propensity is regulated by a circadian pacemaker that is responsive to evening BL exposure.
Estimating the Endogenous Circadian Temperature Rhythm without Keeping People Awake
Authors: Carrier Julie , Monk Timothy H.
Published: March 2007

This study was concerned with estimating endogenous temperature rhythms without imposing sleep deprivation. The aim of Experiment 1 was to quantify the masking effect on the circadian temperature rhythm in a group of 18 healthy young subjects (8 women and 10 men, ages 19-29 years). Temperature data collected under a 36-h wakeful bed rest protocol were used as a marker of the endogenous component of the rhythm ("unmasked rhythm"), and tempera ture data collected under 24 h of a normal nycthemeral routine (immediately before the bed rest protocol) were used as the "masked" rhythm. An algorithm to "demask" the temperature data collected under the nycthemeral condition was then developed, based on the differences observed between the temperature data collected under wakeful bed rest and nycthemeral conditions. The consis tency of the demasking technique was tested in Experiment 2, using the same parameters on a group of 19 healthy elderly subjects (8 women and 11 men, ages 78-88 years) who also had experienced both nycthemeral and wakeful bed rest conditions. The demasking technique was evaluated both by comparing nycthe meral, demasked, and unmasked temperature rhythms themselves and by com paring individual estimates of circadian phase and amplitude that had been gleaned from them. In comparison to the unmasked condition, the nycthemeral condition showed lower mean nighttime temperature, earlier mean phase esti mates, and higher mean amplitude estimates in both young and elderly subjects. Following application of the demasking procedure to the nycthemeral tempera ture data, mean demasked temperature curves were closely comparable to mean unmasked temperature curves in both young and elderly subjects. Phase and amplitude estimates derived from the demasked temperature data also were highly comparable to those in the unmasked conditions. Thus, this demasking procedure appears to be a useful tool in estimating the endogenous temperature rhythm and appears to work equally well for young and elderly subjects.