Sensitivity analysis of linear time-invariant compartmental models with steady-state constraint

Compartmental models have been widely used in modelling systems in pharmaco-kinetics, engineering, biomedicine and ecology since 1943 and turn out to be very good approximations for many different real-life systems. Sensitivity analysis (SA) is commonly employed at a preliminary stage of model development process to increase the confidence in the model and its predictions by providing an understanding of how the model response variables respond to changes in the inputs, data used to calibrate it and model structures. This paper concerns the application of some SA techniques to a linear, deterministic, time-invariant compartmental model of global carbon cycle (GCC). The same approach is also illustrated with a more complex GCC model which has some nonlinear components. By focusing on these two structurally different models for estimating the atmospheric CO₂ content in the year 2100, sensitivity of model predictions to uncertainty attached to the model input factors is studied. The application/modification of SA techniques to compartmental models with steady-state constraint is explored using the 8-compartment model, and computational methods developed to maintain the initial steady-state condition are presented. In order to adjust the values of model input factors to achieve an acceptable match between observed and predicted model conditions, windowing analysis is used.     

Hidden boundaries and shared meanings: the roles of researcher characteristics and cultural norms in shaping understandings of sexuality in the unstructured interview setting

This paper examines the role of the research process in shaping the construction of knowledge about sensitive topics in in-depth interviews particularly with regard to researcher identity and cultural influences or norms. We argue that these influences shape all aspects of the research process and that researchers will benefit from reflecting upon them when planning, undertaking and interpreting qualitative studies. Drawing on an empirical study interviewing Australian women aged 55 years and older about sexuality we address differences and similarities between researchers and participants; cultural constructions of sexuality and ageing, and generational influences. Using examples from our interview data we interrogate the contribution of each of these aspects to the interview dynamic and the co-production of meaning. Our analysis draws attention to the fluidity of insider and outsider status and to the existence of hidden boundaries that impact on how certain topics can be discussed in interviews. The paper argues that knowledge about sensitive topics such as older people’s sexuality must be viewed as a situated occurrence shaped by the particularities of the interview and the cultural context. Finally, we discuss the implications of these findings for qualitative inquiries into sensitive topics.     

Users as Citizens: Collective Action and the Local Governance of Welfare

Self-organization amongst users of community care services preceded the consumerist developments of the 1980s and early 1990s, but can be considered to have been "legitimized" by top-down objectives relating to "user involvement". Nevertheless, the objectives and value bases of disabled people's organizations and organizations of users (or survivors) of mental health services have not always been consistent with those of consumerism, and user groups have experienced tensions in determining the extent to which they should respond to official agendas. Drawing on theories of new social movements and of citizenship, this paper considers the developing place of user organizations within systems of local governance. It looks at the way in which groups have sought to assert the legitimacy both of experiential knowledge and of their position as citizens in the face of official responses which have constructed them as self-interested pressure groups. It draws on empirical research investigating local groups of disabled people and of mental health service users conducted in the first part of the 1990s. It discusses the significance of shared identity as a basis for collective action alongside more pragmatic motivations to influence the nature of health and social care services. In the context of appeals to "community" and "partnership" which are starting to replace the discourse of markets and contracts as the key metaphor for both policy-making and service delivery, the article considers likely future roles for groups comprising people often excluded from community.     

The Trajectory of Concurrent Motor and Vocal Behaviors Over the Transition to Crawling in Infancy

To document the trajectory of motor and vocal behaviors in real and developmental time, we observed infants at each of four biweekly naturalistic play sessions over the transition to crawling. An exhaustive and mutually exclusive coding scheme documented all vocalizations and postures. Odds ratios of the likelihood of a given posture‐vocalization dyad revealed that vocalization and crawling were significantly unlikely to co‐occur at the session marking the onset of crawling. We speculate that infants’ allocation of attention over the transition to crawling prompted behavioral trade‐offs. During mastery of a novel skill, infants may have had difficulty allocating attention to multiple tasks, but with experience, a decrease in attentional load for the new skill allowed performance of simultaneous behaviors in other domains to occur.     

“Dude,I’m Seventeen … It’s Okay Not to Have Sex by This Age”: Feelings,Reasons, Pressures,and Intentions Reported by Adolescents Who Have Not Had Sexual Intercourse

This study investigated feelings, reasons, pressures, and previous sexual experiences reported by students who have not had sexual intercourse and how these factors are associated with self-rated likelihood of having sex during the next year. Using data from the Fifth National Survey of Australian Secondary Students and Sexual Health (n = 783), this study found, in general, students had positive feelings about not having sex. Reasons for not having sex such as being proud to say no and not being ready were rated higher in importance than fear of potential outcomes or religious/cultural beliefs. Students reported limited pressure from parents and friends and, despite not having sexual intercourse, more than half of the sample had experienced some form of sexual activity. Stronger likelihoods of having sex during the next year were reported by students who had previously engaged in other sexual practices, reported more pressure from friends to have sex, and had negative feelings about not having sex. Sexuality educators can use these findings to guide approaches to sex education, emphasizing feelings, intentions, and reasoning over fear tactics. Discussion of a range of sexual practices will address more closely the experiences of young students as they begin their sexual lives.     

Annual Review: Practice and Research in Career Development and Counseling—1995

The author reviews and summarizes more than 200 articles related to career development issues that were published in 1995. The goals were to identify articles relevant to clinicians and to provide a comprehensive and coherent overview of the career development literature. The articles were reviewed and organized within seven areas: counselor-client relations, business and industry, university career centers, career development theories, gender differences, work and family issues, and cross-cultural issues. Implications for future research directions and for assisting clients with their career development challenges are discussed.     

Psychological Wellbeing Among Same‐sex Attracted and Heterosexual Parents: Role of Connectedness to Family and Friendship Networks

Increasing numbers of lesbian, gay and bisexual (LGB) adults are entering into parenthood. Previous studies indicate many of these parents receive little or no support from their families of origin due to family members' negative attitudes toward homosexuality. This study looks at the extent to which LGB parents report a lower sense of connectedness to family of origin and friendship networks than heterosexual parents and whether this has an impact on psychological wellbeing in either of these groups. Data were derived from two studies of parents: Work, Love, Play, a study of Australian and New Zealand LGB parents (n=324); and the Longitudinal Study of Australian Children, a population‐based study of young children and parents (n=6460). Structural equation modelling was used to explore the relationships between: parent sexuality and family/friendship connectedness, family/friendship connectedness and psychological wellbeing, parent sexuality and psychological wellbeing. LGB parents reported feeling less connected to their families of origin but more connected to their friendship groups than heterosexual parents. Counter to previous studies, we found no difference in the psychological wellbeing of LGB parents compared to heterosexual parents when examining the direct effect of sexuality on psychological wellbeing. Clinical implications for counsellors and family therapists are discussed.     

Number of matches and matched people in the birthday problem

The well known birthday problem asks for the probability of at least one match out of a group of n people. Also of interest are the number of matches and the number of matched people. In this paper the means and variances of the number of matches and matched people are obtained. A generalization of the use of these methods to computer storage analysis is discussed.