Modelling human immunodeficiency virus ribonucleic acid levels with finite mixtures for censored longitudinal data

The measurement of human immunodeficiency virus ribonucleic acid levels over time leads to censored longitudinal data. Suitable models for dynamic modelling of these levels need to take this data characteristic into account. If groups of patients with different developments of the levels over time are suspected the model class of finite mixtures of mixed effects models with censored data is required. We describe the model specification and derive the estimation with a suitable expectation-maximization algorithm. We propose a convenient implementation using closed form formulae for the expected mean and variance of the truncated multivariate distribution. Only efficient evaluation of the cumulative multivariate normal distribution function is required. Model selection as well as methods for inference are discussed. The application is demonstrated on the clinical trial ACTG 315 data.     

Consolidated findings from 6 years research on the age-differentiated design of human-computer interaction

The fast aging of many western and eastern societies and their increasing reliance on information technology create a compelling need to reconsider older users' interactions with computers. This paper summarizes the results of 6 years of research on the age-differentiated design of human-computer interaction. The well-known model of human information processing served as the theoretical framework. The model components 'sensory processing', 'perception', 'working memory', 'decision and response selection' and 'response execution' were analyzed exemplarily in task settings on project management. In seven empirical studies with a total number of 405 participants between 20 and 77 years the human-computer interaction was analyzed regarding effectiveness, efficiency and user satisfaction. For most but not all studies the results reveal that age-induced differences in human-computer interaction can best be compensated by an ergonomic 'design for all'. In some cases however an age-specific approach is favorable.     

The Nonprofit Catallaxy: An Austrian Economics Perspective on the Nonprofit Sector

This paper examines the nonprofit sector from the perspective of the Austrian school of economic thought. In contrast to the traditional market failure approach, the Austrian school locates the role of the nonprofit sector in the facilitation of the spontaneous order and the utilization of local dispersed knowledge about the societal needs through a Hayekian “discovery procedure.” Another contribution of the Austrian school is in calling attention to the “calculation challenge” faced by the nonprofit sector, i.e., the reduced role of monetary signals as the informational basis for decision making. The calculation challenge brings up the important issue of societal feedback mechanisms operating in the nonprofit sector. It is shown that, in the nonprofit sector context, this challenge takes the form of the accountability problem.     

Accommodating ‘foreigners’: narrative accounts of Berlin's German-born Turkish Ausländer

This paper examines the discursive messages conveyed through everyday encounters among German-born Turkish Ausländer (foreigners) and ethnic Germans in Berlin. Using narrative analysis, I explore how these messages operate to maintain a series of separate and unequal social relations based on gender, ethnicity, religion, and skin colour. The personal experiences of local residents illustrate how these discourses serve to mark some Ausländer as less threatening than others, some as preferable, and others as undesirable. Some Ausländer are also considered more valuable than others, and the status of one often depends on the superior or subordinate status of the other. Through exploring these complexities as experienced by local informants, this paper shows the importance of certain interactive processes that construct Ausländerness in varying ways, while still defining people's identities in relation to norms that privilege the dominant subjects.     

Manual flying skills under the influence of performance shaping factors

This paper describes an experimental study investigating pilots' manual flying skills. In today's line oriented flight training, basic flying skills are neglected frequently. So, the study examines the manual flying skills of commercial airline pilots under the influence of several performance shaping factors like training, practice or fatigue in a landing scenario. The landing phase shows a disproportionate high percentage of aircraft accidents and it is typically flown by hand. The study is to be undertaken with randomly selected pilots in a full motion flight simulator to ensure a high validity of the results.     

Turkish Capitalist Modernity and the Gezi Revolt

In this paper an attempt is made to reassess how and why the laic/Islamic dual opposition has come to be a decisive factor in the politics of Turkish capitalist modernity. The question as to whether this opposition may survive into the twenty‐first century is briefly discussed. It is noted that in the aftermath of the prolonged confrontation between the emergent imagined community of the Gezi Revolt and the Islamist AKP government, a religiously neutral political identity came into sight in public life, which can be considered as the harbinger of a new kind of social individuality, one which is incommensurate with the laic/Islamic dual opposition.     

Evaluation of objectivity, reliability and criterion validity of the key indicator method for manual handling operations (KIM-MHO), draft 2007

Upper extremity musculoskeletal symptoms and disorders are common in the working population. The economic and social impact of such disorders is considerable. Long-time, dynamic repetitive exposure of the hand-arm system during manual handling operations (MHO) alone or in combination with static and postural effort are recognised as causes of musculoskeletal symptoms and disorders. The assessment of these manual work tasks is crucial to estimate health risks of exposed employees. For these work tasks, a new method for the assessment of the working conditions was developed and a validation study was performed. The results suggest satisfying criterion validity and moderate objectivity of the KIM-MHO draft 2007. The method was modified and evaluated again. It is planned to release a new version of KIM-MHO in spring 2012.     

The relevance of temporal iconicity with instruction manuals for elderly users

Gerontolinguistic obtains a growing importance with the increase of elderly users due to Demographic Change. Since acceptance and ease of use of supportive systems for elderly, such as "E-Nursing-Assistants", are highly dependent on the age suitable design of readable instructions, an age-appropriate linguistic concept is of high value for usability. There has been only little research on the relevance of foreign words, signal words, textual arrangement, optical accentuation of key terms and temporal iconicity concerning older users. Thus, an efficient design of age suitable manual instructions within a medical context still remains to be done. The objective of this research was to evaluate the relevance of the previously mentioned factors in the context of written instructions. For this, an empirical survey was designed which was given to 45 study participants. The subjects of the experiment were given 4x3 instructions after a pretest questionnaire. The aim was to execute these instructions as correctly and quickly as possible. Furthermore the instructions were rated regarding comprehensibility with a retrospective questionnaire.     

The effects of teenage childbearing on long-term health in the US: a twin-fixed-effects approach

This paper explores the effect of teenage childbearing on long-term health outcomes and behaviors of mothers using the Midlife Development in the US dataset. Within-family estimations, using samples of siblings, and twin pairs, are employed to overcome the bias generated by unobserved family background and genetic traits. The results suggest no significant effects on health outcomes, and modest effects on health behaviors, including exercise and preventive care. However, accounting for life-cycle effects demonstrates that teenage childbearing has significant effects on both health outcomes and behaviors early in life, but very few significant effects later in life. Moreover, teenage childbearing has a particularly acute effect among minorities. Finally, this paper provides evidence that the effects operate through reduced income and labor force participation, and matching with a lower “quality” spouse.     

Urban and peri-urban agriculture and its implication on food and nutrition insecurity in northern Ghana: a socio-spatial analysis along the urban–rural continuum

Food and nutrition insecurity remains a challenge in sub-Saharan Africa. Several studies have examined food and nutrition insecurity in urban or rural areas but have not captured the whole continuum. Between November and December 2013, 240 households were surveyed along the urban–rural continuum in Northern Ghana. The study objective was to understand the socio-spatial dynamics of household food and nutrition insecurity and to investigate the role played by urban, peri-urban and rural agriculture. The study found that there was more involvement in agriculture in rural areas compared to peri-urban areas and urban areas. Households from urban areas were more food insecure (HFIAS >?11) compared to their counterparts in peri-urban and the rural areas. Stunting increased by 3.4 times (p?=?0.048) among households located in the peri-urban area. Wasting was reduced by 0.16 times among household that produced staple food or vegetables (p?=?0.011). Overweight was reduced by 0.04 times among households that produced livestock (p?=?0.031). The results reveal a socio-spatial dimension of food and nutrition insecurity that is related to agricultural activities.