An Ecological Model for Quantitative Risk Assessment for Schistosomiasis: The Case of a Patchy Environment in the Coastal Tropical Area of Northeastern Brazil

We developed a stochastic model for quantitative risk assessment for the Schistosoma mansoni (SM) parasite, which causes an endemic disease of public concern. The model provides answers in a useful format for public health decisions, uses data and expert opinion, and can be applied to any landscape where the snail Biomphalaria glabrata is the main intermediate host (South and Central America, the Caribbean, and Africa). It incorporates several realistic and case‐specific features: stage‐structured parasite populations, periodic praziquantel (PZQ) drug treatment for humans, density dependence, extreme events (prolonged rainfall), site‐specific sanitation quality, environmental stochasticity, monthly rainfall variation, uncertainty in parameters, and spatial dynamics. We parameterize the model through a real‐world application in the district of Porto de Galinhas (PG), one of the main touristic destinations in Brazil, where previous studies identified four parasite populations within the metapopulation. The results provide a good approximation of the dynamics of the system and are in agreement with our field observations, i.e., the lack of basic infrastructure (sanitation level and health programs) makes PG a suitable habitat for the persistence and growth of a parasite metapopulation. We quantify the risk of SM metapopulation explosion and quasi‐extinction and the time to metapopulation explosion and quasi‐extinction. We evaluate the sensitivity of the results under varying scenarios of future periodic PZQ treatment (based on the Brazilian Ministry of Health's plan) and sanitation quality. We conclude that the plan might be useful to slow SM metapopulation growth but not to control it. Additional investments in better sanitation are necessary.     

Unraveling quantity discounts

We consider the situation in which a buying organization deals with a discrete quantity discount schedule offered by a selling organization. Furthermore, the buying organization can negotiate with the selling organization about the lot size and purchase price, but does not know the underlying function that was used by the selling organization to determine the quantity discount schedule. In this paper, we provide an analytical and empirical basis for one general quantity discount function (QDF) that can be used to describe the underlying function of almost all different quantity discount types. We first develop such a QDF analytically. Among other things, this QDF enables buying organizations to calculate detailed prices for a large number of quantities. We subsequently show that the QDF fits very well with 66 discount schedules found in practice. We discuss that the QDF and related indicators can be a useful tool in supplier selection and negotiation processes. It can also be used for competitive analyses, multiple sourcing decisions, and allocating savings for purchasing groups. Additionally, the QDF can be included in research models incorporating quantity discounts. We conclude the paper with an outlook on further QDF research regarding the characterization of commodity markets from a demand elasticity point of view.     

Characteristics of a central change programme within a governmental bureaucracy: a grounded theory study

Purpose The purpose of the paper is to present a theory of organisational change within the setting of a governmental bureaucracy. Design/methodology/approach Orthodox grounded theory is employed in the setting of a change programme in 12 Audit departments of the Dutch Ministries (public-sector). Findings The examined organisational change has specific characteristics. The Dutch ‘ministerial autonomy’ and the clearly recognizable role types of the key figures involved have a strong impact on the change programme and the realisation of its goals. Research limitations/implications Findings are derived on the basis of a substantive case study of the change programme of the Dutch Departmental Audit function. The research sheds new light on characteristics related to the occupational group of Chartered Accountants and characteristics of a governmental bureaucracy and it helps to understand change programmes within this bureaucracy. Practical implications The grounded theoretical model draws attention to the impact of key figures and circumstances on a change programme within the central government. Originality/value The paper builds on theories of organisational change but applies them in the typical context of the Dutch civil service where ministerial autonomy, on the one hand, and a move in the direction of more centrally organised activities (concern idea), on the other, require a difficult balancing act of all players in the change arena.     

Predictive factors of acculturation attitudes and social support among Asian immigrants in the USA

This study examines acculturation attitude and its relation to social support among Asian immigrants. The data were collected from 242 Korean, Indian and Filipino immigrants in the USA using the Acculturation Attitude Scale and the Social Support Index. Findings showed that Koreans had a less positive attitude toward acculturation than did Indian and Filipino participants. Acculturation attitude was positively correlated with educational level and English fluency. This study also found a negative correlation between acculturation attitude and social support. Social support from friends and English fluency were identified as significant predictor variables in determining the level of acculturation attitude. These findings not only contribute to social work education and practice, but also increase cultural sensitivity and awareness in working with these populations.     

Young Moroccan-Dutch: Thinking in Dutch,Feeling Moroccan

Abstract

We examined to what extent Moroccan-Dutch (N?=?25) between 15 and 32 years of age are oriented towards the Dutch and Moroccan community when describing their identities. We used the Twenty Statements Test (developed by Kuhn and McPartland (1954). See, M. H. Kuhn and T. S. McPartland, “An Empirical Investigation of Self-attitudes”, American Sociological Review, Vol. 19, No. 1, 1954, p. 69. In this study, participants were asked to complete the sentence with ‘I am..’ 20 times to assess how they described themselves.) and in-depth interviews to understand their challenges on the acculturation path since many face disadvantage and exclusion in the Dutch community. Moroccan-Dutch were, compared to the reference groups of mainstream Dutch (N?=?20) and Moroccans (N?=?25), more proud of their ethnic identity and attached to Islam. Though their Dutch language was dominant, they felt more Moroccan. They praised the Dutch openness, but suffered from negative stereotyping. Their participation in the Dutch community was low. To enhance their position, social professionals working with Moroccan-Dutch could draw on the rich ethnic and faith traditions of this group to encourage their deeper engagement with the Dutch society.     

Network Embeddedness in Exploration and Exploitation of Joint R&D Projects: A Structural Approach

This paper analyses how network embeddedness affects the exploration and exploitation of R&D project performance. By developing joint projects, partners and projects are linked to one another and form a network that generates social capital. We examine how the location, which determines the access to information and knowledge within a network of relationships, affects the performance of projects. We consider this question in the setup of exploration and exploitation projects, using a database built from an EU framework. We find that each of the structural embeddedness dimensions (degree, betweenness and eigenvector centrality) have a different impact on the exploration and exploitation project performance. Our empirical analysis extends to project management literature and social capital theory, by including the effect that the acquisition of external knowledge has on the performance of the project.     

A Necessary Condition for the Strong Oracle Property

A problem of using a non‐convex penalty for sparse regression is that there are multiple local minima of the penalized sum of squared residuals, and it is not known which one is a good estimator. The aim of this paper is to give a guide to design a non‐convex penalty that has the strong oracle property. Here, the strong oracle property means that the oracle estimator is the unique local minimum of the objective function. We summarize three definitions of the oracle property – the global, weak and strong oracle properties. Then, we give sufficient conditions for the weak oracle property, which means that the oracle estimator becomes a local minimum. We give an example of non‐convex penalties that possess the weak oracle property but not the strong oracle property. Finally, we give a necessary condition for the strong oracle property.     

Investigating impacts of complex sampling on latent growth curve modelling

We investigate the impacts of complex sampling on point and standard error estimates in latent growth curve modelling of survey data. Methodological issues are illustrated with empirical evidence from the analysis of longitudinal data on life satisfaction trajectories using data from the British Household Panel Survey, a national representative survey in Great Britain. A multi-process second-order latent growth curve model with conditional linear growth is used to study variation in the two perceived life satisfaction latent factors considered. The benefits of accounting for the complex survey design are considered, including obtaining unbiased both point and standard error estimates, and therefore correctly specified confidence intervals and statistical tests. We conclude that, even for the rather elaborated longitudinal data models that were considered, estimation procedures are affected by variance-inflating impacts of complex sampling.     

Cultural capital or relative risk aversion? Two mechanisms for educational inequality compared1

In this paper we empirically examined two explanatory mechanisms for educational inequality: cultural reproduction and relative risk aversion, using survey data taken from secondary school pupils in Amsterdam. Cultural reproduction theory seeks to explain class variations in schooling by cultural differences between social classes. Relative risk aversion theory argues that educational inequalities can be understood by between-class variation in the necessity of pursuing education at branching points in order to avoid downward mobility. We showed that class variations in early demonstrated ability are for a substantial part cultural: cultural capital - measured by parental involvement in highbrow culture - affected school performance at the primary and secondary level. However, relative risk aversion - operationalized by being concerned with downward mobility - strongly affects schooling ambitions, whereas cultural capital had no effect. Thus, we conclude that 'primary effects' of social origin on schooling outcomes are manifested through cultural capital and not through relative risk aversion (in addition to other potential sources of class variations such as genetics). Relative risk aversion, and not cultural capital, affects schooling ambitions, which is relevant for our understanding of secondary effects.     

The self-perceptions and interpersonal relationships of persons with significant physical disabilities: a qualitative pilot study

This exploratory, qualitative research was conducted to obtain the perspectives of people with significant physical disabilities regarding factors that have facilitated and hindered the development of a positive self-concept, participation in the broader society, and the formation of interpersonal relationships. The sample was high achieving in terms of education and/or career and attributed positive self-perceptions and their success in the broader society and interpersonal relationships to the attitudes and perceptions regarding their abilities, talents, and potential modeled in supportive family relationships. Females reported the influence of significant others most often, and males the effectiveness of their personality characteristics. Societal barriers, both practical and attitudinal, were reported along with the process for developing a positive selfperception despite these.