The phenomenon of "anomalous" micellization is investigated in dilute solutions of two nearly symmetric poly(styrene-b-isoprene) diblock copolymers, via dynamic light scattering. In two polystyrene-selective solvents, diethyl phthalate and dimethyl phthalate, the critical micelle temperatures (cmt) are clearly determined by rather abrupt increases in the hydrodynamic radius and scattered intensity upon cooling; this corresponds to "normal" micellization. In contrast, for the same polymers dissolved in two polyisopreneselective solvents, tetradecane and squalane, anomalous micellization was consistently observed: the hydrodynamic radius exceeded 1000 Å and the intensity was unusually large, over a modest temperature interval just above the cmt. We propose that anomalous micellization is due to the incipient phase separation of small amounts of polystyrene homopolymer, resulting from incomplete crossover during the sequential anionic polymerization of styrene and isoprene. In one sample, the presence of homopolymer (ca. 1 wt % of copolymer) was confirmed by chromatography, and removal of this impurity eliminated the anomalous micellization. Addition of similar amounts of polyisoprene homopolymer to the same sample induced anomalous micellization in the polystyrene-selective solvents, with the onset of the effect corresponding to the cloud point for the polyisoprene homopolymer. These observations support the proposed hypothesis; the extent to which this hypothesis may extend to previous reports of anomalous micellization is discussed. LA0268808

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BackgroundBecause of the adverse environmental conditions present in less-resourced environments (LREs), the World Health Organization (WHO) has recommended that specialised wheelchair test methods may need to be developed to support product quality standards in these environments. A group of experts identified caster test methods as a high priority because of their common failure in LREs, and the insufficiency of existing test methods described in the International Organization for Standardization (ISO) Wheelchair Testing Standards (ISO 7176).ObjectivesTo develop and demonstrate the feasibility of a caster system test method.MethodBackground literature and expert opinions were collected to identify existing caster test methods, caster failures common in LREs and environmental conditions present in LREs. Several conceptual designs for the caster testing method were developed, and through an iterative process using expert feedback, a final concept and a design were developed and a prototype was fabricated. Feasibility tests were conducted by testing a series of caster systems from wheelchairs used in LREs, and failure modes were recorded and compared to anecdotal reports about field failures.ResultsThe new caster testing system was developed and it provides the flexibility to expose caster systems to typical conditions in LREs. Caster failures such as stem bolt fractures, fork fractures, bearing failures and tire cracking occurred during testing trials and are consistent with field failures.ConclusionThe new caster test system has the capability to incorporate necessary test factors that degrade caster quality in LREs. Future work includes developing and validating a testing protocol that results in failure modes common during wheelchair use in LRE.

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Professor Farazmand has provided the inspiration, guidance, and assistance without which this special issue would not have been published. He has provided leadership, support, encouragement, and constructive criticism that have caused us to insist that only articles of the highest substantive and editorial excellence are included.

Contracting-out for human services has become preferred public policy at all levels of government. This service delivery policy choice has important implications for accountability and for the ability of contracting nonprofit organizations to be flexible and innovative. Although the use of contracting has expanded dramatically in the human services since the 1970s, many important public management policy questions remain unasked and unanswered. This article raises and discusses nine largely unanswered questions that are central to the reasons why government continues to expand its dependence on contracted human services. These questions address key elements of a larger policy-of-public-management question: “Is it possible to achieve accountability and flexibility when government contracts-out for the provision of publicly funded human services?” By addressing these nine questions, we seek to determine what is known and not known about the key accountability issues in contracted public human services. We also attempt to highlight the importance of these questions and issues for public management policy, inter-sectorial organization theory, the practice of nonprofit and public organization management, and thus for research and theory development.