Regulation of ovarian function by the TGF-beta superfamily and follistatin

The role of follistatin as an activin-binding protein has dominated the study of this molecule for the last 10 years. However, there is emerging evidence that follistatin has a role in modulating the biology of other members of the transforming growth factor beta (TGF-beta) superfamily. This review summarizes the current concepts encompassing follistatin biochemistry as well as molecules with which it is functionally associated. Moreover, the importance of the two follistatin isoforms (follistatin-288 and follistatin-315) is discussed with particular emphasis on the regulation of the ovary. In addition to activin, this review discusses the functions of other members of the TGF-beta superfamily, for example growth differentiation factor 9 (GDF-9), bone morphogenetic protein 15 (BMP-15), BMP-6, BMP-4 and BMP-7, in the ovary, and the potential interactions between follistatin and these growth factors. The complex network of TGF-beta superfamily growth factor members involved in the modulation of ovarian function and the interactions of follistatin with these proteins is highlighted.     

An intake of americium oxide powder: implications for biokinetic models for americium

A worker inhaled 241AmO2 powder. Air sampling showed low activities but a nose blow revealed 92 Bq. Results from faecal sampling and lung and whole-body monitoring indicated an intake of about 200 Bq, but urine sampling, though commencing only 1 d after intake, showed below-threshold activities (< 0.2 mBq). This conflicts with predictions based on the ICRP Publication 67 biokinetic model for americium and the ICRP Publication 66 model for the human respiratory tract, if default lung parameters are used.     

New Linear Program Performance Bounds for Closed Queueing Networks

We develop new linear program performance bounds for closed reentrantqueueing networks based on an inequality relaxation of the averagecost equation. The approach exploits the fact that the transitionprobabilities under certain policies of closed queueing networksare invariant within certain regions of the state space. Thisinvariance suggests the use of a piecewise quadratic functionas a surrogate for the differential cost function. The linearprogramming throughput bounds obtained are provably tighter thanpreviously known bounds at the cost of increased computationalcomplexity. Functional throughput bounds parameterized by thefixed customer population N are obtained, alongwith a bound on the limiting throughput as N + .We show that one may obtain reduced complexity bounds while stillretaining superiority.     

The Doomsday distributed termination detection protocol

Distributed termination detection (DTD) algorithms are important since they detect globally stable states in distributed computations. Here we introduce a new DTD mechanism, the Doomsday protocol together with its proof of correctness. Doomsday is generic since it forms the basis for a number of new and existing DTD algorithms for which the correctness proof may be reused. The paper describes the Doomsday protocol, provides its formal proof, derives one new DTD algorithm and shows how other hitherto unrelated algorithms, Dijkstra–Scholten, Task Balancing and Credit Recovery, can be derived from the protocol. The paper concludes by examining various properties of the protocol in the context of existing DTD algorithms. This work was supported in part by Visiting Fellowship grant EPSRC GR/R84481/01 “The Doomsday Protocol” and by Australian Research Council ARC Linkage International Grant LX0349049 “Extending a Family of Garbage Collectors”.     

Weathering wikis: Net-based learning meets political science in a South African university

Wikis represent flexible tools functioning as open-ended environments for collaboration while also offering process and group writing support. Here we focus on a project to innovate the use of wikis for collaborative writing within student groups in a final-year undergraduate political science course. The primary questions guiding our research were in what ways could wikis assist collaborative learning in an undergraduate course in political science and how we could support educators’ in the effective use of wikis? Curiously, wikis may serve as a mediating artifact for collaborative writing even among students who are reluctant to post online drafts. The paper raises questions concerning the nature and limits of lecturer and tutor power to deliver transformative educational innovations in relation to the capacity of students to embrace, comply with, or resist such innovation. In analysing the negotiation of the use of wikis in the course by and among the lecturer, tutors, and students, we draw on two principles in activity theory, which Yrjö Engeström argued are central to his model of expansive learning: multi-voicedness and contradictions [Engeström, Yrjö. (1987). Learning by expanding: An activity-theoretical approach to developmental research. Helsinki: Orienta-Konsultit; Engeström, Yrjö. (2001). Expansive learning at work: Toward an activity theoretical reconceptualization. Journal of Education and Work14(1), 133-156.]. We add a third principle, transparency, to more fully capture what we observed.     

Disentangling role perceptions: How perceived role breadth, discretion, instrumentality, and efficacy relate to helping and taking charge.

The objective of this study was to empirically disentangle role perceptions related to organizational citizenship behavior (OCB) that have been confounded in past research, investigate their unique relationships with both an affiliative (helping) and a challenging (taking charge) form of OCB, and determine their relative importance in explaining these 2 forms of OCB. The authors also examined whether role discretion and role breadth independently moderate the procedural justice-to-OCB relationship. The authors surveyed 225 engineers in India and their direct supervisors. The results showed that 3 of the 4 facets of OCB role perception explain unique variance in either helping or taking charge, and that role breadth moderates the relationships between procedural justice and both helping and taking charge. The authors discuss implications of these findings for OCB theory and research, as well as for managerial practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the Scheduling of Systems of UAVs and Fuel Service Stations for Long-Term Mission Fulfillment

The duration of missions that can be accomplished by a system of unmanned aerial vehicles (UAVs) is limited by the battery or fuel capacity of its constituent UAVs. However, a system of UAVs that is supported by automated refueling stations may support long term or even indefinite duration missions. We develop a mixed integer linear program (MILP) model to formalize the problem of scheduling a system of UAVs and multiple shared bases in disparate geographic locations. There are mission trajectories that must be followed by at least one UAV. A UAV may hand off the mission to another in order to return to base for fuel. To address the computational complexity of the MILP formulation, we develop a genetic algorithm to find feasible solutions when a state-of-the-art solver such as CPLEX cannot. In practice, the approach allows for a long-term mission to receive uninterrupted UAV service by successively handing off the task to replacement UAVs served by geographically distributed shared bases.     

Detection of sub-tidal mussel beds on rocky reefs using acoustics

The collection of recently settled wild mussels from beach-cast seaweed provides the seed for a large and rapidly expanding mussel aquaculture industry in New Zealand, but the locations of adult populations producing this seed are unknown. Traditional methods of assessing sub-tidal habitats of rocky reefs (diver census, video camera drops) are neither cost-effective nor practical for the relatively large spatial scales involved. Remote sensing tools offer solutions to this problem. We tested the ability of the acoustic seafloor classification system, Quester Tangent Corporation (QTC) Impact, to detect the presence of green-lipped mussel (Perna canaliculus) populations on sub-tidal rocky reefs. Acoustic data were collected from a range of visual subtidal habitats, combined, and analysed using QTC Impact's principal component analysis and clustering software. Discriminant function analysis assessed whether visually distinctive habitats could be correctly classified using this acoustic data only. Consistent and reliable classifications were found for continuous mussel beds (100% correct, 0% misclassification from other habitat types), and sand, while the other various classes of rocky reef habitats (i.e. reef with varying levels of biological cover of kelps and encrusting invertebrates, including occasional mussel patches at one site) were identifiable to a general class of rocky reef, without significant mussel cover. These results demonstrate that QTC Impact can reliably discriminate subtidal mussel beds on rocky reefs from other habitats, making it feasible to proceed with large-scale mapping.     

Characterization of IS1547, a new member of the IS900 family in the Mycobacterium tuberculosis complex, and its association with IS6110

Unlike classically defined insertion sequence (IS) elements, which are delimited by their inverted terminal repeats, some IS elements do not have inverted terminal repeats. Among this group of atypical IS elements, IS116, IS900, IS901, and IS1110 have been proposed as members of the IS900 family of elements, not only because they do not have inverted terminal repeats but also because they share other features such as homologous transposases and particular insertion sites. In this study, we report a newly identified IS sequence, IS1547, which was first identified in a clinical isolate of Mycobacterium tuberculosis. Its structure, insertion site, and putative transposase all conform with the conventions of the IS900 family, suggesting that it is a new member of this family. IS1547 was detected only in isolates of the M. tuberculosis complex, where it had highly polymorphic restriction fragment length polymorphism patterns, suggesting that it may be a useful genetic marker for identifying isolates of the M. tuberculosis complex and for distinguishing different strains of M. tuberculosis. ipl is a preferential locus for IS6110 insertion where there are eight known different insertion sites for IS6110. Surprisingly, the DNA sequence of ipl is now known to be a part of IS1547, meaning that IS1547 is a preferential site for IS6110 insertion.     

Therapist experience and the stresses of psychotherapeutic work.

A questionnaire survey of 227 licensed psychologists (aged 27–76 yrs) identified 5 stress factors associated with the nature of psychotherapeutic work (maintaining the therapeutic relationship, scheduling, professional doubt, overinvolvement, and personal depletion) and 5 associated with patient behaviors (negative affect, resistance, psychopathological symptoms, suicidal threats, and passive-aggressive behaviors). Less stress was reported by older Ss and those with moderate caseloads. (PsycINFO Database Record (c) 2010 APA, all rights reserved)