Experiences of the use of riverine nutrient models in stakeholder dialogues

The potential of models to assist in stakeholder dialogues is assessed regarding options for the reduction of riverine nitrogen loads in a 357‐km² river basin in south central Sweden. Scenarios of remedies based on stakeholders' suggestions were used to stimulate discussions in a panel incorporating farmers, municipality staff, politicians and technical advisers. The farmers perceived the model‐derived discussion material as valuable, although only average conditions at a generic farm were simulated. The panellists demonstrated caution when using regionalized information, but did not request quantitative uncertainty estimates. There was a desire to have phosphorus included in the model‐derived discussion material and to include the impacts of other environmental goals than ‘no eutrophication’. The inclusion of different stakeholder groups in the panel sessions was acknowledged as a way to establish a shared perception of the existing environmental status of the basin and to define the pros and cons of various remedies. This was seen by the panellists as a way to facilitate local implementation of the Water Framework Directive (WFD). Use of model‐stimulated local stakeholder panels is also a way to ensure that involved stakeholders perceive local environmental goals as realistic and acceptable. However, to establish river‐basin stakeholder dialogues as part of the nation‐wide implementation of the WFD directive, it will be necessary to develop a model approach that can be used by local advisers. Perhaps the most critical factor is the moderators' ability to provide an atmosphere of mutual respect between all those involved in contrast to performing one‐way lectures to the participants.     

Glass transition temperature of glasses in the SiO2-Na2O-CaO-P2O5-Al2O3-B2O3 system

A total of 24 glasses in or near the bioactive region in the system SiO₂-Na₂O-CaO-P₂O₅-Al₂O₃-B₂O₃ were studied. By differential thermal analysis their glass transition temperatures,T _g, were determined. On basis of an experimental plan for 16 glasses, two phenomenological equations describing the relationship betweenT _g and glass composition were developed. The equations describeT _g within the compositional ranges: SiO₂, 38.0–65.5 Na₂O, 15.0–30.0; CaO, 10.0–25.0; P₂O₅, 0–8.0; B₂O₃, 0–3.0; Al₂O₃, 0–3.0 wt%. The glass transition temperature shows a linear dependence of the Na₂O content. The higher the Na₂O content, the lower theT _g. Compositional alterations not including Na₂O influencesT _g little in comparison with changes in the Na₂O content.     

Routine FE determination of stress intensity factors at curved crack fronts using an influence function technique

A remarkably simple and accurate one-step application of the finite element (FE) method is suggested as a means for the engineer's routine determination of stress intensity factors in linear fracture mechanics for complicated non-symmetric geometries with three-dimensional states of stress and curved crack fronts. The vector-valued influence functions (Green functions) used here are a special kind of weight functions. Mode separation is inherent to the present procedure. Numerical examples demonstrate the versatility of the method. Accuracies within 1% are easily achieved. Detailed guidance to the design of the FE mesh at the crack front is given. Any standard FE code can be used, without requirements for special finite or boundary elements. In retrospect, the present method can be seen as a rather trivial calculation technique which has been made feasible and attractive by the capabilities of today's computers and softwares.     

A graphical characterization of lattice conditional independence models

Lattice conditional independence (LCI) models for multivariate normal data recently have been introduced for the analysis of non-monotone missing data patterns and of nonnested dependent linear regression models (≡ seemingly unrelated regressions). It is shown here that the class of LCI models coincides with a subclass of the class of graphical Markov models determined by acyclic digraphs (ADGs), namely, the subclass of transitive ADG models. An explicit graph-theoretic characterization of those ADGs that are Markov equivalent to some transitive ADG is obtained. This characterization allows one to determine whether a specific ADG D is Markov equivalent to some transitive ADG, hence to some LCI model, in polynomial time, without an exhaustive search of the (possibly superexponentially large) equivalence class [D]. These results do not require the existence or positivity of joint densities. This revised version was published online in June 2006 with corrections to the Cover Date.     

WROUGHT TiAl ALLOY DESIGN

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Postoperative lens position preoperatively determined by Scheimpflug photography

The position of the artificial lens has an important influence on refractive power calculation. We compared the position of the crystalline lens with that of the artificial lens after cataract surgery by means of Scheimpflug photography. A difference in position of approximately 0.8 mm in the anterior direction could be determined.     

A non-nitrergic smooth muscle relaxant factor released from rat urinary bladder by muscarinic receptor stimulation

PURPOSE: To study the possible release of a relaxant factor from isolated rat bladder tissue. MATERIALS AND METHODS: Thoracic aortae and urinary bladders were obtained from 55 female Sprague-Dawley rats. The bladder body was used in its original tubular shape as the donor tissue in a co-axial bioassay system, and the aorta served as acceptor tissue. RESULTS: In a co-axial bioassay system with endothelium-free, norepinephrine-contracted, rat aortic preparations mounted within urothelium-intact urinary bladder, carbachol caused a concentration-dependent relaxation, amounting to 64+/-7% (n = 10) of the induced contraction, suggesting release of a relaxing factor. The relaxant effect of carbachol was lost if the urinary bladder segment was removed. However, the relaxation was affected neither by removal of the urothelium, nor by bladder segment inversion. It was resistant to inhibition of the L-arginine/nitric oxide and cyclo-oxygenase pathways, and unaffected by beta-adrenoceptor blockade and K+ channel inhibition. The relaxation was not associated with any significant changes in the intracellular levels of cGMP or cAMP. CONCLUSION: A previously unrecognized non-adrenergic, non-nitrergic, non-prostanoid inhibitory mediator is released from the rat urinary bladder by muscarinic receptor stimulation. The physiological importance of such a factor remains to be established.