A simplex-like search method for bi-objective optimization

We describe a new algorithm for bi-objective optimization, similar to the Nelder Mead simplex algorithm, widely used for single objective optimization. For diferentiable bi-objective functions on a continuous search space, internal Pareto optima occur where the two gradient vectors point in opposite directions. So such optima may be located by minimizing the cosine of the angle between these vectors. This requires a complex rather than a simplex, so we term the technique the \cosine seeking complex". An extra beneft of this approach is that a successful search identifes the direction of the effcient curve of Pareto points, expediting further searches. Results are presented for some standard test functions. The method presented is quite complicated and space considerations here preclude complete details. We hope to publish a fuller description in another place

Stratabound arsenic and vein antimony mineralisation in Silurian greywackes at Glendinning, south Scotland

Stratiform and disseminated pyrite-arsenopyrite concentrations are overprinted by fracturecontrolled polymetallic mineralisation including stibnite through at least tens of metres of Silurian sediments at Glendinning, near Langholm. Three shallow boreholes were drilled on an anomaly defined by VLF-EM and II? surveys and by antimony values X0 ppm in thin B-C horizon soils. A parallel conductive zone with an accompanying soil anomaly but lacking an IP response was investigated by a fourth hole. The stratabound sulphides form disseminations and bands parallel to the bedding and are particularly concentrated in intraformational breccia units regarded as debris flows, which, together with the presence of smaIl scale slump folds in the greywackes, testify to the existence of an unstable slope during sedimentation. The thickest such unit has a true thickness of 4 m and together with 8 m of adjoining greywackes grades 0.7% As. Phases of fracture-controlled Fe-As-Sb-Pb- Zn-Cu-(?)Hg mineralisation associated with widespread dolomite and quartz veinlets and narrow breccia veins are superimposed on the stratabound mineralisation. Their spatial association with the stratabound mineralisation, the presence of up to 0.33% Sb in the stratiform arsenopyrite and as much as 5% As in the stratiform pyrite, favour a common source for the arsenic and antimony. This source was probably a synsedimentary metal accumulation in a mid or lower fan environment where euxinic conditions periodically developed

Multi-objective engineering shape optimization using differential evolution interfaced to the Nimrod/O tool

This paper presents an enhancement of the Nimrod/O optimization tool by interfacing DEMO, an external multiobjective optimization algorithm. DEMO is a variant of differential evolution – an algorithm that has attained much popularity in the research community, and this work represents the first time that true multiobjective optimizations have been performed with Nimrod/O. A modification to the DEMO code enables multiple objectives to be evaluated concurrently. With Nimrod/O’s support for parallelism, this can reduce the wall-clock time significantly for compute intensive objective function evaluations. We describe the usage and implementation of the interface and present two optimizations. The first is a two objective mathematical function in which the Pareto front is successfully found after only 30 generations. The second test case is the three-objective shape optimization of a rib-reinforced wall bracket using the Finite Element software, Code_Aster. The interfacing of the already successful packages of Nimrod/O and DEMO yields a solution that we believe can benefit a wide community, both industrial and academic

Retinoid isomerase inhibitors impair but do not block mammalian cone photoreceptor function

Visual function in vertebrates critically depends on the continuous regeneration of visual pigments in rod and cone photoreceptors. RPE65 is a well-established retinoid isomerase in the pigment epithelium that regenerates rhodopsin during the rod visual cycle; however, its contribution to the regeneration of cone pigments remains obscure. In this study, we use potent and selective RPE65 inhibitors in rod- and cone-dominant animal models to discern the role of this enzyme in cone-mediated vision. We confirm that retinylamine and emixustat-family compounds selectively inhibit RPE65 over DES1, the putative retinoid isomerase of the intraretinal visual cycle. In vivo and ex vivo electroretinography experiments in Gnat1-/- mice demonstrate that acute administration of RPE65 inhibitors after a bleach suppresses the late, slow phase of cone dark adaptation without affecting the initial rapid portion, which reflects intraretinal visual cycle function. Acute administration of these compounds does not affect the light sensitivity of cone photoreceptors in mice during extended exposure to background light, but does slow all phases of subsequent dark recovery. We also show that cone function is only partially suppressed in cone-dominant ground squirrels and wild-type mice by multiday administration of an RPE65 inhibitor despite profound blockade of RPE65 activity. Complementary experiments in these animal models using the DES1 inhibitor fenretinide show more modest effects on cone recovery. Collectively, these studies demonstrate a role for continuous RPE65 activity in mammalian cone pigment regeneration and provide further evidence for RPE65-independent regeneration mechanisms

The Impact of a Sport-Based Service Learning Course on Participants’ Attitudes, Intentions and Actions Toward Social Change

Framed in the context of a sport-based service learning program that engages in interdepartmental university partnerships (including athletics), the current study focused on addressing the need to analyze the long-term impacts of service learning on students’ intentions and actions toward social change. Service learning courses have been shown to facilitate positive outcomes such as increased cultural competency and future intentions toward civic engagement (Bruening et al., 2010, 2014). Building on this knowledge, the current study used in-depth interviews to investigate the social justice-related attitudes, intentions, and behaviors of alumni of a college service learning through sport course. Individual interviews (n = 22) with participants who had completed at least one semester in the course indicated that the course was influential in developing their ability to recognize social inequities. Furthermore, participants indicated future intentions and current involvement in initiatives that address social inequities in their given areas of life. Theoretical and managerial implications for effective academic and intercollegiate athletic partnerships, helping to increase impactful civic engagement and learning opportunities for student-athletes and non-student-athletes, are provided

Neuronal pentraxins mediate synaptic refinement in the developing visual system

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