Iterative design for active control of fluid flow

This paper considers iterative controller design for planar Poiseuille flow by model unfalsification and controller redesign. The main contribution is to show that model-unfalsification-based iterative design can be useful in flow control problems. The a priori knowledge of the dynamics of the sampled system is obtained from the analytic approximation of the Navier-Stokes equations by a Galerkin method. Pole-positions, expected model orders and feasible dynamic variations are valuable prior knowledge which can be taken into account in the uncertainty-model unfalsification-based iterative design scheme developed

The Effect of a Type I Photoinitiator on Cure Kinetics and Cell Toxicity in Projection-Microstereolithography

AbstractProjection-microstereolithography is an additive manufacturing technique based on the spatially controlled solidification of a liquid photopolymer on exposure to digitally manipulated light patterns. This study presents a methodology to evaluate the effect of a type-I photoinitiator on the reaction kinetics in the process and the cytocompatibility of the produced components. While the reaction speed and degree of conversion were heavily dependent on the applied amount of the initiator, a clear toxic effect was observed with all tested concentrations, and a post-processing step of 7 days was required to leach out the initiator residues

Interpersonal interactions for haptic guidance during maximum forward reaching

Caregiver-patient interactions rely on interpersonal coordination (IPC) involving the haptic and visual modalities. We investigated in healthy individuals spontaneous IPC during joint maximum forward reaching. A 'contact-provider' (CP; n=2) kept light interpersonal touch (IPT) laterally with the wrist of the extended arm of a forward reaching, blind-folded 'contact-receiver' (CR; n=22). Due to the stance configuration, CP was intrinsically more stable. CR received haptic feedback during forward reaching in two ways: (1) presence of a light object (OBT) at the fingertips, (2) provision of IPT. CP delivered IPT with or without vision or tracked manually with vision but without IPT. CR's variabilities of Centre-of-Pressure velocity (CoP) and wrist velocity, interpersonal cross-correlations and time lags served as outcome variables. OBT presence increased CR's reaching amplitude and reduced postural variability in the reach end-state. CR's variability was lowest when CP applied IPT without vision. OBT decreased the strength of IPC. Correlation time lags indicated that CP retained a predominantly reactive mode with CR taking the lead. When CP had no vision, presumably preventing an effect of visual dominance, OBT presence made a qualitative difference: with OBT absent, CP was leading CR. This observation might indicate a switch in CR's coordinative strategy by attending mainly to CP's haptic 'anchor'. Our paradigm implies that in clinical settings the sensorimotor states of both interacting partners need to be considered. We speculate that haptic guidance by a caregiver is more effective when IPT resembles the only link between both partners

Wilson Lines off the Light-cone in TMD PDFs

Transverse Momentum Dependent (TMD) parton distribution functions (PDFs) also take into account the transverse momentum ($p_T$) of the partons. The $p_T$-integrated analogues can be linked directly to quark and gluon matrix elements using the operator product expansion in QCD, involving operators of definite twist. TMDs also involve operators of higher twist, which are not suppressed by powers of the hard scale, however. Taking into account gauge links that no longer are along the light-cone, one finds that new distribution functions arise. They appear at leading order in the description of azimuthal asymmetries in high-energy scattering processes. In analogy to the collinear operator expansion, we define a universal set of TMDs of definite rank and point out the importance for phenomenology.Comment: 12 pages, presented by the first author at the Light-Cone Conference 2013, May 20-24, 2013, Skiathos, Greece. To be published in Few Body System

The effect of dietary supplementation with n-3 polyunsaturated fatty acids on the synthesis of interleukin-1 and tumor necrosis factor by mononuclear cells

Contains fulltext : 4487.pdf (publisher's version ) (Open Access

3-Substituted biquinolinium inhibitors of AraC family transcriptional activator VirF from S. flexneri obtained through in situ chemical ionization of 3,4-disubstituted dihydroquinolines

During a structure-activity relationship optimization campaign to develop an inhibitor of AraC family transcriptional activators, we discovered an unexpected transformation of a previously reported inhibitor that occurs under the assay conditions. Once placed in the assay media, the 3,4-disubstituted dihydroquinoline core of the active analogue rapidly undergoes a decomposition reaction to a quaternary 3-substituted biquinolinium. Further examination established an SAR for this chemotype while also demonstrating its resilience to irreversible binding of biologically relevant nucleophiles

Towards a new philosophy of engineering: structuring the complex problems from the sustainability discourse

This dissertation considers three broad issues which emerge from the sustainability discourse. First is the nature of the discourse itself, particularly the underlying philosophical positions which are represented. Second, is the nature of the highly complex types of problem which the discourse exposes. And third is whether the engineering profession, as it is practised currently, is adequate to deal with such problems. The sustainability discourse exposes two distinct, fundamentally irreconcilable philosophical positions. The first, “sustainable development”, considers humanity to be privileged in relation to all other species and ecosystems. It is only incumbent upon us to look after the environment to the extent to which it is in our interests to do so. The second, “sustainability”, sees humanity as having no special moral privilege and recognises the moral status of other species, ecosystems, and even wilderness areas. Thus, sustainability imposes upon us a moral obligation to take their status into account and not to degrade or to destroy them. These two conflicting positions give rise to extremely complex problems. An innovative taxonomy of problem complexity has been developed which identifies three broad categories of problem. Of particular interest in this dissertation is the most complex of these, referred to here as the Type 3 problem. The Type 3 problem recognises the systemic complexity of the problem situation but also includes differences of the domain of interests as a fundamental, constituent part of the problem itself. Hence, established systems analysis techniques and reductionist approaches do not work. The domain of interests will typically have disparate ideas and positions, which may be entirely irreconcilable. The dissertation explores the development of philosophy of science, particularly in the last 70 years. It is noted that, unlike the philosophy of science, the philosophy of engineering has not been influenced by developments of critical theory, cultural theory, and postmodernism, which have had significant impact in late 20th-century Western society. This is seen as a constraint on the practice of engineering. Thus, a set of philosophical principles for sustainable engineering practice is developed. Such a change in the philosophy underlying the practice of engineering is seen as necessary if engineers are to engage with and contribute to the resolution of Type 3 problems. Two particular challenges must be overcome, if Type 3 problems are to be satisfactorily resolved. First, issues of belief, values, and morals are central to this problem type and must be included in problem consideration. And second, the problem situation is usually so complex that it challenges the capacity of human cognition to deal with it. Consequently, extensive consideration is given to cognitive and behavioural psychology, in particular to choice, judgement and decision-making in uncertainty. A novel problem-structuring approach is developed on three levels. A set philosophical foundation is established; a theoretical framework, based on general systems theory and established behavioural and cognitive psychological theory, is devised; and a set of tools is proposed to model Type 3 complex problems as a dynamic systems. The approach is different to other systems approaches, in that it enables qualitative exploration of the system to plausible, hypothetical disturbances. The problem-structuring approach is applied in a case study, which relates to the development of a water subsystem for a major metropolis (Sydney, Australia). The technique is also used to critique existing infrastructure planning processes and to propose an alternative approach

Ku70 Serine 155 mediates Aurora B inhibition and activation of the DNA damage response

The Ku heterodimer (Ku70/Ku80) is the central DNA binding component of the classical non-homologous end joining (NHEJ) pathway that repairs DNA double-stranded breaks (DSBs), serving as the scaffold for the formation of the NHEJ complex. Here we show that Ku70 is phosphorylated on Serine 155 in response to DNA damage. Expression of Ku70 bearing a S155 phosphomimetic substitution (Ku70 S155D) in Ku70-deficient mouse embryonic fibroblasts (MEFs) triggered cell cycle arrest at multiple checkpoints and altered expression of several cell cycle regulators in absence of DNA damage. Cells expressing Ku70 S155D exhibited a constitutive DNA damage response, including ATM activation, H2AX phosphorylation and 53BP1 foci formation. Ku70 S155D was found to interact with Aurora B and to have an inhibitory effect on Aurora B kinase activity. Lastly, we demonstrate that Ku and Aurora B interact following ionizing radiation treatment and that Aurora B inhibition in response to DNA damage is dependent upon Ku70 S155 phosphorylation. This uncovers a new pathway where Ku may relay signaling to Aurora B to enforce cell cycle arrest in response to DNA damage

1/f Noise in Electron Glasses

We show that 1/f noise is produced in a 3D electron glass by charge fluctuations due to electrons hopping between isolated sites and a percolating network at low temperatures. The low frequency noise spectrum goes as \omega^{-\alpha} with \alpha slightly larger than 1. This result together with the temperature dependence of \alpha and the noise amplitude are in good agreement with the recent experiments. These results hold true both with a flat, noninteracting density of states and with a density of states that includes Coulomb interactions. In the latter case, the density of states has a Coulomb gap that fills in with increasing temperature. For a large Coulomb gap width, this density of states gives a dc conductivity with a hopping exponent of approximately 0.75 which has been observed in recent experiments. For a small Coulomb gap width, the hopping exponent approximately 0.5.Comment: 8 pages, Latex, 6 encapsulated postscript figures, to be published in Phys. Rev.

Phase separation in star polymer-colloid mixtures

We examine the demixing transition in star polymer-colloid mixtures for star arm numbers f=2,6,16,32 and different star-colloid size ratios. Theoretically, we solve the thermodynamically self-consistent Rogers-Young integral equations for binary mixtures using three effective pair potentials obtained from direct molecular computer simulations. The numerical results show a spinodal instability. The demixing binodals are approximately calculated, and found to be consistent with experimental observations.Comment: 4 pages, 4 figures, submitted to PR