Breakdown Of The Laminar Flow Regime In Permeable-walled Ducts

The stability of laminar flow in a parallel-plate channel having one permeable bounding wall is investigated by means of linear theory. The analysis lakes account of the coupling of the disturbance, fields in the channel and in the permeable material and of velocity slip at the surface of the permeable wall. Complementary experiments are performed in which the breakdown of the laminar regime in flat rectangular ducts is identified from pressure-drop measurements and from flow visualization studies. The experiments cover the range of slip velocities from 15-30 percent of the mean velocity and, in addition, the case of zero slip (impermeable walls). In the slip range of the experiments, the instability Reynolds number results of both analysis and experiment lie below the corresponding values for the case of the impermeable-walled duct. Furthermore, in this range, the instability Reynolds numbers are rather insensitive to variations in the slip velocity. Quantitative agreement between analysis and experiment was found to be somewhat belter in the slip range than for the impermeable-walled duct. © 1973 by ASME

Direct transition to high-dimensional chaos through a global bifurcation

In the present work we report on a genuine route by which a high-dimensional (with d>4) chaotic attractor is created directly, i.e., without a low-dimensional chaotic attractor as an intermediate step. The high-dimensional chaotic set is created in a heteroclinic global bifurcation that yields an infinite number of unstable tori.The mechanism is illustrated using a system constructed by coupling three Lorenz oscillators. So, the route presented here can be considered a prototype for high-dimensional chaotic behavior just as the Lorenz model is for low-dimensional chaos.Comment: 7 page

The Ambivalence of Promising Technology

Issues of responsibility in the world of nanotechnology are becoming explicit with the emergence of a discourse on ‘responsible development’ of nanoscience and nanotechnologies. Much of this discourse centres on the ambivalences of nanotechnology and of promising technology in general. Actors must find means of dealing with these ambivalences. Actors’ actions and responses to ambivalence are shaped by their position and context, along with strategic games they are involved in, together with other actors. A number of interviews were conducted with industrial actors with the aim of uncovering their ethical stances towards responsible development of nanotechnology. The data shows that standard repertoires of justification of nanotechnological development were used. Thus, the industrial actors fell back on their position and associated responsibilities. Such responses reinforce a division of moral labour in which industrial actors and scientists can focus on the progress of science and technology, while other actors, such as NGOs, are expected to take care of broader considerations, such as ethical and social issues

Psi-series solutions of the cubic H\'{e}non-Heiles system and their convergence

The cubic H\'enon-Heiles system contains parameters, for most values of which, the system is not integrable. In such parameter regimes, the general solution is expressible in formal expansions about arbitrary movable branch points, the so-called psi-series expansions. In this paper, the convergence of known, as well as new, psi-series solutions on real time intervals is proved, thereby establishing that the formal solutions are actual solutions

Lorenz-like systems and classical dynamical equations with memory forcing: a new point of view for singling out the origin of chaos

A novel view for the emergence of chaos in Lorenz-like systems is presented. For such purpose, the Lorenz problem is reformulated in a classical mechanical form and it turns out to be equivalent to the problem of a damped and forced one dimensional motion of a particle in a two-well potential, with a forcing term depending on the ``memory'' of the particle past motion. The dynamics of the original Lorenz system in the new particle phase space can then be rewritten in terms of an one-dimensional first-exit-time problem. The emergence of chaos turns out to be due to the discontinuous solutions of the transcendental equation ruling the time for the particle to cross the intermediate potential wall. The whole problem is tackled analytically deriving a piecewise linearized Lorenz-like system which preserves all the essential properties of the original model.Comment: 48 pages, 25 figure

The Antimicrobial Peptide, Bactenecin 5, Supports Cell-Mediated but Not Humoral Immunity in the Context of a Mycobacterial Antigen Vaccine Model.

Bactenecin (Bac) 5 is a bovine antimicrobial peptide (AMP) capable of killing some species of bacteria through the inhibition of protein synthesis. Bac5 and other AMPs have also been shown to have chemotactic properties and can induce inflammatory cytokine expression by innate immune cells. Recently, AMPs have begun to be investigated for their potential use as novel vaccine adjuvants. In the current work, we characterise the functionality of Bac5 in vitro using murine macrophage-like cells, ex vivo using human tonsil tissue and in vivo using a murine model of vaccination. We report the effects of the peptide in isolation and in the context of co-presentation with mycobacterial antigen and whole, inert Bacillus subtilis spore antigens. We find that Bac5 can trigger the release of nitric oxide from murine macrophages and upregulate surface marker expression including CD86, MHC-I and MHC-II, in the absence of additional agonists. When coupled with mycobacterial Ag85 and B. subtilis spores, Bac5 also enhanced IFNγ secretion. We provide evidence that B. subtilis spores, but not the Bac5 peptide, act as strong adjuvants in promoting antigen-specific immunoglobulin production in Ag85B-vaccinated mice. Our findings suggest that Bac5 is an important regulator of the early cell-mediated host immune response

The Incredible Years Autism Spectrum and Language Delays Parent program: A pragmatic, feasibility randomized controlled trial

Behavior problems in children with autism spectrum disorders (ASD) are common and particularly stressful for parents. This study aimed to examine the feasibility of delivering a parenting program in existing services, and the feasibility of conducting a future large‐scale Randomized Controlled Trial evaluation of the effectiveness of the intervention. Parents of children aged 3–8 years with a diagnosis of ASD, or strongly suspected ASD were eligible to participate. A multicenter, pragmatic, feasibility randomized controlled trial was conducted in four specialist children's services in Wales. Families were randomly assigned to receive the Incredible Years® Autism Spectrum and Language Delays (IY‐ASLD) parent program immediately or to a wait‐list, treatment as usual control condition. IY‐ASLD sessions were delivered once a week for 12 weeks. The primary outcomes related to feasibility (recruitment, retention, fidelity, and acceptability). Preliminary outcome analyses were conducted using covariance models controlling for study site and baseline scores. From October 5 to December 19, 2016, 58 families were randomized, 29 to IY‐ASLD and 29 to control. Three parents did not attend any sessions while 19 (73%) completed the program. Fidelity of delivery was high (88%), as was satisfaction with the program. Fifty‐three (91%) completed the follow‐up measures. All 95% CIs for effect sizes included zero in exploratory outcome analyses. This study supports the feasibility of delivering the IY‐ASLD in existing services with good levels of acceptability and fidelity evident. A larger randomized controlled trial is required to examine the effectiveness of the program. Autism Res 2019. © 2019 International Society for Autism Research, Wiley Periodicals, Inc

Effect of thermomechanical processing defects on fatigue and fracture behaviour of forged magnesium

The microstructural origins of premature fatigue failures were investigated on a variety of forged components manufactured from AZ80 and ZK60 magnesium, both at the test specimen level and the full-scale component level. Both stress and strain-controlled approaches were used to characterize the macroscopically defect-free forged material behaviour as well as with varying levels of defect intensities. The effect of thermomechanical processing defects due to forging of a industrially relevant full-scale component were characterized and quantified using a variety of techniques. The fracture initiation and early crack growth behaviour was deterministically traced back to a combination of various effects having both geometric and microstructural origins, including poor fusion during forging, entrainment of contaminants sub-surface, as well as other inhomogeneities in the thermomechanical processing history.             At the test specimen level, the fracture behaviour under both stress and strain controlled uniaxial loading was characterized for forged AZ80 Mg and a structure-property relationship was developed. The fracture surface morphology was quantitatively assessed revealing key features which characterize the presence and severity of intrinsic forging defects.  A significant degradation in fatigue performance was observed as a result of forging defects accelerating fracture initiation and early crack growth, up to 6 times reduction in life (relative to the defect free material) under constant amplitude fully reversed fatigue loading.             At the full-scale component level, the fatigue and fracture behaviour under combined structural loading was also characterized for a number of ZK60 forged components with varying levels of intrinsic thermomechanical processing defects. A novel in-situ non-contact approach (utilizing Digital-Image Correlation) was used as a screening test to establish the presence of these intrinsic defects and reliably predict their effect on the final fracture behaviour in an accelerated manner compared to conventional methods