Berry phase in open quantum systems: a quantum Langevin equation approach

The evolution of a two level system with a slowly varying Hamiltonian, modeled as a spin 1/2 in a slowly varying magnetic field, and interacting with a quantum environment, modeled as a bath of harmonic oscillators is analyzed using a quantum Langevin approach. This allows to easily obtain the dissipation time and the correction to the Berry phase in the case of an adiabatic cyclic evolution.

Open Adoption: Adoptive Parents' Experiences of Birth Family Contact and Talking to Their Child about Adoption

The trend towards more open adoption presents adopters with unique parenting challenges associated with satisfying the child’s curiosity about their origins, and maintaining relationships with birth family through contact. This paper focuses on the experiences of 20 sets of adoptive parents who were interviewed as part of the Northern Ireland Care Pathways and Outcomes Study. Interviews were analysed following the principles of Interpretative Phenomenological Analysis (IPA). It explores adoptive parents’ experience of talking to their child about adoption, and of post-adoption contact with members of the birth family. Adopters discussed adoption sensitively with their child, but were concerned that difficult and complex family histories would present a risk to the child’s self-esteem and emotional well-being. All forms of contact proved emotionally and practically burdensome, however adopters were committed to making it work for the child’s benefit, and were open to increased contact should the child wish it in the future. There was little relationship with birth family outside of formal contact. The study reveals a need for a mechanism to facilitate communication with birth family if adopters are to be able to respond to the child’s changing need for contact and information.

Stochastic Sznajd Model in open community

We extend the Sznajd Model for opinion formation by introducing persuasion probabilities for opinions. Moreover, we couple the system to an environment which mimics the application of the opinion. This results in a feedback, representing single-state opinion transitions in opposite to the two-state opinion transitions for persuading other people. We call this model opinion formation in an open community (OFOC). It can be seen as "stochastic extension of the Sznajd model for an open community, because it allows for "special choice of parameters to recover the original Sznajd model. We demonstrate the effect of feedback in the OFOC model by applying it to a scenario in which, e.g., opinion B is worse then opinion A but easier explained to other people. Casually formulated we analyzed the question, how much better one has to be, in order to persuade other people, provided the opinion is worse. Our results reveal a linear relation between the transition probability for opinion B and the influence of the environment on B.

Effect of activated carbon xerogel pore size on the capacitance performance of ionic liquid electrolytes

The use of ionic liquid (IL) electrolytes promises to improve the energy density of electrochemical capacitors (ECs) by allowing for operation at higher voltages. Several studies have also shown that the pore size distribution of materials used to produce electrodes is an important factor in determining EC performance. In this research the capacitative, energy and power performance of ILs 1-ethyl-3- methylimidazolium tetrafluoroborate (EMImBF4), 1-ethyl-3-methylimidazolium dicyanamide (EMImN(CN)2), 1,2-dimethyl-3-propylimidazolium bis(trifluoromethylsulfonyl)imide (DMPImTFSI), and 1-butyl-3-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate (BMPyT(F5Et)PF3) were studied and compared with the commercially utilised organic electrolyte 1M tetraethylammonium tetrafluoroborate solution in anhydrous propylene carbonate (Et4NBF4–PC 1 M). To assess the effect of pore size on IL performance, controlled porosity carbons were produced from phenolic resins activated in CO2. The carbon samples were characterised by nitrogen adsorption– desorption at 77 K and the relevant electrochemical behaviour was characterised by cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy. The best capacitance performance was obtained for the activated carbon xerogel with average pore diameter 3.5 nm, whereas the optimum rate performance was obtained for the activated carbon xerogel with average pore diameter 6 nm. When combined in an EC with IL electrolyte EMImBF4 a specific capacitance of 210 F g1 was obtained for activated carbon sample with average pore diameter 3.5 nm at an operating voltage of 3 V. The activated carbon sample with average pore diameter 6 nm allowed for maximum capacitance retention of approximately 70% at 64 mA cm2.

Eyes open to stem cells: safety trial may pave the way for cell therapy to treat retinal disease in patients

A clinical trial using human embryonic stem cell (hESC) therapy for an inherited retinal degenerative disease is about to commence. The Advanced Cell Technology (ACT) trial will treat patients with Stargardt's macular dystrophy using transplanted retinal pigment epithelium derived from hESCs. Currently, no effective treatment is available for Stargardt's disease so a stem cell-based therapy that can slow progression of this blinding condition could represent a significant breakthrough. While there are some hurdles to clear, the ACT trial is a fine example of translational research that could eventually pave the way for a range of stem cell therapies for the retina and other tissues.

Comparative Characterisation of 3-D Hydroxyapatite Scaffolds Developed via Replication of Synthetic Polymer Foams and Natural Marine Sponges

The production of complex inorganic forms, based on naturally occurring scaffolds offers an exciting avenue for the construction of a new generation of ceramic-based bone substitute scaffolds. The following study reports an investigation into the architecture (porosity, pore size distribution, pore interconnectivity and permeability), mechanical properties and cytotoxic response of hydroxyapatite bone substitutes produced using synthetic polymer foam and natural marine sponge performs. Infiltration of polyurethane foam (60 pores/in2) using a high solid content (80wt %), low viscosity (0.126Pas) hydroxyapatite slurry yielded 84-91% porous replica scaffolds with pore sizes ranging from 50µm - 1000µm (average pore size 577µm), 99.99% pore interconnectivity and a permeability value of 46.4 x10-10m2. Infiltration of the natural marine sponge, Spongia agaricina, yielded scaffolds with 56- 61% porosity, with 40% of pores between 0-50µm, 60% of pores between 50-500µm (average pore size 349 µm), 99.9% pore interconnectivity and a permeability value of 16.8 x10-10m2. The average compressive strengths and compressive moduli of the natural polymer foam and marine sponge replicas were 2.46±1.43MPa/0.099±0.014GPa and 8.4±0.83MPa /0.16±0.016GPa respectively. Cytotoxic response proved encouraging for the HA Spongia agaricina scaffolds; after 7 days in culture medium the scaffolds exhibited endothelial cells (HUVEC and HDMEC) and osteoblast (MG63) attachment, proliferation on the scaffold surface and penetration into the pores. It is proposed that the use of Spongia agaricina as a precursor material allows for the reliable and repeatable production of ceramic-based 3-D tissue engineered scaffolds exhibiting the desired architectural and mechanical characteristics for use as a bone 3 scaffold material. Moreover, the Spongia agaricina scaffolds produced exhibit no adverse cytotoxic response.

Factors affecting in vitro adherence of ureteral stent biofilm isolates to polyurethane

Adherence of bacteria to biomaterials is the first stage in the development of a device-related infection. The adherence of bacterial cells to biomaterials may be influenced by surface characteristics of the cell, its growth conditions and the biomaterial surface chemistry. Following growth in human urine, the cell surface,hydrophobicity and zeta potential of two ureteral stent biofilm isolates, Enterococcus faecalis and Escherichia coli, were significantly altered. In addition, the adherence of human urine-grown Enterococcus faecalis and Escherichia coli to polyurethane was significantly increased by up to 52.1% and 58.6%, respectively. Treatment of the polyurethane with human urine rendered the polymer surface more hydrophilic (mean advancing water contact angle reduced from 97.59 degrees to 26.37 degrees). However, organisms grown in human urine showed less adherence (up to 90.4%) to the treated polymer than those grown in Mueller-Hinton broth. The results presented in this study indicate that in vivo conditions should be simulated as far as possible when carrying out in vitro bacterial adherence assays, especially if assessing novel methods for reduction of adherence. (C) 1997 Elsevier Science B.V.

Catalysing open innovation through publicly funded R&D: A Comparison of University and Company-based research centres

Public funding of university and company-based R&D centres of excellence is widespread both in core and more peripheral regions. What is less well-known is whether these R&D centres can catalyse multi-directional, multi-actor and iterative innovation. Based on data from a real-time monitoring study, this article explores the development of 18 R&D centres’ external connections. University-based R&D centres establish more new connections than company-based centres and are more likely to be interacting with small or micro-firms. However, there is a general bias towards links with larger firms; micro, small and medium-sized enterprises also are less likely to be involved in collaborative R&D with research centres than other types of relationships. The results suggest the potential for R&D centres to act as a catalyst for open innovation but emphasise the need to ensure that the focus of the R&D being conducted is relevant to the needs of smaller firms.

Biological efficacy of electroless-deposited silver on plasma activated polyurethane

Silver coating of catheters has been shown to have inhibitory effects on bacterial growth and adhesion to catheter surfaces. In this study, plasma-modification was used to enhance the adhesion of an electroless silver coating on polyurethane. Both the antibacterial and antiadhesive properties of these coatings were investigated. Bacterial growth was inhibited in cultures exposed to silver-treated polyurethane compared to unmodified polyurethane. Higher growth inhibition was observed for polyurethane surfaces with lower silver coverage. Bacterial adhesion was completely inhibited on all silver-coated surfaces.